Unbalanced three-phase power supply device and power supply for evaluation

Abstract

To easily construct an environment of a test using unbalanced three-phase voltage including a zero-phase component.SOLUTION: An unbalanced three-phase power supply device 100 includes: a control circuit 1A including a voltage command generation part 3 and a pulse modulation signal generation circuit 4; and a main circuit 2A including a DC power supply DC, a three-phase inverter device INV and a three-phase transformation device T. External zero-phase-containing unbalanced three-phase voltage Vubo including external U-phase voltage Vou, external V-phase voltage Vov and external W-phase voltage Vow, which have phases, frequencies and amplitudes corresponding to phase command values Cphu, Cphv and Cphw and amplitude command values Camu, Camv and Camw of the U-phase, V-phase and W-phase of a predetermined zero-phase-containing unbalanced three-phase voltage of unbalanced three-phase voltage information IFubv received by the voltage command generation part 3 is output from the three-phase transformation device T by the control circuit 1A and the main circuit 2A. The DC power supply DC, the three-inverter device INV and the three-phase transformation device T have respective configurations which can output zero-phase components and mutual connection relation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an unbalanced three-phase power supply device and an evaluation power supply. [Background technology]

[0002] In distributed power systems such as photovoltaic power generation systems, a power conditioner (PCS), which is a power conversion device, is installed between a power generation device such as a photovoltaic power generation panel and a power grid. The power conditioner is equipped with an inverter that converts the generated power into AC power that matches the grid frequency, and a control device for the inverter. In addition to power conversion operations, such power conditioners are required to have an islanding prevention function that disconnects each distributed power generation system from the grid in the event of a power outage or the like in the grid, and a low voltage ride-through (LVRT) function that prevents unnecessary disconnection during a momentary voltage drop (momentary voltage drop) due to the aforementioned function (see paragraph 1 of Patent Document 1).

[0003] reference). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-063576 Summary of the Invention [Problem to be solved by the invention]

[0004] Regarding the distributed power system, a test for evaluating its ability to continue operation during a momentary sag has been specified. To perform such a test, it is necessary to supply a voltage or current generated during a short circuit or ground fault in the grid to the power conditioner under test. Conventionally, unbalanced three-phase voltage or current containing such zero-phase components has been supplied by, for example, artificially short-circuiting or grounding a distribution line. However, using such a method, it is difficult to establish a test environment for creating the desired short-circuit or ground fault condition.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a power supply device that can easily create a test environment using an unbalanced three-phase voltage or an unbalanced three-phase current that includes a zero-phase component. [Means for solving the problem]

[0006] In order to achieve the above object, an unbalanced three-phase power supply device according to an aspect of the present disclosure includes a voltage command generation unit that receives unbalanced three-phase voltage information including phase command values and amplitude command values for the U phase, V phase, and W phase of a zero-phase-containing unbalanced three-phase voltage that is an unbalanced three-phase voltage that includes a predetermined zero-phase component, and generates, based on the unbalanced three-phase voltage information, a U-phase voltage command, a V-phase voltage command, and a W-phase voltage command having phases, frequencies, and amplitudes that respectively correspond to the phase command values and amplitude command values for the U phase, V phase, and W phase of the predetermined zero-phase-containing unbalanced three-phase voltage. a control circuit including a pulse modulation signal generation circuit that outputs a U-phase pulse modulation signal, a V-phase pulse modulation signal, and a W-phase pulse modulation signal corresponding to the U-phase voltage command, the V-phase voltage command, and the W-phase voltage command generated by the voltage command generation circuit; a DC power supply that outputs a predetermined DC voltage; a U-phase inverter unit, a V-phase inverter unit, and a W-phase inverter unit, wherein the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit respectively generate the U-phase pulse modulation signal, the V-phase pulse modulation signal, and the W-phase pulse modulation signal from the pulse modulation signal generation circuit. a three-phase inverter device that generates, from the predetermined DC voltage from the DC power source, a U-phase voltage, a V-phase voltage, and a W-phase voltage having phases, frequencies, and amplitudes corresponding to phase command values and amplitude command values of the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase voltage, respectively, in accordance with the U-phase pulse modulation signal and the W-phase pulse modulation signal, thereby outputting an internal zero-phase-containing unbalanced three-phase voltage including the U-phase voltage, the V-phase voltage, and the W-phase voltage; a three-phase transformer in which the secondary winding of the V-phase winding section, the secondary winding of the W-phase winding section, and the secondary winding of the V-phase winding section are Y-connected, the neutral point of the secondary windings being the neutral point of the Y-connection, and the U-phase voltage, the V-phase voltage, and the W-phase voltage of the internal zero-phase-containing unbalanced three-phase voltage from the three-phase inverter device are input to the primary winding of the U-phase winding section, the primary winding of the V-phase winding section, and the primary winding of the W-phase winding section, respectively;The three-phase transformer device has various configurations and mutual connection relationships that enable it to output the zero-phase component of an external zero-phase-containing unbalanced three-phase voltage obtained by converting the internal zero-phase-containing unbalanced three-phase voltage in accordance with a turns ratio, and the external zero-phase-containing unbalanced three-phase voltage is output by the secondary winding of the U-phase winding unit, the secondary winding of the V-phase winding unit, the secondary winding of the W-phase winding unit, and the secondary winding neutral point, which are Y-connected in the three-phase transformer device.

[0007] Furthermore, an evaluation power supply according to another aspect of the present disclosure includes any of the unbalanced three-phase power supply devices described above, wherein the DC power supply is a converter that converts the three-phase voltage of the power grid into a DC voltage, and the secondary side of the three-phase transformer is an output terminal to which the device under evaluation is connected.

[0008] An unbalanced three-phase power supply device according to still another aspect of the present disclosure includes a current command generation unit that receives unbalanced three-phase current information including phase command values and amplitude command values for U-phase, V-phase, and W-phase of a zero-phase-containing unbalanced three-phase current that is an unbalanced three-phase current that includes a predetermined zero-phase component, and generates, based on the unbalanced three-phase current information, a U-phase current command, a V-phase current command, and a W-phase current command having phases, frequencies, and amplitudes of active components and reactive components that respectively correspond to the phase command values and amplitude command values for the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase current; a control circuit including a pulse modulation signal generation circuit that outputs a U-phase pulse modulation signal, a V-phase pulse modulation signal, and a W-phase pulse modulation signal corresponding to the U-phase current command, the V-phase current command, and the W-phase current command generated by the current command generation circuit; a DC power supply that outputs a predetermined DC voltage or DC current; a U-phase inverter unit, a V-phase inverter unit, and a W-phase inverter unit, wherein the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit respectively generate the U-phase pulse modulation signal, the V-phase pulse modulation signal, and the W-phase pulse modulation signal from the pulse modulation signal generation circuit. a three-phase inverter device that generates U-phase currents, V-phase currents, and W-phase currents having phases, frequencies, and amplitudes corresponding to U-phase, V-phase, and W-phase phase command values and active and reactive component amplitude command values of the predetermined zero-phase-containing unbalanced three-phase current, respectively, by using the predetermined DC voltage or DC current from the DC power source in accordance with the modulation signal and the W-phase pulse modulation signal, thereby outputting an internal zero-phase-containing unbalanced three-phase current including the U-phase current, the V-phase current, and the W-phase current; a three-phase transformer in which the secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, and the secondary winding of the W-phase winding section are Y-connected, the neutral point of the secondary windings is the neutral point of the Y-connection, and the U-phase current, the V-phase current, and the W-phase current of the internal zero-phase-containing unbalanced three-phase current from the three-phase inverter device are input to the primary winding of the U-phase winding section, the primary winding of the V-phase winding section, and the primary winding of the W-phase winding section, respectively; andThe three-phase transformer has various configurations and mutual connection relationships that enable it to output the zero-phase component of an external zero-phase-containing unbalanced three-phase current obtained by converting the internal zero-phase-containing unbalanced three-phase current in accordance with a turns ratio, and the external zero-phase-containing unbalanced three-phase current is output by the secondary winding of the U-phase winding unit, the secondary winding of the V-phase winding unit, the secondary winding of the W-phase winding unit, and the secondary winding neutral point, which are Y-connected in the three-phase transformer.

[0009] Furthermore, a power supply for evaluation according to another aspect of the present disclosure includes any of the unbalanced three-phase power supply devices described above, wherein the DC power supply is a converter that converts a three-phase voltage or three-phase current of a power grid into a DC voltage or DC current, and the secondary side of the three-phase transformer is an output terminal to which a device under evaluation is connected.

[0010] The present disclosure provides an effect of easily creating a test environment using an unbalanced three-phase voltage or an unbalanced three-phase current including a zero-sequence component. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a functional block diagram showing an example of the configuration of an unbalanced three-phase power supply device according to the first embodiment of the present disclosure. [Figure 2] FIG. 2 is a circuit diagram showing details of the main circuit of FIG. 1 including the first zero-phase output configuration. [Figure 3] FIG. 3 is a circuit diagram showing details of the main circuit of FIG. 1 including a second zero-phase output configuration. [Figure 4] FIG. 4 is a circuit diagram showing details of the main circuit of FIG. 1 including a third zero-phase output configuration. [Figure 5] FIG. 5 is a circuit diagram showing details of the main circuit of FIG. 1 including a fourth zero-phase output configuration. [Figure 6] FIG. 6 is a circuit diagram showing an example of the configuration of the control circuit of FIG. [Figure 7] FIG. 7 is an explanatory diagram for explaining an unbalanced three-phase electric quantity vector including a zero-sequence component. [Figure 8]FIG. 8 is a waveform diagram showing voltage waveforms at various parts of an unbalanced three-phase power supply device in a simulation of the unbalanced three-phase power supply device whose main circuit includes a first zero-phase output configuration. [Figure 9] FIG. 9 is a waveform diagram showing the waveform of the magnetic flux of the single-phase transformer of each phase of the three-phase transformer unit in a simulation of an unbalanced three-phase power supply device in which the main circuit includes a first zero-phase output configuration. [Figure 10] FIG. 10 is a waveform diagram showing the waveform of the magnetic flux in each leg of a three-phase five-legged core transformer in a simulation of an unbalanced three-phase power supply device whose main circuit includes a second zero-phase output configuration. [Figure 11] FIG. 11 is a waveform diagram showing voltage waveforms at various parts of an unbalanced three-phase power supply in a simulation of the unbalanced three-phase power supply whose main circuit includes a third zero-phase output configuration. [Figure 12] FIG. 12 is a functional block diagram showing an example of the configuration of a power supply for evaluation according to the second embodiment of the present disclosure. [Figure 13] FIG. 13 is a functional block diagram illustrating an example of the configuration of an unbalanced three-phase power supply device according to the third embodiment of the present disclosure. [Figure 14] FIG. 14 is a circuit diagram showing details of the main circuit of FIG. 13 including a fifth zero-phase output configuration. [Figure 15] FIG. 15 is a circuit diagram showing details of the main circuit of FIG. 13 including a sixth zero-phase output configuration. [Figure 16] FIG. 16 is a circuit diagram showing details of the main circuit of FIG. 13 including a seventh zero-phase output configuration. [Figure 17] FIG. 17 is a circuit diagram showing details of the main circuit of FIG. 13 including an eighth zero-phase output configuration. [Figure 18] FIG. 18 is a circuit diagram showing an example of the configuration of the control circuit of FIG. [Figure 19] FIG. 19 is a functional block diagram showing an example of the configuration of a power supply for evaluation according to the fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] An unbalanced three-phase power supply device according to an aspect of the present disclosure includes a voltage command generation unit that receives unbalanced three-phase voltage information including phase command values and amplitude command values for the U-phase, V-phase, and W-phase of a zero-phase-containing unbalanced three-phase voltage that is an unbalanced three-phase voltage including a predetermined zero-phase component, and generates a U-phase voltage command, a V-phase voltage command, and a W-phase voltage command having phases, frequencies, and amplitudes corresponding to the phase command values and amplitude command values for the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase voltage based on the unbalanced three-phase voltage information; a control circuit including a pulse modulation signal generation circuit that outputs a U-phase pulse modulation signal, a V-phase pulse modulation signal, and a W-phase pulse modulation signal corresponding to the W-phase voltage command, a DC power supply that outputs a predetermined DC voltage, and a U-phase inverter unit, a V-phase inverter unit, and a W-phase inverter unit, wherein the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit generate the predetermined DC voltage from the DC power supply in accordance with the U-phase pulse modulation signal, the V-phase pulse modulation signal, and the W-phase pulse modulation signal from the pulse modulation signal generation circuit, respectively. a three-phase inverter device that generates a U-phase voltage, a V-phase voltage, and a W-phase voltage having phases, frequencies, and amplitudes corresponding to phase command values and amplitude command values of the U-phase, V-phase, and W-phase of a zero-phase-containing unbalanced three-phase voltage, respectively, and thereby outputs an internal zero-phase-containing unbalanced three-phase voltage including the U-phase voltage, the V-phase voltage, and the W-phase voltage; a three-phase inverter device that includes a U-phase winding section, a V-phase winding section, a W-phase winding section, and a secondary winding neutral point, wherein the secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, and the secondary winding of the W-phase winding section are Y-connected, and the secondary winding neutral point is the neutral point of the Y-connection; and a three-phase transformer in which the U-phase voltage, the V-phase voltage, and the W-phase voltage of the internal zero-phase-containing unbalanced three-phase voltage from a three-phase inverter device are input to a primary winding of the U-phase winding section, a primary winding of the V-phase winding section, and a primary winding of the W-phase winding section, respectively, wherein the DC power supply, the three-phase inverter device, and the three-phase transformer device of the main circuit have respective configurations and mutual connection relationships that enable them to output the zero-phase component of an external zero-phase-containing unbalanced three-phase voltage obtained by converting the internal zero-phase-containing unbalanced three-phase voltage in the three-phase transformer device in accordance with a turns ratio,The external zero-phase-sequence-containing unbalanced three-phase voltage is output by the Y-connected secondary winding of the U-phase winding unit, the secondary winding of the V-phase winding unit, the secondary winding of the W-phase winding unit, and the secondary winding neutral point of the three-phase transformer. Here, the "turns ratio" refers to the ratio of the number of turns on the primary side to the number of turns on the secondary side in the three-phase transformer. The "pulse modulated signal" is a modulated signal modulated using a pulse, i.e., a rectangular wave, and includes at least a PWM signal (Pulse Width Modulation signal), a PAM signal (Pulse Amplitude Modulation signal), a PFM signal (Pulse Frequency Modulation signal), a PPM signal (Pulse Position Modulation signal), and a PDM signal (Pulse Density Modulation signal).

[0013] According to this configuration, the voltage command generating unit generates a U-phase voltage command, a V-phase voltage command, and a W-phase voltage command having phases, frequencies, and amplitudes corresponding to the phase command values and amplitude values of the U-phase, V-phase, and W-phase, respectively, of the received predetermined zero-phase-containing unbalanced three-phase voltage.

[0014] Then, the pulse modulation signal generation circuit outputs a U-phase pulse modulation signal, a V-phase pulse modulation signal, and a W-phase pulse modulation signal corresponding to the U-phase voltage command, the V-phase voltage command, and the W-phase voltage command generated by the voltage command generation unit.

[0015] Then, the U-phase inverter unit, V-phase inverter unit, and W-phase inverter unit of the three-phase inverter device generate, from a predetermined DC voltage from a DC power supply, a U-phase voltage, a V-phase voltage, and a W-phase voltage having phases, frequencies, and amplitudes corresponding to the phase command values and amplitude command values of the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase voltage, respectively, in accordance with the U-phase pulse modulation signal, V-phase pulse modulation signal, and W-phase pulse modulation signal from the pulse modulation signal generation circuit, thereby outputting an internal zero-phase-containing unbalanced three-phase voltage consisting of the U-phase voltage, V-phase voltage, and W-phase voltage.

[0016] In the three-phase transformer, the U-phase voltage, V-phase voltage, and W-phase voltage of the internal zero-phase-containing unbalanced three-phase voltage from the three-phase inverter device are input to the primary winding of the U-phase winding, the primary winding of the V-phase winding, and the primary winding of the W-phase winding, respectively. Here, the DC power supply of the main circuit, the three-phase inverter device, and the three-phase transformer have respective configurations and mutual connection relationships that enable them to output the zero-phase component of the external zero-phase-containing unbalanced three-phase voltage obtained by converting the internal zero-phase-containing unbalanced three-phase voltage in the three-phase transformer in accordance with the turns ratio, so that the external zero-phase-containing unbalanced three-phase voltage is output by the secondary winding of the U-phase winding, the secondary winding of the V-phase winding, the secondary winding of the W-phase winding, and the secondary winding neutral point, which are Y-connected in the three-phase transformer.

[0017] In other words, with the above configuration, the phase command values and amplitude command values for the U, V, and W phases of the received predetermined zero-phase-containing unbalanced three-phase voltage are processed independently for each of the U, V, and W phases in the unbalanced three-phase power supply, thereby enabling the generation of an external zero-phase-containing unbalanced three-phase voltage corresponding to the predetermined zero-phase-containing unbalanced three-phase voltage. Furthermore, the DC power supply, the three-phase inverter, and the three-phase transformer have respective configurations and mutual connections that enable them to output the zero-phase component of the generated external zero-phase-containing unbalanced three-phase voltage, enabling the output of the zero-phase component of the external zero-phase-containing unbalanced three-phase voltage. Therefore, an unbalanced three-phase power supply can be provided that can output an unbalanced three-phase voltage containing a desired zero-phase component by setting the desired zero-phase-containing three-phase unbalanced voltage to the predetermined zero-phase-containing unbalanced three-phase voltage. The unbalanced three-phase power supply generates an unbalanced three-phase voltage including a zero-phase component using a three-phase inverter device, and therefore, by using the unbalanced three-phase power supply, it is possible to easily create a test environment using an unbalanced three-phase voltage including a zero-phase component.

[0018] the main circuit includes a voltage sensor unit that detects voltages of U-phase, V-phase, and W-phase of the internal zero-phase-containing unbalanced three-phase voltage or the external zero-phase-containing unbalanced three-phase voltage, the control circuit further includes a voltage feedback control unit, and the voltage command generation unit includes a phase command value generation unit that adds phase command values of the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase voltage to the phases of the U-phase, V-phase, and W-phase of a reference internal three-phase sine wave, respectively, and outputs a U-phase phase command value, a V-phase phase command value, and a W-phase phase command value generated by the phase command value generation unit. a three-phase sine wave generator that compares the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value and their respective input timings with a sine table to generate U-phase sine waves, V-phase sine waves, and W-phase sine waves having phases, frequencies, and reference amplitudes corresponding to the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value, respectively; and a multiplier that multiplies the amplitude values of the U-phase sine waves, V-phase sine waves, and W-phase sine waves generated by the three-phase sine wave generator by amplitude command values of the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase voltage. and a voltage command amplitude determination unit that determines the amplitude of the U-phase sine wave, the amplitude of the V-phase sine wave, and the amplitude of the W-phase sine wave by calculating the amplitude of the U-phase voltage command, the V-phase voltage command, and the W-phase voltage command, thereby generating the U-phase voltage command, the V-phase voltage command, and the W-phase voltage command, and the voltage feedback control unit determines a U-phase voltage error, a V-phase voltage error, and a W-phase voltage command, which are errors of the U-phase, V-phase, and W-phase voltages of the internal zero-phase-containing unbalanced three-phase voltage or the external zero-phase-containing unbalanced three-phase voltage detected by the voltage sensor unit with respect to the U-phase voltage command, the V-phase voltage command, and the W-phase voltage command generated by the voltage command amplitude determination unit. and a voltage compensation unit that generates a U-phase voltage manipulated variable, a V-phase voltage manipulated variable, and a W-phase voltage manipulated variable by applying compensation to the U-phase voltage error, the V-phase voltage error, and the W-phase voltage error generated by the voltage error generation unit, respectively, wherein the pulse modulation signal generation circuit is a circuit that generates the U-phase pulse modulation signal, the V-phase pulse modulation signal, and the W-phase pulse modulation signal that correspond to the U-phase voltage manipulated variable, the V-phase voltage manipulated variable, and the W-phase voltage manipulated variable generated by the voltage compensation unit, respectively.

[0019] This configuration allows for a suitable configuration for generating voltage commands and pulse modulated signals. Furthermore, the U-, V-, and W-phase voltages of the internal zero-sequence-containing unbalanced three-phase voltage are feedback-controlled, thereby providing a suitable external zero-sequence-containing unbalanced three-phase voltage.

[0020] The DC power supply includes a U-phase DC power supply unit, a V-phase DC power supply unit, and a W-phase DC power supply unit, each outputting the predetermined DC voltage, and the three-phase inverter device includes a single-phase U-phase inverter that configures the U-phase inverter unit and generates an internal U-phase voltage having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of the U-phase of the predetermined zero-phase-containing unbalanced three-phase voltage from the U-phase DC power supply unit in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit; a single-phase V-phase inverter that generates, from the predetermined DC voltage from the V-phase DC power supply unit in accordance with a W-phase pulse modulation signal from the pulse modulation signal generation circuit, an internal V-phase voltage having a phase, frequency, and amplitude corresponding to a V-phase phase command value and an amplitude command value of the V-phase of the predetermined zero-phase-containing unbalanced three-phase voltage; and a single-phase W-phase inverter that generates, from the predetermined DC voltage from the W-phase DC power supply unit in accordance with the W-phase pulse modulation signal from the pulse modulation signal generation circuit, an internal W-phase voltage having a phase, frequency, and amplitude corresponding to a W-phase phase command value and an amplitude command value of the W-phase of the predetermined zero-phase-containing unbalanced three-phase voltage. a three-phase inverter unit including a U-phase inverter, a V-phase inverter, and a W-phase inverter, each outputting the internal zero-phase-sequence-containing unbalanced three-phase voltage including the internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage as the U-phase voltage, the V-phase voltage, and the W-phase voltage, respectively; the three-phase transformer device including a single-phase U-phase transformer constituting the U-phase winding section, a single-phase V-phase transformer constituting the V-phase winding section, and a single-phase W-phase transformer constituting the W-phase winding section; a three-phase transformer unit in which a secondary winding of a W-phase transformer is Y-connected and a neutral point of the Y-connection is the secondary winding neutral point, the internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage from the three-phase inverter unit are input to a primary winding of the U-phase transformer, a primary winding of the V-phase transformer, and a primary winding of the W-phase transformer, respectively, and the external zero-phase-sequence-containing unbalanced three-phase voltage obtained by converting the internal zero-phase-sequence-containing unbalanced three-phase voltage in accordance with a turns ratio is input to the Y-connected secondary winding of the U-phase transformer, the secondary winding of the V-phase transformer, andThe output may be a secondary winding of the W-phase transformer and a secondary winding neutral point of the secondary winding.

[0021] According to this configuration, an internal zero-phase-sequence-containing unbalanced three-phase voltage is generated in the main circuit, and the DC power supplies, three inverter units of the three-phase inverter device, and three winding units of the three-phase transformer device corresponding to the three phases are configured by three DC power supply units of the DC power supply, three single-phase inverters of the three-phase inverter unit, and three single-phase transformers of the three-phase transformer unit, which are independent of each other. Therefore, a current of the zero-phase component of the internal zero-phase-sequence-containing unbalanced three-phase voltage flows through the primary windings of the DC power supply units, single-phase inverters, and single-phase transformers corresponding to each phase in accordance with the phase voltages of the three mutually unbalanced phases. Furthermore, because the secondary windings of the single-phase transformers corresponding to the three phases are Y-connected, an external zero-phase-sequence-containing unbalanced three-phase voltage obtained by converting the internal zero-phase-sequence-containing unbalanced three-phase voltage in accordance with the turns ratio is output by the secondary windings and secondary winding neutral points of the single-phase transformers corresponding to the three Y-connected phases. As a result, it is possible to suitably construct a combination of a DC power supply, a three-phase inverter device, and a three-phase transformer device that can output the zero-phase component of an external zero-phase-containing unbalanced three-phase voltage.

[0022] The DC power supply includes a U-phase DC power supply unit, a V-phase DC power supply unit, and a W-phase DC power supply unit, each outputting the predetermined DC voltage, and the three-phase inverter device includes a single-phase U-phase inverter that configures the U-phase inverter unit and generates an internal U-phase voltage having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of the U-phase of the predetermined zero-phase-containing unbalanced three-phase voltage from the U-phase DC power supply unit in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit; a single-phase V-phase inverter configured to generate, from the predetermined DC voltage from the W-phase DC power supply unit, an internal V-phase voltage having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of the V-phase of the predetermined zero-phase-containing unbalanced three-phase voltage in accordance with a W-phase pulse modulation signal; and a single-phase W-phase inverter configured to generate, from the predetermined DC voltage from the W-phase DC power supply unit, an internal W-phase voltage having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of the W-phase of the predetermined zero-phase-containing unbalanced three-phase voltage in accordance with the W-phase pulse modulation signal from the pulse modulation signal generation circuit. a three-phase inverter unit including a U-phase inverter, a V-phase inverter, and a W-phase inverter, wherein the U-phase inverter, the V-phase inverter, and the W-phase inverter output the internal zero-phase-containing unbalanced three-phase voltage including the internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage as the U-phase voltage, the V-phase voltage, and the W-phase voltage, respectively; and the three-phase transformer device includes a three-phase five-legged core having a U-leg, a V-leg, a W-leg, and a pair of magnetic leakage legs, the U-phase winding portion provided on the U-phase leg, the V-phase winding portion provided on the V-phase leg, and the W-phase winding portion provided on the W-phase leg. a three-phase five-leg core transformer in which a secondary winding of the U-phase winding section, a secondary winding of the V-phase winding section, and a secondary winding of the W-phase winding section are Y-connected, and a neutral point of the Y-connection is the neutral point of the secondary winding; the internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage from the three-phase inverter unit are input to a primary winding of the U-phase winding section, a primary winding of the V-phase winding section, and a primary winding of the W-phase winding section of the three-phase five-leg core transformer, respectively; and an external zero-phase-sequence-containing unbalanced three-phase voltage obtained by converting the internal zero-phase-sequence-containing unbalanced three-phase voltage in accordance with a turns ratio isThe output may be from the secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, the secondary winding of the W-phase winding section, and the secondary winding neutral point of the secondary windings, which are all connected in the Y-connection of the three-phase five-legged core transformer.

[0023] According to this configuration, an internal zero-phase-sequence-containing unbalanced three-phase voltage is generated in the main circuit. The DC power supplies, inverter units, and winding units corresponding to the three phases are each configured by a mutually independent DC power supply unit, single-phase inverter, and phase winding unit of a three-phase five-leg core transformer. Therefore, a current of the zero-phase component of the internal zero-phase-sequence-containing unbalanced three-phase voltage flows through the primary windings of the DC power supply unit, single-phase inverter, and winding unit of the three-phase five-leg core transformer, respectively, in accordance with the mutually unbalanced phase voltages of the respective phases. Furthermore, a magnetic flux corresponding to the zero-phase component current flows through the magnetic leakage legs of the three-phase five-leg core. Furthermore, because the secondary windings of the three winding units of the three-phase five-leg core transformer are Y-connected, an external zero-phase-sequence-containing unbalanced three-phase voltage, which is converted in accordance with the turns ratio, is output from the secondary windings and secondary winding neutral points of the three Y-connected winding units of the three-phase five-leg core transformer. As a result, it is possible to suitably construct a combination of a DC power supply, a three-phase inverter device, and a three-phase transformer device that can output the zero-phase component of an external zero-phase-containing unbalanced three-phase voltage.

[0024] The DC power supply includes a positive DC power supply unit and a negative DC power supply unit which are connected in series with each other at a power supply neutral point and which respectively output the predetermined DC voltage, and the three-phase inverter device includes a U-phase inverter unit which generates an internal U-phase voltage having a phase, frequency and amplitude corresponding to a phase command value and an amplitude command value of the U-phase of the predetermined zero-phase-containing unbalanced three-phase voltage from the predetermined DC voltages from the positive DC power supply unit and the negative DC power supply unit in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit, and a V-phase inverter unit which generates an internal U-phase voltage having a phase, frequency and amplitude corresponding to a phase command value and an amplitude command value of the U-phase of the predetermined zero-phase-containing unbalanced three-phase voltage from the predetermined DC voltages from the positive DC power supply unit and the negative DC power supply unit in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit. the V-phase inverter unit generates an internal V-phase voltage having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of a V-phase of the predetermined zero-phase-containing unbalanced three-phase voltage from the predetermined DC voltage from the positive DC power supply unit and the negative DC power supply unit in accordance with a modulation signal; and and a W-phase inverter unit, wherein the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit are connected between the positive pole of the positive DC power supply unit and the negative pole of the negative DC power supply unit, and output the internal zero-phase-containing unbalanced three-phase voltage including the internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage as the U-phase voltage, the V-phase voltage, and the W-phase voltage, respectively, and the three-phase transformer device includes a single-phase U-phase transformer constituting the U-phase winding unit, a single-phase V-phase transformer constituting the V-phase winding unit, and a single-phase V-phase transformer constituting the W-phase winding unit. and a single-phase W-phase transformer connected to the three-phase four-wire inverter, wherein one end of a primary winding of the U-phase transformer, one end of a primary winding of the V-phase transformer, and one end of a primary winding of the W-phase transformer are connected in a Y-connection at a primary winding neutral point, and the secondary windings of the U-phase transformer, the secondary windings of the V-phase transformer, and the secondary windings of the W-phase transformer are connected in a Y-connection at the secondary winding neutral point, and the primary winding neutral point is connected to the power supply neutral point of the DC power supply, and the internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage from the three-phase four-wire inverter are respectivelyAn external zero-phase-sequence-containing unbalanced three-phase voltage that is input to the other end of the primary winding of the U-phase transformer, the other end of the primary winding of the V-phase transformer, and the other end of the primary winding of the W-phase transformer and that is obtained by converting the internal zero-phase-sequence-containing unbalanced three-phase voltage in accordance with a turns ratio may be output by the secondary winding of the U-phase transformer, the secondary winding of the V-phase transformer, the secondary winding of the W-phase transformer, and the secondary winding neutral point of the secondary windings that are Y-connected in the three-phase transformer unit.

[0025] According to this configuration, the three inverter units of the three-phase four-wire inverter are Y-connected at the power supply neutral point via a common positive DC power supply unit and a negative DC power supply unit, and the three Y-connected inverter units and the positive DC power supply and negative DC power supply unit are Y / Y-connected to the primary windings of the three single-phase transformers of the Y-connected three-phase transformer unit. As a result, the internal zero-phase-sequence-containing unbalanced three-phase voltages output from the three inverter units of the three-phase four-wire inverter are applied to the primary windings of the three single-phase transformers of the three-phase transformer unit, and a current of the zero-phase sequence component of the internal zero-phase-sequence-containing unbalanced three-phase voltage flows through a current path between the primary winding neutral point and the power supply neutral point. Furthermore, since the secondary windings of the single-phase transformers corresponding to the three phases are Y-connected, an external zero-phase-containing unbalanced three-phase voltage obtained by converting the internal zero-phase-containing unbalanced three-phase voltage in accordance with the turns ratio is output by the secondary windings and secondary winding neutral point of the Y-connected single-phase transformers corresponding to the three phases. As a result, it is possible to suitably construct a combination of a DC power supply, a three-phase inverter device, and a three-phase transformer device capable of outputting the zero-phase component of the external zero-phase-containing unbalanced three-phase voltage.

[0026] The DC power supply includes a positive DC power supply unit and a negative DC power supply unit that are connected in series with each other at a power supply neutral point and output the predetermined DC voltage, and the three-phase inverter device includes a U-phase inverter unit that generates an internal U-phase voltage having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of the U-phase of the predetermined zero-phase-containing unbalanced three-phase voltage from the predetermined DC voltages from the positive DC power supply unit and the negative DC power supply unit in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit; the V-phase inverter unit generates an internal V-phase voltage having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of the V-phase of the predetermined zero-phase-containing unbalanced three-phase voltage from the predetermined DC voltage from the positive DC power supply unit and the negative DC power supply unit in accordance with a W-phase pulse modulation signal from the pulse modulation signal generation circuit; and the W-phase inverter unit generates an internal W-phase voltage having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of the W-phase of the predetermined zero-phase-containing unbalanced three-phase voltage from the predetermined DC voltage from the positive DC power supply unit and the negative DC power supply unit in accordance with the W-phase pulse modulation signal from the pulse modulation signal generation circuit. a three-phase four-wire inverter unit, wherein the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit are connected between the positive pole of the positive DC power supply unit and the negative pole of the negative DC power supply unit, and outputs the internal zero-phase-containing unbalanced three-phase voltage including the internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage as the U-phase voltage, the V-phase voltage, and the W-phase voltage, respectively; and wherein the three-phase transformer device includes a three-phase five-legged core having a U-leg, a V-leg, a W-leg, and a pair of magnetic leakage legs, the U-phase winding unit provided in the U-phase leg, and a W-phase winding unit provided in the V-phase leg. a V-phase winding provided on the W-phase leg, and a three-phase five-leg core transformer, wherein one end of a primary winding of the U-phase winding, one end of a primary winding of the V-phase winding, and one end of a primary winding of the W-phase winding are connected in a Y-connection at a primary winding neutral point, and a secondary winding of the U-phase winding, a secondary winding of the V-phase winding, and a secondary winding of the W-phase winding are connected in a Y-connection at a secondary winding neutral point, and the primary winding neutral point is connected to the power supply neutral point of the DC power supply;and the internal W-phase voltage may be input to the other end of the primary winding of the U-phase winding section, the other end of the primary winding of the V-phase winding section, and the other end of the primary winding of the W-phase winding section, respectively, of the three-phase five-leg core transformer, and an external zero-phase-sequence-containing unbalanced three-phase voltage obtained by converting the internal zero-phase-sequence-containing unbalanced three-phase voltage in accordance with a turns ratio may be output by the Y-connected secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, the secondary winding of the W-phase winding section, and the secondary winding neutral point of the secondary winding of the secondary winding of the three-phase five-leg core transformer.

[0027] According to this configuration, the three inverter units of the three-phase four-wire inverter are Y-connected at the power supply neutral point via a common positive and negative DC power supply units, and the three Y-connected inverter units and the positive and negative DC power supply units are Y / Y-connected with the primary windings of the three winding units of the Y-connected three-phase five-leg core transformer. As a result, an internal zero-phase-sequence-containing unbalanced three-phase voltage output from the three inverter units of the three-phase four-wire inverter is applied to the primary windings of the three winding units of the three-phase five-leg core transformer, and a current of the zero-phase component of the internal zero-phase-sequence-containing unbalanced three-phase voltage flows through a current path between the primary winding neutral point and the power supply neutral point. Furthermore, a magnetic flux corresponding to the current of the zero-phase component flows through the magnetic leakage legs of the three-phase five-leg core. Furthermore, because the secondary windings of the three winding sections of the three-phase five-leg core transformer are Y-connected, an external zero-phase-containing unbalanced three-phase voltage obtained by converting the internal zero-phase-containing unbalanced three-phase voltage in accordance with the turns ratio is output by the secondary windings and secondary winding neutral point of the three Y-connected winding sections of the three-phase five-leg core transformer. As a result, it is possible to suitably construct a combination of a DC power supply, a three-phase inverter device, and a three-phase transformer device that can output the zero-phase component of the external zero-phase-containing unbalanced three-phase voltage.

[0028] Furthermore, an evaluation power supply according to another aspect of the present disclosure includes any one of the unbalanced three-phase power supply devices described above, wherein the DC power supply is a converter that converts the three-phase voltage of the power grid into a DC voltage, and the secondary side of the three-phase transformer is an output terminal to which the device under evaluation is connected.

[0029] According to this configuration, it is possible to evaluate the performance of the device under evaluation to cope with an unbalanced three-phase voltage including a zero-phase component in a test environment that can be easily constructed.

[0030] An unbalanced three-phase power supply device according to still another aspect of the present disclosure includes a current command generation unit that receives unbalanced three-phase current information including phase command values and amplitude command values for U-phase, V-phase, and W-phase of a zero-phase-containing unbalanced three-phase current that is an unbalanced three-phase current that includes a predetermined zero-phase component, and generates, based on the unbalanced three-phase current information, a U-phase current command, a V-phase current command, and a W-phase current command having phases, frequencies, and amplitudes of active components and reactive components that respectively correspond to the phase command values and amplitude command values for the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase current; a control circuit including a pulse modulation signal generation circuit that outputs a U-phase pulse modulation signal, a V-phase pulse modulation signal, and a W-phase pulse modulation signal corresponding to the U-phase current command, the V-phase current command, and the W-phase current command generated by the current command generation circuit; a DC power supply that outputs a predetermined DC voltage or DC current; a U-phase inverter unit, a V-phase inverter unit, and a W-phase inverter unit, wherein the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit respectively generate the U-phase pulse modulation signal, the V-phase pulse modulation signal, and the W-phase pulse modulation signal from the pulse modulation signal generation circuit. a three-phase inverter device that generates U-phase currents, V-phase currents, and W-phase currents having phases, frequencies, and amplitudes corresponding to U-phase, V-phase, and W-phase phase command values and active and reactive component amplitude command values of the predetermined zero-phase-containing unbalanced three-phase current, respectively, by using the predetermined DC voltage or DC current from the DC power source in accordance with the modulation signal and the W-phase pulse modulation signal, thereby outputting an internal zero-phase-containing unbalanced three-phase current including the U-phase current, the V-phase current, and the W-phase current; a three-phase transformer in which the secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, and the secondary winding of the W-phase winding section are Y-connected, the neutral point of the secondary windings is the neutral point of the Y-connection, and the U-phase current, the V-phase current, and the W-phase current of the internal zero-phase-containing unbalanced three-phase current from the three-phase inverter device are input to the primary winding of the U-phase winding section, the primary winding of the V-phase winding section, and the primary winding of the W-phase winding section, respectively; andThe three-phase transformer has various configurations and mutual connection relationships that enable it to output the zero-phase component of an external zero-phase-containing unbalanced three-phase current obtained by converting the internal zero-phase-containing unbalanced three-phase current in accordance with a turns ratio, and the external zero-phase-containing unbalanced three-phase current is output by the secondary winding of the U-phase winding unit, the secondary winding of the V-phase winding unit, the secondary winding of the W-phase winding unit, and the secondary winding neutral point, which are Y-connected in the three-phase transformer. Here, "turns ratio" refers to the ratio of the number of turns on the primary side to the number of turns on the secondary side in the three-phase transformer. "Pulse modulated signal" includes at least a PWM signal, a PAM signal, a PFM signal, a PPM signal, and a PDM signal.

[0031] According to this configuration, the current command generating unit generates a U-phase current command, a V-phase current command, and a W-phase current command having phases, frequencies, and amplitudes corresponding respectively to the phase command values of the U-phase, V-phase, and W-phase and the amplitude values of the active and reactive components of a predetermined zero-phase-containing unbalanced three-phase current input from outside.

[0032] Then, the pulse modulation signal generation circuit outputs a U-phase pulse modulation signal, a V-phase pulse modulation signal, and a W-phase pulse modulation signal corresponding to the U-phase current command, V-phase current command, and W-phase current command generated by the current command generation unit.

[0033] Then, the U-phase inverter unit, V-phase inverter unit, and W-phase inverter unit of the three-phase inverter device use a predetermined DC voltage or DC current from the DC power supply in accordance with the U-phase pulse modulated signal, V-phase pulse modulated signal, and W-phase pulse modulated signal from the pulse modulated signal generating circuit, respectively, to generate U-phase current, V-phase current, and W-phase current having phases, frequencies, and amplitudes corresponding respectively to the phase command values of the U-phase, V-phase, and W-phase and the amplitude command values of the active and reactive components of the predetermined zero-phase-containing unbalanced three-phase current, thereby outputting an internal zero-phase-containing unbalanced three-phase current consisting of the U-phase current, V-phase current, and W-phase current.

[0034] In the three-phase transformer, the U-phase current, V-phase current, and W-phase current of the internal zero-phase-containing unbalanced three-phase current from the three-phase inverter are input to the primary winding of the U-phase winding, the primary winding of the V-phase winding, and the primary winding of the W-phase winding, respectively. The DC power supply, the three-phase inverter, and the three-phase transformer have respective configurations and mutual connection relationships that enable them to output the zero-phase component of the external zero-phase-containing unbalanced three-phase current obtained by converting the internal zero-phase-containing unbalanced three-phase current in the three-phase transformer in accordance with the turns ratio, so that the external zero-phase-containing unbalanced three-phase current is output by the secondary winding of the U-phase winding, the secondary winding of the V-phase winding, the secondary winding of the W-phase winding, and the secondary winding neutral point, which are Y-connected in the three-phase transformer.

[0035] In other words, with the above configuration, the phase command values for the U, V, and W phases and the amplitude command values for the active and reactive components of the received predetermined zero-phase-containing unbalanced three-phase current are processed independently for each of the U, V, and W phases in the unbalanced three-phase power supply, thereby enabling the generation of an external zero-phase-containing unbalanced three-phase current corresponding to the predetermined zero-phase-containing unbalanced three-phase current. Furthermore, the DC power supply, the three-phase inverter, and the three-phase transformer have respective configurations and mutual connections that enable them to output the zero-phase component of the generated external zero-phase-containing unbalanced three-phase current, enabling the output of the zero-phase component of the external zero-phase-containing unbalanced three-phase current. Therefore, an unbalanced three-phase power supply can be provided that can output a desired zero-phase-containing unbalanced three-phase current by setting the desired zero-phase-containing three-phase unbalanced current to the predetermined zero-phase-containing unbalanced three-phase current. The unbalanced three-phase power supply generates an unbalanced three-phase current including a zero-sequence component using a three-phase inverter device, and therefore, by using the unbalanced three-phase power supply, it is possible to easily create a test environment that utilizes an unbalanced three-phase current including a zero-sequence component.

[0036] the main circuit includes a current sensor unit that detects currents of U-phase, V-phase, and W-phase of the internal zero-phase-containing unbalanced three-phase current or the external zero-phase-containing unbalanced three-phase current, the control circuit further includes a current feedback control unit, and the current command generation unit includes a phase command value generation unit that adds phase command values of the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase current to each of the U-phase, V-phase, and W-phase of a reference internal three-phase sine wave, respectively, and outputs a U-phase phase command value, a V-phase phase command value, and a W-phase phase command value obtained by the addition; a three-phase sine wave generating unit that compares the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value and their respective input timings with a sine table to generate a U-phase sine wave, a V-phase sine wave, and a W-phase sine wave having frequencies and reference amplitudes corresponding to the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value, respectively; and a three-phase sine wave generating unit that compares the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value and their respective input timings with a cos table to generate a U-phase sine wave, a V-phase sine wave, and a W-phase sine wave having frequencies and reference amplitudes corresponding to the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value, respectively. a three-phase cosine wave generator that generates a U-phase cosine wave, a V-phase cosine wave, and a W-phase cosine wave having phases, frequencies, and reference amplitudes corresponding to the U-phase cosine wave command value and the W-phase cosine wave command value, respectively; and a sine wave generator that determines the amplitudes of the U-phase sine wave, the V-phase cosine wave, and the W-phase cosine wave by multiplying the amplitude values of the U-phase sine wave, the V-phase cosine wave, and the W-phase sine wave generated by the three-phase sine wave generator by active component amplitude command values of the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase current, thereby generating a U-phase sine wave command, a V-phase sine wave command, and a W-phase sine wave command. a cosine wave amplitude determination unit that determines the amplitudes of the U-phase cosine wave, the V-phase cosine wave, and the W-phase cosine wave by multiplying the amplitude values of the U-phase cosine wave, the V-phase cosine wave, and the W-phase cosine wave generated by the cosine wave amplitude value generation unit by reactive amplitude command values of the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase current, thereby generating a U-phase cosine wave command, a V-phase cosine wave command, and a W-phase cosine wave command; and a cosine wave amplitude determination unit that determines the amplitudes of the U-phase cosine wave, the V-phase cosine wave, and the W-phase cosine wave by multiplying the amplitude values of the U-phase cosine wave, the V-phase cosine wave, and the W-phase cosine wave generated by the sine wave amplitude determination unit by reactive amplitude command values of the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase current, thereby generating a U-phase cosine wave command, a V-phase cosine wave command, and a W-phase cosine wave command,a current command amplitude determination unit that generates the U-phase current command, the V-phase current command, and the W-phase current command by adding the U-phase cosine wave command, the V-phase cosine wave command, and the W-phase cosine wave command generated by the cosine wave amplitude determination unit, and the current feedback control unit determines a U-phase current error, a V-phase current error, and a W-phase current command, which are errors in the U-phase, V-phase, and W-phase currents of the internal zero-sequence-containing unbalanced three-phase current or the external zero-sequence-containing unbalanced three-phase current detected by the current sensor unit with respect to the U-phase current command, the V-phase current command, and the W-phase current command generated by the current command amplitude determination unit. and a current compensation unit that generates a U-phase current manipulated variable, a V-phase current manipulated variable, and a W-phase current manipulated variable by applying compensation to the U-phase current error, the V-phase current error, and the W-phase current error generated by the current error generation unit, respectively, wherein the pulse modulation signal generation circuit is a circuit that generates the U-phase pulse modulation signal, the V-phase pulse modulation signal, and the W-phase pulse modulation signal that correspond to the U-phase current manipulated variable, the V-phase current manipulated variable, and the W-phase current manipulated variable generated by the current compensation unit, respectively.

[0037] This configuration allows for a suitable configuration for generating current commands and pulse-modulated signals. Furthermore, the U-, V-, and W-phase currents of the internal zero-sequence-containing unbalanced three-phase current are feedback-controlled, thereby providing a suitable external zero-sequence-containing unbalanced three-phase current.

[0038] The DC power supply includes a U-phase DC power supply unit, a V-phase DC power supply unit, and a W-phase DC power supply unit, each outputting the predetermined DC voltage or DC current, and the three-phase inverter device includes a single-phase U-phase inverter that configures the U-phase inverter unit and generates an internal U-phase current having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of the U-phase of the predetermined zero-phase-containing unbalanced three-phase current using the predetermined DC voltage or DC current from the U-phase DC power supply unit in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit, and a single-phase U-phase inverter that configures the V-phase inverter unit and generates an internal U-phase current having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of the U-phase of the predetermined zero-phase-containing unbalanced three-phase current. a single-phase V-phase inverter that generates an internal V-phase current having a phase, frequency, and amplitude corresponding to a V-phase phase command value and an amplitude command value of the predetermined zero-phase-containing unbalanced three-phase current by using the predetermined DC voltage or DC current from the V-phase DC power supply unit in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit; and a W-phase inverter unit that generates an internal V-phase current having a phase, frequency, and amplitude corresponding to a V-phase phase command value and an amplitude command value of the predetermined zero-phase-containing unbalanced three-phase current by using the predetermined DC voltage or DC current from the W-phase DC power supply unit in accordance with the W-phase pulse modulation signal from the pulse modulation signal generation circuit. a single-phase W-phase inverter that generates an internal W-phase current having a phase, frequency, and amplitude corresponding to the internal U-phase current, the internal V-phase current, and the internal W-phase current, and the U-phase inverter, the V-phase inverter, and the W-phase inverter output the internal zero-phase-containing unbalanced three-phase current including the internal U-phase current, the internal V-phase current, and the internal W-phase current as the U-phase current, the V-phase current, and the W-phase current, respectively; and the three-phase transformer device includes a single-phase U-phase transformer that configures the U-phase winding section, a single-phase V-phase transformer that configures the V-phase winding section, and a single-phase V-phase transformer that configures the W-phase winding section. a U-phase transformer and a W-phase transformer, wherein a secondary winding of the U-phase transformer, a secondary winding of the V-phase transformer, and a secondary winding of the W-phase transformer are connected in a Y-connection, and a neutral point of the Y-connection is the neutral point of the secondary winding, and the internal U-phase current, the internal V-phase current, and the internal W-phase current from the three-phase inverter unit are input to the primary winding of the U-phase transformer, the primary winding of the V-phase transformer, and the primary winding of the W-phase transformer, respectively, and an external zero-phase-sequence-containing unbalanced three-phase current obtained by converting the internal zero-phase-sequence-containing unbalanced three-phase current in accordance with a turns ratio isThe output may be from the secondary winding of the U-phase transformer, the secondary winding of the V-phase transformer, the secondary winding of the W-phase transformer, and the secondary winding neutral point of the secondary windings, which are connected in the Y-connection of the three-phase transformer unit.

[0039] According to this configuration, an internal zero-sequence-containing unbalanced three-phase current is generated in the main circuit. However, since the DC power supplies, the three inverter units of the three-phase inverter device, and the three winding units of the three-phase transformer device corresponding to the three phases are each configured as three DC power supply units of the DC power supply, three single-phase inverters of the three-phase inverter unit, and three single-phase transformers of the three-phase transformer unit, which are independent of each other, the zero-sequence component of the internal zero-sequence-containing unbalanced three-phase current flows through the primary windings of the DC power supply units, single-phase inverters, and single-phase transformers corresponding to each phase in accordance with the mutually unbalanced phase currents of the three phases. Furthermore, since the secondary windings of the single-phase transformers corresponding to the three phases are Y-connected, an external zero-sequence-containing unbalanced three-phase current, which is obtained by converting the internal zero-sequence-containing unbalanced three-phase current in accordance with the turns ratio, is output by the secondary windings and secondary winding neutral points of the single-phase transformers corresponding to the three Y-connected phases. As a result, it is possible to suitably construct a combination of a DC power supply, a three-phase inverter device, and a three-phase transformer device that can output the zero-phase component of an external zero-phase-containing unbalanced three-phase current.

[0040] the DC power supply comprises a U-phase DC power supply unit, a V-phase DC power supply unit, and a W-phase DC power supply unit, each outputting the predetermined DC voltage or DC current, and the three-phase inverter device comprises a single-phase U-phase inverter that configures the U-phase inverter unit and generates an internal U-phase current having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of the U-phase of the predetermined zero-phase-containing unbalanced three-phase current using the predetermined DC voltage or DC current from the U-phase DC power supply unit in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit, and a V-phase inverter that configures the V-phase inverter unit and a single-phase V-phase inverter configured to generate an internal V-phase current having a phase, frequency, and amplitude corresponding to a V-phase phase command value and an amplitude command value of the predetermined zero-phase-containing unbalanced three-phase current by using the predetermined DC voltage or DC current from the V-phase DC power supply unit in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit; and a W-phase inverter configured to generate an internal V-phase current having a phase, frequency, and amplitude corresponding to a V-phase phase command value and an amplitude command value of the predetermined zero-phase-containing unbalanced three-phase current by using the predetermined DC voltage or DC current from the W-phase DC power supply unit in accordance with the W-phase pulse modulation signal from the pulse modulation signal generation circuit. a single-phase W-phase inverter that generates an internal W-phase current having a phase, frequency, and amplitude corresponding to an amplitude command value, and the U-phase inverter, the V-phase inverter, and the W-phase inverter output the internal zero-sequence-containing unbalanced three-phase current including the internal U-phase current, the internal V-phase current, and the internal W-phase current as the U-phase current, the V-phase current, and the W-phase current, respectively, and the three-phase transformer device includes a three-phase five-legged core having a U-leg, a V-leg, a W-leg, and a pair of magnetic leakage legs, and the U-phase winding portion provided on the U-phase leg, a V-phase winding provided on the V-phase leg and a W-phase winding provided on the W-phase leg, wherein a secondary winding of the U-phase winding, a secondary winding of the V-phase winding, and a secondary winding of the W-phase winding are Y-connected, and a neutral point of the Y-connection is the neutral point of the secondary winding, and the internal U-phase current, the internal V-phase current, and the internal W-phase current from the three-phase inverter unit are input to a primary winding of the U-phase winding, a primary winding of the V-phase winding, and a primary winding of the W-phase winding of the three-phase five-leg core transformer, respectively; andAn external zero-phase-sequence-containing unbalanced three-phase current obtained by converting the internal zero-phase-sequence-containing unbalanced three-phase current in accordance with a turn ratio may be output by the secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, the secondary winding of the W-phase winding section, and the secondary winding neutral point of the secondary winding, which are Y-connected in the three-phase five-leg core transformer.

[0041] According to this configuration, an internal zero-phase-sequence-containing unbalanced three-phase current is generated in the main circuit. The DC power supplies, inverters, and windings corresponding to the three phases are respectively configured by independent DC power supplies, single-phase inverters, and phase windings of a three-phase five-leg core transformer. Therefore, the zero-phase component of the internal zero-phase-sequence-containing unbalanced three-phase current flows through the primary windings of the DC power supplies, single-phase inverters, and phase windings of the three-phase five-leg core transformer, respectively, in accordance with the unbalanced phase currents of the respective phases. Furthermore, magnetic flux corresponding to the zero-phase component flows through the magnetic leakage legs of the three-phase five-leg core. Furthermore, because the secondary windings of the three windings of the three-phase five-leg core transformer are Y-connected, the external zero-phase-sequence-containing unbalanced three-phase current, which is converted in accordance with the turns ratio, is output from the secondary windings and secondary winding neutral points of the three Y-connected windings of the three windings of the three-phase five-leg core transformer. As a result, it is possible to suitably construct a combination of a DC power supply, a three-phase inverter device, and a three-phase transformer device that can output the zero-phase component of an external zero-phase-containing unbalanced three-phase current.

[0042] the DC power supply includes a positive DC power supply unit and a negative DC power supply unit that are connected in series with each other at a power supply neutral point and that output the predetermined DC voltage or DC current, respectively, and the three-phase inverter device uses the predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit to generate an internal U-phase current having a phase, frequency, and amplitude that correspond to a phase command value and an amplitude command value of the U-phase of the predetermined zero-phase-containing unbalanced three-phase current; the V-phase inverter unit generates an internal V-phase current having a phase, frequency, and amplitude corresponding to a V-phase phase command value and an amplitude command value of the predetermined zero-phase-containing unbalanced three-phase current by using the predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit; and the three-phase inverter device generates an internal V-phase current having a phase, frequency, and amplitude corresponding to a V-phase phase command value and an amplitude command value of the predetermined zero-phase-containing unbalanced three-phase current by using the predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the W-phase pulse modulation signal from the pulse modulation signal generation circuit. a W-phase inverter unit that generates an internal W-phase current having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of a W-phase of a balanced three-phase current, wherein the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit are connected between a positive pole of the positive DC power supply unit and a negative pole of the negative DC power supply unit, and output the internal zero-phase-containing unbalanced three-phase current that includes the internal U-phase current, the internal V-phase current, and the internal W-phase current as the U-phase current, the V-phase current, and the W-phase current, respectively, a single-phase U-phase transformer constituting the V-phase winding section, a single-phase V-phase transformer constituting the W-phase winding section, one end of a primary winding of the U-phase transformer, one end of a primary winding of the V-phase transformer, and one end of a primary winding of the W-phase transformer are Y-connected at a primary winding neutral point, and a secondary winding of the U-phase transformer, a secondary winding of the V-phase transformer, and a secondary winding of the W-phase transformer are Y-connected at the secondary winding neutral point, and the primary winding neutral point is connected to the power supply neutral point of the DC power supply,The internal U-phase current, the internal V-phase current, and the internal W-phase current from the three-phase four-wire inverter may be input to a primary winding of the U-phase transformer, a primary winding of the V-phase transformer, and a primary winding of the W-phase transformer, respectively, and an external zero-phase-containing unbalanced three-phase current obtained by converting the internal zero-phase-containing unbalanced three-phase current in accordance with a turns ratio may be output by a secondary winding of the U-phase transformer, a secondary winding of the V-phase transformer, a secondary winding of the W-phase transformer, and a secondary winding neutral point of the secondary windings, which are Y-connected in the three-phase transformer unit.

[0043] According to this configuration, the three inverter units of the three-phase four-wire inverter are Y-connected at the power supply neutral point via a common positive DC power supply unit and a negative DC power supply unit, and the three Y-connected inverter units and the positive DC power supply unit and the negative DC power supply unit are Y / Y-connected to the primary windings of the three single-phase transformers of the Y-connected three-phase transformer unit. As a result, internal zero-phase-sequence-containing unbalanced three-phase currents output from the three inverter units of the three-phase four-wire inverter are input to the primary windings of the three single-phase transformers of the three-phase transformer unit, and a current of the zero-phase sequence component of the internal zero-phase-sequence-containing unbalanced three-phase current flows through a current path between the primary winding neutral point and the power supply neutral point. Furthermore, since the secondary windings of the single-phase transformers corresponding to the three phases are Y-connected, an external zero-phase-containing unbalanced three-phase current obtained by converting the internal zero-phase-containing unbalanced three-phase current in accordance with the turns ratio is output by the secondary windings and secondary winding neutral points of the Y-connected single-phase transformers corresponding to the three phases. As a result, it is possible to suitably construct a combination of a DC power supply, a three-phase inverter device, and a three-phase transformer device capable of outputting the zero-phase component of the external zero-phase-containing unbalanced three-phase current.

[0044] The DC power supply includes a positive DC power supply unit and a negative DC power supply unit which are connected in series with each other at a power supply neutral point and which respectively output the predetermined DC voltage or DC current, and the three-phase inverter device includes a U-phase inverter unit which generates an internal U-phase current having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of a U-phase of the predetermined zero-phase-containing unbalanced three-phase current, using the predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit; the V-phase inverter unit generates an internal V-phase current having a phase, frequency, and amplitude corresponding to a V-phase phase command value and an amplitude command value of the predetermined zero-phase-containing unbalanced three-phase current by using the predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit; and the three-phase inverter unit generates an internal V-phase current having a phase, frequency, and amplitude corresponding to a V-phase phase command value and an amplitude command value of the predetermined zero-phase-containing unbalanced three-phase current by using the predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the W-phase pulse modulation signal from the pulse modulation signal generation circuit. and a W-phase inverter unit that generates an internal W-phase current having a phase, frequency, and amplitude corresponding to a phase command value and an amplitude command value of a W-phase of the predetermined zero-phase-containing unbalanced three-phase current, wherein the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit are connected between a positive pole of the positive DC power supply unit and a negative pole of the negative DC power supply unit, and output the internal zero-phase-containing unbalanced three-phase current including the internal U-phase current, the internal V-phase current, and the internal W-phase current as the U-phase current, the V-phase current, and the W-phase current, respectively. the three-phase transformer device comprises a three-phase five-legged core having a U-leg, a V-leg, a W-leg, and a pair of magnetic leakage legs, the U-phase winding section provided on the U-phase leg, the V-phase winding section provided on the V-phase leg, and the W-phase winding section provided on the W-phase leg, one end of a primary winding of the U-phase winding section, one end of a primary winding of the V-phase winding section, and one end of a primary winding of the W-phase winding section are Y-connected at a neutral point of the primary winding, and the secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, and the secondary winding of the W-phase winding section are Y-connected at the neutral point of the secondary winding,The three-phase five-leg core transformer may have a primary winding neutral point connected to the power supply neutral point of the DC power supply, wherein the internal U-phase current, the internal V-phase current, and the internal W-phase current from the three-phase four-wire inverter are input to a primary winding of the U-phase winding section, a primary winding of the V-phase winding section, and a primary winding of the W-phase winding section of the three-phase five-leg core transformer, respectively, and an external zero-phase-containing unbalanced three-phase current obtained by converting the internal zero-phase-containing unbalanced three-phase current in accordance with a turns ratio is output by a secondary winding of the U-phase winding section, a secondary winding of the V-phase winding section, a secondary winding of the W-phase winding section, and the secondary winding neutral point of the secondary winding, which are Y-connected of the three-phase five-leg core transformer.

[0045] According to this configuration, the three inverter units of the three-phase four-wire inverter are Y-connected at the power supply neutral point via a common positive and negative DC power supply units, and the three Y-connected inverter units and the positive and negative DC power supply units are Y / Y-connected with the primary windings of the three winding units of the Y-connected three-phase five-leg core transformer. As a result, internal zero-phase-sequence-containing unbalanced three-phase currents output from the three inverter units of the three-phase four-wire inverter are input to the primary windings of the three winding units of the three-phase five-leg core transformer, and a zero-phase-sequence component current of the internal zero-phase-sequence-containing unbalanced three-phase current flows through a current path between the primary winding neutral point and the power supply neutral point. Furthermore, a magnetic flux corresponding to the zero-phase-sequence component current flows through the magnetic leakage legs of the three-phase five-leg core. Furthermore, because the secondary windings of the three winding sections of the three-phase five-leg core transformer are Y-connected, an external zero-phase-containing unbalanced three-phase current obtained by converting the internal zero-phase-containing unbalanced three-phase current in accordance with the turns ratio is output by the secondary windings and secondary winding neutral point of the three Y-connected winding sections of the three-phase five-leg core transformer. As a result, it is possible to suitably construct a combination of a DC power supply, a three-phase inverter device, and a three-phase transformer device that can output the zero-phase component of the external zero-phase-containing unbalanced three-phase current.

[0046] Furthermore, an evaluation power supply according to another aspect of the present disclosure includes any of the unbalanced three-phase power supply devices described above, wherein the DC power supply is a converter that converts a three-phase voltage or three-phase current of a power system into a DC voltage or DC current, and the secondary side of the three-phase transformer is an output terminal to which the device under evaluation is connected.

[0047] According to this configuration, it is possible to evaluate the performance of the device under evaluation to cope with an unbalanced three-phase voltage including a zero-phase component in a test environment that can be easily constructed.

[0048] Specific embodiments of the present disclosure will be described below with reference to the drawings. Note that, hereinafter, identical or corresponding elements throughout the drawings will be designated by the same reference numerals, and redundant descriptions thereof will be omitted. Furthermore, since the following drawings are for explaining the present disclosure, elements unrelated to the present disclosure may be omitted, dimensions may be inaccurate due to exaggeration or simplification, shapes of corresponding elements may not match in multiple drawings, and waveforms of signals, etc. may be inaccurate. Furthermore, the present disclosure is not limited to the following embodiments.

[0049] (Unbalanced three-phase electrical vector including zero-sequence component) First, we will explain unbalanced three-phase electric quantity vectors including zero-sequence components that are handled in this disclosure. In this specification, "electric quantity" is a concept that includes "voltage" and "current." "Zero-sequence" refers to the zero-sequence component in the symmetric coordinate system. In other words, it means "a three-phase electric quantity vector that is unbalanced and whose sum is not zero."

[0050] FIG. 7 is an explanatory diagram for explaining unbalanced three-phase electric quantity vectors including zero-phase components. Referring to FIG. 7, a waveform diagram is shown in the upper part. This waveform diagram shows the waveforms of three-phase electric quantities including zero-phase components. In this waveform diagram, the amplitude of the electric quantity of each phase is such that, when the amplitude of the U-phase electric quantity is 100%, the amplitude of the V-phase electric quantity is 50%, and the amplitude of the W-phase electric quantity is 50%. The phase difference between the electric quantities of the three phases is 120°.

[0051] The electrical quantities represented by these three waveforms can be expressed as vectors, as shown in the vector diagram on the lower left of Figure 7. If the U-phase vector, V-phase vector, and W-phase vector of this vector diagram are resolved and translated to find the sum of the U-phase vector, V-phase vector, and W-phase vector, a provisional balanced vector whose sum is zero and the remaining vector of the U-phase vector are obtained, as shown in the diagram on the lower right of Figure 7. The vector obtained by dividing this remaining vector into three equal parts is defined as the "zero sequence."

[0052] For example, an unbalanced three-phase voltage vector including a zero-sequence component can be expressed by the following equation using the symmetric coordinate method.

[0053]

number

[0054] (Points of focus and features of the present invention) The present invention addresses the problem of using a conventional method for testing a distributed power system to evaluate its ability to continue operation during a power sag, in which a voltage or current containing a zero-phase component is supplied by artificially short-circuiting or grounding a distribution line. During extensive research into this problem, the inventors of the present invention focused on the fact that a three-phase sine wave is conventionally generated when DC is converted to AC by an inverter.

[0055] Generally, such a three-phase sine wave is generated by pulse-width modulating a reference sine wave, which is a modulated signal for each phase, to generate a PWM signal for each phase, and then inputting this PWM signal to a three-phase inverter. However, a typical inverter cannot output the zero-phase component of a three-phase sine wave for the following reasons.

[0056] Conventional inverters are not designed to output zero-phase components that occur during ground faults or other events. Therefore, the reference sine wave of one of the three phases is generated from the reference sine waves of the other two. Specifically, as can be seen from the vector diagram in the lower left of Figure 7, if there is no zero-phase component, the sum of the three-phase sine wave vectors is zero. Using this relationship, the reference sine wave (phase vector) of one of the three phases is generated by adding the remaining two reference sine waves (phase vectors) and inverting the resulting sine wave. For example, if the V-phase vector is the one of the phase vectors, then U-phase vector + V-phase vector + W-phase vector = 0, and therefore V-phase vector = -(U-phase vector + W-phase vector). Therefore, conventional inverters cannot output the zero-phase component of a three-phase sine wave.

[0057] When a three-phase sine wave is feedback-controlled or feedforward-controlled, a voltage command or current command (sine wave signal) corresponding to a reference sine wave is generated, and a manipulated variable PWM signal is generated by pulse-width modulating the manipulated variable (sine wave signal) based on the command, and this manipulated variable PWM signal is input to an inverter, and the above-mentioned circumstances also apply in this case. In addition, the above-mentioned pulse-modulated signal can generally be used as a signal for controlling the inverter to generate the reference sine wave.

[0058] Therefore, the inventors of the present invention have conceived of generating voltage commands or current commands for U-phase, V-phase, and W-phase corresponding to an unbalanced three-phase sine wave containing a predetermined zero-phase component, inputting an operation amount pulse modulation signal based on the voltage commands or current commands for U-phase, V-phase, and W-phase to a three-phase inverter device, and outputting a zero-phase-containing unbalanced three-phase sine wave corresponding to the unbalanced three-phase sine wave containing the predetermined zero-phase component from the three-phase inverter device.

[0059] However, commonly used three-phase, three-wire inverters and core-type, three-phase, three-limbed transformers cannot output the zero-phase component of a three-phase sine wave because there is no path for transmitting the zero-phase component of a three-phase sine wave. Therefore, the inventors of the present invention have identified the respective configurations and mutual connection relationships of a DC power supply, a three-phase inverter device, and a three-phase transformer device that are capable of outputting the zero-phase component of a three-phase sine wave. The features thus conceived and identified are the characteristics of the present invention.

[0060] (Unity of invention and unity of application) The unbalanced three-phase power supply device disclosed herein includes: an electrical quantity command generating unit that generates electrical quantity commands for U-phase, V-phase, and W-phase of predetermined zero-phase-containing unbalanced three-phase electrical quantities; a pulse modulation signal generating circuit that outputs a U-phase pulse modulation signal, a V-phase pulse modulation signal, and a W-phase pulse modulation signal corresponding to the electrical quantity commands for the U-phase, V-phase, and W-phase; a DC power supply; a three-phase inverter device that outputs internal zero-phase-containing unbalanced three-phase voltages including U-phase electrical quantities, V-phase electrical quantities, and W-phase electrical quantities that correspond respectively to the electrical quantity commands for the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase electrical quantities using a DC voltage or DC current from the DC power supply in accordance with the U-phase pulse modulation signal, the V-phase pulse modulation signal, and the W-phase pulse modulation signal; and a three-phase transformer that converts the internal zero-phase-containing unbalanced three-phase electrical quantities into external zero-phase-containing unbalanced three-phase electrical quantities in accordance with a turns ratio, and outputs the external zero-phase-containing unbalanced three-phase electrical quantities from a Y-connected secondary side.

[0061] In the following, an unbalanced three-phase power supply that handles voltage, which is an electrical quantity, is exemplified in embodiment 1, and an unbalanced three-phase power supply that handles current, which is an electrical quantity, is exemplified in embodiment 3. The voltage command generation unit, pulse modulated signal generation circuit, DC power supply, three-phase inverter device, and three-phase transformer of the unbalanced three-phase power supply of embodiment 1 and the current command generation unit, pulse modulated signal generation circuit, DC power supply, three-phase inverter device, and three-phase transformer of embodiment 3 have similar configurations.

[0062] Therefore, the invention relating to the unbalanced three-phase power supply device of embodiment 1 and the invention relating to the unbalanced three-phase power supply device of embodiment 3 have unity of invention and unity of application.

[0063] (Embodiment 1)

[0064] [Outline of the structure] Fig. 1 is a functional block diagram showing an example of the configuration of an unbalanced three-phase power supply 100 according to a first embodiment of the present disclosure. Referring to Fig. 1, the unbalanced three-phase power supply 100 includes a control circuit 1A and a main circuit 2A. The control circuit 1A includes a voltage command generation unit 3 and a pulse modulation signal generation circuit 4. The main circuit 2A includes a direct current power supply DC, a three-phase inverter device INV, and a three-phase transformer device T.

[0065] The voltage command generating unit 3 receives unbalanced three-phase voltage information IFubv including a U-phase phase command value Cphu, a V-phase phase command value Cphv, and a W-phase phase command value Cphw of a zero-phase-containing unbalanced three-phase voltage that is an unbalanced three-phase voltage that includes a predetermined zero-phase component, as well as a U-phase amplitude command value Camu, a V-phase amplitude command value Camv, and a W-phase amplitude command value Camw, and generates a U-phase voltage command Cvu, a V-phase voltage command Cvv, and a W-phase voltage command Cvw having phases, frequencies, and amplitudes corresponding to the U-phase phase command value Cphu, the V-phase phase command value Cphv, and the W-phase phase command value Cphw of the predetermined zero-phase-containing unbalanced three-phase voltage, as well as the U-phase amplitude command value Camu, the V-phase amplitude command value Camv, and the W-phase amplitude command value Camw, respectively, based on the unbalanced three-phase voltage information IFubv.

[0066] The pulse modulation signal generation circuit 4 outputs a U-phase pulse modulation signal Spu, a V-phase pulse modulation signal Spv, and a W-phase pulse modulation signal Spw corresponding to the U-phase voltage command Cvu, the V-phase voltage command Cvv, and the W-phase voltage command Cvw generated by the voltage command generation unit 3.

[0067] The direct current power supply DC outputs a predetermined direct current voltage.

[0068] The three-phase inverter device INV includes a U-phase inverter section INVu (see FIG. 2), a V-phase inverter section INVv (see FIG. 2), and a W-phase inverter section INVw (see FIG. 2). The U-phase inverter section INVu, the V-phase inverter section INVv, and the W-phase inverter section INVw generate predetermined zero-phase-containing pulses from a predetermined DC voltage from a DC power supply DC in accordance with a U-phase pulse modulation signal Spu, a V-phase pulse modulation signal Spv, and a W-phase pulse modulation signal Spw from a pulse modulation signal generation circuit 4, respectively. An internal U-phase voltage Viu, an internal V-phase voltage Viv, and an internal W-phase voltage Viw are generated, having phases, frequencies, and amplitudes corresponding to the U-phase phase command value Cphu, the V-phase phase command value Cphv, and the W-phase phase command value Cphw of the unbalanced three-phase voltage, and the U-phase amplitude command value Camu, the V-phase amplitude command value Camv, and the W-phase amplitude command value Camw, respectively, and thereby an internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi including the internal U-phase voltage Viu, the internal V-phase voltage Viv, and the internal W-phase voltage Viw is output.

[0069] The three-phase transformer device T includes a U-phase winding section Tu (see FIG. 2), a V-phase winding section Tv (see FIG. 2), a W-phase winding section Tw (see FIG. 2), and a secondary winding neutral point Ns (see FIG. 2). The secondary winding Wus (see FIG. 2) of the U-phase winding section Tu, the secondary winding Wvs (see FIG. 2) of the V-phase winding section Tv, and the secondary winding Wws (see FIG. 2) of the W-phase winding section Tw are Y-connected, and the secondary winding neutral point Ns is the neutral point of the Y-connection. The internal U-phase voltage Viu, internal V-phase voltage Viv, and internal W-phase voltage Viw of the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi from the three-phase inverter device INV are input to the primary winding Wuf (see FIG. 2) of the U-phase winding section Tu, the primary winding Wvf (see FIG. 2) of the V-phase winding section Tv, and the primary winding Wwf (see FIG. 2) of the W-phase winding section Tw, respectively.

[0070] The DC power supply DC of the main circuit 2A, the three-phase inverter device INV, and the three-phase transformer device T have respective configurations and mutual connection relationships that enable them to output the zero-phase component of the external zero-phase-containing unbalanced three-phase voltage Vubo, which is obtained by converting the internal zero-phase-containing unbalanced three-phase voltage Vubi in the three-phase transformer device T in accordance with the turns ratio of the three-phase transformer device T. The external zero-phase-containing unbalanced three-phase voltage Vubo is output by the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, the secondary winding Wws of the W-phase winding section Tw, and the secondary winding neutral point Ns, which are Y-connected in the three-phase transformer device T. The external zero-sequence-containing unbalanced three-phase voltage Vubo includes an external U-phase voltage Vou, an external V-phase voltage Vov, and an external W-phase voltage Vow, which are obtained by converting the internal U-phase voltage Viu, the internal V-phase voltage Viv, and the internal W-phase voltage Viw of the internal zero-sequence-containing unbalanced three-phase voltage Vubi according to the turns ratio.

[0071] The control of the internal zero-sequence-containing unbalanced three-phase voltage Vubi or the external zero-sequence-containing unbalanced three-phase voltage Vubo may be either feedforward control or feedback control. The configuration when feedforward control is performed is roughly as described above.

[0072] When feedback control is performed, a voltage feedback control unit 5 (see FIG. 6 ) is provided in the control circuit 1A between the voltage command generation unit 3 and the pulse modulation signal generation circuit 4. The voltage feedback control unit 5 generates a U-phase voltage control variable Ovu, a V-phase voltage control variable Ovv, and a W-phase voltage control variable Ovw based on errors of the internal U-phase voltage Viu, the internal V-phase voltage Viv, and the internal W-phase voltage Viw of the internal zero-sequence-containing unbalanced three-phase voltage Vubi relative to the U-phase voltage command Cvu, the V-phase voltage command Cvv, and the W-phase voltage command Cvw from the voltage command generation unit 3, or generates a U-phase voltage control variable Ovu, a V-phase voltage control variable Ovv, and a W-phase voltage control variable Ovw based on errors of the external U-phase voltage Vou, the external V-phase voltage Vov, and the external W-phase voltage Vow of the external zero-sequence-containing unbalanced three-phase voltage Vubo relative to the U-phase voltage command Cvu, the V-phase voltage command Cvv, and the W-phase voltage command Cvw from the voltage command generation unit 3. The pulse modulation signal generation circuit 4 outputs a U-phase pulse modulation signal Spu, a V-phase pulse modulation signal Spv, and a W-phase pulse modulation signal Spw, which correspond to the U-phase voltage control amount Ovu, the V-phase voltage control amount Ovv, and the W-phase voltage control amount Ovw, which are generated by the voltage feedback control unit 5.

[0073] [Advanced Configuration] The detailed configuration of the unbalanced three-phase power supply device 100 will be described below, starting with the main circuit 2A and then the control circuit 1A. A circuit configuration in which the pulse modulation signal is a PWM signal will be exemplified below. A circuit configuration in which the pulse modulation signal is a pulse modulation signal other than a PWM signal can also be constructed by replacing the circuit for generating the PWM signal shown in pulse modulation signal generation circuit 4 in FIG. 6 with a circuit for generating a pulse modulation signal other than a PWM signal. In the following, a PWM signal will be referred to as a pulse modulation signal, which is a broader concept.

[0074] {Main circuit 2A} 2 to 5, the main circuit 2A requires that "the DC power source DC, the three-phase inverter INV, and the three-phase transformer T have respective configurations and mutual connection relationships that enable them to output the zero-phase component of the external zero-phase-sequence-containing unbalanced three-phase voltage Vubo obtained by converting the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi in the three-phase transformer T in accordance with the turns ratio of the three-phase transformer T." Hereinafter, this requirement will be referred to as the "zero-phase-sequence-output requirement." The zero-phase-sequence-output requirement includes the following four items:

[0075] a. Each phase can be controlled individually, and the main circuits of each phase are independent (this does not mean that they are isolated).

[0076] b. The transformer is independent or has a shell-type five-legged core.

[0077] c. In the transformer, at least the secondary side is Y-connected and has a neutral point (a typical Y / Y connection requires a △ winding to suppress third harmonics, but this is not necessary in this case).

[0078] The following four types of circuit configurations were identified as realistic circuit configurations that satisfy this requirement for zero-phase output capability.

[0079] First zero-phase output configuration: 3 single-phase inverters + 3 single-phase transformers Second zero-phase output configuration: Three single-phase inverters + one three-phase five-legged transformer Third zero-phase output configuration: one three-phase four-wire inverter + three single-phase transformers Fourth zero-phase output configuration: one three-phase four-wire inverter + one three-phase five-leg core transformer Here, please note the following. As is clear from the above-mentioned "zero-phase output capability requirement," the first to fourth zero-phase output configurations specify only combinations of a direct-current power supply DC, a three-phase inverter INV, and a three-phase transformer T. Meanwhile, FIGS. 2 to 5, which are used to explain the first to fourth zero-phase output configurations, show low-pass filters Flu, Flv, Flw, and a voltage sensor unit SEv in addition to the direct-current power supply DC, the three-phase inverter INV, and the three-phase transformer T. However, the low-pass filters Flu, Flv, Flw, and the voltage sensor unit SEv are elements unrelated to the "zero-phase output capability requirement," and are not included in the first to fourth zero-phase output configurations.

[0080] The low-pass filters Flu, Flv, and Flw are provided to remove the carrier frequency component of the pulse modulated signal from the voltage (internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi or external zero-phase-sequence-containing unbalanced three-phase voltage Vubo) output from the three-phase inverter INV. Each of the low-pass filters Flu, Flv, and Flw is composed of a reactor and a capacitor arranged on the output side of the reactor. Generally, the reactor is arranged on the primary side of the three-phase transformer T, and the capacitor is arranged on the primary or secondary side of the three-phase transformer T. A configuration in which the capacitor is arranged on the primary side of the three-phase transformer T is called "primary-side control," and a configuration in which the capacitor is arranged on the secondary side of the three-phase transformer T is called "secondary-side control." However, if the three-phase transformer T is composed of a leakage transformer, the reactor is omitted and the capacitor is arranged on the secondary side of the three-phase transformer T, resulting in "secondary-side control."

[0081] The control target of the "primary side control" and "secondary side control" is the voltage output from the three-phase inverter device INV (the internal zero-phase-containing unbalanced three-phase voltage Vubi or the external zero-phase-containing unbalanced three-phase voltage Vubo). Therefore, in the case of "primary side control," the voltage sensor unit SEv is provided on the output side of the capacitor of the low-pass filter on the primary side of the three-phase transformer device T to detect the internal zero-phase-containing unbalanced three-phase voltage Vubi, and in the case of "secondary side control," the voltage sensor unit SEv is provided on the output side of the capacitor of the low-pass filter on the secondary side of the three-phase transformer device T to detect the external zero-phase-containing unbalanced three-phase voltage Vubo.

[0082] The main circuit 2A including each of the first to fourth zero-phase output configurations will be described below in order.

[0083] <Main circuit 2A including the first zero-phase output configuration> Fig. 2 is a circuit diagram showing details of the main circuit 2A including the first zero-phase output configuration in Fig. 1. Hereinafter, the contents of the main circuit 2A including the first zero-phase output configuration will be described with reference to Fig. 2.

[0084] <DC power supply DC> The DC power supply DC includes a U-phase DC power supply unit DCu, a V-phase DC power supply unit DCv, and a W-phase DC power supply unit DCw, each of which outputs a predetermined DC voltage. Here, the U-phase DC power supply unit DCu, the V-phase DC power supply unit DCv, and the W-phase DC power supply unit DCw are connected in parallel with each other, but may be independent of each other. The U-phase DC power supply unit DCu, the V-phase DC power supply unit DCv, and the W-phase DC power supply unit DCw may be any DC voltage source capable of outputting a predetermined DC voltage, and are not particularly limited thereto. Examples of the U-phase DC power supply unit DCu, the V-phase DC power supply unit DCv, and the W-phase DC power supply unit DCw include a capacitor, a DC / DC converter, a rectifier, and a rechargeable battery. Here, the U-phase DC power supply unit DCu, the V-phase DC power supply unit DCv, and the W-phase DC power supply unit DCw are each composed of a capacitor. In this case, a DC power supply unit (not shown) is provided upstream of these three capacitors to charge the three capacitors.

[0085] <Three-phase inverter INV> The three-phase inverter device INV includes a U-phase inverter section INVu, a V-phase inverter section INVv, and a W-phase inverter section INVw. The three-phase inverter device INV is configured with a three-phase inverter unit. The three-phase inverter unit includes a single-phase U-phase inverter that constitutes the U-phase inverter section INVu, a single-phase V-phase inverter that constitutes the V-phase inverter section INVv, and a single-phase W-phase inverter that constitutes the W-phase inverter section INVw. The single-phase U-phase inverter, the single-phase V-phase inverter, and the single-phase W-phase inverter are not particularly limited as long as they can convert DC voltage to AC voltage. The single-phase U-phase inverter, the single-phase V-phase inverter, and the single-phase W-phase inverter are each configured with, for example, a full-bridge inverter. Full-bridge inverters are well known, so they will be briefly described below.

[0086] The U-phase inverter has four switching elements Q1u to Q4u connected in a full bridge. The input terminal of the U-phase inverter is connected to a U-phase DC power supply unit DCu. A U-phase positive phase pulse modulated signal Spup constituting the U-phase pulse modulated signal Spu from the pulse modulated signal generation circuit 4 is input to the pair of switching element Q1u and switching element Q2u, and a U-phase opposite phase pulse modulated signal Spuo constituting the U-phase pulse modulated signal Spu from the pulse modulated signal generation circuit 4 is input to the pair of switching element Q3u and switching element Q4u. The U-phase inverter alternately turns on and off a pair of switching elements Q1u and Q2u in accordance with a U-phase positive-phase pulse modulation signal Spup and a pair of switching elements Q3u and Q4u in accordance with a U-phase negative-phase pulse modulation signal Spuo, thereby generating, from a predetermined DC voltage from the U-phase DC power supply unit DCu, an internal U-phase voltage Viu having a phase, frequency, and amplitude corresponding to a U-phase phase command value Cphu and an amplitude command value Camu of a predetermined zero-phase-containing unbalanced three-phase voltage, and outputs the internal U-phase voltage Viu from the output terminal.

[0087] The V-phase inverter has four switching elements Q1v to Q4v connected in a full bridge. The input terminal of the V-phase inverter is connected to a V-phase DC power supply unit DCv. A V-phase positive-phase pulse modulated signal Spvp that constitutes a V-phase pulse modulated signal Spv from the pulse modulated signal generation circuit 4 is input to the pair of switching element Q1v and switching element Q2v, and a V-phase negative-phase pulse modulated signal Spvo that constitutes a V-phase pulse modulated signal Spv from the pulse modulated signal generation circuit 4 is input to the pair of switching element Q3v and switching element Q4v. The V-phase inverter alternately turns on and off a pair of switching elements Q1v and Q2v in accordance with a V-phase positive-phase pulse modulation signal Spvp and a pair of switching elements Q3v and Q4v in accordance with a V-phase negative-phase pulse modulation signal Spvo, thereby generating, from a predetermined DC voltage from a V-phase DC power supply unit DCv, an internal V-phase voltage Viv having a phase, frequency, and amplitude corresponding to a V-phase phase command value Cphv and an amplitude command value Camv of a predetermined zero-phase-containing unbalanced three-phase voltage, and outputs the internal V-phase voltage Viv from an output terminal.

[0088] The W-phase inverter has four switching elements Q1w to Q4w connected in a full bridge. The input terminal of the W-phase inverter is connected to a W-phase DC power supply unit DCw. A W-phase positive-phase pulse modulated signal Spwp constituting the W-phase pulse modulated signal Spw from the pulse modulated signal generation circuit 4 is input to the pair of switching element Q1w and switching element Q2w, and a W-phase negative-phase pulse modulated signal Spwo constituting the W-phase pulse modulated signal Spw from the pulse modulated signal generation circuit 4 is input to the pair of switching element Q3w and switching element Q4w. The W-phase inverter alternately turns on and off a pair of switching elements Q1w and Q2w in accordance with the W-phase positive-phase pulse modulation signal Spwp and a pair of switching elements Q3w and Q4w in accordance with the W-phase negative-phase pulse modulation signal Spwo, thereby generating, from a predetermined DC voltage from the W-phase DC power supply unit DCw, an internal W-phase voltage Viw having a phase, frequency, and amplitude corresponding to a W-phase phase command value Cphw and an amplitude command value Camw of a predetermined zero-phase-containing unbalanced three-phase voltage, and outputs the internal W-phase voltage Viw from an output terminal.

[0089] In this way, the U-phase inverter, the V-phase inverter, and the W-phase inverter output an internal zero-phase-containing unbalanced three-phase voltage Vubi that includes the internal U-phase voltage Viu, the internal V-phase voltage Viv, and the internal W-phase voltage Viw as the U-phase voltage, the V-phase voltage, and the W-phase voltage, respectively.

[0090] <Three-phase transformer T> The three-phase transformer device T includes a U-phase winding section Tu, a V-phase winding section Tv, and a W-phase winding section Tw. The U-phase winding section Tu, the V-phase winding section Tv, and the W-phase winding section Tw have a common predetermined turns ratio. This also applies to the second to fourth zero-phase output configurations.

[0091] The three-phase transformer device T is composed of a three-phase transformer unit. The three-phase transformer unit includes a single-phase U-phase transformer that constitutes the U-phase winding section Tu, a single-phase V-phase transformer that constitutes the V-phase winding section Tv, and a single-phase W-phase transformer that constitutes the W-phase winding section.

[0092] The primary winding Wuf of the U-phase transformer is connected to the output terminal of the U-phase inverter via a low-pass filter Flu. The primary winding Wvf of the V-phase transformer is connected to the output terminal of the V-phase inverter via a low-pass filter Flv. The primary winding Wwf of the W-phase transformer is connected to the output terminal of the W-phase inverter via a low-pass filter Flw.

[0093] The secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, and the secondary winding Wws of the W-phase transformer are star-connected at the secondary winding neutral point Ns.

[0094] In the three-phase transformer unit, the internal U-phase voltage Viu, internal V-phase voltage Viv, and internal W-phase voltage Viw of the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi from the three-phase inverter unit are input to the primary winding Wuf of the U-phase transformer, the primary winding Wvf of the V-phase transformer, and the primary winding Wwf of the W-phase transformer, respectively. The internal U-phase voltage Viu, internal V-phase voltage Viv, and internal W-phase voltage Viw are converted in the secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, and the secondary winding Wws of the W-phase transformer according to a predetermined turns ratio to generate an external zero-phase-sequence-containing unbalanced three-phase voltage Vubo including an external U-phase voltage Vou, an external V-phase voltage Vov, and an external W-phase voltage Vow. This external zero-phase-sequence-containing unbalanced three-phase voltage Vubo is output by the secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, the secondary winding Wws of the W-phase transformer, and the secondary winding neutral point Ns, which are all connected in a Y-connection in the three-phase transformer unit. Reference symbols U, V, W, and n denote the U-phase, V-phase, W-phase, and zero-phase output terminals on the secondary side of the three-phase transformer unit, respectively.

[0095] <Elements other than the first zero-phase output configuration> *Low pass filter* Here, the low-pass filters are configured in a "primary side control" configuration. A U-phase low-pass filter Flu is arranged between the output terminal of the U-phase inverter and the primary winding Wuf of the U-phase transformer. A V-phase low-pass filter Flv is arranged between the output terminal of the V-phase inverter and the primary winding Wvf of the V-phase transformer. A W-phase low-pass filter Flw is arranged between the output terminal of the W-phase inverter and the primary winding Wwf of the W-phase transformer. The low-pass filters may also be configured in a "secondary side control" configuration.

[0096] *Voltage sensor unit SEv* A U-phase voltage sensor SEvu is provided across the primary winding Wuf of the U-phase transformer to detect the internal U-phase voltage Viu. A V-phase voltage sensor SEvv is provided across the primary winding Wvf of the V-phase transformer to detect the internal V-phase voltage Viv. A W-phase voltage sensor SEvw is provided across the primary winding Wwf of the W-phase transformer to detect the internal W-phase voltage Viw. The U-phase voltage sensor SEvu, V-phase voltage sensor SEvv, and W-phase voltage sensor SEvw together constitute a voltage sensor unit SEv that detects the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi. Here, the voltage sensor unit SEv is provided to correspond to "primary side control." In the case of "secondary side control," the voltage sensor unit SEv is provided on the output side of the capacitor of the low-pass filter on the secondary side of the three-phase transformer unit to detect the external zero-phase-sequence-containing unbalanced three-phase voltage Vubo.

[0097] <Action and effect> According to this first zero-phase output configuration, an internal zero-phase-containing unbalanced three-phase voltage Vubi is generated in the main circuit 2A. However, the DC power supply DC, the three inverter sections INVu to INVw of the three-phase inverter device INV, and the three winding sections Tu to Tw of the three-phase transformer device corresponding to the three phases are each composed of three DC power supply sections DCu to DCw of the DC power supply DC, three single-phase inverters of the three-phase inverter unit, and three single-phase transformers of the three-phase transformer unit, which are independent of one another. Therefore, the current of the zero-phase component of the internal zero-phase-containing unbalanced three-phase voltage Vubi flows through the DC power supply sections DCu to DCw, the single-phase inverters, and the primary windings Wuf to Wwf of the single-phase transformers corresponding to each phase, respectively, in accordance with the phase voltages Viu to Viw of the three phases, which are unbalanced with one another. Furthermore, since the secondary windings Wus-Wws of the single-phase transformers corresponding to the three phases are Y-connected, the external zero-phase-containing unbalanced three-phase voltage Vubo, which is obtained by converting the internal zero-phase-containing unbalanced three-phase voltage Vubi in accordance with the turns ratio, is output by the secondary windings Wus-Wws and secondary winding neutral point Ns of the Y-connected single-phase transformers corresponding to the three phases. As a result, it is possible to suitably configure a combination of a DC power supply DC, a three-phase inverter device INV, and a three-phase transformer device T that is capable of outputting the zero-phase component of the external zero-phase-containing unbalanced three-phase voltage Vubo.

[0098] <<Main circuit 2A including second zero-phase output configuration>> Fig. 3 is a circuit diagram showing details of the main circuit 2A including the second zero-phase output configuration in Fig. 1. Hereinafter, the contents of the main circuit 2A including the second zero-phase output configuration will be described with reference to Fig. 3.

[0099] <DC power supply DC> The direct current power supply DC of the second zero-phase output configuration is the same as the direct current power supply DC of the first zero-phase output configuration, and therefore a description thereof will be omitted.

[0100] <Three-phase inverter INV> The three-phase inverter device INV of the second zero-phase output configuration is the same as the three-phase inverter device INV of the first zero-phase output configuration, and therefore a description thereof will be omitted.

[0101] <Three-phase transformer T> The three-phase transformer device T is configured with a three-phase five-legged core transformer. Three-phase five-legged core transformers are well known, so only a brief description will be given. The three-phase five-legged core transformer includes a three-phase five-legged core (not shown) having a U-leg, a V-leg, a W-leg, and a pair of magnetic leakage legs provided on both sides of the U-leg, the V-leg, and the W-leg, a U-phase winding section Tu provided on the U-phase leg, a V-phase winding section Tv provided on the V-phase leg, and a W-phase winding section Tw provided on the W-phase leg.

[0102] The primary winding Wuf of the U-phase winding section Tu is connected to the output terminal of the U-phase inverter via a low-pass filter Flu. The primary winding Wvf of the V-phase winding section Tv is connected to the output terminal of the V-phase inverter via a low-pass filter Flv. The primary winding Wwf of the W-phase winding section Tw is connected to the output terminal of the W-phase inverter via a low-pass filter Flw.

[0103] The secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, and the secondary winding Wws of the W-phase winding section Tw are star-connected at the secondary winding neutral point Ns.

[0104] In a three-phase five-legged core transformer, the internal U-phase voltage Viu, internal V-phase voltage Viv, and internal W-phase voltage Viw of the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi from the three-phase inverter unit are input to the primary winding Wuf of the U-phase winding section Tu, the primary winding Wvf of the V-phase winding section Tv, and the primary winding Wwf of the W-phase winding section Tw, respectively. Furthermore, the internal U-phase voltage Viu, internal V-phase voltage Viv, and internal W-phase voltage Viw are converted according to a predetermined turns ratio in the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, and the secondary winding Wws of the W-phase winding section Tw to generate an external zero-phase-sequence-containing unbalanced three-phase voltage Vubo including an external U-phase voltage Vou, an external V-phase voltage Vov, and an external W-phase voltage Vow, respectively. This external zero-phase-sequence-containing unbalanced three-phase voltage Vubo is output by the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, the secondary winding Wws of the W-phase winding section Tw, and the secondary winding neutral point Ns, which are all connected in a Y-connection of the three-phase five-leg core transformer. Reference symbols U, V, W, and n denote the U-phase, V-phase, W-phase, and zero-phase output terminals on the secondary side of the three-phase five-leg core transformer, respectively.

[0105] <Elements other than the second zero-phase output configuration> *Low pass filter* Here, the low-pass filters are configured for "primary side control." A U-phase low-pass filter Flu is arranged between the output terminal of the U-phase inverter and the primary winding Wuf of the U-phase winding section Tu. A V-phase low-pass filter Flv is arranged between the output terminal of the V-phase inverter and the primary winding Wvf of the V-phase winding section Tv. A W-phase low-pass filter Flw is arranged between the output terminal of the W-phase inverter and the primary winding Wwf of the W-phase winding section Tw. The low-pass filters may also be configured for "secondary side control."

[0106] *Voltage sensor unit SEv* A U-phase voltage sensor SEvu is provided across both ends of the primary winding Wuf of the U-phase winding section Tu to detect the internal U-phase voltage Viu. A V-phase voltage sensor SEvv is provided across both ends of the primary winding Wvf of the V-phase winding section Tv to detect the internal V-phase voltage Viv. A W-phase voltage sensor SEvw is provided across both ends of the primary winding Wwf of the W-phase winding section Tw to detect the internal W-phase voltage Viw. The U-phase voltage sensor SEvu, V-phase voltage sensor SEvv, and W-phase voltage sensor SEvw constitute a voltage sensor unit SEv that detects the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi. Here, the voltage sensor unit SEv is provided to correspond to "primary side control." In the case of "secondary side control," the voltage sensor unit SEv is provided on the output side of the capacitor of the low-pass filter on the secondary side of the three-phase five-legged transformer to detect the external zero-phase-sequence-containing unbalanced three-phase voltage Vubo.

[0107] <Action and effect> According to this second zero-phase output configuration, an internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi is generated in the main circuit 2A. However, the DC power supply DC, the three inverter sections INVu to INVw of the three-phase inverter device INV, and the three winding sections Tu to Tw of the three-phase five-leg core transformer corresponding to the three phases are respectively configured by three DC power supply sections DCu to DCw of the DC power supply DC, three single-phase inverters of the three-phase inverter unit, and three winding sections Tu to Tw of the three-phase five-leg core transformer that are independent of one another. Therefore, the current of the zero-phase component of the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi flows through the DC power supply sections DCu to DCw, the single-phase inverter, and the primary windings Wuf to Wwf of the winding sections Tu to Tw of the three-phase five-leg core transformer corresponding to each phase, respectively, in accordance with the phase voltages Viu to Viw of the three phases that are unbalanced with one another. The secondary windings Wus-Wws of the winding sections Tu-Tw of the three-phase five-leg core transformer corresponding to the three phases are Y-connected, and the external zero-phase-containing unbalanced three-phase voltage Vubo, which is obtained by converting the internal zero-phase-containing unbalanced three-phase voltage Vubi according to the turns ratio, is output by the secondary windings Wus-Wws and secondary winding neutral point Ns of the winding sections Tu-Tw of the three-phase five-leg core transformer corresponding to the Y-connected three phases. In this case, the zero-phase magnetic flux passes through a pair of magnetic leakage legs. As a result, a suitable combination of a DC power supply DC, a three-phase inverter device INV, and a three-phase transformer device T can be constructed that can output the zero-phase component of the external zero-phase-containing unbalanced three-phase voltage Vubo.

[0108] <Main circuit 2A including the third zero-phase output configuration> Fig. 4 is a circuit diagram showing details of the main circuit 2A including the third zero-phase output configuration in Fig. 1. Hereinafter, the contents of the main circuit 2A including the third zero-phase output configuration will be described with reference to Fig. 4.

[0109] <DC power supply DC> The DC power supply DC includes a positive DC power supply unit DCp and a negative DC power supply unit DCn, which are connected in series with each other at a power supply neutral point Ndc and each output a predetermined DC voltage. The positive DC power supply unit DCp and the negative DC power supply unit DCn are not particularly limited as long as they are DC voltage sources capable of outputting the predetermined DC voltage. Examples of the positive DC power supply unit DCp and the negative DC power supply unit DCn include a capacitor, a DC / DC converter, a rectifier, and a rechargeable battery. Here, the positive DC power supply unit DCp and the negative DC power supply unit DCn are each composed of a capacitor. In this case, a DC power supply device (not shown) is provided in front of this pair of capacitors to charge the pair of capacitors.

[0110] <Three-phase inverter INV> The three-phase inverter device INV is configured as a three-phase, four-wire inverter. The three-phase, four-wire inverter may be a three-phase, four-wire inverter, and the configuration of the inverter unit (switching unit) is not particularly limited. The three-phase, four-wire inverter includes, for example, a U-phase inverter unit INVu consisting of a half-bridge, a V-phase inverter unit INVv consisting of a half-bridge, and a W-phase inverter unit INVw consisting of a half-bridge. Half-bridge type three-phase, four-wire inverters are well known, so they will be briefly described below.

[0111] The U-phase inverter unit INVu has two switching elements Q1u and Q2u connected to half-ridges. In the U-phase inverter unit INVu, the positive input terminal is connected to the positive terminal of the positive DC power supply unit DCp, and the negative input terminal is connected to the negative terminal of the negative DC power supply unit DCn. A U-phase positive-phase pulse modulated signal Spup and a U-phase negative-phase pulse modulated signal Spuo, which constitute the U-phase pulse modulated signal Spu from the pulse modulated signal generation circuit 4, are input to the switching element Q1u and the switching element Q2u, respectively. The U-phase inverter unit INVu alternately turns on and off a switching element Q1u in accordance with a U-phase positive-phase pulse modulation signal Spup and a switching element Q2u in accordance with a U-phase negative-phase pulse modulation signal Spuo, thereby generating an internal U-phase voltage Viu having a phase, frequency, and amplitude corresponding to a phase command value Cphu and an amplitude command value Camu of the U-phase of a predetermined zero-phase-containing unbalanced three-phase voltage from a predetermined DC voltage supplied from the positive DC power supply unit DCp and the negative DC power supply unit DCn, and outputs the internal U-phase voltage Viu from an output terminal.

[0112] The V-phase inverter section INVv has two switching elements Q1v and Q2v connected to half-ridges. In the V-phase inverter section INVv, the positive input terminal is connected to the positive terminal of the positive DC power supply section DCp, and the negative input terminal is connected to the negative terminal of the negative DC power supply section DCn. A V-phase positive-phase pulse modulated signal Spvp and a V-phase negative-phase pulse modulated signal Spvo that constitute the V-phase pulse modulated signal Spv from the pulse modulated signal generation circuit 4 are input to switching element Q1v and switching element Q2v, respectively. The V-phase inverter unit INVv alternately turns on and off a switching element Q1v in accordance with the V-phase positive-phase pulse modulation signal Spvp and a switching element Q2v in accordance with the V-phase negative-phase pulse modulation signal Spvo, thereby generating an internal V-phase voltage Viv having a phase, frequency, and amplitude corresponding to a V-phase phase command value Cphv and an amplitude command value Camv of a predetermined zero-phase-containing unbalanced three-phase voltage from a predetermined DC voltage supplied from the positive DC power supply unit DCp and the negative DC power supply unit DCn, and outputs the internal V-phase voltage Viv from an output terminal.

[0113] The W-phase inverter section INVw has two switching elements Q1w and Q2w connected to half-ridges. In the W-phase inverter section INVw, the positive input terminal is connected to the positive terminal of the positive DC power supply section DCp, and the negative input terminal is connected to the negative terminal of the negative DC power supply section DCn. A W-phase positive-phase pulse modulated signal Spwp and a W-phase negative-phase pulse modulated signal Spwo, which constitute the W-phase pulse modulated signal Spw from the pulse modulated signal generation circuit 4, are input to switching element Q1w and switching element Q2w, respectively. The W-phase inverter unit INVw alternately turns on and off a switching element Q1w in accordance with the W-phase positive-phase pulse modulation signal Spwp and a switching element Q2w in accordance with the W-phase negative-phase pulse modulation signal Spwo, thereby generating an internal W-phase voltage Viw from a predetermined DC voltage from the positive DC power supply unit DCp and the negative DC power supply unit DCn, the internal W-phase voltage Viw having a phase, frequency, and amplitude corresponding to a W-phase phase command value Cphw and an amplitude command value Camw of a predetermined zero-phase-containing unbalanced three-phase voltage, and outputs the internal W-phase voltage Viw from an output terminal.

[0114] In this way, the U-phase inverter unit INVu, the V-phase inverter unit INVv, and the W-phase inverter unit INVw output the internal zero-phase-containing unbalanced three-phase voltage Vubi, which includes the internal U-phase voltage Viu, the internal V-phase voltage Viv, and the internal W-phase voltage Viw as the U-phase voltage, the V-phase voltage, and the W-phase voltage, respectively.

[0115] <Three-phase transformer T> The three-phase transformer T of the third zero-phase output configuration is similar to the three-phase transformer T of the first zero-phase output configuration, so only the differences between the three-phase transformer T of the third zero-phase output configuration and the three-phase transformer T of the first zero-phase output configuration will be explained.

[0116] In the third zero-phase output configuration, the primary winding Wuf of the U-phase transformer is connected to the output terminal of the U-phase inverter unit INVu via a low-pass filter Flu. The primary winding Wvf of the V-phase transformer is connected to the output terminal of the V-phase inverter unit INVv via a low-pass filter Flv. The primary winding Wwf of the W-phase transformer is connected to the output terminal of the W-phase inverter unit INVw via a low-pass filter Flw.

[0117] The primary winding Wuf of the U-phase transformer, the primary winding Wvf of the V-phase transformer, and the primary winding Wwf of the W-phase transformer are Y-connected at the primary winding neutral point Nf. The primary winding neutral point Nf is connected to the power supply neutral point Ndc, for example, by a neutral wire Wn. Note that the primary winding neutral point Nf and the power supply neutral point Ndc may be grounded, thereby connecting the primary winding neutral point Nf to the power supply neutral point Ndc. As a result, the U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw of the three-phase four-wire inverter are Y-connected at the power supply neutral point Ndc via a common positive DC power supply section DCp and negative DC power supply section DCn, and the Y-connected U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw and positive DC power supply section DCp and negative DC power supply section DCn are Y / Y-connected with the U-phase transformer, V-phase transformer, and W-phase transformer of the Y-connected three-phase transformer unit.

[0118] The secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, and the secondary winding Wws of the W-phase transformer are star-connected at the secondary winding neutral point Ns.

[0119] In the three-phase transformer unit, the internal U-phase voltage Viu, internal V-phase voltage Viv, and internal W-phase voltage Viw of the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi from the three-phase four-wire inverter are input to the primary winding Wuf of the U-phase transformer, the primary winding Wvf of the V-phase transformer, and the primary winding Wwf of the W-phase transformer, respectively. The internal U-phase voltage Viu, internal V-phase voltage Viv, and internal W-phase voltage Viw are converted in the secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, and the secondary winding Wws of the W-phase transformer according to a predetermined turns ratio to generate an external zero-phase-sequence-containing unbalanced three-phase voltage Vubo including an external U-phase voltage Vou, an external V-phase voltage Vov, and an external W-phase voltage Vow. This external zero-phase-sequence-containing unbalanced three-phase voltage Vubo is then output by the secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, the secondary winding Wws of the W-phase transformer, and the secondary winding neutral point Ns, which are all connected in a Y-connection in the three-phase transformer unit.

[0120] <Elements other than the third zero-phase output configuration> *Low pass filter* Here, the low-pass filters are configured in a "primary side control" configuration. A U-phase low-pass filter Flu is arranged between the primary winding Wuf of the U-phase transformer and the output terminal of the U-phase inverter unit INVu. A V-phase low-pass filter Flv is arranged between the primary winding Wvf of the V-phase transformer and the output terminal of the V-phase inverter unit INVv. A W-phase low-pass filter Flw is arranged between the primary winding Wwf of the W-phase transformer and the output terminal of the W-phase inverter unit INVw. The low-pass filters may also be configured in a "secondary side control" configuration.

[0121] *Voltage sensor unit SEv* The voltage sensor unit SEv of the main circuit 2A including the third zero-phase output configuration is the same as the voltage sensor unit SEv of the main circuit 2A including the first zero-phase output configuration, and therefore a description thereof will be omitted.

[0122] <Action and effect> According to this third zero-phase output configuration, the Y-connected U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw as well as the positive DC power supply section DCp and negative DC power supply section DCn are Y / Y-connected with the U-phase transformer, V-phase transformer, and W-phase transformer of the Y-connected three-phase transformer unit. Therefore, the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi output from the U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw of the three-phase four-wire inverter is applied to the primary windings Wuf to Wwf of the U-phase transformer, V-phase transformer, and W-phase transformer of the three-phase transformer unit, and a current of the zero-phase component of the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi flows in a current path between the primary winding neutral point Nf and the power supply neutral point Ndc. Furthermore, because the secondary windings Wus-Wws of the U-phase transformer, V-phase transformer, and W-phase transformer of the three-phase transformer unit are Y-connected, the external zero-phase-containing unbalanced three-phase voltage Vubo, which is obtained by converting the internal zero-phase-containing unbalanced three-phase voltage Vubi in accordance with the turns ratio, is output by the secondary windings Wus-Wws and secondary winding neutral point Ns of the Y-connected U-phase transformer, V-phase transformer, and W-phase transformer. As a result, it is possible to suitably configure a combination of a DC power supply DC, a three-phase inverter device INV, and a three-phase transformer device T that is capable of outputting the zero-phase component of the external zero-phase-containing unbalanced three-phase voltage Vubo.

[0123] <Main circuit 2A including 4th zero-phase output configuration> Fig. 5 is a circuit diagram showing details of the main circuit 2A including the fourth zero-phase output configuration in Fig. 1. Hereinafter, the contents of the main circuit 2A including the fourth zero-phase output configuration will be described with reference to Fig. 5.

[0124] <DC power supply DC> The direct current power supply DC of the fourth zero-phase output configuration is the same as the direct current power supply DC of the third zero-phase output configuration, and therefore a description thereof will be omitted.

[0125] <Three-phase inverter INV> The three-phase inverter device INV of the fourth zero-phase output configuration is the same as the three-phase inverter device INV of the third zero-phase output configuration, and therefore a description thereof will be omitted.

[0126] <Three-phase transformer T> Since the three-phase transformer T of the fourth zero-phase output configuration is similar to the three-phase transformer T of the second zero-phase output configuration, only the differences between the three-phase transformer T of the fourth zero-phase output configuration and the three-phase transformer T of the second zero-phase output configuration will be explained.

[0127] In the fourth zero-phase output configuration, the primary winding Wuf of the U-phase winding section Tu is connected to the output terminal of the U-phase inverter section INVu via a low-pass filter Flu. The primary winding Wvf of the V-phase winding section Tv is connected to the output terminal of the V-phase inverter section INVv via a low-pass filter Flv. The primary winding Wwf of the W-phase winding section Tw is connected to the output terminal of the W-phase inverter section INVw via a low-pass filter Flw.

[0128] The primary winding Wuf of the U-phase winding section Tu, the primary winding Wvf of the V-phase winding section Tv, and the primary winding Wwf of the W-phase winding section Tw of the three-phase five-legged core transformer are Y-connected at the primary winding neutral point Nf. The primary winding neutral point Nf is connected to the power supply neutral point Ndc, for example, by a neutral wire Wn. Note that the primary winding neutral point Nf and the power supply neutral point Ndc may be grounded, thereby connecting the primary winding neutral point Nf to the power supply neutral point Ndc. As a result, the U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw of the three-phase four-wire inverter are Y-connected at the power supply neutral point Ndc via a common positive DC power supply section DCp and negative DC power supply section DCn, and the Y-connected U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw and positive DC power supply section DCp and negative DC power supply section DCn are Y / Y-connected with the U-phase winding section Tu, V-phase winding section Tv, and W-phase winding section Tw of the Y-connected three-phase five-legged core transformer.

[0129] The secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, and the secondary winding Wws of the W-phase winding section Tw are star-connected at the secondary winding neutral point Ns.

[0130] In a three-phase five-legged core transformer, the internal U-phase voltage Viu, internal V-phase voltage Viv, and internal W-phase voltage Viw of the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi from the three-phase four-wire inverter are input to the primary winding Wuf of the U-phase winding section Tu, the primary winding Wvf of the V-phase winding section Tv, and the primary winding Wwf of the W-phase winding section Tw, respectively. Furthermore, the internal U-phase voltage Viu, the internal V-phase voltage Viv, and the internal W-phase voltage Viw are converted according to a predetermined turns ratio in the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, and the secondary winding Wws of the W-phase winding section Tw to generate an external zero-phase-sequence-containing unbalanced three-phase voltage Vubo including an external U-phase voltage Vou, an external V-phase voltage Vov, and an external W-phase voltage Vow, respectively. This external zero-phase-sequence-containing unbalanced three-phase voltage Vubo is output by the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, the secondary winding Wws of the W-phase winding section Tw, and the secondary winding neutral point Ns, which are all connected in a Y-connection of a three-phase five-legged core transformer.

[0131] <Elements other than the 4th zero-phase output configuration> *Low pass filter* Here, the low-pass filters are configured in a "primary side control" configuration. A U-phase low-pass filter Flu is arranged between the primary winding Wuf of the U-phase winding section Tu and the output terminal of the U-phase inverter section INVu. A V-phase low-pass filter Flv is arranged between the primary winding Wvf of the V-phase winding section Tv transformer and the output terminal of the V-phase inverter section INVv. A W-phase low-pass filter Flw is arranged between the primary winding Wwf of the W-phase winding section Tw and the output terminal of the W-phase inverter section INVw. The low-pass filters may also be configured in a "secondary side control" configuration.

[0132] *Voltage sensor unit SEv* The voltage sensor unit SEv of the main circuit 2A including the fourth zero-phase output configuration is the same as the voltage sensor unit SEv of the main circuit 2A including the second zero-phase output configuration, and therefore a description thereof will be omitted.

[0133] <Action and effect> According to this fourth zero-phase output configuration, the Y-connected U-phase inverter unit INVu, V-phase inverter unit INVv, and W-phase inverter unit INVw, as well as the positive DC power supply unit DCp and negative DC power supply unit DCn, are Y / Y connected to the Y-connected U-phase winding unit Tu, V-phase winding unit Tv, and W-phase winding unit Tw of the three-phase five-leg core transformer. Therefore, the internal zero-phase-containing unbalanced three-phase voltage Vubi output from the U-phase inverter unit INVu, V-phase inverter unit INVv, and W-phase inverter unit INVw of the three-phase four-wire inverter is applied to the primary windings Wuf to Wwf of the U-phase winding unit Tu, V-phase winding unit Tv, and W-phase winding unit Tw of the three-phase five-leg core transformer, and a current of the zero-phase component of the internal zero-phase-containing unbalanced three-phase voltage Vubi flows in a current path between the primary winding neutral point Nf and the power supply neutral point Ndc. Furthermore, the secondary windings Wus-Wws of the U-phase winding section Tu, V-phase winding section Tv, and W-phase winding section Tw are Y-connected, so that the internal zero-phase-containing unbalanced three-phase voltage Vubi is converted in accordance with the turns ratio to generate an external zero-phase-containing unbalanced three-phase voltage Vubo, which is output by the Y-connected secondary windings Wus-Wws of the U-phase winding section Tu, V-phase winding section Tv, and W-phase winding section Tw and the secondary winding neutral point Ns. In this case, the zero-phase magnetic flux passes through a pair of magnetic leakage legs. As a result, a suitable combination of a DC power supply DC, a three-phase inverter device INV, and a three-phase transformer device T can be constructed that can output the zero-phase component of the external zero-phase-containing unbalanced three-phase voltage Vubo.

[0134] {Control circuit 1A} Fig. 6 is a circuit diagram showing an example of the configuration of the control circuit 1A of Fig. 1. Referring to Fig. 6, the control circuit 1A is configured to perform feedback control of the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi. Note that the control circuit 1A may also be configured to perform feedforward control.

[0135] Specifically, the control circuit 1A includes a voltage command generating section 3, a voltage feedback control section 5, and a pulse modulation signal generating circuit 4. These elements will be described in detail below in order.

[0136] <Voltage command generation unit 3> The voltage command generating unit 3 includes a phase command value generating unit 31 , a three-phase sine wave generating unit 32 , and a voltage command amplitude determining unit 33 .

[0137] The phase command value generating unit 31 receives a U-phase phase command value Cphu, a V-phase phase command value Cphv, and a W-phase phase command value Cphw of a predetermined zero-phase-containing unbalanced three-phase voltage from the upper controller 10. The phase command value generating unit 31 also receives phase information IFrphu of a U-phase reference internal sine wave, phase information IFrphv of a V-phase reference internal sine wave, and phase information IFrphw of a W-phase reference internal sine wave generated by a reference internal three-phase sine wave generating unit (not shown) of the unbalanced three-phase power supply device 100.

[0138] The reference internal three-phase sine wave generator generates a reference internal sine wave for each phase based on the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi detected by the voltage sensor unit SEv, and extracts the phase of the reference internal sine wave for each phase. These processes can be performed by a well-known method using a PLL, so a description thereof will be omitted.

[0139] The phase command value generator 31 adds the U-phase phase command value Cphu, the V-phase phase command value Cphv, and the W-phase phase command value Cphw to the phase information IFrphu of the U-phase reference internal sine wave, the phase information IFrphv of the V-phase reference internal sine wave, and the phase information IFrphw of the W-phase reference internal sine wave, respectively, using the U-phase adder 311, the V-phase adder 312, and the W-phase adder 313, and outputs the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value obtained by this addition. At this time, the phase command value generator 31 outputs the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value at a predetermined timing, that is, when a predetermined time has elapsed from a predetermined reference time. The higher-level controller 10 will be described later.

[0140] The three-phase sine wave generator 32 includes a U-phase sine table 321, a V-phase sine table 322, and a W-phase sine table 323. The sine table is a table (graph) showing a relationship (function) in which the frequency of a sine wave is proportional to time in a two-axis Cartesian coordinate system, where one axis represents the elapsed time from the predetermined reference time and the other axis represents the frequency of the sine wave. When the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value are input from the phase command value generator 31, the three-phase sine wave generator 32 identifies the input timing of each, i.e., the elapsed time from the predetermined reference time until the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value are input, and compares the identified input timing of the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value with the U-phase sine table 321, the V-phase sine table 322, and the W-phase sine table 323, respectively. The three-phase sine wave generator 32 determines the frequencies corresponding to the input timing of the U-phase phase command value, the input timing of the V-phase phase command value, and the input timing of the W-phase phase command value as the frequencies of the U-phase sine wave, the V-phase sine wave, and the W-phase sine wave, respectively, in the U-phase sine table 321, the V-phase sine table 322, and the W-phase sine table 323. The three-phase sine wave generator 32 also determines the phases indicated by the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value, respectively, as the phases of the U-phase sine wave, the V-phase sine wave, and the W-phase sine wave. In this way, the three-phase sine wave generator 32 generates U-phase sine waves, V-phase sine waves, and W-phase sine waves having frequencies, phases, and reference amplitudes corresponding to the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value, respectively.

[0141] The voltage command amplitude determiner 33 receives a U-phase amplitude command value Camu, a V-phase amplitude command value Camv, and a W-phase amplitude command value Camw of a predetermined zero-phase-containing unbalanced three-phase voltage from the higher-level controller 10. The voltage command amplitude determiner 33 determines the amplitudes of the U-phase sine wave, the V-phase sine wave, and the W-phase sine wave by multiplying the amplitude values of the U-phase sine wave, the V-phase sine wave, and the W-phase sine wave generated by the three-phase sine wave generator 32 by the U-phase, V-phase, and W-phase amplitude command values of the predetermined zero-phase-containing unbalanced three-phase voltage, respectively, using a U-phase multiplier 331, a V-phase multiplier 332, and a W-phase multiplier 333, and thereby generates a U-phase voltage command Cvu, a V-phase voltage command Cvv, and a W-phase voltage command Cvw.

[0142] <Voltage feedback control unit 5> The voltage feedback control unit 5 includes a voltage error generating unit 51 and a voltage compensating unit 52.

[0143] The internal U-phase voltage Viu, internal V-phase voltage Viv, and internal W-phase voltage Viw of the internal zero-phase-containing unbalanced three-phase voltage Vubi detected by the voltage sensor unit SEv are input to the voltage error generator 51. Using a U-phase subtractor 511, a V-phase subtractor 512, and a W-phase subtractor 513, the voltage error generator 51 generates a U-phase voltage error, a V-phase voltage error, and a W-phase voltage error, which are errors between the internal U-phase voltage Viu, the internal V-phase voltage Viv, and the internal W-phase voltage Viw of the internal zero-phase-containing unbalanced three-phase voltage Vubi and the U-phase voltage command Cvu, the V-phase voltage command Cvv, and the W-phase voltage command Cvw generated by the voltage command amplitude determiner 33. In the case of “secondary-side control,” the external U-phase voltage Vou, the external V-phase voltage Vov, and the external W-phase voltage Vow of the external zero-sequence-containing unbalanced three-phase voltage Vubo detected by the voltage sensor unit SEv are input to the voltage error generating unit 51, and the voltage error generating unit 51 uses a U-phase subtractor 511, a V-phase subtractor 512, and a W-phase subtractor 513 to generate a U-phase voltage error, a V-phase voltage error, and a W-phase voltage error, which are errors between the external U-phase voltage Vou, the external V-phase voltage Vov, and the external W-phase voltage Vow of the external zero-sequence-containing unbalanced three-phase voltage Vubo and the U-phase voltage command Cvu, the V-phase voltage command Cvv, and the W-phase voltage command Cvw generated by the voltage command amplitude determining unit 33.

[0144] The voltage compensator 52 generates a U-phase feedback voltage manipulated variable, a V-phase feedback voltage manipulated variable, and a W-phase feedback voltage manipulated variable by applying compensation to the U-phase voltage error, V-phase voltage error, and W-phase voltage error generated by the voltage error generator 51 using a U-phase compensator 521, a V-phase compensator 531, and a W-phase compensator 541. Examples of compensation performed by the U-phase compensator 521, the V-phase compensator 531, and the W-phase compensator 541 include P compensation, PI compensation, and PID compensation. Furthermore, the voltage compensator 52 generates appropriate U-phase feedforward voltage manipulated variables, V-phase feedforward voltage manipulated variables, and W-phase feedforward voltage manipulated variables corresponding to the U-phase voltage command Cvu, V-phase voltage command Cvv, and W-phase voltage command Cvw, respectively, using a U-phase feedforward controller 522, a V-phase feedforward controller 532, and a W-phase feedforward controller 542. Then, the voltage compensator 52 uses a U-phase adder 523, a V-phase adder 533, and a W-phase adder 543 to add the U-phase feedforward voltage control variable, the V-phase feedforward voltage control variable, and the W-phase feedforward voltage control variable to the U-phase feedback voltage control variable, the V-phase feedback voltage control variable, and the W-phase feedback voltage control variable, respectively, to generate a U-phase voltage control variable Ovu, a V-phase voltage control variable Ovv, and a W-phase voltage control variable Ovw. Note that the U-phase feedforward control unit 522, the V-phase feedforward control unit 532, and the W-phase feedforward control unit 542 may be omitted. In this case, the U-phase feedback control variable, the V-phase feedback control variable, and the W-phase feedback control variable become the U-phase voltage control variable Ovu, the V-phase voltage control variable Ovv, and the W-phase voltage control variable Ovw, respectively.

[0145] <Pulse modulation signal generation circuit 4> The pulse modulated signal generating circuit 4 includes a U-phase comparator 41, a U-phase inverting element , a V-phase comparator 43, a V-phase inverting element , a W-phase comparator 45, and a W-phase inverting element .

[0146] U-phase comparator 41 receives U-phase voltage control variable Ovu generated by voltage compensation unit 52 at its non-inverting input terminal and triangular wave carrier signal Vcu at its inverting input terminal. U-phase comparator 41 compares U-phase voltage control variable Ovu with triangular wave carrier signal Vcu to generate U-phase positive-phase pulse modulated signal Spup, which is a PWM signal corresponding to U-phase voltage control variable Ovu. U-phase inverting element 42 inverts U-phase positive-phase pulse modulated signal Spup to generate U-phase negative-phase pulse modulated signal Spuo. U-phase positive-phase pulse modulated signal Spup and U-phase negative-phase pulse modulated signal Spuo constitute U-phase pulse modulated signal Spu.

[0147] The V-phase comparator 43 receives the V-phase voltage control variable Ovv generated by the voltage compensation unit 52 at its non-inverting input terminal and the triangular wave carrier signal Vcv at its inverting input terminal. The V-phase comparator 43 compares the V-phase voltage control variable Ovv with the triangular wave carrier signal Vcv to generate a V-phase positive-phase pulse modulated signal Spvp, which is a PWM signal corresponding to the V-phase voltage control variable Ovv. The V-phase inverting element 44 inverts the V-phase positive-phase pulse modulated signal Spvp to generate a V-phase negative-phase pulse modulated signal Spvo. The V-phase positive-phase pulse modulated signal Spvp and the V-phase negative-phase pulse modulated signal Spvo constitute the V-phase pulse modulated signal Spv.

[0148] The W-phase comparator 45 receives the W-phase voltage control variable Ovw generated by the voltage compensation unit 52 at its non-inverting input terminal and receives the triangular wave carrier signal Vcw at its inverting input terminal. The W-phase comparator 45 compares the W-phase voltage control variable Ovw with the triangular wave carrier signal vcw to generate a W-phase positive-phase pulse modulated signal Spwp, which is a PWM signal corresponding to the W-phase voltage control variable Ovw. The W-phase inverting element 46 inverts the W-phase positive-phase pulse modulated signal Spwp to generate a W-phase negative-phase pulse modulated signal Spwo. The W-phase positive-phase pulse modulated signal Spwp and the W-phase negative-phase pulse modulated signal Spwo constitute the W-phase pulse modulated signal Spw.

[0149] <Configuration of voltage command generating unit 3 and voltage feedback control unit 5> The voltage command generating unit 3 and the voltage feedback control unit 5, excluding the three-phase sine wave generating unit 32, can be configured by an electronic circuit using, for example, an operational amplifier.

[0150] Furthermore, the voltage command generation unit 3 and the voltage feedback control unit 5 can be configured by software. In this case, for example, a computing unit having a processor and a memory is used, and a predetermined program for executing the functions of the voltage command generation unit 3 and the voltage feedback control unit 5 is stored in the memory of the computing unit. The predetermined program is read and executed by the processor, thereby realizing the voltage command generation unit 3 and the voltage feedback control unit 5 as functional blocks. In this case, the computing unit operates as the voltage command generation unit 3 and the voltage feedback control unit 5. This computing unit can be configured by, for example, a computer, a personal computer, a microcontroller, an MPU, an FPGA (Field Programmable Gate Array), a PLC (Programmable Logic Controller), or the like.

[0151] It should be noted that the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this disclosure, a "circuit" or "unit" is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where hardware is a processor, which is considered a type of circuit, the "circuit" or "unit" is a combination of hardware and software, and software is used to configure the hardware and / or processor.

[0152] <Host controller 10> The upper controller 10 is not particularly limited as long as it can output a U-phase phase command value Cphu, a V-phase phase command value Cphv, and a W-phase phase command value Cphw of a predetermined zero-phase-containing unbalanced three-phase voltage, as well as a U-phase amplitude command value Camu, a V-phase amplitude command value Camv, and a W-phase amplitude command value Camw. The upper controller 10 is configured, for example, with a computer, a personal computer, a microcontroller, an MPU, an FPGA, a PLC, or the like. Communication between the upper controller 10 and the voltage command generating unit 3 is performed, for example, via a wired or wireless connection, a data communication network, or the like. The upper controller 10 may be located either outside or inside the unbalanced three-phase power supply device 100.

[0153] <Operation> The operation of the unbalanced three-phase power supply device 100 configured as above will be described with reference to Figures 1 to 6. In the following, a case where the control circuit 1A includes a voltage feedback control unit 5 will be described.

[0154] 1 and 6, the voltage command generation unit 3 receives a U-phase phase command value Cphu, a V-phase phase command value Cphv, and a W-phase phase command value Cphw, as well as a U-phase amplitude command value Camu, a V-phase amplitude command value Camv, and a W-phase amplitude command value Camw of a predetermined zero-phase-containing unbalanced three-phase voltage from the upper controller 10. The voltage command generation unit 3 generates a U-phase voltage command Cvu, a V-phase voltage command Cvv, and a W-phase voltage command Cvw having phases, frequencies, and amplitudes corresponding to the received U-phase phase command value Cphu, a V-phase phase command value Cphv, and a W-phase phase command value Cphw, as well as the U-phase amplitude command value Camu, a V-phase amplitude command value Camv, and a W-phase amplitude command value Camw, respectively.

[0155] The voltage feedback control unit 5 generates a U-phase voltage control variable Ovu, a V-phase voltage control variable Ovv, and a W-phase voltage control variable Ovw based on errors of the internal U-phase voltage Viu, the internal V-phase voltage Viv, and the internal W-phase voltage Viw of the internal zero-sequence-containing unbalanced three-phase voltage Vubi relative to the U-phase voltage command Cvu, the V-phase voltage command Cvv, and the W-phase voltage command Cvw from the voltage command generation unit 3. In the case of “secondary side control,” the voltage feedback control unit 5 generates the U-phase voltage control variable Ovu, the V-phase voltage control variable Ovv, and the W-phase voltage control variable Ovw based on errors of the external U-phase voltage Vou, the external V-phase voltage Vov, and the external W-phase voltage Vow of the external zero-sequence-containing unbalanced three-phase voltage Vubo relative to the U-phase voltage command Cvu, the V-phase voltage command Cvv, and the W-phase voltage command Cvw from the voltage command generation unit 3.

[0156] The pulse modulation signal generation circuit 4 outputs a U-phase pulse modulation signal Spu, a V-phase pulse modulation signal Spv, and a W-phase pulse modulation signal Spw, which correspond to the U-phase voltage control amount Ovu, the V-phase voltage control amount Ovv, and the W-phase voltage control amount Ovw, which are generated by the voltage feedback control unit 5.

[0157] 1 and 2 to 5, the U-phase inverter unit INVu, V-phase inverter unit INVv, and W-phase inverter unit INVw of the three-phase inverter device INV generate, from a predetermined DC voltage from the DC power supply DC, an internal U-phase voltage Viu, an internal V-phase voltage Viv, and an internal W-phase voltage Viw having phases, frequencies, and amplitudes corresponding to the U-phase phase command value Cphu, the V-phase phase command value Cphv, and the W-phase phase command value Cphw, and the U-phase amplitude command value Camu, the V-phase amplitude command value Camv, and the W-phase amplitude command value Camw, respectively, of predetermined zero-phase-containing unbalanced three-phase voltages in accordance with the U-phase pulse modulation signal Spu, the V-phase pulse modulation signal Spv, and the W-phase pulse modulation signal Spw from the pulse modulation signal generation circuit 4, thereby outputting an internal zero-phase-containing unbalanced three-phase voltage Vubi including the internal U-phase voltage Viu, the internal V-phase voltage Viv, and the internal W-phase voltage Viw.

[0158] In the three-phase transformer device T, the internal U-phase voltage Viu, the internal V-phase voltage Viv, and the internal W-phase voltage Viw of the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi from the three-phase inverter device INV are input to the primary winding Wuf of the U-phase winding section Tu, the primary winding Wvf of the V-phase winding section Tv, and the primary winding Wwf of the W-phase winding section Tw, respectively.

[0159] Here, the DC power supply DC of the main circuit 2A, the three-phase inverter device INV, and the three-phase transformer device T have respective configurations and mutual connection relationships that enable them to output the zero-phase component of the external zero-phase-containing unbalanced three-phase voltage Vubo, which is obtained by converting the internal zero-phase-containing unbalanced three-phase voltage Vubi in the three-phase transformer device T in accordance with the turns ratio, so that the external zero-phase-containing unbalanced three-phase voltage Vubo is output from the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, the secondary winding Wws of the W-phase winding section Tw, and the secondary winding neutral point Ns, which are Y-connected in the three-phase transformer device T. In addition, the internal zero-phase-containing unbalanced three-phase voltage Vubi or the external zero-phase-containing unbalanced three-phase voltage Vubo is feedback-controlled by a voltage feedback control unit 5.

[0160] 1 and 6, according to the unbalanced three-phase power supply device 100, the phase command values Cphu, Cphv, Cphw and amplitude command values Camu, Camv, Camw for the U, V, and W phases of the received predetermined zero-phase-containing unbalanced three-phase voltage are processed independently for each of the U, V, and W phases in the unbalanced three-phase power supply device 100, so that an external zero-phase-containing unbalanced three-phase voltage Vubo corresponding to the predetermined zero-phase-containing unbalanced three-phase voltage can be generated. Furthermore, the DC power supply DC, the three-phase inverter INV, and the three-phase transformer T have respective configurations and mutual connection relationships that enable them to output the zero-phase component of the generated external zero-phase-containing unbalanced three-phase voltage Vubo, so that the zero-phase component of the external zero-phase-containing unbalanced three-phase voltage Vubo can be output. Therefore, by setting the desired zero-phase-containing three-phase unbalanced voltage to a predetermined zero-phase-containing unbalanced three-phase voltage, it is possible to provide an unbalanced three-phase power supply device 100 that can output a desired unbalanced three-phase voltage Vubo that includes a zero-phase component. Because the unbalanced three-phase power supply device 100 generates the unbalanced three-phase voltage Vubo that includes a zero-phase component using the three-phase inverter device INV, use of the unbalanced three-phase power supply device 100 makes it easy to create a test environment that uses the unbalanced three-phase voltage Vubo that includes a zero-phase component.

[0161] [simulation] In order to confirm the operational effects of the unbalanced three-phase power supply device 100 of the first embodiment, a simulation of the operation of the unbalanced three-phase power supply device 100 was performed. This simulation was performed for the first to fourth zero-phase output configurations of the main circuit 2A using "primary-side control." In these simulations, phase command values Cphu, Cphv, and Cphw and amplitude command values Camu, Camv, and Camw of the U-phase, V-phase, and W-phase of a zero-phase-containing unbalanced three-phase voltage having a waveform shown in the upper waveform diagram of FIG. 7 were input to the voltage command generator 3 as a predetermined zero-phase-containing unbalanced three-phase voltage. In the zero-phase-containing unbalanced three-phase voltage, the amplitude of the V-phase voltage is 50% and the amplitude of the W-phase voltage is 50%, assuming that the amplitude of the U-phase voltage is 100%. The phase difference between the U-phase, V-phase, and W-phase voltages is 120°.

[0162] Fig. 8 is a waveform diagram showing voltage waveforms at various parts of the unbalanced three-phase power supply 100 in a simulation of the unbalanced three-phase power supply 100 in which the main circuit 2A includes the first zero-phase output configuration. Fig. 9 is a waveform diagram showing magnetic flux waveforms of the single-phase transformer of each phase of the three-phase transformer unit in a simulation of the unbalanced three-phase power supply 100 in which the main circuit 2A includes the first zero-phase output configuration. Fig. 10 is a waveform diagram showing magnetic flux waveforms at each leg of the three-phase five-legged core transformer in a simulation of the unbalanced three-phase power supply 100 in which the main circuit 2A includes the second zero-phase output configuration. Fig. 11 is a waveform diagram showing voltage waveforms at various parts of the unbalanced three-phase power supply 100 in a simulation of the unbalanced three-phase power supply 100 in which the main circuit 2A includes the third zero-phase output configuration.

[0163] 8 and 11, the waveform diagrams in the upper rows show the voltage commands of each phase of the voltage command generating unit 3, the waveform diagrams in the middle rows show the values of the output voltages of each phase of the three-phase inverter device INV, and the waveform diagrams in the lower rows show the output voltages of each phase of the three-phase transformer device T. In addition, in each waveform diagram, the solid line shows the U-phase voltage command Cvu or voltages Viu, Vou, the dashed line shows the V-phase voltage command Cvv or voltages Viv, Vov, the one-dot chain line shows the W-phase voltage command Cvw or voltages Viw, Vow, and the two-dot chain line shows the zero-phase component Cv0 of the voltage command or the zero-phase voltages Vi0, Vo0.

[0164] In Fig. 9, the solid line indicates the U-phase magnetic flux Φu, the dashed line indicates the V-phase magnetic flux Φv, and the dashed-dotted line indicates the W-phase magnetic flux Φw. In Fig. 10, the solid line indicates the U-phase magnetic flux Φu, the dashed line indicates the V-phase magnetic flux Φv, the dashed-dotted line indicates the W-phase magnetic flux Φw, and the two-dot-dotted line indicates the zero-phase magnetic fluxes Φ01 and Φ02.

[0165] <1st zero phase output configuration> 8, in the first zero-phase output configuration, the voltage command generating unit 3 outputs a U-phase voltage command Cvu, a V-phase voltage command Cvv, and a W-phase voltage command Cvw corresponding to a predetermined zero-phase-containing unbalanced three-phase voltage, and these U-phase voltage command Cvu, V-phase voltage command Cvv, and W-phase voltage command Cvw include the zero-phase component Cv0. Also, the three-phase inverter device INV is configured with a three-phase inverter unit, and outputs an internal U-phase voltage Viu, an internal V-phase voltage Viv, and an internal W-phase voltage Viw corresponding to the predetermined zero-phase-containing unbalanced three-phase voltage, and these internal U-phase voltage Viu, internal V-phase voltage Viv, and internal W-phase voltage Viw include the internal zero-phase voltage Vi0. It can also be seen that the three-phase transformer device T is composed of a three-phase transformer unit, outputs an external U-phase voltage Vou, an external V-phase voltage Vov, and an external W-phase voltage Vow, and that these external U-phase voltage Vou, external V-phase voltage Vov, and external W-phase voltage Vow include an external zero-sequence voltage Vo0.

[0166] 9, in the first zero-phase output configuration, the three-phase transformer device T, which is made up of three-phase transformer units, generates U-phase magnetic flux Φu, V-phase magnetic flux Φv, and W-phase magnetic flux Φw corresponding to a predetermined zero-phase-containing unbalanced three-phase voltage. In other words, it can be seen that magnetic saturation does not occur in the three-phase transformer device T, even though an unbalanced three-phase magnetic flux including a zero-phase component is generated.

[0167] <Second zero phase output configuration> In the second zero-phase output configuration, the configuration and operation of the three-phase inverter device INV are the same as those in the first zero-phase output configuration, and therefore a description thereof will be omitted.

[0168] 10, in the second zero-phase output configuration, the three-phase transformer T is configured as a three-phase five-leg core transformer, and generates U-phase magnetic flux Φu, V-phase magnetic flux Φv, and W-phase magnetic flux Φw corresponding to a predetermined zero-phase-containing unbalanced three-phase voltage. It can also be seen that magnetic saturation does not occur in the three-phase transformer T. Furthermore, the dashed-double-dot lines indicate the zero-phase magnetic flux Φ01 flowing in the first magnetic leakage leg at one end of the shell core and the zero-phase magnetic flux Φ02 flowing in the second magnetic leakage leg at the other end of the shell core. The zero-phase magnetic flux Φ01 and the zero-phase magnetic flux Φ02 are shown as a single waveform, flowing in the same phase (in the same direction) and canceling each other out.

[0169] <3rd zero phase output configuration> Referring to FIG. 11, in the third zero-phase output configuration, the three-phase inverter device INV is configured as a three-phase inverter, and outputs an internal U-phase voltage Viu, an internal V-phase voltage Viv, and an internal W-phase voltage Viw corresponding to a predetermined zero-phase-containing unbalanced three-phase voltage, and it can be seen that these internal U-phase voltage Viu, internal V-phase voltage Viv, and internal W-phase voltage Viw include the internal zero-phase voltage Vi0.

[0170] In the third zero-phase output configuration, the configuration and operation of the three-phase transformer T are the same as in the first zero-phase output configuration, and therefore a description thereof will be omitted.

[0171] <4th zero phase output configuration> In the fourth zero-phase output configuration, the configuration and operation of the three-phase inverter device INV are the same as those in the third zero-phase output configuration, and therefore a description thereof will be omitted.

[0172] In the fourth zero-phase output configuration, the configuration and operation of the three-phase transformer device T are the same as in the second zero-phase output configuration, and therefore a description thereof will be omitted.

[0173] From the above simulation results, it was confirmed that the unbalanced three-phase power supply device 100 of the first embodiment provides the effects of the present disclosure.

[0174] (Embodiment 2) A second embodiment of the present disclosure illustrates an evaluation power supply including the unbalanced three-phase power supply device 100 of the first embodiment. Fig. 12 is a functional block diagram showing an example of the configuration of the evaluation power supply 1000 according to the second embodiment of the present disclosure.

[0175] 12, the evaluation power supply 1000 includes an input-side three-phase transformer 20 and the unbalanced three-phase power supply 100 of the first embodiment. The input terminal of the input-side three-phase transformer 20 is connected to, for example, a power grid 21. In the unbalanced three-phase power supply 100, a direct-current power supply DC is configured with a converter circuit that converts the three-phase voltage of the power grid input via the input-side three-phase transformer 20 into a direct-current voltage. This converter circuit corresponds to the capacitor of the direct-current power supply DC and the DC power supply in the preceding stage of the converter circuit of the first embodiment. In addition, a device under evaluation 22 is connected to output terminals U, V, W, and n (see FIGS. 2 to 5) on the secondary side of the three-phase transformer T.

[0176] According to this evaluation power supply 1000, the unbalanced three-phase power supply device 100 uses system power from the power grid 21 to supply an external zero-phase-containing unbalanced three-phase voltage Vubo corresponding to an unbalanced three-phase voltage containing a predetermined zero-phase component to the device under evaluation 22. Therefore, it is possible to evaluate the performance of the device under evaluation 22 in response to an unbalanced three-phase voltage containing a zero-phase component in a test environment that can be easily constructed.

[0177] (Embodiment 3)

[0178] [Outline of the structure] 13 is a functional block diagram showing an example of the configuration of an unbalanced three-phase power supply device 200 according to the third embodiment of the present disclosure. Referring to Fig. 13, the unbalanced three-phase power supply device 200 includes a control circuit 1B and a main circuit 2B. The control circuit 1B includes a current command generation unit 6 and a pulse modulation signal generation circuit 7. The main circuit 2B includes a direct current power supply DC, a three-phase inverter device INV, and a three-phase transformer device T.

[0179] The current command generating unit 6 receives unbalanced three-phase current information IFubi including a U-phase phase command value Cphu, a V-phase phase command value Cphv, and a W-phase phase command value Cphw of a zero-phase-containing unbalanced three-phase current, which is an unbalanced three-phase current including a predetermined zero-phase component, and a U-phase amplitude command value Camu, a V-phase amplitude command value Camv, and a W-phase amplitude command value Camw, and generates a U-phase current command Ciu, a V-phase current command Civ, and a W-phase current command Ciw having phases, frequencies, and amplitudes corresponding to the U-phase phase command value Cphu, the V-phase phase command value Cphv, and the W-phase phase command value Cphw of the predetermined zero-phase-containing unbalanced three-phase current, and the U-phase amplitude command value Camu, the V-phase amplitude command value Camv, and the W-phase amplitude command value Camw, respectively, based on the unbalanced three-phase current information IFubi.

[0180] The pulse modulation signal generation circuit 7 outputs a U-phase pulse modulation signal Spu, a V-phase pulse modulation signal Spv, and a W-phase pulse modulation signal Spw corresponding to the U-phase current command Ciu, the V-phase current command Civ, and the W-phase current command Ciw generated by the current command generation unit 6.

[0181] The direct current power supply DC outputs a predetermined direct current voltage or current.

[0182] The three-phase inverter device INV includes a U-phase inverter unit INVu (see FIG. 14), a V-phase inverter unit INVv (see FIG. 14), and a W-phase inverter unit INVw (see FIG. 14). The U-phase inverter unit INVu, the V-phase inverter unit INVv, and the W-phase inverter unit INVw generate predetermined DC voltages or DC currents from a DC power supply DC in accordance with a U-phase pulse modulation signal Spu, a V-phase pulse modulation signal Spv, and a W-phase pulse modulation signal Spw from a pulse modulation signal generation circuit 7, respectively. The internal zero-phase-sequence-containing unbalanced three-phase current Iubi is generated, which has a phase, frequency, and amplitude corresponding to the U-phase phase command value Cphu, the V-phase phase command value Cphv, and the W-phase phase command value Cphw, and the U-phase amplitude command value Camu, the V-phase amplitude command value Camv, and the W-phase amplitude command value Camw, respectively, of the zero-phase-sequence-containing unbalanced three-phase current Iubi, thereby outputting the internal zero-phase-sequence-containing unbalanced three-phase current Iubi including the internal U-phase current Iiu, the internal V-phase current Iiv, and the internal W-phase current Iiw.

[0183] The three-phase transformer device T includes a U-phase winding section Tu (see FIG. 14), a V-phase winding section Tv (see FIG. 14), a W-phase winding section Tw (see FIG. 14), and a secondary winding neutral point Ns (see FIG. 14). The secondary winding Wus (see FIG. 14) of the U-phase winding section Tu, the secondary winding Wvs (see FIG. 14) of the V-phase winding section Tv, and the secondary winding Wws (see FIG. 14) of the W-phase winding section Tw are Y-connected, and the secondary winding neutral point Ns is the neutral point of the Y-connection. The internal U-phase current Iiu, internal V-phase current Iiv, and internal W-phase current Iiw of the internal zero-phase-sequence-containing unbalanced three-phase current Iubi from the three-phase inverter device INV are input to the primary winding Wuf (see FIG. 14) of the U-phase winding section Tu, the primary winding Wvf (see FIG. 14) of the V-phase winding section Tv, and the primary winding Wwf (see FIG. 14) of the W-phase winding section Tw, respectively.

[0184] The DC power supply DC of the main circuit 2B, the three-phase inverter device INV, and the three-phase transformer device T have respective configurations and mutual connection relationships that enable them to output the zero-phase component of the external zero-phase-containing unbalanced three-phase current Iubo, which is obtained by converting the internal zero-phase-containing unbalanced three-phase current Iubi in the three-phase transformer device T in accordance with the turns ratio of the three-phase transformer device T. The external zero-phase-containing unbalanced three-phase current Iubo is output by the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, the secondary winding Wws of the W-phase winding section Tw, and the secondary winding neutral point Ns, which are all Y-connected in the three-phase transformer device T. The external zero-sequence-containing unbalanced three-phase current Iubo includes an external U-phase current Iou, an external V-phase current Iov, and an external W-phase current Iow, which are obtained by converting the internal U-phase current Iiu, the internal V-phase current Iiv, and the internal W-phase current Iiw of the internal zero-sequence-containing unbalanced three-phase current Iubi according to the turns ratio.

[0185] The control of the internal zero-sequence-containing unbalanced three-phase current Iubi or the external zero-sequence-containing unbalanced three-phase current Iubo may be either feedforward control or feedback control. The configuration when feedforward control is performed is roughly as described above.

[0186] When feedback control is performed, a current feedback control unit 8 (see FIG. 18 ) is provided in the control circuit 1B between the current command generation unit 6 and the pulse modulated signal generation circuit 7. The current feedback control unit 8 generates a U-phase current control input Oiu, a V-phase current control input Oiv, and a W-phase current control input Oiw based on errors of the internal U-phase current Iiu, the internal V-phase current Iiv, and the internal W-phase current Iiw of the internal zero-sequence-containing unbalanced three-phase current Iubi relative to the U-phase current command Ciu, the V-phase current command Civ, and the W-phase current command Ciw from the current command generation unit 6, or generates a U-phase current control input Oiu, a V-phase current control input Oiv, and a W-phase current control input Oiw based on errors of the external U-phase current Iou, the external V-phase current Iov, and the external W-phase current Iow of the external zero-sequence-containing unbalanced three-phase current Iubo relative to the U-phase current command Ciu, the V-phase current command Civ, and the W-phase current command Ciw from the current command generation unit 6. The pulse modulation signal generation circuit 7 outputs a U-phase pulse modulation signal Spu, a V-phase pulse modulation signal Spv, and a W-phase pulse modulation signal Spw, which correspond to the U-phase current control input Oiu, the V-phase current control input Oiv, and the W-phase current control input Oiw, which are generated by the current feedback control unit 8.

[0187] [Advanced Configuration] The detailed configuration of the unbalanced three-phase power supply device 200 will be described below, starting with the main circuit 2B and then the control circuit 1B. A circuit configuration in which the pulse modulation signal is a PWM signal will be exemplified below. A circuit configuration in which the pulse modulation signal is a pulse modulation signal other than a PWM signal can also be constructed by replacing the circuit that generates the PWM signal shown in pulse modulation signal generation circuit 7 in FIG. 18 with a circuit that generates a pulse modulation signal other than a PWM signal. In the following, a PWM signal will be referred to as a pulse modulation signal, which is a broader concept.

[0188] {Main circuit 2B} 13 to 17, the main circuit 2B requires that "the DC power supply DC, the three-phase inverter INV, and the three-phase transformer T have respective configurations and mutual connection relationships that enable them to output the zero-phase component of the external zero-phase-containing unbalanced three-phase current Iubo, which is obtained by converting the internal zero-phase-containing unbalanced three-phase current Iubi in the three-phase transformer T in accordance with the turns ratio of the three-phase transformer T." Hereinafter, this requirement will be referred to as the "zero-phase-output capability requirement." The zero-phase-output capability requirement includes the following four items:

[0189] a. Each phase can be controlled individually, and the main circuits of each phase are independent (this does not mean that they are isolated).

[0190] b. The transformer is independent or has a shell-type five-legged core.

[0191] c. In the transformer, at least the secondary side is Y-connected and has a neutral point (a typical Y / Y connection requires a △ winding to suppress third harmonics, but this is not necessary in this case).

[0192] The following four types of circuit configurations have been identified as realistic main circuits 2B that satisfy the zero-phase output capability requirement.

[0193] 5th Zero-Phase Output Configuration: 3 Single-Phase Inverters + 3 Single-Phase Transformers 6th Zero-Phase Output Configuration: 3 Single-Phase Inverters + 1 Three-Phase Five-Leg Transformer 7th Zero-phase Output Configuration: One three-phase four-wire inverter + three single-phase transformers 8th zero-phase output configuration: one three-phase four-wire inverter + one three-phase five-leg core transformer Here, please note the following. As is clear from the above-mentioned "zero-phase output capability requirements," the fifth to eighth zero-phase output configurations specify only combinations of a direct-current power supply DC, a three-phase inverter INV, and a three-phase transformer T. Meanwhile, Figs. 13 to 17, which are used to explain the fifth to eighth zero-phase output configurations, show low-pass filters Flu, Flv, and Flw, a voltage sensor unit SEv, and a current sensor unit SEi in addition to the direct-current power supply DC, a three-phase inverter INV, and a three-phase transformer T. However, the low-pass filters Flu, Flv, and Flw, the voltage sensor unit SEv, and the current sensor unit SEi are elements unrelated to the "zero-phase output capability requirements," and are not included in the fifth to eighth zero-phase output configurations.

[0194] The low-pass filters Flu, Flv, and Flw are provided to remove the carrier frequency component of the pulse modulated signal from the voltage (internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi or external zero-phase-sequence-containing unbalanced three-phase voltage Vubo (see Figure 1)) output from the three-phase inverter device INV. Each of the low-pass filters Flu, Flv, and Flw is composed of a reactor and a capacitor arranged on the output side of the reactor. Generally, the reactor is arranged on the primary side of the three-phase transformer T, and the capacitor is arranged on the primary or secondary side of the three-phase transformer T. A configuration in which the capacitor is arranged on the primary side of the three-phase transformer T is called "primary-side control," and a configuration in which the capacitor is arranged on the secondary side of the three-phase transformer T is called "secondary-side control." However, if the three-phase transformer T is composed of a leakage transformer, the reactor is omitted and the capacitor is arranged on the secondary side of the three-phase transformer T, resulting in "secondary-side control."

[0195] The control target of the "primary side control" and "secondary side control" is the voltage output from the three-phase inverter device INV (the internal zero-phase-containing unbalanced three-phase voltage Vubi or the external zero-phase-containing unbalanced three-phase voltage Vubo). Therefore, in the case of "primary side control," the voltage sensor unit SEv is provided on the output side of the capacitor of the low-pass filter on the primary side of the three-phase transformer device T to detect the internal zero-phase-containing unbalanced three-phase voltage Vubi. In the case of "secondary side control," the voltage sensor unit SEv is provided on the output side of the capacitor of the low-pass filter on the secondary side of the three-phase transformer device T to detect the external zero-phase-containing unbalanced three-phase voltage Vubo. Note that although the voltage output from the three-phase inverter device INV is not explicitly controlled in the third embodiment, it is appropriately controlled because it is used to generate a reference internal sine wave for each phase and to extract the phase of the reference internal sine wave for each phase, as described below.

[0196] The current sensor unit SEi is used to control the current (internal zero-phase-sequence-containing unbalanced three-phase current Iubi or external zero-phase-sequence-containing unbalanced three-phase current Iubo) output from the three-phase inverter device INV.

[0197] The main circuits 2B including the fifth to eighth zero-phase output configurations will be described below in order.

[0198] ≪5th zero phase output configuration≫ Fig. 14 is a circuit diagram showing details of the main circuit 2B including the fifth zero-phase output configuration in Fig. 13. Hereinafter, the contents of the main circuit 2B including the fifth zero-phase output configuration will be described with reference to Fig. 14.

[0199] <DC power supply DC> The DC power supply DC includes a U-phase DC power supply unit DCu, a V-phase DC power supply unit DCv, and a W-phase DC power supply unit DCw, each of which outputs a predetermined DC voltage or DC current. Here, the U-phase DC power supply unit DCu, the V-phase DC power supply unit DCv, and the W-phase DC power supply unit DCw are connected in parallel with each other, but may be independent of each other. The U-phase DC power supply unit DCu, the V-phase DC power supply unit DCv, and the W-phase DC power supply unit DCw are not particularly limited as long as they are DC voltage sources capable of outputting a predetermined DC voltage or DC current, respectively. Examples of the U-phase DC power supply unit DCu, the V-phase DC power supply unit DCv, and the W-phase DC power supply unit DCw include capacitors, DC / DC converters, rectifiers, and rechargeable batteries. Here, the U-phase DC power supply unit DCu, the V-phase DC power supply unit DCv, and the W-phase DC power supply unit DCw are each configured as a capacitor. In this case, a DC power supply device (not shown) is provided in front of these three capacitors to charge the three capacitors.

[0200] <Three-phase inverter INV> The three-phase inverter device INV includes a U-phase inverter section INVu, a V-phase inverter section INVv, and a W-phase inverter section INVw. The three-phase inverter device INV is configured as a three-phase inverter unit. The three-phase inverter unit includes a single-phase U-phase inverter that constitutes the U-phase inverter section INVu, a single-phase V-phase inverter that constitutes the V-phase inverter section INVv, and a single-phase W-phase inverter that constitutes the W-phase inverter section INVw. The single-phase U-phase inverter, the single-phase V-phase inverter, and the single-phase W-phase inverter are not particularly limited as long as they can convert DC voltage or DC current into AC current. The single-phase U-phase inverter, the single-phase V-phase inverter, and the single-phase W-phase inverter are each configured as, for example, a full-bridge inverter. Full-bridge inverters are well known, so they will be briefly described below.

[0201] The U-phase inverter has four switching elements Q1u to Q4u connected in a full bridge. The input terminal of the U-phase inverter is connected to a U-phase DC power supply unit DCu. A U-phase positive-phase pulse modulated signal Spup constituting a U-phase pulse modulated signal Spu from the pulse modulated signal generation circuit 7 is input to the pair of switching element Q1u and switching element Q2u, and a U-phase negative-phase pulse modulated signal Spuo constituting the U-phase pulse modulated signal Spu from the pulse modulated signal generation circuit 7 is input to the pair of switching element Q3u and switching element Q4u. The U-phase inverter alternately turns on and off a pair of switching elements Q1u and Q2u in accordance with a U-phase positive-phase pulse modulation signal Spup and a pair of switching elements Q3u and Q4u in accordance with a U-phase negative-phase pulse modulation signal Spuo, thereby using a predetermined DC voltage or DC current from the U-phase DC power supply unit DCu to generate an internal U-phase current Iiu having a phase, frequency, and amplitude corresponding to a U-phase phase command value Cphu and an amplitude command value Camu of a predetermined zero-phase-containing unbalanced three-phase current, and outputs the internal U-phase current Iiu from the output terminal.

[0202] The V-phase inverter has four switching elements Q1v to Q4v connected in a full bridge. The input terminal of the V-phase inverter is connected to a V-phase DC power supply unit DCv. A V-phase positive-phase pulse modulated signal Spvp that constitutes a V-phase pulse modulated signal Spv from the pulse modulated signal generation circuit 7 is input to the pair of switching element Q1v and switching element Q2v, and a V-phase negative-phase pulse modulated signal Spvo that constitutes a V-phase pulse modulated signal Spv from the pulse modulated signal generation circuit 7 is input to the pair of switching element Q3v and switching element Q4v. The V-phase inverter alternately turns on and off a pair of switching elements Q1v and Q2v in accordance with a V-phase positive-phase pulse modulation signal Spvp and a pair of switching elements Q3v and Q4v in accordance with a V-phase negative-phase pulse modulation signal Spvo, thereby using a predetermined DC voltage or DC current from a V-phase DC power supply unit DCv to generate an internal V-phase current Iiv having a phase, frequency, and amplitude corresponding to a V-phase phase command value Cphv and an amplitude command value Camv of a predetermined zero-phase-containing unbalanced three-phase current, and outputs the internal V-phase current Iiv from the output terminal.

[0203] The W-phase inverter has four switching elements Q1w to Q4w connected in a full bridge. The input terminal of the W-phase inverter is connected to a W-phase DC power supply unit DCw. A W-phase positive-phase pulse modulated signal Spwp constituting the W-phase pulse modulated signal Spw from the pulse modulated signal generation circuit 7 is input to the pair of switching element Q1w and switching element Q2w, and a W-phase negative-phase pulse modulated signal Spwo constituting the W-phase pulse modulated signal Spw from the pulse modulated signal generation circuit 7 is input to the pair of switching element Q3w and switching element Q4w. The W-phase inverter alternately turns on and off a pair of switching elements Q1w and Q2w in accordance with the W-phase positive-phase pulse modulation signal Spwp and a pair of switching elements Q3w and Q4w in accordance with the W-phase negative-phase pulse modulation signal Spwo, thereby using a predetermined DC voltage or DC current from the W-phase DC power supply unit DCw to generate an internal W-phase current Iiw having a phase, frequency, and amplitude corresponding to a W-phase phase command value Cphw and an amplitude command value Camw of a predetermined zero-phase-containing unbalanced three-phase current, and outputs the internal W-phase current Iiw from the output terminal.

[0204] In this way, the U-phase inverter, the V-phase inverter, and the W-phase inverter output the internal zero-phase-containing unbalanced three-phase current Iubi, which includes the internal U-phase current Iiu, the internal V-phase current Iiv, and the internal W-phase current Iiw as the U-phase current, the V-phase current, and the W-phase current, respectively.

[0205] <Three-phase transformer T> The three-phase transformer device T includes a U-phase winding section Tu, a V-phase winding section Tv, and a W-phase winding section Tw. The U-phase winding section Tu, the V-phase winding section Tv, and the W-phase winding section Tw have a common predetermined turns ratio. This also applies to the sixth to eighth zero-phase output configurations.

[0206] The three-phase transformer device T is composed of a three-phase transformer unit. The three-phase transformer unit includes a single-phase U-phase transformer that constitutes the U-phase winding section Tu, a single-phase V-phase transformer that constitutes the V-phase winding section Tv, and a single-phase W-phase transformer that constitutes the W-phase winding section Tw.

[0207] The primary winding Wuf of the U-phase transformer is connected to the output terminal of the U-phase inverter via a low-pass filter Flu. The primary winding Wvf of the V-phase transformer is connected to the output terminal of the V-phase inverter via a low-pass filter Flv. The primary winding Wwf of the W-phase transformer is connected to the output terminal of the W-phase inverter via a low-pass filter Flw.

[0208] The secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, and the secondary winding Wws of the W-phase transformer are star-connected at the secondary winding neutral point Ns.

[0209] In the three-phase transformer unit, the internal U-phase current Iiu, internal V-phase current Iiv, and internal W-phase current Iiw of the internal zero-phase-sequence-containing unbalanced three-phase current Iubi from the three-phase inverter unit are input to the primary winding Wuf of the U-phase transformer, the primary winding Wvf of the V-phase transformer, and the primary winding Wwf of the W-phase transformer, respectively. The internal U-phase current Iiu, internal V-phase current Iiv, and internal W-phase current Iiw are converted in the secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, and the secondary winding Wws of the W-phase transformer according to a predetermined turns ratio to generate the external zero-phase-sequence-containing unbalanced three-phase current Iubo, which includes the external U-phase current Iou, the external V-phase current Iov, and the external W-phase current Iow. This external zero-phase-sequence-containing unbalanced three-phase current Iubo is output by the secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, the secondary winding Wws of the W-phase transformer, and the secondary winding neutral point Ns, which are all connected in a Y-connection in the three-phase transformer unit. Reference symbols U, V, W, and n denote the U-phase, V-phase, W-phase, and zero-phase output terminals on the secondary side of the three-phase transformer unit, respectively.

[0210] <Elements other than the 5th zero-phase output configuration> *Low pass filter* Here, the low-pass filters are configured in a "primary side control" configuration. A U-phase low-pass filter Flu is arranged between the output terminal of the U-phase inverter and the primary winding Wuf of the U-phase transformer. A V-phase low-pass filter Flv is arranged between the output terminal of the V-phase inverter and the primary winding Wvf of the V-phase transformer. A W-phase low-pass filter Flw is arranged between the output terminal of the W-phase inverter and the primary winding Wwf of the W-phase transformer. The low-pass filters may also be configured in a "secondary side control" configuration.

[0211] *Voltage sensor unit SEv* A U-phase voltage sensor SEvu is provided across both ends of the primary winding Wuf of the U-phase transformer to detect the internal U-phase voltage Viu. A V-phase voltage sensor SEvv is provided across both ends of the primary winding Wvf of the V-phase transformer to detect the internal V-phase voltage Viv. A W-phase voltage sensor SEvw is provided across both ends of the primary winding Wwf of the W-phase transformer to detect the internal W-phase voltage Viw. The U-phase voltage sensor SEvu, V-phase voltage sensor SEvv, and W-phase voltage sensor SEvw constitute a voltage sensor unit SEv that detects the internal zero-phase-containing unbalanced three-phase voltage Vubi. Here, the voltage sensor unit SEv is provided to correspond to "primary side control." In the case of "secondary side control," the voltage sensor unit SEv is provided on the output side of the capacitor of the low-pass filter on the secondary side of the three-phase transformer unit. The internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi detected by the voltage sensor unit SEv is used to generate a reference internal three-phase sine wave for each phase and to extract the phase of the reference internal sine wave for each phase in the reference internal three-phase sine wave generating unit, as will be described later. This also applies to the sixth to eighth zero-phase output configurations.

[0212] *Current Sensor Unit SEi* A U-phase current sensor SEiu is provided in the wiring between the output terminal of the U-phase inverter and the low-pass filter Flu to detect the internal U-phase current Iiu. A V-phase current sensor SEiv is provided in the wiring between the output terminal of the V-phase inverter and the low-pass filter Flv to detect the internal V-phase current Iiv. A W-phase current sensor SEiw is provided in the wiring between the output terminal of the W-phase inverter and the low-pass filter Flw to detect the internal W-phase current Iiw. The U-phase current sensor SEiu, V-phase current sensor SEiv, and W-phase current sensor SEiw constitute a current sensor unit SEi that detects the internal zero-sequence-containing unbalanced three-phase current Iubi. Note that the current sensor unit SEi may also be configured to detect the external zero-sequence-containing unbalanced three-phase current Iubo.

[0213] <Action and effect> According to this fifth zero-phase output configuration, an internal zero-phase-containing unbalanced three-phase current Iubi is generated in the main circuit 2B. However, the DC power supply DC, the three inverter sections INVu to INVw of the three-phase inverter device INV, and the three winding sections Tu to Tw of the three-phase transformer device corresponding to the three phases are respectively configured by three DC power supply sections DCu to DCw of the DC power supply DC, three single-phase inverters of the three-phase inverter unit, and three single-phase transformers of the three-phase transformer unit, which are independent of one another. Therefore, the current of the zero-phase component of the internal zero-phase-containing unbalanced three-phase current Iubi flows through the DC power supply sections DCu to DCw, the single-phase inverters, and the primary windings Wuf to Wwf of the single-phase transformers corresponding to each phase, respectively, in accordance with the phase currents Iiu to Iiw of the three phases, which are unbalanced with one another. Furthermore, since the secondary windings Wus-Wws of the single-phase transformers corresponding to the three phases are Y-connected, the external zero-phase-containing unbalanced three-phase current Iubo, which is obtained by converting the internal zero-phase-containing unbalanced three-phase current Iubi in accordance with the turns ratio, is output by the secondary windings Wus-Wws and secondary winding neutral point Ns of the Y-connected single-phase transformers corresponding to the three phases. As a result, it is possible to suitably configure a combination of a DC power supply DC, a three-phase inverter device INV, and a three-phase transformer device T that is capable of outputting the zero-phase component of the external zero-phase-containing unbalanced three-phase current Iubo.

[0214] ≪6th zero phase output configuration≫ Fig. 15 is a circuit diagram showing details of the main circuit 2B including the sixth zero-phase output configuration in Fig. 13. Hereinafter, the contents of the main circuit 2B including the sixth zero-phase output configuration will be described with reference to Fig. 15.

[0215] <DC power supply DC> The direct current power supply DC of the sixth zero-phase output configuration is the same as the direct current power supply DC of the fifth zero-phase output configuration, and therefore a description thereof will be omitted.

[0216] <Three-phase inverter INV> The three-phase inverter device INV of the sixth zero-phase output configuration is the same as the three-phase inverter device INV of the fifth zero-phase output configuration, and therefore a description thereof will be omitted.

[0217] <Three-phase transformer T> The three-phase transformer device T is configured with a three-phase five-legged core transformer. Three-phase five-legged core transformers are well known, so only a brief description will be given. The three-phase five-legged core transformer includes a three-phase five-legged core (not shown) having a U-leg, a V-leg, a W-leg, and a pair of magnetic leakage legs provided on both sides of the U-leg, the V-leg, and the W-leg, a U-phase winding section Tu provided on the U-phase leg, a V-phase winding section Tv provided on the V-phase leg, and a W-phase winding section Tw provided on the W-phase leg.

[0218] The primary winding Wuf of the U-phase winding section Tu is connected to the output terminal of the U-phase inverter via a low-pass filter Flu. The primary winding Wvf of the V-phase winding section Tv is connected to the output terminal of the V-phase inverter via a low-pass filter Flv. The primary winding Wwf of the W-phase winding section Tw is connected to the output terminal of the W-phase inverter via a low-pass filter Flw.

[0219] The secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, and the secondary winding Wws of the W-phase winding section Tw are star-connected at the secondary winding neutral point Ns.

[0220] In a three-phase five-legged transformer, the internal U-phase current Iiu, internal V-phase current Iiv, and internal W-phase current Iiw of the internal zero-phase-sequence-containing unbalanced three-phase current Iubi from the three-phase inverter unit are input to the primary winding Wuf of the U-phase winding section Tu, the primary winding Wvf of the V-phase winding section Tv, and the primary winding Wwf of the W-phase winding section Tw, respectively. The internal U-phase current Iiu, internal V-phase current Iiv, and internal W-phase current Iiw are converted according to a predetermined turns ratio in the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, and the secondary winding Wws of the W-phase winding section Tw to generate an external zero-phase-sequence-containing unbalanced three-phase current Iubo including an external U-phase current Iou, an external V-phase current Iov, and an external W-phase current Iow. This external zero-phase-sequence-containing unbalanced three-phase current Iubo is output by the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, the secondary winding Wws of the W-phase winding section Tw, and the secondary winding neutral point Ns, which are all connected in a Y-connection of the three-phase five-leg core transformer. Reference symbols U, V, W, and n denote the U-phase, V-phase, W-phase, and zero-phase output terminals on the secondary side of the three-phase five-leg core transformer, respectively.

[0221] <Elements other than the 6th zero-phase output configuration> *Low pass filter* Here, the low-pass filters are configured for "primary side control." A U-phase low-pass filter Flu is arranged between the output terminal of the U-phase inverter and the primary winding Wuf of the U-phase winding section Tu. A V-phase low-pass filter Flv is arranged between the output terminal of the V-phase inverter and the primary winding Wvf of the V-phase winding section Tv. A W-phase low-pass filter Flw is arranged between the output terminal of the W-phase inverter and the primary winding Wwf of the W-phase winding section Tw. The low-pass filters may also be configured for "secondary side control."

[0222] *Voltage sensor unit SEv* A U-phase voltage sensor SEvu is provided across both ends of the primary winding Wuf of the U-phase winding section Tu to detect the internal U-phase voltage Viu. A V-phase voltage sensor SEvv is provided across both ends of the primary winding Wvf of the V-phase winding section Tv to detect the internal V-phase voltage Viv. A W-phase voltage sensor SEvw is provided across both ends of the primary winding Wwf of the W-phase winding section Tw to detect the internal W-phase voltage Viw. The U-phase voltage sensor SEvu, V-phase voltage sensor SEvv, and W-phase voltage sensor SEvw constitute a voltage sensor unit SEv that detects the internal zero-phase-containing unbalanced three-phase voltage Vubi. Here, the voltage sensor unit SEv is provided to correspond to "primary side control." In the case of "secondary side control," the voltage sensor unit SEv is provided on the output side of the capacitor of the low-pass filter on the secondary side of the three-phase five-legged core transformer.

[0223] <Current sensor unit SEi> The current sensor unit SEi of the sixth zero-phase output configuration is the same as the current sensor unit SEi of the fifth zero-phase output configuration, and therefore a description thereof will be omitted.

[0224] <Action and effect> According to this sixth zero-phase output configuration, an internal zero-phase-containing unbalanced three-phase current Iubi is generated in the main circuit 2B. However, the DC power supply DC, the three inverter units INVu to INVw of the three-phase inverter device INV, and the three winding units Tu to Tw of the three-phase five-leg core transformer corresponding to the three phases are respectively configured by three DC power supply units DCu to DCw of the DC power supply DC, three single-phase inverters of the three-phase inverter unit, and three winding units Tu to Tw of the three-phase five-leg core transformer that are independent of one another. Therefore, the current of the zero-phase component of the internal zero-phase-containing unbalanced three-phase current Iubi flows through the DC power supply units DCu to DCw, the single-phase inverters, and the primary windings Wuf to Wwf of the winding units Tu to Tw of the three-phase five-leg core transformer corresponding to each phase, respectively, in accordance with the phase currents Iiu to Iiw of the three phases that are unbalanced with one another. The secondary windings Wus-Wws of the winding sections Tu-Tw of the three-phase five-leg core transformer corresponding to the three phases are Y-connected, and the external zero-phase-containing unbalanced three-phase current Iubo, which is obtained by converting the internal zero-phase-containing unbalanced three-phase current Iubi according to the turns ratio, is output by the secondary windings Wus-Wws and secondary winding neutral point Ns of the winding sections Tu-Tw of the three-phase five-leg core transformer corresponding to the Y-connected three phases. In this case, the zero-phase magnetic flux passes through a pair of magnetic leakage legs. As a result, a suitable combination of a DC power supply DC, a three-phase inverter device INV, and a three-phase transformer device T can be constructed that can output the zero-phase component of the external zero-phase-containing unbalanced three-phase current Iubo.

[0225] <Main circuit 2B including 7th zero-phase output configuration> Fig. 16 is a circuit diagram showing details of the main circuit 2B including the seventh zero-phase output configuration in Fig. 13. Hereinafter, the contents of the main circuit 2B including the seventh zero-phase output configuration will be described with reference to Fig. 16.

[0226] <DC power supply DC> The DC power supply DC includes a positive DC power supply unit DCp and a negative DC power supply unit DCn, which are connected in series with each other at a power supply neutral point Ndc and each output a predetermined DC voltage. The positive DC power supply unit DCp and the negative DC power supply unit DCn are not particularly limited as long as they are a DC voltage source capable of outputting a predetermined DC voltage or a DC current source capable of outputting a predetermined DC current. Examples of the positive DC power supply unit DCp and the negative DC power supply unit DCn include a capacitor, a DC / DC converter, a rectifier, and a rechargeable battery. Here, the positive DC power supply unit DCp and the negative DC power supply unit DCn are each composed of a capacitor. In this case, a DC power supply device (not shown) is provided in front of this pair of capacitors to charge the pair of capacitors.

[0227] <Three-phase inverter INV> The three-phase inverter device INV is configured as a three-phase, four-wire inverter. The three-phase, four-wire inverter may be a three-phase, four-wire inverter, and the configuration of the inverter unit (switching unit) is not particularly limited. The three-phase, four-wire inverter includes, for example, a U-phase inverter unit INVu consisting of a half-bridge, a V-phase inverter unit INVv consisting of a half-bridge, and a W-phase inverter unit INVw consisting of a half-bridge. Half-bridge type three-phase, four-wire inverters are well known, so they will be briefly described below.

[0228] The U-phase inverter unit INVu has two switching elements Q1u and Q2u connected to half-ridges. In the U-phase inverter unit INVu, the positive input terminal is connected to the positive terminal of the positive DC power supply unit DCp, and the negative input terminal is connected to the negative terminal of the negative DC power supply unit DCn. A U-phase positive-phase pulse modulated signal Spup and a U-phase negative-phase pulse modulated signal Spuo, which constitute the U-phase pulse modulated signal Spu from the pulse modulated signal generation circuit 7, are input to the switching element Q1u and the switching element Q2u, respectively. The U-phase inverter unit INVu alternately turns on and off a switching element Q1u in accordance with a U-phase positive-phase pulse modulation signal Spup and a switching element Q2u in accordance with a U-phase negative-phase pulse modulation signal Spuo, thereby using a predetermined DC voltage or DC current from the positive DC power supply unit DCp and the negative DC power supply unit DCn to generate an internal U-phase current Iiu having a phase, frequency, and amplitude corresponding to a U-phase phase command value Cphu and an amplitude command value Camu of a predetermined zero-phase-containing unbalanced three-phase current, and outputs the internal U-phase current Iiu from an output terminal.

[0229] The V-phase inverter section INVv has two switching elements Q1v and Q2v connected to half-ridges. In the V-phase inverter section INVv, the positive input terminal is connected to the positive terminal of the positive DC power supply section DCp, and the negative input terminal is connected to the negative terminal of the negative DC power supply section DCn. A V-phase positive-phase pulse modulated signal Spvp and a V-phase negative-phase pulse modulated signal Spvo that constitute the V-phase pulse modulated signal Spv from the pulse modulated signal generation circuit 7 are input to switching element Q1v and switching element Q2v, respectively. The V-phase inverter unit INVv alternately turns on and off a switching element Q1v in accordance with a V-phase positive-phase pulse modulation signal Spvp and a switching element Q2v in accordance with a V-phase negative-phase pulse modulation signal Spvo, thereby using a predetermined DC voltage or DC current from the positive DC power supply unit DCp and the negative DC power supply unit DCn to generate an internal V-phase current Iiv having a phase, frequency, and amplitude corresponding to a V-phase phase command value Cphv and an amplitude command value Camv of a predetermined zero-phase-containing unbalanced three-phase current, and outputs the internal V-phase current Iiv from an output terminal.

[0230] The W-phase inverter section INVw has two switching elements Q1w and Q2w connected to half-ridges. In the W-phase inverter section INVw, the positive input terminal is connected to the positive terminal of the positive DC power supply section DCp, and the negative input terminal is connected to the negative terminal of the negative DC power supply section DCn. A W-phase positive-phase pulse modulated signal Spwp and a W-phase negative-phase pulse modulated signal Spwo, which constitute the W-phase pulse modulated signal Spw from the pulse modulated signal generation circuit 7, are input to switching element Q1w and switching element Q2w, respectively. The W-phase inverter unit INVw alternately turns on and off a switching element Q1w in accordance with the W-phase positive-phase pulse modulation signal Spwp and a switching element Q2w in accordance with the W-phase negative-phase pulse modulation signal Spwo, thereby using a predetermined DC voltage or DC current from the positive DC power supply unit DCp and the negative DC power supply unit DCn to generate an internal W-phase current Iiw having a phase, frequency, and amplitude corresponding to a W-phase phase command value Cphw and an amplitude command value Camw of a predetermined zero-phase-containing unbalanced three-phase current, and outputs the internal W-phase current Iiw from an output terminal.

[0231] In this way, the U-phase inverter unit INVu, the V-phase inverter unit INVv, and the W-phase inverter unit INVw output the internal zero-phase-containing unbalanced three-phase current Iubi, which includes the internal U-phase current Iiu, the internal V-phase current Iiv, and the internal W-phase current Iiw as the U-phase current, the V-phase current, and the W-phase current, respectively.

[0232] <Three-phase transformer T> Since the three-phase transformer T with the seventh zero-phase output configuration is similar to the three-phase transformer T with the fifth zero-phase output configuration, only the differences between the three-phase transformer T with the seventh zero-phase output configuration and the three-phase transformer T with the fifth zero-phase output configuration will be explained.

[0233] In the seventh zero-phase output configuration, the primary winding Wuf of the U-phase transformer is connected to the output terminal of the U-phase inverter unit INVu via a low-pass filter Flu. The primary winding Wvf of the V-phase transformer is connected to the output terminal of the V-phase inverter unit INVv via a low-pass filter Flv. The primary winding Wwf of the W-phase transformer is connected to the output terminal of the W-phase inverter unit INVw via a low-pass filter Flw.

[0234] The primary winding Wuf of the U-phase transformer, the primary winding Wvf of the V-phase transformer, and the primary winding Wwf of the W-phase transformer are Y-connected at the primary winding neutral point Nf. The primary winding neutral point Nf is connected to the power supply neutral point Ndc, for example, by a neutral wire Wn. Note that the primary winding neutral point Nf and the power supply neutral point Ndc may be grounded, thereby connecting the primary winding neutral point Nf to the power supply neutral point Ndc. As a result, the U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw of the three-phase four-wire inverter are Y-connected at the power supply neutral point Ndc via a common positive DC power supply section DCp and negative DC power supply section DCn, and the Y-connected U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw and positive DC power supply section DCp and negative DC power supply section DCn are Y / Y-connected with the U-phase transformer, V-phase transformer, and W-phase transformer of the Y-connected three-phase transformer unit.

[0235] The secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, and the secondary winding Wws of the W-phase transformer are star-connected at the secondary winding neutral point Ns.

[0236] In the three-phase transformer unit, the internal U-phase current Iiu, internal V-phase current Iiv, and internal W-phase current Iiw of the internal zero-phase-sequence-containing unbalanced three-phase current Iubi from the three-phase four-wire inverter are input to the primary winding Wuf of the U-phase transformer, the primary winding Wvf of the V-phase transformer, and the primary winding Wwf of the W-phase transformer, respectively. The internal U-phase current Iiu, internal V-phase current Iiv, and internal W-phase current Iiw are converted in the secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, and the secondary winding Wws of the W-phase transformer according to a predetermined turns ratio to generate the external zero-phase-sequence-containing unbalanced three-phase current Iubo, which includes the external U-phase current Iou, the external V-phase current Iov, and the external W-phase current Iow. This external zero-phase-sequence-containing unbalanced three-phase current Iubo is then output by the secondary winding Wus of the U-phase transformer, the secondary winding Wvs of the V-phase transformer, the secondary winding Wws of the W-phase transformer, and the secondary winding neutral point Ns, which are all connected in a Y-connection in the three-phase transformer unit.

[0237] <Elements other than the 7th zero-phase output configuration> *Low pass filter* Here, the low-pass filters are configured in a "primary side control" configuration. A U-phase low-pass filter Flu is arranged between the primary winding Wuf of the U-phase transformer and the output terminal of the U-phase inverter unit INVu. A V-phase low-pass filter Flv is arranged between the primary winding Wvf of the V-phase transformer and the output terminal of the V-phase inverter unit INVv. A W-phase low-pass filter Flw is arranged between the primary winding Wwf of the W-phase transformer and the output terminal of the W-phase inverter unit INVw. The low-pass filters may also be configured in a "secondary side control" configuration.

[0238] *Voltage sensor unit SEv* The voltage sensor unit SEv of the seventh zero-phase output configuration is the same as the voltage sensor unit SEv of the fifth zero-phase output configuration, and therefore a description thereof will be omitted.

[0239] *Current Sensor Unit SEi* A U-phase current sensor SEiu is provided in the wiring between the output terminal of the U-phase inverter unit INVu and the low-pass filter Flu to detect the internal U-phase current Iiu. A V-phase current sensor SEiv is provided in the wiring between the output terminal of the V-phase inverter unit INVv and the low-pass filter Flv to detect the internal V-phase current Iiv. A W-phase current sensor SEiw is provided in the wiring between the output terminal of the W-phase inverter unit INVw and the low-pass filter Flw to detect the internal W-phase current Iiw. The U-phase current sensor SEiu, V-phase current sensor SEiv, and W-phase current sensor SEiw constitute a current sensor unit SEi that detects the internal zero-sequence-containing unbalanced three-phase current Iubi. Note that the current sensor unit SEi may also be configured to detect the external zero-sequence-containing unbalanced three-phase current Iubo.

[0240] <Action and effect> According to this seventh zero-phase output configuration, the Y-connected U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw as well as the positive DC power supply section DCp and negative DC power supply section DCn are Y / Y-connected with the U-phase transformer, V-phase transformer, and W-phase transformer of the Y-connected three-phase transformer unit. Therefore, the internal zero-phase-containing unbalanced three-phase current Iubi output from the U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw of the three-phase four-wire inverter is input to the primary windings Wuf to Wwf of the U-phase transformer, V-phase transformer, and W-phase transformer of the three-phase transformer unit, and the zero-phase component current of the internal zero-phase-containing unbalanced three-phase current Iubi flows in a current path between the primary winding neutral point Nf and the power supply neutral point Ndc. Furthermore, because the secondary windings Wus-Wws of the U-phase transformer, V-phase transformer, and W-phase transformer of the three-phase transformer unit are Y-connected, the external zero-phase-containing unbalanced three-phase current Iubo, which is obtained by converting the internal zero-phase-containing unbalanced three-phase current Iubi in accordance with the turns ratio, is output by the Y-connected secondary windings Wus-Wws and secondary winding neutral point Ns of the U-phase transformer, V-phase transformer, and W-phase transformer. As a result, it is possible to suitably configure a combination of a DC power supply DC, a three-phase inverter device INV, and a three-phase transformer device T that is capable of outputting the zero-phase component of the external zero-phase-containing unbalanced three-phase current Iubo.

[0241] ≪8th zero phase output configuration≫ Fig. 17 is a circuit diagram showing details of the main circuit 2B including the eighth zero-phase output configuration in Fig. 13. Hereinafter, the contents of the main circuit 2B including the eighth zero-phase output configuration will be described with reference to Fig. 17.

[0242] <DC power supply DC> The direct current power supply DC of the eighth zero-phase output configuration is the same as the direct current power supply DC of the seventh zero-phase output configuration, and therefore a description thereof will be omitted.

[0243] <Three-phase inverter INV> The three-phase inverter device INV of the eighth zero-phase output configuration is the same as the three-phase inverter device INV of the seventh zero-phase output configuration, and therefore a description thereof will be omitted.

[0244] <Three-phase transformer T> Since the three-phase transformer T with the 8th zero-phase output configuration is similar to the three-phase transformer T with the 6th zero-phase output configuration, only the differences between the three-phase transformer T with the 8th zero-phase output configuration and the three-phase transformer T with the 6th zero-phase output configuration will be explained.

[0245] In the eighth zero-phase output configuration, the primary winding Wuf of the U-phase winding section Tu is connected to the output terminal of the U-phase inverter section INVu via a low-pass filter Flu. The primary winding Wvf of the V-phase winding section Tv is connected to the output terminal of the V-phase inverter section INVv via a low-pass filter Flv. The primary winding Wwf of the W-phase winding section Tw is connected to the output terminal of the W-phase inverter section INVw via a low-pass filter Flw.

[0246] The primary winding Wuf of the U-phase winding section Tu, the primary winding Wvf of the V-phase winding section Tv, and the primary winding Wwf of the W-phase winding section Tw of the three-phase five-legged core transformer are Y-connected at the primary winding neutral point Nf. The primary winding neutral point Nf is connected to the power supply neutral point Ndc, for example, by a neutral wire Wn. Note that the primary winding neutral point Nf and the power supply neutral point Ndc may be grounded, thereby connecting the primary winding neutral point Nf to the power supply neutral point Ndc. As a result, the U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw of the three-phase four-wire inverter are Y-connected at the power supply neutral point Ndc via a common positive DC power supply section DCp and negative DC power supply section DCn, and the Y-connected U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw and positive DC power supply section DCp and negative DC power supply section DCn are Y / Y-connected with the U-phase winding section Tu, V-phase winding section Tv, and W-phase winding section Tw of the Y-connected three-phase five-legged core transformer.

[0247] The secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, and the secondary winding Wws of the W-phase winding section Tw are star-connected at the secondary winding neutral point Ns.

[0248] In a three-phase five-legged core transformer, the internal U-phase current Iiu, internal V-phase current Iiv, and internal W-phase current Iiw of the internal zero-phase-sequence-containing unbalanced three-phase current Iubi from the three-phase four-wire inverter are input to the primary winding Wuf of the U-phase winding section Tu, the primary winding Wvf of the V-phase winding section Tv, and the primary winding Wwf of the W-phase winding section Tw, respectively. The internal U-phase current Iiu, internal V-phase current Iiv, and internal W-phase current Iiw are converted according to a predetermined turns ratio in the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, and the secondary winding Wws of the W-phase winding section Tw to generate an external zero-phase-sequence-containing unbalanced three-phase current Iubo including an external U-phase current Iou, an external V-phase current Iov, and an external W-phase current Iow. This external zero-phase-sequence-containing unbalanced three-phase current Iubo is output by the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, the secondary winding Wws of the W-phase winding section Tw, and the secondary winding neutral point Ns, which are all connected in a Y-connection of a three-phase five-legged core transformer.

[0249] <Elements other than the 8th zero-phase output configuration> *Low pass filter* Here, the low-pass filters are configured in a "primary side control" configuration. A U-phase low-pass filter Flu is arranged between the primary winding Wuf of the U-phase winding section Tu and the output terminal of the U-phase inverter section INVu. A V-phase low-pass filter Flv is arranged between the primary winding Wvf of the V-phase winding section Tv transformer and the output terminal of the V-phase inverter section INVv. A W-phase low-pass filter Flw is arranged between the primary winding Wwf of the W-phase winding section Tw and the output terminal of the W-phase inverter section INVw. The low-pass filters may also be configured in a "secondary side control" configuration.

[0250] *Voltage sensor unit SEv* The voltage sensor unit SEv of the eighth zero-phase output configuration is the same as the voltage sensor unit SEv of the sixth zero-phase output configuration, and therefore a description thereof will be omitted.

[0251] *Current Sensor Unit SEi* The current sensor unit SEi of the eighth zero-phase output configuration is the same as the current sensor unit SEi of the seventh zero-phase output configuration, and therefore a description thereof will be omitted.

[0252] <Action and effect> According to this eighth zero-phase output configuration, the Y-connected U-phase inverter unit INVu, V-phase inverter unit INVv, and W-phase inverter unit INVw as well as the positive DC power supply unit DCp and negative DC power supply unit DCn are Y / Y connected to the Y-connected U-phase winding unit Tu, V-phase winding unit Tv, and W-phase winding unit Tw of the three-phase five-leg core transformer. Therefore, the internal zero-phase-containing unbalanced three-phase current Iubi output from the U-phase inverter unit INVu, V-phase inverter unit INVv, and W-phase inverter unit INVw of the three-phase four-wire inverter is input to the primary windings Wuf to Wwf of the U-phase winding unit Tu, V-phase winding unit Tv, and W-phase winding unit Tw of the three-phase five-leg core transformer, and the zero-phase component current of the internal zero-phase-containing unbalanced three-phase current Iubi flows through a current path between the primary winding neutral point Nf and the power supply neutral point Ndc. Furthermore, the secondary windings Wus-Wws of the U-phase winding section Tu, V-phase winding section Tv, and W-phase winding section Tw are Y-connected. Therefore, the internal zero-phase-containing unbalanced three-phase current Iubi is converted in accordance with the turns ratio to generate an external zero-phase-containing unbalanced three-phase current Iubo, which is output from the Y-connected secondary windings Wus-Wws and secondary winding neutral point Ns of the U-phase winding section Tu, V-phase winding section Tv, and W-phase winding section Tw. In this case, the zero-phase magnetic flux passes through a pair of magnetic leakage legs. As a result, a suitable combination of a DC power supply DC, a three-phase inverter device INV, and a three-phase transformer device T can be constructed that can output the zero-phase component of the external zero-phase-containing unbalanced three-phase current Iubo.

[0253] {Control circuit 1B} Fig. 18 is a circuit diagram showing an example of the configuration of the control circuit 1B of Fig. 13. Referring to Fig. 18, the control circuit 1B is configured to perform feedback control of the internal zero-phase-sequence-containing unbalanced three-phase current Iubi. Note that the control circuit 1B may also be configured to perform feedforward control.

[0254] Specifically, the control circuit 1B includes a current command generating section 6, a current feedback control section 8, and a pulse modulation signal generating circuit 7. These elements will be described in detail below in order.

[0255] <Current command generation unit 6> The current command generating unit 6 includes a phase command value generating unit 61, a three-phase sine wave generating unit 62, a three-phase cosine wave generating unit 63, a sine wave amplitude determining unit 64, a cosine wave amplitude determining unit 65, and a current command amplitude determining unit 66.

[0256] The phase command value generating unit 61 receives a U-phase phase command value Cphu, a V-phase phase command value Cphv, and a W-phase phase command value Cphw of a predetermined zero-phase-containing unbalanced three-phase current from the higher-level controller 10. The phase command value generating unit 61 also receives phase information IFrphu of a U-phase reference internal sine wave, phase information IFrphv of a V-phase reference internal sine wave, and phase information IFrphw of a W-phase reference internal sine wave generated by a reference internal three-phase sine wave generating unit of the unbalanced three-phase power supply device 200.

[0257] The reference internal three-phase sine wave generator generates a reference internal sine wave for each phase based on the internal zero-phase-sequence-containing unbalanced three-phase voltage Vubi detected by the voltage sensor unit SEv, and extracts the phase of the reference internal sine wave for each phase. These processes can be performed by a well-known method using a PLL, so a description thereof will be omitted.

[0258] The phase command value generation unit 61 adds the U-phase phase command value Cphu, the V-phase phase command value Cphv, and the W-phase phase command value Cphw to the phase information IFrphu of the U-phase reference internal sine wave, the phase information IFrphv of the V-phase reference internal sine wave, and the phase information IFrphw of the W-phase reference internal sine wave, respectively, using a U-phase adder 611, a V-phase adder 612, and a W-phase adder 613, and outputs the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value obtained by this addition. At this time, the phase command value generation unit 61 outputs the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value at a predetermined timing, that is, when a predetermined time has elapsed from a predetermined reference time.

[0259] The three-phase sine wave generating unit 62 includes a U-phase sine table 621, a V-phase sine table 622, and a W-phase sine table 623. The sine table is a table (graph) that indicates the relationship (function) in which the frequency of a sine wave is proportional to time in a two-axis orthogonal coordinate system, one axis of which represents the elapsed time from the predetermined reference time and the other axis of which represents the frequency of the sine wave.

[0260] When the three-phase sine wave generator 62 receives the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value from the phase command value generator 61, the three-phase sine wave generator 62 identifies the timing of each input, i.e., the elapsed time from the predetermined reference time until the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value are input, and compares the identified input timing of the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value with a U-phase sin table 621, a V-phase sin table 622, and a W-phase sin table 623. The three-phase sine wave generator 62 determines the frequencies corresponding to the input timing of the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value in the U-phase sin table 621, the V-phase sin table 622, and the W-phase sin table 623 as the frequency of the U-phase sine wave, the V-phase sine wave, and the W-phase sine wave, respectively. Furthermore, the three-phase sine wave generator 62 determines the phases indicated by the U-phase phase command value, V-phase phase command value, and W-phase phase command value to be the phases of the U-phase sine wave, V-phase sine wave, and W-phase sine wave, respectively. In this way, the three-phase sine wave generator 62 generates U-phase sine waves, V-phase sine waves, and W-phase sine waves having frequencies, phases, and reference amplitudes corresponding to the U-phase phase command value, V-phase phase command value, and W-phase phase command value, respectively.

[0261] The three-phase cosine wave generator 63 includes a U-phase cosine table 631, a V-phase cosine table 632, and a W-phase cosine table 633. The cosine table is a table (graph) showing a relationship (function) in which the frequency of a cosine wave is proportional to time in a two-axis Cartesian coordinate system, where one axis represents the elapsed time from the predetermined reference time and the other axis represents the frequency of the cosine wave (cosine wave). When the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value are input from the phase command value generator 61, the three-phase cosine wave generator 63 determines the input timing of each value, i.e., the elapsed time from the predetermined reference time until the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value are input, and compares the determined input timing of the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value with the U-phase cosine table 631, the V-phase cosine table 632, and the W-phase cosine table 633, respectively. Three-phase cosine wave generator 63 determines the frequencies corresponding to the input timing of the U-phase phase command value, the input timing of the V-phase phase command value, and the input timing of the W-phase phase command value as the frequencies of the U-phase cosine wave, the V-phase cosine wave, and the W-phase cosine wave, respectively, in U-phase cosine table 631, V-phase cosine table 632, and W-phase cosine table 633. Furthermore, three-phase cosine wave generator 63 determines the phases indicated by the U-phase phase command value, V-phase phase command value, and W-phase phase command value, respectively, as the phases of the U-phase cosine wave, the V-phase cosine wave, and the W-phase cosine wave. In this way, three-phase cosine wave generator 63 generates U-phase cosine waves, V-phase cosine waves, and W-phase cosine waves having frequencies, phases, and reference amplitudes corresponding to the U-phase phase command value, V-phase phase command value, and W-phase phase command value, respectively.

[0262] The sine wave amplitude determiner 64 receives a U-phase active component amplitude command value Camue, a V-phase active component amplitude command value Camve, and a W-phase active component amplitude command value Camwe of a predetermined zero-phase-containing unbalanced three-phase current from the upper controller 10. The sine wave amplitude determiner 64 determines the amplitudes of the U-phase sine wave, the V-phase sine wave, and the W-phase sine wave by multiplying the amplitude values of the U-phase sine wave, the V-phase sine wave, and the W-phase sine wave generated by the three-phase sine wave generator 62 by the U-phase, V-phase, and W-phase active component amplitude command values of the predetermined zero-phase-containing unbalanced three-phase current, respectively, thereby generating a U-phase sine wave command, a V-phase sine wave command, and a W-phase sine wave command.

[0263] The cosine wave amplitude determiner 65 receives a U-phase reactive component amplitude command value Camur, a V-phase reactive component amplitude command value Camvr, and a W-phase reactive component amplitude command value Camwr of a predetermined zero-phase-containing unbalanced three-phase current from the higher-level controller 10. The cosine wave amplitude determiner 65 determines the amplitudes of the U-phase cosine wave, the V-phase cosine wave, and the W-phase cosine wave by multiplying the amplitude values of the U-phase cosine wave, the V-phase cosine wave, and the W-phase cosine wave generated by the three-phase cosine wave generator 63 by the U-phase, V-phase, and W-phase reactive component amplitude command values of the predetermined zero-phase-containing unbalanced three-phase current, respectively, using a U-phase multiplier 651, a V-phase multiplier 652, and a W-phase multiplier 653. As a result, the cosine wave amplitude determiner 65 generates a U-phase reactive component current command, a V-phase reactive component current command, and a W-phase reactive component current command.

[0264] The current command amplitude determination unit 66 uses a U-phase adder 661, a V-phase adder 662, and a W-phase adder 663 to add the U-phase reactive current command, the V-phase reactive current command, and the W-phase reactive current command values to the U-phase active current command, the V-phase active current command, and the W-phase active current command, respectively, thereby generating a U-phase current command Ciu, a V-phase current command Civ, and a W-phase current command Ciw.

[0265] <Current feedback control unit 8> The current feedback control unit 8 includes a current error generating unit 81 and a current compensating unit 82.

[0266] The internal U-phase current Iiu, internal V-phase current Iiv, and internal W-phase current Iiw of the internal zero-sequence-containing unbalanced three-phase current Iubi detected by the current sensor unit SEi are input to the current error generator 81. Using a U-phase subtractor 811, a V-phase subtractor 812, and a W-phase subtractor 813, the current error generator 81 generates a U-phase current error, a V-phase current error, and a W-phase current error, which are errors between the internal U-phase current Iiu, the internal V-phase current Iiv, and the internal W-phase current Iiw of the internal zero-sequence-containing unbalanced three-phase current Iubi and the U-phase current command Ciu, the V-phase current command Civ, and the W-phase current command Ciw generated by the current command amplitude determiner 66. When current sensor unit SEi detects external zero-sequence-containing unbalanced three-phase current Iubo, the external U-phase current Iou, the external V-phase current Iov, and the external W-phase current Iow of the external zero-sequence-containing unbalanced three-phase current Iubo detected by current sensor unit SEi are input to current error generator 81. Using a U-phase subtractor 811, a V-phase subtractor 812, and a W-phase subtractor 813, current error generator 81 generates a U-phase current error, a V-phase current error, and a W-phase current error, which are errors between the external U-phase current Iou, the external V-phase current Iov, and the external W-phase current Iow of the external zero-sequence-containing unbalanced three-phase current Iubo and the U-phase current command Ciu, the V-phase current command Civ, and the W-phase current command Ciw generated by current command amplitude determiner 66.

[0267] The current compensation unit 82 generates a U-phase current control input Oiu, a V-phase current control input Oiv, and a W-phase current control input Oiw by applying compensation to the U-phase current error, V-phase current error, and W-phase current error generated by the current error generation unit 81 using a U-phase compensation unit 821, a V-phase compensation unit 823, and a W-phase compensation unit 824.

[0268] <Pulse modulation signal generation circuit 7> The pulse modulated signal generating circuit 7 includes a U-phase comparator 71, a U-phase inverting element 72, a V-phase comparator 73, a V-phase inverting element 74, a W-phase comparator 75, and a W-phase inverting element .

[0269] The U-phase comparator 71 receives the U-phase current control variable Oiu generated by the current compensation unit 82 at its non-inverting input terminal and receives the triangular wave carrier signal Vcu at its inverting input terminal. The U-phase comparator 71 compares the U-phase current control variable Oiu with the triangular wave carrier signal Vcu to generate a U-phase positive-phase pulse modulated signal Spup, which is a PWM signal corresponding to the U-phase current control variable Oiu. The U-phase inverting element 72 inverts the U-phase positive-phase pulse modulated signal Spup to generate a U-phase negative-phase pulse modulated signal Spuo. The U-phase positive-phase pulse modulated signal Spup and the U-phase negative-phase pulse modulated signal Spuo constitute the U-phase pulse modulated signal Spu.

[0270] The V-phase comparator 73 receives the V-phase current control variable Oiv generated by the current compensation unit 82 at its non-inverting input terminal and receives the triangular wave carrier signal Vcv at its inverting input terminal. The V-phase comparator 73 compares the V-phase current control variable Oiv with the triangular wave carrier signal Vcv to generate a V-phase positive-phase pulse modulated signal Spvp, which is a PWM signal corresponding to the V-phase current control variable Oiv. The V-phase inverting element 74 inverts the V-phase positive-phase pulse modulated signal Spvp to generate a V-phase negative-phase pulse modulated signal Spvo. The V-phase positive-phase pulse modulated signal Spvp and the V-phase negative-phase pulse modulated signal Spvo constitute the V-phase pulse modulated signal Spv.

[0271] The W-phase comparator 75 receives the W-phase current control variable Oiw generated by the current compensation unit 82 at its non-inverting input terminal and the triangular wave carrier signal at its inverting input terminal. The W-phase comparator 75 compares the W-phase current control variable Oiw with the triangular wave carrier signal Vcw to generate a W-phase positive-phase pulse modulated signal Spwp, which is a PWM signal corresponding to the W-phase current control variable Oiw. The W-phase inverting element 76 inverts the W-phase positive-phase pulse modulated signal Spwp to generate a W-phase negative-phase pulse modulated signal Spwo. The W-phase positive-phase pulse modulated signal Spwp and the W-phase negative-phase pulse modulated signal Spwo constitute the W-phase pulse modulated signal Spw.

[0272] <Configuration of Current Command Generator 6 and Current Feedback Controller 8> The current command generating unit 6 and the current feedback control unit 8, except for the three-phase sine wave generating unit 62 and the three-phase cosine wave generating unit 63, can be configured by, for example, an electronic circuit using an operational amplifier.

[0273] The current command generating unit 6 and the current feedback control unit 8 can also be configured by software. In this case, for example, a computing unit having a processor and a memory is used, and a predetermined program for executing the functions of the current command generating unit 6 and the current feedback control unit 8 is stored in the memory of the computing unit. The predetermined program is read and executed by the processor, thereby realizing the current command generating unit 6 and the current feedback control unit 8 as functional blocks. In this case, the computing unit operates as the current command generating unit 6 and the current feedback control unit 8. This computing unit can be configured by, for example, a computer, a personal computer, a microcontroller, an MPU, an FPGA (Field Programmable Gate Array), a PLC (Programmable Logic Controller), or the like.

[0274] It should be noted that the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this disclosure, a "circuit" or "unit" is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where hardware is a processor, which is considered a type of circuit, the "circuit" or "unit" is a combination of hardware and software, and software is used to configure the hardware and / or processor.

[0275] <Host controller 10> The upper controller 10 is not particularly limited as long as it can output a U-phase phase command value Cphu, a V-phase phase command value Cphv, and a W-phase phase command value Cphw of a predetermined zero-phase-containing unbalanced three-phase current, as well as a U-phase active component amplitude command value Camue, a V-phase active component amplitude command value Camve, a W-phase active component amplitude command value Camwe, a U-phase reactive component amplitude command value Camur, a V-phase reactive component amplitude command value Camvr, and a W-phase reactive component amplitude command value Camwr. The upper controller 10 is configured, for example, with a computer, a personal computer, a microcontroller, an MPU, an FPGA, a PLC, or the like. Communication between the upper controller 10 and the current command generating unit 6 is performed, for example, via a wired or wireless connection or a data communication network. The upper controller 10 may be located either outside or inside the unbalanced three-phase power supply device 200.

[0276] <Operation> The operation of the unbalanced three-phase power supply device 200 configured as above will be described with reference to Figures 13 to 18. In the following, a case where the control circuit 1B includes a current feedback control unit 8 will be described.

[0277] 13 and 18, the current command generating unit 6 receives from the higher-level controller 10 a U-phase phase command value Cphu, a V-phase phase command value Cphv, and a W-phase phase command value Cphw of a predetermined zero-phase-containing unbalanced three-phase current, as well as a U-phase active component amplitude command value Camue, a V-phase active component amplitude command value Camve, a W-phase active component amplitude command value Camwe, a U-phase reactive component amplitude command value Camur, a V-phase reactive component amplitude command value Camvr, and a W-phase reactive component amplitude command value Camwr. The current command generating unit 6 generates a U-phase current command Ciu, a V-phase current command Civ, and a W-phase current command Ciw having phases, frequencies, and amplitudes corresponding to the U-phase phase command value Cphu, the V-phase phase command value Cphv, and the W-phase phase command value Cphw of the received predetermined zero-phase-containing unbalanced three-phase current, and the U-phase active component amplitude command value Camue, the V-phase active component amplitude command value Camve, the W-phase active component amplitude command value Camwe, the U-phase reactive component amplitude command value Camur, the V-phase reactive component amplitude command value Camvr, and the W-phase reactive component amplitude command value Camwr, respectively.

[0278] The current feedback control unit 8 generates a U-phase current control variable Oiu, a V-phase current control variable Oiv, and a W-phase current control variable Oiw based on errors of the internal U-phase current Iiu, the internal V-phase current Iiv, and the internal W-phase current Iiw of the internal zero-sequence-containing unbalanced three-phase current Iubi relative to the U-phase current command Ciu, the V-phase current command Civ, and the W-phase current command Ciw from the current command generation unit 6. When the current sensor unit SEi detects the external zero-sequence-containing unbalanced three-phase current Iubo, the current feedback control unit 8 generates the U-phase current control variable Oiu, the V-phase current control variable Oiv, and the W-phase current control variable Oiw based on errors of the external U-phase current Iou, the external V-phase current Iov, and the external W-phase current Iow of the external zero-sequence-containing unbalanced three-phase current Iubo relative to the U-phase current command Ciu, the V-phase current command Civ, and the W-phase current command Ciw generated by the current command amplitude determination unit 66.

[0279] The pulse modulation signal generation circuit 7 outputs a U-phase pulse modulation signal Spu, a V-phase pulse modulation signal Spv, and a W-phase pulse modulation signal Spw, which correspond to the U-phase current control input Oiu, the V-phase current control input Oiv, and the W-phase current control input Oiw, which are generated by the current feedback control unit 8.

[0280] 13 and 14 to 17, the U-phase inverter section INVu, V-phase inverter section INVv, and W-phase inverter section INVw of the three-phase inverter device INV use a predetermined DC voltage or DC current from the DC power supply DC in accordance with a U-phase pulse modulation signal Spu, a V-phase pulse modulation signal Spv, and a W-phase pulse modulation signal Spw from the pulse modulation signal generation circuit 7, to generate a U-phase phase command value Cphu, a V-phase phase command value Cphv, and a W-phase phase command value Cphw, and The internal circuit generates an internal U-phase current Iiu, an internal V-phase current Iiv, and an internal W-phase current Iiw having phases, frequencies, and amplitudes corresponding to the U-phase active component amplitude command value Camue, the V-phase active component amplitude command value Camve, the W-phase active component amplitude command value Camwe, the U-phase reactive component amplitude command value Camur, the V-phase reactive component amplitude command value Camvr, and the W-phase reactive component amplitude command value Camwr, respectively, thereby outputting an internal zero-sequence-containing unbalanced three-phase current Iubi including the internal U-phase current Iiu, the internal V-phase current Iiv, and the internal W-phase current Iiw.

[0281] In the three-phase transformer T, the internal U-phase current Iiu, the internal V-phase current Iiv, and the internal W-phase current Iiw of the internal zero-phase-containing unbalanced three-phase current Iubi from the three-phase inverter INV are input to the primary winding Wuf of the U-phase winding section Tu, the primary winding Wvf of the V-phase winding section Tv, and the primary winding Wwf of the W-phase winding section Tw, respectively.

[0282] Here, the DC power supply DC of the main circuit 2B, the three-phase inverter device INV, and the three-phase transformer device T have respective configurations and mutual connection relationships that enable them to output the zero-phase component of the external zero-phase-containing unbalanced three-phase current Iubo, which is obtained by converting the internal zero-phase-containing unbalanced three-phase current Iubi in the three-phase transformer device T in accordance with the turns ratio, so that the external zero-phase-containing unbalanced three-phase current Iubo is output from the secondary winding Wus of the U-phase winding section Tu, the secondary winding Wvs of the V-phase winding section Tv, the secondary winding Wws of the W-phase winding section Tw, and the secondary winding neutral point Ns, which are Y-connected in the three-phase transformer device T. In addition, the internal zero-phase-containing unbalanced three-phase current Iubi is feedback-controlled by a current feedback control unit 8.

[0283] 13 and 18, according to the unbalanced three-phase power supply device 200, the phase command values Cphue, Cphur, Cphve, Cphvr, Cphwe, Cphwr and amplitude command values Camue, Camur, Camve, Camvr, Camwe, Camwr of the U-phase, V-phase, and W-phase of the received predetermined zero-phase-containing unbalanced three-phase current are processed independently for each of the U-phase, V-phase, and W-phase in the unbalanced three-phase power supply device 200, so that the external zero-phase-containing unbalanced three-phase current Iubo corresponding to the predetermined zero-phase-containing unbalanced three-phase current can be generated. Furthermore, the DC power supply DC, the three-phase inverter INV, and the three-phase transformer T have respective configurations and mutual connection relationships that enable them to output the zero-phase component of the generated external zero-phase-containing unbalanced three-phase current Iubo, so that the zero-phase component of the external zero-phase-containing unbalanced three-phase current Iubo can be output. Therefore, it is possible to provide an unbalanced three-phase power supply device 200 that can output a desired unbalanced three-phase current Iubo containing a zero-sequence component by setting a desired zero-sequence-containing three-phase unbalanced voltage to a predetermined zero-sequence-containing unbalanced three-phase current. Because the unbalanced three-phase power supply device 200 generates the unbalanced three-phase current Iubo containing a zero-sequence component using the three-phase inverter device INV, use of the unbalanced three-phase power supply device 200 makes it easy to create a test environment that uses the unbalanced three-phase current Iubo containing a zero-sequence component.

[0284] [simulation] In order to confirm the operational effects of the unbalanced three-phase power supply device 200 of the third embodiment, a simulation of the operation of the unbalanced three-phase power supply device 200 was performed. This simulation was performed on a main circuit 2B including the fifth to eighth zero-phase output configurations when the current sensor unit SEi detects the internal zero-phase-containing unbalanced three-phase current Iubi. These simulation results confirmed that the unbalanced three-phase power supply device 200 of the third embodiment exhibits the operational effects of the present disclosure. Note that the results of these simulations are similar to those of the first embodiment, and therefore a description thereof will be omitted.

[0285] (Embodiment 4) A fourth embodiment of the present disclosure illustrates an evaluation power supply including the unbalanced three-phase power supply device 200 of the third embodiment. Fig. 19 is a functional block diagram showing an example of the configuration of an evaluation power supply 2000 according to the fourth embodiment of the present disclosure.

[0286] 19, a power supply 2000 for evaluation includes an input-side three-phase transformer 20 and an unbalanced three-phase power supply 200 of the third embodiment. The input terminal of the input-side three-phase transformer 20 is connected to, for example, a power grid 21. In the unbalanced three-phase power supply 200, a direct-current power supply DC is configured with a converter circuit that converts the three-phase current of the power grid input via the input-side three-phase transformer 20 into a direct-current voltage or a direct-current. This converter circuit corresponds to the capacitor of the direct-current power supply DC and the DC power supply in the preceding stage of the direct-current power supply DC of the third embodiment. In addition, a device under evaluation 22 is connected to output terminals U, V, W, and n (see FIGS. 14 to 17) on the secondary side of the three-phase transformer T.

[0287] According to this evaluation power supply 2000, the unbalanced three-phase power supply device 200 uses system power from the power grid 21 to supply an external zero-sequence-containing unbalanced three-phase current Iubo corresponding to an unbalanced three-phase current containing a predetermined zero-sequence component to the device under evaluation 22. Therefore, it is possible to evaluate the response performance of the device under evaluation 22 to an unbalanced three-phase current containing a zero-sequence component in a test environment that can be easily constructed.

[0288] (Other embodiments) In the first embodiment, the main circuit 2A may be configured as a zero-phase output configuration other than the first to fourth zero-phase output configurations, and the direct current power supply DC, the three-phase inverter device INV, and the three-phase transformer device T may be configured as a zero-phase output configuration having respective forms and mutual connection relationships that enable them to output the zero-phase component (external zero-phase voltage Vo0) of the external zero-phase-containing unbalanced three-phase voltage Vubo obtained by converting the internal zero-phase-containing unbalanced three-phase voltage Vubi in the three-phase transformer device T according to the turns ratio.

[0289] In the third embodiment, the main circuit 2B may have a zero-phase output configuration other than the fifth to eighth zero-phase output configurations, and the direct current power supply DC, the three-phase inverter INV, and the three-phase transformer T may be configured to have respective forms and mutual connection relationships that enable them to output the zero-phase component of the external zero-phase-containing unbalanced three-phase current Iubo obtained by converting the internal zero-phase-containing unbalanced three-phase current Iubi in the three-phase transformer T according to the turns ratio.

[0290] In the first or second embodiment, the pulse modulation signal generating circuit 4 may be configured as a circuit that generates a pulse modulation signal other than a PWM signal.

[0291] In the third or fourth embodiment, the pulse modulation signal generating circuit 7 may be configured as a circuit that generates a pulse modulation signal other than a PWM signal.

[0292] Many modifications and alternative embodiments will be apparent to those skilled in the art in light of the above description, and therefore the above description should be construed as illustrative only. [Industrial Applicability]

[0293] The unbalanced three-phase power supply device of the present disclosure is useful as a power supply device that can easily create a test environment using an unbalanced three-phase voltage or an unbalanced three-phase current that includes a zero-phase component. [Explanation of symbols]

[0294] 1A, 1B control circuit 2A,2B main circuit 3. Voltage command generator 4 Pulse modulation signal generation circuit 5. Voltage feedback control circuit 6 Current command generation section 7 Pulse modulation signal generation circuit 8 Current feedback control section 10 Upper controller 20 Input transformer 21 Power system 22 Evaluated device 31 Phase command value generator 32 Three-phase sine wave generator 33 Voltage command generator 51 Voltage error generator 52 Voltage compensation section 61 Phase command value generator 62 Three-phase sine wave generator 63 Three-phase cosine wave generator 64 Sine wave amplitude determination unit 65 Cosine wave amplitude determination section 66 Current command amplitude determination section 81 Current error generation section 82 Current compensation section 100, 200 unbalanced three-phase power supply Camu U-phase amplitude command value Camue U phase active amplitude command value Camur U-phase reactive amplitude command value Camv V-phase amplitude command value Camue V-phase active amplitude command value Camur V-phase reactive amplitude command value Camw W-phase amplitude command value Camwe W-phase active amplitude command value Camwr W-phase reactive amplitude command value Ciu U phase current command Civ V-phase current command Ciw W phase current command Cphu U phase phase command value Cphue U-phase active phase command value Cphur U-phase reactive phase command value Cphv V phase phase command value Cphve V-phase active phase command value Cphvr V-phase reactive phase command value Cphw W phase phase command value Cphwe W-phase active phase command value Cphwr W-phase reactive phase command value Cv0 Zero phase component Cvu U phase voltage command Cvv V-phase voltage command Cvw W-phase voltage command DC DC power supply DCn Negative DC power supply section DCp Positive DC power supply section DCu U-phase DC power supply section DCv V-phase DC power supply section DCw W-phase DC power supply section Flu, Flv, Flw low pass filter IFubi unbalanced three-phase current information IFubv Unbalanced three-phase voltage information INV Three-phase inverter device INVu U-phase inverter INVv V-phase inverter INVw W-phase inverter Iiu Internal U phase current Iiv Internal V phase current Iiw Internal W phase current Iou Outer U phase current Iov External V-phase current Iow External W-phase current Iubi Unbalanced three-phase current containing internal zero-phase Iubo Unbalanced three-phase current including external zero phase Ndc power neutral point Nf Primary winding neutral point Ns Secondary winding neutral point Oiu U phase current manipulated variable Oiv V-phase current manipulated variable Oiw W phase current manipulated variable Ovu U phase voltage control amount Ovv V-phase voltage control amount Ovw W-phase voltage control amount Q1u~Q4w switching elements SEi Current Sensor Unit SEv Current Sensor Unit Spu U-phase pulse modulation signal Spv V-phase pulse modulation signal Spw W-phase pulse modulation signal T Three-phase transformer Tu U phase winding section TV V phase winding section Tw W-phase winding Viu Internal U phase voltage Viv Internal V phase voltage Viw Internal W phase voltage Vou External U phase voltage Vov External V phase voltage Vow External W phase voltage

Claims

1. A control circuit includes: a voltage command generation unit that receives unbalanced three-phase voltage information including phase command values ​​and amplitude command values ​​for the U-phase, V-phase, and W-phase of a zero-sequence-containing unbalanced three-phase voltage which is an unbalanced three-phase voltage containing a predetermined zero-sequence component, and generates U-phase voltage commands, V-phase voltage commands, and W-phase voltage commands having phase, frequency, and amplitude corresponding to the phase command values ​​and amplitude command values ​​of the U-phase, V-phase, and W-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage, respectively, based on the unbalanced three-phase voltage information; and a pulse modulation signal generation circuit that outputs U-phase pulse modulation signals, V-phase pulse modulation signals, and W-phase pulse modulation signals corresponding to the U-phase voltage commands, V-phase voltage commands, and W-phase voltage commands generated by the voltage command generation unit; The system comprises a DC power supply that outputs a predetermined DC voltage, a U-phase inverter section, a V-phase inverter section, and a W-phase inverter section, and the U-phase inverter section, the V-phase inverter section, and the W-phase inverter section each generate U-phase voltage, V-phase voltage, and W-phase voltage from the predetermined DC voltage from the DC power supply according to the U-phase pulse modulation signal, V-phase pulse modulation signal, and W-phase pulse modulation signal from the pulse modulation signal generation circuit, respectively, having phase, frequency, and amplitude corresponding to the phase command values ​​and amplitude command values ​​of the U-phase, V-phase, and W-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage, thereby generating the U-phase voltage, the V-phase voltage, and the W-phase voltage. A three-phase inverter device that outputs a voltage and an internal zero-sequence-containing unbalanced three-phase voltage including the W-phase voltage; and a three-phase transformer having a U-phase winding section, a V-phase winding section, a W-phase winding section, and a secondary winding neutral point, wherein the secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, and the secondary winding of the W-phase winding section are connected in a Y configuration, the secondary winding neutral point is the neutral point of the Y configuration, and the U-phase voltage, V-phase voltage, and W-phase voltage of the internal zero-sequence-containing unbalanced three-phase voltage from the three-phase inverter device are input to the primary winding of the U-phase winding section, the primary winding of the V-phase winding section, and the primary winding of the W-phase winding section, respectively; and a main circuit including a three-phase transformer. An unbalanced three-phase power supply device in which the DC power supply of the main circuit, the three-phase inverter device, and the three-phase transformer device have respective configurations and interconnections that enable the output of the zero-sequence component of the external zero-sequence unbalanced three-phase voltage obtained by converting the internal zero-sequence unbalanced three-phase voltage in the three-phase transformer according to the turns ratio, and the external zero-sequence unbalanced three-phase voltage is output by the secondary winding of the U-phase winding section, the V-phase winding section, the W-phase winding section, and the neutral point of the secondary winding of the three-phase transformer, which is connected in a Y configuration.

2. The main circuit includes a voltage sensor unit that detects the U-phase, V-phase, and W-phase voltages of the internal zero-sequence-containing unbalanced three-phase voltage or the external zero-sequence-containing unbalanced three-phase voltage. The control circuit further comprises a voltage feedback control unit, The voltage command generation unit, A phase command value generation unit adds the phase command values ​​of the U-phase, V-phase, and W-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage to the respective phases of the U-phase, V-phase, and W-phase of the reference internal three-phase sine wave, and outputs the U-phase phase command value, V-phase phase command value, and W-phase phase command value obtained by the addition. A three-phase sine wave generation unit compares the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value and their respective input timings generated by the phase command value generation unit with a sin table, and generates U-phase sine waves, V-phase sine waves, and W-phase sine waves having phases, frequencies, and reference amplitudes corresponding to the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value, respectively. The system includes a voltage command amplitude determination unit that determines the amplitude of the U-phase sine wave, the V-phase sine wave, and the W-phase sine wave by multiplying the amplitude values ​​of the U-phase, V-phase, and W-phase sine waves generated by the three-phase sine wave generation unit by the respective amplitude command values ​​of the U-phase, V-phase, and W-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage, thereby generating the U-phase voltage command, the V-phase voltage command, and the W-phase voltage command, respectively. The voltage feedback control unit, A voltage error generation unit generates U-phase voltage error, V-phase voltage error, and W-phase voltage error, which are voltage errors in the U-phase, V-phase, and W-phase of the internal zero-sequence-containing unbalanced three-phase voltage or the external zero-sequence-containing unbalanced three-phase voltage detected by the voltage sensor unit for the U-phase voltage command, V-phase voltage command, and W-phase voltage command generated by the voltage command amplitude determination unit, The system includes a voltage compensation unit that generates a U-phase voltage manipulation amount, a V-phase voltage manipulation amount, and a W-phase voltage manipulation amount by applying compensation to the U-phase voltage error, the V-phase voltage error, and the W-phase voltage error generated by the voltage error generation unit, respectively. The unbalanced three-phase power supply according to claim 1, wherein the pulse modulation signal generation circuit is a circuit that generates the U-phase pulse modulation signal, the V-phase pulse modulation signal, and the W-phase pulse modulation signal, respectively, corresponding to the U-phase voltage manipulation amount, the V-phase voltage manipulation amount, and the W-phase voltage manipulation amount generated by the voltage compensation unit.

3. The DC power supply comprises a U-phase DC power supply unit, a V-phase DC power supply unit, and a W-phase DC power supply unit, each outputting the predetermined DC voltage. The three-phase inverter device comprises a U-phase inverter section comprising a single-phase U-phase inverter that generates an internal U-phase voltage having phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the U-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage from a predetermined DC voltage from the U-phase DC power supply section according to the U-phase pulse modulation signal from the pulse modulation signal generation circuit, and a V-phase inverter section comprising a single-phase U-phase inverter that generates an internal V-phase voltage having phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the V-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage from a predetermined DC voltage from the V-phase DC power supply section according to the V-phase pulse modulation signal from the pulse modulation signal generation circuit. A three-phase inverter unit comprising: a V-phase inverter; a single-phase W-phase inverter that constitutes the W-phase inverter section and generates an internal W-phase voltage having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the W-phase of a predetermined zero-sequence-containing unbalanced three-phase voltage from the predetermined DC voltage from the W-phase DC power supply section according to the W-phase pulse modulation signal from the pulse modulation signal generation circuit; and the U-phase inverter, the V-phase inverter, and the W-phase inverter output the internal zero-sequence-containing unbalanced three-phase voltage which includes the internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage as the U-phase voltage, the V-phase voltage, and the W-phase voltage, respectively. The three-phase transformer unit comprises a single-phase U-phase transformer constituting the U-phase winding section, a single-phase V-phase transformer constituting the V-phase winding section, and a single-phase W-phase transformer constituting the W-phase winding section, wherein the secondary windings of the U-phase transformer, the V-phase transformer, and the W-phase transformer are connected in a Y configuration, and the neutral point of the Y configuration is the neutral point of the secondary winding. The internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage from the three-phase inverter unit are input to the primary winding of the U-phase transformer, the primary winding of the V-phase transformer, and the primary winding of the W-phase transformer, respectively, and An unbalanced three-phase power supply device according to claim 1 or 2, wherein the internal zero-sequence-containing unbalanced three-phase voltage is converted according to the turns ratio to obtain an external zero-sequence-containing unbalanced three-phase voltage which is output by the secondary winding of the U-phase transformer, the V-phase transformer, the W-phase transformer, and the neutral point of the secondary winding, all of which are connected in a Y configuration in the three-phase transformer unit.

4. The DC power supply comprises a U-phase DC power supply unit, a V-phase DC power supply unit, and a W-phase DC power supply unit, each outputting the predetermined DC voltage. The three-phase inverter device comprises a U-phase inverter section comprising a single-phase U-phase inverter that generates an internal U-phase voltage having phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the U-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage from a predetermined DC voltage from the U-phase DC power supply section according to the U-phase pulse modulation signal from the pulse modulation signal generation circuit, and a V-phase inverter section comprising a single-phase U-phase inverter that generates an internal V-phase voltage having phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the V-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage from a predetermined DC voltage from the V-phase DC power supply section according to the V-phase pulse modulation signal from the pulse modulation signal generation circuit. A three-phase inverter unit comprising: a V-phase inverter; a single-phase W-phase inverter that constitutes the W-phase inverter section and generates an internal W-phase voltage having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the W-phase of a predetermined zero-sequence-containing unbalanced three-phase voltage from the predetermined DC voltage from the W-phase DC power supply section according to the W-phase pulse modulation signal from the pulse modulation signal generation circuit; and the U-phase inverter, the V-phase inverter, and the W-phase inverter output the internal zero-sequence-containing unbalanced three-phase voltage which includes the internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage as the U-phase voltage, the V-phase voltage, and the W-phase voltage, respectively. The three-phase transformer comprises a three-phase five-legged core having U-legs, V-legs, W-legs, and a pair of magnetic leakage legs, a U-phase winding section provided on the U-phase leg, a V-phase winding section provided on the V-phase leg, and a W-phase winding section provided on the W-phase leg, wherein the secondary windings of the U-phase winding section, the V-phase winding section, and the W-phase winding section are connected in a Y configuration, and the neutral point of the Y configuration is the neutral point of the secondary winding. The internal U-phase voltage, internal V-phase voltage, and internal W-phase voltage from the three-phase inverter unit are input to the primary winding of the U-phase winding section, the primary winding of the V-phase winding section, and the primary winding of the W-phase winding section of the three-phase five-legged core transformer, respectively, and An unbalanced three-phase power supply device according to claim 1 or 2, wherein the internal zero-sequence-containing unbalanced three-phase voltage is converted according to the turns ratio to obtain an external zero-sequence-containing unbalanced three-phase voltage which is output by the secondary winding of the U-phase winding section, the V-phase winding section, the W-phase winding section, and the neutral point of the secondary winding of the three-phase five-legged core transformer, which is connected in a Y configuration.

5. The DC power supply comprises a positive DC power supply unit and a negative DC power supply unit, which are connected in series with each other at the power supply neutral point and each outputs the predetermined DC voltage. The three-phase inverter device comprises: a U-phase inverter unit that generates an internal U-phase voltage having phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the U-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage from the predetermined DC voltages from the positive DC power supply unit and the negative DC power supply unit, in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit; a V-phase inverter unit that generates an internal V-phase voltage having phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the V-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage from the predetermined DC voltages from the positive DC power supply unit and the negative DC power supply unit, in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit; and the pulse modulation signal A three-phase four-wire inverter comprising: a W-phase inverter unit that generates an internal W-phase voltage having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the W-phase of a predetermined zero-sequence-containing unbalanced three-phase voltage from a predetermined DC voltage from a positive DC power supply unit and a negative DC power supply unit according to the W-phase pulse modulation signal from a generation circuit; the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit are connected between the positive electrode of the positive DC power supply unit and the negative electrode of the negative DC power supply unit, and outputs an internal zero-sequence-containing unbalanced three-phase voltage that includes the internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage as the U-phase voltage, the V-phase voltage, and the W-phase voltage, respectively; The three-phase transformer unit comprises a single-phase U-phase transformer constituting the U-phase winding section, a single-phase V-phase transformer constituting the V-phase winding section, and a single-phase W-phase transformer constituting the W-phase winding section, wherein one end of the primary winding of the U-phase transformer, one end of the primary winding of the V-phase transformer, and one end of the primary winding of the W-phase transformer are Y-connected at the primary winding neutral point, and the secondary winding of the U-phase transformer, the secondary winding of the V-phase transformer, and the secondary winding of the W-phase transformer are Y-connected at the secondary winding neutral point, and the primary winding neutral point is connected to the power supply neutral point of the DC power supply. The internal U-phase voltage, internal V-phase voltage, and internal W-phase voltage from the three-phase four-wire inverter are input to the other end of the primary winding of the U-phase transformer, the other end of the primary winding of the V-phase transformer, and the other end of the primary winding of the W-phase transformer, respectively, and An unbalanced three-phase power supply device according to claim 1 or 2, wherein the internal zero-sequence-containing unbalanced three-phase voltage is converted according to the turns ratio to obtain an external zero-sequence-containing unbalanced three-phase voltage which is output by the secondary winding of the U-phase transformer, the V-phase transformer, the W-phase transformer, and the neutral point of the secondary winding, all of which are connected in a Y configuration in the three-phase transformer unit.

6. The DC power supply comprises a positive DC power supply unit and a negative DC power supply unit, which are connected in series with each other at the power supply neutral point and each outputs the predetermined DC voltage. The three-phase inverter device comprises: a U-phase inverter unit that generates an internal U-phase voltage having phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the U-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage from the predetermined DC voltages from the positive DC power supply unit and the negative DC power supply unit, in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit; a V-phase inverter unit that generates an internal V-phase voltage having phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the V-phase of the predetermined zero-sequence-containing unbalanced three-phase voltage from the predetermined DC voltages from the positive DC power supply unit and the negative DC power supply unit, in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit; and the pulse modulation signal A three-phase four-wire inverter comprising: a W-phase inverter unit that generates an internal W-phase voltage having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the W-phase of a predetermined zero-sequence-containing unbalanced three-phase voltage from a predetermined DC voltage from a positive DC power supply unit and a negative DC power supply unit according to the W-phase pulse modulation signal from a generation circuit; the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit are connected between the positive electrode of the positive DC power supply unit and the negative electrode of the negative DC power supply unit, and outputs an internal zero-sequence-containing unbalanced three-phase voltage that includes the internal U-phase voltage, the internal V-phase voltage, and the internal W-phase voltage as the U-phase voltage, the V-phase voltage, and the W-phase voltage, respectively; The three-phase transformer comprises a three-phase five-legged core having U-legs, V-legs, W-legs, and a pair of magnetic leakage legs; a U-phase winding section provided on the U-phase leg; a V-phase winding section provided on the V-phase leg; and a W-phase winding section provided on the W-phase leg, wherein one end of the primary winding of the U-phase winding section, one end of the primary winding of the V-phase winding section, and one end of the primary winding of the W-phase winding section are Y-connected at the primary winding neutral point, and the secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, and the secondary winding of the W-phase winding section are Y-connected at the secondary winding neutral point, and the primary winding neutral point is connected to the power supply neutral point of the DC power supply. The internal U-phase voltage, internal V-phase voltage, and internal W-phase voltage from the three-phase four-wire inverter are input to the other end of the primary winding of the U-phase winding section, the other end of the primary winding of the V-phase winding section, and the other end of the primary winding of the W-phase winding section of the three-phase five-legged core transformer, respectively, and An unbalanced three-phase power supply device according to claim 1 or 2, wherein the internal zero-sequence-containing unbalanced three-phase voltage is converted according to the turns ratio to obtain an external zero-sequence-containing unbalanced three-phase voltage which is output by the secondary winding of the U-phase winding section, the V-phase winding section, the W-phase winding section, and the neutral point of the secondary winding of the three-phase five-legged core transformer, which is connected in a Y configuration.

7. The unbalanced three-phase power supply device is provided as described in claim 1, The DC power supply is a converter that converts the three-phase voltage of a power system into a DC voltage, and the secondary side of the three-phase transformer is the output terminal to which the device under evaluation is connected, in the evaluation power supply.

8. A control circuit includes: a current command generation unit that receives unbalanced three-phase current information, including phase command values ​​and amplitude command values ​​for the U-phase, V-phase, and W-phase of a zero-sequence-containing unbalanced three-phase current which is an unbalanced three-phase current containing a predetermined zero-sequence component, and generates U-phase current commands, V-phase current commands, and W-phase current commands having phases, frequencies, and active and reactive amplitudes corresponding to the phases and amplitudes of the U-phase, V-phase, and W-phase of the predetermined zero-sequence-containing unbalanced three-phase current, respectively, based on the unbalanced three-phase current information; and a pulse modulation signal generation circuit that outputs U-phase pulse modulation signals, V-phase pulse modulation signals, and W-phase pulse modulation signals corresponding to the U-phase current commands, V-phase current commands, and W-phase current commands generated by the current command generation unit. The system comprises a DC power supply that outputs a predetermined DC voltage or DC current, a U-phase inverter unit, a V-phase inverter unit, and a W-phase inverter unit, and the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit each generate U-phase currents, V-phase currents, and W-phase currents having phases, frequencies, and amplitudes corresponding to the phase command values ​​of the U-phase, V-phase, and W-phase and the amplitude command values ​​of the active and reactive components of a predetermined zero-sequence unbalanced three-phase current, respectively, using the predetermined DC voltage or DC current from the DC power supply, according to the U-phase pulse modulation signal, the V-phase pulse modulation signal, and the W-phase pulse modulation signal from the pulse modulation signal generation circuit, respectively. A main circuit comprising: a three-phase inverter device that outputs an internal zero-sequence-containing unbalanced three-phase current including the U-phase current, the V-phase current, and the W-phase current; and a three-phase transformer having a U-phase winding section, a V-phase winding section, a W-phase winding section, and a secondary winding neutral point, wherein the secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, and the secondary winding of the W-phase winding section are connected in a Y configuration, the secondary winding neutral point is the neutral point of the Y configuration, and the U-phase current, V-phase current, and W-phase current of the internal zero-sequence-containing unbalanced three-phase current from the three-phase inverter device are input to the primary winding of the U-phase winding section, the primary winding of the V-phase winding section, and the primary winding of the W-phase winding section, respectively; An unbalanced three-phase power supply device in which the DC power supply of the main circuit, the three-phase inverter device, and the three-phase transformer device have respective configurations and interconnections that enable the output of the zero-sequence component of an external zero-sequence unbalanced three-phase current obtained by converting the internal zero-sequence unbalanced three-phase current in the three-phase transformer according to the turns ratio, and the external zero-sequence unbalanced three-phase current is output by the secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, the secondary winding of the W-phase winding section, and the neutral point of the secondary winding of the three-phase transformer, which is connected in a Y configuration.

9. The main circuit includes a current sensor unit that detects the U-phase, V-phase, and W-phase currents of the internal zero-sequence-containing unbalanced three-phase current or the external zero-sequence-containing unbalanced three-phase current. The control circuit further comprises a current feedback control unit, The current command generation unit, A phase command value generation unit adds the phase command values ​​of the U-phase, V-phase, and W-phase of the predetermined zero-sequence-containing unbalanced three-phase current to the respective phases of the U-phase, V-phase, and W-phase of the reference internal three-phase sine wave, and outputs the U-phase phase command value, V-phase phase command value, and W-phase phase command value obtained by the addition. A three-phase sine wave generation unit compares the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value and their respective input timings generated by the phase command value generation unit with a sin table, and generates U-phase sine waves, V-phase sine waves, and W-phase sine waves having frequencies and reference amplitudes corresponding to the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value, respectively. A three-phase cosine wave generation unit compares the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value and their respective input timings generated by the phase command value generation unit with a cos table, and generates U-phase cosine waves, V-phase cosine waves, and W-phase cosine waves having phases, frequencies, and reference amplitudes corresponding to the U-phase phase command value, the V-phase phase command value, and the W-phase phase command value, respectively. A sine wave amplitude determination unit determines the amplitude of the U-phase sine wave, the V-phase sine wave, and the W-phase sine wave by multiplying the amplitude values ​​of the U-phase, V-phase, and W-phase sine waves generated by the three-phase sine wave generation unit by the effective amplitude command values ​​of the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase current, and thereby generates a U-phase sine wave command, a V-phase sine wave command, and a W-phase sine wave command. A cosine wave amplitude determination unit determines the amplitudes of the U-phase cosine wave, the V-phase cosine wave, and the W-phase cosine wave by multiplying the amplitude values ​​of the U-phase, V-phase, and W-phase cosine wave generated by the cosine wave amplitude value generation unit by the respective reactive amplitude command values ​​of the U-phase, V-phase, and W-phase of the predetermined zero-phase-containing unbalanced three-phase current, thereby generating U-phase cosine wave commands, V-phase cosine wave commands, and W-phase cosine wave commands. The system includes a current command amplitude determination unit that generates the U-phase current command, the V-phase current command, and the W-phase current command by adding the U-phase cosine wave command, the V-phase cosine wave command, and the W-phase cosine command, respectively, generated by the cosine wave amplitude determination unit, to the U-phase sine wave command, the V-phase sine wave command, and the W-phase sine wave command generated by the sine wave amplitude determination unit, respectively. The current feedback control unit, A current error generation unit generates U-phase current error, V-phase current error, and W-phase current error, which are errors in the U-phase, V-phase, and W-phase currents of the internal zero-sequence-containing unbalanced three-phase current or the external zero-sequence-containing unbalanced three-phase current detected by the current sensor unit, for the U-phase current command, V-phase current command, and W-phase current command generated by the current command amplitude determination unit, The system includes a current compensation unit that generates a U-phase current manipulation amount, a V-phase current manipulation amount, and a W-phase current manipulation amount by applying compensation to the U-phase current error, the V-phase current error, and the W-phase current error generated by the current error generation unit, respectively. The unbalanced three-phase power supply according to claim 8, wherein the pulse modulation signal generation circuit is a circuit that generates the U-phase pulse modulation signal, the V-phase pulse modulation signal, and the W-phase pulse modulation signal, which correspond to the U-phase current manipulation amount, the V-phase current manipulation amount, and the W-phase current manipulation amount generated by the current compensation unit, respectively.

10. The DC power supply comprises a U-phase DC power supply unit, a V-phase DC power supply unit, and a W-phase DC power supply unit, each outputting a predetermined DC voltage or DC current. The three-phase inverter device comprises a U-phase inverter section which generates an internal U-phase current having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the U-phase of a predetermined zero-sequence unbalanced three-phase current, using a predetermined DC voltage or DC current from the U-phase DC power supply section in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit; and a V-phase inverter section which generates an internal V-phase current having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the V-phase of a predetermined zero-sequence unbalanced three-phase current, using a predetermined DC voltage or DC current from the V-phase DC power supply section in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit. A three-phase inverter unit comprising: a single-phase V-phase inverter; a single-phase W-phase inverter that constitutes the W-phase inverter section and generates an internal W-phase current having a phase, frequency, and amplitude corresponding to the W-phase phase command value and amplitude command value of the predetermined zero-sequence-containing unbalanced three-phase current, using the predetermined DC voltage or DC current from the W-phase DC power supply section according to the W-phase pulse modulation signal from the pulse modulation signal generation circuit; and the U-phase inverter, the V-phase inverter, and the W-phase inverter output the internal zero-sequence-containing unbalanced three-phase current, which includes the internal U-phase current, the internal V-phase current, and the internal W-phase current as the U-phase current, the V-phase current, and the W-phase current, respectively. The three-phase transformer unit comprises a single-phase U-phase transformer constituting the U-phase winding section, a single-phase V-phase transformer constituting the V-phase winding section, and a single-phase W-phase transformer constituting the W-phase winding section, wherein the secondary windings of the U-phase transformer, the V-phase transformer, and the W-phase transformer are connected in a Y configuration, and the neutral point of the Y configuration is the neutral point of the secondary winding. The internal U-phase current, the internal V-phase current, and the internal W-phase current from the three-phase inverter unit are input to the primary winding of the U-phase transformer, the primary winding of the V-phase transformer, and the primary winding of the W-phase transformer, respectively, and An unbalanced three-phase power supply device according to claim 8 or 9, wherein the internal zero-sequence-containing unbalanced three-phase current is converted according to the turns ratio to produce an external zero-sequence-containing unbalanced three-phase current which is output by the secondary winding of the U-phase transformer, the V-phase transformer, the W-phase transformer, and the neutral point of the secondary winding, all of which are connected in a Y configuration in the three-phase transformer unit.

11. The DC power supply comprises a U-phase DC power supply unit, a V-phase DC power supply unit, and a W-phase DC power supply unit, each outputting a predetermined DC voltage or DC current. The three-phase inverter device comprises a U-phase inverter section comprising a single-phase U-phase inverter that generates an internal U-phase current having phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the U-phase of a predetermined zero-sequence unbalanced three-phase current, using a predetermined DC voltage or DC current from the DC power supply in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit, and a V-phase inverter section comprising a V-phase inverter that generates an internal V-phase current having phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the V-phase of a predetermined zero-sequence unbalanced three-phase current, using a predetermined DC voltage or DC current from the DC power supply in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit. A three-phase inverter unit comprising: a single-phase V-phase inverter; a single-phase W-phase inverter that constitutes the W-phase inverter section and generates an internal W-phase current having a phase, frequency, and amplitude corresponding to the W-phase phase command value and amplitude command value of a predetermined zero-sequence-containing unbalanced three-phase current using a predetermined DC voltage or DC current from the DC power supply in accordance with the W-phase pulse modulation signal from the pulse modulation signal generation circuit; and the U-phase inverter, the V-phase inverter, and the W-phase inverter output the internal zero-sequence-containing unbalanced three-phase current which includes the internal U-phase current, the internal V-phase current, and the internal W-phase current as the U-phase current, the V-phase current, and the W-phase current, respectively. The three-phase transformer comprises a three-phase five-legged core having U-legs, V-legs, W-legs, and a pair of magnetic leakage legs, a U-phase winding section provided on the U-phase leg, a V-phase winding section provided on the V-phase leg, and a W-phase winding section provided on the W-phase leg, wherein the secondary windings of the U-phase winding section, the V-phase winding section, and the W-phase winding section are connected in a Y configuration, and the neutral point of the Y configuration is the neutral point of the secondary winding. The internal U-phase current, the internal V-phase current, and the internal W-phase current from the three-phase inverter unit are input to the primary winding of the U-phase winding section, the primary winding of the V-phase winding section, and the primary winding of the W-phase winding section of the three-phase five-legged core transformer, respectively, and An unbalanced three-phase power supply device according to claim 8 or 9, wherein the internal zero-sequence-containing unbalanced three-phase current is converted according to the turns ratio to obtain an external zero-sequence-containing unbalanced three-phase current which is output by the secondary winding of the U-phase winding section, the V-phase winding section, the W-phase winding section, and the neutral point of the secondary winding of the three-phase five-legged iron core transformer which is connected in a Y configuration.

12. The DC power supply comprises a positive DC power supply unit and a negative DC power supply unit, which are connected in series with each other at the power supply neutral point and each outputs the predetermined DC voltage or DC current. The three-phase inverter device comprises a U-phase inverter unit that generates an internal U-phase current having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the U-phase of a predetermined zero-sequence-containing unbalanced three-phase current, using a predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit, and the three-phase inverter device comprises a V-phase inverter unit that generates an internal V-phase current having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the V-phase of a predetermined zero-sequence-containing unbalanced three-phase current, using a predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit, and the three-phase inverter device comprises a U-phase inverter unit that generates an internal V-phase current having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the V-phase of a predetermined zero-sequence-containing unbalanced three-phase current, using a predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit, and the three-phase The inverter device comprises a W-phase inverter unit that generates an internal W-phase current having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the W-phase of a predetermined zero-sequence-containing unbalanced three-phase current, using a predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the W-phase pulse modulation signal from the pulse modulation signal generation circuit, wherein the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit are connected between the positive electrode of the positive DC power supply unit and the negative electrode of the negative DC power supply unit, and outputs the internal zero-sequence-containing unbalanced three-phase current which includes the internal U-phase current, the internal V-phase current, and the internal W-phase current as the U-phase current, the V-phase current, and the W-phase current, respectively, in a three-phase four-wire inverter. The three-phase transformer unit comprises a single-phase U-phase transformer constituting the U-phase winding section, a single-phase V-phase transformer constituting the V-phase winding section, and a single-phase W-phase transformer constituting the W-phase winding section, wherein one end of the primary winding of the U-phase transformer, one end of the primary winding of the V-phase transformer, and one end of the primary winding of the W-phase transformer are Y-connected at the primary winding neutral point, and the secondary winding of the U-phase transformer, the secondary winding of the V-phase transformer, and the secondary winding of the W-phase transformer are Y-connected at the secondary winding neutral point, and the primary winding neutral point is connected to the power supply neutral point of the DC power supply. The internal U-phase current, the internal V-phase current, and the internal W-phase current from the three-phase four-wire inverter are input to the primary winding of the U-phase transformer, the primary winding of the V-phase transformer, and the primary winding of the W-phase transformer, respectively, and An unbalanced three-phase power supply device according to claim 8 or 9, wherein the internal zero-sequence-containing unbalanced three-phase current is converted according to the turns ratio to produce an external zero-sequence-containing unbalanced three-phase current which is output by the secondary winding of the U-phase transformer, the V-phase transformer, the W-phase transformer, and the neutral point of the secondary winding, all of which are connected in a Y configuration in the three-phase transformer unit.

13. The DC power supply comprises a positive DC power supply unit and a negative DC power supply unit, which are connected in series with each other at the power supply neutral point and each outputs the predetermined DC voltage or DC current. The three-phase inverter device comprises a U-phase inverter unit that generates an internal U-phase current having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the U-phase of a predetermined zero-sequence-containing unbalanced three-phase current, using a predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the U-phase pulse modulation signal from the pulse modulation signal generation circuit, and the three-phase inverter device comprises a V-phase inverter unit that generates an internal V-phase current having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the V-phase of a predetermined zero-sequence-containing unbalanced three-phase current, using a predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit, and the three-phase inverter device comprises a U-phase inverter unit that generates an internal V-phase current having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the V-phase of a predetermined zero-sequence-containing unbalanced three-phase current, using a predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the V-phase pulse modulation signal from the pulse modulation signal generation circuit, and the three-phase The inverter device comprises a W-phase inverter unit that generates an internal W-phase current having a phase, frequency, and amplitude corresponding to the phase command value and amplitude command value of the W-phase of a predetermined zero-sequence-containing unbalanced three-phase current, using a predetermined DC voltage or DC current from the positive DC power supply unit and the negative DC power supply unit in accordance with the W-phase pulse modulation signal from the pulse modulation signal generation circuit, wherein the U-phase inverter unit, the V-phase inverter unit, and the W-phase inverter unit are connected between the positive electrode of the positive DC power supply unit and the negative electrode of the negative DC power supply unit, and outputs the internal zero-sequence-containing unbalanced three-phase current which includes the internal U-phase current, the internal V-phase current, and the internal W-phase current as the U-phase current, the V-phase current, and the W-phase current, respectively, in a three-phase four-wire inverter. The three-phase transformer comprises a three-phase five-legged core having U-legs, V-legs, W-legs, and a pair of magnetic leakage legs; a U-phase winding section provided on the U-phase leg; a V-phase winding section provided on the V-phase leg; and a W-phase winding section provided on the W-phase leg, wherein one end of the primary winding of the U-phase winding section, one end of the primary winding of the V-phase winding section, and one end of the primary winding of the W-phase winding section are Y-connected at the primary winding neutral point, and the secondary winding of the U-phase winding section, the secondary winding of the V-phase winding section, and the secondary winding of the W-phase winding section are Y-connected at the secondary winding neutral point, and the primary winding neutral point is connected to the power supply neutral point of the DC power supply. The internal U-phase current, the internal V-phase current, and the internal W-phase current from the three-phase four-wire inverter are input to the primary winding of the U-phase winding section, the primary winding of the V-phase winding section, and the primary winding of the W-phase winding section of the three-phase five-legged core transformer, respectively, and An unbalanced three-phase power supply device according to claim 8 or 9, wherein the internal zero-sequence-containing unbalanced three-phase current is converted according to the turns ratio to obtain an external zero-sequence-containing unbalanced three-phase current which is output by the secondary winding of the U-phase winding section, the V-phase winding section, the W-phase winding section, and the neutral point of the secondary winding of the three-phase five-legged iron core transformer which is connected in a Y configuration.

14. The unbalanced three-phase power supply device is provided as described in claim 8, An evaluation power supply wherein the DC power supply is a converter that converts the three-phase voltage or three-phase current of a power system into a DC voltage or DC current, and the secondary side of the three-phase transformer is the output terminal to which the device under evaluation is connected.

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