Power conversion system

Abstract

This power conversion system provides the ability to supply power according to output requirements without requiring software changes, even when repurposing existing power conversion equipment. [Solution] The power conversion system 1 comprises a power conversion device 3 and a control device 4. The power conversion device 3 has a three-phase full-bridge circuit 31 into which DC power is input, and has three legs 31u, 31v, and 31w connected in parallel between a high-potential side wiring 101 and a low-potential side wiring 102, and in one or two of these phases, the midpoint of the leg is connected to a power supply line 5 to a load 2 via a reactor. The control device 4 has a first control unit 41 that controls the switching operation of the power conversion device 3 by taking a pseudo-torque command signal based on an output command signal to the load 2 and a phase angle signal based on a detection signal of the supplied power as inputs, and a second control unit 42 that generates a pseudo-torque command signal and a phase angle signal and outputs them to the first control unit 41.

Description

[Technical Field]

[0001] The present invention relates to a power conversion system. [Background Art]

[0002] In a power supply system or a battery system for supplying power to stationary power consumption equipment, it is desired to supply power that meets system requirements with good controllability. For example, Patent Document 1 discloses that in a power supply system in which battery units each including a battery and a converter are connected in parallel, a problem of an increased load on a specific unit caused by power deviation resulting from sensor errors or control response delay is suppressed. For this purpose, a control device that performs voltage control of the converter for each unit is provided.

[0003] Further, Patent Document 1 proposes a system that reuses battery packs and control units in order to promote recycling and reuse of recovered products from vehicles. For example, the converter of each battery unit is a diverted power conversion device configured as a three-phase inverter, and a chopper circuit including each phase of the three-phase inverter is used as a converter corresponding to one battery pack, and is configured to perform control based on an output voltage command. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2024-52050 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] The power supply system described in Patent Document 1 includes a plurality of battery units, each of which is a converter using a phase of a three-phase inverter and connected to a battery pack. Each battery unit's converter is individually controlled by feeding back the unit's output voltage. In this case, for example, the control method set for a rotating machine cannot be used, and it was necessary to change the software for switching control of each phase.

[0006] This invention has been made in view of the above problems, and provides a power conversion system that can supply power according to output requirements without changing the software, even when existing power conversion devices are repurposed. [Means for solving the problem]

[0007] One aspect of the present invention is, A power conversion system (1) comprising a power converter (3) that converts power from a power source into power supplied to a stationary load (2), and a control device (4) that controls the power converter, The power converter is equipped with a three-phase full-bridge circuit (31) to which DC power is input. The three-phase full-bridge circuit has three legs (31u, 31v, 31w) connected in parallel between the high-potential side wiring (101) and the low-potential side wiring (102). Each of the three aforementioned legs consists of an upper arm switch (321u, 321v, 321w) and a lower arm switch (322u, 322v, 322w) connected in series. In one or two phases of the three-phase full-bridge circuit, the midpoint of the leg is connected to the power supply line (5) to the load via a reactor (33V, 33W). The control device is A first control unit (41) controls the switching operation of the power converter, taking a pseudo-torque command signal based on the output command signal to the load and a phase angle signal based on the detection signal of the supplied power as inputs. The power conversion system includes a second control unit (42) that generates the pseudo-torque command signal and the phase angle signal and outputs them to the first control unit. [Effects of the Invention]

[0008] In the power conversion system with the above configuration, the power converter converts the DC power input to one or two phases of a three-phase full-bridge circuit and outputs it to the power supply line to the load. The first control unit of the control device operates the power converter by using a pseudo-torque command signal, which is obtained by converting the output command signal to the load into torque representing the rotational force in rotational motion, and a phase angle signal, which is obtained by phase-shifting the detection signal of the supplied power. This makes it possible to repurpose power converters and control devices that perform control based on torque commands, for example.

[0009] As described above, according to the above embodiment, even when existing power conversion equipment is repurposed, a power conversion system can be provided that can supply power according to output requirements without requiring any software changes. The reference numerals in parentheses in the claims and the means for solving the problem indicate the correspondence with the specific means described in the embodiments later, and do not limit the technical scope of the present invention. [Brief explanation of the drawing]

[0010] [Figure 1] A circuit diagram showing the schematic configuration of the power conversion system in Embodiment 1. [Figure 2] A block diagram showing the configuration of the control device for the power conversion system in Embodiment 1. [Figure 3] A waveform diagram showing the relationship between three-phase current, duty cycle command, and gate command in Embodiment 1. [Figure 4] A block diagram showing the detailed configuration of the control device for the power conversion system in Embodiment 1. [Figure 5] A waveform diagram showing the relationship between the three-phase duty cycle command and the gate commands for the upper and lower arms of the V-phase in Embodiment 1. [Figure 6]A waveform diagram showing the relationship between three-phase current, phase angle, and resolver signals in Embodiment 1 [Figure 7] A circuit diagram showing the schematic configuration of a power conversion system in Embodiment 2. [Figure 8] A circuit diagram showing the schematic configuration of a power conversion system in Embodiment 3. [Figure 9] A circuit diagram showing the schematic configuration of a power conversion system in Embodiment 4. [Figure 10] A circuit diagram showing the schematic configuration of a power conversion system in Embodiment 5. DESCRIPTION OF EMBODIMENTS

[0011] (Embodiment 1) Hereinafter, Embodiment 1 related to a power conversion system will be described with reference to the drawings. As shown in FIG. 1, the power conversion system 1 of the present embodiment includes a power conversion device 3 that converts power supply power into power supplied to a stationary load 2, and a control device 4 that controls the power conversion device 3. The power conversion device 3 includes a three-phase full-bridge circuit 31 to which DC power is input. Here, a configuration is illustrated in which the power conversion device 3 includes one three-phase full-bridge circuit 31, and the power supply power is DC power from a DC power supply 11.

[0012] The three-phase full-bridge circuit 31 has three legs 31u, 31v, and 31w connected in parallel between a high-potential side wiring 101 and a low-potential side wiring 102. The three legs 31u, 31v, and 31w each are formed by connecting upper arm switches 321u, 321v, 321w and lower arm switches 322u, 322v, 322w in series. Each of the legs 31u, 31v, 31w corresponds to each of the three phases (U phase, V phase, W phase).

[0013] In the three-phase full-bridge circuit 31, one or two of the three phases is connected to the power supply line 5 for the load 2. Here, in two of the three phases (V phase and W phase), the midpoints of legs 31v and 31w are connected to the power supply line 5 via reactors 33v and 33w. The midpoints of legs 31v and 31w are the connection points of series-connected bodies composed of the corresponding upper arm switches 321v, 321w and lower arm switches 322v, 322w.

[0014] The control device 4 controls the three-phase full-bridge circuit 31 based on an output command for the load 2 and a detection signal of the power supplied to the load 2. Specifically, for the V-phase and W-phase legs 31v and 31w connected to the power supply line 5, the control device controls switching of the upper arm switches 321v, 321w and the lower arm switches 322v, 322w. As the detection signal of the supplied power, current signals Iv and Iw output from legs 31v and 31w, a current signal Idc on the power supply line 5, and the like are used.

[0015] As shown in Figure 2, the control device 4 includes a first control unit 41 and a second control unit 42. The first control unit 41 receives a pseudo torque command signal based on an output command signal to the load 2 and a phase angle signal based on a detection signal of power supplied to the load 2 as inputs, and controls the switching operation of the power conversion device 3. The second control unit 42 generates the pseudo torque command signal and the phase angle signal, and outputs the generated signals to the first control unit.

[0016] The second control unit 42 of the control device 4 converts the power output command signal to the load 2 into a rotational torque equivalent signal, which is a signal equivalent to rotational torque in rotational motion, using the detection signal of the supplied power, and can output the converted signal as the pseudo torque command signal. The second control unit 42 also calculates a phase angle signal based on the detection signal of the supplied power, converts the phase angle signal into a rotational angle equivalent signal, which is a signal equivalent to a rotational angle in rotational motion, and can output the converted signal as a pseudo rotational angle signal.

[0017] Furthermore, the first control unit 41 can generate switching command signals to control the switching of the upper arm switches 321v, 321w and the lower arm switches 322v, 322w based on the pseudo-torque command signal and the phase angle signal (or pseudo-rotation angle signal) input from the second control unit 42.

[0018] Specifically, the first control unit 41 of the control device 4 may include a first signal generation unit 41a, a second signal generation unit 41b, a third signal generation unit 41c, and a fourth signal generation unit 41d. The first signal generation unit 41a converts a pseudo-torque command signal into a voltage command signal. The second signal generation unit 41b converts a pseudo-rotation angle signal back into a phase angle signal. The third signal generation unit 41c generates a three-phase voltage command signal based on the converted voltage command signal and phase angle signal. The fourth signal generation unit 41d can generate a switching command signal based on the three-phase voltage command signal.

[0019] Furthermore, the second control unit 42 may include a first conversion unit 42a that converts an output command signal into a pseudo-torque command signal, and a second conversion unit 42b that converts a phase angle signal into a pseudo-rotation angle signal.

[0020] Here, the pseudo-torque command signal is an output command signal to the load 2 that is input as a signal that can be processed by the first control unit 41, and is a signal for commanding rotational torque in rotational motion, for example, a torque command that represents the rotational force required of a rotating machine. The first conversion unit 42a can convert the output command for power required to the load 2 (for example, a current command or a voltage command) into a rotational torque equivalent signal, which is a signal that corresponds to the rotational torque in rotational motion, by performing calculation processing using the detection signal of the power supplied to the load 2, and output it as a pseudo-torque command signal.

[0021] Furthermore, the pseudo-rotation angle signal corresponds to the rotational position signal in rotational motion, for example, the rotation angle in a rotating machine. When a rotation angle signal is required as an input signal to the first control unit 41, the phase angle signal can be further converted into a rotation angle equivalent signal, which is a signal corresponding to the rotation angle in rotational motion, and output. The second conversion unit 42b can convert a signal equivalent to a rotation angle signal by performing calculation processing using, for example, the phase signals (for example, current phase or voltage phase) of the power supplied from each phase of the power converter 3 to the load 2, and output it as a pseudo-rotation angle signal.

[0022] The first signal generation unit 41a can, for example, convert a pseudo-torque command signal into a current command signal in the dq coordinate system, and further convert it into a voltage command signal using a phase angle signal. In that case, the third signal generation unit 41c can convert this voltage command signal into a three-phase voltage command signal, and then the fourth signal generation unit 41d can convert it into switching command signals for each phase.

[0023] Based on this switching command signal, the three-phase full-bridge circuit 31 is switched and controlled, allowing the power converter 3 to output the required power and supply it to the load 2. In other words, the output power can be controlled by manipulating the pseudo-signals input from the second control unit 42 to the first control unit 41. For example, the waveform shape of the output current or output voltage can be arbitrarily controlled by a pseudo-rotation angle signal, and the magnitude of the output current or output voltage can be controlled by a pseudo-torque command signal.

[0024] The power supplied to load 2 can be, for example, DC power. In this case, the control device 4 can output DC power of a magnitude based on the output command signal to load 2 to the first control unit 41 by making the pseudo-rotation angle signal (phase angle signal) generated by the second control unit 42 a constant signal. The control device 4 has a microcomputer equipped with a processor, memory, etc., and its peripheral circuits. The control device 4 may be composed of multiple microcomputers and their peripheral devices.

[0025] Figure 3 shows, for example, the relationship between the switching command signal generated in the first control unit 41 of the control device 4 and the three-phase power waveform when the power converter 3 outputs DC power. The first control unit 41 converts the current of each phase of the three phases into a duty cycle command using the phase angle based on the detection signal so that it becomes the desired output waveform, generates a rectangular wave signal that becomes a gate command by comparing it with the carrier wave, and outputs it as a switching command signal.

[0026] In this case, a switching command signal can be generated so that the current output remains constant by utilizing a duty cycle corresponding to a specific phase angle. Furthermore, when using two of the three phases, as shown as the lock position in Figure 3, the output currents of the V and W phases can be controlled to be equal by using, for example, the phase angle at which the current waveforms of the V and W phases overlap.

[0027] This makes it possible to configure power conversion system 1, for example, by using a typical three-phase inverter and its control unit as is, without making any software changes. Details of the switching control by the control device 4 will be described later.

[0028] Next, specific application examples of the power conversion system 1 of this embodiment will be described. As shown in Figure 4, the power conversion system 1 of this embodiment can constitute part of a power supply system for supplying DC power to, for example, a stationary load 2, which is a power consuming equipment 21. The power source is, for example, the DC power source 11 shown in Figure 1, or it may be a storage battery or the like. The power conversion system 1 converts the power source from the DC power source 11 into DC power according to the power requirements of the power consuming equipment 21 in the power conversion device 3.

[0029] Examples of power-consuming equipment 21 include an electrolytic device that produces hydrogen by electrolyzing a raw material. The electrolytic device produces hydrogen by electrolyzing water vapor, which is the raw material gas, using electricity supplied by the power conversion system 1, and may, for example, have an SOEC (i.e., a Solid Oxide Electrolysis Cell). Alternatively, instead of power-consuming equipment 21, a power storage device may be provided as a load 2, and the power conversion device 3 may be used to charge the power storage device.

[0030] In Figure 1, the high-potential side wiring 101 and low-potential side wiring 102 of the power converter 3 are connected to the positive and negative terminals of the DC power supply 11, respectively. Between the DC power supply 11 and the three-phase full-bridge circuit 31, a DC link capacitor 34 is connected between the high-potential side wiring 101 and the low-potential side wiring 102. The midpoints of each leg 31u, 31v, and 31w of the three-phase full-bridge circuit 31 are connected to the output wirings 311u, 311v, and 311w, respectively. Of these, the output wiring 311u is idle wiring.

[0031] The output wires 311V and 311W are connected in parallel to the positive wire 5a of the power supply line 5 via reactors 33V and 33W, respectively. The positive wire 5a is connected to the positive terminal of load 2, and the negative wire 5b, which is connected to the negative terminal of load 2, is connected to the low-potential wire 102, which is the low-potential section of the power converter 3. A filter capacitor 35 is connected between the positive wire 5a and the negative wire 5b of the power supply line 5.

[0032] In the three-phase full-bridge circuit 31, the upper arm switches 321u, 321v, 321w and the lower arm switches 322u, 322v, 322w, which constitute the three legs 31u, 31v, and 31w, are, for example, IGBTs (isolated-gate bipolar transistors). Each IGBT has a freewheeling diode connected in reverse between its collector and emitter. The upper and lower arms may be composed of gate voltage-controlled semiconductor switching elements other than IGBTs, for example, MOSFETs (field-effect transistors) can be used.

[0033] Each of the legs 31u, 31v, and 31w has the collector side of the upper arm switches 321u, 321v, and 321 connected to the high-potential side wiring 101, and the emitter side of the lower arm switches 322u, 322v, and 322w connected to the low-potential side wiring 102. The low-potential side wiring 102 is set to, for example, ground potential.

[0034] The power conversion system 1 in this embodiment can be constructed, for example, by repurposing a power control unit (PCU) for electric vehicles. A typical vehicle PCU includes a three-phase inverter that supplies three-phase AC power to the motor and an inverter control device. The three-phase inverter can be used as the three-phase full-bridge circuit 31 of the power conversion device 3, and the inverter control device can be used as its control device 4.

[0035] In Figure 4, the control device 4 comprises a first control unit 41 corresponding to an inverter control device and a second control unit 42 that generates a pseudo-signal input to the first control unit 41. Generally, the inverter control device of a vehicle PCU is configured to detect the motor's electrical angle (≒current phase angle) using a resolver and to control each phase of a three-phase inverter based on the resolver signal fed back from the resolver and a torque command. Switching control of each phase is performed using pulse width modulation (PWM), and is configured to generate a gate command by calculating the on / off time ratio (duty cycle) of the upper and lower arms.

[0036] Therefore, in order to enable control of the power converter 3 without changing the control method such as the input signals to the first control unit 41 or their processing, the input signals to the first control unit 41 can be a pseudo-torque command signal corresponding to a torque command signal and a pseudo-resolver signal corresponding to a resolver signal. In addition, a second control unit 42 can be provided to convert the output command signal to the load 2 (e.g., DC current command) into a torque command signal and output it as a pseudo-torque command signal, and to convert the detection signals of the supplied power (e.g., Iv, Iw) into resolver signals and output them as pseudo-resolver signals. The resolver signal is a detection signal from a resolver that detects the rotation angle (i.e., a rotation angle signal), and the pseudo-resolver signal corresponds to a pseudo-rotation angle signal.

[0037] Specifically, the phase currents detected at the output wirings 311u, 311v, and 311w of the three-phase full-bridge circuit 31 are input to the first control unit 41, and the phase currents Iv and Iw of the two operating phases are input to the second control unit 42 (Figure 4 (1)). In the second control unit 42, the phase angle (unit: rad) is calculated in the second conversion unit 42b using the difference between the input phase currents Iv and Iw and a predetermined coefficient Kp (Figure 4 (2)). Furthermore, the phase angle signal is converted into a pseudo-resolver signal and output to the first control unit 41 (Figure 4 (3)).

[0038] Furthermore, the first conversion unit 42a of the second control unit 42 receives a DC current command signal based on the load 2's request, as well as a DC current signal Idc detected in the power supply line 5 to the load 2. The first conversion unit 42a converts the DC current command signal into a pseudo-torque command signal using PI control based on the difference with the detected DC current signal Idc and a predetermined MAP, and can output this to the first control unit 41.

[0039] In the first control unit 41, when a pseudo-resolver signal, which is a two-phase sin / cos signal, is input, the second signal generation unit 41b converts it back into a phase angle signal using an RD converter. Based on this phase angle signal, the three-phase (UVW) current input in (1) is converted into a d-axis current Id and a q-axis current Iq in the first signal generation unit 41a ((4) in Figure 4). If a general-purpose inverter without an RD converter is used, the conversion to a resolver signal and other processing may be omitted, and the phase angle signal may be directly input to the first control unit 41.

[0040] Furthermore, the first signal generation unit 41a converts the pseudo-torque command signal input from the second control unit 42 into a d-axis current command signal and a q-axis current command signal (5 in Figure 4). In addition, for the d-axis current command signal and the q-axis current command signal, the difference between them and the d-axis current Id and q-axis current Iq converted in (4) is calculated and converted into a d-axis voltage command signal and a q-axis voltage command signal by PI control (6 in Figure 4).

[0041] The third signal generation unit 41c further converts the dq-axis voltage command signal (6) into a three-phase voltage command signal Vc based on the phase angle signal converted by the first control unit 41 (7 in Figure 4). The third signal generation unit 41c receives the DC link voltage VH, which is the voltage across the DC link capacitor 34, from the power converter 3, and calculates the three-phase duty cycle command by dividing the three-phase voltage command Vc by VH / 2 (i.e., 2·Vc / VH) (8 in Figure 4). A gate command signal using the PWM method is generated from this three-phase duty cycle command and output to the power converter 3 (9 in Figure 4).

[0042] Figure 5 shows an example of control for supplying DC power to load 2 using two phases, V-phase and W-phase, illustrating the relationship between the three-phase duty cycle command signal (8) and the gate command signal (9) based on the three-phase duty cycle command signal. The gate command signal (9) is an example for the V-phase, and the other phases are omitted. At this time, the V-phase duty cycle command signal is converted into a square wave signal by comparison with the triangular wave of the carrier signal, and gate command signals are generated to command the on / off state of the upper arm switch 321v and the lower arm switch 322v, respectively.

[0043] As a result, each phase is switched and controlled at a predetermined duty cycle, and a gate command signal is repeatedly generated based on the output phase currents Iv and Iw and the target DC current command. Here, as described above (see Figure 3), the V-phase and W-phase outputs are controlled to be equal, so that the duty cycle command value of the V-phase gradually increases and the duty cycle command value of the W-phase gradually decreases, becoming equal in a short time from the start of control. After that, each phase is controlled with a constant duty cycle command value. Alternatively, the duty cycle command value may be increased or decreased by increasing or decreasing the pseudo-torque command signal in response to changes in the target DC current command value.

[0044] Figure 6 shows the relationship between the three-phase duty cycle command shown in Figure 5, the DC current command, and the three-phase current, along with the time evolution of the phase angle signal (2) and the resolver signal (3). It can be seen that the phase angle based on the phase currents Iv and Iw input to the second control unit 42 changes to follow the target DC current command, converges to a constant value, and the corresponding resolver signal changes. Furthermore, when the DC current command increases, the duty cycle command is controlled to increase at a certain phase angle, causing the phase currents Iv and Iw to increase, respectively.

[0045] In this way, the DC current output to the power supply line 5 quickly becomes the target DC current command, and it becomes possible to control it to quickly follow changes in the DC current command. Note that the phase current Iu of the U phase, which is not operated among the three phases, is approximately 0A.

[0046] Thus, according to this embodiment, by controlling the operation of the power converter 3, which includes a three-phase full-bridge circuit 31, with a control device 4 equipped with a first control unit 41 and a second control unit 42, the input DC power can be converted to any desired DC power and output. Furthermore, since general-purpose inverters and their control devices can be used for the power converter 3 and the first control unit 41, vehicle PCUs and the like can be reused and effectively utilized.

[0047] (Embodiment 2) Embodiment 2 of the power conversion system will be described with reference to Figure 7. As shown in the figure, the configuration of the power conversion device 3 in this embodiment of the power conversion system 1 differs from that of Embodiment 1. The other basic configurations are the same as those of Embodiment 1 and will not be described. In addition, among the reference numerals used in Embodiment 2 and later, those that are the same as those used in the previously described embodiments represent the same components, etc., as those in the previously described embodiments, unless otherwise specified.

[0048] In this configuration, only one of the three phases is connected to the load 2. Specifically, for the W phase of the three-phase full-bridge circuit 31, the output wiring 311w connected to the midpoint of leg 31w is connected to the power supply line 5 to the load 2 via reactor 33w. The output wirings 311u and 311v connected to the U phase and V phase legs 31u and 31v are idle wiring.

[0049] In this configuration as well, by performing similar control using the control device 4, the desired power can be supplied in response to the demands of the load 2. Furthermore, the same effects and advantages as in Embodiment 1 can be obtained.

[0050] (Embodiment 3) Embodiment 3 of the power conversion system will be described with reference to Figure 8. As shown in the figure, the power conversion system 1 of this embodiment differs from Embodiment 1 in its connection structure with the load 2.

[0051] In this embodiment, the power converter 3, similar to Embodiment 1 described above, connects the output wirings 311u and 311v of two of the three phases (here, the U phase and the V phase) of the three-phase full-bridge circuit 31 to the power supply line 5 to the load 2. One of the three phases (here, the W phase) is not operated, and its output wiring 311w is idle wiring.

[0052] In this configuration, the terminal of the idle output wiring 311w is connected to the negative wiring 5b of load 2. This ensures electrical connection without structural modifications, even if the power converter 3 does not have a ground terminal for external connections. Furthermore, the same effects and advantages as those of Embodiment 1 described above can be obtained.

[0053] (Embodiment 4) Embodiment 4 of the power conversion system will be described with reference to Figure 9. As shown in the figure, the power conversion system 1 of this embodiment differs from Embodiment 1 in the configuration of the power conversion device 3 and the connection structure with the load 2.

[0054] This embodiment is a power conversion system 1 in which the PCU used as a power conversion device 3 includes a first power conversion unit 3A configured as a converter in addition to a three-phase full-bridge circuit 31. The first power conversion unit 3A includes a leg 36 consisting of an upper arm switch 361 and a lower arm switch 362 between the three-phase full-bridge circuit 31 and the DC link capacitor 34. The upper arm switch 361 is connected to the high-potential side wiring 101 via a first wiring 363, and the lower arm switch 362 is connected to the low-potential side wiring 102 via a second wiring 364.

[0055] A reactor 366 is connected in series to the third wire 365, which is connected to the midpoint of leg 36, and a capacitor 367 is connected between the third wire 365 and the second wire 364. The capacitor 367 is located between the positive terminal for external connection of the third wire 365 and the reactor 366.

[0056] In this configuration, the first power conversion unit 3A does not perform power conversion, and the third wiring 365 is idle wiring. The second wiring 364, which is connected to the low-potential side potential line 102, is connected to the negative side wiring 5b of the load 2 via a negative side terminal provided at the opposite end.

[0057] Even in this manner, the negative wiring 5b of load 2 can be connected to the low-potential section of power converter 3 using the external connection terminal, thereby ensuring electrical connection without structural modifications. Furthermore, the same effects and advantages as those of Embodiment 1 described above can be obtained.

[0058] (Embodiment 5) Embodiment 5 of the power conversion system will be described with reference to Figure 10. As shown in the figure, the configuration of the power conversion device 3 in this embodiment of the power conversion system 1 differs from that of Embodiment 1.

[0059] This embodiment is a power conversion system 1 in which the PCU used as the power conversion device 3 includes a three-phase full-bridge circuit 31, as well as a second power conversion unit 3B which is configured as an inverter. Furthermore, the system is configured to use AC power from a three-phase AC power supply 11A as the power source, convert it to DC power in the power conversion device 3, and supply it to the load 2. The three-phase AC power supply 11A is, for example, a grid power supply.

[0060] In the power converter 3, the second power converter 3B is positioned between the three-phase AC power supply 11A and the DC link capacitor 34, and converts the input AC power into DC power. The second power converter 3B has a configuration similar to that of the three-phase full-bridge circuit 31 and has three legs 30u, 30v, and 30w connected in parallel between the high-potential side wiring 101 and the low-potential side wiring 102. The collector side of each leg 30u, 30v, and 30w is connected to the high-potential side wiring 101, and the emitter side of the lower arm switches 302u, 302v, and 302w is connected to the low-potential side wiring 102.

[0061] Each phase of the second power conversion unit 3B, specifically the midpoints of the legs 30u, 30v, and 30w, is connected to the three input wirings 12 of the three-phase AC power supply 11A via the reactor 13. The second power conversion unit 3B is switched and controlled by gate commands generated by the control device 4, similar to a normal inverter, and converts the three-phase AC power to DC power for output, charging the DC link capacitor 34. The configuration and operation of the three-phase full-bridge circuit 31 can be the same as in the embodiment 1 described above.

[0062] Thus, when the power supply is AC power, a second power conversion unit 3B can be provided between the three-phase AC power supply 11A and the three-phase full-bridge circuit 31 to convert the power supply to DC power and input it to the three-phase full-bridge circuit 31. In this way, the desired DC power can be supplied to the load 2. Furthermore, the same effects and advantages as in Embodiment 1 can be obtained.

[0063] In the configurations of Embodiments 3 to 5, it is also possible to operate only one phase of the three-phase full-bridge circuit 31, as in Embodiment 2. Furthermore, the connection position between the negative wiring 5b of the load 2 and the low-potential section of the power converter 3 can be changed as appropriate. In addition, the power converter 3 in the configurations shown in Embodiments 1 to 5 can be used as a basic unit, and multiple power converters 3 serving as basic units can be connected in parallel to the load 2 as a device.

[0064] The present invention is not limited to the embodiments described above, and can be applied to various embodiments without departing from its spirit. The following describes aspects of the present invention. [Section 1] A power conversion system (1) comprising a power converter (3) that converts power from a power source into power supplied to a stationary load (2), and a control device (4) that controls the power converter, The power converter is equipped with a three-phase full-bridge circuit (31) to which DC power is input. The three-phase full-bridge circuit has three legs (31u, 31v, 31w) connected in parallel between the high-potential side wiring (101) and the low-potential side wiring (102). Each of the three aforementioned legs consists of an upper arm switch (321u, 321v, 321w) and a lower arm switch (322u, 322v, 322w) connected in series. In one or two phases of the three-phase full-bridge circuit, the midpoint of the leg is connected to the power supply line (5) to the load via a reactor (33V, 33W). The control device is A first control unit (41) controls the switching operation of the power converter, taking a pseudo-torque command signal based on the output command signal to the load and a phase angle signal based on the detection signal of the supplied power as inputs. A power conversion system comprising: a second control unit (42) that generates the pseudo-torque command signal and the phase angle signal and outputs them to the first control unit. [Section 2] The power conversion system according to claim 1, wherein the second control unit converts the output command signal to the load into a rotational torque equivalent signal, which is a signal corresponding to the rotational torque in rotational motion, using the power supply detection signal, and outputs it as a pseudo-torque command signal. [Section 3] The power conversion system according to claim 2, wherein the second control unit calculates the phase angle signal based on the power supply detection signal, converts it into a rotation angle equivalent signal which is a signal corresponding to the rotation angle in rotational motion, and outputs it as a pseudo-rotation angle signal. [Section 4] The first control unit includes a first signal generation unit (41a) that converts the pseudo-torque command signal into a voltage command signal, a second signal generation unit (41b) that re-converts the pseudo-rotation angle signal into a phase angle signal, a third signal generation unit (41c) that generates a three-phase voltage command signal based on the voltage command signal and the phase angle signal, and a fourth signal generation unit (41d) that generates a switching command signal that controls the switching of the upper arm switch and the lower arm switch based on the three-phase voltage command signal and the phase angle signal. The power conversion system according to claim 3, wherein the second control unit includes a first conversion unit (42a) that converts the output command signal into the pseudo-torque command signal, and a second conversion unit (42b) that converts the phase angle signal into the pseudo-rotation angle signal. [Section 5] The power supplied to the aforementioned load is DC power. The power conversion system according to any one of items 1 to 4, wherein the second control unit outputs the phase angle signal as a constant signal to the first control unit. [Section 6] In two phases of the three-phase full-bridge circuit, the output wiring (311V, 311W) connected to the midpoint of the leg is connected to the power supply line. The power conversion system according to any one of claims 1 to 5, wherein the control device controls the switching operation of the power converter so that the output power from the legs corresponding to the two phases are equal. [Section 7] The power converter and the load are connected via the positive side wiring (5a) and negative side wiring (5b) of the power supply line. The power conversion system according to any one of items 1 to 6, wherein the negative wiring is connected to the low-potential portion of the power conversion device. [Section 8] The power conversion system according to paragraph 7, wherein the negative wiring is connected to the midpoint of one of the three legs of the three-phase full-bridge circuit that is not connected to the positive wiring. [Section 9] The aforementioned power converter further, Between the AC power supply (11A) and the three-phase full-bridge circuit, a DC link capacitor (34) is connected between the high-potential side wiring and the low-potential side wiring, The power conversion system according to any one of claims 1 to 8, comprising: a power conversion unit (3B) disposed between the AC power supply and the DC link capacitor, which converts AC power to DC power. [Explanation of Symbols]

[0065] 1. Power Conversion System 101 High-voltage side wiring 102 Low-voltage side wiring 2 loads 3. Power converter 31. Three-phase full-bridge circuit 31u, 31v, 31w Reg 4. Control device 41 First Control Unit 42 Second Control Unit 5 Power supply line

Claims

1. A power conversion system (1) comprising a power conversion device (3) that converts power from a power source into power supplied to a stationary load (2), and a control device (4) that controls the power conversion device, The power converter is equipped with a three-phase full-bridge circuit (31) to which DC power is input. The three-phase full-bridge circuit has three legs (31u, 31v, 31w) connected in parallel between the high-potential side wiring (101) and the low-potential side wiring (102). Each of the three aforementioned legs consists of an upper arm switch (321u, 321v, 321w) and a lower arm switch (322u, 322v, 322w) connected in series. In one or two phases of the three-phase full-bridge circuit, the midpoint of the leg is connected to the power supply line (5) to the load via a reactor (33V, 33W). The control device is A first control unit (41) controls the switching operation of the power converter, taking as input a pseudo-torque command signal based on the output command signal to the load and a phase angle signal based on the detection signal of the supplied power, A power conversion system comprising: a second control unit (42) that generates the pseudo-torque command signal and the phase angle signal and outputs them to the first control unit.

2. The power conversion system according to claim 1, wherein the second control unit converts the output command signal to the load into a rotational torque equivalent signal, which is a signal corresponding to the rotational torque in rotational motion, using the power supply detection signal, and outputs it as a pseudo-torque command signal.

3. The power conversion system according to claim 2, wherein the second control unit calculates the phase angle signal based on the power supply detection signal, converts it into a rotation angle equivalent signal which is a signal corresponding to the rotation angle in rotational motion, and outputs it as a pseudo-rotation angle signal.

4. The first control unit includes a first signal generation unit (41a) that converts the pseudo-torque command signal into a voltage command signal, a second signal generation unit (41b) that re-converts the pseudo-rotation angle signal into a phase angle signal, a third signal generation unit (41c) that generates a three-phase voltage command signal based on the voltage command signal and the phase angle signal, and a fourth signal generation unit (41d) that generates a switching command signal that controls the switching of the upper arm switch and the lower arm switch based on the three-phase voltage command signal and the phase angle signal. The power conversion system according to claim 3, wherein the second control unit comprises a first conversion unit (42a) that converts the output command signal into the pseudo-torque command signal, and a second conversion unit (42b) that converts the phase angle signal into the pseudo-rotation angle signal.

5. The power supplied to the aforementioned load is DC power. The power conversion system according to claim 1, wherein the second control unit outputs the phase angle signal as a constant signal to the first control unit.

6. In two phases of the three-phase full-bridge circuit, the output wiring (311V, 311W) connected to the midpoint of the leg is connected to the power supply line. The power conversion system according to claim 5, wherein the control device controls the switching operation of the power converter so that the output power to the output wiring corresponding to the two phases is equal.

7. The power converter and the load are connected via the positive side wiring (5a) and negative side wiring (5b) of the power supply line. The power conversion system according to any one of claims 1 to 6, wherein the negative wiring is connected to the low-potential section of the power conversion device.

8. The power conversion system according to claim 7, wherein the negative wiring is connected to the midpoint of one of the three legs of the three-phase full-bridge circuit that is not connected to the positive wiring.

9. The aforementioned power converter further, Between the AC power supply (11A) and the three-phase full-bridge circuit, a DC link capacitor (34) is connected between the high-potential side wiring and the low-potential side wiring, The power conversion system according to any one of claims 1 to 6, further comprising: a power conversion unit (3B) disposed between the AC power source and the DC link capacitor, which converts AC power to DC power.

Images