Power conversion device, program, and control method

Abstract

This electric power conversion device is equipped with: a higher arm switch (SWH) and a lower arm switch (SWL) which are connected in series; a first capacitor (21) which is electrically connected in parallel to the higher arm switch and the lower arm switch; a coil (11), a first end of which is electrically connected to the connecting point between the higher arm switch and the lower arm switch; a second capacitor (90); a higher potential-side electric path (22H) which is electrically connected to the higher arm switch; and a lower potential-side electric path (22L) which is electrically connected to the lower arm switch. A second end side of the coil is electrically connected via the second capacitor to one path among the higher potential-side electric path and the lower potential-side electric path. The second end side of the coil is electrically connected via a power storage unit (33) to the other path among the higher potential-side electric path and the lower potential-side electric path. The electric power conversion device is also equipped with a control unit (100) for switching between the higher arm switch and the lower arm switch.

Description

Power conversion device and program CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2022-144020, filed on September 9, 2022, the contents of which are incorporated herein by reference.

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

[0003] Conventionally, a known method for raising the temperature of multiple storage batteries is to electrically connect the storage batteries to the windings of a rotating electric machine and switch the upper arm switches and lower arm switches so that current flows between the storage batteries via the inverter and the windings.

[0004] Japanese Patent Application Laid-Open No. 2020-120566

[0005] However, high-frequency currents can be generated due to the switching. A possible solution to prevent high-frequency currents from flowing into the battery is to install a capacitor on the output side of the winding. A method for raising the temperature when such a capacitor is installed is needed.

[0006] The present disclosure has been made in consideration of the above-described problems, and aims to provide a power conversion device and a program that are capable of increasing the temperature of a power storage unit.

[0007] The present disclosure comprises: an upper arm switch and a lower arm switch connected in series; a first capacitor electrically connected in parallel to the upper arm switch and the lower arm switch; a coil having a first end 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 electrically connected to a second end of the coil via the second capacitor; and the other of the high potential side electrical path and the low potential side electrical path electrically connected to the second end of the coil via a power storage unit; and a control unit that switches the upper arm switch and the lower arm switch.

[0008] According to the above configuration, by switching the upper arm switch and the lower arm switch, a ripple current can be caused to flow between the power storage unit and the second capacitor via the coil. Power is consumed by the internal resistance of the storage battery, and the temperature of the storage battery can be increased by self-heating.

[0009] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is an overall configuration diagram of a system according to a first embodiment, Fig. 2 is a flowchart illustrating an example of operation of a control device according to the first embodiment, Fig. 3 is a flowchart illustrating an example of operation of a control device according to the first embodiment, Fig. 4 is a diagram illustrating an example of a circuit configuration according to the first embodiment, Fig. 5 is a diagram illustrating an example of an equivalent circuit according to the first embodiment, Fig. 6 is a diagram illustrating an example of an equivalent circuit according to the first embodiment, Fig. 7 is a diagram illustrating an example of an equivalent circuit according to the first embodiment, Fig. 8 is a diagram illustrating an example of an equivalent circuit according to the first embodiment, and Fig. 9 is a diagram illustrating an example of a circuit configuration according to the first embodiment. 10 is a diagram illustrating one aspect of the equivalent circuit according to the first embodiment, FIG. 11 is a diagram illustrating one aspect of the circuit configuration according to the first embodiment, FIG. 12 is a diagram illustrating one aspect of the circuit configuration according to the second embodiment, FIG. 13 is a diagram illustrating one aspect of the equivalent circuit according to the second embodiment, FIG. 14 is a diagram illustrating one aspect of the circuit configuration according to the third embodiment, FIG. 15 is a diagram illustrating one aspect of the circuit configuration according to the fourth embodiment, FIG. 16 is a diagram illustrating one aspect of the circuit configuration according to the fifth embodiment, and FIG. 17 is a diagram illustrating one aspect of the circuit configuration according to the sixth embodiment.

[0010] Several embodiments will be described with reference to the drawings. In several embodiments, functionally and / or structurally corresponding and / or associated parts may be designated by the same reference numerals or reference numerals that differ in the hundredth or more digit. For corresponding and / or associated parts, reference may be made to the descriptions of other embodiments.

[0011] A first embodiment of a power conversion device according to the present disclosure will now be described 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 ship, or the like, and forms an electric mobile body system.

[0012] The system includes a power conversion device. As shown in FIG. 1, 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 and includes star-connected armature windings 11 of U, V, and W phases, and a rotor (not shown). The armature windings 11 of each phase are arranged with an electrical angle offset of 120°. The motor 10 is, for example, a permanent magnet synchronous machine. The rotor is capable of transmitting power to the drive wheels of the vehicle. Therefore, the motor 10 serves as a source of torque for propelling the vehicle.

[0013] The inverter 20 includes three phases of series-connected upper-arm switches SWH and lower-arm switches SWL. An upper-arm diode DH, which is a freewheeling diode, is connected in antiparallel to the upper-arm switch SWH, and a lower-arm diode DL, which is also a freewheeling diode, is connected in antiparallel to the lower-arm switch SWL. In this embodiment, each of the switches SWH and SWL is an IGBT.

[0014] The inverter 20 includes a smoothing capacitor 21. A first end of a long high-potential side electrical path 22H is connected to a high-potential side terminal of the smoothing capacitor 21. A first end of a long low-potential side electrical path 22L is connected to a low-potential side terminal of the smoothing capacitor 21. The smoothing capacitor 21 may be provided outside the inverter 20. The smoothing capacitor 21 corresponds to the "first capacitor."

[0015] In each phase, a first end of the armature winding 11 is connected to a connection point between the emitter, which is the low potential terminal of the upper arm switch SWH, and the collector, which is the high potential terminal of the lower arm switch SWL, via a conductive member 23 such as a bus bar. Second ends of the armature windings 11 of each phase are connected to each other at a neutral point. In this embodiment, the armature windings 11 of each phase are set to have the same number of turns. As a result, the armature windings 11 of each phase are set to have the same inductance, for example.

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

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

[0018] Each of the storage batteries 31, 32 can be charged by an external charger (described later) that is provided outside the vehicle. The external charger is, for example, a stationary charger. A positive electrode connection part to which a positive terminal of the external charger can be connected is provided at a second end of the high-potential-side electrical path 22H opposite the connection point of the smoothing capacitor 21. A negative electrode connection part to which a negative terminal of the external charger can be connected is provided at a second end of the low-potential-side electrical path 22L opposite the connection point 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, 32 from the inverter 20. Specifically, the main switches include a high-side main switch SMRH and a low-side main switch SMRL. The power conversion device also includes a charging switch for electrically connecting or disconnecting the first and second storage batteries 31, 32 from an external charger. Specifically, the charging switches include a high-side charging switch DCRH and a low-side charging switch DCRL. In this embodiment, the switches SMRH, SMRL, DCRH, and DCRL are described as mechanical relays, but are not limited thereto and may be semiconductor switching elements. When turned off, the switches SMRH, SMRL, DCRH, and DCRL block bidirectional current flow, and when turned on, allow bidirectional current flow. The high-side main switch SMRH and the high-side charging switch DCRH are provided in this order from the inverter 20 side in the high-side electrical path 22H. The low potential side electrical path 22L is provided with a low potential side main switch SMRL and a low potential side charging switch DCRL in this order from the inverter 20 side.

[0020] The power conversion device includes an inter-battery switch 40, a negative-electrode bypass switch 50, a motor-side switch 60, and a connection switch 80 as switches for switching the connection state of the first storage battery 31 and the second storage battery 32 between a series connection state and a parallel connection state with an external charger. In this embodiment, the inter-battery switch 40, the 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 be semiconductor switching elements. The inter-battery switch 40, the negative-electrode bypass switch 50, the motor-side switch 60, and the connection switch 80 block bidirectional current flow when turned off and allow bidirectional current flow when turned on. The inter-battery switch 40 corresponds to the "inter-energy storage unit switch." The motor-side switch 60 corresponds to the "coil-side switch."

[0021] The inter-battery switch 40 is provided in an inter-battery electrical path 24 (corresponding to an "inter-power 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. When the inter-battery switch 40 is turned on, 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, when the inter-battery switch 40 is turned off, 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 electrode terminal of the first storage battery 31 and the low potential side electrical path 22L. When the negative electrode bypass switch 50 is turned on, the negative electrode terminal of the first storage battery 31 and the negative electrode terminal of the second storage battery 32 are electrically connected. When the negative electrode bypass switch 50 is turned off, the negative electrode terminal of the first storage battery 31 and the negative electrode terminal of the second storage battery 32 are electrically disconnected.

[0023] The motor-side switch 60 and the connection switch 80 are provided in a motor-side electrical path 25 that connects the portion of the inter-battery electrical path 24 closer to the second storage battery 32 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 closer to the neutral point than the motor-side switch 60. When the motor-side switch 60 and the connection switch 80 are turned on, the neutral point of the armature winding 11 is electrically connected to the positive terminal of the second storage battery 32. On the other hand, when the motor-side switch 60 and the connection switch 80 are turned off, the neutral point of the armature winding 11 is electrically disconnected from the positive terminal of the second storage battery 32. The motor-side electrical path 25 electrically connects the neutral point of the armature winding 11 and the portion of the inter-battery electrical path 24 closer to the second storage battery 32 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 that detects the terminal voltage of the first storage battery 31 and a second voltage sensor 72 that detects the terminal voltage of the second storage battery 32. The power conversion device also includes a first current sensor 73 that detects the current flowing through the first storage battery 31 and a second current sensor 74 that detects the current flowing through the second storage battery 32. The first current sensor 73 is provided on an electrical path connecting the positive terminal of the first storage 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 storage battery 32 and the low-potential side electrical path 22L. The power conversion device also includes a first temperature sensor 75 that detects the temperature of the first storage battery 31 and a second temperature sensor 76 that detects the temperature of the second storage battery 32. The power conversion device also includes other sensors, such as a rotation angle sensor that detects the rotation angle (electrical angle) of the rotor and phase current sensors that detect phase currents flowing through the armature windings 11 of each phase.

[0025] The detected values ​​of each sensor are input to a control device 100 (corresponding to a "controller") included in the power conversion device. The control device 100 is mainly configured with a microcomputer 101, which includes a CPU. The functions provided by the microcomputer 101 can be provided by software recorded in a physical memory device and a computer executing the software, software alone, hardware alone, or a combination thereof. For example, if the microcomputer 101 is provided by a hardware electronic circuit, the function can be provided by a digital circuit including multiple logic circuits or an analog circuit. For example, the microcomputer 101 executes a program stored in a non-transitory tangible storage medium serving as a memory unit included in the microcomputer 101. Execution of the program results in the execution of a method corresponding to the program. The memory unit is, for example, a non-volatile memory. The program stored in the memory unit can be updated via a communication network such as the Internet, for example, via OTA (Over the Air).

[0026] The control device 100 switches the switches SWH and SWL constituting the inverter 20 to feedback-control the control variable of the motor 10 to a command value based on the detection values ​​of the sensors. The control variable is, for example, torque. In each phase, the upper arm switch SWH and the lower arm switch SWL are alternately turned on. This feedback control transmits the rotational power of the rotor to the drive wheels, causing the vehicle to run.

[0027] The positive electrode connection portion of the high-potential side electrical path 22H and the negative electrode connection portion of the low-potential side electrical path 22L are interfaces for connection 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 lower than the inter-terminal voltage (specifically, the rated voltage) of the series-connected first and second storage batteries 31, 32, for example, 400 V.

[0028] The charging voltage of the high-voltage charger is higher than the rated voltage of the series-connected first and second storage batteries 31, 32, and is, for example, 800 V. For example, when a user or an operator connects an external charger to each connection portion and charges the first and second storage batteries 31, 32 using the external charger, the high-side charging switch DCRH and the low-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-side charging switch DCRH and the low-side charging switch DCRL are switched to the OFF state by the control device 100. If the positive-side connection portion and the negative-side connection portion are exposed to the outside from the housing of the power conversion device, they may be touched by a user or worker. By switching the high-side charging switch DCRH and the low-side charging switch DCRL to the OFF state, the occurrence of electric shock is prevented.

[0030] The low potential side electrical path 22L is connected to a portion of the motor side electrical path 25 between the motor side switch 60 and the connection switch 80 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: When an external charger is connected, a high frequency current is generated due to switching during charging. The neutral point capacitor 90 is provided to prevent the high frequency current generated due to switching from flowing from the inverter 20 side to the first and second storage batteries 31, 32 and the external charger. The neutral point capacitor 90 corresponds to the "second capacitor."

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

[0032] Next, an example of a method for raising the temperatures of the first storage battery 31 and the second storage battery 32 in the circuit configuration described in Fig. 1 will be described with reference to the flowchart in Fig. 2. The temperature raising 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 temperature increase request for the first storage battery 31 and the second storage battery 32. For example, the control device 100 can determine that there is a temperature increase request when the temperature TB1 of the first storage battery 31 detected by the first temperature sensor 75 and the temperature TB2 of the second storage battery 32 detected by the second temperature sensor 76 are below a target temperature. The control device 100 may determine that there is a temperature increase request when either the temperature TB1 or the temperature TB2 is below the target temperature. Alternatively, the control device 100 may determine that there is a temperature increase request when the average temperature of the temperature TB1 and the temperature TB2 is below the target temperature. The function of the control device 100 in step S101 corresponds to a "determination unit." If the process in step S101 is YES, i.e., if the control device 100 determines that there is a temperature increase request, the process proceeds to step S102. On the other hand, if the process of step S101 is NO, that is, if the control device 100 determines that there is no temperature increase request, the control device 100 ends the process.

[0034] In step S102, the control device 100 turns off each switch. Specifically, the control device 100 turns off 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 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 magnitude of the amplitude of the current flowing to the first storage battery 31 and the second storage battery 32. The magnitude of the amplitude is calculated, for example, based on the power required for temperature increase and the temperature. The control device 100 may 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 increase the amplitude as the difference increases. In this embodiment, the current flowing to the first storage battery 31 and the second storage battery 32 is a ripple current that includes 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 start-up control of each switch. In this embodiment, the start-up control is performed while determining whether or not a malfunction (for example, stuck on or stuck off) has occurred in each switch. Details of the start-up 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 pass a ripple current through the first storage battery 31 and the second storage battery 32 to raise their temperatures.

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

[0039] In step S107, the control device 100 turns off each switch that was turned on, thereby ending the temperature rise control.

[0040] Next, the details of the above-mentioned "switch start-up control" subroutine will be described with reference to the flowchart of FIG.

[0041] In step S201, the control device 100 acquires a PN voltage detected by a sensor that detects the PN voltage. The PN voltage is the voltage between the high-potential side electrical path 22H and the low-potential side electrical path 22L. The process proceeds to step S202, where the control device 100 determines whether the PN voltage is 0 V. If the control device 100 determines that the PN voltage is 0 V, that is, if the process in step S202 is YES, the process proceeds to step S205.

[0042] On the other hand, if the control device 100 determines that the PN voltage is not 0 V, that is, if the process in step S202 is NO, the process proceeds to step S203. In step S203, the control device 100 determines whether the PN voltage is 500 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32. If the control device 100 determines that the PN voltage is 500 V, that is, if the process in 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 stuck on. "Stuck on" is one of the switch failure modes, in which the switch contacts are stuck in a connected state (on state). For example, if the switch is a mechanical relay with contacts, the contacts may weld if an arc occurs when the contacts are opened or closed, or if a current exceeding the rated value flows through the contacts. In this case, the switch is stuck on regardless of the control of the control device 100.

[0044] On the other hand, if the control device 100 determines that the PN voltage is not 500 V, i.e., if the process in 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 (400 V) of the first storage battery 31. If the control device 100 determines that the PN voltage is 400 V, i.e., if the process in 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 stuck on.

[0045] In step S205, the control device 100 turns on the negative electrode bypass switch 50. In the following step S208, the control device 100 turns on the precharge switch SP. In the following step S209, the control device 100 determines whether the PN voltage is 0 V. If the control device 100 determines that the PN voltage is 0 V, that is, if the process of step S209 is YES, the process proceeds to step S210.

[0046] On the other hand, if the control device 100 determines that the PN voltage is not 0 V, that is, if the process of step S209 is NO, the process proceeds to step S211. In step S211, the control device 100 determines that the high potential side main switch SMRH is stuck 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. If the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is 0 V, that is, if the process of step S210 is YES, the process proceeds to step S212.

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

[0049] In step S212, the control device 100 turns on the high-side main switch SMRH. In the following step S214, the smoothing capacitor 21 is charged. In the following step S215, the control device 100 determines whether the PN voltage is 400 V. If the control device 100 determines that the PN voltage is 400 V, that is, if the process of step S215 is YES, the process proceeds to step S216.

[0050] On the other hand, if the control device 100 determines that the PN voltage is not 400 V, i.e., if the process of step S215 is NO, the process proceeds to step S217. In step S217, the control device 100 determines that the high potential side main switch SMRH is stuck off. "Stuck off" is a failure mode in which the switch contacts are fixed in a disconnected state.

[0051] In step S216, the control device 100 turns off the pre-charge switch SP. In the following step S218, the control device 100 turns on the motor-side switch 60. In the following step S219, the smoothing capacitor 21 is discharged. In the following step S220, the control device 100 acquires 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 300 V, which is the voltage difference between the voltage of the first storage battery 31 and the voltage of the second storage battery 32. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is 300 V, i.e., if the process of step S220 is YES, the process 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, where the control device 100 stops the temperature increase control. Note that if the process in step S204 is NO, the process also proceeds to step S222. This is because if the process in step S204 is NO, an unexpected phenomenon may have occurred.

[0053] Figure 4 shows the on / off states of each switch when the processing of step S221 in Figure 3 is completed. Specifically, in Figure 4, the high-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-side main switch SMRL, the pre-charge switch SP, the battery-to-battery switch 40, the high-side charging switch DCRH, and the low-side charging switch DCRL are in the off state. In this embodiment, temperature rise control is performed with the on / off states of each switch shown in Figure 4.

[0054] 5 is an equivalent circuit of the circuit shown in FIG. 4 . 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. A first end of the armature winding 11 is electrically connected to a connection point between the upper arm switch SWH and the lower arm switch SWL. A high-potential side electrical path is electrically connected to a second end of the armature winding 11 via a first storage battery 31 and a second storage battery 32. A low-potential side electrical path is electrically connected to the second end of the armature winding 11 via a neutral capacitor 90. A positive terminal of the first storage battery 31 is connected to the high-potential side electrical path, and a negative terminal of the first storage battery 31 is connected to the negative terminal of the second storage battery 32.

[0055] Fig. 6 is a simplified equivalent circuit of Fig. 5. Specifically, in Fig. 6, the first storage battery 31 and the second storage battery 32 are expressed as a single storage battery, the third storage battery 33. The voltage of the third storage battery 33 is 300 V, which is the voltage difference between the voltage of the first storage battery 31 and the voltage of the second storage battery 32.

[0056] A specific temperature rise control method in this embodiment will be described with reference to the equivalent circuit in Fig. 6. The control device 100 alternately turns on the upper arm switch SWH and the lower arm switch SWL shown in Fig. 6 to change the time for which they are in the on state.

[0057] First, a description will be given of the current flow when the upper arm switch SWH is turned on and the lower arm switch SWL is turned off. In this case, as shown by the dashed arrow in Fig. 7, a current flows through a closed circuit including the third storage battery 33, the upper arm switch SWH, and the armature winding 11. Also, as shown by the dashed arrow in Fig. 7, a current flows through a closed circuit including the neutral capacitor 90, the armature winding 11, and the smoothing capacitor 21.

[0058] Next, a description will be given of the current flow when the upper arm switch SWH is turned off and the lower arm switch SWL is turned on. As shown by the dashed arrow in Fig. 8, a current flows through a closed circuit including the third storage battery 33 and the smoothing capacitor 21. Also, as shown by the dashed arrow in Fig. 8, a current flows through a closed circuit including the neutral capacitor 90, the armature winding 11, and the lower arm switch SWL.

[0059] 9 shows simulation results 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 storage battery 33. FIG. 9(b) shows the transition of the current IMG flowing through the armature winding 11. The solid line in FIG. 9(c) shows the transition of the voltage Vinv of the smoothing capacitor 21, and the dashed line in FIG. 9(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. As shown in FIG. 9(d), the transition of the on-off states of the upper-arm switch SWH and the lower-arm switch SWL over time is such that the smaller the voltage Vinv of the smoothing capacitor 21 and the voltage Vcb of the neutral point capacitor 90, the shorter the on-state of the upper-arm switch SWH.

[0060] 9(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 currents IB and IMG flow in the positive direction, in which the battery is discharged, and as the voltage Vinv of the smoothing capacitor 21 and the voltage Vcb of the neutral point capacitor 90 decrease, the currents IB and IMG flow in the negative direction, in which the battery is charged. In this way, by alternately turning on the upper arm switch SWH and the lower arm switch SWL and changing the on-state time, it is possible to charge the neutral point capacitor 90 using the energy stored in the armature winding 11, or to charge the third storage battery 33 using the charge stored in the neutral point capacitor 90. That is, as shown in FIG. 10, by alternately turning on the upper arm switch SWH and the lower arm switch SWL and changing the time for which they are in the on state, a ripple current can be caused to flow between the third storage battery 33 and the neutral point capacitor 90 via the armature winding 11.

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

[0062] The power conversion device includes a half-bridge circuit including an upper arm switch SWH and a lower arm switch SWL connected in series, a smoothing capacitor 21 electrically connected in parallel to the upper arm switch SWH and the lower arm switch SWL, and an armature winding 11 having a first end electrically connected to a connection point between the upper arm switch SWH and the lower arm switch SWL. A high-potential side electrical path 22H and a second end of the armature winding 11 are electrically connected via a third storage battery 33, and a low-potential side electrical path 22L and a second end of the armature winding 11 are electrically connected 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 for which they are turned on, thereby allowing a ripple current to flow between the third storage battery 33 and the neutral point capacitor 90 via the armature winding 11. Then, power is consumed by the internal resistance of the third storage battery 33, and the third storage battery 33 can be heated up by self-heating.

[0064] The third storage battery 33 is composed of a first storage battery 31 and a second storage battery 32 connected in series. As shown in FIG. 5 , the negative terminal of the first storage battery 31 is connected to the negative terminal of the second storage battery 32. By connecting the negative electrodes of the two storage batteries in series in this manner, the voltage of the entire circuit can be lowered. This allows the ripple component of the current that depends on the switching period of the half-bridge circuit to be reduced while maintaining the ripple current flowing through the first storage battery 31 and the second storage battery 32. Note that the connection is not limited to the negative terminal of the first storage battery 31 and the negative terminal of the second storage battery 32. It is sufficient that the positive terminal of one of the first storage battery 31 and the second storage battery 32 is electrically connected to the high-potential-side electrical path 22H and the negative terminal of the other is electrically connected to the high-potential-side electrical path 22H.

[0065] In the equivalent circuit shown in FIG. 5 , the same magnitude of ripple current flows through the first storage battery 31 and the second storage battery 32. Therefore, if the first storage battery 31 and the second storage battery 32 have the same internal resistance, the first storage battery 31 and the second storage battery 32 will generate the same amount of heat. This is useful when there is a voltage difference between the two storage batteries, as in this embodiment. The reason for this is explained below. Consider a case where there is a voltage difference between the two storage batteries and current flows through each of the two storage batteries, as in the above-mentioned conventional technology. It is known that the amount of heat generated is proportional to the square of the inverse ratio of the voltage. Therefore, if there is a voltage difference between the two storage batteries, the amount of heat generated will be significantly different. In this regard, according to this embodiment, the same magnitude of ripple current flows through the first storage battery 31 and the second storage battery 32. Therefore, even if there is a voltage difference between the first storage battery 31 and the second storage battery 32, the amount of heat generated will be the same, and the occurrence of a temperature difference will be suppressed.

[0066] Not only in the equivalent circuit, but also in the circuit configuration shown in Fig. 4, the occurrence of a temperature difference between the two storage batteries is suppressed. In the configuration shown in Fig. 4, the control device 100 turns off the inter-battery switch 40 and the low-potential-side main switch SMRL, and turns on the high-potential-side main switch SMRH, the negative-electrode bypass switch 50, the motor-side switch 60, and the connection switch 80, and then performs switching. As a result, ripple currents of the same magnitude flow through a closed circuit including the motor-side electrical path 25, the second storage battery 32, the low-potential-side electrical path 22L, the negative-electrode bypass switch 50, the first storage 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 storage battery 31 and the second storage battery 32, the amount of heat generated is the same, and the occurrence of a 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 utilizing such existing equipment, there is no need to add new equipment, which contributes to reducing the weight and cost of the vehicle.

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

[0069] <Modification of 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 request a temperature increase. However, there may be cases where only one of the storage batteries has a low temperature and requests a temperature increase. For example, consider a case where only the first storage battery 31 requests a temperature increase. In this case, the control device 100 may be configured to control the on / off states of each switch as shown in FIG. 11 to allow current to flow only to the first storage battery 31. Specifically, in FIG. 11 , the high-side main switch SMRH, the inter-battery switch 40, the motor-side switch 60, and the connection switch 80 are in the on state, and the low-side main switch SMRL, the pre-charge switch SP, the negative-electrode bypass switch 50, the high-side charging switch DCRH, and the low-side charging switch DCRL are in the off state.

[0070] In the on / off state shown in Figure 11, current flows through a closed circuit including the first storage 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 battery-to-battery switch 40, and only the first storage battery 31 can be heated.

[0071] Second Embodiment The second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in FIG. 12 , the power conversion device includes a positive electrode-to-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, but does not include the negative electrode-to-negative electrode bypass switch 50 shown in FIG. 1 . The power conversion device also 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 neutral point capacitor 90 shown in FIG. 1 . The motor-side electrical path 25 connects the neutral point of the armature winding 11 and a portion of the inter-battery electrical path 24 that is closer to the first storage battery 31 than the inter-battery switch 40. A motor-side switch 61 is provided in the motor-side electrical path 25.

[0072] The control device 100 turns on the low-side main switch SMRL, the positive-electrode bypass switch 51, the motor-side switch 61, and the connection switch 80, and turns off the high-side main switch SMRH, the pre-charge switch SP, the inter-battery switch 40, the high-side charging switch DCRH, and the low-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 to vary the on-state time. As a result, a ripple current flows in a closed circuit including the first storage battery 31, the high-side electrical path 22H, the positive-electrode bypass switch 51, the second storage battery 32, the low-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 magnitude of ripple current flows through the first storage battery 31 and the second storage battery 32, the first storage battery 31 and the second storage battery 32 are heated, and even if there is a voltage difference between the first storage battery 31 and the second storage battery 32, the amount of heat generated is the same, and the occurrence of temperature differences is also suppressed.

[0073] An equivalent circuit when the switches in the circuit shown in Fig. 12 are turned on and off as described above is shown in Fig. 13. In Fig. 13, the positions of the third storage battery 33 and the neutral point capacitor 90 are swapped compared to the equivalent circuit shown in Fig. 6. That is, in Fig. 13, the high-potential side electrical path and the second end of the armature winding 11 are electrically connected via the neutral point capacitor 90, and the low-potential side electrical path and the second end of the armature winding 11 are electrically connected via the third storage battery 33. In the equivalent circuit of Fig. 13, as in the equivalent circuit of Fig. 6, a ripple current can flow between the third storage battery 33 and the neutral point capacitor 90 via the armature winding 11.

[0074] <Modification of Second Embodiment> The control device 100 may turn off the inter-positive electrode bypass switch 51, the high potential side electrical path 22H, the pre-charge switch SP, the high potential side charging switch DCRH, and the low potential side charging switch DCRL, and turn on the low potential side electrical path 22L, the inter-battery switch 40, the motor-side switch 61, and the connection switch 80. This causes a ripple current to flow in a closed circuit including the inter-battery switch 40, the second storage 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. This makes it possible to raise the temperature of only the second storage battery 32, for example, when only the second storage battery 32 requests a temperature increase.

[0075] Third Embodiment Hereinafter, a third embodiment will be described with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in Fig. 14 , the power conversion device further includes an inter-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 can, for example, turn on the positive electrode bypass switch 51 and turn off the negative electrode bypass switch 50, the battery switch 40, the motor side switch 60, the connection switch 80, the high potential side main switch SMRH, and the low potential side main switch SMRL, and can charge the second storage battery 32 individually using a low voltage charger.

[0077] Fourth Embodiment A fourth embodiment will be described below with reference to the drawings, focusing on differences from the above-described embodiments. In this embodiment, as shown in Fig. 15, in addition to a switch that connects the neutral point of the armature winding 11 to the negative terminal of the first storage battery 31, a switch that connects the neutral point of the armature winding 11 to the positive terminal of the second storage battery 32 is provided as a motor-side switch.

[0078] A first end of a common path 26 is connected to the neutral point of the armature winding 11. A first end of a first electrical path 27 is connected to a second end of the common path 26, and a second end of the first electrical path 27 is connected to a portion of the inter-battery electrical path 24 closer to the second storage battery 32 than the inter-battery switch 40. A first end of a second electrical path 28 is connected to the second end of the common path 26, and a second end of the second electrical path 28 is connected to a portion of the inter-battery electrical path 24 closer to the first storage 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. It is also possible to omit the common path 26 and have the first ends of the first electrical path 27 and the second electrical path 28 connected to the neutral point of the armature winding 11.

[0079] According to the present embodiment described above, the processing shown in FIG. 2 and the processing shown in FIG. 3 can be performed in the circuit configuration shown in FIG.

[0080] Fifth Embodiment Hereinafter, a fifth embodiment will be described with reference to the drawings, focusing on differences from the second embodiment. In this embodiment, as shown in Fig. 16 , 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 can, for example, turn on the negative electrode bypass switch 50 and turn off the positive electrode bypass switch 51, the battery switch 40, the motor side switch 60, the connection switch 80, the high potential side main switch SMRH, and the low potential side main switch SMRL, and can charge the first storage battery 31 individually using a low voltage charger.

[0082] Sixth Embodiment A sixth embodiment will be described below with reference to the drawings, focusing on differences from the above-described embodiments. In this embodiment, as shown in Fig. 17 , a motor-side switch is provided that connects the neutral point of the armature winding 11 to the negative terminal of the first storage battery 31, and also a switch that connects the neutral point of the armature winding 11 to the positive terminal of the second storage battery 32.

[0083] A first end of a common path 26 is connected to the neutral point of the armature winding 11. A first end of a first electrical path 27 is connected to a second end of the common path 26, and a second end of the first electrical path 27 is connected to a portion of the inter-battery electrical path 24 closer to the second storage battery 32 than the inter-battery switch 40. A first end of a second electrical path 28 is connected to the second end of the common path 26, and a second end of the second electrical path 28 is connected to a portion of the inter-battery electrical path 24 closer to the first storage 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. It is also possible to omit the common path 26 and have the first ends of the first electrical path 27 and the second electrical path 28 connected to the neutral point of the armature winding 11.

[0084] According to the present embodiment described above, the processing shown in FIG. 2 and the processing shown in FIG. 3 can be performed in the circuit configuration shown in FIG.

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

[0086] The switches of the inverter 20 are not limited to IGBTs with freewheel diodes connected in reverse parallel, but may be, for example, N-channel MOSFETs with body diodes. In this case, the high-potential terminal of the N-channel MOSFET serves as the drain, and the low-potential terminal serves as the source.

[0087] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0088] The following describes characteristic configurations extracted from the above-described embodiments. [Configuration 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 to the upper arm switch and the lower arm switch; a coil (11) having a first end 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; 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 and a second end of the coil electrically connected via the second capacitor; and the other of the high-potential side electrical path and the low-potential side electrical path and the second end of the coil electrically connected via a power storage unit (33); and a control unit (100) that switches the upper arm switch and the lower arm switch. [Configuration 2] The power conversion device according to Configuration 1, wherein the storage unit is composed of a first storage unit (31) and a second storage unit (32) connected in series, and a negative terminal side of the first storage unit is connected to a negative terminal side of the second storage unit.[Configuration 3] The power storage unit electrical path (24) further includes an inter-power storage unit switch (40) provided in an inter-power storage unit electrical path (24) that electrically connects the negative terminal of the first power storage unit and the positive terminal of the second power storage unit; an inter-negative pole bypass switch (50) that electrically connects the negative 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) that electrically connects the coil and the inter-power storage unit electrical path; a connection switch (80) provided in the coil-side electrical path on the connection point side of the coil-side switch; a high-potential-side switch (SMRH) provided in the high-potential-side electrical path between a connection point with the upper arm switch and a connection point with the positive terminal of the first power storage unit; and a low-potential-side switch (SMRL) provided in the low-potential-side electrical path between a connection point with the lower arm switch and a connection point with the negative terminal of the second power storage unit, The power conversion device according to configuration 2, wherein the coil-side electrical path is a path that electrically connects the coil and a portion of the inter-power-storage-unit electrical path that is closer to the second power storage unit than the inter-power-storage-unit switch, and the control unit performs the switching after turning off the inter-power-storage-unit switch and the low-potential-side switch and turning on the high-potential-side switch, the inter-negative-pole bypass switch, the coil-side switch and the connection switch. [Configuration 4] The power conversion device according to configuration 3, wherein the control unit performs the switching after turning off the inter-negative-pole bypass switch and the low-potential-side switch and turning on the high-potential-side switch, the inter-power-storage-unit switch, the coil-side switch and the connection switch.[Configuration 5] The power storage device further includes: an inter-power storage unit switch (40) provided in an inter-power storage unit electrical path (24) that electrically connects the negative terminal of the first power storage unit and the positive terminal of the second power storage unit; an inter-positive electrode bypass switch (51) that electrically connects the positive 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) that electrically connects the coil and the inter-power storage unit electrical path; a connection switch (80) provided in the coil-side electrical path on the connection point side of the coil-side switch; a high-potential-side switch (SMRH) provided in the high-potential-side electrical path between a connection point with the upper arm switch and a connection point with the positive terminal of the first power storage unit; and a low-potential-side switch (SMRL) provided in the low-potential-side electrical path between a connection point with the lower arm switch and a connection point with the negative terminal of the second power storage unit, The power conversion device according to configuration 2, wherein the coil-side electrical path is a path that electrically connects the coil and 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, and the control unit performs the switching after turning off the inter-power-storage-unit switch and the high-potential-side switch and turning on the low-potential-side switch, the inter-positive-pole bypass switch, the coil-side switch and the connection switch. [Configuration 6] The power conversion device according to configuration 5, wherein the control unit performs the switching after turning off the inter-positive-pole bypass switch and the high-potential-side switch and turning on the low-potential-side switch, the inter-power-storage-unit switch, the coil-side switch and the connection switch. [Configuration 7] The power conversion device according to any one of configurations 3 to 6, further comprising a determination unit that determines whether a temperature increase request is present for at least one of the first power storage unit and the second power storage unit, and the control unit performs the switching when the determination unit determines that the temperature increase request is present. [Configuration 8] The power conversion device according to any one of configurations 1 to 7, wherein a motor (10) electrically connected to the connection point is used as the coil.[Configuration 9] The power conversion device according to any one of configurations 3 to 8, wherein 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. [Configuration 10] The power conversion device according to any one of configurations 3 to 9, wherein the control unit turns on the connection switch when it determines that the voltage of the first capacitor has become equal to a voltage difference between the voltage of the first power storage unit and the voltage of the second power storage unit. [Configuration 11] A program applicable to a power conversion device including: 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 electrically connected to a connection point of 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; 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 and a second end of the coil electrically connected via the second capacitor; and the other of the high potential side electrical path and the low potential side electrical path and a second end of the coil electrically connected via a power storage unit (33); and a computer (101), the program causing the computer to execute a process of switching the upper arm switch and the lower arm switch.

[0089] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. 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 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; 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 a 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 a second end side of the coil via a power storage unit (33); The storage unit is composed of a first storage unit (31) and a second storage unit (32) connected in series, a positive electrode terminal side of one of the first power storage unit and the second power storage unit is electrically connected to the high potential side electrical path, and a negative electrode terminal side of the other of the first power storage unit and the second power storage unit is electrically connected to the high potential side electrical path, A power conversion device comprising a control unit (100) that switches the upper arm switch and the lower arm switch.

2. an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects a negative electrode terminal of the first storage unit and a positive electrode terminal of the second storage unit; a negative electrode bypass switch (50) that electrically connects the negative electrode terminals of the first power storage unit and the second power storage unit to each other; a coil side switch (60) provided in a coil side electrical path (25) that electrically connects the coil and the electrical path between the power storage unit; a connection switch (80) provided on the coil side electrical path closer to the connection point than the coil side switch; a high potential side switch (SMRH) provided in the high potential side electrical path between a connection point with the upper arm switch and a connection point with a positive electrode terminal of the first storage unit; a low potential side switch (SMRL) provided in the low potential side electrical path between a connection point with the lower arm switch and a connection point with a negative electrode terminal of the second storage unit, the coil side electrical path is a path that electrically connects the coil and a portion of the inter-power storage unit electrical path that is located on the second power storage unit side with respect to the inter-power storage unit switch, The control unit is 2. The power conversion device according to claim 1, wherein the switching is performed after turning off the inter-storage unit switch 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.

3. 3. The power conversion device according to claim 2, wherein the control unit performs the switching after turning off the negative electrode bypass switch and the low potential side switch and turning on the high potential side switch, the power storage unit switch, the coil side switch, and the connection switch.

4. an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects a negative electrode terminal of the first storage unit and a positive electrode terminal of the second storage unit; a positive electrode bypass switch (51) that electrically connects the positive electrode terminals of the first storage unit and the second storage unit to each other; a coil side switch (61) provided in a coil side electrical path (25) that electrically connects the coil and the electrical path between the power storage unit; a connection switch (80) provided on the coil side electrical path closer to the connection point than the coil side switch; a high potential side switch (SMRH) provided in the high potential side electrical path between a connection point with the upper arm switch and a connection point with a positive electrode terminal of the first storage unit; a low potential side switch (SMRL) provided in the low potential side electrical path between a connection point with the lower arm switch and a connection point with a negative electrode terminal of the second storage unit, the coil side electrical path is a path that electrically connects the coil and a portion of the inter-power storage unit electrical path that is located on the first power storage unit side with respect to the inter-power storage unit switch, The control unit is 2. The power conversion device according to claim 1, wherein the switching is performed 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.

5. 5. The power conversion device according to claim 4, wherein the control unit performs the switching after turning off the positive electrode bypass switch and the high potential side switch and turning on the low potential side switch, the power storage unit switch, the coil side switch, and the connection switch.

6. a determination unit that determines whether or not 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 power conversion device according to any one of claims 2 to 5, wherein the control unit performs the switching when the determination unit determines that there is a temperature increase request.

7. 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 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; 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 a 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 a second end side of the coil via a power storage unit (33); A motor (10) electrically connected to the connection point is used as the coil, A power conversion device comprising a control unit (100) that switches the upper arm switch and the lower arm switch.

8. The power conversion device according to any one of claims 2 to 5, wherein the control unit changes an amplitude of a current flowing through at least one of the first storage unit and the second storage unit based on a temperature of at least one of the first storage unit and the second storage unit.

9. The control unit is The power conversion device according to any one of claims 2 to 5, wherein when it is determined that the voltage of the first capacitor has become equal to a voltage difference between the voltage of the first storage unit and the voltage of the second storage unit, the connection switch is turned on.

10. 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 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; A low potential side electrical path (22L) electrically connected to the lower arm switch; A computer (101); A program applied to a power conversion device comprising: one of the high potential side electrical path and the low potential side electrical path is electrically connected to a 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 a second end side of the coil via a power storage unit (33); The storage unit is composed of a first storage unit (31) and a second storage unit (32) connected in series, a positive electrode terminal side of one of the first power storage unit and the second power storage unit is electrically connected to the high potential side electrical path, and a negative electrode terminal side of the other of the first power storage unit and the second power storage unit is electrically connected to the high potential side electrical path, The computer includes: A program that executes a process for switching the upper arm switch and the lower arm switch.

11. 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 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; A low potential side electrical path (22L) electrically connected to the lower arm switch; A computer (101); A program applied to a power conversion device comprising: one of the high potential side electrical path and the low potential side electrical path is electrically connected to a 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 a second end side of the coil via a power storage unit (33); A motor (10) electrically connected to the connection point is used as the coil, The computer includes: A program that executes a process for switching the upper arm switch and the lower arm switch.

12. 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 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; A low potential side electrical path (22L) electrically connected to the lower arm switch; A control method applied to a power conversion device comprising: one of the high potential side electrical path and the low potential side electrical path is electrically connected to a 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 a second end side of the coil via a power storage unit (33); The storage unit is composed of a first storage unit (31) and a second storage unit (32) connected in series, a positive electrode terminal side of one of the first power storage unit and the second power storage unit is electrically connected to the high potential side electrical path, and a negative electrode terminal side of the other of the first power storage unit and the second power storage unit is electrically connected to the high potential side electrical path, A control method comprising a step of switching the upper arm switch and the lower arm switch.

13. 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 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; A low potential side electrical path (22L) electrically connected to the lower arm switch; A control method applied to a power conversion device comprising: one of the high potential side electrical path and the low potential side electrical path is electrically connected to a 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 a second end side of the coil via a power storage unit (33); A motor (10) electrically connected to the connection point is used as the coil, A control method comprising a step of switching the upper arm switch and the lower arm switch.