JP2013090499A - Bidirectional chopper circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-efficient bidirectional chopper circuit that has a low cost and simple configuration and allows achieving, for example, improvement of fuel consumption of a vehicle.SOLUTION: A bidirectional chopper circuit 1 includes: a main reactor 12 connected to a terminal T11; switches 13 and 14 that are connected between terminals T21 and T22 and in which the main reactor 12 is connected to their connection point P1; an auxiliary reactor 16 connected between the terminal T11 and the main reactor 12; and an auxiliary circuit 17 that has a serial connection body of a capacitor 21 and a diode 22 provided corresponding to either one of the switches 13 and 14 and connected in parallel to the corresponding switch, and an auxiliary switch 24 connected between a connection point P2 of the capacitor 21 and the diode 22 constituting the series connection body and a connection point P3 of the main reactor 12 and the auxiliary reactor 16.

Description

  The present invention relates to a bidirectional chopper circuit.

  In recent years, in order to realize a low-carbon society, research on hybrid vehicles (HV: Hybrid Vehicle) using both an engine and a motor as a power generation source and electric vehicles (EV: Electric Vehicle) using only a motor as a power generation source has been active. Has been done. Such hybrid vehicles and electric vehicles include a battery such as a rechargeable lithium ion secondary battery that supplies electric power for driving a motor, a chopper circuit that converts the voltage of the battery, and a voltage converted by the chopper circuit. And a drive circuit such as an inverter for driving the motor using the motor.

  Here, in order to effectively use energy, a vehicle such as a hybrid vehicle or an electric vehicle uses a motor as a regenerative brake to charge a battery with electric power generated by the motor. For this reason, in the above vehicle, as the above chopper circuit, for example, the voltage of electric power (forward power) supplied from the battery to the motor is boosted, and electric power generated by the motor and collected in the battery (reverse) A bidirectional chopper circuit is used to step down the voltage of the direction power).

  The bidirectional chopper circuit provided in the above vehicle is required to have a small size, high efficiency, and high output. In recent years, as a highly efficient chopper circuit using soft switching technology, a SAZZ (Snubber Assisted Zero Voltage and Zero Current Transition) chopper circuit has been proposed. Here, the soft switching technique is a technique for reducing power loss by performing a switching operation in a state where the voltage or current is zero using a resonance phenomenon or the like, and the SAZZ chopper circuit is This is a chopper circuit that realizes soft switching using a snubber circuit.

  In Patent Document 1 below, a resonant capacitor is connected in parallel between the collector and emitter of a transistor that performs a switching operation, and when the charge of the resonant capacitor becomes zero, the transistor is turned on and soft switching is performed at zero voltage. A buck-boost chopper circuit to perform is disclosed. Patent Document 2 below discloses a bidirectional step-up / step-down chopper circuit to which the SAZZ chopper circuit is applied.

Japanese Patent No. 4390256 JP 2007-274778 A

  By the way, the chopper circuit using the soft switching technology disclosed in the above-mentioned Patent Documents 1 and 2 has an extremely excellent advantage that high efficiency can be obtained, and will be applied to vehicles such as hybrid cars and electric cars in the future. It is expected to be installed. However, such a chopper circuit has a problem in that the circuit configuration is complicated and the number of parts increases, so that the cost increases and it is extremely difficult to make it into a product.

  Here, a bidirectional chopper capable of converting both the voltage of power (forward power) supplied from the battery to the motor and the voltage of power generated by the motor and collected by the battery (reverse power). In the circuit, it is considered that the higher conversion efficiency of power in the reverse direction than that in the forward direction greatly contributes to the improvement of fuel consumption of the vehicle. The reason is that more energy released mainly as heat can be reused as more electrical energy.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a high-efficiency bidirectional chopper circuit that has an inexpensive and simple configuration and can improve the fuel consumption of a vehicle, for example. .

In order to solve the above problems, a bidirectional chopper circuit according to the present invention includes a reactor (12) connected to a first input / output terminal (T11, T12) and a second input / output terminal (T21, T22). In a bidirectional chopper circuit (1) comprising first and second switches (13, 14) connected in series and having the reactor connected to a connection point (P1), the first input / output terminal and the reactor A series of an auxiliary reactor (16) connected in between and a capacitor (21) and a diode (22) provided corresponding to one of the first and second switches and connected in parallel to the corresponding switch A connection body, and an auxiliary switch (24) connected between a connection point (P2) of the capacitor and the diode forming the series connection body and a connection point (P3) of the reactor and the auxiliary reactor. It is characterized in that it comprises an auxiliary circuit (17).
The bidirectional chopper circuit of the present invention is a switch that is driven when the first switch supplies power from the first input / output end side to the second input / output end side, and the second switch Is a switch that is driven when power is supplied from the second input / output end side to the first input / output end side.
The bidirectional chopper circuit according to the present invention is characterized in that the second input / output terminal is arranged on a higher voltage side than the first input / output terminal.
In the bidirectional chopper circuit of the present invention, the auxiliary circuit is provided corresponding to the second switch when the battery (56) for collecting electric power is connected to the first input / output terminal side. In the case of being connected to the second input / output terminal side, it is provided corresponding to the first switch.
The bidirectional chopper circuit of the present invention is characterized in that the first and second switches are insulated gate bipolar transistors with antiparallel diodes.
Further, the bidirectional chopper circuit of the present invention includes a first capacitor (11) connected between the first input / output terminals and a second capacitor (15) connected between the second input / output terminals. It is characterized by that.

  According to the present invention, the auxiliary reactor is connected between the first input / output terminal and the reactor, and the auxiliary circuit for soft-switching the switch is provided corresponding to one of the first and second switches. There is an effect that a bidirectional chopper circuit having a simple configuration and high efficiency can be realized.

1 is a circuit diagram illustrating a bidirectional chopper circuit according to an embodiment of the present invention. FIG. 3 is a circuit diagram in which configurations that contribute to boosting and step-down operations of a bidirectional chopper circuit according to an embodiment of the present invention are extracted. It is a figure which shows the state which applied the chopper circuit by one Embodiment of this invention to the vehicle. It is a figure which shows the state which applied the chopper circuit by one Embodiment of this invention to the vehicle.

  Hereinafter, a bidirectional chopper circuit according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit diagram showing a bidirectional chopper circuit according to an embodiment of the present invention. As shown in FIG. 1, the bidirectional chopper circuit 1 of this embodiment includes terminals T11 and T12 (first input / output terminals) and terminals T21 and T22 (second input / output terminals), and converts the voltage. DC power is supplied from the terminals T11 and T12 to the terminals T21 and T22, or from the terminals T21 and T22 to the terminals T11 and T12.

  Specifically, in the bidirectional chopper circuit 1 shown in FIG. 1, the terminals T21 and T22 are arranged on the higher voltage side than the terminals T11 and T12, and the voltage of the DC power supplied between the terminals T11 and T12 is boosted. Output from the terminals T21, T22, or step down the voltage of the DC power supplied between the terminals T21, T22 and output from the terminals T11, T12. In the present embodiment, a battery is connected between the terminals T11 and T12, and a load is connected between the terminals T21 and T22. Further, in FIG. 1, a control device that controls the operation of the bidirectional chopper circuit 1 is not shown.

  As shown in FIG. 1, the bidirectional chopper circuit 1 includes a capacitor 11 (first capacitor), a main reactor 12 (reactor), a switch 13 (first switch), a switch 14 (second switch), and a capacitor 15 (second capacitor). ), An auxiliary reactor 16, and an auxiliary circuit 17. The capacitor 11 is connected between the terminals T11 and T12, and smoothes the power supplied from the terminals T21 and T22 and output from the terminals T11 and T12 to obtain DC power. The capacitor 11 also removes noise superimposed on the DC power supplied from the terminals T11 and T12 side.

  The main reactor 12 is connected between the terminal T11 and the connection point P1 of the switches 13 and 14, and stores and discharges electric power according to the switching operation of the switches 13 and 14 and the like. The switch 13 is a switch that is driven when the voltage of the DC power supplied between the terminals T11 and T12 is boosted and output from the terminals T21 and T22. On the other hand, the switch 14 is a switch that is driven when the voltage of the DC power supplied between the terminals T21 and T22 is stepped down and output from the terminals T11 and T12.

  These switches 13 and 14 are connected in series between terminals T21 and T22, and are realized by, for example, an IGBT (Insulated Gate Bipolar Transistor) with an antiparallel diode. As the switches 13 and 14, other than the IGBT, a normal bipolar transistor or an FET transistor (Field Effect Transistor) can be used. These switches 13 and 14 are controlled by the control device (not shown) described above, and are driven at a switching frequency of about 100 kHz, for example.

  The capacitor 15 is connected between the terminals T21 and T22, and smoothes the power supplied from the terminals T11 and T12 and output from the terminals T21 and T22 to obtain DC power. The capacitor 15 also removes noise superimposed on the DC power supplied from the terminals T21 and T22 side. The auxiliary reactor 16 is connected between the terminal T11 and the main reactor 12, and stores power according to the switching operation of the switches 13, 14 and the auxiliary switch 24 (details will be described later) provided in the auxiliary circuit 17. Release.

  The auxiliary circuit 17 is provided corresponding to the switch 14 and is a circuit that realizes soft switching of the switch 14 together with the main reactor 12 and the auxiliary reactor 16. The auxiliary circuit 17, the main reactor 12, the auxiliary reactor 16, and the switch 14 form a SAZZ chopper circuit. Here, providing the auxiliary circuit 17 corresponding to only the switch 14 of the switches 13 and 14 supplies power from the terminals T21 and T22 to the terminals T11 and T12 while realizing an inexpensive and simple configuration. This is to perform the above efficiently.

  As described above, since the auxiliary circuit 17 is a circuit that realizes soft switching of the corresponding switch, it can be provided corresponding to each of the switches 13 and 14. If the auxiliary circuit 17 is provided corresponding to each of the switches 13 and 14, power supply from the terminal T11, T12 side to the terminal T21, T22 side and power supply from the terminal T21, T22 side to the terminal T11, T12 side Both of these can be performed efficiently.

  However, if the auxiliary circuit 17 is provided corresponding to each of the switches 13 and 14, the circuit configuration of the bidirectional chopper circuit 1 becomes complicated and the number of parts increases, resulting in an increase in cost. Therefore, in this embodiment, an inexpensive and simple configuration is achieved while improving the efficiency of power supply from the terminals T21 and T22 to the terminals T11 and T12 (power supply to the battery connected between the terminals T11 and T12). Therefore, the auxiliary circuit 17 is provided corresponding to only the switch 14.

  The auxiliary circuit 17 includes a capacitor 21, a diode 22, a diode 23, and an auxiliary switch 24. The capacitor 21 and the diode 22 are connected in series and are connected in parallel to the switch 14. The series connection body of the capacitor 21 and the diode 22 is a protection circuit provided to absorb an excessively high voltage generated by the switching operation of the switch 14. That is, the capacitor 21 is a snubber capacitor, and the diode 22 is a snubber diode.

  The diode 23 and the auxiliary switch 24 are connected in series, and are connected between a connection point P2 between the capacitor 21 and the diode 22 and a connection point P3 between the main reactor 12 and the auxiliary reactor 16. The diode 23 has an anode electrode connected to the auxiliary switch 24 and a cathode electrode connected to a connection point P <b> 2 between the capacitor 21 and the diode 22. The auxiliary switch 24 is realized by, for example, an IGBT with an antiparallel diode. As the auxiliary switch 24, as with the switches 13 and 14, other than the IGBT, a normal bipolar transistor or an FET transistor can be used.

  Next, the operation of the bidirectional chopper circuit 1 having the above configuration will be described. FIG. 2 is a circuit diagram in which configurations contributing to the boosting operation and the step-down operation of the bidirectional chopper circuit according to the embodiment of the present invention are extracted, respectively, and (a) is a circuit diagram illustrating the configuration contributing to the boosting operation. FIG. 6B is a circuit diagram showing a configuration that contributes to the step-down operation. Hereinafter, the step-up operation and the step-down operation will be described in order.

<Boosting operation>
During the boosting operation, only the switch 13 is driven by a control device (not shown), and the switch 14 and the auxiliary switch 24 are not driven and are turned off. For this reason, the bidirectional chopper circuit 1 is represented by the circuit shown in FIG. As shown in FIG. 2A, in the bidirectional chopper circuit 1, the auxiliary reactor 16, the main reactor 12, and the diode (switch 14) are sequentially connected between the terminal T11 and the terminal T21 during the boost operation. In this circuit, the switch 13 is connected between the point P1 and the terminals T12 and T22.

  Here, in this embodiment, since the switch 14 is realized by an IGBT with an antiparallel diode, when the IGBT is turned off by a control device (not shown), the IGBT is turned off and functions as a diode. Become. For this reason, in FIG. 2A, the switch 14 is illustrated as a diode. A capacitor 11 is connected between the terminals T11 and T12, and a capacitor 15 is connected between the terminals T21 and T22.

  In the circuit shown in FIG. 2A, when the auxiliary reactor 16 and the main reactor 12 are regarded as one reactor, the voltage appearing at the terminals T11 and T12 is boosted by switching the switch 13 (hard switching). This is a typical step-up chopper circuit that outputs from T21 and T22. For this reason, when the switch 13 is driven by a control device (not shown), for example, DC power supplied from a battery connected to the terminals T11 and T12 is boosted and output from the terminals T21 and T22.

<Step-down operation>
During the step-down operation, the switch 14 and the auxiliary switch 24 are driven by a control device (not shown), and the switch 13 is not driven and is turned off. For this reason, the bidirectional chopper circuit 1 is represented by a circuit shown in FIG. As shown in FIG. 2B, in the bidirectional chopper circuit 1, the switch 14, the main reactor 12, and the auxiliary reactor 16 are sequentially connected between the terminal T21 and the terminal T11 during the step-down operation, and the connection point P1 A diode (switch 13) is connected between the terminals T12 and T22, and an auxiliary circuit 17 is provided corresponding to the switch 14.

  Here, in the present embodiment, since the switch 13 is also realized by an IGBT with an antiparallel diode, the IGBT is turned off and functions as a diode when turned off by a control device (not shown). become. Therefore, in FIG. 2B, the switch 13 is illustrated as a diode. A capacitor 11 is connected between the terminals T11 and T12, and a capacitor 15 is connected between the terminals T21 and T22.

  In the circuit shown in FIG. 2B, when the main reactor 12 and the auxiliary reactor 16 are regarded as one reactor without taking the auxiliary circuit 17 into consideration, the switch T14 is switched (hard switching), so that the terminals T21 and T22 are switched. Is a typical step-down chopper circuit that steps down the voltage appearing at the output terminal and outputs it from terminals T11 and T12. For this reason, when the switch 14 is driven by a control device (not shown), for example, the DC power supplied to the terminals T21 and T22 is stepped down and output from the terminals T11 and T12 and connected to the battery connected to the terminals T11 and T12. Will be supplied.

  The bidirectional chopper circuit 1 has a configuration in which an auxiliary circuit 17 for soft-switching the switch 14 is provided for the above typical step-down chopper circuit. In FIG. 2B, for simplicity of explanation and simplification of illustration, the diode 23 provided in the auxiliary circuit 17 and the diode connected in reverse parallel to the IGBT forming the auxiliary switch 24 are illustrated. Omitted.

  The operation of the bidirectional chopper circuit 1 shown in FIG. 2B includes six operation modes of first to sixth operation modes described below, and these first to sixth operation modes are repeated. The first operation mode is an operation mode in which, when the switch 14 is in an off state, the auxiliary switch 24 is in an on state and the carrier of the diode (switch 13) disappears. Before the auxiliary switch 24 is turned on, since the switch 14 is in the off state, the current flows through the main reactor 12, the auxiliary reactor 16, the battery connected between the terminals T11 and T12, and the diode 13 in order. Flowing.

  When the auxiliary switch 24 is turned on, current flows from the capacitor 11 to the capacitor 11 via the auxiliary reactor 16, the auxiliary switch 24, the diode 22, and the diode (switch 13) in this order. Thereby, the carriers of the diode (switch 13) disappear and the diode (switch 13) is turned off. During the first operation mode, the capacitor 21 is not discharged, and the voltage of the capacitor 21 is primarily kept constant.

  The second operation mode is an operation mode in which the capacitor 21 is discharged after the end of the first operation mode. When the first operation mode ends, the diode (switch 13) is turned off in addition to the switch 14. Then, a current flows in a path that reaches the capacitor 21 through the capacitor 21, the capacitor 15, the capacitor 11, the auxiliary reactor 16, and the auxiliary switch 24 in this order. Thereby, the capacitor 21 is discharged, and the voltage of the capacitor 21 goes to zero. In the second operation mode, the current flowing through the main reactor 12 is circulated through the auxiliary switch 24 and the diode 22.

  The third operation mode is an operation mode in which the switch 14 is turned on by soft switching after the end of the second operation mode. When the second operation mode ends, the voltage of the capacitor 21 becomes zero. At this timing, the switch 14 is turned on. When the switch 14 is turned on, a current in a direction from the terminal T11 to the terminal T11 flows through the switch.

  Here, in the third operation mode, since the switch 14 and the auxiliary switch 24 are on and the diode (switch 13) is off, the capacitor 11, the auxiliary reactor 16, the auxiliary switch 24, the diode 22, the switch 14, and A current flows through a path that reaches the capacitor 11 through the capacitor 15 in order. This current flows in a direction that cancels the current that originally flows through the switch 14 (current in the direction from the terminal T11 to the terminal T11). As a result, the switch 14 realizes ZCS (Zero Current Switching) in which the switching operation (turn-on) is performed in a state where the current is zero.

  The fourth operation mode is an operation mode in which the current flowing through the switch 14, the main reactor 12, and the auxiliary reactor 16 is increased after the end of the third operation mode. When the current flowing in the third operation mode described above (current flowing in the direction that cancels the current that originally flows through the switch 14) gradually decreases to zero, the diode 22 is turned off. Then, current begins to flow in a path from the capacitor 15 to the capacitor 15 through the switch 14, the main reactor 12, the auxiliary reactor 16, and the capacitor 11 in this order.

  The fifth operation mode is an operation mode in which the switch 14 and the auxiliary switch 24 are turned off by soft switching after the end of the fourth operation mode. The switch 14 realizes ZVS (Zero Voltage Switching) in which the switching operation (turn-off) is performed when the voltage of the capacitor 21 is zero, and the auxiliary switch 14 performs the switching operation (turn-off) in a state where the current is zero. ZCS is realized. When the switch 14 and the auxiliary switch 24 are turned off, a current flows through a path that reaches the capacitor 11 through the capacitor 11, the capacitor 15, the capacitor 21, the diode 22, the main reactor 12, and the auxiliary reactor 16 in this order.

  In the sixth operation mode, after the end of the fifth operation mode, the diode (switch 13) is turned on, and the electric power stored in the main reactor 12 and the auxiliary reactor 16 is output from the terminals T11, T12, and the terminals T11, T12, This is an operation mode to be supplied to the battery connected to T12. When the diode (switch 13) is turned on, a current flows through a path sequentially passing through the main reactor 12 and the auxiliary reactor 16, the battery connected between the terminals T11 and T12, and the diode 13.

  As described above, in this embodiment, the bidirectional reactor includes the main reactor 12 connected to the terminal T11 and the switches 13 and 14 connected in series between the terminals T21 and T22 and connected to the connection point P1. In the chopper circuit, an auxiliary reactor 16 is connected between the terminal T11 and the main reactor 12, and an auxiliary circuit 17 for soft-switching the switch 14 is provided corresponding to the switch 14. For this reason, DC power can be efficiently supplied to the battery connected between the terminals T21 and T22 with an inexpensive and simple configuration.

  3 and 4 are views showing a state in which the chopper circuit according to one embodiment of the present invention is applied to a vehicle. Here, an example applied to a hybrid vehicle will be described. As shown in FIGS. 3 and 4, the vehicle 50 includes an engine 51, a motor 52, a drive shaft 53, a differential gear 54, and a tire 54, and transmits the rotational driving force of the engine 51 and the motor 52 to the drive shaft 53. Then, the rotational driving force transmitted to the drive shaft 53 is converted by the differential gear 54 to drive the tire 55.

  The vehicle 50 includes a battery 56, a bidirectional chopper circuit 1, and an inverter 57 for driving the motor 52. The battery 56 is a rechargeable lithium ion secondary battery that supplies power for driving the motor 52, and is connected between the terminals T <b> 11 and T <b> 12 of the chopper circuit 1. The bidirectional chopper circuit 1 is the circuit described with reference to FIGS. 1 and 2, boosts the DC power from the battery 56 and supplies the boosted DC power to the inverter 57, and steps down the DC power from the inverter 57. To supply.

  The inverter 57 is a circuit that converts DC power supplied from the battery 56 into three-phase AC power and drives the motor 52, and is connected between the terminals T <b> 21 and T <b> 22 of the chopper circuit 1. The inverter 57 can also convert the three-phase AC power generated by the motor 52 into DC power and supply it to the bidirectional chopper circuit 1. The inverter 57 is controlled by a control device (not shown).

  In the above configuration, for example, when the accelerator pedal is depressed by the driver, the bidirectional chopper circuit 1 is controlled by a control device (not shown), and the DC power from the battery 56 is boosted by the bidirectional chopper circuit 1 as shown in FIG. And supplied to the inverter 57. The DC power supplied to the inverter 57 is converted into three-phase AC power under the control of a control device (not shown) and supplied to the motor 52. Thereby, the motor 52 is driven, the rotational driving force is transmitted through the drive shaft 53 and the differential gear 54, and the tire 55 is driven.

  On the other hand, for example, when the brake pedal is depressed by the driver, the inverter 57 is controlled by a control device (not shown), the motor 52 operates as a regenerative brake, and the AC power generated by the motor 52 is converted to DC power by the inverter 57. And is supplied to the bidirectional chopper circuit 1. Then, the bidirectional chopper circuit 1 is controlled by a control device (not shown), and the DC power supplied to the bidirectional chopper circuit 1 is increased in voltage and supplied to the battery 56 as shown in FIG. Is done.

  Here, in the present embodiment, when the electric power recovered from the motor 52 operating as a regenerative brake is supplied to the battery 56, the switch 14 is soft-switched by the auxiliary circuit 17 in the bidirectional chopper circuit 1. For this reason, compared with the case where the switch 14 is hard-switched, the electric power generated by the motor 52 can be efficiently collected, so that the fuel efficiency of the vehicle 50 can be improved.

  The bidirectional chopper circuit according to the embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and can be freely changed within the scope of the present invention. For example, in the above-described embodiment, the example in which the auxiliary circuit 17 is provided corresponding to only the switch 14 of the switches 13 and 14 has been described. However, the auxiliary circuit 17 may be provided only to the switch 13. Here, considering the energy recovery efficiency to the battery 56, when the battery 56 is connected to the terminals T11 and T12 arranged on the low voltage side, the auxiliary circuit 17 is provided corresponding to the switch 14, and the battery 56 When connected to terminals T21 and T22 arranged on the high voltage side, it is desirable to provide an auxiliary circuit 17 corresponding to the switch 13.

  In the above embodiment, the case where the vehicle is a hybrid vehicle has been described as an example. However, the present invention can be generally applied to a vehicle including a rechargeable battery and a motor as a power generation source that generates power by electric power supplied from the battery. For example, in addition to the above hybrid vehicle, the present invention can be applied to vehicles such as electric vehicles and electric heavy machinery.

DESCRIPTION OF SYMBOLS 1 Bidirectional chopper circuit 11,15 Capacitor 12 Main reactor 13,14 Switch 16 Auxiliary reactor 17 Auxiliary circuit 21 Capacitor 22 Diode 24 Auxiliary switch 56 Battery P1, P2, P3 Connection point T11, T12 terminal T21, T22 terminal

Claims (6)

In a bidirectional chopper circuit comprising a reactor connected to a first input / output terminal, and first and second switches connected in series between a second input / output terminal and the reactor connected to a connection point,
An auxiliary reactor connected between the first input / output end and the reactor;
A series connection body of a capacitor and a diode provided corresponding to one of the first and second switches and connected in parallel to the corresponding switch, and a connection point between the capacitor and the diode forming the series connection body, A bidirectional chopper circuit comprising: an auxiliary circuit having an auxiliary switch connected between the reactor and a connection point of the auxiliary reactor. The first switch is a switch that is driven when power is supplied from the first input / output end side to the second input / output end side;
The bidirectional chopper circuit according to claim 1, wherein the second switch is a switch that is driven when power is supplied from the second input / output end side to the first input / output end side.   The bidirectional chopper circuit according to claim 1, wherein the second input / output terminal is disposed on a higher voltage side than the first input / output terminal.   The auxiliary circuit is provided corresponding to the second switch when a battery for recovering power is connected to the first input / output end side, and is connected to the second input / output end side. The bidirectional chopper circuit according to claim 1, wherein the bidirectional chopper circuit is provided corresponding to the first switch.   The bidirectional chopper circuit according to any one of claims 1 to 4, wherein the first and second switches are insulated gate bipolar transistors with antiparallel diodes. A first capacitor connected between the first input / output terminals;
The bidirectional chopper circuit according to claim 1, further comprising: a second capacitor connected between the second input / output terminals.

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