Power conversion device and program

Abstract

Power conversion device comprising: an upper arm switch (SWH) and a lower arm switch (SWL) connected in series; a first capacitor (21) electrically connected in parallel to the upper arm switch and the lower arm switch; a coil (11) having a first end side electrically connected to a connection point of the upper arm switch and the lower arm switch; a second capacitor (90); and a low-potential-side electrical path (22L) electrically connected to the lower arm switch. One of the high-potential-side electrical path and the low-potential-side electrical path is electrically connected to the second end side of the coil via a second capacitor. The other of the high-potential-side electrical path and the low-potential-side electrical path is electrically connected to the second end side of the coil via an electricity storage unit (33). A power conversion device is provided with a control unit (100) that opens and closes an upper arm switch and a lower arm switch.

Description

Citation of related applications

[0001] This application is based on Japanese Patent Application No. 2022-144022 filed on September 9, 2022, and the contents thereof are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to a power conversion device and a program. Background Art

[0003] Conventionally, as a method for raising the temperature of a plurality of batteries, there is known a method of electrically connecting a battery compartment and a winding of a rotating electric machine, opening and closing an upper arm switch and a lower arm switch so that current flows between the batteries via an inverter and the winding. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2020-120566 Summary of the invention

[0005] However, high-frequency current may be generated in conjunction with the above-mentioned switching. As a method for suppressing the high-frequency current from flowing into the battery, a capacitor may be provided on the output side of the winding. A method for increasing the temperature when such a capacitor is provided is required.

[0006] The present invention has been made in view of the above-mentioned technical problems, and an object of the present invention is to provide a power conversion device and a program capable of raising the temperature of a power storage unit.

[0007] This disclosure includes: An upper arm switch and a lower arm switch connected in series; a first capacitor electrically connected in parallel with the upper arm switch and the lower arm switch; a coil, a first end side of which is electrically connected to a connection point between the upper arm switch and the lower arm switch; a second capacitor; a high potential side electrical path electrically connected to the upper arm switch; a low potential side electrical path electrically connected to the lower arm switch; One of the high potential side electrical path and the low potential side electrical path is electrically connected to the second end side of the coil via the second capacitor, The other of the high potential side electrical path and the low potential side electrical path is electrically connected to the second end side of the coil via the power storage unit, A control unit is included that opens and closes the upper arm switch and the lower arm switch.

[0008] According to the above configuration, by opening and closing the upper arm switch and the lower arm switch, a ripple current can flow between the power storage unit and the second capacitor via the coil. The internal resistance of the battery can consume power and the battery can be heated by self-heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above objects, other objects, features and advantages of the present disclosure will become more apparent with reference to the accompanying drawings and the following detailed description. Figure 1 It is a diagram showing the overall configuration of the system according to the first embodiment. Figure 2 This is a flowchart for explaining an operation example of the control device according to the first embodiment. Figure 3 This is a flowchart for explaining an operation example of the control device according to the first embodiment. Figure 4 This is a diagram for explaining one mode of the circuit configuration of the first embodiment. Figure 5 This is a diagram for explaining one form of an equivalent circuit of the first embodiment. Figure 6 This is a diagram for explaining one form of an equivalent circuit of the first embodiment. Figure 7 This is a diagram for explaining one form of an equivalent circuit of the first embodiment. Figure 8 This is a diagram for explaining one form of an equivalent circuit of the first embodiment. Fig. 9 It is a diagram showing the simulation results of the first embodiment. Fig.10 This is a diagram for explaining one form of an equivalent circuit of the first embodiment. Fig.11 This is a diagram for explaining one mode of the circuit configuration of the first embodiment. Fig.12 This is a diagram for explaining one mode of the circuit configuration of the second embodiment. Fig.13 This is a diagram for explaining one mode of an equivalent circuit of the second embodiment. Fig.14 This is a diagram for explaining one mode of the circuit configuration of the third embodiment. Fig.15 This is a diagram for explaining one mode of the circuit configuration of the fourth embodiment. Fig.16 This is a diagram for explaining one mode of the circuit configuration of the fifth embodiment. Fig.17 This is a diagram for explaining one mode of the circuit configuration of the sixth embodiment. DETAILED DESCRIPTION

[0010] Hereinafter, multiple embodiments are described with reference to the accompanying drawings. In multiple embodiments, functionally and / or structurally corresponding parts and / or associated parts are sometimes marked with the same reference numerals or reference numerals that are different by more than one hundred. For the corresponding parts and / or associated parts, reference can be made to the description of other embodiments.

[0011] <First embodiment> A first embodiment of the power conversion device of the present disclosure will be described below with reference to the drawings. The power conversion device of this embodiment is installed in an electric vehicle such as an electric car or a hybrid car, an electric aircraft, an electric boat, etc., to constitute an electric mobile system.

[0012] The system includes a power conversion device. Figure 1 As shown, the power conversion device includes a motor 10, an inverter 20, a high potential side electrical path 22H and a low potential side electrical path 22L. The motor 10 is a three-phase synchronous machine, including a star-connected U, V, and W phase armature winding 11 and a rotor not shown. The armature winding 11 of each phase is configured to be staggered by 120° in electrical angle. The motor 10 is, for example, a permanent magnet synchronous machine. The rotor can transmit power to the driving wheels of the vehicle. Therefore, the motor 10 is a source of torque that drives the vehicle.

[0013] The inverter 20 includes a series connection of three corresponding upper arm switches SWH and lower arm switches SWL. The upper arm switch SWH is connected in reverse parallel to an upper arm diode DH as a freewheeling diode, and the lower arm switch SWL is connected in reverse parallel to a lower arm diode DL as a freewheeling diode. In the present embodiment, each switch SWH, SWL is an IGBT.

[0014] The inverter 20 includes a smoothing capacitor 21. The high potential side terminal of the smoothing capacitor 21 is connected to the first end side of the long high potential side electrical path 22H. The low potential side terminal of the smoothing capacitor 21 is connected to the first end side of the long low potential side electrical path 22L. In addition, the smoothing capacitor 21 can also be provided outside the inverter 20. The smoothing capacitor 21 is equivalent to the "first capacitor".

[0015] In each phase, the connection point between the emitter as the low potential side terminal of the upper arm switch SWH and the collector as the high potential side terminal of the lower arm switch SWL is connected to the first end of the armature winding 11 via a conductive member 23 such as a busbar. The second ends of the armature windings 11 of each phase are connected to each other at a neutral point. In addition, in the present embodiment, the number of turns of the armature windings 11 of each phase is set to be the same. As a result, the inductance of the armature windings 11 of each phase is set to be the same.

[0016] The collector of the upper arm switch SWH of each phase is connected to the high potential side electric path 22H, and the emitter of the lower arm switch SWL of each phase is connected to the low potential side electric path 22L.

[0017] The system includes a first battery 31 (equivalent to the "first power storage unit") and a second battery 32 (equivalent to the "second power storage unit"). Each battery 31, 32 serves as a power supply source for driving the rotor of the motor 10 to rotate. Each battery 31, 32 is a battery pack constituted as a series connection of single cells, i.e., battery cells. The positive terminal of the first battery 31 is connected to the high potential side electrical path 22H, and the negative terminal of the second battery 32 is connected to the low potential side electrical path 22L. In the present embodiment, the terminal voltage (e.g., rated voltage) of the first battery 31 is 400V, and the terminal voltage (e.g., rated voltage) of the second battery 32 is 100V. The battery cell is, for example, a secondary battery such as a lithium ion battery.

[0018] Each battery 31, 32 can be charged by an external charger to be described later provided outside the vehicle. The external charger is, for example, a stationary charger. A positive electrode side connection portion to which a positive terminal of an external charger can be connected is provided at a second end side of the high potential side electrical path 22H on the opposite side to the connection point side of the smoothing capacitor 21. A negative electrode side connection portion to which a negative terminal of an external charger can be connected is provided at a second end side of the low potential side electrical path 22L on the opposite side to the connection point side of the smoothing capacitor 21.

[0019] The power conversion device includes a main switch for electrically connecting or disconnecting the first and second storage batteries 31 and 32 and the inverter 20. In detail, as the main switch, a high potential side main switch SMRH and a low potential side main switch SMRL are provided. In addition, the power conversion device includes a charging switch for electrically connecting or disconnecting the external charger and the first and second storage batteries 31 and 32. In detail, as the charging switch, a high potential side charging switch DCRH and a low potential side charging switch DCRL are provided. In the present embodiment, each switch SMRH, SMRL, DCRH, DCRL is described as a mechanical relay, but is not limited to this, and can also be a semiconductor switch element. Each switch SMRH, SMRL, DCRH, DCRL blocks the flow of bidirectional current when it is turned off, and allows the flow of bidirectional current when it is turned on. In the high potential side electrical path 22H, the high potential side main switch SMRH and the high potential side charging switch DCRH are provided in sequence from the inverter 20 side. In the low potential side electrical path 22L, a low potential side main switch SMRL and a low potential side charging switch DCRL are provided in order from the inverter 20 side.

[0020] The power conversion device includes an inter-battery switch 40, an inter-negative electrode bypass switch 50, a motor side switch 60, and a connection switch 80, which are switches for switching the connection state of the first storage battery 31 and the second storage battery 32 to a state of series connection or a state of parallel connection with respect to an external charger. In the present embodiment, the inter-battery switch 40, the inter-negative electrode bypass switch 50, the motor side switch 60, and the connection switch 80 are described as mechanical relays, but are not limited to this, and may also be semiconductor switch elements. The inter-battery switch 40, the inter-negative electrode bypass switch 50, the motor side switch 60, and the connection switch 80 prevent the flow of bidirectional current when they are turned off, and allow the flow of bidirectional current when they are turned on. The inter-battery switch 40 is equivalent to a "switch between storage units". The motor side switch 60 is equivalent to a "coil side switch".

[0021] The inter-battery switch 40 is provided in the inter-battery electrical path 24 (corresponding to the "inter-storage unit electrical path") that connects the negative terminal of the first storage battery 31 and the positive terminal of the second storage battery 32. By turning on the inter-battery switch 40, the negative terminal of the first storage battery 31 and the positive terminal of the second storage battery 32 are electrically connected. On the other hand, by turning off the inter-battery switch 40, the negative terminal of the first storage battery 31 and the positive terminal of the second storage battery 32 are electrically disconnected.

[0022] The negative electrode bypass switch 50 connects the negative terminal of the first battery 31 and the low potential side electrical path 22L. By turning on the negative electrode bypass switch 50, the negative terminal of the first battery 31 and the negative terminal of the second battery 32 are electrically connected. On the other hand, by turning off the negative electrode bypass switch 50, the negative terminal of the first battery 31 and the negative terminal of the second battery 32 are electrically disconnected.

[0023] The motor side switch 60 and the connection switch 80 are provided in the motor side electrical path 25, and the motor side electrical path 25 connects the position of the inter-battery electrical path 24 closer to the second battery 32 side than the inter-battery switch 40 and the neutral point of the armature winding 11. More specifically, the connection switch 80 is provided in the motor side electrical path 25 at a position closer to the neutral point side than the motor side switch 60. By turning on the motor side switch 60 and the connection switch 80, the neutral point of the armature winding 11 and the positive terminal of the second battery 32 are electrically connected. On the other hand, by turning off the motor side switch 60 and the connection switch 80, the neutral point of the armature winding 11 and the positive terminal of the second battery 32 are electrically disconnected. The motor side electrical path 25 is a path that electrically connects the neutral point of the armature winding 11 and the portion of the inter-battery electrical path 24 closer to the second battery 32 side than the inter-battery switch 40. The motor side electrical path 25 corresponds to the "coil side electrical path".

[0024] The power conversion device includes a first voltage sensor 71 for detecting the voltage between the terminals of the first battery 31 and a second voltage sensor 72 for detecting the voltage between the terminals of the second battery 32. The power conversion device includes a first current sensor 73 for detecting the current flowing through the first battery 31 and a second current sensor 74 for detecting the current flowing through the second battery 32. The first current sensor 73 is provided on an electrical path connecting the positive terminal of the first battery 31 and the high potential side electrical path 22H. The second current sensor 74 is provided on an electrical path connecting the negative terminal of the second battery 32 and the low potential side electrical path 22L. The power conversion device includes a first temperature sensor 75 for detecting the temperature of the first battery 31 and a second temperature sensor 76 for detecting the temperature of the second battery 32. In addition, as other sensors, the power conversion device includes a rotation angle sensor for detecting the rotation angle (electrical angle) of the rotor and a phase current sensor for detecting the phase current flowing through the armature winding 11 of each phase.

[0025] The detection value of each sensor is input to the control device 100 (equivalent to the "control unit") included in the power conversion device. The control device 100 is mainly composed of a microcomputer 101, and the microcomputer 101 includes a CPU. The functions provided by the microcomputer 101 can be provided by software recorded in a physical memory device and a computer that executes the software, only software, only hardware, or a combination thereof. For example, in the case where the microcomputer 101 is provided by an electronic circuit as hardware, it can be provided by a digital circuit or an analog circuit including a plurality of logic circuits. For example, the microcomputer 101 executes a program stored in a non-transitory tangible storage medium (non-transitory tangible storage medium) included in itself as a storage unit. A method corresponding to the program is executed by executing the program. The storage unit is, for example, a non-volatile memory. In addition, the program stored in the storage unit can be updated, for example, via a communication network such as OTA (Over The Air) or the Internet.

[0026] The control device 100 opens and closes the switches SWH and SWL constituting the inverter 20 based on the detection values ​​of the sensors to feedback control the control amount of the motor 10 as a command value. The control amount is, for example, torque. In each phase, the upper arm switch SWH and the lower arm switch SWL are alternately turned on. Through this feedback control, the rotational power of the rotor is transmitted to the drive wheels, and the vehicle travels.

[0027] The positive electrode side connection part of the high potential side electrical path 22H and the negative electrode side connection part of the low potential side electrical path 22L are interfaces for connecting to an external charger. In this embodiment, the external charger is a low voltage charger or a high voltage charger. The charging voltage of the low voltage charger is a voltage lower than the terminal voltage (specifically, the rated voltage) of the series connection body of the first and second storage batteries 31 and 32, for example, 400V.

[0028] The charging voltage of the high-voltage charger is a voltage higher than the rated voltage of the series connection of the first and second storage batteries 31 and 32, for example, 800 V. For example, when a user or an operator connects an external charger to each connection portion and the first and second storage batteries 31 and 32 are charged by the external charger, the high-potential side charging switch DCRH and the low-potential side charging switch DCRL are switched to the on state by the control device 100.

[0029] On the other hand, when charging by an external charger is not performed or when an external charger is not connected, the high potential side charging switch DCRH and the low potential side charging switch DCRL are switched to an off state by the control device 100. When the positive electrode side connection part and the negative electrode side connection part are exposed to the outside from the housing of the power conversion device, they may touch the user or the operator. By turning the high potential side charging switch DCRH and the low potential side charging switch DCRL to an off state, electric shock is prevented.

[0030] The portion between the motor-side switch 60 and the connection switch 80 in the motor-side electrical path 25 is connected to the low-potential-side electrical path 22L via a neutral point capacitor 90. The reason for providing the neutral point capacitor 90 between the motor-side electrical path 25 and the low-potential-side electrical path 22L is as follows. In the charging process when the external charger is connected, a high-frequency current accompanying switching is generated. In order to suppress the high-frequency current accompanying switching from the inverter 20 side to flow into the first and second batteries 31, 32 and the external charger, the neutral point capacitor 90 is provided. The neutral point capacitor 90 is equivalent to the "second capacitor".

[0031] The low potential side main switch SMRL is connected in parallel with a series connection body of a precharge switch SP and a resistor 95. The precharge switch SP is used, for example, in a precharge process for charging the smoothing capacitor 21 or the neutral point capacitor 90 when the power conversion device is started. In addition, the series connection body of the precharge switch SP and the resistor 95 may be omitted.

[0032] Next, refer to Figure 2 Flow chart of Figure 1 In the circuit configuration described above, an example of a method of raising the temperature of the first storage battery 31 and the second storage battery 32 will be described. The temperature increase control is performed by the control device 100. This process is repeatedly executed at predetermined time intervals.

[0033] In step S101, the control device 100 determines whether there is a request for temperature increase of the first battery 31 and the second battery 32. For example, the control device 100 can determine that there is a request for temperature increase when the temperature TB1 of the first battery 31 detected by the first temperature sensor 75 and the temperature TB2 of the second battery 32 detected by the second temperature sensor 76 are lower than the target temperature. The control device 100 may determine that there is a request for temperature increase when either the temperature TB1 or the temperature TB2 is lower than the target temperature. In addition, the control device 100 may determine that there is a request for temperature increase when the average temperature of the temperature TB1 and the temperature TB2 is lower than the target temperature. The function of the control device 100 in step S101 corresponds to a "determination unit". When the processing of step S101 is Yes, that is, when the control device 100 determines that there is a request for temperature increase, the processing proceeds to step S102. On the other hand, when the processing of step S101 is No, that is, when the control device 100 determines that there is no request for temperature increase, the control device 100 ends the processing.

[0034] In step S102, the control device 100 performs an opening operation on each switch. Specifically, the control device 100 performs an opening operation on the high potential side main switch SMRH, the low potential side main switch SMRL, the pre-charge switch SP, the high potential side charging switch DCRH, the low potential side charging switch DCRL, the inter-battery switch 40, the inter-negative electrode bypass switch 50, the motor side switch 60, and the connection switch 80.

[0035] In step S103, the control device 100 adjusts the amplitude of the current flowing through the first storage battery 31 and the second storage battery 32. The amplitude is obtained based on the power and temperature required for temperature rise, for example. The control device 100 may also calculate the difference between the temperature TB1 of the first storage battery 31 or the temperature TB2 of the second storage battery 32 and the target temperature, and the larger the difference, the larger the amplitude. In the present embodiment, the current flowing through the first storage battery 31 and the second storage battery 32 is a ripple current containing a ripple component. The waveform of the ripple current is not particularly limited, and may be a sine wave or a rectangular wave.

[0036] In step S104, the control device 100 performs activation control of each switch. In the present embodiment, activation control is performed while determining whether each switch has a malfunction (for example, is fixedly turned on or is fixedly turned off). The details of activation control will be described later.

[0037] In step S105 , the control device 100 controls the upper arm switch SWH and the lower arm switch SWL of the inverter 20 to flow a ripple current into the first battery 31 and the second battery 32 to increase the temperature.

[0038] In step S106, the control device 100 determines whether the temperature TB1 of the first battery 31 and the temperature TB2 of the second battery 32 have reached the target temperature. When the processing of step S106 is YES, that is, when the control device 100 determines that the temperature TB1 of the first battery 31 and the temperature TB2 of the second battery 32 have reached the target temperature, the processing proceeds to step S107. On the other hand, when the processing of step S106 is NO, that is, when the control device 100 determines that the temperature TB1 of the first battery 31 and the temperature TB2 of the second battery 32 have not reached the target temperature, the processing returns to step S105.

[0039] In step S107, the control device 100 turns each switch in the on state to the off state, and ends the temperature increase control.

[0040] Next, refer to Figure 3 The details of the subroutine of the above-mentioned "startup control of each switch" are explained with reference to the flowchart.

[0041] In step S201, the control device 100 acquires the PN voltage detected by the sensor for detecting the PN voltage. The PN voltage refers to the voltage between the high potential side electrical path 22H and the low potential side electrical path 22L. The process proceeds to step S202, and the control device 100 determines whether the PN voltage is 0V. When the control device 100 determines that the PN voltage is 0V, that is, when the process of step S202 is yes, the process proceeds to step S205.

[0042] When the control device 100 determines that the PN voltage is not 0 V, that is, when the processing of step S202 is NO, the process proceeds to step S203. In step S203, the control device 100 determines whether the PN voltage is the total value of the voltage of the first battery 31 and the voltage of the second battery 32, that is, 500 V. When the control device 100 determines that the PN voltage is 500 V, that is, when the processing of step S203 is YES, the process proceeds to step S206.

[0043] In step S206, the control device 100 determines that the inter-battery switch 40 is fixedly connected. "Fixedly connected" is one of the failure modes of the switch, and is a failure mode in which the contacts of the switch are fixed in a connected state (on state). For example, in the case where the switch is a mechanical relay with contacts, when an arc is generated with the opening and closing of the contacts, or when a current exceeding the rated value flows through the contacts, the contacts may be welded. In this case, the switch is not controlled by the control device 100 and is fixed in the on state.

[0044] On the other hand, when the control device 100 determines that the PN voltage is not 500V, that is, when the processing of step S203 is No, the process proceeds to step S204. In step S204, the control device 100 determines whether the PN voltage is the voltage (400V) of the first storage battery 31. When the control device 100 determines that the PN voltage is 400V, that is, when the processing of step S204 is Yes, the process proceeds to step S207. In step S207, the control device 100 determines that the negative electrode bypass switch 50 is closed and fixed.

[0045] In step S205, the control device 100 turns on the negative electrode bypass switch 50. Next, in step S208, the control device 100 turns on the precharge switch SP. Next, in step S209, the control device 100 determines whether the PN voltage is 0 V. When the control device 100 determines that the PN voltage is 0 V, that is, when the processing of step S209 is yes, the processing proceeds to step S210.

[0046] On the other hand, when the control device 100 determines that the PN voltage is not 0 V, that is, when the processing of step S209 is NO, the processing proceeds to step S211. In step S211, the control device 100 determines that the high potential side main switch SMRH is fixedly turned on.

[0047] In step S210, the control device 100 acquires the voltage Vcb of the neutral point capacitor 90 detected by the NC voltage sensor, and determines whether the voltage Vcb of the neutral point capacitor 90 is 0 V. When the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is 0 V, that is, when the processing of step S210 is yes, the processing proceeds to step S212.

[0048] On the other hand, when the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is not 0 V, that is, when the processing of step S210 is NO, the processing proceeds to step S213. In step S213, the control device 100 determines that the motor side switch 60 is fixedly turned on.

[0049] In step S212, the control device 100 turns on the high potential side main switch SMRH. Then, in step S214, the smoothing capacitor 21 is charged. Then, in step S215, the control device 100 determines whether the PN voltage is 400 V. When the control device 100 determines that the PN voltage is 400 V, that is, when the processing of step S215 is yes, the processing proceeds to step S216.

[0050] On the other hand, when the control device 100 determines that the PN voltage is not 400V, that is, when the processing of step S215 is negative, the processing proceeds to step S217. In step S217, the control device 100 determines that the high potential side main switch SMRH is disconnected and fixed. "Disconnected and fixed" refers to a fault mode in which the contact of the switch is fixed in a non-connected state.

[0051] In step S216, the control device 100 turns off the precharge switch SP. Then, in step S218, the control device 100 turns on the motor side switch 60. Then, in step S219, the smoothing capacitor 21 is discharged. Then, in step S220, the control device 100 obtains the voltage Vinv of the smoothing capacitor 21 detected by the SC voltage sensor, and determines whether the voltage Vinv of the smoothing capacitor 21 is the voltage difference between the voltage of the first battery 31 and the voltage of the second battery 32, that is, 300V. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is 300V, that is, when the processing of step S220 is yes, the processing proceeds to step S221.

[0052] In step S221, the control device 100 turns on the connection switch 80. After steps S206, S207, S211, S213, and S217, the process proceeds to step S222, and the control device 100 stops the temperature increase control. In addition, when the processing of step S204 is No, the process also proceeds to step S222. This is because when the processing of step S204 is No, unexpected phenomena may occur.

[0053] Figure 4 Show Figure 3 The on / off state of each switch at the end of the processing of step S221. Figure 4 In the embodiment, the high potential side main switch SMRH, the negative electrode bypass switch 50, the motor side switch 60 and the connection switch 80 are in the on state, and the low potential side main switch SMRL, the pre-charging switch SP, the battery switch 40, the high potential side charging switch DCRH and the low potential side charging switch DCRL are in the off state. Figure 4 Temperature rise control is performed in the on and off states of the switches shown.

[0054] Figure 5 yes Figure 4An equivalent circuit of the circuit shown. In the equivalent circuit, a half-bridge circuit is formed by the upper arm switch SWH, the lower arm switch SWL and the smoothing capacitor 21. The first end side of the armature winding 11 is electrically connected to the connection point of the upper arm switch SWH and the lower arm switch SWL. The high potential side electrical path is electrically connected to the second end side of the armature winding 11 via the first battery 31 and the second battery 32. The low potential side electrical path is electrically connected to the second end side of the armature winding 11 via the neutral point capacitor 90. The positive terminal side of the first battery 31 is connected to the high potential side electrical path, and the negative terminal side of the first battery 31 is connected to the negative terminal side of the second battery 32.

[0055] Figure 6 Simplified Figure 5 Specifically, in Figure 6 In FIG. 1 , the first storage battery 31 and the second storage battery 32 are embodied as one storage battery, namely, the third storage battery 33. The voltage of the third storage battery 33 is the voltage difference between the voltage of the first storage battery 31 and the voltage of the second storage battery 32, namely, 300V.

[0056] Reference Figure 6 The specific temperature increase control method in this embodiment is described by using the equivalent circuit of Figure 6 The upper arm switch SWH and the lower arm switch SWL shown are turned on and the time of the on state is changed.

[0057] First, the flow of current when the upper arm switch SWH is turned on and the lower arm switch SWL is turned off will be described. Figure 7 As shown by the dotted arrow in FIG. , current flows in a closed circuit including the third battery 33, the upper arm switch SWH, and the armature winding 11. Figure 7 As shown by the dashed-dotted arrow, current flows in a closed circuit including the neutral point capacitor 90 , the armature winding 11 , and the smoothing capacitor 21 .

[0058] Next, the flow of current when the upper arm switch SWH is turned off and the lower arm switch SWL is turned on will be described. Figure 8 As shown by the dotted arrow in FIG. , current flows in a closed circuit including the third storage battery 33 and the smoothing capacitor 21. Figure 8 As indicated by the dashed-dotted arrow, current flows in a closed circuit including the neutral point capacitor 90, the armature winding 11, and the lower arm switch SWL.

[0059] Fig. 9 The simulation results are shown when the upper arm switch SWH and the lower arm switch SWL are alternately turned on. Fig. 9 (a) shows the transition of the current IB flowing through the third battery 33 . Fig. 9(b) shows the transition of the current IMG flowing through the armature winding 11 . Fig. 9 The solid line in (c) shows the change of the voltage Vinv of the smoothing capacitor 21. Fig. 9 The dotted line in (c) shows the transition of the voltage Vcb of the neutral point capacitor 90 . Fig. 9 (d) shows the transition of the gate signal of the upper arm switch SWH. Fig. 9 As shown in (d), regarding the time variation of the on / off state of the upper arm switch SWH and the lower arm switch SWL, the smaller the voltage Vinv of the smoothing capacitor 21 and the voltage Vcb of the neutral point capacitor 90 are, the shorter the on state of the upper arm switch SWH is.

[0060] like Fig. 9 As shown in (a), (b), and (c), as the voltage Vinv of the smoothing capacitor 21 and the voltage Vcb of the neutral point capacitor 90 increase, the current IB and the current IMG flow in the direction of battery discharge, that is, in the positive direction. As the voltage Vinv of the smoothing capacitor 21 and the voltage Vcb of the neutral point capacitor 90 decrease, the current IB and the current IMG flow in the direction of battery charging, that is, in the negative direction. In this way, by alternately turning on the upper arm switch SWH and the lower arm switch SWL and changing the time of the on state, the neutral point capacitor 90 can be charged using the energy stored in the armature winding 11, or the third battery 33 can be charged using the charge stored in the neutral point capacitor 90. That is, as Fig.10 As shown, by alternately turning on the upper arm switch SWH and the lower arm switch SWL and changing the time of the on state, a ripple current can flow between the third battery 33 and the neutral point capacitor 90 via the armature winding 11 .

[0061] According to the first embodiment described in detail above, the following effects can be obtained.

[0062] The power conversion device includes: a half-bridge circuit, which is composed of an upper arm switch SWH and a lower arm switch SWL connected in series and a smoothing capacitor 21 electrically connected in parallel with the upper arm switch SWH and the lower arm switch SWL; and an armature winding 11, whose first end side is electrically connected to the connection point of the upper arm switch SWH and the lower arm switch SWL. A high potential side electrical path 22H is electrically connected to the second end side of the armature winding 11 via a third battery 33, and a low potential side electrical path 22L is electrically connected to the second end side of the armature winding 11 via a neutral point capacitor 90.

[0063] In the above configuration, the control device 100 alternately turns on the upper arm switch SWH and the lower arm switch SWL and changes the time of the on state, thereby allowing the ripple current to flow between the third battery 33 and the neutral point capacitor 90 via the armature winding 11. In addition, the third battery 33 can be heated by self-heating while consuming power through the internal resistance of the third battery 33.

[0064] The third storage battery 33 is composed of the first storage battery 31 and the second storage battery 32 connected in series. Figure 5 As shown, the negative terminal side of the first battery 31 is connected to the negative terminal side of the second battery 32. In this way, by connecting the negative poles of the two batteries in series, the voltage of the entire circuit can be reduced. As a result, the ripple current flowing through the first battery 31 and the second battery 32 can be maintained, while reducing the ripple component of the current related to the opening and closing cycle of the half-bridge circuit. In addition, it is not limited to the connection between the negative terminal side of the first battery 31 and the negative terminal side of the second battery 32. As long as the positive terminal side of one of the first battery 31 and the second battery 32 is electrically connected to the high potential side electrical path 22H, the negative terminal side of the other side is electrically connected to the high potential side electrical path 22H.

[0065] exist Figure 5 In the equivalent circuit shown, since the same amount of ripple current flows through the first battery 31 and the second battery 32, when the internal resistance of the first battery 31 and the second battery 32 is the same, the heat generated by the first battery 31 and the second battery 32 is the same. This is useful when there is a voltage difference between the two batteries as in the present embodiment. The reason is explained. When there is a voltage difference between the two batteries, it is considered to make the current flow through the two batteries separately as in the above-mentioned prior art. It is known that the heat generated is the inverse proportional to the square of the voltage, so when there is a voltage difference between the two batteries, the heat generated deviates greatly. In this regard, according to the present embodiment, since the same amount of ripple current flows through the first battery 31 and the second battery 32, even if there is a voltage difference between the first battery 31 and the second battery 32, the heat generated is the same, and the generation of temperature difference is suppressed.

[0066] Not only the equivalent circuit, Figure 4 The circuit structure shown also suppresses the occurrence of temperature differences between the two batteries. Figure 4In the structure shown, the control device 100 performs opening and closing after turning off the inter-battery switch 40 and the low-potential side main switch SMRL and turning on the high-potential side main switch SMRH, the negative-electrode bypass switch 50, the motor-side switch 60, and the connection switch 80. As a result, ripple currents of the same magnitude flow in a closed circuit including the motor-side electrical path 25, the second battery 32, the low-potential side electrical path 22L, the negative-electrode bypass switch 50, the first battery 31, the high-potential side electrical path 22H, the upper arm switch SWH, and the motor 10. As a result, even if there is a voltage difference between the first battery 31 and the second battery 32, the heat generation is the same, and the generation of the temperature difference is suppressed.

[0067] In this embodiment, the armature winding 11 of the motor 10 mounted on the vehicle is used as the coil of the equivalent circuit. By making full use of such existing equipment, there is no need to add new equipment, which contributes to the weight reduction and cost reduction of the vehicle.

[0068] As in Figure 3 As described in step S220 of the control device 100, when it is determined that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage difference between the voltage of the first battery 31 and the voltage of the second battery 32, the control device 100 turns on the connection switch 80. When the connection switch 80 is turned on, an inrush current may flow due to the voltage difference between the voltages of the first battery 31 and the second battery 32 and the voltage of the smoothing capacitor 21. According to the present embodiment, when it is determined that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage difference between the voltage of the first battery 31 and the voltage of the second battery 32, the connection switch 80 is turned on, thereby suppressing the generation of the inrush current.

[0069] <Modification of the first embodiment> In the above description, the temperature increase control is performed when both the first storage battery 31 and the second storage battery 32 require temperature increase. However, there are also cases where only one of the storage batteries has a low temperature and only one of the storage batteries requires temperature increase. For example, consider the case where only the first storage battery 31 requires temperature increase. In this case, Fig.11 As shown, the control device 100 may also be configured to control the on / off state of each switch so that the current flows only through the first storage battery 31. Fig.11 In the figure, the high potential side main switch SMRH, the battery switch 40, the motor side switch 60 and the connecting switch 80 are in the on state, and the low potential side main switch SMRL, the pre-charging switch SP, the negative pole bypass switch 50, the high potential side charging switch DCRH and the low potential side charging switch DCRL are in the off state.

[0070] in the case of Fig.11In the on / off state shown, current flows in a closed circuit including the first battery 31, the high potential side electrical path 22H, the upper arm switch SWH, the motor 10, the neutral point, the connection switch 80, the motor side switch 60 and the inter-battery switch 40, so that only the first battery 31 can be heated.

[0071] <Second embodiment> Hereinafter, referring to the accompanying drawings, the second embodiment will be described with a focus on the differences from the first embodiment. Fig.12 As shown, the power conversion device includes a positive electrode bypass switch 51 connecting the positive terminal of the second storage battery 32 and the high potential side electrical path 22H, but does not include the previous Figure 1 The negative electrode bypass switch 50 is shown. In addition, the power conversion device includes a neutral point capacitor 91 between the motor side electrical path 25 and the high potential side electrical path 22H, but does not include the previous Figure 1 The neutral point capacitor 90 is shown. The motor side electric path 25 connects the neutral point of the armature winding 11 to a portion of the inter-battery electric path 24 closer to the first battery 31 than the inter-battery switch 40. The motor side electric path 25 is provided with a motor side switch 61.

[0072] The control device 100 performs a turning-on operation on the low-potential side main switch SMRL, the positive electrode bypass switch 51, the motor side switch 61, and the connection switch 80, and performs a turning-off operation on the high-potential side main switch SMRH, the pre-charging switch SP, the battery switch 40, the high-potential side charging switch DCRH, and the low-potential side charging switch DCRL. In this on-off state, the control device 100 alternately turns on the upper arm switch SWH and the lower arm switch SWL, and changes the time of the on state. As a result, the ripple current flows in a closed circuit including the first battery 31, the high-potential side electrical path 22H, the positive electrode bypass switch 51, the second battery 32, the low-potential side electrical path 22L, the lower arm switch SWL, the motor 10, the connection switch 80, and the motor side switch 61. Since the same ripple current flows through the first battery 31 and the second battery 32 , the first battery 31 and the second battery 32 are heated up, and even if there is a voltage difference between the first battery 31 and the second battery 32 , the heat generated is the same, and the temperature difference is suppressed.

[0073] In addition, Fig.12 The equivalent circuit when each switch is turned on and off as described above in the circuit shown is as follows Fig.13 As shown. Fig.13 In, with Figure 6 Compared with the equivalent circuit shown in FIG. 1 , the positions of the third storage battery 33 and the neutral point capacitor 90 are exchanged. Fig.13In the embodiment, the high potential side electrical path is electrically connected to the second end side of the armature winding 11 via the neutral point capacitor 90, and the low potential side electrical path is electrically connected to the second end side of the armature winding 11 via the third battery 33. Fig.13 In the equivalent circuit of Figure 6 The equivalent circuit of φ 1 similarly causes the ripple current to flow between the third battery 33 and the neutral point capacitor 90 via the armature winding 11 .

[0074] <Modification of Second Embodiment> The control device 100 may open the positive electrode bypass switch 51, the high potential side electrical path 22H, the precharge switch SP, the high potential side charging switch DCRH, and the low potential side charging switch DCRL, and close the low potential side electrical path 22L, the inter-battery switch 40, the motor side switch 61, and the connection switch 80. Thus, the ripple current flows in a closed circuit including the inter-battery switch 40, the second battery 32, the low potential side electrical path 22L, the lower arm switch SWL, the motor 10, the neutral point, the connection switch 80, and the motor side switch 61. Thus, for example, when only the second battery 32 requires a temperature increase, only the second battery 32 can be heated.

[0075] <Third Embodiment> Hereinafter, referring to the accompanying drawings, the third embodiment will be described with a focus on the differences from the first embodiment. Fig.14 As shown, the power conversion device further includes a positive electrode bypass switch 51 that connects the positive electrode terminal of the second storage battery 32 and the high potential side electrical path 22H.

[0076] The control device 100, for example, is capable of charging the second battery 32 alone through a low-voltage charger while the positive electrode bypass switch 51 is turned on and the negative electrode bypass switch 50, the battery switch 40, the motor side switch 60, the connecting switch 80, the high potential side main switch SMRH and the low potential side main switch SMRL are turned off.

[0077] <Fourth embodiment> Hereinafter, referring to the accompanying drawings, a fourth embodiment will be described with a focus on the differences from the above-mentioned embodiments. Fig.15 As shown, the motor-side switch includes a switch connecting the neutral point of the armature winding 11 and the positive terminal of the second battery 32 in addition to a switch connecting the neutral point of the armature winding 11 and the negative terminal of the first battery 31 .

[0078] The neutral point of the armature winding 11 is connected to the first end of the common path 26. The second end of the common path 26 is connected to the first end of the first electrical path 27, and the second end of the first electrical path 27 is connected to a position in the inter-battery electrical path 24 that is closer to the second battery 32 than the inter-battery switch 40. In addition, the second end of the common path 26 is connected to the first end of the second electrical path 28, and the second end of the second electrical path 28 is connected to a position in the inter-battery electrical path 24 that is closer to the first battery 31 than the inter-battery switch 40. A first motor side switch 60 is provided in the first electrical path 27. A second motor side switch 61 is provided in the second electrical path 28. In addition, the common path 26 may not be provided, and the first ends of the first electrical path 27 and the second electrical path 28 may be connected to the neutral point of the armature winding 11.

[0079] According to the present embodiment described above, it is possible to Figure 1 The circuit structure shown in Figure 2 Processing and Figure 3 processing.

[0080] <Fifth embodiment> Hereinafter, referring to the accompanying drawings, the fifth embodiment will be described with a focus on the differences from the second embodiment. Fig.16 As shown, the power conversion device further includes a negative electrode bypass switch 50 that connects the negative electrode terminal of the first storage battery 31 and the low potential side electrical path 22L.

[0081] The control device 100, for example, is capable of charging the first battery 31 alone through a low-voltage charger while the negative electrode bypass switch 50 is turned on and the positive electrode bypass switch 51, the battery switch 40, the motor side switch 60, the connecting switch 80, the high potential side main switch SMRH and the low potential side main switch SMRL are turned off.

[0082] <Sixth embodiment> Hereinafter, referring to the accompanying drawings, the sixth embodiment will be described with a focus on the differences from the above-mentioned embodiments. Fig.17 As shown, the motor-side switch includes a switch connecting the neutral point of the armature winding 11 and the positive terminal of the second battery 32 in addition to a switch connecting the neutral point of the armature winding 11 and the negative terminal of the first battery 31 .

[0083] The neutral point of the armature winding 11 is connected to the first end of the common path 26. The second end of the common path 26 is connected to the first end of the first electrical path 27, and the second end of the first electrical path 27 is connected to a position in the inter-battery electrical path 24 that is closer to the second battery 32 than the inter-battery switch 40. In addition, the second end of the common path 26 is connected to the first end of the second electrical path 28, and the second end of the second electrical path 28 is connected to a position in the inter-battery electrical path 24 that is closer to the first battery 31 than the inter-battery switch 40. A first motor side switch 60 is provided in the first electrical path 27. A second motor side switch 61 is provided in the second electrical path 28. In addition, the common path 26 may not be provided, and the first ends of the first electrical path 27 and the second electrical path 28 may be connected to the neutral point of the armature winding 11.

[0084] According to the present embodiment described above, it is possible to Figure 1 The circuit structure shown in Figure 2 Processing and Figure 3 processing.

[0085] <Other embodiments> The motor is not limited to star connection, but may be delta connection. In addition, the motor and inverter are not limited to three-phase, but may be two-phase or four-phase or more. In addition, the motor is not limited to a permanent magnet type synchronous machine having a permanent magnet as an excitation pole on the rotor, but may be a winding excitation type synchronous machine having an excitation winding as an excitation pole on the rotor. In this case, the rotor may have both an excitation winding and a permanent magnet. In addition, the motor is not limited to a synchronous machine, but may be an induction machine.

[0086] The switch of the inverter 20 is not limited to an IGBT with a freewheeling diode connected in antiparallel, but may be, for example, an N-channel MOSFET including a body diode. In this case, the high potential side terminal of the N-channel MOSFET serves as a drain, and the low potential side terminal serves as a source.

[0087] ·The control unit and method described in the present disclosure may also be implemented by a special-purpose computer, which is provided by constituting a processor and a memory, and the above-mentioned processor is programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and method described in the present disclosure may be implemented by a special-purpose computer, which is provided by constituting a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the control unit and method described in the present disclosure may be implemented by one or more special-purpose computers, which are constituted by a combination of a processor and a memory programmed to execute one or more functions and a processor constituted by one or more hardware logic circuits. In addition, the computer program may also be stored in a computer-readable non-temporary tangible recording medium as an instruction executed by a computer.

[0088] Hereinafter, characteristic structures extracted from the above-mentioned embodiments will be described. [Structure 1] A power conversion device comprises: an upper arm switch (SWH) and a lower arm switch (SWL) connected in series; a first capacitor (21) electrically connected in parallel with the upper arm switch and the lower arm switch; A coil (11), a first end side of which is electrically connected to a connection point between the upper arm switch and the lower arm switch; a second capacitor (90); a high potential side electrical path (22H) electrically connected to the upper arm switch; and a low potential side electrical path (22L) electrically connected to the lower arm switch, One of the high potential side electrical path and the low potential side electrical path is electrically connected to the second end side of the coil via the second capacitor, The other of the high potential side electrical path and the low potential side electrical path is electrically connected to the second end side of the coil via a power storage unit (33). A control unit (100) is included, which opens and closes the upper arm switch and the lower arm switch. [Structure 2] In the power conversion device according to configuration 1, the power storage unit is composed of a first power storage unit (31) and a second power storage unit (32) connected in series. The negative terminal side of the first power storage unit is connected to the negative terminal side of the second power storage unit. [Structure 3] The power conversion device according to configuration 2 further includes: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) electrically connecting the negative terminal of the first storage unit and the positive terminal of the second storage unit; a negative electrode bypass switch (50) for electrically connecting the negative electrode terminals of the first power storage unit and the second power storage unit; a coil side switch (60) provided in a coil side electrical path (25) electrically connecting the coil and the electrical path between the power storage unit; a connection switch (80) disposed in the coil-side electrical path at a position closer to the connection point than the coil-side switch; a high potential side switch (SMRH) provided between a connection point with the upper arm switch and a connection point with the positive terminal of the first power storage unit in the high potential side electrical path; and a low potential side switch (SMRL) provided between a connection point with the lower arm switch and a connection point with the negative terminal of the second power storage unit in the low potential side electrical path, The coil-side electrical path is a path that electrically connects the coil to a portion of the inter-storage unit electrical path that is closer to the second storage unit than the inter-storage unit switch. The control unit performs the opening and closing after turning off the inter-storage unit switch and the low potential side switch and turning on the high potential side switch, the inter-negative electrode bypass switch, the coil side switch, and the connection switch. [Structure 4] In the power conversion device described in Structure 3, the control unit performs the opening and closing after the negative electrode bypass switch and the low potential side switch are turned off, and the high potential side switch, the switch between the storage units, the coil side switch and the connection switch are turned on. [Structure 5] The power conversion device according to configuration 2 further includes: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) electrically connecting the negative terminal of the first storage unit and the positive terminal of the second storage unit; a positive electrode bypass switch (51) for electrically connecting the positive electrode terminals of the first power storage unit and the second power storage unit; a coil side switch (61) provided in a coil side electrical path (24) electrically connecting the coil and the electrical path between the power storage unit; a connection switch (80) disposed in the coil-side electrical path at a position closer to the connection point than the coil-side switch; a high potential side switch (SMRH) provided between a connection point with the upper arm switch and a connection point with the positive terminal of the first power storage unit in the high potential side electrical path; and a low potential side switch (SMRL) provided between a connection point with the lower arm switch and a connection point with the negative terminal of the second power storage unit in the low potential side electrical path, The coil-side electrical path is a path that electrically connects the coil to a portion of the inter-power storage unit electrical path that is closer to the first power storage unit than the inter-power storage unit switch. The control unit performs the opening and closing after turning off the inter-storage unit switch and the high potential side switch and turning on the low potential side switch, the inter-positive electrode bypass switch, the coil side switch, and the connection switch. [Structure 6] In the power conversion device described in Structure 5, the control unit performs the opening and closing after turning off the positive electrode bypass switch and the high potential side switch, and turning on the low potential side switch, the switch between the storage units, the coil side switch and the connection switch. [Structure 7] The power conversion device according to any one of structures 3 to 6 further includes a determination unit that determines whether there is a request to increase the temperature of at least one of the first power storage unit and the second power storage unit. The control unit performs the opening and closing when the determination unit determines that there is the temperature increase request. [Structure 8] In the power conversion device according to any one of structures 1 to 7, an electric motor (10) electrically connected to the connection point is used as the coil. [Structure 9] In the power conversion device according to any one of Configurations 3 to 8, the control unit changes the amplitude of a current flowing through at least one of the first power storage unit and the second power storage unit based on a temperature of at least one of the first power storage unit and the second power storage unit. [Structure 10] In the power conversion device according to any one of Configurations 3 to 9, the control unit turns on the connection switch when determining that the voltage of the first capacitor is equal to the voltage difference between the voltage of the first power storage unit and the voltage of the second power storage unit. [Structure 11] A program for a power conversion device, the power conversion device comprising: an upper arm switch (SWH) and a lower arm switch (SWL) connected in series; a first capacitor (21) electrically connected in parallel with the upper arm switch and the lower arm switch; A coil (11), a first end side of which is electrically connected to a connection point between the upper arm switch and the lower arm switch; a second capacitor (90); a high potential side electrical path (22H) electrically connected to the upper arm switch; and a low potential side electrical path (22L) electrically connected to the lower arm switch, One of the high potential side electrical path and the low potential side electrical path is electrically connected to the second end side of the coil via the second capacitor, The other of the high potential side electrical path and the low potential side electrical path is electrically connected to the second end side of the coil via a power storage unit (33). comprising a computer (101), The program causes the computer to execute the following processing: The upper arm switch and the lower arm switch are opened and closed.

[0089] Although the present disclosure is described based on the embodiments, it should be understood that the present disclosure is not limited to the above-mentioned embodiments and structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and methods, and other combinations and methods containing only one element, above or below them, also belong to the scope and thought range of the present disclosure.

Claims

1. A power conversion device, comprising: An upper arm switch (SWH) and a lower arm switch (SWL) connected in series; a first capacitor (21) electrically connected in parallel with the upper arm switch and the lower arm switch; A coil (11), a first end side of which is electrically connected to a connection point between the upper arm switch and the lower arm switch; a second capacitor (90); a high potential side electrical path (22H) electrically connected to the upper arm switch; as well as a low potential side electrical path (22L) electrically connected to the lower arm switch, One of the high potential side electrical path and the low potential side electrical path is electrically connected to the second end side of the coil via the second capacitor, The other of the high potential side electrical path and the low potential side electrical path is electrically connected to the second end side of the coil via a power storage unit (33). A control unit (100) is included, which opens and closes the upper arm switch and the lower arm switch.

2. The power conversion device according to claim 1, characterized in that: The power storage unit includes a first power storage unit (31) and a second power storage unit (32) connected in series. One of the first power storage unit and the second power storage unit has a positive terminal side electrically connected to the high potential side electrical path, and the other has a negative terminal side electrically connected to the high potential side electrical path.

3. The power conversion device according to claim 2, characterized in that: Also includes: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) electrically connecting the negative terminal of the first storage unit and the positive terminal of the second storage unit; a negative electrode bypass switch (50) for electrically connecting the negative electrode terminals of the first power storage unit and the second power storage unit; a coil side switch (60) provided in a coil side electrical path (25) electrically connecting the coil and the electrical path between the power storage unit; a connection switch (80) disposed in the coil-side electrical path at a position closer to the connection point than the coil-side switch; a high potential side switch (SMRH) provided between a connection point with the upper arm switch and a connection point with the positive terminal of the first power storage unit in the high potential side electrical path; and a low potential side switch (SMRL) provided between a connection point with the lower arm switch and a connection point with the negative terminal of the second power storage unit in the low potential side electrical path, The coil-side electrical path is a path that electrically connects the coil to a portion of the inter-storage unit electrical path that is closer to the second storage unit than the inter-storage unit switch. The control unit performs the opening and closing after turning off the switch between the power storage units and the low potential side switch and turning on the high potential side switch, the negative electrode bypass switch, the coil side switch, and the connection switch.

4. The power conversion device according to claim 3, characterized in that: The control unit performs the opening and closing after turning off the negative electrode bypass switch and the low potential side switch and turning on the high potential side switch, the switch between the power storage units, the coil side switch, and the connection switch.

5. The power conversion device according to claim 2, characterized in that: Also includes: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) electrically connecting the negative terminal of the first storage unit and the positive terminal of the second storage unit; a positive electrode bypass switch (51) for electrically connecting the positive electrode terminals of the first power storage unit and the second power storage unit; a coil side switch (61) provided in a coil side electrical path (25) electrically connecting the coil and the electrical path between the power storage unit; a connection switch (80) disposed in the coil-side electrical path at a position closer to the connection point than the coil-side switch; a high potential side switch (SMRH) provided between a connection point with the upper arm switch and a connection point with the positive terminal of the first power storage unit in the high potential side electrical path; and a low potential side switch (SMRL) provided between a connection point with the lower arm switch and a connection point with the negative terminal of the second power storage unit in the low potential side electrical path, The coil-side electrical path is a path that electrically connects the coil to a portion of the inter-storage unit electrical path that is closer to the first storage unit than the inter-storage unit switch. The control unit performs the opening and closing after turning off the inter-storage unit switch and the high potential side switch and turning on the low potential side switch, the inter-positive electrode bypass switch, the coil side switch, and the connection switch.

6. The power conversion device according to claim 5, characterized in that: The control unit performs the opening and closing after turning off the positive electrode bypass switch and the high potential side switch and turning on the low potential side switch, the switch between the power storage units, the coil side switch, and the connection switch.

7. The power conversion device according to any one of claims 3 to 6, characterized in that: further comprising a determination unit configured to determine whether there is a request to increase the temperature of at least one of the first power storage unit and the second power storage unit, The control unit performs the opening and closing when the determination unit determines that there is the temperature increase request.

8. The power conversion device according to claim 1, characterized in that: A motor (10) electrically connected to the connection point is used as the coil.

9. The power conversion device according to any one of claims 3 to 6, characterized in that: The control unit changes an amplitude of a current flowing through at least one of the first power storage unit and the second power storage unit based on a temperature of at least one of the first power storage unit and the second power storage unit.

10. The power conversion device according to any one of claims 3 to 6, characterized in that: The control unit turns on the connection switch when it is determined that the voltage of the first capacitor is equal to the voltage difference between the voltage of the first power storage unit and the voltage of the second power storage unit.

11. A program for a power conversion device, the power conversion device comprising: An upper arm switch (SWH) and a lower arm switch (SWL) connected in series; a first capacitor (21) electrically connected in parallel with the upper arm switch and the lower arm switch; A coil (11), a first end side of which is electrically connected to a connection point between the upper arm switch and the lower arm switch; a second capacitor (90); a high potential side electrical path (22H) electrically connected to the upper arm switch; as well as a low potential side electrical path (22L) electrically connected to the lower arm switch, One of the high potential side electrical path and the low potential side electrical path is electrically connected to the second end side of the coil via the second capacitor, The other of the high potential side electrical path and the low potential side electrical path is electrically connected to the second end side of the coil via a power storage unit (33). comprising a computer (101), The program causes the computer to execute the following processing: The upper arm switch and the lower arm switch are opened and closed.

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