A bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies and a control method thereof

Abstract

The present invention discloses a bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies and a control method thereof, comprising four wiring terminals, wherein the first wiring terminal, the second wiring terminal and the third wiring terminal are respectively connected to the corresponding first bridge arm midpoint of the power converter, the second bridge arm midpoint of the power converter and the third bridge arm midpoint of the power converter through the corresponding first inductor L1, the second inductor L2 and the third inductor L3, the fourth wiring terminal is connected to the fourth bridge arm midpoint of the power converter, the four power converter bridge arms are connected in parallel and in parallel with the bus capacitor C4; and further comprising a first main switch device connected between the first wiring terminal and the first inductor L1, a second main switch device connected between the second wiring terminal and the second inductor L2, and a third main switch device connected between the third wiring terminal and the third inductor L3. The present invention can achieve the effect of being compatible with single-phase and three-phase AC power supplies, can effectively expand the scope of use of the circuit, is convenient for users to use, and reduces costs.

Description

Technical Field

[0001] The invention belongs to the technical field of electric vehicle charging / energy storage, and relates to a bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies and a control method thereof. Background Art

[0002] The existing three-phase and single-phase bidirectional ACDC circuits are not compatible. In some practical applications, there are only single-phase circuits (such as Figure 1 as shown) or three-phase AC power supply (as Figure 2 As shown in the figure, people need to develop two sets of devices to meet the requirements of different power supplies, which is costly, inconvenient to use and has poor compatibility. Summary of the invention

[0003] In order to solve the above problems, the purpose of the present invention is to provide a bidirectional ACDC circuit and a control method thereof that are compatible with three-phase and single-phase AC power supplies. Through reasonable circuit structure design, the single-phase and three-phase compatibility effects are achieved, which is convenient for users to use and reduces costs.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is a bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies, comprising four wiring terminals, wherein the first wiring terminal, the second wiring terminal and the third wiring terminal are respectively connected to the corresponding midpoint of the first bridge arm of the power converter, the midpoint of the second bridge arm of the power converter and the midpoint of the third bridge arm of the power converter through the corresponding first inductor L1, the second inductor L2 and the third inductor L3, the fourth wiring terminal is connected to the midpoint of the fourth bridge arm of the power converter, and the four power converter bridge arms are connected in parallel and in parallel with the bus capacitor C4;

[0005] Also includes a first main switch device connected between the first wiring terminal and the first inductor L1, a second main switch device connected between the second wiring terminal and the second inductor L2, and a third main switch device connected between the third wiring terminal and the third inductor L3;

[0006] The fourth terminal is connected to between the first main switch device and the first inductor L1, between the second main switch device and the second inductor L2, and between the third main switch device and the third inductor L3 through the first capacitor C1, the second capacitor C2 and the third capacitor C3 respectively;

[0007] It also includes a fifth short-circuiting switch device for connecting the first wiring terminal and the second wiring terminal and a sixth short-circuiting switch device for connecting the third wiring terminal and the fourth wiring terminal.

[0008] One end of the fifth short-circuit switch device is connected to the first terminal through the first main switch device, and the other end is connected to the second terminal through the second main switch device; or the fifth short-circuit switch device is directly connected between the first terminal and the second terminal.

[0009] One end of the sixth short-circuit switch device is connected to the third wiring terminal through the third main switch device, and the other end is directly connected to the fourth wiring terminal; or the sixth short-circuit switch device is directly connected between the third wiring terminal and the fourth wiring terminal;

[0010] Alternatively, one end of the sixth short-circuit switch device is connected to the third wiring terminal via the third inductor L3 and the third main switch device, and the other end is connected to the fourth wiring terminal via the fourth inductor L4.

[0011] The fourth connecting terminal is connected to the midpoint of the fourth bridge arm of the power converter via the fourth inductor L4.

[0012] The first main switch device is connected in parallel with a first soft-start circuit, the second main switch device is connected in parallel with a second soft-start circuit, and the third main switch device is connected in parallel with a third soft-start circuit.

[0013] The first main switch device is connected in parallel with a first soft-start circuit, the second main switch device is connected in parallel with a second soft-start circuit, and the third main switch device is connected in parallel with a third soft-start circuit.

[0014] The first connecting terminal, the second connecting terminal, the third connecting terminal and the fourth connecting terminal are respectively an A-phase connecting terminal, a B-phase connecting terminal, a C-phase connecting terminal and an N-phase connecting terminal.

[0015] The present invention also provides a control method for a bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies. When working in the forward direction, the soft-start circuit is first turned on, and the wiring terminal connected to the soft-start circuit is connected to the bus capacitor C4, and the bus capacitor C4 is soft-started. After the soft start, the switch device between the wiring terminal connected to the AC power supply and the bus capacitor C4 is turned on, and then the soft-start circuit is turned off to complete the AC to DC conversion through the power converter;

[0016] During reverse inversion, when the AC power source type is three-phase AC, first disconnect all switch devices, and after the power converter completes the software inversion soft start, when the inverter output amplitude and phase meet the output conditions, connect the main switch device between the terminal connected to the AC power source and the bus capacitor C4 to achieve DC to AC conversion; or

[0017] During reverse inversion, when the AC power supply type is single-phase AC, first, the short-circuit relay and all the main switching devices in the loop from the fourth terminal to the midpoint of the third bridge arm and the midpoint of the fourth bridge arm are energized, and the remaining switching devices are disconnected. After the power converter completes the software inverter soft start, when the inverter output amplitude and phase meet the output conditions, all the main switching devices in the loop from the first terminal to the midpoint of the first bridge arm and the midpoint of the second bridge arm are energized to achieve DC to AC conversion.

[0018] When the AC power supply is three-phase AC power, the connection method between the terminal block and the AC power supply is a three-phase four-wire system or a three-phase three-wire system.

[0019] The switch device comprises a main switch device and a short switch device.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects: the method automatically adapts to three-phase or single-phase AC power supply according to the different AC voltages, and can provide a three-phase and single-phase compatible bidirectional ACDC circuit with good compatibility. In the circuit, by adding reasonable switching devices and using different control timings, the single-phase and three-phase compatibility effects can be achieved. In addition, the scope of use of the circuit can be effectively expanded, which is convenient for users to use and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an existing single-phase power supply circuit.

[0022] Figure 2 It is a three-phase power supply circuit in the prior art.

[0023] Figure 3 It is a schematic diagram of the circuit structure of a certain embodiment of the present invention.

[0024] Figure 4 for Figure 3 Schematic diagram of the equivalent circuit structure when working on a single-phase power supply.

[0025] Figure 5 It is another embodiment of the present invention.

[0026] Figure 6 It is another embodiment of the present invention.

[0027] Figure 7 It is another embodiment of the present invention.

[0028] Figure 8 It is another embodiment of the present invention.

[0029] Fig. 9 It is another embodiment of the present invention.

[0030] Fig.10 It is another embodiment of the present invention.

[0031] Fig.11 It is another embodiment of the present invention.

[0032] Fig.12 It is another embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0034] In all embodiments of the present invention, the first terminal, the second terminal, the third terminal and the fourth terminal are designated as A-phase terminal, B-phase terminal, C-phase terminal and N-phase terminal; the switching device selection relay used in the embodiment is for the convenience of clear description of the technical solution and should not be understood as a limitation of this solution.

[0035] The circuit structure of the present invention includes four wiring terminals, wherein the first wiring terminal A, the second wiring terminal B and the third wiring terminal C are respectively connected to the corresponding midpoint of the first bridge arm of the power converter, the midpoint of the second bridge arm of the power converter and the midpoint of the third bridge arm of the power converter through the corresponding first inductor L1, the second inductor L2 and the third inductor L3, the fourth wiring terminal N is connected to the midpoint of the fourth bridge arm of the power converter, and the four power converter bridge arms are connected in parallel and in parallel with the bus capacitor C4; and also includes a main relay Relay1 (i.e., a first main switch device) connected between the first wiring terminal A and the first inductor L1, a main relay Relay2 (i.e., a second main switch device) connected between the second wiring terminal B and the second inductor L2 The invention also includes a main relay Relay1 (i.e., a main switch device) and a main relay Relay3 (i.e., a third main switch device) connected between the third terminal C and the third inductor L3; the fourth terminal N is connected between the main relay Relay1 and the first inductor L1, between the main relay Relay2 and the second inductor L2, and between the main relay Relay3 and the third inductor L3 through the first capacitor C1, the second capacitor C2, and the third capacitor C3 respectively; and also includes a short-circuiting relay Relay5 (i.e., a fifth short-circuiting switch device) for connecting the first terminal A and the second terminal B and a short-circuiting relay Relay6 (i.e., a sixth short-circuiting switch device) for connecting the third terminal C and the fourth terminal N.

[0036] like Figure 3As shown, in this embodiment, a first soft-start circuit is connected in parallel to the main relay Relay1, and the first soft-start circuit is composed of a soft-start resistor R1 and a soft-start normally closed relay Relay11 in series; one end of the short-circuit relay Relay5 is connected to the first wiring terminal A through the main relay Relay1, and the other end is connected to the second wiring terminal B through the main relay Relay2; one end of the short-circuit relay Relay6 is connected to the third wiring terminal C through the main relay Relay3, and the other end is directly connected to the fourth wiring terminal N;

[0037] The control strategy of this embodiment is as follows: the type and connection mode of the AC power supply are determined by detecting the voltage amplitude and phase of the three wiring terminals A, B and C to N:

[0038] When the AC power supply is a three-phase four-wire system, A, B, and C are connected to the three-phase live wires respectively, and N is connected to the neutral wire:

[0039] When working in the forward direction (i.e. AC-DC), phase A forms a loop through the soft-start resistor R1, the soft-start normally closed relay Relay11 and the N line to soft-start the bus capacitor C4. This circuit structure design has better compatibility with the auxiliary source. Under this control strategy, the auxiliary source can perform the following strategy even if it is connected to the bus.

[0040] When the bus capacitor C4 soft-starts to the peak value of the input phase voltage, the main relay Relay2 or Relay3 of one of the B or C paths is energized, and the A phase forms a loop with the B phase or the C phase through the soft-start resistor R1 and the soft-start normally closed relay Relay11 to soft-start the bus capacitor C4. When the bus capacitor soft-starts to the peak value of the input line voltage, all the main relays Relay1, Relay2 and Relay3 are energized, and the soft-start normally closed relay Relay11 is disconnected. Then, the AC to DC conversion is completed through the three-phase four-bridge-arm PWM converter.

[0041] When reversely inverting DC to AC, first disconnect all relays. After the three-phase four-bridge arm PWM converter completes the software inverter soft start, when the inverter output amplitude and phase meet the output conditions, energize the A, B, C main relays Relay1, Relay2, Relay3 to realize DC to AC conversion.

[0042] When the AC power supply is a three-phase three-wire system, A, B, and C are connected to the three-phase live wires respectively, and N is left unconnected:

[0043] When working in the forward direction, the main relay Relay2 or Relay3 of one of the B or C paths is energized, and the A phase forms a loop with the B or C phase through the soft-start resistor R1 and the soft-start normally closed relay Relay11 to soft-start the bus capacitor C4. When the bus capacitor soft-starts to the peak value of the input line voltage, all the main relays Relay1, Relay2 and Relay3 are energized, and the soft-start normally closed relay Relay11 is disconnected. Then, the AC to DC conversion is completed through the three-phase four-bridge-arm PWM converter.

[0044] When reversely inverting DC to AC conversion, first disconnect all relays. After the three-phase four-bridge arm PWM converter completes the software inverter soft start, when the inverter output amplitude and phase meet the output conditions, attract all main relays Relay1, Relay2 and Relay3 to realize DC to AC conversion.

[0045] Figure 3 In the case of single-phase AC power supply, A is connected to the single-phase AC live wire L, and N is connected to the single-phase AC neutral wire:

[0046] When working in the forward direction (AC-DC), the live wire forms a loop through the soft-start resistor R1, the soft-start normally closed relay Relay11 and the N line to soft-start the bus capacitor C4. After the bus capacitor soft-start is completed, the A-way main relay Relay1 and the short-circuit relays Relay5 and Relay6 are attracted, the soft-start normally closed relay Relay11 is disconnected, and the B-way and C-way relays Relay2 and Relay3 are kept in the tripped (disconnected) state. At this time, the input mode is equivalent to Figure 4 As shown; L and N realize the AC to DC conversion of full-bridge interleaved PFC through a three-phase four-bridge-arm PWM converter.

[0047] During reverse inversion (DC-AC), short-circuit relays Relay5 and Relay6 are energized, and all relays except Relay5 and Relay6 are disconnected. After the software completes the inverter soft start, main relay Relay1 of channel A is energized to achieve DC to AC conversion.

[0048] Figure 5 is another embodiment of the present invention, the circuit structure is Figure 3 The difference is that the position of the short-circuit relay Relay6 is different. One end of the short-circuit relay Relay6 is connected to the third terminal C through the third inductor L3 and the main relay Relay3, and the other end is connected to the fourth terminal N through the fourth inductor L4. The effect is that the inductance is different when the single-phase works, and the control mode is different. Figure 3 Completely consistent; such as Figure 5 In the embodiment shown, when the AC power supply is single-phase AC, the short-circuit relay Relay6 is turned on, and the current does not pass through the third inductor L3, but all flows through the fourth inductor L4. Figure 3 In single-phase, the inductor current flows through L4 and L3. Figure 3 The current flowing through a single inductor L4 or L3 is Figure 5 Flowing through half of L4, for the same volume of inductor, Figure 5 The current through L4 is Figure 3 is twice that of L4, so Figure 5 The inductance of L4 in the circuit is too small, the input ripple current is large, and the THDI index of the corresponding harmonic pollution is poor.

[0049] Figure 6 is another embodiment of the present invention, and Figure 3 The difference between the circuit structures shown is that the position of relay Relay6 is different. Figure 6 In the embodiment shown, one end of the short-circuit relay Relay6 is directly connected to the third terminal C, and the other end is directly connected to the fourth terminal N; when the alternating current is three-phase, the control mode is the same as Figure 3 Same; when the AC power is single-phase, the control mode is the same as Figure 3 There are some differences, as follows:

[0050] exist Figure 6 In the circuit structure shown, when the AC power supply is single-phase, A is connected to the single-phase AC live wire L, and N is connected to the single-phase AC neutral wire. When working in the forward direction (AC-DC), the live wire forms a loop through the soft-start resistor R1, the soft-start normally closed relay Relay11 and the N line to soft-start the bus capacitor C4. After the bus capacitor soft-start is completed, the A-way main relay Relay1, the C-way main relay Relay3 and the short-circuit relays Relay5 and Relay6 are attracted, the soft-start relay normally closed appliance Relay11 is disconnected, and the B-way main relay Relay2 is kept in the tripped state. At this time, the input mode is equivalent to Figure 4 As shown in Figure 1, L and N realize the AC to DC conversion of full-bridge interleaved PFC through a three-phase four-bridge PWM converter.

[0051] During reverse inversion (DC-AC), the main relay Relay3 of line C is energized, relays Relay5 and Relay6 are short-circuited, and the soft-start normally closed relay Relay11, main relays Realy1 and Relay2 are disconnected. After the software completes the reverse soft start, the main relay Relay1 of line A is energized to realize DC to AC conversion.

[0052] Figure 7 is another embodiment of the present invention, and Figure 3 The difference is that the short-circuit relays Relay5 and Relay6 are located in different positions. Figure 7In the embodiment shown, one end of the short-circuit relay Relay5 is directly connected to the first terminal A, and the other end is directly connected to the second terminal B; one end of the short-circuit relay Relay6 is directly connected to the third terminal C, and the other end is directly connected to the fourth terminal N; when the alternating current is three-phase, the control mode is the same as Figure 3 Same; when the AC power is single-phase, the control mode is the same as Figure 3 Different, as follows:

[0053] exist Figure 7 In the illustrated embodiment, when the AC power supply is single-phase, A is connected to the single-phase AC live wire L, and N is connected to the single-phase AC neutral wire. When working in the forward direction (AC-DC), the live wire forms a loop through the soft-start resistor R1, the soft-start normally closed relay Relay11 and the N line to soft-start the bus capacitor C4. After the bus capacitor soft-start is completed, the A-way main relay Relay1, the B-way relay Relay2, the C-way main relay Relay3 and the short-circuit relays Relay5 and Relay6 are attracted, and the soft-start normally closed relay Relay11 is disconnected. At this time, the input mode is equivalent to Figure 4 As shown in Figure 1, L and N realize the AC to DC conversion of full-bridge interleaved PFC through a three-phase four-bridge PWM converter.

[0054] During reverse inversion (DC-AC), the C-way main relay Relay3, short-circuit relays Relay5 and Relay6 are energized, and the remaining relays are disconnected. After the software completes the inverter soft start, the main relays Relay1 and Relay2 are energized to achieve DC to AC conversion; of course, in the control process of this embodiment, during reverse inversion (DC-AC), the C-way main relay Relay3 and short-circuit relay Relay6 may be energized first, and all relays except Relay3 and Relay6 may be disconnected. After the software completes the inverter soft start, the main relays Relay1, Relay2 and short-circuit relay Relay5 are energized to achieve DC to AC conversion.

[0055] Figure 8 is another embodiment of the present invention, and Figure 3 The difference is that the position of the short-circuit relay Relay5 is different. Figure 8 In the embodiment shown, one end of the short-circuit relay Relay5 is directly connected to the first terminal A, and the other end is directly connected to the second terminal B; when the alternating current is three-phase, the control mode is the same as Figure 3 Same; when the AC power is single-phase, the control mode is the same as Figure 3 Different, as follows:

[0056] Figure 8In the example, when the AC power supply is single-phase, A is connected to the single-phase AC live wire L, and N is connected to the single-phase AC neutral wire. When working in the forward direction (AC-DC), the live wire forms a loop through the soft-start resistor R1, the soft-start normally closed relay Relay11 and the N line to soft-start the bus capacitor C4. After the bus capacitor soft-start is completed, the A-way main relay Relay1, the B-way main relay Relay2 and the short-circuit relays Relay5 and Relay6 are attracted, and the soft-start normally closed relay Relay11 is disconnected. At this time, the input mode is equivalent to Figure 4 As shown in Figure 1, L and N realize the AC to DC conversion of full-bridge interleaved PFC through a three-phase four-bridge PWM converter.

[0057] During reverse inversion (DC-AC), the short-circuit relays Relay5 and Relay6 are energized, and the remaining relays are disconnected. After the software completes the soft start of the inverter, the main relays Relay1 and Relay2 are energized to achieve DC to AC conversion. Of course, in the control process of this embodiment, during reverse inversion (DC-AC), the short-circuit relay Relay6 may be energized first, and all relays except Relay6 may be disconnected. After the software completes the soft start of the inverter, the main relays Relay1 and Relay2 and the short-circuit relay Relay5 are energized to achieve DC to AC conversion.

[0058] Fig. 9 is another embodiment of the present invention, and Figure 8 The difference is the position of relay Relay6. Fig. 9 In the embodiment shown, one end of the short-circuit relay Relay6 is connected to the third terminal C through the third inductor L3 and the main relay Relay3, and the other end is connected to the fourth terminal N through the fourth inductor L4; Figure 8 The circuit structure shown has the same control method.

[0059] Fig.10 is another embodiment of the present invention, and Figure 3 The difference is that the circuit structure is simplified, the fourth inductor L4 of the N-way connection is cancelled, and the N-way has no inductor. The effect is that the inductance is different when working in single-phase mode, the adaptability to unbalanced load is poor when three-phase inverter is inverted, and the control mode and Figure 3 Consistent.

[0060] Fig.11 is another embodiment of the present invention, and Figure 3 The difference is that the main relay of phase B is connected in parallel with a second soft-start circuit, which further optimizes the control strategy of the circuit of the present invention. When the forward rectifier input is three-phase, there is no need to control the timing of each main relay. After the soft-start is completed, the three main relays Relay1, Relay2 and Relay3 can be simultaneously attracted. In this embodiment, when the AC power is single-phase, the control mode and Figure 3Similarly, the three-phase ACDC soft-start circuit and control method of this embodiment are as follows:

[0061] Fig.11 In the case of a three-phase four-wire AC power supply, A, B and C are connected to the three-phase live wires respectively, and N is connected to the neutral wire. When working in the forward direction (AC-DC), phase A forms a loop through the soft-start resistor R1 and the soft-start normally closed relay Relay11, and phase B forms a loop through the soft-start resistor R2 and the soft-start normally closed relay Relay21 to provide soft-start to the bus capacitor C4;

[0062] When the bus capacitor soft-starts to the peak value of the input phase voltage, all main relays Relay1, Relay2 and Relay3 are energized, and the soft-start normally closed relays Relay11 and Relay21 are disconnected. Then, the AC to DC conversion is completed through the three-phase four-bridge-arm PWM converter.

[0063] When reversely inverting DC to AC conversion, first disconnect all relays. After the three-phase four-bridge arm PWM converter completes the software inverter soft start, when the inverter output amplitude and phase meet the output conditions, attract all main relays Relay1, Relay2 and Relay3 to realize DC to AC conversion.

[0064] When the AC power supply is a three-phase three-wire system, A, B and C are connected to the three-phase live wires respectively, and N is left floating. When working in the forward direction, the A phase forms a loop through the soft-start resistor R1 and the soft-start normally closed relay Relay11, and the B phase soft-start resistor R2 and the soft-start normally closed relay Relay21 to soft-start the bus capacitor C4. When the bus capacitor soft-starts to the peak value of the input line voltage, all the main relays Relay1, Relay2 and Relay3 are attracted, and the soft-start normally closed relays Relay11 and Relay21 are disconnected. Then, the AC to DC conversion is completed through the three-phase four-bridge arm PWM converter.

[0065] When reversely inverting DC to AC conversion, first disconnect all relays. After the three-phase four-bridge arm PWM converter completes the software inverter soft start, when the inverter output amplitude and phase meet the output conditions, attract all main relays Relay1, Relay2 and Relay3 to realize DC to AC conversion.

[0066] Fig.12 is another embodiment of the present invention, and Figure 3 The difference is that the second soft-start circuit and the third soft-start circuit are connected in parallel to the main relays of phase B and phase C respectively. The control of the circuit in this embodiment is simple. When the three-phase forward rectifier input is in progress, there is no need to control the timing of each main relay. After the soft start is completed, the three main relays Relay1, Relay2 and Relay3 can be simultaneously attracted. In this embodiment, when the AC power is single-phase, the control method and Figure 3Similarly, the three-phase ACDC soft-start circuit and control method of this embodiment are as follows:

[0067] When the AC power supply is a three-phase four-wire system, A, B and C are connected to the three-phase live wires respectively, and N is connected to the neutral wire. When working in the forward direction (AC-DC), the A phase forms a loop to soft-start the bus capacitor C4 through the soft-start resistor R1 and the soft-start normally closed relay Relay11, the B phase soft-start resistor R2 and the soft-start normally closed relay Relay21, and the C phase soft-start resistor R3 and the soft-start normally closed relay Relay31.

[0068] When the bus capacitor soft-starts to the peak value of the input phase voltage, all main relays Relay1, Relay2 and Relay3 are energized, and the soft-start normally closed relays Relay11, Relay21 and Relay31 are disconnected. Then, the AC to DC conversion is completed through the three-phase four-bridge-arm PWM converter.

[0069] When reversely inverting DC to AC conversion, first disconnect all relays. After the three-phase four-bridge arm PWM converter completes the software inverter soft start, when the inverter output amplitude and phase meet the output conditions, attract all main relays Relay1, Relay2 and Relay3 to realize DC to AC conversion.

[0070] When the three-phase AC power supply is a three-wire system, A, B and C are connected to the three-phase live wires respectively, and N is left floating. When working in the forward direction, the A phase forms a loop to soft-start the bus capacitor C4 through the soft-start resistor R1 and the soft-start normally closed relay Relay11, the B phase soft-start resistor R2 and the soft-start normally closed relay Relay21, and the C phase soft-start resistor R3 and the soft-start normally closed relay Relay31. When the bus capacitor soft-starts to the peak value of the input line voltage, all the main relays Relay1, Relay2 and Relay3 are attracted, and the soft-start normally closed relays Relay11, Relay21 and Relay31 are disconnected, and then the AC to DC conversion is completed through the three-phase four-bridge arm PWM converter.

[0071] When reversely inverting DC to AC conversion, first disconnect all relays. After the three-phase four-bridge arm PWM converter completes the software inverter soft start, when the inverter output amplitude and phase meet the output conditions, attract all main relays Relay1, Relay2 and Relay3 to realize DC to AC conversion.

Claims

1. A control method for a bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies, characterized in that: The bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies includes four wiring terminals, wherein the first wiring terminal, the second wiring terminal and the third wiring terminal are respectively connected to the corresponding midpoint of the first bridge arm of the power converter, the midpoint of the second bridge arm of the power converter and the midpoint of the third bridge arm of the power converter through the corresponding first inductor L1, the second inductor L2 and the third inductor L3, and the fourth wiring terminal is connected to the midpoint of the fourth bridge arm of the power converter, and the four power converter bridge arms are connected in parallel and in parallel with the bus capacitor C4; Also includes a first main switch device connected between the first wiring terminal and the first inductor L1, a second main switch device connected between the second wiring terminal and the second inductor L2, and a third main switch device connected between the third wiring terminal and the third inductor L3; The fourth terminal is connected to between the first main switch device and the first inductor L1, between the second main switch device and the second inductor L2, and between the third main switch device and the third inductor L3 through the first capacitor C1, the second capacitor C2 and the third capacitor C3 respectively; It also includes a fifth short-circuit switch device for connecting the first wiring terminal and the second wiring terminal, and a sixth short-circuit switch device for connecting the third wiring terminal and the fourth wiring terminal; one end of the fifth short-circuit switch device is connected to the first wiring terminal through the first main switch device, and the other end is connected to the second wiring terminal through the second main switch device; or the fifth short-circuit switch device is directly connected between the first wiring terminal and the second wiring terminal; one end of the sixth short-circuit switch device is connected to the third wiring terminal through the third main switch device, and the other end is directly connected to the fourth wiring terminal; or the sixth short-circuit switch device is directly connected between the third wiring terminal and the fourth wiring terminal; Or one end of the sixth short-circuit switch device is connected to the third terminal through the third inductor L3 and the third main switch device, and the other end is connected to the fourth terminal through the fourth inductor L4; the fourth terminal is connected to the midpoint of the fourth bridge arm of the power converter through the fourth inductor L4; The control method comprises the following steps: When working in the forward direction, firstly, the soft-start circuit is turned on, and the wiring terminal connected to the soft-start circuit is connected to the bus capacitor C4, and the bus capacitor C4 is soft-started. After the soft-start, the switch device between the wiring terminal connected to the AC power supply and the bus capacitor C4 is turned on, and then the soft-start circuit is turned off to complete the AC to DC conversion through the power converter; During reverse inversion, when the AC power source type is three-phase AC, first disconnect all switch devices, and after the power converter completes the software inversion soft start, when the inverter output amplitude and phase meet the output conditions, connect the main switch device between the terminal connected to the AC power source and the bus capacitor C4 to achieve DC to AC conversion; or During reverse inversion, when the AC power supply type is single-phase AC, first, the short-circuit relay and all the main switching devices in the loop from the fourth terminal to the midpoint of the third bridge arm and the midpoint of the fourth bridge arm are energized, and the remaining switching devices are disconnected. After the power converter completes the software inverter soft start, when the inverter output amplitude and phase meet the output conditions, all the main switching devices in the loop from the first terminal to the midpoint of the first bridge arm and the midpoint of the second bridge arm are energized to achieve DC to AC conversion.

2. The control method of a bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies according to claim 1, characterized in that: The first main switch device is connected in parallel with a first soft-start circuit, the second main switch device is connected in parallel with a second soft-start circuit, and the third main switch device is connected in parallel with a third soft-start circuit.

3. A bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies according to claim 1, characterized in that: The first main switch device is connected in parallel with a first soft-start circuit, the second main switch device is connected in parallel with a second soft-start circuit, and the third main switch device is connected in parallel with a third soft-start circuit.

4. The control method of a bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies according to claim 1, characterized in that: The first connecting terminal, the second connecting terminal, the third connecting terminal and the fourth connecting terminal are respectively an A-phase connecting terminal, a B-phase connecting terminal, a C-phase connecting terminal and an N-phase connecting terminal.

5. The control method of a bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies according to claim 1, characterized in that: When the AC power supply is three-phase AC power, the connection method between the terminal block and the AC power supply is a three-phase four-wire system or a three-phase three-wire system.

6. The control method of a bidirectional ACDC circuit compatible with three-phase and single-phase AC power supplies according to claim 1, characterized in that: The switch device comprises a main switch device and a short switch device.

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