Charging device

Abstract

To provide a charging device that can continue charging of a storage battery without stopping charging operation before completion of charging by overcharge by a capacitor.SOLUTION: A charging device includes a capacitor unit having a first capacitor and a second capacitor connected in series between a positive electrode side terminal and a negative electrode side terminal of a storage battery, a power converter having a three-level inverter connected in parallel to the storage battery, a control device that controls to switch on and off of each switching element, a first connection terminal connected to a P terminal of a charger between a first switching element and a second switching element of any one phase among three phases, and a second connection terminal connected to an N terminal of the charger between a third switching element and a fourth switching element of another phase. A balancer circuit that is connected in parallel between the storage battery and the capacitor unit and that transfers charges from one capacitor to the other capacitor when the voltage of the one capacitor is more than a predetermined threshold is provided.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a charging device.

Background Art

[0002] Patent Document 1 discloses a power supply device that also functions as a charging device capable of charging a storage battery by a DC charger, having a first connection terminal connected to a P terminal of the DC charger between a first switching element and a second switching element of any one of three phases, and a second connection terminal connected to an N terminal of the DC charger between a third switching element and a fourth switching element of another one of the three phases.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] During charging of a storage battery by a DC charger, if the voltages of two smoothing capacitors in series connection, which are connected in parallel to the storage battery, become unbalanced, the capacitors may be overcharged, and it is necessary to stop the charging operation before the charging of the storage battery is completed, so there is room for improvement.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a charging device capable of continuing charging of a storage battery without stopping the charging operation before completion of charging due to overcharging of a capacitor.

Means for Solving the Problems

[0006] In order to solve the above-described problems and achieve the object, a charging device according to the present invention includes a capacitor unit in which a first capacitor and a second capacitor are connected in series between a positive electrode terminal and a negative electrode terminal of a storage battery, a first switching element, a second switching element, a third switching element, and a fourth switching element connected in series, a first diode having a cathode side connected to a wiring connecting the first switching element and the second switching element and an anode side connected to a wiring connecting the first capacitor and the second capacitor, and a second diode having an anode side connected to a wiring connecting the third switching element and the fourth switching element and a cathode side connected to a wiring connecting the first capacitor and the second capacitor. By turning on and off the first switching element, the second switching element, the third switching element, and the fourth switching element respectively, a three-level inverter capable of selectively outputting a voltage of any one of three different voltage values to a motor generator is connected in parallel with the storage battery for three phases of U-phase, V-phase, and W-phase, a power converter, a control device for controlling switching between on and off of each switching element of the power converter, a first connection terminal electrically connected to a P terminal of a DC charger between the first switching element and the second switching element in the three-level inverter of any one of the U-phase, the V-phase, and the W-phase, and a second connection terminal electrically connected to an N terminal of the DC charger between the third switching element and the fourth switching element in the three-level inverter of another one of the U-phase, the V-phase, and the W-phase. A charging device is provided, and between the storage battery and the capacitor unit, there is a balancer circuit connected in parallel with the storage battery and the capacitor unit, and when the voltage of one of the first capacitor and the second capacitor exceeds a preset threshold value, the balancer circuit moves charges from the one capacitor to the other capacitor.

[0007] In the charging device according to the present invention, during charging of the storage battery by the DC charger, by moving the charge from one capacitor exceeding the threshold value to the other capacitor by the balancer circuit, the voltage of the one capacitor can be decreased. Therefore, in the charging device according to the present invention, it is possible to suppress the voltage of the one capacitor from reaching the capacitor upper limit voltage and continue the charging operation until the storage battery is fully charged.

[0008] Also, in the above, the balancer circuit is composed of a first balancer switching element, a second balancer switching element, and a reactor. The first balancer switching element and the second balancer switching element are connected in series between the positive terminal and the negative terminal of the storage battery. One side of the reactor is connected between the first balancer switching element and the second balancer switching element, and the other side of the reactor is connected between the first capacitor and the second capacitor. The control device may control the switching between on and off of the first balancer switching element and the second balancer switching element based on the voltage of the first capacitor or the second capacitor.

[0009] Thereby, based on the voltage of the first capacitor or the second capacitor, the control device switches between on and off of the first balancer switching element and the second balancer switching element of the balancer circuit, so that the charge can be moved from the one capacitor to the other capacitor via the reactor.

[0010] Also, in the above, when the voltage of the first capacitor exceeds the threshold value, the control device may turn on the first balancer switching element and turn off the second balancer switching element, and then turn off the first balancer switching element and turn on the second balancer switching element at a predetermined timing.

[0011] As a result, part of the charge of the first capacitor is accumulated in the reactor, causing the voltage of the first capacitor to drop. Subsequently, the charge of the first capacitor accumulated in the reactor moves to the second capacitor, increasing the voltage of the second capacitor. Therefore, the voltage imbalance between the first capacitor and the second capacitor can be reduced.

[0012] Also, in the above, when the voltage of the second capacitor exceeds the threshold value, the control device turns on the second balancing switching element and turns off the first balancing switching element. Then, at a predetermined timing, the control device may turn off the second balancing switching element and turn on the first balancing switching element.

[0013] As a result, part of the charge of the second capacitor is accumulated in the reactor, causing the voltage of the second capacitor to drop. Subsequently, the charge of the second capacitor accumulated in the reactor moves to the first capacitor, increasing the voltage of the first capacitor. Therefore, the voltage imbalance between the first capacitor and the second capacitor can be reduced.

Advantages of the Invention

[0014] The charging device according to the present invention has the effect that it can continue charging the storage battery without stopping the charging operation before the completion of charging due to overcharging of the capacitor.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the charging device according to the present invention will be described. Note that the present invention is not limited by this embodiment.

[0017] FIG. 1 is a configuration diagram of a power system according to an embodiment. The power system according to the embodiment is applied to an electric vehicle such as an electric vehicle, a hybrid vehicle, a PHEV (Plug-in Hybrid Electric Vehicle), or a REEV (Range Extended Electric Vehicle) that can travel using electric power.

[0018] The power system according to the embodiment includes a charging device 10, a motor generator 20, a DC charger 30, and the like. Among the power system according to the embodiment, the charging device 10 and the motor generator 20 are mounted on the electric vehicle, and the DC charger 30 is provided in an external charging facility installed outside the electric vehicle.

[0019] The charging device 10 includes a battery 12, a capacitor unit 16, an inverter 18, a balancer circuit 26, a charging relay device 40, an ECU (Electronic Control Unit) 60, and the like. Note that the charging device 10 is electrically connected to the motor generator 20 and also functions as a power supply device that supplies power from the battery 12 to the motor generator 20.

[0020] The battery 12 is a rechargeable battery that can be charged and discharged as a high-voltage battery. As the battery 12, for example, in addition to a lithium-ion battery pack and a nickel-metal hydride battery pack, a nickel-cadmium battery, a lead storage battery, etc. can be used. In FIG. 1, "VB" is the battery voltage. As the battery voltage of the battery 12, it is desirable to be, for example, 400 [V] or more.

[0021] The capacitor unit 16 is composed of a first capacitor C1 and a second capacitor C2 that are connected in series with each other between the positive electrode terminal (positive bus bar 22) of the battery 12 and the negative electrode terminal (negative bus bar 24) of the battery 12. The first capacitor C1 and the second capacitor C2 are connected to each other at the neutral point NP1. That is, for the first capacitor C1, one terminal is connected to the positive bus bar 22 and the other terminal is connected to the neutral point NP1. Also, for the second capacitor C2, one terminal is connected to the neutral point NP1 and the other terminal is connected to the negative bus bar 24. Therefore, if the first capacitor C1 and the second capacitor C2 perform charge and discharge in the same way and always accumulate the same charge, the neutral point voltage, which is the voltage between the neutral point NP1 and the negative bus bar 24, will be clamped to half of the voltage of the battery 12. Note that the neutral point voltage corresponds to the voltage VC2, which is the voltage between the terminals of the second capacitor C2. Also, VC1 in FIG. 1 is the voltage between the terminals of the first capacitor C1.

[0022] The inverter 18 is a power converter and is composed of an upper arm to which a positive-side voltage, which is the voltage between the positive bus bar 22 and the neutral point NP1, is supplied, and a lower arm to which a negative-side voltage, which is the voltage between the neutral point NP1 and the negative bus bar 24, is supplied. In the inverter 18, the upper arm and the lower arm are arranged in series and multiplexed between the positive bus bar 22 and the negative bus bar 24, and it is possible to output a three-level three-phase AC voltage to the motor generator 20.

[0023] The inverter 18 also includes a U-phase arm that outputs a U-phase voltage to the motor generator 20, a V-phase arm that outputs a V-phase voltage to the motor generator 20, and a W-phase arm that outputs a W-phase voltage to the motor generator 20.

[0024] In the U-phase arm, the first switching element SU1, the second switching element SU2, the third switching element SU3, and the fourth switching element SU4 are connected in series in this order from the positive bus 22 toward the negative bus 24. The first switching element SU1, the second switching element SU2, the third switching element SU3, and the fourth switching element SU4 are configured such that a freewheeling diode is connected in anti-parallel to the semiconductor element. Note that reverse connection means, for example, that the cathode terminal of the diode is connected to the collector terminal of the semiconductor element and the anode terminal of the diode is connected to the emitter terminal of the semiconductor element. An intermediate point PU1 (first intermediate point) as a connection part in the wiring connecting the first switching element SU1 and the second switching element SU2, and an intermediate point PU2 (second intermediate point) as a connection part in the wiring connecting the third switching element SU3 and the fourth switching element SU4 are connected by diodes DU1 and DU2 such that the anode sides of the two series-connected diodes DU1 and DU2 are connected to the intermediate point PU2 and the cathode sides are connected to the intermediate point PU1. A connection point in the wiring connecting the two diodes DU1 and DU2 is connected to the neutral point NP1 of the capacitor unit 16. In other words, the diode DU1 has its cathode side connected to the intermediate point PU1 and its anode side connected to the neutral point NP1. Also, the diode DU2 has its anode side connected to the intermediate point PU2 and its cathode side connected to the neutral point NP1. In such a configuration, a U-phase voltage is output from the connection point between the second switching element SU2 and the third switching element SU3 to the motor generator 20.

[0025] In the V-phase arm, the first switching element SV1, the second switching element SV2, the third switching element SV3, and the fourth switching element SV4 are connected in series in this order from the positive busbar 22 toward the negative busbar 24. The first switching element SV1, the second switching element SV2, the third switching element SV3, and the fourth switching element SV4 are configured such that a freewheeling diode is connected in anti-parallel to the semiconductor element. An intermediate point PV1 (first intermediate point) as a connection part in the wiring connecting the first switching element SV1 and the second switching element SV2, and an intermediate point PV2 (second intermediate point) as a connection part in the wiring connecting the third switching element SV3 and the fourth switching element SV4 are connected by diodes DV1 and DV2 such that the anode sides of the two series-connected diodes DV1 and DV2 are connected to the intermediate point PV2 and the cathode sides are connected to the intermediate point PV1. A connection point in the wiring connecting the two diodes DV1 and DV2 is connected to the neutral point NP1 of the capacitor unit 16. In other words, the diode DV1 has its cathode side connected to the intermediate point PV1 and its anode side connected to the neutral point NP1. Also, the diode DV2 has its anode side connected to the intermediate point PV2 and its cathode side connected to the neutral point NP1. In such a configuration, the V-phase voltage is output from a connection point between the second switching element SV2 and the third switching element SV3 to the motor generator 20.

[0026] In the W-phase arm, the first switching element SW1, the second switching element SW2, the third switching element SW3, and the fourth switching element SW4 are connected in series in this order from the positive busbar 22 toward the negative busbar 24. The first switching element SW1, the second switching element SW2, the third switching element SW3, and the fourth switching element SW4 are configured such that a freewheeling diode is connected in anti-parallel to the semiconductor element. As an intermediate point PW1 (first intermediate point) as a connection part in the wiring connecting the first switching element SW1 and the second switching element SW2, and an intermediate point PW2 (second intermediate point) as a connection part in the wiring connecting the third switching element SW3 and the fourth switching element SW4 are connected by diodes DW1 and DW2 such that the anode sides of the two serially connected diodes DW1 and DW2 are connected to the intermediate point PW2 and the cathode sides are connected to the intermediate point PW1. A connection point in the wiring connecting the two diodes DW1 and DW2 is connected to the neutral point NP1 of the capacitor unit 16. In other words, for the diode DW1, the cathode side is connected to the intermediate point PW1 and the anode side is connected to the neutral point NP1. Also, for the diode DW2, the anode side is connected to the intermediate point PW2 and the cathode side is connected to the neutral point NP1. In such a configuration, a W-phase voltage is output from a connection point between the second switching element SW2 and the third switching element SW3 to the motor generator 20.

[0027] In the present embodiment, as each switching element of the inverter 18, an IGBT (Insulated Gate Bipolar Transistor) or the like can be used.

[0028] The motor generator 20 is a rotating electric machine mounted on the electric vehicle. When the DC voltage output from the battery 12 is converted into a three-phase AC voltage by the inverter 18 and supplied, the motor generator 20 acts as a motor and generates a driving force for running the vehicle. On the other hand, when the vehicle is braked, the motor generator 20 acts as a generator, recovers braking energy, and outputs it as a three-phase AC voltage. Then, this three-phase AC voltage is converted into a DC voltage by the inverter 18 and supplied to the battery 12, thereby charging the battery 12.

[0029] The DC charger 30 is an external charger provided outside the vehicle to charge the battery 12. The DC charger 30 has a P terminal (positive terminal) 32P and an N terminal (negative terminal) 32N, which are two terminals electrically connected to the charging device 10 side at a charger connection part 50 for connecting a plug (not shown) of the DC charger 30 and a connector (not shown) on the vehicle side. Between the charger connection part 50 and the inverter 18, a charging relay device 40 having a charging relay 42P and a charging relay 42N, and a reactor 44P are provided. Note that Vchg in FIG. 1 is the charger voltage.

[0030] As shown in FIG. 1, the P terminal 32P of the DC charger 30 is electrically connected to an intermediate point PV1 between the first switching element SV1 and the second switching element SV2 in the V-phase arm via the charging relay 42P and the reactor 44P. Also, the N terminal 32N of the DC charger 30 is electrically connected to an intermediate point PU2 between the third switching element SU3 and the fourth switching element SU4 in the U-phase arm via the charging relay 42N.

[0031] In the charging device 10 according to the embodiment, among the U-phase arm, the V-phase arm, and the W-phase arm, the intermediate points PU1, PV1, PW1, which are the first intermediate points in the three-level inverter of any one phase, are connected to the P terminal 32P of the DC charger 30, and the intermediate points PU2, PV2, PW2, which are the second intermediate points in the three-level inverter of the other one phase, are connected to the N terminal 32N of the DC charger 30.

[0032] As described above, in the charging device 10 according to the embodiment, among the U-phase arm, the V-phase arm, and the W-phase arm, the first midpoint in the three-level inverter of any one phase is used as the first connection terminal electrically connected to the P terminal 32P of the DC charger 30. Further, among the U-phase arm, the V-phase arm, and the W-phase arm, the second midpoint in the three-level inverter of the other one phase is used as the second connection terminal electrically connected to the N terminal 32N of the DC charger 30.

[0033] Then, the charging device 10 according to the embodiment electrically connects the P terminal 32P of the DC charger 30 at the first midpoint between the first switching element and the second switching element (the first midpoint) in the three-level inverter of any one phase among the U-phase, V-phase, and W-phase in the inverter 18, and electrically connects the N terminal 32N of the DC charger 30 at the second midpoint between the third switching element and the fourth switching element (the second midpoint) in the three-level inverter of the other one phase, so that the battery 12 can be charged by the DC charger 30 corresponding to a plurality of voltage standards. Further, in the charging device 10 according to the embodiment, since the DC charger 30 is connected to the existing terminal connecting the motor generator 20 and the inverter 18, it can be realized without processing the inverter 18 or adding internal wiring to the existing three-level inverter having a voltage dividing capacitor, so that the cost can be suppressed. Further, since a capacitor with a high withstand voltage and additional components are not required, the cost and the component size can be suppressed.

[0034] The balancer circuit 26 is connected in parallel between the battery 12 and the capacitor unit 16, and is composed of a first switching element SB1 which is a first balancer switching element, a second switching element SB2 which is a second balancer switching element, and a reactor 28.

[0035] The first switching element SB1 and the second switching element SB2 are connected in series with each other between the positive terminal (positive bus 22) of the battery 12 and the negative terminal (negative bus 24) of the battery 12. Also, the first switching element SB1 and the second switching element SB2 are connected to each other at the neutral point NP2. That is, one terminal of the first switching element SB1 is connected to the positive bus 22, and the other terminal is connected to the neutral point NP2. Also, one terminal of the second switching element SB2 is connected to the neutral point NP2, and the other terminal is connected to the negative bus 24.

[0036] One terminal of the reactor 28 is connected to the neutral point NP2, and the other terminal is connected to the neutral point NP1 of the capacitor unit 16.

[0037] The balancer circuit 26 is a circuit for eliminating the voltage imbalance between the first capacitor C1 and the second capacitor C2 of the capacitor unit 16 by switching the on and off states of the first switching element SB1 and the second switching element SB2.

[0038] FIG. 2 is a block diagram showing the configuration of the power system according to the embodiment. The ECU 60 is an electronic control unit that controls the operation of the charging device 10 and the like. The ECU 60 includes a charging control unit 62, a gate signal generation unit 64, and the like.

[0039] The charging control unit 62 receives various signals such as a charging power command signal output from a system control unit (not shown), a voltage phase signal output from a voltmeter (not shown) provided in the inverter 18, signals of the voltages VC1 and VC2 of the first capacitor C1 and the second capacitor C2 output from a voltmeter (not shown) provided in the capacitor unit 16, and a charger information signal output from the DC charger 30. Further, the charging control unit 62 outputs, for example, a duty obtained based on the charging power command signal, the voltage phase signal, and the signals of the voltages VC1 and VC2 to the gate signal generation unit 64. The gate signal generation unit 64 generates a gate signal for switching on and off each switching element of the inverter 18, and outputs the generated gate signal to each switching element. Also, the gate signal generation unit 64 generates a gate signal for switching on and off each switching element of the balancer circuit 26, and outputs the generated gate signal to each switching element.

[0040] Figure 3 is a diagram showing the circuit state when the battery 12 is charged by the DC charger 30. In FIG. 3, the switching elements in the on (ON) state are circled, and the switching elements in the off (OFF) state are not circled.

[0041] As shown in FIG. 3, when the battery 12 is charged by the DC charger 30, first, the ECU 60 switches the fourth switching element SU4 of the U-phase arm and the first switching element SW1 of the W-phase arm from off to on, and sets the other switching elements to the off state. Next, the ECU 60 switches the charging relays 42P and 42N of the charging relay device 40 from off to on, supplies a DC voltage from the DC charger 30 to the battery 12 via the inverter 18, and charges the battery 12.

[0042] Note that the fourth switching element SU4 and the first switching element SV1 may be turned off because current flows through their respective freewheeling diodes. As a result, all the switching elements of the inverter 18 are in the off state, so it is not necessary to perform a switching operation for switching on and off each switching element of the inverter 18, the charging efficiency can be increased, and the addition of inverter elements and a cooling mechanism for charging can be suppressed. On the other hand, by turning on the fourth switching element SU4 and the first switching element SV1, it becomes possible to ensure the durability when current flows through the fourth switching element SU4 and the first switching element SV1. Also, during charging, since the on and off of each switching element of the inverter 18 are fixed, the switching loss can be reduced.

[0043] FIG. 4 is a diagram showing voltage waveforms when the balancer circuit is not driven when a voltage imbalance occurs during charging.

[0044] When simply charging the battery 12 with the DC charger 30, due to the voltage imbalance between the first capacitor C1 and the second capacitor C2, the voltage of one capacitor may reach the capacitor upper limit voltage due to overcharging. When the voltage of one capacitor reaches the capacitor upper limit voltage in this way, in order to prevent the capacitor from being damaged, it is necessary to stop charging even though the charging of the battery 12 is not completed.

[0045] FIG. 5 is a diagram showing voltage waveforms when the balancer circuit is driven when a voltage imbalance occurs during charging.

[0046] In the charging device 10 according to the embodiment, during the charging of the battery 12 by the DC charger 30, when the voltage of one of the first capacitor C1 and the second capacitor C2 exceeds a preset threshold due to the voltage imbalance between the first capacitor C1 and the second capacitor C2, the balancer circuit 26 is driven. Note that the threshold is set to a voltage lower than the upper limit voltage of the capacitor preset to prevent the first capacitor C1 and the second capacitor C2 from being damaged.

[0047] In FIG. 5, when the voltage of the first capacitor C1 exceeds the threshold due to the voltage imbalance between the first capacitor C1 and the second capacitor C2, the balancer circuit 26 is driven to move the charge of the first capacitor C1 to the second capacitor C2, thereby reducing the voltage of the first capacitor C1 so that the voltage of the first capacitor C1 does not reach the upper limit voltage of the battery.

[0048] Hereinafter, with reference to FIGS. 6 and 7, a method of moving the charge of the first capacitor C1 to the second capacitor C2 by driving the balancer circuit 26 will be described.

[0049] FIG. 6 is a diagram showing the circuit state when the first switching element SB1 is turned on and the second switching element SB2 is turned off in the balancer circuit 26. FIG. 7 is a diagram showing the circuit state when the first switching element SB1 is turned off and the second switching element SB2 is turned on in the balancer circuit 26. Note that in FIGS. 6 and 7, attention is paid to the capacitor unit 16 and the balancer circuit 26 in the charging device 10 and they are illustrated.

[0050] First, as shown in FIG. 6, the ECU 60 turns on the first switching element SB1 and turns off the second switching element SB2 in the balancer circuit 26. As a result, a closed circuit is formed in which current flows through the first capacitor C1, the first switching element SB1, and the reactor 28 as indicated by arrow A in FIG. 6. At this time, a part of the charge of the first capacitor C1 is accumulated in the reactor 28, causing the voltage of the first capacitor C1 to drop. Thereafter, at a predetermined timing, as shown in FIG. 7, the ECU 60 turns off the first switching element SB1 and turns on the second switching element SB2 in the balancer circuit 26. As a result, a closed circuit is formed in which current flows through the second capacitor C2, the reactor 28, and the second switching element SB2 as indicated by arrow B in FIG. 7. At this time, the charge of the first capacitor C1 accumulated in the reactor 28 moves to the second capacitor C2, increasing the voltage of the second capacitor C2. Thereby, the voltage imbalance between the first capacitor C1 and the second capacitor C2 can be reduced.

[0051] Also, in the charging device 10 according to the embodiment, the ECU 60 repeatedly switches the first switching element SB1 and the second switching element SB2 in the balancer circuit 26 between on and off states, causing the charge of the first capacitor C1 to move to the second capacitor C2, thereby eliminating the voltage imbalance between the first capacitor C1 and the second capacitor C2.

[0052] Then, in the charging device 10 according to the embodiment, when the voltage of the first capacitor C1 exceeds the threshold value during the charging of the battery 12 by the DC charger 30, the balancer circuit 26 is driven to move the charge of the first capacitor C1 to the second capacitor C2, thereby suppressing the voltage of the first capacitor C1 from reaching the capacitor upper limit voltage. Therefore, the charging device 10 according to the embodiment can continue charging the battery 12 without stopping the charging operation before the completion of charging the battery 12 due to overcharging of the first capacitor C1.

[0053] Further, in the charging device 10 according to the embodiment, when the voltage of the second capacitor C2 exceeds the threshold value during charging of the battery 12 by the DC charger 30, the balancer circuit 26 is driven to move the charge of the second capacitor C2 to the first capacitor C1.

[0054] First, the ECU 60 turns on the second switching element SB2 and turns off the first switching element SB1 in the balancer circuit 26. Thereby, a closed circuit is formed such that current flows through the second capacitor C2, the reactor 28, and the second switching element SB2. At this time, a part of the charge of the second capacitor C2 is accumulated in the reactor 28, so that the voltage of the second capacitor C2 decreases. Thereafter, the ECU 60 turns off the second switching element SB2 and turns on the first switching element SB1 in the balancer circuit 26 at a predetermined timing. Thereby, a closed circuit is formed such that current flows through the first capacitor C1, the first switching element SB1, and the reactor 28. At this time, the charge of the second capacitor C2 accumulated in the reactor 28 moves to the first capacitor C1, so that the voltage of the first capacitor C1 increases. Thereby, the voltage imbalance between the first capacitor and the second capacitor can be reduced.

[0055] Also, in the charging device 10 according to the embodiment, the ECU 60 repeatedly switches the on and off states of the first switching element SB1 and the second switching element SB2 of the balancer circuit 26 to move the charge of the second capacitor C2 to the first capacitor C1, thereby eliminating the voltage imbalance between the first capacitor C1 and the second capacitor C2.

[0056] And in the charging device 10 according to the embodiment, when the voltage of the second capacitor C2 exceeds the threshold value during the charging of the battery 12 by the DC charger 30, the balancer circuit 26 is driven to move the charge of the second capacitor C2 to the first capacitor C1, thereby suppressing the voltage of the second capacitor C2 from reaching the capacitor upper limit voltage. Therefore, the charging device 10 according to the embodiment can continue charging the battery 12 without stopping the charging operation before the completion of charging the battery 12 due to overcharging of the second capacitor C2.

Explanation of Signs

[0057] 10 Charging device 12 Battery 16 Capacitor section 18 Inverter 20 Motor generator 22 Positive busbar 24 Negative busbar 26 Balancer circuit 28 Reactor 30 DC charger 32N N terminal 32P P terminal 40 Charging relay device 42N, 42P Charging relay 44P Reactor 50 Charger connection part 60 ECU 62 Charging control part 64 Gate signal generation part C1 First capacitor C2 Second capacitor DU1, DU2, DV1, DV2, DW1, DW2 Diode SB1, SU1, SV1, SW1 First switching element SB2, SU2, SV2, SW2 Second switching element SU3, SV3, SW3 Third switching element SU4, SV4, SW4 Fourth switching element

Claims

【Claim 1】 A capacitor section in which a first capacitor and a second capacitor are connected in series between a positive electrode terminal and a negative electrode terminal of a storage battery; A first switching element, a second switching element, a third switching element, and a fourth switching element connected in series, a cathode side connected to a wiring connecting the first switching element and the second switching element, and an anode side connected to a wiring connecting the first capacitor and the second capacitor. A first diode, an anode side connected to a wiring connecting the third switching element and the fourth switching element, and a cathode side connected to a wiring connecting the first capacitor and the second capacitor. A second diode, and by turning on and off the first switching element, the second switching element, the third switching element, and the fourth switching element respectively, a three-level inverter capable of selectively outputting a voltage of any one of three different voltage values to a motor generator. A power converter connected in parallel with the storage battery for three phases of U phase, V phase, and W phase; A control device for controlling switching between on and off of each switching element of the power converter; A first connection terminal electrically connected to a P terminal of a DC charger between the first switching element and the second switching element in the three-level inverter of any one of the U phase, the V phase, and the W phase; A second connection terminal electrically connected to an N terminal of the DC charger between the third switching element and the fourth switching element in the three-level inverter of another one of the U phase, the V phase, and the W phase; A charging device comprising: A balancer circuit that is connected in parallel with the storage battery and the capacitor section between the storage battery and the capacitor section, and that moves charges from the first capacitor to the second capacitor when the voltage of the first capacitor exceeds a preset threshold value; The threshold value is a voltage lower than the capacitor upper limit voltage and higher than a voltage that is half of the fully charged voltage of the storage battery; The balancer circuit is composed of a first balancer switching element, a second balancer switching element, and a reactor; The first balancing switching element and the second balancing switching element are connected in series between the positive terminal and the negative terminal of the storage battery. One side of the reactor is connected between the first balancing switching element and the second balancing switching element, and the other side of the reactor is connected between the first capacitor and the second capacitor. The control device During charging of the storage battery by the DC charger, when the voltage of the first capacitor is higher than the voltage of the second capacitor and the voltage of the first capacitor exceeds the threshold value, the first balancing switching element is turned on, and the second balancing switching element is turned off. Then, at a predetermined timing when the voltage of the first capacitor falls below the threshold value, the first balancing switching element is turned off, and the second balancing switching element is turned on. A charging device characterized by performing on / off switching control of the first balancing switching element and the second balancing switching element.

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