Power supply device and control method for power supply device

Abstract

To suppress generation of a circulating current with a simple configuration.SOLUTION: A power supply device includes a bidirectional converter having an input terminal electrically connected to an output terminal of a DC power supply, a bidirectional inverter having an input terminal electrically connected to an output terminal of the bidirectional converter, and a control device for controlling operation of the bidirectional converter and the bidirectional inverter. The control device performs control to add a virtual bidirectional diode circuit including a virtual bidirectional diode to the output terminal of the bidirectional converter.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a power supply device and a control method thereof.

Background Art

[0002] Patent Document 1 discloses a technique for suppressing the generation of a circulating current between a plurality of inverters when the plurality of inverters are operated in parallel. Patent Document 2 discloses a technique for suppressing the generation of a circulating current by adding a bidirectional switch circuit to the output terminal of an inverter so that only a unidirectional current flows.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technique described in Patent Document 1 suppresses circulating current by detecting the output current from an inverter and performing virtual impedance control in order to operate a plurality of inverters in parallel. In this case, when a unidirectional converter is connected to the input terminal of the inverter, since the input voltage to one of the inverters becomes a charging operation to the DC voltage side due to the flowing of the circulating current and increases, by detecting the increased input voltage, control can be performed to suppress the generation of the circulating current. However, when the output terminal of a bidirectional converter is connected to the input terminal of the inverter or the like, the input voltage to the inverter does not increase due to the result of the constant voltage control of the bidirectional converter, so there is a possibility that the inverter cannot suppress the generation of the circulating current. For example, although the technique disclosed in Patent Document 2 can suppress the generation of the circulating current, since it is necessary to add a circuit for suppressing the generation of the circulating current, there is a possibility that the cost increases or the power loss increases.

[0005] An object of the present disclosure is to suppress the generation of a circulating current with a simple configuration.

Means for Solving the Problems

[0006] A power supply device according to one aspect of the present disclosure includes a bidirectional converter whose input terminal is electrically connected to the output terminal of a DC power supply, a bidirectional inverter whose input terminal is electrically connected to the output terminal of the bidirectional converter, and a control device that controls the operations of the bidirectional converter and the bidirectional inverter, and the control device performs control to add a virtual bidirectional diode circuit including a virtual bidirectional diode to the output terminal of the bidirectional converter.

[0007] In the power supply device of the present disclosure, the control device detects the DC voltage input from the bidirectional converter to the bidirectional inverter, and when the DC voltage rises by a predetermined amount or more, changes the current output command value of the bidirectional inverter in the positive direction.

[0008] In the power supply device of the present disclosure, it includes a plurality of the bidirectional converters and a plurality of the bidirectional inverters. The input terminals of the plurality of bidirectional converters are each connected in parallel to the output terminal of the DC power supply. The output terminals of the plurality of bidirectional converters are each connected to the input terminals of the corresponding plurality of bidirectional inverters. The output terminals of the plurality of bidirectional inverters are each connected in parallel.

[0009] In the power supply device of the present disclosure, it includes a plurality of the DC power supplies, a plurality of the bidirectional converters, and a plurality of the bidirectional inverters. The output terminals of the plurality of DC power supplies are each connected to the input terminals of the corresponding plurality of bidirectional converters. The output terminals of the plurality of bidirectional converters are each connected to the input terminals of the corresponding plurality of bidirectional inverters. The output terminals of the plurality of bidirectional inverters are each connected in parallel.

[0010] In the power supply device of the present disclosure, it includes an AC power supply to which the output terminals of each of the plurality of bidirectional inverters are connected to the output terminal. The output terminals of the bidirectional inverters and the output terminal of the AC power supply are connected in parallel. The control device controls the AC voltage between the output terminals of the bidirectional inverters connected in parallel and the output terminal of the AC power supply to charge the DC power supply.

[0011] In the power supply device of the present disclosure, when the AC voltage rises above a predetermined value, the current command value of the bidirectional inverter is changed in the minus direction.

[0012] In the power supply device of the present disclosure, the control device detects the DC current output from the bidirectional converter and controls the virtual bidirectional diode based on the DC current output from the bidirectional converter.

[0013] In the power supply device of the present disclosure, the control device adds a virtual bidirectional diode circuit including a virtual bidirectional diode to the output terminal of the bidirectional converter, and controls to increase or decrease the output voltage of the bidirectional converter when the direction of the current flowing through the bidirectional converter changes.

[0014] A control method for a power supply device according to an aspect of the present disclosure is a control method for a power supply device including a bidirectional converter whose input terminal is electrically connected to the output terminal of a DC power supply, a bidirectional inverter whose input terminal is electrically connected to the output terminal of the bidirectional converter, and a control device that controls the operations of the bidirectional converter and the bidirectional inverter. The control device performs control to add a virtual bidirectional diode circuit including a virtual bidirectional diode to the output terminal of the bidirectional converter.

Advantages of the Invention

[0015] According to the present disclosure, generation of a circulating current can be suppressed with a simple configuration.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. Note that the present disclosure is not limited by this embodiment, and in the following embodiments, the same parts are denoted by the same reference numerals to omit redundant descriptions.

[0018] [Power Supply Device] A configuration example of the power supply device according to the embodiment will be described with reference to FIG. 1. FIG. 1 is a diagram showing a configuration example of the power supply device according to the embodiment.

[0019] As shown in FIG. 1, the power supply device 1000 includes power supply devices 1100-1 to 1100-n (n is an integer of 2 or more). The power supply devices 1100-1 to 1100-n are connected in parallel to each other. The power supply devices 1100-1 to 1100-n each include a converter 100-1 to 100-n, an inverter 200-1 to 200-n, a control device 300-1 to 300-n, and a virtual bidirectional diode circuit 400-1 to 400-n.

[0020] Converters 100-1 to 100-n are bidirectional converters. Converters 100-1 to 100n are connected in parallel respectively. The input terminals of converters 100-1 to 100-n are electrically connected to the output terminals of DC power supply 1. Converters 100-1 to 100-n each receive DC current i bat1 from DC current i batn from DC power supply 1. Converters 100-1 to 100-n each output DC current i dc1 to DC current i dcn from their output terminals. When there is no need to particularly distinguish between converters 100-1 to 100-n, they may also be collectively referred to as converter 100.

[0021] Inverters 200-1 to 200-n are bidirectional inverters. Inverters 200-1 to 200-n are connected in parallel. The input terminals of inverters 200-1 to 200-n are each electrically connected to the output terminals of converters 100-1 to 100-n via virtual bidirectional diode circuits 400-1 to 400-n. Inverters 200-1 to 200-n each receive DC voltage V dc1 from DC voltage V dcn output by virtual bidirectional diode circuits 400-1 to 400-n. The output terminals of inverters 200-1 to 200-n are electrically connected to the input terminals of the load. Inverters 200-1 to 200-n each output AC current i o1 to AC current i on from their output terminals. As a result, AC voltage V ac is applied to load 2. When there is no need to particularly distinguish between inverters 200-1 to 200-n, they may also be collectively referred to as inverter 200.

[0022] The control devices 300-1 to 300-n respectively control the operations of the converters 100-1 to 100-n and the inverters 200-1 to 200-n. When there is no need to particularly distinguish the control devices 300-1 to 300-n, they may also be collectively referred to as the control device 300. The control device 300 includes, for example, an information processing device such as a DSP (Digital Signal Processor) with a built-in digital PWM (Pulse Width Modulation) circuit, a CPU (Central Processing Unit), or an MPU (Micro Processing Unit), and a storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory). The control device 300 may be realized by, for example, an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The control device 300 may also be realized by a combination of hardware and software.

[0023] The control devices 300-1 to 300-n respectively perform control to add virtual bidirectional diode circuits 400-1 to 400-n to the output terminals of the converters 100-1 to 100-n, respectively. When there is no need to particularly distinguish the virtual bidirectional diode circuits 400-1 to 400-n, they may also be collectively referred to as the virtual bidirectional diode circuit 400.

[0024] The virtual bidirectional diode circuit 400 is a virtual circuit in which the input terminal is considered to be connected to the output terminal of the converter 100, and the output terminal is considered to be connected to the input terminal of the inverter 200.

[0025] The virtual bidirectional diode circuit 400 includes a virtual diode D1, a virtual diode D2, and a virtual resistor R1. The virtual diode D1, the virtual diode D2, and the virtual resistor R1 are virtual elements.

[0026] One end of the anode of the virtual diode D1, the cathode of the virtual diode D2, and one end of the virtual resistor R1 is electrically connected to the output terminal of the converter 100. One end of the cathode of the virtual diode D1, the anode of the virtual diode D2, and the virtual resistor R1 is electrically connected to the input terminal of the inverter 200.

[0027] The virtual diode D1, the virtual diode D2, and the virtual resistor R1 have functions as a bidirectional diode. The control device 300 controls the virtual bidirectional diode circuit 400 to prevent the reverse flow of current between the converter 100 and the inverter 200, thereby suppressing the generation of circulating current.

[0028] (Configuration example of the converter) (First example) Using FIG. 2, a configuration example of the converter according to the first example according to the embodiment will be described. FIG. 2 is a diagram showing a configuration example of the converter according to the first example according to the embodiment. As shown in FIG. 2, the converter 100 according to the first example of the embodiment is a bidirectional chopper circuit. The converter 100 receives the output voltage V1 output from the primary DC power supply 1 and smoothed by the capacitor 3, and outputs the output voltage V2 to the secondary load 2.

[0029] One end of the capacitor 3 is electrically connected to the high potential side of the DC power supply 1. The other end of the capacitor 3 is electrically connected to the low potential side.

[0030] The converter 100 includes a bridge circuit 110 and a reactor 20.

[0031] The bridge circuit 110 includes a transistor 11 and a transistor 12. The transistor 11 is a transistor controlled during step - down. The transistor 12 is a transistor controlled during step - up. The transistor 11 and the transistor 12 are controlled to be turned on and off by a control device 300. The control device 300 can seamlessly change the step - up operation and the step - down operation by alternately turning on and off the transistor 11 and the transistor 12.

[0032] In the embodiment, each transistor is assumed to be a MOSFET, but the present disclosure is not limited thereto. Each transistor may be a silicon power device, a GaN power device, a SiC power device (e.g., IGBT (Insulated Gate Bipolar Transistor)), etc.

[0033] Each transistor has a parasitic diode (body diode) that can actively conduct current, or a diode is connected in anti - parallel. The parasitic diode is a pn junction between the back gate of the MOSFET and the source and drain.

[0034] The drain of the transistor 11 is electrically connected to the high - potential side of the load 2. The source of the transistor 11 is electrically connected to the drain of the transistor 12. The source of the transistor 12 is electrically connected to the low - potential side of the DC power supply 1 and the low - potential side of the load 2.

[0035] One end of the reactor 20 is electrically connected to one end of the capacitor 3. The other end of the reactor 20 is electrically connected to the source of the transistor 11 and the drain of the transistor 12.

[0036] The voltage of the capacitor 4 is the output voltage V2. One end of the capacitor 4 is electrically connected to the high - potential side of the load 2. The other end of the capacitor 4 is electrically connected to the low - potential side of the load 2.

[0037] (Second example) With reference to FIG. 3, a configuration example of a converter according to a second example of the embodiment will be described. FIG. 3 is a diagram showing a configuration example of a converter according to a second example of the embodiment. The converter 100A according to the second example of the embodiment is of the DAB (Dual Active Bridge) type and is a bidirectional DC-DC converter. The converter 100A receives the output voltage V1 output from the primary DC power supply 1 and smoothed by the capacitor 3, and outputs the output voltage V2 to the secondary load 2.

[0038] The converter 100A includes a first bridge circuit 110A, a reactor 21, a transformer 22, and a second bridge circuit 120A.

[0039] The first bridge circuit 110A is a single-phase full-bridge circuit including a first arm 31 and a second arm 32. The first arm 31 includes transistors 11 and 12. The second arm 32 includes transistors 13 and 14. The on and off states of transistors 11 to 14 are controlled by the control device 300.

[0040] The source of transistor 11 is electrically connected to the drain of transistor 12. The drain of transistor 11 is electrically connected to the drain of transistor 13. The source of transistor 13 is electrically connected to the drain of transistor 14. The source of transistor 12 is electrically connected to the source of transistor 14.

[0041] The drains of transistor 11 and transistor 13 are electrically connected to the high-potential side of the DC power supply 1. The sources of transistor 12 and transistor 14 are electrically connected to the low-potential side of the DC power supply 1.

[0042] The source of transistor 11 and the drain of transistor 12 are electrically connected to one output terminal 10a of the first bridge circuit 110A. The source of transistor 13 and the drain of transistor 14 are electrically connected to the other output terminal 10b of the first bridge circuit 110A.

[0043] The second bridge circuit 120A is a single-phase full-bridge circuit including a first arm 41 and a second arm 42. The first arm 41 includes transistors 51 and 52. The second arm 42 includes transistors 53 and 54. Transistors 51 to 54 are controlled to be turned on and off by the control device 300.

[0044] The source of transistor 51 is electrically connected to the drain of transistor 52. The drain of transistor 51 is electrically connected to the drain of transistor 53. The source of transistor 53 is electrically connected to the drain of transistor 54. The source of transistor 52 is electrically connected to the source of transistor 54.

[0045] The drains of transistors 51 and 53 are electrically connected to the high potential side of load 2. The sources of transistors 52 and 54 are electrically connected to the low potential side of load 2.

[0046] The source of transistor 51 and the drain of transistor 52 are electrically connected to one output terminal 20a of the second bridge circuit 120A. The source of transistor 53 and the drain of transistor 54 are electrically connected to the other output terminal 20b of the second bridge circuit 120A.

[0047] One end of the reactor 21 is electrically connected to the output terminal 20a. Although the reactor 21 is arranged on the secondary side, the present disclosure is not limited thereto. The reactor 21 may be arranged on the primary side or on both the primary side and the secondary side.

[0048] The transformer 22 includes a first winding 22a, a second winding 22b, and a core 22c. The first winding 22a and the second winding 22b are wound around the core 22c.

[0049] The winding ratio of the first winding 22a to the second winding 22b is exemplified by 1:1, but the present disclosure is not limited thereto.

[0050] One end of the first winding 22a is electrically connected to the output terminal 10a. The other end of the first winding 22a is electrically connected to the output terminal 10b.

[0051] One end of the second winding 22b is electrically connected to the other end of the reactor 21. The other end of the second winding 22b is electrically connected to the output terminal 20b.

[0052] (Inverter) Using FIG. 4, a configuration example of the inverter according to the embodiment will be described. FIG. 4 is a diagram showing a configuration example of the inverter according to the embodiment.

[0053] As shown in FIG. 4, the inverter 200 includes a first arm 71, a second arm 72, a third arm 73, reactors 74, 75, 76, capacitors 77, 78, 79, a voltage detector 80, a voltage detector 81, a current detector 82, and a current detector 83. The inverter 200 is, for example, a three-phase inverter.

[0054] The first arm 71, the second arm 72, and the third arm 73 constitute a bridge circuit 70. The first arm 71 is the U-phase arm. The second arm 72 is the V-phase arm. The third arm 73 is the W-phase arm. The phase difference between the first arm 71 and the second arm 72 is 120 degrees. The phase difference between the second arm 72 and the third arm 73 is 120 degrees. The phase difference between the third arm 73 and the first arm 71 is 120 degrees.

[0055] The first arm 71 includes a transistor 91 and a transistor 92. The transistor 91 and the transistor 92 are controlled to be turned on and off by the control device 300.

[0056] The drain of the transistor 91 is electrically connected to one output terminal of the converter 100. The source of the transistor 91 is electrically connected to the drain of the transistor 92. The source of the transistor 92 is electrically connected to the other output terminal of the converter 100.

[0057] The second arm 72 includes a transistor 93 and a transistor 94. The transistor 93 and the transistor 94 are controlled to be turned on and off by the control device 300.

[0058] The drain of the transistor 93 is electrically connected to one output terminal of the converter 100. The source of the transistor 93 is electrically connected to the drain of the transistor 94. The source of the transistor 94 is electrically connected to the other output terminal of the converter 100.

[0059] The third arm 73 includes a transistor 95 and a transistor 96. The transistor 95 and the transistor 96 are controlled to be turned on and off by the control device 300.

[0060] The drain of the transistor 95 is electrically connected to one output terminal of the converter 100. The source of the transistor 95 is electrically connected to the drain of the transistor 96. The source of the transistor 96 is electrically connected to the other output terminal of the converter 100.

[0061] One end of the reactor 74 is electrically connected to the source of the transistor 91 and the drain of the transistor 92. The other end of the reactor 74 is electrically connected to one end of the capacitor 77, one end of the capacitor 78, and one end of the current detector 82.

[0062] One end of the reactor 75 is electrically connected to the source of the transistor 93 and the drain of the transistor 94. The other end of the reactor 75 is electrically connected to the other end of the capacitor 77, one end of the capacitor 79, and the load.

[0063] One end of the reactor 76 is electrically connected to the source of the transistor 95 and the drain of the transistor 96. The other end of the reactor 76 is electrically connected to the other end of the capacitor 78, the other end of the capacitor 79, and one end of the current detector 83.

[0064] The voltage detector 80 detects the voltage between the U phase and the V phase. The voltage detector 81 detects the voltage between the V phase and the W phase. The voltage detectors 80 and 81 output the voltage detection results to the control device 300.

[0065] The other end of the current detector 82 is electrically connected to the load 2. The current detector 82 detects the current i1 flowing from the connection point of the source of the transistor 91 and the drain of the transistor 92 to the load 2. The other end of the current detector 83 is electrically connected to the load 2. The current detector 83 detects the current i2 flowing from the connection point of the source of the transistor 95 and the drain of the transistor 96 to the load 2. The current detectors 82 and 83 respectively output the detection results of the current i1 and the current i2 to the control device 300.

[0066] (Control device) Using FIG. 5, a configuration example of the control device according to the embodiment will be described. FIG. 5 is a block diagram showing a configuration example of the control device according to the embodiment.

[0067] As shown in FIG. 5, the control device 300 includes a converter control unit 310 and an inverter control unit 320.

[0068] The converter control unit 310 controls the converter 100. The inverter control unit 320 controls the inverter 200. With such a configuration, the control device 300 can control the converter 100 and the inverter 200.

[0069] (Converter control unit) Using FIG. 6, a configuration example of the converter control unit according to the first example of the embodiment will be described. FIG. 6 is a diagram showing a configuration example of the converter control unit according to the first example of the embodiment.

[0070] As shown in FIG. 6, the converter control unit 310 includes a parallel operation control unit 301, a subtraction unit 302, a feedback control unit 303, a drive pulse generation unit 304, and a pulse drive unit 305.

[0071] The parallel operation control unit 301 executes a process of adding to the virtual bidirectional diode circuit 400 at the output terminal of the converter 100. The parallel operation control unit 301 includes a low-pass filter 311, a virtual bidirectional diode control unit 312, and a subtraction unit 313.

[0072] The low-pass filter 311 receives the direct current i output by the converter 100 dc . The low-pass filter 311 may receive the direct current i input from the DC power supply 1 to the converter 100 bat . The low-pass filter 311 removes the high-frequency components of the direct current i dc or the direct current i bat and outputs the direct current i lpf to the virtual bidirectional diode control unit 312.

[0073] The virtual bidirectional diode control unit 312 controls the virtual bidirectional diode circuit 400. The virtual bidirectional diode control unit 312 calculates the voltage value that may occur in the virtual bidirectional diode circuit 400 based on the direct current i lpf received from the low-pass filter 311. The virtual bidirectional diode control unit 312 outputs a voltage signal V bid indicating the calculated voltage value to the subtraction unit 313.

[0074] The subtraction unit 313 receives the voltage command value V ref and the voltage signal V bid The subtraction unit 313 receives the voltage command value V ref and subtracts the voltage signal V bid from it. The subtraction unit 313 outputs a signal S11 indicating the difference between the voltage command value V ref and the voltage signal V bid to the subtraction unit 302.

[0075] The subtraction unit 302 receives the signal S11 and the output voltage V2 of the converter 100. The subtraction unit 302 subtracts the output voltage V2 from the signal S11. The subtraction unit 302 outputs a signal S12 indicating the difference between the signal S11 and the output voltage V2 to the feedback control unit 303.

[0076] The feedback control unit 303 receives the signal S12. The feedback control unit 303 performs feedback control based on the signal S12. The feedback control unit 303 calculates the duty ratio based on the signal S12. The feedback control unit 303 calculates the duty ratio by executing, for example, a PID (Proportional Integral Derivative) operation. The feedback control unit 303 outputs a duty ratio command signal S13 indicating the calculated duty ratio to the drive pulse generation unit 304.

[0077] The drive pulse generation unit 304 receives the duty ratio command signal S13. The drive pulse generation unit 304 outputs a pulse signal S14 including pulses input to the transistors 11 and 12 to the pulse drive unit 305 based on the duty ratio command signal S13.

[0078] The pulse drive unit 305 receives the pulse signal S14. The pulse drive unit 305 changes the voltage level of the pulse signal S14 and generates a drive pulse S15 for switching the on and off states of the transistors 11 and 12. The pulse drive unit 305 outputs the drive pulse S15 to the gates of the transistors 11 and 12.

[0079] (Output Voltage Characteristics) Using FIG. 7, the output voltage characteristics of the converter according to the embodiment will be described. FIG. 7 is a diagram showing the output voltage characteristics of the converter according to the embodiment. In FIG. 7, the horizontal axis represents the direct current i bat input to the converter 100, and the vertical axis represents the output voltage V dc output from the converter 100.

[0080] As shown in FIG. 7, the converter control unit 310 adds a virtual bidirectional diode circuit 400 to the output terminal of the converter 100, so that when the direction of the current flowing through the converter 100 changes, the output voltage V dc of the converter 100 is increased or decreased. Specifically, when the converter 100 is in the discharging operation, that is, when the direction of the current flow becomes positive, the converter control unit 310 decreases the output voltage V dc . Also, when the converter 100 is in the charging operation, that is, when the direction of the current flow becomes negative, the converter control unit 310 increases the output voltage V dc . As a result, when the converter 100 is in the charging operation, the voltage input to the inverter 200 increases. When the converter control unit 310 detects an increase in the voltage input to the inverter 200, it can suppress the generation of the circulating current by changing the effective current component of the inverter 200 in the discharging direction. The control of the inverter 200 will be described later.

[0081] (Processing Contents) Using FIG. 8, the processing contents of the converter control unit according to the embodiment will be described. FIG. 8 is a flowchart showing the processing contents of the converter control unit according to the embodiment.

[0082] The converter control unit 310 sets an initial value of the output voltage of the virtual bidirectional diode circuit 400 (step S101). Then, it proceeds to step S102.

[0083] The converter control unit 310 determines whether the output voltage of the virtual bidirectional diode circuit 400 is in the discharge direction and exceeds a first threshold value (step S102). The first threshold value may be arbitrarily set according to the design. If it is determined that the voltage is in the discharge direction and exceeds the first threshold value (step S102; Yes), the process proceeds to step S103. If it is determined that the output voltage is not in the discharge direction and does not exceed the first threshold value (step S102; No), the process proceeds to step S104.

[0084] When it is determined as Yes in step S102, the converter control unit 310 sets the output voltage of the virtual bidirectional diode circuit 400 to the first threshold value (step S103). Specifically, the converter control unit 310 controls the characteristics of the virtual diode D1, the virtual diode D2, and the virtual resistor R1 included in the virtual bidirectional diode circuit 400 to set the output voltage of the virtual bidirectional diode circuit 400 to the first threshold value. Then, the process of FIG. 8 ends.

[0085] When it is determined as No in step S102, the converter control unit 310 determines whether the output voltage of the virtual bidirectional diode circuit 400 is in the charging direction and less than a second threshold value (step S104). The second threshold value may be set according to the design. If it is determined that the output voltage is in the charging direction and less than the second threshold value (step S104; Yes), the process proceeds to step S105. If it is determined that the output voltage is not in the charging direction and does not less than the second threshold value (step S104; No), the process proceeds to step S106.

[0086] When it is determined as Yes in step S104, the converter control unit 310 sets the output voltage of the virtual bidirectional diode circuit 400 to the second threshold value (step S105). Then, the process of FIG. 8 ends.

[0087] When it is determined as No in step S104, the converter control unit 310 sets the output voltage of the virtual bidirectional diode circuit 400 to the initial value (step S106). Then, the process of FIG. 6 ends.

[0088] (Configuration Example of Converter Control Unit in the Second Example) With reference to FIG. 9, a configuration example of a converter control unit according to a second example of the embodiment will be described. FIG. 9 is a diagram showing a configuration example of a converter control unit according to a second example of the embodiment.

[0089] As shown in FIG. 9, the converter control unit 310A includes a parallel operation control unit 301, a subtraction unit 302, a feedback control unit 303A, a drive pulse generation unit 304A, a primary side pulse drive unit 306, and a secondary side pulse drive unit 307. The converter control unit 310A is a control device that controls the converter 100A when the power supply device 1000 includes the converter 100A shown in FIG. 2.

[0090] The converter control unit 310A outputs a control signal to the first bridge circuit 110A to control the first arm 31 and the second arm 32. Specifically, the converter control unit 310A controls the on and off of transistors 11 to 14.

[0091] The converter control unit 310A outputs a control signal to the second bridge circuit 120A to control the first arm 41 and the second arm 42. Specifically, the converter control unit 310A controls the on and off of transistors 51 to 54.

[0092] The converter control unit 310A is different from the control device 300 shown in FIG. 4 in that it includes a primary side pulse drive unit 306 and a secondary side pulse drive unit 307 instead of the pulse drive unit 305.

[0093] The feedback control unit 303A executes feedback control based on the signal S12. The feedback control unit 303A calculates the phase difference between the first bridge circuit 110A and the second bridge circuit 120A based on the signal S12. The feedback control unit 303A calculates the phase difference between the first bridge circuit 110A and the second bridge circuit 120A by, for example, PID calculation or the like. The feedback control unit 303A outputs a phase difference command signal S16 indicating the calculated phase difference to the drive pulse generation unit 304A.

[0094] The drive pulse generation unit 304A receives the phase difference command signal S16. The drive pulse generation unit 304A outputs a primary side pulse signal S17 including the pulses input to the transistors 11 to 14 to the primary side pulse drive unit 306 based on the phase difference command signal S16.

[0095] The drive pulse generation unit 304A outputs a secondary side pulse signal S18 including the pulses input to the transistors 51 to 54 to the secondary side pulse drive unit 307 based on the phase difference command signal S16.

[0096] The primary side pulse drive unit 306 converts the voltage level of the primary side pulse signal S17 and generates a primary side drive pulse S19 for switching on and off the transistors 11 to 14. The primary side pulse drive unit 156 outputs the primary side drive pulse S19 to the gates of the transistors 11 to 14.

[0097] The secondary side pulse drive unit 307 converts the voltage level of the secondary side pulse signal S18 and generates a secondary side drive pulse S20 for switching on and off the transistors 51 to 54. The secondary side pulse drive unit 307 outputs the secondary side drive pulse S20 to the gates of the transistors 51 to 54.

[0098] (Inverter control unit) With reference to FIG. 10, a configuration example of the inverter control unit according to the embodiment will be described. FIG. 10 is a diagram showing a configuration example of the inverter control unit according to the embodiment.

[0099] As shown in FIG. 10, the inverter control unit 320 includes a phase detector 501, a three-phase / two-phase converter 502, a rotating coordinate converter 503, a virtual impedance control unit 504, a three-phase / two-phase converter 505, a rotating coordinate converter 506, a subtraction unit 507, an output voltage control unit 508, a PLL unit 509, a circulating current suppression control unit 510, a limiter 511, a subtraction unit 512, a current control unit 513, a three-phase / two-phase converter 514, and a rotating coordinate conversion unit 515.

[0100] The capacitor 401 smoothes the voltage output from the converter 100. The voltage detector 402 detects the output voltage V dc smoothed by the capacitor 401. The voltage detector 402 outputs the detection result of the output voltage V dc to the circulating current suppression control unit 510.

[0101] The current detector 403 detects the output current i inv output from the bridge circuit 70. The current detector 403 outputs the detection result of the current to the three-phase / two-phase converter 514.

[0102] The capacitor 404 smoothes the output voltage from the bridge circuit 70. The voltage detector 405 detects the output voltage V inv The voltage detector 405 outputs the detection result of the output voltage V inv to the three-phase / two-phase converter 505.

[0103] The current detector 82(83) outputs the detection result of the three-phase output current i o flowing through the path from the bridge circuit 70 to the load 2 to the three-phase / two-phase converter 502.

[0104] The switch 407 shields the current output from the bridge circuit 70. The switch 407 is realized by a relay circuit.

[0105] The voltage detector 408 detects the AC voltage V applied from the inverter 200 to the load 2. o The voltage detector 408 outputs the detection result of the voltage to the phase detector 501.

[0106] The phase detector 501 receives the detection result of the AC voltage V from the voltage detector 408. o The phase detector 501 detects the instantaneous phase of the AC voltage V based on the detection result of the AC voltage V. o The phase detector 501 outputs the output voltage phase φ, which is the detection result of the instantaneous phase of the AC voltage V. o The three-phase / two-phase converter 502 receives the detection result of the three-phase output current i from the current detectors 82(83). o The three-phase / two-phase converter 502 performs three-phase / two-phase conversion processing on the three-phase output current i to generate a three-phase / two-phase conversion current. The three-phase / two-phase converter 502 outputs the three-phase / two-phase conversion current to the rotation coordinate converter 503.

[0107] The rotation coordinate converter 503 receives the three-phase / two-phase conversion current from the three-phase / two-phase converter 502. The rotation coordinate converter 503 receives the reference phase φ. o The rotation coordinate converter 503 performs rotation coordinate conversion (so-called dq conversion) on the three-phase / two-phase conversion current based on the reference phase φ to generate a rotation coordinate current. The rotation coordinate current includes the d-axis current Id, which is the active current, and the q-axis current Iq, which is the reactive current. The rotation coordinate converter 503 outputs the q-axis current Iq and the d-axis current Id to the virtual impedance control unit 504. o The virtual impedance control unit 504 receives the q-axis current Iq and the d-axis current Id from the rotation coordinate converter 503. The virtual impedance control unit 504 performs virtual impedance control on the q-axis current Iq and the d-axis current Id to obtain the d-axis output voltage command value Vd

[0108] and the q-axis output voltage command value Vq. ref The virtual impedance control unit 504 receives the q-axis current Iq and the d-axis current Id from the rotation coordinate converter 503. The virtual impedance control unit 504 performs virtual impedance control on the q-axis current Iq and the d-axis current Id to obtain the d-axis output voltage command value Vd ref and the q-axis output voltage command value Vq.

[0109] The virtual impedance control unit 504 receives the q-axis current Iq and the d-axis current Id from the rotation coordinate converter 503. The virtual impedance control unit 504 performs virtual impedance control on the q-axis current Iq and the d-axis current Id to obtain the d-axis output voltage command value Vd ref and the q-axis output voltage command value Vq. refGenerate. The virtual impedance control unit 504 outputs the d-axis output voltage command value Vd ref and the q-axis output voltage command value Vq ref to the subtraction unit 507.

[0110] The three-phase / two-phase converter 505 receives the output voltage V inv from the voltage detector 405. The three-phase / two-phase converter 505 performs a three-phase / two-phase conversion process on the output voltage V inv to generate a three-phase / two-phase conversion voltage. The three-phase / two-phase converter 505 outputs the three-phase / two-phase conversion voltage to the rotating coordinate converter 506.

[0111] The rotating coordinate converter 506 receives the three-phase / two-phase conversion voltage from the three-phase / two-phase converter 505. The rotating coordinate converter 506 receives the reference phase φ ref and performs a rotating coordinate conversion on the three-phase / two-phase conversion voltage based on the reference phase φ ref to generate a rotating coordinate voltage. The rotating coordinate voltage includes the d-axis voltage Vd which is the active voltage and the q-axis voltage Vq which is the reactive voltage. The rotating coordinate converter 506 outputs the d-axis voltage Vd and the q-axis voltage Vq which is the reactive voltage to the subtraction unit 507.

[0112] The subtraction unit 507 receives the d-axis output voltage command value Vd ref and the q-axis output voltage command value Vq ref from the virtual impedance control unit 504. The subtraction unit 507 receives the d-axis voltage Vd and the q-axis voltage Vq from the rotating coordinate converter 506. The subtraction unit 507 calculates the difference between the d-axis output voltage command value Vd ref and the d-axis voltage Vd. The subtraction unit 507 calculates the difference between the q-axis output voltage command value Vq ref and the q-axis voltage Vq. The subtraction unit 507 outputs the difference between the d-axis output voltage command value Vdref and the d-axis voltage Vd and the difference between the q-axis output voltage command value Vqref and the q-axis voltage Vq to the output voltage control unit 508.

[0113] The output voltage control unit 508 receives the difference between the d-axis output voltage command value Vd ref and the d-axis voltage Vd and the q-axis output voltage command value Vq refreceives the difference between the d-axis output voltage command value Vd and the q-axis voltage Vq. The output voltage control unit 508 performs proportional-integral control so that the difference between the d-axis output voltage command value Vd and the d-axis voltage Vd becomes small, and generates the d-axis current Id. The output voltage control unit 508 performs proportional-integral control so that the difference between the q-axis output voltage command value Vq and the q-axis voltage Vq becomes small, and generates the q-axis current Iq. The output voltage control unit 508 outputs the d-axis current Id and the q-axis current Iq to the limiter 511. ref The PLL (Phase Locked Loop) unit 509 performs frequency stabilization control. The PLL unit 509 is realized by a PLL circuit. The PLL unit 509 receives the output voltage phase φ from the phase detector 501. The PLL unit 509 generates a reference phase φ that synchronizes with the output voltage phase φ based on the output voltage phase φ and the rated frequency fa of the inverter 200. ref The PLL unit 509 outputs the reference phase φ to the rotation coordinate converter 503 and the rotation coordinate converter 506.

[0114] The circulating current suppression control unit 510 receives the output voltage V from the voltage detector 402. The circulating current suppression control unit 510 calculates the lower limit value of the current command value and outputs the calculation result to the limiter 511. ref The reference phase φ ref is output to the rotation coordinate converter 503 and the rotation coordinate converter 506.

[0115] The configuration example of the circulating current suppression unit according to the embodiment will be described with reference to FIG. 11. FIG. 11 is a diagram showing the configuration example of the circulating current suppression control unit according to the embodiment. dc As shown in FIG. 11, the circulating current suppression control unit 510 includes a subtraction unit 601 and a current command value calculation unit 602.

[0116] The subtraction unit 601 receives the output voltage V from the voltage detector 402. The subtraction unit 601 receives V

[0117] Ref + ΔV. V

[0118] Ref is the specified value of the output voltage. ΔV dc is received by the subtraction unit 601. The subtraction unit 601 receives V dc Ref + ΔV dc is received by the subtraction unit 601. V dc Ref is the specified value of the output voltage. ΔV dc is the difference between the output voltage V dcis the allowable variation value. That is, V dc Ref + ΔV dc represents the upper limit value of the allowable output voltage. The subtraction unit 601 subtracts the output voltage V dc Ref + ΔV dc from the output voltage V dc and outputs the calculation result to the current command value calculation unit 602.

[0119] The current command value calculation unit 602 calculates the lower limit value of the current command value based on the calculation result of the difference between the output voltage upper limit value V dc Ref + ΔV dc and the output voltage V dc . The lower limit value of the current command value is calculated so as not to increase the output voltage V dc above the allowable value. Specifically, when the output voltage V dc is equal to or higher than the output voltage upper limit value V dc Ref + ΔV dc , the current command value calculation unit 602 calculates the lower limit value of the current command value of the output current of the inverter 200 to a value that changes in the positive direction (discharge direction). The current command value calculation unit 602 outputs the lower limit value of the current command value to the limiter 511.

[0120] The limiter 511 receives the d-axis current Id and the q-axis current Iq from the output voltage control unit 508. The limiter 511 receives the lower limit value of the current command value from the circulating current suppression control unit 510. The limiter 511 generates a d-axis current command signal with the lower limit value of the d-axis current Id limited based on the lower limit value of the current command value. The limiter 511 outputs the d-axis current command signal and the q-axis current command signal to the subtraction unit 512.

[0121] The three-phase / two-phase converter 514 receives the detection result of the output current i inv from the current detector 403. The three-phase / two-phase converter 514 performs a three-phase / two-phase conversion process on the output current i inv to generate a three-phase / two-phase conversion current. The three-phase / two-phase converter 514 outputs the three-phase / two-phase conversion current to the rotation coordinate converter 515.

[0122] The rotational coordinate converter 515 receives a three-phase / two-phase conversion current from the three-phase / two-phase converter 514. The rotational coordinate converter 515 receives a reference phase φ ref thereof. Based on the reference phase φ ref , the rotational coordinate converter 515 performs a rotational coordinate conversion on the three-phase / two-phase conversion current to generate a rotational coordinate current. The rotational coordinate current includes a d-axis current Id and a q-axis current Iq. The rotational coordinate converter 515 outputs the q-axis current Iq and the d-axis current Id to the subtraction unit 512.

[0123] The subtraction unit 512 receives a d-axis current command signal and a q-axis current command signal from the limiter 511. The subtraction unit 512 receives the d-axis current Id and the q-axis current Iq from the rotational coordinate converter 515. The subtraction unit 512 calculates the difference between the d-axis current command signal and the d-axis current Id of the output current i inv . The subtraction unit 512 calculates the difference between the q-axis current command signal and the q-axis current Iq of the output current i inv . The subtraction unit 512 outputs the difference between the d-axis current command signal and the d-axis current Id and the difference between the q-axis current command signal and the q-axis current Iq to the current control unit 513.

[0124] The current control unit 513 receives the difference between the d-axis current command signal and the d-axis current Id and the difference between the q-axis current command signal and the q-axis current Iq from the subtraction unit 512. The current control unit 513 generates a switching signal such that the difference between the d-axis current command signal and the d-axis current Id and the difference between the q-axis current command signal and the q-axis current Iq received from the subtraction unit 512 become smaller. The current control unit 513 outputs the generated switching signal to the transistors 91 to 96.

[0125] By performing such control, the inverter control unit 320 causes the output voltage V dc to be the output voltage upper limit value V dc Ref + ΔV dcWhen it rises above, the current output command value of the inverter 200 is changed in the positive direction. As a result, the inverter control unit 320 can suppress the circulating current generated between the converter 100 and the inverter 200. Since the present disclosure can suppress the generation of the circulating current with a simple configuration by software control, the cost can also be reduced.

[0126] 〔Modification Example of Power Supply Device〕 (First Modification Example) Using FIG. 12, a configuration example of a power supply device according to a first modification example of the embodiment will be described. FIG. 12 is a diagram showing a configuration example of a power supply device according to a first modification example of the embodiment.

[0127] As shown in FIG. 12, in the first modification example of the embodiment, the input terminals of the converter 100-1 to the converter 100-2 are electrically connected to the output terminals of the DC power supply 1-1 to the DC power supply 1-n, respectively. That is, in the first modification example of the embodiment, the converter 100-1 to the converter 100-n are different from the embodiment shown in FIG. 1 in that currents are input from different DC power supplies.

[0128] For example, in the first modification example of the embodiment, the converter 100-1 to the converter 100-n are respectively supplied with DC currents i bat1 from the DC power supply 1-1 to the DC power supply 1-n outputting DC current i batn . The DC current i bat1 to the DC current i batn may have the same magnitude or different magnitudes.

[0129] (Second Modification Example) Using FIG. 13, a configuration example of a power supply device according to a second modification example of the embodiment will be described. FIG. 13 is a diagram showing a configuration example of a power supply device according to a second modification example of the embodiment.

[0130] As shown in FIG. 13, in the second modification of the embodiment, the output terminals of the inverters 200-1 to 200n are electrically connected to the output terminals of the AC power supply 5, which is different from the first modification shown in FIG. 12. That is, in the second modification of the embodiment, two elements, namely the load 2 and the AC power supply 5, are provided on the secondary side. Note that the AC power supply 5 may be provided on the secondary side in FIG. 1.

[0131] The AC power supply 5 is an AC power supply provided on the secondary side. The AC power supply 5 follows the AC output voltage of the inverters 200-1 to 200-n and outputs an AC current. The control device 300 controls the AC voltage V ac to charge the DC power supplies 1-1 to 1-n from the AC power generated by the AC power supply 5.

[0132] In the second modification, the output power from the AC power supply 5 is applied to the output line of the inverter 200 and operates in a direction to increase the AC voltage. The circulating current suppression control unit 510 detects the increase in the AC voltage and executes a process for suppressing the circulating current while maintaining the AC voltage.

[0133] With reference to FIG. 14, a configuration example of the circulating current suppression control unit according to the modification of the embodiment will be described. FIG. 14 is a diagram showing a configuration example of the circulating current suppression control unit according to the modification of the embodiment.

[0134] As shown in FIG. 14, the circulating current suppression control unit 510A includes a subtraction unit 601, a current command value calculation unit 602, a subtraction unit 603, a current command value calculation unit 604, and an addition unit 605. The circulating current suppression control unit 510A is different from the circulating current suppression control unit 510 shown in FIG. 11 in that it includes the subtraction unit 603, the current command value calculation unit 604, and the addition unit 605. In the example shown in FIG. 14, the current command value calculation unit 602 outputs the lower limit value of the current command value to the addition unit 605.

[0135] The subtraction unit 603 receives the V of the AC voltage rotation coordinate conversion result d The AC voltage V d is the AC voltage V obtained by rotation coordinate conversion acIt is for quickly detecting changes in. The subtraction unit 603 subtracts V ac Ref + ΔV ac from the received value. V ac Ref is the specified value of the AC voltage output by the inverter 200. ΔV ac is the allowable variation value for the AC voltage V ac . That is, V ac Ref + ΔV ac represents the upper limit value of the allowable AC voltage. The subtraction unit 603 calculates the difference between the AC voltage upper limit value V ac Ref + ΔV ac and the AC voltage V d and outputs the calculation result to the current command value calculation unit 604.

[0136] The current command value calculation unit 604 calculates the lower limit value of the current command value based on the calculation result of the difference between the AC voltage upper limit value V ac Ref + ΔV ac and the AC voltage V d . The lower limit value of the current command value is calculated so as not to increase the AC voltage V ac above the allowable value. Specifically, when the AC voltage V d is equal to or higher than the AC voltage upper limit value V ac Ref + ΔV ac , the current command value calculation unit 604 calculates the lower limit value of the current command value of the output current of the inverter 200 to a value that changes in the negative direction (charging direction). The current command value calculation unit 604 outputs the lower limit value of the current command value to the addition unit 605.

[0137] The addition unit 605 adds together the current command value calculated by the current command value calculation unit 602 and the current command value calculated by the current command value calculation unit 604. The addition unit 605 outputs the current command value obtained by adding together the current command value calculated by the current command value calculation unit 602 and the current command value calculated by the current command value calculation unit 604 to the limiter 511.

[0138] By performing such control, the inverter control unit 320 ensures that when the AC voltage V ac is equal to or higher than the AC voltage upper limit value V ac Ref + ΔV acWhen it rises above, the current output command value of the inverter 200 is changed in the negative direction, whereby the inverter control unit 320 can suppress the circulating current generated between the converter 100 and the inverter 200. Since the present disclosure can suppress the generation of the circulating current with a simple configuration by software control, the cost can also be reduced.

[0139] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited by the contents of these embodiments. Further, the above-described components include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those within a so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or changes of the components can be made without departing from the gist of the above-described embodiments.

Explanation of Reference Numerals

[0140] 1 DC power supply 2 Load 3, 4, 77, 78, 79, 401, 404 Capacitor 5 AC power supply 11, 12, 13, 14, 51, 52, 53, 54, 91, 92, 93, 94, 95, 96 Transistor 20, 21, 74, 75, 76 Reactor 22 Transformer 22a First winding 22b Second winding 22c Core 31, 41, 71 First arm 32, 42, 72 Second arm 73 Third arm 70 Bridge circuit 80, 81, 402, 405, 408 Voltage detector 82, 83 Current detector 100, 100A Converter 110 Bridge circuit 110A First bridge circuit 120A Second bridge circuit 200 Inverter 300 Control device 301 Parallel operation control unit 302, 313, 507, 512, 601, 603 Subtraction unit 303, 303A Feedback control unit 304, 304A Drive pulse generation unit 305 Pulse drive unit 306 Primary side pulse drive unit 307 Secondary side pulse drive unit 310 Converter control unit 311 Low-pass filter 312 Virtual bidirectional diode control unit 320 Inverter control unit 400 Virtual bidirectional diode circuit 407 Switch 501 Phase detector 502, 505, 514 Three-phase / two-phase converter 503, 506, 515 Rotating coordinate converter 504 Virtual impedance control unit 508 Output voltage control unit 509 PLL unit 510 Circulating current suppression control unit 511 Limiter 513 Current control unit 602, 604 Current command value calculation unit 605 Addition unit 1000, 1100 Power supply device

Claims

1. A bidirectional converter with its input terminal electrically connected to the output terminal of a DC power supply, A bidirectional inverter with its input terminal electrically connected to the output terminal of the bidirectional converter, A control device for controlling the operations of the bidirectional converter and the bidirectional inverter, and The control device performs control to add a virtual bidirectional diode circuit including a virtual bidirectional diode to the output terminal of the bidirectional converter. A power supply device.

2. The control device detects the DC voltage input from the bidirectional converter to the bidirectional inverter, and when the DC voltage rises above a predetermined value, changes the current output command value of the bidirectional inverter in the positive direction. The power supply device according to Claim 1.

3. Including a plurality of the bidirectional converters and a plurality of the bidirectional inverters, The input terminals of the plurality of bidirectional converters are each connected in parallel to the output terminal of the DC power supply, The output terminals of the plurality of bidirectional converters are each connected to the input terminals of the corresponding plurality of bidirectional inverters, The output terminals of the plurality of bidirectional inverters are each connected in parallel. The power supply device according to Claim 1 or 2.

4. Including a plurality of the DC power supplies, a plurality of the bidirectional converters, and a plurality of the bidirectional inverters The output terminals of the plurality of DC power supplies are each connected to the input terminals of the corresponding plurality of bidirectional converters, The output terminals of the plurality of bidirectional converters are each connected to the input terminals of the corresponding plurality of bidirectional inverters, The output terminals of the plurality of bidirectional inverters are each connected in parallel. The power supply device according to Claim 1 or 2.

5. Including an AC power supply to which the output terminals of each of the plurality of bidirectional inverters are connected at the output terminal, The output terminals of the bidirectional inverters and the output terminals of the AC power supply are connected in parallel, The control device controls the AC voltage of the AC power supply to charge the DC power supply. The power supply device according to Claim 3.

6. When the AC voltage rises above a predetermined value, the control device changes the current command value of the bidirectional inverter in the negative direction. The power supply device according to Claim 5.

7. The control device detects a direct current output from the bidirectional converter and controls the virtual bidirectional diode based on the direct current output from the bidirectional converter. The power supply device according to claim 1.

8. The control device adds a virtual bidirectional diode circuit including a virtual bidirectional diode to the output terminal of the bidirectional converter, and performs control to increase or decrease the output voltage of the bidirectional converter when the direction of the current flowing through the bidirectional converter changes. The power supply device according to claim 1.

9. A control method for a power supply device, including a bidirectional converter whose input terminal is electrically connected to the output terminal of a direct current power supply, a bidirectional inverter whose input terminal is electrically connected to the output terminal of the bidirectional converter, and a control device that controls the operations of the bidirectional converter and the bidirectional inverter, wherein the control device performs control to add a virtual bidirectional diode circuit including a virtual bidirectional diode to the output terminal of the bidirectional converter. A control method for a power supply device.

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