Reference three-phase voltage signal generation device and reference three-phase voltage signal utilization device

Abstract

To quickly respond to sudden fluctuations in a three-phase voltage of an external three-phase power wiring.SOLUTION: A reference three-phase voltage signal generating device 100 includes an internal three-phase voltage signal generator 1, a reference three-phase voltage signal generating unit 2 that generates a reference three-phase voltage signal Vr by adding a three-phase voltage control variable Oabc to an internal three-phase voltage signal Vi from the internal three-phase voltage signal generator 1, a first Clarke transformer 3 that converts the reference three-phase voltage signal Vr into a reference two-phase voltage signal Vrαβ, an external voltage signal sensor unit 4, a second Clarke transformer 5 that converts the external three-phase voltage signal Ve into an external two-phase voltage signal Veαβ, an error generating unit 6 that generates a two-phase voltage error signal Eαβ that is the error of the reference two-phase voltage signal Vrαβ with respect to the external two-phase voltage signal Veαβ, a compensating unit 7 that applies compensation to the two-phase voltage error signal Eαβ to generate a two-phase voltage control variable Oαβ, and an inverse Clarke transformer 8 that converts the two-phase voltage control variable Oαβ into a three-phase voltage control variable Oabc and inputs it to the reference three-phase voltage signal generating unit 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a reference three-phase voltage signal generating device and a reference three-phase voltage signal utilizing device. [Background technology]

[0002] PLL (phase locked loop) circuits have been widely known. Patent Document 1 discloses an uninterruptible power source (UPS) that uses a PLL circuit in a power supply synchronization circuit that outputs a synchronized sine wave signal in phase with a commercial power supply. In this uninterruptible power supply, an inverter that is PWM controlled in accordance with the synchronized sine wave signal using the PLL circuit outputs an AC voltage synchronized with the voltage of the commercial power supply. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP-A-63-206164 (see especially FIG. 1 and the description from page 3, upper left column, line 12 to page 3, upper right column, line 3) Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, uninterruptible power supplies (UPSs) have been required to respond quickly to sudden fluctuations in the voltage of a commercial power supply. However, in the conventional UPSs described above, the zero-crossing points of an external AC voltage and an internal sine wave are used to detect the phase difference in the PLL circuit. In the zero-crossing point detection method, when the external AC voltage is, for example, 50 Hz, there are only one or two control opportunities (opportunities to detect zero-crossing points) per cycle. Therefore, due to the constraints imposed by the speed of the synchronization process, a fast response to sudden fluctuations in the voltage of the commercial power supply is not possible. Such a fast response to sudden fluctuations in the voltage of a commercial power supply may also be required in other power supply devices connected to a commercial power supply. Furthermore, a fast response to sudden fluctuations in the three-phase voltage of a general external three-phase power wiring is also desirable in power supply devices that synchronize the voltage of a general external three-phase power wiring.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a reference three-phase voltage signal generator and a reference three-phase voltage signal utilization device that can respond quickly to abrupt fluctuations in the three-phase voltage of external three-phase power wiring that is the target of synchronization, etc. [Means for solving the problem]

[0006] In order to achieve the above object, a reference three-phase voltage signal generating device according to an aspect of the present disclosure includes an internal three-phase voltage signal generator that generates internal three-phase voltage signals; a reference three-phase voltage signal generating unit that adds a three-phase voltage manipulation variable to the internal three-phase voltage signals from the internal three-phase voltage signal generator and outputs a reference three-phase voltage signal obtained by the addition to an external circuit; a first Clarke transforming unit that converts the reference three-phase voltage signals from the reference three-phase voltage signal generating unit into reference two-phase voltage signals in an αβ coordinate system by Clarke transform; an external voltage signal sensor unit that acquires external three-phase voltage signals from external three-phase power wiring; and a second Clarke transforming unit that applies Clarke transform to the external three-phase voltage signals from the external voltage signal sensor unit. a second Clarke transformation unit that generates external two-phase voltage signals in the αβ coordinate system by applying a Clarke transformation or Clarke transformation and multiplying by a rotation matrix with a 90° lead; an error generation unit that generates two-phase voltage error signals by generating errors of the reference two-phase voltage signals from the first Clarke transformation unit with respect to the external two-phase voltage signals from the second Clarke transformation unit; a compensation unit that generates two-phase voltage control variables by applying compensation to the two-phase voltage error signals from the error generation unit; and an inverse Clarke transformation unit that converts the two-phase voltage control variables from the compensation unit into the three-phase voltage control variables in the abc coordinate system by an inverse Clarke transformation and inputs the three-phase voltage control variables to the reference three-phase voltage signal generation unit.

[0007] Furthermore, a reference three-phase voltage signal utilization device according to another aspect of the present disclosure includes the above-described reference three-phase voltage signal generation device, and a three-phase inverter that is PWM controlled in response to the reference three-phase voltage signal to output a three-phase voltage synchronized with the three-phase voltage of the external three-phase power wiring.

[0008] The present disclosure advantageously provides a reference three-phase voltage signal generator and a reference three-phase voltage signal utilization device that can respond quickly to abrupt fluctuations in the three-phase voltage of an external three-phase power wiring that is the target of synchronization, etc. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a functional block diagram illustrating an example of the concept of a reference three-phase voltage signal generating device according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a functional block diagram illustrating an example of the configuration of a reference three-phase voltage signal generating device according to the second embodiment of the present disclosure. [Figure 3] FIG. 3 is a schematic diagram showing a principle model of a generator. [Figure 4] Figure 4 is a vector diagram of a Y-connection. [Figure 5] FIG. 5 is an explanatory diagram showing the relationship between the generator model and Euler's formula. [Figure 6] Figure 6 is a vector diagram that represents Euler's formula. [Figure 7] FIG. 7 is a schematic diagram showing rotor vectors. [Figure 8] FIG. 8 is a vector diagram illustrating the vector calculation for determining the manipulated variable rotor vector. [Figure 9] FIG. 9 is a diagram showing the vector locus of the manipulated variable rotor vector. [Figure 10] FIG. 10 is a waveform diagram showing the waveforms of signals at various parts in a simulation of a reference three-phase voltage signal generator in the case where the external three-phase voltage signal and the internal three-phase voltage signal differ only in phase. [Figure 11] FIG. 11 is a waveform diagram showing the waveforms of signals at various parts in a simulation of a reference three-phase voltage signal generator when the external three-phase voltage signal and the internal three-phase voltage signal have different frequencies. [Figure 12] FIG. 12 is a functional block diagram illustrating an example of the configuration of a reference three-phase voltage signal generating device according to the third embodiment of the present disclosure. [Figure 13A] FIG. 13A is a functional block diagram illustrating an example of the configuration of a reference three-phase voltage signal utilization device according to the fourth embodiment of the present disclosure. [Figure 13B] FIG. 13B is a functional block diagram illustrating an example of the configuration of a reference three-phase voltage signal utilization device according to the fifth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] A reference three-phase voltage signal generating device according to an aspect of the present disclosure includes an internal three-phase voltage signal generator that generates internal three-phase voltage signals; a reference three-phase voltage signal generating unit that adds a three-phase voltage manipulation variable to the internal three-phase voltage signals from the internal three-phase voltage signal generator and outputs a reference three-phase voltage signal obtained by the addition to an external device; a first Clarke transforming unit that converts the reference three-phase voltage signals from the reference three-phase voltage signal generating unit into reference two-phase voltage signals in an αβ coordinate system by Clarke transform; an external voltage signal sensor unit that acquires external three-phase voltage signals from external three-phase power wiring; and an error generating unit that generates two-phase voltage error signals by generating errors of the reference two-phase voltage signals from the first Clarke transformer with respect to the external two-phase voltage signals from the second Clarke transformer; a compensating unit that generates two-phase voltage control variables by applying compensation to the two-phase voltage error signals from the error generating unit; and an inverse Clarke transforming unit that converts the two-phase voltage control variables from the compensating unit into the three-phase voltage control variables in the abc coordinate system by an inverse Clarke transform and inputs the three-phase voltage control variables to the reference three-phase voltage signal generating unit.

[0011] Here, the "internal three-phase voltage signal" includes the "sine wave internal three-phase voltage signal" which is the active component and the "cosine wave internal three-phase voltage signal" which is the reactive component. The "external three-phase voltage signal" includes only the "sine wave external three-phase voltage signal" which is the active component. The "two-phase voltage signal" includes the "sine wave two-phase voltage signal" which is the active component and the "cosine wave reference two-phase voltage signal" which is the reactive component. The "two-phase voltage error signal" includes the "sine wave two-phase voltage error signal" which is the active component and the "cosine wave two-phase voltage error signal" which is the reactive component. The "two-phase voltage manipulated variable" includes the "sine wave two-phase voltage manipulated variable" which is the active component and the "cosine wave two-phase voltage manipulated variable" which is the reactive component. The "three-phase voltage manipulated variable" includes the "sine wave three-phase voltage manipulated variable" which is the active component and the "cosine wave three-phase voltage manipulated variable" which is the reactive component. These definitions are reasonable because the cosine wave internal three-phase voltage signals only lead the sine wave internal three-phase voltage signals by 90° (π / 2 [rad]).

[0012] According to this configuration, first, the three-phase voltage manipulation variables are added to the internal three-phase voltage signals from the internal three-phase voltage signal generator, and the reference three-phase voltage signals obtained by this addition are output to the outside. Next, the reference three-phase voltage signals from the reference three-phase voltage signal generator are transformed into reference two-phase voltage signals in the αβ coordinate system by Clarke transformation. Furthermore, the external three-phase voltage signals from the external voltage signal sensor unit are transformed into external two-phase voltage signals in the αβ coordinate system by applying the Clarke transformation or by applying the Clarke transformation and multiplying by a rotation matrix. Since the αβ coordinate system is an orthogonal coordinate system, the reference two-phase voltage signals and the external two-phase voltage signals specify a reference rotor vector and an external rotor vector, respectively. These reference rotor vector and external rotor vector rotate at angular velocities corresponding to the frequencies of the reference three-phase voltage signals and the external three-phase voltage signals before Clarke transformation, respectively.

[0013] Then, by generating an error of the reference two-phase voltage signals relative to the external two-phase voltage signals, a two-phase voltage error signal is generated, and compensation is applied to generate a two-phase voltage manipulated variable, which corresponds to a process in which the reference rotor vector is subtracted from the external rotor vector by vector calculation to obtain a manipulated variable rotor vector.

[0014] Next, the two-phase voltage control variables are transformed into three-phase voltage control variables in the abc coordinate system by the inverse Clarke transformation, and the three-phase voltage control variables are added to the internal three-phase voltage signals. This process corresponds to adding the control variable rotor vector to the reference rotor vector on the time axis.

[0015] By performing the above-described closed-loop feedback control, the reference rotor vector is made to coincide with the external rotor vector or to have a 90° leading phase difference with respect to the external rotor vector, thereby generating a reference three-phase voltage signal that is synchronized with the external three-phase voltage signals or has a phase difference corresponding to the reactive component.

[0016] The rate of the above-described reference three-phase voltage signal generation process is determined by the sampling rate of the external three-phase voltage signal. This sampling rate can be, for example, 6 kHz. If the external three-phase voltage signal is 50 Hz, there are 120 control opportunities (opportunities to acquire the external three-phase voltage signal) in one cycle of the external three-phase voltage signal. On the other hand, with the zero-crossing point detection method, if the external three-phase voltage is 50 Hz, there are only one or two control opportunities (opportunities to detect zero-crossing points) in one cycle of the external three-phase voltage signal. Therefore, the above-described configuration has a significantly faster reference three-phase voltage signal generation process (synchronization or 90° leading phase process) than conventional zero-crossing point detection methods. As a result, devices that use reference three-phase voltage signals can quickly respond to sudden fluctuations in the external three-phase power voltage, which is the target of synchronization, etc.

[0017] The internal U-phase voltage signal, the internal V-phase voltage signal, and the internal W-phase voltage signal of the internal three-phase voltage signal are the internal a-voltage signal, the internal b-voltage signal, and the internal c-voltage signal in an abc coordinate system, respectively; the external U-phase voltage signal, the external V-phase voltage signal, and the external W-phase voltage signal of the external three-phase voltage signal are the external a-voltage signal, the external b-voltage signal, and the external c-voltage signal in an abc coordinate system, respectively; and the reference three-phase voltage signal generating unit generates the internal a-voltage signal, the internal b-voltage signal, and the internal c-voltage signal of the internal three-phase voltage signal from the internal three-phase voltage signal generator. a signal generating unit that adds the a-voltage control amount, the b-voltage control amount, and the c-voltage control amount of the three-phase voltage control amounts to the reference three-phase voltage signal, respectively, and outputs the reference three-phase voltage signals obtained by the addition, including a reference U-phase voltage signal that is a reference a-voltage signal, a reference V-phase voltage signal that is a reference b-voltage signal, and a reference W-phase voltage signal that is a reference c-voltage signal, to an external unit; and the first Clarke transformer converts the reference three-phase voltage signals including the reference a-voltage signal, the reference b-voltage signal, and the reference c-voltage signal from the reference three-phase voltage signal generating unit into a reference α-voltage signal in an αβ coordinate system by Clarke transformation. a conversion unit that converts the external two-phase voltage signals from the external voltage signal sensor unit into the reference two-phase voltage signals including the external a voltage signal, the external b voltage signal, and the external c voltage signal, and generates the external two-phase voltage signals including the external α voltage signal and the external β voltage signal of an αβ coordinate system by applying a Clarke transformation or applying a Clarke transformation and multiplying by a rotation matrix with a 90° lead to the external three-phase voltage signals including the external a voltage signal, the external b voltage signal, and the external c voltage signal from the external voltage signal sensor unit; an error generating unit that generates the two-phase voltage error signals including an α voltage error signal and a β voltage error signal that are errors of the reference α voltage signal and the reference β voltage signal of the reference two-phase voltage signal from the first Clarke transformer for the external α voltage signal and the external β voltage signal, respectively; and the compensating unit generates the two-phase voltage control variables including an α voltage control variable and a β voltage control variable by applying compensation to the α voltage error signal and the β voltage error signal of the two-phase voltage error signal from the error generating unit, respectively; and the inverse Clarke transformerThe converter may be configured to convert the two-phase voltage control amount, including the α voltage control amount and the β voltage control amount, from the compensation unit into the three-phase voltage control amount, including the a voltage control amount, the b voltage control amount, and the c voltage control amount in an abc coordinate system by inverse Clarke transformation, and input the three-phase voltage control amount to the reference three-phase voltage signal generator.

[0018] Here, the "reference a voltage signal," "reference b voltage signal," and "reference c voltage signal" respectively include the "sine wave reference a voltage signal," "cosine wave reference a voltage signal," "sine wave reference b voltage signal," "cosine wave reference b voltage signal," and "sine wave reference c voltage signal," and "cosine wave reference c voltage signal." The "external a voltage signal," "external b voltage signal," and "external c voltage signal" respectively include the "sine wave external a voltage signal," "cosine wave external a voltage signal," "sine wave external b voltage signal," "cosine wave external b voltage signal," and "sine wave external c voltage signal."

[0019] The "reference alpha voltage signal" and the "reference beta voltage signal" respectively include the "sine wave reference alpha voltage signal" and the "cosine wave reference alpha voltage signal," and the "sine wave reference beta voltage signal" and the "cosine wave reference beta voltage signal." The "external alpha voltage signal" and the "external beta voltage signal" respectively include the "sine wave external alpha voltage signal" and the "cosine wave external alpha voltage signal," and the "sine wave external beta voltage signal" and the "cosine wave external beta voltage signal."

[0020] The "α voltage error signal" and "β voltage error signal" include the "sine wave α voltage error signal" and "cosine wave α voltage error signal" and the "sine wave β voltage error signal" and "cosine wave β voltage error signal", respectively.

[0021] The "α voltage control amount" and the "β voltage control amount" respectively include the "sine wave α voltage control amount" and the "cosine wave α voltage control amount", and the "sine wave β voltage control amount" and the "cosine wave β voltage control amount".

[0022] According to this configuration, a reference three-phase voltage generating device can be suitably constructed.

[0023] the reference three-phase voltage signal generation unit is a signal generation unit that adds a sinusoidal three-phase voltage manipulation variable to the internal three-phase voltage signal from the internal three-phase voltage signal generator and outputs a sinusoidal reference three-phase voltage signal obtained by the addition to an external device; the first Clarke transformation unit is a conversion unit that converts the sinusoidal reference three-phase voltage signal from the reference three-phase voltage signal generation unit into a sinusoidal reference two-phase voltage signal in an αβ coordinate system by Clarke transformation; and the second Clarke transformation unit is a conversion unit that generates a sinusoidal external two-phase voltage signal in an αβ coordinate system by applying Clarke transformation to the external three-phase voltage signal from the external voltage signal sensor unit; The error generating unit may be an error generating unit that generates a sinusoidal two-phase voltage error signal that is an error between the sinusoidal reference two-phase voltage signal from the first Clarke transformer and the sinusoidal external two-phase voltage signal from the second Clarke transformer, the compensating unit may be a compensating unit that generates a sinusoidal two-phase voltage control variable by applying compensation to the sinusoidal two-phase voltage error signal from the error generating unit, and the inverse Clarke transforming unit may be a converting unit that converts the sinusoidal two-phase voltage control variable from the compensating unit into the sinusoidal three-phase voltage control variable in an abc coordinate system by an inverse Clarke transform and inputs the sinusoidal three-phase voltage control variable to the reference three-phase voltage signal generating unit.

[0024] According to this configuration, the external three-phase voltage signal is a sinusoidal external three-phase voltage signal that is an active component. The second Clarke transformer generates sinusoidal external two-phase voltage signals in the αβ coordinate system by applying a Clarke transform to the sinusoidal external three-phase voltage signal. The error generator generates sinusoidal two-phase voltage error signals based on the sinusoidal external two-phase voltage signals. The compensator generates sinusoidal two-phase voltage control variables based on the sinusoidal two-phase voltage error signals. The inverse Clarke transformer converts the sinusoidal two-phase voltage control variables into sinusoidal three-phase voltage control variables by the inverse Clarke transform. The reference three-phase voltage signal generator adds the sinusoidal three-phase voltage control variables to the internal three-phase voltage signals from the internal three-phase voltage signal generator and outputs the sinusoidal reference three-phase voltage signals obtained by the addition to the outside. Then, by performing the above-described closed-loop feedback control, the sinusoidal reference three-phase voltage signals are synchronized with the external three-phase voltage signals. As a result, it is possible to provide a reference three-phase voltage signal generating device that outputs a sinusoidal reference three-phase voltage signal synchronized with the three-phase voltage of the active component of the external three-phase power.

[0025] the reference three-phase voltage signal generation unit adds a cosine-wave three-phase voltage manipulation variable to the internal three-phase voltage signal from the internal three-phase voltage signal generator and outputs a cosine-wave reference three-phase voltage signal obtained by the addition to an external unit; the first Clarke transformation unit transforms the cosine-wave reference three-phase voltage signal from the reference three-phase voltage signal generation unit into a cosine-wave reference two-phase voltage signal in an αβ coordinate system by Clarke transformation; the second Clarke transformation unit generates a sinusoidal external two-phase voltage signal in an αβ coordinate system by applying Clarke transformation to the external three-phase voltage signal from the external voltage signal sensor unit; and and a rotation matrix multiplication unit that generates a cosine wave two-phase voltage signal, the error generation unit being an error generation unit that generates a cosine wave two-phase voltage error signal that is an error between the cosine wave external two-phase voltage signal from the rotation matrix multiplication unit of the second Clarke transformation unit and the cosine wave reference two-phase voltage signal from the first Clarke transformation unit; the compensation unit being a compensation unit that generates a cosine wave two-phase voltage manipulated variable by applying compensation to the cosine wave two-phase voltage error signal from the error generation unit; and the inverse Clarke transformation unit being a conversion unit that converts the cosine wave two-phase voltage manipulated variable from the compensation unit into the cosine wave three-phase voltage manipulated variable in an abc coordinate system by an inverse Clarke transformation, and inputs the cosine wave three-phase voltage manipulated variable to the reference three-phase voltage signal generation unit.

[0026] According to this configuration, the internal three-phase voltage signals are initially changed in phase for synchronization by feedback control, so the initial phase is not particularly limited. The external three-phase voltage signals are sinusoidal external three-phase voltage signals that are active components. A second Clarke transformer applies a Clarke transform to the sinusoidal external three-phase voltage signals to generate sinusoidal external two-phase voltage signals in the αβ coordinate system, and multiplies the sinusoidal external two-phase voltage signals by a rotation matrix with a 90° lead to generate cosine-wave external two-phase voltage signals. An error generator generates cosine-wave two-phase voltage error signals based on the cosine-wave external two-phase voltage signals. A compensator generates cosine-wave two-phase voltage control variables based on the cosine-wave two-phase voltage error signals. An inverse Clarke transformer converts the cosine-wave two-phase voltage control variables into cosine-wave three-phase voltage control variables using an inverse Clarke transform. The reference three-phase voltage signal generator adds the cosine-wave three-phase voltage manipulation amount to the internal three-phase voltage signal from the internal three-phase voltage signal generator and outputs the cosine-wave reference three-phase voltage signal obtained by this addition to the outside. The above-described closed-loop feedback control causes the cosine-wave reference three-phase voltage to have a phase corresponding to a cosine wave relative to the sine-wave external three-phase power voltage. As a result, a reference three-phase voltage signal generator can be provided that outputs a cosine-wave reference three-phase voltage signal corresponding to the three-phase voltage signal of the reactive component of the external three-phase power.

[0027] The compensator may be a compensator that performs PI compensation on the two-phase voltage error signals. With this configuration, compensation can be suitably applied to the two-phase voltage error signals.

[0028] Furthermore, a reference three-phase voltage signal utilization device according to another aspect of the present disclosure includes any one of the reference three-phase voltage signal generation devices described above, and a three-phase inverter that is PWM controlled in response to the reference three-phase voltage signal to output a three-phase voltage synchronized with the three-phase voltage of the external three-phase power wiring.

[0029] This configuration makes it possible to provide a reference three-phase voltage signal utilization device that can respond quickly to abrupt fluctuations in the three-phase voltage of the external three-phase power wiring that is the target of synchronization or the like.

[0030] The reference three-phase voltage signal generating device may be a device that outputs the reference three-phase voltage signal synchronized with a three-phase voltage of a power supply system serving as the external three-phase power wiring from the reference three-phase voltage signal generating unit, and the three-phase inverter may be a three-phase inverter that outputs a three-phase voltage synchronized with the three-phase voltage of the power supply system by being PWM controlled in accordance with the reference three-phase voltage signal.

[0031] This configuration makes it possible to provide a system-interconnected power supply device that can respond quickly to abrupt fluctuations in the three-phase voltage of the power supply system that is the target of synchronization or the like.

[0032] 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 in waveform diagrams may not be accurate. Furthermore, the present disclosure is not limited to the following embodiments.

[0033] (Embodiment 1)

[0034] [composition] FIG. 1 is a functional block diagram showing an example of the concept of a reference three-phase voltage signal generating device 100 according to a first embodiment of the present disclosure.

[0035] Referring to FIG. 1, the reference three-phase voltage signal generating device 100 of the first embodiment includes an internal three-phase voltage signal generator 1, a reference three-phase voltage signal generating unit 2, a first Clarke transformer 3, an external voltage signal sensor unit 4, a second Clarke transformer 5, an error generating unit 6, a compensating unit 7, and an inverse Clarke transformer 8.

[0036] An internal three-phase voltage signal generator 1 generates an internal three-phase voltage signal Vi. A reference three-phase voltage signal generator 2 adds a three-phase voltage control variable Oabc to the internal three-phase voltage signal Vi from the internal three-phase voltage signal generator 1, and outputs a reference three-phase voltage signal Vr obtained by this addition to the outside. A first Clarke transformer 3 transforms the reference three-phase voltage signal Vr from the reference three-phase voltage signal generator 2 into a reference two-phase voltage signal Vrαβ in the αβ coordinate system by Clarke transformation.

[0037] Meanwhile, the external voltage signal sensor unit 4 acquires the external three-phase voltage signal Ve from the external three-phase power wiring 10. The second Clarke transformer 5 applies the Clarke transform to the external three-phase voltage signal Ve from the external voltage signal sensor unit 4, or applies the Clarke transform and multiplies it by a rotation matrix with a 90° lead, to generate an external two-phase voltage signal Veαβ in the αβ coordinate system.

[0038] The error generating unit 6 generates a two-phase voltage error signal Eαβ by generating an error between the reference two-phase voltage signal Vrαβ from the first Clarke transformer 3 and the external two-phase voltage signal Veαβ from the second Clarke transformer 5. The compensating unit 7 generates a two-phase voltage control variable Oαβ by applying compensation to the two-phase voltage error signal Eαβ from the error generating unit 6. The inverse Clarke transformer 8 converts the two-phase voltage control variable Oαβ from the compensating unit 7 into a three-phase voltage control variable Oabc in the abc coordinate system by inverse Clarke transformation and inputs it to the reference three-phase voltage signal generating unit 2.

[0039] [Operation] In the reference three-phase voltage signal generating device 100, first, the three-phase voltage control variable Oabc is added to the internal three-phase voltage signal Vi from the internal three-phase voltage signal generator 1, and the reference three-phase voltage signal Vr obtained by this addition is output to the outside. Next, the reference three-phase voltage signal Vr from the reference three-phase voltage signal generating unit 2 is transformed into a reference two-phase voltage signal Vrαβ in the αβ coordinate system by Clarke transformation. Furthermore, the external three-phase voltage signal Ve from the external voltage signal sensor unit 4 is transformed into an external two-phase voltage signal Veαβ in the αβ coordinate system by applying the Clarke transformation or by applying the Clarke transformation and multiplying it by a rotation matrix with a 90° lead. Because the αβ coordinate system is an orthogonal coordinate system, the reference two-phase voltage signal Vrαβ and the external two-phase voltage signal Veαβ identify the reference rotor vector and the external rotor vector, respectively. The reference rotor vector and the external rotor vector rotate at angular velocities corresponding to the frequency of the reference three-phase voltage signal Vr before Clarke transformation and the frequency of the external three-phase voltage signal Ve, respectively.

[0040] Next, the error of the reference two-phase voltage signal Vrαβ with respect to the external two-phase voltage signal Veαβ is generated to generate a two-phase voltage error signal Eαβ, which is then compensated to generate a two-phase voltage manipulated variable Oαβ. This process corresponds to the process of subtracting the reference rotor vector from the external rotor vector by vector calculation to obtain the manipulated variable rotor vector.

[0041] Next, this two-phase voltage control input Oαβ is transformed into a three-phase voltage control input Oabc in the abc coordinate system by inverse Clarke transformation, and this three-phase voltage control input Oabc is added to the internal three-phase voltage signal Vi. This process corresponds to adding the control input rotor vector to the reference rotor vector on the time axis.

[0042] By performing the above-described closed-loop feedback control, the reference rotor vector is made to coincide with or have a 90° lead phase difference with respect to the external rotor vector, thereby generating a reference three-phase voltage signal Vr that is synchronized with the external three-phase voltage signal Ve or has a phase difference corresponding to the reactive component. The reference rotor vector, external rotor vector, and manipulated variable rotor vector will be described in detail in embodiment 2.

[0043] The rate of the above-described reference three-phase voltage signal generation process is determined by the sampling period of the external three-phase voltage signal Ve. This sampling frequency can be, for example, 6 kHz. If the external three-phase voltage signal Ve is 50 Hz, there are 120 control opportunities (opportunities to acquire the external three-phase voltage signal) per cycle. On the other hand, in the case of the zero-crossing point detection method, if the external three-phase voltage signal Ve is 50 Hz, there are only one or two control opportunities (opportunities to detect zero-crossing points) per cycle. Therefore, the reference three-phase voltage signal generator 100 performs the reference three-phase voltage signal generation process (synchronization or 90° lead phase process) much faster than conventional zero-crossing point detection methods. As a result, devices using the reference three-phase voltage signal Vr can respond quickly to sudden fluctuations in the voltage of the external three-phase power wiring 10.

[0044] The reference three-phase voltage signal generating device 100 of the first embodiment includes an embodiment 2 in which the second Clarke transformer 5 only applies the Clarke transform to the external three-phase voltage signal Ve to generate a sine wave reference three-phase voltage signal, and an embodiment 3 in which the second Clarke transformer 5 applies the Clarke transform to the external three-phase voltage signal Ve and multiplies it by a rotation matrix with a 90° lead to generate a cosine wave reference three-phase voltage signal.

[0045] The detailed configuration of the first embodiment will be explained in the following second and third embodiments.

[0046] (Embodiment 2) The reference three-phase voltage signal generator 100A according to the second embodiment differs from the reference three-phase voltage signal generator 100 according to the first embodiment in that the second Clarke transformer 5 only applies Clarke transform to the external three-phase voltage signal Ve. Therefore, the reference three-phase voltage signal generator 100A generates a sinusoidal reference three-phase voltage signal Vrs.

[0047] [composition] 2 is a functional block diagram showing an example of the configuration of a reference three-phase voltage signal generating device 100A according to the second embodiment of the present disclosure. The configuration of the reference three-phase voltage signal generating device 100A will be described in detail below with reference to FIG.

[0048] <Internal three-phase voltage signal generator 1> The internal three-phase voltage signal generator 1 generates an internal three-phase voltage signal Vi including an internal U-phase voltage signal Viu, an internal V-phase voltage signal Viv, and an internal W-phase voltage signal Viw. These internal U-phase voltage signal Viu, internal V-phase voltage signal Viv, and internal W-phase voltage signal Viw are the internal a-voltage signal, internal b-voltage signal, and internal c-voltage signal in the abc coordinate system, respectively.

[0049] There are no particular limitations on the internal three-phase voltage signal generator 1 as long as it can generate a sine wave signal. Examples of the internal three-phase voltage signal generator 1 include a CR oscillator circuit, a Hartley oscillator circuit, and a Colpitts oscillator circuit.

[0050] <Reference three-phase voltage signal generation unit 2>, The reference three-phase voltage signal generating unit 2 adds the sinusoidal three-phase voltage control variables, ie, the sinusoidal a-voltage control variable Oas, the sinusoidal b-voltage control variable Obs, and the sinusoidal c-voltage control variable Ocs, to the internal a-voltage signal, internal b-voltage signal, and internal c-voltage signal of the internal three-phase voltage signal Vi from the internal three-phase voltage signal generator 1, respectively, and outputs to the outside a sinusoidal reference three-phase voltage signal Vrs obtained by this addition, which includes the sinusoidal reference U-phase voltage signal Vrus, which is the sinusoidal reference a-voltage signal, the sinusoidal reference V-phase voltage signal Vrvs, which is the sinusoidal reference b-voltage signal, and the sinusoidal reference W-phase voltage signal Vrws, which is the sinusoidal reference c-voltage signal.

[0051] There are no particular limitations on the reference three-phase voltage signal generator 2 as long as it can add signals. The reference three-phase voltage signal generator 2 is configured, for example, with three adders for the U phase, V phase, and W phase. These adders may be configured as either electronic circuits or software.

[0052] <First Clark Conversion Unit 3> The first Clarke transformer 3 converts the sinusoidal reference three-phase voltage signal Vrs, which includes the sinusoidal reference a voltage signal (sinusoidal reference U-phase voltage signal Vrus), the sinusoidal reference b voltage signal (sinusoidal reference V-phase voltage signal Vrvs), and the sinusoidal reference c voltage signal (sinusoidal reference W-phase voltage signal Vrws) from the reference three-phase voltage signal generator 2, into a sinusoidal reference two-phase voltage signal Vrαβs, which includes a sinusoidal reference α voltage signal Vrαs and a sinusoidal reference β voltage signal Vrβs in the αβ coordinate system, by Clarke transformation.

[0053] There are no particular limitations on the first Clarke conversion unit 3 as long as it can perform Clarke conversion. The first Clarke conversion unit 3 is configured, for example, by software.

[0054] <External voltage signal sensor unit 4> The external voltage signal sensor unit 4 acquires an external three-phase voltage signal Ve, including an external U-phase voltage signal Veu, an external V-phase voltage signal Vev, and an external W-phase voltage signal Vew, from the external three-phase power wiring 10. The external U-phase voltage signal Veu, the external V-phase voltage signal Vev, and the external W-phase voltage signal Vew are the external a-voltage signal, the external b-voltage signal, and the external c-voltage signal in the abc coordinate system, respectively.

[0055] The external voltage signal sensor unit 4 is composed of an external U-phase voltage signal sensor, an external V-phase voltage signal sensor, and an external W-phase voltage signal sensor. There are no particular limitations on the external voltage signal sensor unit 4 as long as it can acquire the external three-phase voltage signal Ve. Examples of voltage sensors include a voltmeter and a Hall element.

[0056] <Second Clark Conversion Unit 5> The second Clarke transformation unit 5 converts the external three-phase voltage signal Ve, which includes the external a voltage signal (external U-phase voltage signal Veu), the external b voltage signal (external V-phase voltage signal Vev), and the external c voltage signal (external W-phase voltage signal Vew) from the external voltage signal sensor unit 4, into a sinusoidal external two-phase voltage signal Veαβs, which includes a sinusoidal external α voltage signal Veαs and a sinusoidal external β voltage signal Veβs in the αβ coordinate system, by Clarke transformation.

[0057] There are no particular limitations on the second Clarke conversion unit 5 as long as it can perform Clarke conversion. The second Clarke conversion unit 5 is configured, for example, by software.

[0058] <Error generation section 6> The error generating unit 6 generates a sinusoidal two-phase voltage error signal Eαβs including a sinusoidal α voltage error signal Eαs and a sinusoidal β voltage error signal Eβs which are errors between the sinusoidal external α voltage signal Veαs and the sinusoidal external β voltage signal Veβs of the sinusoidal external two-phase voltage signal Veαβs from the second Clarke transformer 5 and the sinusoidal reference α voltage signal Vrαs and the sinusoidal reference β voltage signal Vrβs of the sinusoidal reference two-phase voltage signal Vrαβs from the first Clarke transformer 3.

[0059] The error generating unit 6 is composed of, for example, two subtractors, one for generating the sinusoidal α-voltage error signal Eαs and the other for generating the sinusoidal β-voltage error signal Eβs. The subtractor for generating the sinusoidal α-voltage error signal Eαs subtracts the sinusoidal reference α-voltage signal Vrαs from the sinusoidal external α-voltage signal Veαs. The subtractor for generating the sinusoidal β-voltage error signal Eβs subtracts the sinusoidal reference β-voltage signal Vrβs from the sinusoidal external β-voltage signal Veβs. These subtractors may be composed of either electronic circuits or software.

[0060] The error generator 6 may also include a phase inverting unit that inverts the phases of the sinusoidal reference α voltage signal Vrαs and the sinusoidal reference β voltage signal Vrβs of the sinusoidal reference two-phase voltage signal Vrαβs, and an adder that adds the sinusoidal reference α voltage signal Vrαs and the sinusoidal reference β voltage signal Vrβs of the phase-inverted sinusoidal reference two-phase voltage signal Vrαβs to the sinusoidal external α voltage signal Veαs and the sinusoidal external β voltage signal Veβs of the sinusoidal external two-phase voltage signal Veαβs, respectively. The phase inverting unit and the subtracting unit may be implemented by either electronic circuits or software.

[0061] <Compensation section 7> The compensator 7 generates a sinusoidal two-phase voltage control variable Oαβs including a sinusoidal α voltage control variable Oαs and a sinusoidal β voltage control variable Oβs by applying compensation to the sinusoidal α voltage error signal Eαs and the sinusoidal β voltage error signal Eβs of the sinusoidal two-phase voltage error signal Eαβs from the error generator 6. Examples of compensation that can be used include P compensation, PI compensation, and PID compensation. Here, for example, PI compensation is used. The compensator 7 may be configured as either an electronic circuit or software.

[0062] <Inverse Clarke Transformation Unit 8> The inverse Clarke transformer 8 converts the sinusoidal two-phase voltage control variable Oαβs, which includes the sinusoidal α voltage control variable Oαs and the sinusoidal β voltage control variable Oβs, from the compensator 7 by inverse Clarke transform into a sinusoidal three-phase voltage control variable Oabcs, which includes a sinusoidal a voltage control variable Oas, a sinusoidal b voltage control variable Obs, and a sinusoidal c voltage control variable Ocs in the abc coordinate system, and inputs this to the reference three-phase voltage signal generator 2. The inverse Clarke transformer 8 is not particularly limited as long as it can perform the inverse Clarke transform. The inverse Clarke transformer 8 may be configured, for example, by software.

[0063] <Software configuration> As described above, the reference three-phase voltage signal generator 2, the first Clarke transformer 3, the second Clarke transformer 5, the error generator 6, the compensator 7, and the inverse Clarke transformer 8 can be configured by software. In this case, for example, a computing unit having a processor and memory is used, and a predetermined program for executing the functions of the reference three-phase voltage signal generator 2, the first Clarke transformer 3, the second Clarke transformer 5, the error generator 6, the compensator 7, and the inverse Clarke transformer 8 is stored in the memory of the computing unit. The processor reads and executes this predetermined program, thereby realizing the reference three-phase voltage signal generator 2, the first Clarke transformer 3, the second Clarke transformer 5, the error generator 6, the compensator 7, and the inverse Clarke transformer 8 as functional blocks. In this case, the computing unit operates as the reference three-phase voltage signal generator 2, the first Clarke transformer 3, the second Clarke transformer 5, the error generator 6, the compensator 7, and the inverse Clarke transformer 8. This computing unit can be configured, for example, by a computer, a personal computer, a microcontroller, an MPU, an FPGA (Field Programmable Gate Array), a PLC (Programmable Logic Controller), or the like.

[0064] 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.

[0065] <External three-phase power wiring 10> The external three-phase power wiring 10 is not particularly limited as long as it is an external three-phase power source that the reference three-phase voltage signal generating device 100A is intended to synchronize, etc. Examples of the external three-phase power source include a commercial power source (power supply system) and a general three-phase power source other than a commercial power source.

[0066] [principle] Because the present disclosure is original, its principles will be explained step by step.

[0067] <Clarke transform and inverse Clarke transform> Clarke transformation is also known as three-phase to two-phase transformation or abc-αβ transformation. To understand it, it is necessary to understand the principles of generators. Figure 3 is a schematic diagram showing the principle model of a generator. Figure 4 is a vector diagram of a Y-connection.

[0068] Referring to Figure 3, three coils 31-33—U-phase coil 31, V-phase coil 32, and W-phase coil 33—are arranged at a bank angle of 120°, with a magnet 34 positioned at their center. This magnet 34 is called the rotor. This rotor rotates counterclockwise at an angular velocity of ω. When the rotor approaches coils 31-33, a voltage is induced in the coils 31-33. This is called electromagnetic induction. The arrangement of coils 31-33 forms a three-phase Y connection. However, the phase order appears reversed. This is because Figure 3 depicts a rotor rotating while the coils are stationary. From the perspective of someone riding on the rotating rotor, coils 31-33 appear to rotate clockwise. They should pass in front of you in the order U-phase → V-phase → W-phase. This results in the familiar Y-connection vector diagram shown in Figure 4.

[0069] Figure 5 is an explanatory diagram showing the relationship between the generator model and Euler's formula. In Figure 5, the angular velocity ω = 2πf [rad / s] and the frequency f = 50 [Hz]. Assume that the angular velocity ω and time t are synchronized.

[0070] Returning to the original discussion, if we focus on the U-phase coil 31 of the generator model, the relationship in Figure 5 becomes clear. If we plot the vertices of Figure 5, assuming the vector in the upper left corner to represent the rotor, sine and cosine waves appear. The rotor approaches coil 31 closest when it is horizontal, and this is when the greatest voltage is induced. Therefore, the cosine wave in Figure 5 is a waveform generally known as a sine wave, and represents the active component. On the other hand, the sine wave represents the reactive component.

[0071] Therefore, the vector in the upper left of Figure 5 can be expressed mathematically as the following two equations. The following two equations are "Euler's formula."

[0072] Aejωt=A(cosωt+jsinωt) Aejθ=A(cosθ+jsinθ) Figure 6 is a vector diagram that expresses "Euler's formula" as a vector. When "Euler's formula" is expressed as a vector, it is shown in Figure 6. In other words, the rotor can be expressed as a combination of cosine wave and sine wave components. Here, we focus on the U-phase coil 31, but the same can be said for the V-phase coil 32 and the W-phase coil 33. This allows the three phases to be expressed collectively.

[0073] In other words, the "three waveforms of three phases" can be expressed as "two waveforms (cos wave / sin wave) obtained by decomposing the rotor vector." This is why it is called "three-phase to two-phase transformation." Furthermore, if the "three waveforms of three phases" are [abc], and the cos wave of the "two waveforms (cos wave / sin wave) obtained by decomposing the rotor vector" is called α and the sin wave is called β, it is also called "abc-αβ transformation."

[0074] As with general vectors, scalar quantities and angles can be calculated using the following two formulas.

[0075]

number

[0076]

number

[0077] <How to apply Clarke transform and inverse Clarke transform> FIG. 7 is a schematic diagram showing rotor vectors. It shows the external rotor vector R1 of the external sine wave V1 and the internal rotor vector R2 of the internal sine wave V2 at a given moment. Referring to FIG. 7, when the external rotor vector R1 of the external sine wave V1 and the internal rotor vector R2 of the internal sine wave V2 have different frequencies, their angular velocities ω1 and ω2 are also different. To synchronize the phase of the internal sine wave V2 with the phase of the external sine wave V1, the internal rotor vector R2 of the internal sine wave V2 can be made to coincide with the external rotor vector R1 of the external sine wave V1. One possible method for achieving this is to add an appropriate control variable rotor vector R3 to the internal rotor vector R2 to make the internal rotor vector R2 coincide with the external rotor vector R1. This appropriate control variable rotor vector R3 can be calculated by vector synthesis. Since the external rotor vector R1 and the internal rotor vector R2 rotate at angular velocities ω1 and ω2, respectively, the manipulated variable rotor vector R3 also rotates at an angular velocity ω3 corresponding to the angular velocities ω1 and ω2.

[0078] Figure 8 is a vector diagram illustrating the vector calculation used to calculate the manipulated variable rotor vector R3. Referring to Figure 8, the α and β of the external rotor vector R1 and the internal rotor vector R2 are calculated using Clarke transformation. Then, the α and β of the external rotor vector R1 are defined as α1 and β1, respectively, and the α and β of the internal rotor vector R2 are defined as α2 and β2, respectively. The error in α is calculated as α1 - α2 = αerr, and the error in β is calculated as β1 - β2 = βerr. Then, appropriate compensation is applied to the α error αerr and the β error βerr to calculate the manipulated variable rotor vector R3. When this manipulated variable rotor vector R3 is added to the internal rotor vector R2 and closed-loop feedback control is performed, the internal rotor vector R2 coincides with the external rotor vector R1.

[0079] FIG. 9 shows the vector locus of the manipulated variable rotor vector R3 in this closed-loop feedback control. In FIG. 9, the left diagram shows the vector locus of the manipulated variable rotor vector R3 when the external rotor vector R1 and the internal rotor vector R2 have the same frequency but different phases. In this case, the phases of the two vectors differ by 180°, and the maximum amplitude of the manipulated variable rotor vector R3 is twice the maximum amplitude of the external rotor vector R1 and the internal rotor vector R2. The right diagram shows the vector locus of the manipulated variable rotor vector R3 when the external rotor vector R1 and the internal rotor vector R2 have different frequencies and phases. In this case, the phases of the two vectors differ by 180°, and the maximum amplitude of the manipulated variable rotor vector R3 is twice the maximum amplitude of the external rotor vector R1 and the internal rotor vector R2. In this vector locus, a beat occurs due to the frequency component that is the difference between the frequency of the external rotor vector R1 and the frequency of the internal rotor vector R2.

[0080] However, in this method, addition is not performed on a vector but on the time axis, so this manipulated variable rotor vector R3 must be converted into a waveform. This transformation is called the inverse Clarke transform. Expressed mathematically, the inverse Clarke transform is given by the following determinant. This determinant is simply the reverse of the Clarke transform equation described above. The upper equation is called the "relative transform" or "amplitude invariant transform." The lower equation is called the "absolute transform" or "power invariant transform."

[0081]

number

[0082] [Operation] Next, the operation of the reference three-phase voltage signal generating device 100A configured as above will be described with reference to Figures 2, 7, and 8. Referring to Figures 2, 7, and 8, first, the reference three-phase voltage signal generating unit 2 adds the sinusoidal three-phase voltage control variable Oabcs to the internal three-phase voltage signal Vi from the internal three-phase voltage signal generator 1, and outputs the sinusoidal three-phase voltage signal Vrs obtained by this addition to the outside.

[0083] Next, the first Clarke transformer 3 transforms the sinusoidal reference three-phase voltage signal Vrs from the reference three-phase voltage signal generator 2 into a sinusoidal reference two-phase voltage signal Vrαβs in the αβ coordinate system using Clarke transformation. Meanwhile, the second Clarke transformer 5 transforms the external three-phase voltage signal Ve from the external voltage signal sensor unit 4 into a sinusoidal external two-phase voltage signal Veαβs in the αβ coordinate system using Clarke transformation. The sinusoidal reference two-phase voltage signal Vrαβs and the sinusoidal external two-phase voltage signal Veαβs respectively identify an external rotor vector R1 and an internal rotor vector R2. The external rotor vector R1 rotates at an angular velocity ω1 corresponding to the frequency of the external three-phase voltage signal Ve before Clarke transformation. The internal rotor vector R2 rotates at an angular velocity ω2 corresponding to the frequency of the internal three-phase voltage signal Vi or the sinusoidal reference three-phase voltage signal Vrs before Clarke transformation.

[0084] Next, the error generator 6 generates the error of the sinusoidal reference two-phase voltage signal Vrαβs relative to the sinusoidal external two-phase voltage signal Veαβs, thereby generating a sinusoidal two-phase voltage error signal Eαβs. Next, the compensator 7 applies compensation to the sinusoidal two-phase voltage error signal Eαβs to generate a sinusoidal two-phase voltage manipulated variable Oαβs. These processes correspond to the process of subtracting the internal rotor vector R2 from the external rotor vector R1 by vector calculation to obtain the manipulated variable rotor vector R3.

[0085] Next, the inverse Clarke transformation unit 8 transforms this sinusoidal wave two-phase voltage control amount Oαβs into a sinusoidal wave three-phase voltage control amount Oabcs in the abc coordinate system by inverse Clarke transformation.

[0086] Next, as described above, the reference three-phase voltage signal generator 2 adds the sinusoidal three-phase voltage control input Oabcs to the internal three-phase voltage signal Vi to generate the sinusoidal three-phase voltage reference signal Vrs. This process corresponds to adding the control input rotor vector R3 to the internal rotor vector R2 on the time axis.

[0087] Thereafter, the above-described closed loop process is repeated to perform feedback control of the sinusoidal wave reference three-phase voltage signal Vrs.

[0088] [simulation] To confirm the operation of the reference three-phase voltage signal generator 100A, a simulation was performed using the circuit configuration shown in Fig. 2. Fig. 10 is a waveform diagram showing the waveforms of signals at various parts in a simulation of the reference three-phase voltage signal generator 100A when the external three-phase voltage signal Ve and the internal three-phase voltage signal Vi differ only in phase. Fig. 11 is a waveform diagram showing the waveforms of signals at various parts in a simulation of the reference three-phase voltage signal generator 100A when the external three-phase voltage signal Ve and the internal three-phase voltage signal Vi differ in frequency.

[0089] 10 and 11, the first graph shows the waveform of the external three-phase voltage signal Ve, the second graph shows the waveform of the sinusoidal reference three-phase voltage signal Vrs, the third graph shows the waveform of the internal three-phase voltage signal Vi, and the fourth graph shows the waveform of the sinusoidal three-phase voltage control variable Oabcs. In each graph, the vertical axis represents amplitude and the horizontal axis represents time (ms). In each graph, the solid line represents the waveform of the U-phase signal, the dashed line represents the waveform of the V-phase signal, and the dashed-dotted line represents the waveform of the W-phase signal. Note that the vertical scale of the graph of the sinusoidal three-phase voltage control variable Oabcs in the fourth graph of FIG. 11 is twice that of the other graphs.

[0090] 10, this simulation was performed under the conditions that the external three-phase voltage signal Ve and the internal three-phase voltage signal Vi have the same frequency and that the phase of the internal three-phase voltage signal Vi lags behind the phase of the external three-phase voltage signal Ve by 45° at the start. The simulation results show that the sum of the internal three-phase voltage signal Vi and the sinusoidal three-phase voltage control amount Oabcs is the sinusoidal reference three-phase voltage signal Vrs, and that the external three-phase voltage signal Ve and the sinusoidal reference three-phase voltage signal Vrs are equal.

[0091] Referring to FIG. 11, this simulation was performed under the condition that the frequency of the external three-phase voltage signal Ve is 50 Hz and the frequency of the internal three-phase voltage signal Vi is 55 Hz. In this simulation result, the external three-phase voltage signal Ve is equal to the sinusoidal reference three-phase voltage signal Vrs. A beat component appears in the sinusoidal three-phase voltage control variable Oabcs. The sinusoidal three-phase voltage control variable Oabcs including this beat component has a waveform in which a sine wave signal with a frequency of 52.5 Hz fluctuates as a sine wave with a frequency of 5 Hz, and its amplitude is twice that of the external three-phase voltage signal Ve and the internal three-phase voltage signal Vi.

[0092] Thus, these simulations confirmed that the reference three-phase voltage signal generating device 100A can synchronize the internal three-phase voltage signal Vi with the external three-phase voltage signal Ve and output it as a sinusoidal reference three-phase voltage signal Vrs.

[0093] [effect] According to the second embodiment, the reference three-phase voltage signal generating device 100A can output a sine-wave reference three-phase voltage signal Vrs. Furthermore, the sine-wave reference three-phase voltage signal generating process (synchronization process) in the reference three-phase voltage signal generating device 100A is rate-determined by the sampling rate of the external three-phase voltage signal Ve. This sampling can be performed at, for example, 6 kHz. If the external three-phase voltage signal Ve is 50 Hz, there are 120 control chances (chances to acquire the external three-phase voltage signal Ve) in one cycle of the external three-phase voltage signal Ve. On the other hand, in the case of the zero-crossing point detection method, if the external three-phase voltage is 50 Hz, there are one or two control chances (chances to detect zero-crossing points) in one cycle of the external three-phase voltage signal. Therefore, according to the second embodiment, the speed of the process of generating the sine wave reference three-phase voltage signal is significantly faster than that of the conventional zero crossing point detection method, and as a result, the device that uses this sine wave reference three-phase voltage signal Vrs can respond quickly to abrupt fluctuations in the voltage of the external three-phase power wiring 10.

[0094] (Embodiment 3) In the reference three-phase voltage signal generator 100B according to the third embodiment, the second Clarke transformer 5 in the reference three-phase voltage signal generator 100 of the first embodiment applies the Clarke transform to the external three-phase voltage signal Ve and multiplies it by a rotation matrix with a 90° lead, so that the reference three-phase voltage signal generator 100B generates a cosine wave reference three-phase voltage signal Vrc.

[0095] Furthermore, comparing the reference three-phase voltage signal generator 100B according to the third embodiment with the reference three-phase voltage signal generator 100A according to the second embodiment, the reference three-phase voltage signal generator 100A differs in that the second Clarke transformer 5 only applies the Clarke transform to the external three-phase voltage signal V e , whereas the second Clarke transformer 5 in the reference three-phase voltage signal generator 100B applies the Clarke transform to the external three-phase voltage signal V e and multiplies it by a rotation matrix with a 90° lead. Therefore, the following mainly describes this difference. Regarding points not described below, please understand the contents by reading the second embodiment, replacing "sine wave" in the names of signals prefixed with "sine wave" with "cosine wave" and replacing the "s" at the end of the reference symbols with "c."

[0096] [Configuration and operation] FIG. 12 is a functional block diagram illustrating an example of the configuration of a reference three-phase voltage signal generating device according to the third embodiment of the present disclosure.

[0097] Referring to FIG. 12 , the reference three-phase voltage signal generating device 100B of the third embodiment includes an internal three-phase voltage signal generator 1, a reference three-phase voltage signal generating unit 2, a first Clarke transformer 3, an external voltage signal sensor unit 4, a second Clarke transformer 5, an error generating unit 6, a compensator 7, and an inverse Clarke transformer 8.

[0098] An internal three-phase voltage signal generator 1 generates an internal three-phase voltage signal Vi. A reference three-phase voltage signal generator 2 adds a cosine-wave three-phase voltage control variable Oabcc to the internal three-phase voltage signal Vi from the internal three-phase voltage signal generator 1, and outputs a cosine-wave reference three-phase voltage signal Vrc obtained by this addition to an external device. A first Clarke transformer 3 converts the cosine-wave reference three-phase voltage signal Vrc from the reference three-phase voltage signal generator 2 into a cosine-wave reference two-phase voltage signal Vrαβc in the αβ coordinate system by Clarke transformation. Meanwhile, an external voltage signal sensor unit 4 acquires an external three-phase voltage signal Ve from an external three-phase power wiring 10.

[0099] The second Clarke transformation unit 5 applies the Clarke transformation to the external three-phase voltage signal Ve from the external voltage signal sensor unit 4 and multiplies it by a rotation matrix with a 90° lead, thereby generating a cosine wave external two-phase voltage signal Veαβc in the αβ coordinate system.

[0100] A cosine wave has a phase lead of 90° compared to a sine wave. Therefore, multiplying the αβ of a sine wave by a rotation matrix with a 90° lead can convert it to a cosine wave αβ. The operation of multiplying the αβ of a sine wave by a rotation matrix with a 90° lead can be performed according to the following formula. As shown in the formula below, the α of a cosine wave is the -β of a sine wave, and the β of a cosine wave is the α of a sine wave.

[0101]

number

[0102] The error generating unit 6 generates a cosine-wave two-phase voltage error signal Eαβc by generating an error between the cosine-wave reference two-phase voltage signal Vrαβc from the first Clarke transformer 3 and the cosine-wave external two-phase voltage signal Veαβc from the second Clarke transformer 5. The compensating unit 7 generates a cosine-wave two-phase voltage control variable Oαβc by applying compensation to the cosine-wave two-phase voltage error signal Eαβc from the error generating unit 6. The inverse Clarke transformer 8 converts the cosine-wave two-phase voltage control variable Oαβc from the compensating unit 7 into a cosine-wave three-phase voltage control variable Oabcc in the abc coordinate system by inverse Clarke transform and inputs it to the reference three-phase voltage signal generating unit 2.

[0103] As described above, the reference three-phase voltage signal generator 2 adds the cosine-wave three-phase voltage control amount Oabcc to the internal three-phase voltage signal Vi to generate the cosine-wave reference three-phase voltage signal Vrc. Thereafter, the above-described closed-loop process is repeated to perform feedback control of the cosine-wave reference three-phase voltage signal Vrc.

[0104] In the third embodiment as well, it was confirmed by simulation that the reference three-phase voltage signal generating device 100B can generate and output a cosine wave reference three-phase voltage signal Vrc by causing the internal three-phase voltage signal Vi to have a phase lead of 90° relative to the external three-phase voltage signal Ve. The simulation results are similar to those under the same conditions, and therefore will not be described here.

[0105] [effect] According to the third embodiment, the reference three-phase voltage signal generator 100B can output the cosine wave reference three-phase voltage signal Vrc. Furthermore, the cosine wave reference three-phase voltage signal generation process (90° lead phase processing) in the reference three-phase voltage signal generator 100B is rate-limited by the sampling rate of the external three-phase voltage signal Ve. This sampling rate can be, for example, 6 kHz. If the external three-phase voltage signal Ve is 50 Hz, there are 120 control opportunities in one cycle of the external three-phase voltage signal Ve. On the other hand, with the zero-crossing point detection method, if the external three-phase voltage is 50 Hz, there are one or two control opportunities in one cycle of the external three-phase voltage signal. Therefore, according to the third embodiment, the speed of the cosine wave reference three-phase voltage signal generation process is significantly faster than with the conventional zero-crossing point detection method. As a result, devices using this cosine wave reference three-phase voltage signal Vrc can respond quickly to sudden fluctuations in the voltage of the external three-phase power wiring 10.

[0106] (Embodiment 4) A fourth embodiment of the present disclosure illustrates a reference three-phase voltage signal utilization device 1000A that uses only the sine wave reference three-phase voltage signal Vrs, which is the active component, as the reference three-phase voltage signal Vr.

[0107] FIG. 13A is a functional block diagram showing an example of the configuration of a reference three-phase voltage signal utilization device 1000A according to the fourth embodiment of the present disclosure.

[0108] 13A, a reference three-phase voltage signal utilization device 1000A includes the reference three-phase voltage signal generation device 100A of the second embodiment, a PWM signal generation circuit 201, and a three-phase inverter 202.

[0109] Examples of the reference three-phase voltage signal utilization device 1000A include grid-connected power supply devices such as UPS, CVCF (constant voltage constant frequency power supply), and PFC (high power factor converter). In the case of these grid-connected power supply devices, the power source to be synchronized is a commercial power supply (power supply system). Of course, the reference three-phase voltage signal utilization device 1000A may also be a power supply device that synchronizes the voltage of a general three-phase power supply (external three-phase power wiring) other than a commercial power supply.

[0110] The reference three-phase voltage signal generating device 100A outputs a sinusoidal reference three-phase voltage signal Vrs synchronized with the voltage of a predetermined three-phase power supply. The PWM signal generating circuit 201 generates and outputs a PWM signal corresponding to the sinusoidal reference three-phase voltage signal Vrs. The three-phase inverter 202 outputs a three-phase voltage Vout synchronized with the voltage of the predetermined three-phase power supply in accordance with the PWM signal.

[0111] Thus, according to the fourth embodiment, it is possible to provide a reference three-phase voltage signal utilization device that uses a sine wave reference three-phase voltage signal Vrs and that can respond quickly to abrupt fluctuations in the three-phase voltage of a predetermined three-phase power source that is the target of synchronization.

[0112] (Embodiment 5) A fifth embodiment of the present disclosure illustrates a reference three-phase voltage signal utilization device 1000B that uses, as the reference three-phase voltage signal Vr, a sine wave reference three-phase voltage signal Vrs that is an active component and a cosine wave reference three-phase voltage signal Vrc that is a reactive component.

[0113] FIG. 13B is a functional block diagram showing an example of the configuration of a reference three-phase voltage signal utilization device 1000B according to the fifth embodiment of the present disclosure.

[0114] Referring to FIG. 13B, a reference three-phase voltage signal utilization device 1000B includes the reference three-phase voltage signal generation device 100A of the second embodiment, the reference three-phase voltage signal generation device 100B of the third embodiment, a PWM signal generation circuit 201, and a three-phase inverter 202.

[0115] An example of the reference three-phase voltage signal utilization device 1000B is a PCS (power conditioner). In the case of this grid-connected power supply device, the power source is a commercial power source (power supply system). Of course, the reference three-phase voltage signal utilization device 1000B may also be a power supply device that synchronizes the voltage of a general three-phase power source (external three-phase power wiring) other than a commercial power source.

[0116] The reference three-phase voltage signal generating device 100A outputs a sine-wave reference three-phase voltage signal Vrs synchronized with the voltage of a predetermined three-phase power supply. The reference three-phase voltage signal generating device 100B outputs a cosine-wave reference three-phase voltage signal Vrc that leads the voltage of the predetermined three-phase power supply by 90°. The PWM signal generating circuit 201 generates and outputs PWM signals corresponding to the sine-wave reference three-phase voltage signal Vrs and the cosine-wave reference three-phase voltage signal Vrc. In response to the PWM signals, the three-phase inverter 202 outputs a three-phase voltage Vout that is synchronized with the voltage of the predetermined three-phase power supply and whose active power and reactive power are controlled.

[0117] Thus, according to the fifth embodiment, it is possible to provide a reference three-phase voltage signal utilization device that uses a sine wave reference three-phase voltage signal Vrs and a cosine wave reference three-phase voltage signal Vrc, and that is capable of quickly responding to abrupt fluctuations in the three-phase voltage of a predetermined three-phase power source that is the target of synchronization, etc.

[0118] 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]

[0119] The reference three-phase voltage signal generating device and reference three-phase voltage signal utilizing device of the present disclosure are useful as reference three-phase voltage signal generating devices and reference three-phase voltage signal utilizing devices that can respond quickly to abrupt fluctuations in the three-phase voltage of external three-phase power wiring that is the target of synchronization, etc. [Explanation of symbols]

[0120] 1 internal three-phase voltage signal generator 2. Reference three-phase voltage signal generator 3 Clark 1st Conversion Section 4 External voltage signal sensor unit 5 Clark 2nd Conversion Section 6 Error generator 7 Compensation Department 8 Inverse Clarke Transform 31 U-phase coil 32 V-phase coil 33 W-phase coil 100, 100A, 100B Reference Three-Phase Voltage Signal Generator 201 PWM signal generation circuit 202 Three-phase inverter Eαβ two-phase voltage error signal Eαβc Cosine wave two-phase voltage error signal Eαβs sinusoidal two-phase voltage error signal Ve external three-phase voltage signal Veu External U phase voltage signal Vev External V-phase voltage signal Vew External W phase voltage signal Veαβ External two-phase voltage signal Veαβc Cosine wave external two-phase voltage signal Veαβs Sinusoidal external two-phase voltage signal Vi internal three-phase voltage signal Viu Internal U phase voltage signal Viv Internal V phase voltage signal Viv Internal W phase voltage signal Vr Reference three-phase voltage signal Vrc cosine wave reference three-phase voltage signal Vrs Sine wave reference three-phase voltage signal Vru Reference U phase voltage signal Vrv Reference V-phase voltage signal Vrw Reference W phase voltage signal Vrαβ reference two-phase voltage control signal Vrαβc Cosine wave reference two-phase voltage operation signal Vrαβs Sine wave reference two-phase voltage control signal Oabc three-phase voltage operation amount Oabcs Sine wave three-phase voltage control variable Oabcc Cosine wave three-phase voltage control variable Oαβ Two-phase voltage control amount Oαβs Sine wave two-phase voltage control amount Oαβc Cosine wave two-phase voltage manipulated variable

Claims

1. An internal three-phase voltage signal generator that generates an internal three-phase voltage signal, A reference three-phase voltage signal generation unit adds a three-phase voltage manipulation amount to the internal three-phase voltage signal from the internal three-phase voltage signal generator and outputs the reference three-phase voltage signal obtained by the addition to the outside, A first Clark transform unit converts the reference three-phase voltage signal from the reference three-phase voltage signal generation unit into a reference two-phase voltage signal in the αβ coordinate system by a Clark transform, An external voltage signal sensor unit that acquires an external three-phase voltage signal from an external three-phase power wiring, A second Clark transform unit generates an external two-phase voltage signal in the αβ coordinate system by applying a Clark transform, or applying a Clark transform and multiplying it by a rotation matrix advanced by 90°, to the external three-phase voltage signal from the external voltage signal sensor unit. An error generation unit generates a two-phase voltage error signal by generating an error in the reference two-phase voltage signal from the first Clarke converter with respect to the external two-phase voltage signal from the second Clarke converter, A compensation unit that generates a two-phase voltage manipulation amount by applying compensation to the two-phase voltage error signal from the error generation unit, A reference three-phase voltage signal generating device comprising: an inverse Clarke transform unit that converts the two-phase voltage manipulation amount from the compensation unit into the three-phase voltage manipulation amount in the abc coordinate system by inverse Clarke transform, and inputs the three-phase voltage manipulation amount to the reference three-phase voltage signal generating unit.

2. The internal U-phase voltage signal, internal V-phase voltage signal, and internal W-phase voltage signal of the internal three-phase voltage signal are the internal a-voltage signal, internal b-voltage signal, and internal c-voltage signal in the abc coordinate system, respectively. The external U-phase voltage signal, external V-phase voltage signal, and external W-phase voltage signal of the external three-phase voltage signal are the external a-voltage signal, external b-voltage signal, and external c-voltage signal in the abc coordinate system, respectively. The reference three-phase voltage signal generation unit adds the a-voltage operation amount, b-voltage operation amount, and c-voltage operation amount of the three-phase voltage operation amount to the internal a-voltage signal, internal b-voltage signal, and internal c-voltage signal of the internal three-phase voltage signal from the internal three-phase voltage signal generator, and outputs the reference three-phase voltage signal to the outside, which includes the reference U-phase voltage signal (reference a-voltage signal), the reference V-phase voltage signal (reference b-voltage signal), and the reference W-phase voltage signal (reference c-voltage signal) obtained by the addition. The first Clarke transform unit is a transformer that converts the reference three-phase voltage signal, which includes the reference a voltage signal, the reference b voltage signal, and the reference c voltage signal from the reference three-phase voltage signal generation unit, into a reference two-phase voltage signal, which includes the reference α voltage signal and the reference β voltage signal in the αβ coordinate system, by Clarke transform. The second Clark transform unit is a transform unit that generates the external two-phase voltage signal including the external α voltage signal and external β voltage signal in the αβ coordinate system by applying a Clark transform, or applying a Clark transform and multiplying it by a rotation matrix advanced by 90°, to the external three-phase voltage signal including the external a voltage signal, the external b voltage signal, and the external c voltage signal from the external voltage signal sensor unit. The error generation unit is an error generation unit that generates a two-phase voltage error signal including an α voltage error signal and a β voltage error signal, which are the errors between the external α voltage signal and the external β voltage signal of the external two-phase voltage signal from the second Clarke converter and the reference α voltage signal and the reference β voltage signal of the reference two-phase voltage signal from the first Clarke converter, respectively. The compensation unit is a compensation unit that generates the two-phase voltage manipulation amount, including the α voltage manipulation amount and the β voltage manipulation amount, by applying compensation to the α voltage error signal and the β voltage error signal of the two-phase voltage error signal from the error generation unit, respectively. The reference three-phase voltage signal generating apparatus according to claim 1, wherein the inverse Clarke transform unit is a transformer that converts the two-phase voltage control amount, including the α voltage control amount and the β voltage control amount from the compensation unit, into a three-phase voltage control amount, including the a voltage control amount, the b voltage control amount, and the c voltage control amount in an abc coordinate system, by inverse Clarke transform, and inputs the said three-phase voltage control amount to the reference three-phase voltage signal generating unit.

3. The aforementioned reference three-phase voltage signal generation unit is a signal generation unit that adds a sinusoidal three-phase voltage manipulation amount to the internal three-phase voltage signal from the internal three-phase voltage signal generator and outputs the sinusoidal reference three-phase voltage signal obtained by the addition to the outside. The first Clark transform unit is a transformer that converts the sinusoidal reference three-phase voltage signal from the reference three-phase voltage signal generation unit into a sinusoidal reference two-phase voltage signal in the αβ coordinate system by Clark transform, The second Clark transform unit is a transform unit that generates a sinusoidal external two-phase voltage signal in the αβ coordinate system by applying a Clark transform to the external three-phase voltage signal from the external voltage signal sensor unit. The error generation unit is an error generation unit that generates a sinusoidal two-phase voltage error signal, which is the error between the sinusoidal reference two-phase voltage signal from the first Clarke transformer and the sinusoidal external two-phase voltage signal from the second Clarke transformer, The compensation unit is a compensation unit that generates a sinusoidal two-phase voltage manipulation amount by applying compensation to the sinusoidal two-phase voltage error signal from the error generation unit. The reference three-phase voltage signal generating apparatus according to claim 1, wherein the inverse Clarke transform unit is a transformer that converts the sinusoidal two-phase voltage manipulation amount from the compensation unit into the sinusoidal three-phase voltage manipulation amount in the abc coordinate system by inverse Clarke transform, and inputs the sinusoidal three-phase voltage manipulation amount to the reference three-phase voltage signal generating unit.

4. The aforementioned reference three-phase voltage signal generation unit is a signal generation unit that adds a cosine wave three-phase voltage manipulation amount to the internal three-phase voltage signal from the internal three-phase voltage signal generator and outputs the cosine wave reference three-phase voltage signal obtained by the addition to the outside. The first Clark transform unit is a transformer that converts the cosine wave reference three-phase voltage signal from the reference three-phase voltage signal generation unit into a cosine wave reference two-phase voltage signal in the αβ coordinate system by Clark transform, The second Clark transform unit is a transform unit that includes a Clark transform unit that generates a sinusoidal external two-phase voltage signal in an αβ coordinate system by applying a Clark transform to the external three-phase voltage signal from the external voltage signal sensor unit, and a rotation matrix multiplier unit that generates a cosine wave external two-phase voltage signal by multiplying the sinusoidal external two-phase voltage signal by a rotation matrix that advances by 90°, The error generation unit is an error generation unit that generates a cosine wave two-phase voltage error signal, which is the error between the cosine wave reference two-phase voltage signal from the first Clarke transform unit and the cosine wave external two-phase voltage signal from the rotation matrix multiplication unit of the second Clarke transform unit. The compensation unit is a compensation unit that generates a cosine wave two-phase voltage manipulation amount by applying compensation to the cosine wave two-phase voltage error signal from the error generation unit. The reference three-phase voltage signal generating apparatus according to claim 1, wherein the inverse Clarke transform unit is a transformer that converts the cosine wave two-phase voltage manipulation amount from the compensation unit into the cosine wave three-phase voltage manipulation amount in the abc coordinate system by inverse Clarke transform, and inputs the cosine wave three-phase voltage manipulation amount to the reference three-phase voltage signal generating unit.

5. The reference three-phase voltage signal generating apparatus according to claim 1, wherein the compensation unit is a compensation unit that applies PI compensation to the two-phase voltage error signal.

6. A reference three-phase voltage signal generating device according to any one of claims 1 to 5, A reference three-phase voltage signal utilization device comprising: a three-phase inverter that outputs a three-phase voltage synchronized with the three-phase voltage of the external three-phase power wiring by being PWM controlled in accordance with the reference three-phase voltage signal; and

7. The aforementioned reference three-phase voltage signal generation device is a device that outputs the reference three-phase voltage signal synchronized with the three-phase voltage of the power supply system as the external three-phase power wiring from the reference three-phase voltage signal generation unit. The reference three-phase voltage signal utilization device according to claim 6, wherein the three-phase inverter is PWM controlled in accordance with the reference three-phase voltage signal to output a three-phase voltage synchronized with the three-phase voltage of the power supply system.

Images