Power conversion device and program

Abstract

This power conversion device is provided with: a high-potential-side electrical path (22H) that can be electrically connected to the positive electrode terminal of a first power storage unit (31); a low-potential-side electrical path (22L) that can be electrically connected to the negative electrode terminal of the second power storage unit (32); an inverter (20); and a motor (10). This power conversion device is provided with: an inter-power-storage-unit switch (40) provided in an inter-power-storage-unit electrical path (24) that electrically connects the negative electrode terminal of a first power storage unit and the positive electrode terminal of a second power storage unit; bypass switches (50, 51) for electrically connecting the negative electrode terminals of the first and second power storage units and / or electrically connecting the positive electrode terminals of the first and second power storage units; and a control unit (100) that determines whether or not the other of the inter-power-storage-unit switch and the bypass switch is fixed to be turned on before turning on the other of the inter-power-storage-unit switch and the bypass switch.

Description

Citation of related applications

[0001] This application is based on Japanese Patent Application No. 2022-144021 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, there is known a control device that determines whether a switch in a power conversion device is fixedly turned on when an external charger is used to charge a vehicle-mounted battery. For example, the control device described in Patent Document 1 sends an on command to the switch to be determined and checks the voltage across the switch. At this time, the control device determines that the switch is fixedly turned on when the voltage across the switch is the same. Prior art literature Patent Literature

[0004] Patent Document 1: U.S. Patent No. 11245346 Summary of the invention

[0005] When switches in a power conversion device are connected in parallel, if one switch is turned on while the other switch is fixedly turned on, a short-circuit current flows between the switches.

[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 suppressing the flow of a short-circuit current between switches.

[0007] The present invention discloses a power conversion device, comprising: a high potential side electrical path electrically connectable to the positive terminal of the first power storage unit; a low potential side electrical path electrically connectable to the negative terminal of the second power storage unit; an inverter including an upper arm switch electrically connected to the high potential side electrical path and a lower arm switch electrically connected to the low potential side electrical path; and a motor electrically connected to a connection point between the upper arm switch and the lower arm switch, The power conversion device includes: an inter-storage unit switch provided in an inter-storage unit electrical path electrically connecting a negative terminal of the first storage unit and a positive terminal of the second storage unit; a bypass switch that performs at least one of an electrical connection between negative terminals of the first power storage unit and the second power storage unit and an electrical connection between positive terminals of the first power storage unit and the second power storage unit; and The control unit determines whether or not the switch between the power storage units and the bypass switch is fixedly turned on before turning on the other switch.

[0008] According to the above configuration, when it is determined that one of the switches is fixedly turned on, the other switch is not turned on, so that the short-circuit current can be suppressed from flowing between the switches. 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 It is a diagram showing the operation mode of the switch during low-voltage charging. Figure 3 It is a diagram showing the operation mode of the switch during high-voltage charging. Figure 4 It is a diagram showing the operation mode of the switch during high-voltage charging. Figure 5 It is a diagram illustrating the mechanism of short-circuit current generation. Figure 6 It is a diagram for explaining the determination method of on-fixing using the smoothing capacitor according to the first embodiment. Figure 7 It is a diagram for explaining the determination method of on-fixing using the smoothing capacitor according to the first embodiment. Figure 8 It is a diagram for explaining the determination method of on-fixing using the smoothing capacitor according to the first embodiment. Fig. 9 This is a flowchart for explaining an operation example of the control device according to the first embodiment. Fig.10 It is a diagram for explaining a method for determining whether the smoothing capacitor is on and fixed according to the second embodiment. Fig.11 It is a diagram for explaining a method for determining whether the smoothing capacitor is on and fixed according to the second embodiment. Fig.12 It is a diagram for explaining a method for determining whether the smoothing capacitor is on and fixed according to the second embodiment. Fig.13 This is a flowchart for explaining an operation example of the control device according to the second embodiment. Fig.14 It is a diagram for explaining the method of determining whether the on-state is fixed according to the third embodiment. Fig.15 This is a flowchart for explaining an operation example of the control device according to the third embodiment. Fig.16 This is a flowchart for explaining an operation example of the control device according to the third embodiment. Fig.17 This is a flowchart for explaining an operation example of the control device according to the third embodiment. Fig.18 This is a flowchart for explaining an operation example of the control device according to the third embodiment. Fig.19 This is a flowchart for explaining an operation example of the control device according to the fourth embodiment. Fig. 20 This is a flowchart for explaining an operation example of the control device according to the fourth embodiment. Fig.21 This is a flowchart for explaining an operation example of the control device according to the fourth embodiment. Fig. 22 This is a flowchart for explaining an operation example of the control device according to the fourth embodiment. Fig.23 This is a flowchart for explaining an operation example of the control device according to the fourth embodiment. Fig.24 This is a flowchart for explaining an operation example of the control device according to the fourth embodiment. Fig.25 It is a diagram showing the overall configuration of the system according to the fifth embodiment. Fig.26 This is a flowchart for explaining an operation example of the control device according to the fifth embodiment. Fig. 27 This is a flowchart for explaining an operation example of the control device according to the modification example of the fifth embodiment. Fig.28 It is an overall structural diagram of the system according to the sixth embodiment. Fig.29 This is a flowchart for explaining an operation example of the control device according to the sixth embodiment. Fig.30 This is a flowchart for explaining an operation example of the control device according to the sixth embodiment. Fig.31 This is a flowchart for explaining an operation example of the control device according to the sixth embodiment. Fig.32 This is a flowchart for explaining an operation example of the control device according to the sixth embodiment. Fig.33 It is an overall structural diagram of the system according to the seventh embodiment. Fig.34 It is an overall structural diagram of the system according to the eighth embodiment. Fig.35 It is an overall structural diagram of the system according to the ninth embodiment. Fig.36It is an overall structural diagram of the system according to the tenth 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, having a star-connected U-phase, V-phase, and W-phase armature winding 11 and a rotor not shown. The armature winding 11 of each phase is arranged in a manner that the electrical angle is staggered by 120°. 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 causes the vehicle to move.

[0013] The inverter 20 includes a series connection of three corresponding upper arm switches SWH and lower arm switches SWL. An upper arm diode DH as a freewheeling diode is connected in reverse parallel to the upper arm switch SWH, and a lower arm diode DL as a freewheeling diode is connected in reverse parallel to the lower arm switch SWL. In the present embodiment, each switch SWH, 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 also be provided outside the inverter 20. The voltage of the smoothing capacitor 21 is detected by the SC voltage sensor 19.

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

[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 becomes 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 200V. However, it is not limited to this, as long as the terminal voltage of the first battery 31 is greater than the terminal voltage of the second battery 32. Battery cells are, for example, secondary batteries such as lithium-ion batteries.

[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 has a main switch for electrically connecting or disconnecting the first and second storage batteries 31 and 32 with 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 with 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 in the disconnected state and allows the flow of bidirectional current in the connected state. In the high potential side electrical path 22H, a high potential side main switch SMRH and a 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 as 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 in the off state, and allow the flow of bidirectional current in the on state.

[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. When the inter-battery switch 40 is in the on state, 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 in the off state, 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 to the low potential side electrical path 22L. When the negative electrode bypass switch 50 is in the on state, the negative terminal of the first battery 31 is electrically connected to the negative terminal of the second battery 32. On the other hand, when the negative electrode bypass switch 50 is in the off state, the negative terminal of the first battery 31 is electrically disconnected from the negative terminal of the second battery 32.

[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 to 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. When the motor-side switch 60 and the connection switch 80 are in the on state, the neutral point of the armature winding 11 and the positive terminal of the second battery 32 are electrically connected. On the other hand, when the motor-side switch 60 and the connection switch 80 are in the off state, 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 to a portion of the inter-battery electrical path 24 closer to the second battery 32 side than the inter-battery switch 40.

[0024] The power conversion device has 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 has 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. In addition, as other sensors, the power conversion device has 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 of them. 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. The program includes, for example, the following Fig. 9The program for performing the processing shown in the above-mentioned program is executed by executing the program. The storage unit is, for example, a nonvolatile memory. In addition, the program stored in the storage unit can be updated via, for example, OTA (Over The Air) or a communication network such as the Internet.

[0026] The control device 100 performs opening and closing control of each switch SWH and SWL constituting the inverter 20 based on the detection value of each sensor, so as 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 portion of the high potential side electrical path 22H and the negative electrode side connection portion 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 200 or a high voltage charger 210 (see Figure 2 to Figure 4 The charging voltage of the low voltage charger 200 is a voltage lower than the voltage between the terminals of the series connection of the first and second storage batteries 31 and 32 (specifically, the rated voltage), for example, 400V.

[0028] The charging voltage of the high-voltage charger 210 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 disconnecting the high potential side charging switch DCRH and the low potential side charging switch DCRL, 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 neutral point capacitor 90 is provided with an NC voltage sensor 75 for detecting the voltage of the 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 is generated due to switching. The neutral point capacitor 90 is provided to suppress the high-frequency current generated due to switching from the inverter 20 side to flow into the first and second batteries 31, 32 and the external charger.

[0031] The low potential side main switch SMRL is connected in parallel to a series connection of a precharge switch SP and a resistor 95. The precharge switch SP is used in a precharge process for charging the smoothing capacitor 21 or the neutral point capacitor 90, for example, when the power converter is started.

[0032] Next, refer to Figure 2 to Figure 4 , the on / off status of each switch when the system is connected to an external charger and charging is described. Figure 2 In the following drawings, illustration of the control device 100 and the SC voltage sensor 19 is omitted.

[0033] Figure 2 2 shows the on / off states of the switches when the external charger connected to the connection portions of the electrical paths 22H and 22L is the low voltage charger 200. Figure 2 As shown, when connected to the low-voltage charger 200, the control device 100 operates the main switches SMRH, SMRL, the inter-battery switch 40, the negative electrode bypass switch 50, the motor side switch 60, the connecting switch 80 and the upper and lower arm switches SWH, SWL of the inverter 20, so that the first battery 31 is connected in parallel with the low-voltage charger 200, and the second battery 32 is connected in parallel with the low-voltage charger 200 via the inverter 20 and the armature winding 11.

[0034] Specifically, the control device 100 turns on the main switches SMRH, SMRL, the negative electrode bypass switch 50, the motor side switch 60, and the connection switch 80, and turns off the inter-battery switch 40. In addition, the control device 100 turns off the lower arm switches SWL of all phases of the inverter 20, and repeatedly turns on and off the upper arm switch SWH of at least one phase. Figure 2As shown, the first battery 31 is connected in parallel with the low-voltage charger 200, and the second battery 32 is connected in parallel with the low-voltage charger 200 via the inverter 20 and the armature winding 11. Therefore, the current flows in a closed circuit including the low-voltage charger 200, the high-potential side electrical path 22H, the first battery 31, the negative electrode bypass switch 50 and the low-potential side electrical path 22L, and the first battery 31 is charged. In addition, the current flows in a closed circuit including the low-voltage charger 200, the high-potential side electrical path 22H, the upper arm switch SWH, the armature winding 11, the neutral point, the connection switch 80, the motor side switch 60, the second battery 32 and the low-potential side electrical path 22L, and the second battery 32 is stepped down and charged. In addition, when the upper arm switches SWH of multiple phases are turned on, the impedance of the charging path can be reduced. In this embodiment, Figure 2 The mode in which charging is performed in the switching state shown is called "parallel mode".

[0035] Figure 3 2 shows the on / off states of the switches when the external charger connected to the connection portions of the electrical paths 22H and 22L is the high voltage charger 210. Figure 3 As shown, when connected to the high-voltage charger 210, the control device 100 operates the main switches SMRH, SMRL, the inter-battery switch 40, the negative electrode bypass switch 50, the motor side switch 60, the connecting switch 80 and the upper and lower arm switches SWH, SWL of the inverter 20 to achieve a state in which the first battery 31 and the second battery 32 are connected in series relative to the high-voltage charger 210.

[0036] Specifically, the control device 100 turns on the main switches SMRH, SMRL and the inter-battery switch 40, and turns off the inter-negative bypass switch 50, the motor side switch 60, the connection switch 80, and the upper and lower arm switches SWH, SWL of all phases of the inverter 20. Figure 3 As shown, the first battery 31 and the second battery 32 are connected in series with respect to the high-voltage charger 210. Therefore, current flows in a closed circuit including the high-voltage charger 210, the high-potential side electrical path 22H, the first battery 31, the inter-battery switch 40, the second battery 32 and the low-potential side electrical path 22L, and the first battery 31 and the second battery 32 are charged in a state of being connected in series. At this time, the upper arm switch SWH, the connecting switch 80 and the motor side switch 60 of the inverter 20 are disconnected, so that the charging current of the high-voltage charger 210 can be prevented from flowing through the inverter 20 and the armature winding 11. In the present embodiment, Figure 3 The mode in which charging is performed in the switching state shown is called "series mode".

[0037] Figure 4 also with Figure 3 Similarly, the on / off states of the switches when the external charger connected to the connection portions of the electrical paths 22H and 22L is the high-voltage charger 210 are shown. Figure 3 Same, but in Figure 4 The on / off status of each switch is Figure 3 different.

[0038] exist Figure 4 In the embodiment, the control device 100 turns on the main switches SMRH, SMRL, the inter-battery switch 40, the motor side switch 60 and the connection switch 80, and turns off the inter-negative electrode bypass switch 50. Figure 4 As shown, the first battery 31 and the second battery 32 are connected in series with respect to the high-voltage charger 210. As a result, current flows in a closed circuit including the high-voltage charger 210, the high-potential side electrical path 22H, the first battery 31, the inter-battery switch 40, the second battery 32 and the low-potential side electrical path 22L, and the first battery 31 and the second battery 32 are charged in a state of being connected in series. In addition, the control device 100 alternately turns on the upper and lower arm switches SWH and SWL of the inverter. As a result, current flows in a closed circuit including the high-voltage charger 210, the high-potential side electrical path 22H, the upper arm switch SWH, the armature winding 11, the neutral point, the connecting switch 80, the motor side switch 60, the second battery 32 and the low-potential side electrical path 22L, and the second battery 32 is charged. In the present embodiment, Figure 4 The mode in which charging is performed in the switching state shown is called "series neutral point mode".

[0039] Next, refer to Figure 5 (a) to (b) of the present invention describe the case where either the inter-battery switch 40 or the inter-negative bypass switch 50 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 having contacts, when an arc is generated accompanying 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.

[0040] exist Figure 5 In (a), the system is not connected to an external charger and all switches are in the OFF state. However, the inter-battery switch 40 is fixedly turned on and will not be in the OFF state even if a OFF command is received from the control device 100. In this state, for example, if a low-voltage charger 200 is connected, Figure 2As described in the above, the negative electrode bypass switch 50 is turned on. At this time, the inter-battery switch 40 is turned on and fixed, so Figure 5 As shown in (b) of FIG. 1 , the short-circuit current flows in the closed circuit including the inter-battery switch 40 , the inter-negative electrode bypass switch 50 , and the second storage battery 32 .

[0041] exist Figure 5 In (a) to (b) of FIG. 1 , an example in which the inter-battery switch 40 is fixedly turned on is described. However, the same is true when the inter-battery bypass switch 50 is fixedly turned on instead of the inter-battery switch 40. That is, when the inter-battery bypass switch 50 is fixedly turned on, for example, when the high-voltage charger 210 is connected, Figure 3 , 4 As described in , the inter-battery switch 40 is turned on. As a result, the short-circuit current flows in a closed circuit including the inter-battery switch 40, the inter-negative electrode bypass switch 50, and the second storage battery 32. Therefore, in any of the parallel mode, the series mode, and the series neutral point mode, when charging is performed, either the inter-battery switch 40 or the inter-negative electrode bypass switch 50 is turned on, so it is necessary to determine whether the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are turned on before charging starts or after charging is completed.

[0042] Next, refer to Figures 6 to 8 An example of a method for determining whether the connection is fixed will be described. Here, a method for determining whether the connection is fixed using the voltage of the smoothing capacitor 21 will be described. Hereinafter, the voltage of the smoothing capacitor 21 detected by the SC voltage sensor 19 will be referred to as voltage Vinv. Figures 6 to 8 The on / off state of each switch in the figure represents the on / off state of the power conversion device when it is started, that is, before charging begins. Figure 6 As shown, when the power conversion device is started, the high potential side main switch SMRH and the low potential side main switch SMRL are turned on. In addition, the pre-charge switch SP may be turned on instead of the low potential side main switch SMRL. That is, the "low potential side switch provided between the lower arm switch and the negative terminal of the second power storage unit in the low potential side electrical path" includes the low potential side main switch SMRL and the pre-charge switch SP.

[0043] The inter-battery switch 40, the inter-negative electrode bypass switch 50, the motor side switch 60, and the connection switch 80 are in the OFF state. Since the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are in the OFF state, the current does not flow through the smoothing capacitor 21, and therefore the voltage Vinv of the smoothing capacitor 21 is 0 V. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0 V when the main switches SMRH and SMRL are turned on at the start of the power conversion device, it determines that the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not turned on and fixed.

[0044] Figure 7 also with Figure 6 Similarly, when the power conversion device is started, the main switches SMRH and SMRL are turned on. Figure 7 and Figure 6 The difference is that the inter-battery switch 40 is turned on and fixed. At this time, the first battery 31 and the second battery 32 are connected in series. As a result, current flows in a closed circuit including the second battery 32, the inter-battery switch 40, the first battery 31, the high-potential side electrical path 22H, the smoothing capacitor 21, and the low-potential side electrical path 22L, and the voltage Vinv of the smoothing capacitor 21 becomes the sum of the voltages of the first battery 31 and the second battery 32, that is, 600V. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 when the main switches SMRH and SMRL are turned on is equal to the sum of the voltages of the first battery 31 and the second battery 32 at the start of the power conversion device, it determines that the inter-battery switch 40 is turned on and fixed.

[0045] Figure 8 also with Figure 6 Similarly, when the power conversion device is started, the main switches SMRH and SMRL are turned on. Figure 8 and Figure 6 The difference is that the negative electrode bypass switch 50 is fixedly turned on. In this case, the current flows in the closed circuit including the negative electrode bypass switch 50, the first storage battery 31, the high potential side electrical path 22H, the smoothing capacitor 21, and the low potential side electrical path 22L, and the voltage Vinv of the smoothing capacitor 21 is the same as that of the first storage battery 31, that is, 400 V. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 when the main switches SMRH and SMRL are turned on is equal to the voltage of the first storage battery 31 when the power conversion device is started, it determines that the negative electrode bypass switch 50 is fixedly turned on.

[0046] Next, refer to Fig. 9The flowchart of FIG. 1 is used to illustrate an operation example of the control device 100. The initial state of each switch at the start time of the flowchart is a state in which a disconnection instruction is received from the control device 100. In step S101, the control device 100 selects a charging mode. For example, the mode can be selected according to the type of external charger connected.

[0047] In step S102, the control device 100 turns on the main switches SMRH and SMRL, and obtains the voltage Vinv of the smoothing capacitor 21 detected by the SC voltage sensor 19. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0V, that is, when the processing of step S103 is yes, the processing proceeds to step S104. In step S104, the control device 100 determines that the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not fixed on. The processing proceeds to step S105, and the control device 100 switches the on and off states of each switch based on the charging mode. Thus, charging starts.

[0048] On the other hand, when the processing of step S103 is NO, the processing proceeds to step S106. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the total value (600V) of the voltage of the first storage battery 31 and the voltage of the second storage battery 32, that is, when the processing of step S106 is YES, the processing proceeds to step S107. In step S107, the control device 100 determines that the inter-battery switch 40 is turned on and fixed. The processing proceeds to step S108, and the control device 100 stops charging.

[0049] When the processing of step S106 is No, the processing proceeds to step S109. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage (400V) of the first storage battery 31, that is, when the processing of step S109 is Yes, the processing proceeds to step S110. In step S110, the control device 100 determines that the negative electrode bypass switch 50 is turned on and fixed. Thereafter, the processing proceeds to step S108. In addition, when the processing of step S109 is No, since an unexpected phenomenon may have occurred, the processing proceeds to step S108.

[0050] According to the first embodiment described in detail above, the following effects can be obtained.

[0051] Before turning on either of the inter-battery switch 40 and the inter-negative electrode bypass switch 50, the control device 100 determines whether the other switch is fixedly turned on. If it is determined that one switch is fixedly turned on, the other switch is not turned on, thereby preventing the occurrence of a problem such as Figure 5 As described in , the short-circuit current flows in the closed circuit including the inter-battery switch 40 , the inter-negative electrode bypass switch 50 , and the second storage battery 32 .

[0052] When the power conversion device is started, that is, before charging starts, the control device 100 turns on the main switches SMRH and SMRL, and determines whether the inter-battery switch 40 or the inter-negative electrode bypass switch 50 is turned on based on the voltage Vinv of the smoothing capacitor 21 at this time. According to this structure, it is possible to determine whether the inter-battery switch 40 or the inter-negative electrode bypass switch 50 is turned on without actually turning on or off the inter-battery switch 40 or the inter-negative electrode bypass switch 50.

[0053] When the inter-battery switch 40 or the inter-negative electrode bypass switch 50 is fixedly turned on, the voltage of the smoothing capacitor 21 changes. Therefore, by focusing on the voltage of the smoothing capacitor 21, it is possible to determine which of the inter-battery switch 40 and the inter-negative electrode bypass switch 50 is fixedly turned on.

[0054] <Modification of the first embodiment> ·use Figures 6 to 8 The determination of whether the power conversion device is connected and fixed as described above may be performed not when the power conversion device is started but when the power conversion device is stopped. When the power conversion device is stopped, that is, after charging is completed, each switch is controlled to be in an off state, so that the determination of whether the power conversion device is connected and fixed can be made in the same way as when starting. However, when the power conversion device is stopped, electric charge is accumulated in the smoothing capacitor 21 due to charging. Therefore, in order to determine that the power conversion device is connected and fixed when the power conversion device is stopped, it is necessary to discharge the smoothing capacitor 21 so that the voltage of the smoothing capacitor 21 is 0V. As a method of discharging the smoothing capacitor 21, for example, a method of discharging the smoothing capacitor 21 by passing a d-axis current through the inverter 20 and the motor 10 can be cited. In addition, when the power conversion device is started, the voltage of the smoothing capacitor 21 is 0V, so such a discharge process is not required.

[0055] <Second embodiment> Below, refer to Figures 10 to 13 The second embodiment will be described. The second embodiment differs from the first embodiment in the switch that is the control target when the power conversion device is started. The same structure as the first embodiment is referenced by the reference numerals and the description thereof is omitted. The following description will focus on the differences.

[0056] Fig.10 The on / off status of each switch when the power conversion device is started is shown. Fig.10As shown, when the power conversion device is started, the high potential side main switch SMRH, the motor side switch 60, and the connection switch 80 are turned on. The inter-battery switch 40, the inter-negative bypass switch 50, and the low potential side main switch SMRL are in the off state. Since the inter-battery switch 40 and the inter-negative bypass switch 50 are in the off state, the current does not flow through the smoothing capacitor 21, so the voltage Vinv of the smoothing capacitor 21 is 0V. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0V when the high potential side main switch SMRH, the motor side switch 60, and the connection switch 80 are turned on at the start of the power conversion device, it determines that the inter-battery switch 40 and the inter-negative bypass switch 50 are not fixedly turned on.

[0057] Fig.11 also with Fig.10 Similarly, when the power conversion device is started, the high potential side main switch SMRH, the motor side switch 60 and the connection switch 80 are turned on. Fig.11 and Fig.10 The difference is that the inter-battery switch 40 is fixedly turned on. In this case, the current flows in the closed circuit including the inter-battery switch 40, the first storage battery 31, the high potential side electrical path 22H, the smoothing capacitor 21, the inverter 20, the neutral point of the motor 10, the connection switch 80 and the motor side switch 60, and the voltage Vinv of the smoothing capacitor 21 is the same as that of the first storage battery 31, that is, 400 V. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 when the high potential side main switch SMRH, the motor side switch 60 and the connection switch 80 are turned on is equal to the voltage of the first storage battery 31 when the power conversion device is started, it determines that the inter-battery switch 40 is fixedly turned on.

[0058] Fig.12 also with Fig.10 Similarly, when the power conversion device is started, the high potential side main switch SMRH, the motor side switch 60 and the connection switch 80 are turned on. Fig.12 and Fig.10The difference is that the negative electrode bypass switch 50 is turned on and fixed. At this time, the first battery 31 and the second battery 32 are connected in parallel. As a result, current flows in a closed circuit including the second battery 32, the negative electrode bypass switch 50, the first battery 31, the high potential side electrical path 22H, the smoothing capacitor 21, the inverter 20, the neutral point of the motor 10, the connection switch 80, and the motor side switch 60, and the voltage Vinv of the smoothing capacitor 21 is equal to the voltage difference (200V) between the voltage of the first battery 31 and the voltage of the second battery 32. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 when the high potential side main switch SMRH, the motor side switch 60, and the connection switch 80 are turned on is equal to the voltage difference between the voltage of the first battery 31 and the voltage of the second battery 32 at the start of the power conversion device, it determines that the negative electrode bypass switch 50 is turned on and fixed.

[0059] Next, refer to Fig.13 The flowchart of FIG. 1 is used to describe an operation example of the control device 100. The initial state of each switch at the start time of the flowchart is a state in which an opening instruction is received from the control device 100. In step S201, the control device 100 selects a charging mode.

[0060] In step S202, the control device 100 turns on the high potential side main switch SMRH, the motor side switch 60, and the connection switch 80 to obtain the voltage Vinv of the smoothing capacitor 21. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0V, that is, when the processing of step S203 is yes, the processing proceeds to step S204. In step S204, the control device 100 determines that the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not fixed on. The processing proceeds to step S205, and the control device 100 switches the on and off states of each switch based on the charging mode. Thus, charging starts.

[0061] On the other hand, when the processing of step S203 is No, the processing proceeds to step S206. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage (400V) of the first storage battery 31, that is, when the processing of step S206 is Yes, the processing proceeds to step S207. In step S207, the control device 100 determines that the inter-battery switch 40 is turned on and fixed. The processing proceeds to step S208, and the control device 100 stops charging.

[0062] When the processing of step S206 is No, the processing proceeds to step S209. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage difference (200V) between the voltage of the first battery 31 and the voltage of the second battery 32, that is, when the processing of step S209 is Yes, the processing proceeds to step S210. In step S210, the control device 100 determines that the negative electrode bypass switch 50 is turned on and fixed. Thereafter, the processing proceeds to step S208. In addition, when the processing of step S209 is No, the processing proceeds to step S208 because an unexpected phenomenon may occur.

[0063] According to the second embodiment described in detail above, the following effects can be obtained.

[0064] When the power conversion device is started, that is, before charging starts, the control device 100 turns on the high potential side main switch SMRH, the motor side switch 60, and the connection switch 80, and determines whether the inter-battery switch 40 or the inter-negative electrode bypass switch 50 is fixedly turned on based on the voltage Vinv of the smoothing capacitor 21 at this time. According to this structure, it is possible to determine whether the inter-battery switch 40 or the bypass switch is fixedly turned on without actually turning on or off the inter-battery switch 40 or the inter-negative electrode bypass switch 50.

[0065] When the inter-battery switch 40 or the inter-negative electrode bypass switch 50 is fixedly turned on, the voltage of the smoothing capacitor 21 changes. Therefore, by focusing on the voltage of the smoothing capacitor 21, it is possible to determine which of the inter-battery switch 40 and the inter-negative electrode bypass switch 50 is fixedly turned on.

[0066] <Modification of Second Embodiment> ·use Figures 10-12 The determination of the connection fixation described above may be performed not at the time of the start-up of the power conversion device but at the end of the power conversion device. At the end of the power conversion device, that is, after the charging is completed, each switch is controlled to be in the off state, so the connection fixation can be determined in the same way as at the start-up. However, at the end of the power conversion device, the charge is accumulated in the smoothing capacitor 21 due to the charging. Therefore, in order to determine the connection fixation at the end of the power conversion device, it is necessary to discharge the smoothing capacitor 21 so that the voltage of the smoothing capacitor 21 is 0V. The method of discharging the smoothing capacitor 21 is the same as the modification of the first embodiment.

[0067] <Third embodiment> Below, refer to Fig.14 The third embodiment will be described. The same configuration as the first embodiment is referenced by a reference numeral and its description is omitted. The following description will focus on the differences. Fig.14 : is a structural diagram of a power conversion device according to a third embodiment. Fig.14As shown, the power conversion device includes at least any one of the following: a battery switch voltage sensor 76 for detecting the voltage across the battery switch 40; a bypass switch voltage sensor 77 for detecting the voltage across the negative electrode bypass switch 50; a terminal voltage sensor 78 for detecting the voltage between the positive terminal of the first battery 31 and the positive terminal of the second battery 32, that is, the terminal voltage; and a PN voltage sensor 79 for detecting the voltage between the high potential side electrical path 22H and the low potential side electrical path 22L, that is, the PN voltage.

[0068] The control device 100 determines whether the inter-battery switch 40 or the negative electrode bypass switch 50 is fixed on based on any one of the voltages across the inter-battery switch voltage sensor 76, the voltage across the inter-battery switch voltage sensor 77, the terminal voltage detected by the terminal voltage sensor 78, and the PN voltage detected by the PN voltage sensor 79.

[0069] First, refer to Fig.15 , the method for determining the voltage across the inter-battery switch 40 is first described using the flowchart. In step S301, the control device 100 determines whether the voltage across the inter-battery switch 40 detected by the inter-battery switch voltage sensor 76 is the total value of the voltage of the first storage battery 31 and the voltage of the second storage battery 32, that is, 600V. In the present embodiment, when the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not fixedly turned on and become the open state, the voltage across the inter-battery switch 40 VB becomes the total value of the voltage of the first storage battery 31 and the voltage of the second storage battery 32, that is, 600V. Therefore, when the processing of step S301 is yes, the processing proceeds to step S302, and the control device 100 determines that the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not fixedly turned on.

[0070] On the other hand, when the processing of step S301 is No, the processing proceeds to step S303. In step S303, the control device 100 determines whether the voltage VB across the inter-battery switch 40 is 0 V. In the present embodiment, when the inter-battery switch 40 is turned on and fixed, the voltage VB across the inter-battery switch 40 is 0 V. Therefore, when the processing of step S303 is Yes, the processing proceeds to step S304, and the control device 100 determines that the inter-battery switch 40 is turned on and fixed.

[0071] If the processing of step S303 is negative, the processing proceeds to step S305. In step S305, the control device 100 determines whether the voltage VB across the inter-battery switch 40 is equal to the voltage (200V) of the second storage battery 32. In the present embodiment, when the inter-negative electrode bypass switch 50 is fixedly turned on, the voltage VB across the inter-battery switch 40 is equal to the voltage of the second storage battery 32. Therefore, if the processing of step S305 is positive, the processing proceeds to step S306, and the control device 100 determines that the inter-negative electrode bypass switch 50 is fixedly turned on.

[0072] After steps S304 and S306, the process proceeds to step S307, and the control device 100 stops charging. Also, when the result of the process in step S305 is NO, the process proceeds to step S307.

[0073] Next, refer to Fig.16 , a method for determining the voltage across the negative electrode bypass switch 50 is described using the flowchart of FIG. 1. In step S401, the control device 100 determines whether the voltage across the negative electrode bypass switch 50 detected by the bypass switch voltage sensor 77 is equal to the voltage (400V) of the first storage battery 31. In the present embodiment, when the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not fixedly connected and are in the disconnected state, the voltage across the negative electrode bypass switch 50 VP is equal to the voltage of the first storage battery 31. Therefore, when the processing of step S401 is yes, the processing proceeds to step S402, and the control device 100 determines that the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not fixedly connected.

[0074] On the other hand, when the processing of step S401 is NO, the processing proceeds to step S403. In step S403, the control device 100 determines whether the voltage VP across the inter-negative electrode bypass switch 50 is equal to the voltage (200V) of the second storage battery 32. In the present embodiment, when the inter-battery switch 40 is fixedly turned on, the voltage VP across the inter-negative electrode bypass switch 50 is equal to the voltage of the second storage battery 32. Therefore, when the processing of step S403 is YES, the processing proceeds to step S404, and the control device 100 determines that the inter-battery switch 40 is fixedly turned on.

[0075] When the processing of step S403 is No, the processing proceeds to step S405. In step S405, the control device 100 determines whether the voltage VP across the negative electrode bypass switch 50 is 0 V. In the present embodiment, when the negative electrode bypass switch 50 is fixedly turned on, the voltage VP across the negative electrode bypass switch 50 is 0 V. Therefore, when the processing of step S405 is Yes, the processing proceeds to step S406, and the control device 100 determines that the negative electrode bypass switch 50 is fixedly turned on.

[0076] After steps S404 and S406, the process proceeds to step S407, and the control device 100 stops charging. Also, when the result of the process in step S405 is NO, the process proceeds to step S407.

[0077] Next, refer to Fig.17 , the determination method using the inter-terminal voltage is described. In step S501, the control device 100 determines whether the inter-terminal voltage VT detected by the inter-terminal voltage sensor 78 is equal to the voltage of the second storage battery 32. In the present embodiment, when the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not fixedly turned on and become disconnected, the inter-terminal voltage VT is equal to the voltage of the second storage battery 32. Therefore, when the processing of step S501 is yes, the processing proceeds to step S502, and the control device 100 determines that the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not fixedly turned on.

[0078] On the other hand, when the processing of step S501 is NO, the processing proceeds to step S503. In step S503, the control device 100 determines whether the inter-terminal voltage VT is equal to the voltage of the first storage battery 31. In the present embodiment, when the inter-battery switch 40 is turned on and fixed, the inter-terminal voltage VT is equal to the voltage of the first storage battery 31. Therefore, when the processing of step S503 is YES, the processing proceeds to step S504, and the control device 100 determines that the inter-battery switch 40 is turned on and fixed.

[0079] When the processing of step S503 is NO, the processing proceeds to step S505. In step S505, the control device 100 determines whether the inter-terminal voltage VT is equal to the voltage difference between the voltage of the first storage battery 31 and the voltage of the second storage battery 32. In the present embodiment, when the inter-negative electrode bypass switch 50 is fixedly turned on, the inter-terminal voltage VT is equal to the voltage difference between the voltage of the first storage battery 31 and the voltage of the second storage battery 32. Therefore, when the processing of step S505 is YES, the processing proceeds to step S506, and the control device 100 determines that the inter-negative electrode bypass switch 50 is fixedly turned on.

[0080] After steps S504 and S506, the process proceeds to step S507, and the control device 100 stops charging. Also, when the result of the process in step S505 is NO, the process proceeds to step S507.

[0081] Next, refer to Fig.18, the determination method using the PN voltage is described. In step S601, the control device 100 determines whether the PN voltage VPN detected by the PN voltage sensor 79 is 0V. In the present embodiment, when the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not fixedly closed and are in the open state, the PN voltage VPN is 0V. Therefore, when the processing of step S601 is yes, the processing proceeds to step S602, and the control device 100 determines that the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not fixedly closed.

[0082] On the other hand, when the processing of step S601 is NO, the processing proceeds to step S603. In step S603, the control device 100 determines whether the PN voltage VPN is the sum of the voltage of the first battery 31 and the voltage of the second battery 32, that is, 600 V. In the present embodiment, when the inter-battery switch 40 is turned on and fixed, the PN voltage VPN is the sum of the voltage of the first battery 31 and the voltage of the second battery 32, that is, 600 V. Therefore, when the processing of step S603 is YES, the processing proceeds to step S604, and the control device 100 determines that the inter-battery switch 40 is turned on and fixed.

[0083] When the processing of step S603 is No, the processing proceeds to step S605. In step S605, the control device 100 determines whether the PN voltage VPN is equal to the voltage (400V) of the first storage battery 31. In the present embodiment, when the negative electrode bypass switch 50 is fixedly turned on, the PN voltage VPN is equal to the voltage of the first storage battery 31. Therefore, when the processing of step S605 is Yes, the processing proceeds to step S606, and the control device 100 determines that the negative electrode bypass switch 50 is fixedly turned on.

[0084] After steps S604 and S606, the process proceeds to step S607, and the control device 100 stops charging. Also, when the result of the process in step S605 is NO, the process proceeds to step S607.

[0085] According to the third embodiment described in detail above, the following effects can be obtained.

[0086] When the power conversion device is started, that is, before charging starts, the control device 100 uses any one of the voltages detected by the voltage sensors 76 to 79 to determine whether the inter-battery switch 40 or the inter-negative electrode bypass switch 50 is fixedly closed. According to this configuration, it is possible to determine whether the inter-battery switch 40 or the inter-negative electrode bypass switch 50 is fixedly closed without actually performing an on-operation or an off-operation on the inter-battery switch 40 or the inter-negative electrode bypass switch 50.

[0087] When the inter-battery switch 40 or the inter-negative electrode bypass switch 50 is fixedly turned on, the voltage detected by each voltage sensor 76 to 79 changes. Therefore, by focusing on any one of the voltages detected by each voltage sensor 76 to 79, it is possible to determine which of the inter-battery switch 40 and the inter-negative electrode bypass switch 50 is fixedly turned on.

[0088] <Modification of the third embodiment> ·use Figures 15 to 18 The above-described determination of the on-fixing state may be performed not when the power conversion device is started but when the power conversion device is stopped. When the power conversion device is stopped, that is, after charging is completed, each switch is controlled to an off state, so the on-fixing state can be determined in the same way as when starting.

[0089] <Fourth embodiment> The fourth embodiment is described below. In the previous embodiment, it is described that the inter-battery switch 40 and the inter-negative bypass switch 50 are determined to be connected and fixed, and charging is started when it is determined that the inter-battery switch 40 and the inter-negative bypass switch 50 are not connected and fixed. It is also possible to determine whether the other switches are faulty before starting charging after determining that the inter-battery switch 40 and the inter-negative bypass switch 50 are not connected and fixed. Below, an example of the determination method is described for each of the series mode, the parallel mode, and the series neutral point mode.

[0090] Fig.19 This flowchart is a flow chart in the series mode. This flowchart is a flow chart after it is determined that the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not closed and fixed.

[0091] In step S701, the control device 100 turns on the inter-battery switch 40. Next, in step S702, the control device 100 turns on the precharge switch SP to obtain the voltage Vinv of the smoothing capacitor 21. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0V, that is, when the processing in step S703 is yes, the processing proceeds to step S704.

[0092] In step S704, the control device 100 turns on the high potential side main switch SMRH to obtain the voltage Vinv of the smoothing capacitor 21. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the sum of the voltage of the first storage battery 31 and the voltage of the second storage battery 32, that is, 600V, that is, when the processing in step S706 is yes, the processing proceeds to step S708. In step S708, the control device 100 turns on the low potential side main switch SMRL. Then, in step S709, the control device 100 turns off the pre-charge switch SP. Then, in step S710, the control device 100 starts charging.

[0093] If the result of the process in step S703 is NO, the process proceeds to step S705, and the control device 100 determines that the high potential side main switch SMRH is fixedly turned on. The process proceeds to step S711, and the control device 100 stops charging.

[0094] When the processing of step S706 is No, the processing proceeds to step S707, and 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. The processing proceeds to step S711, and the control device 100 stops charging. The processing of step S706 is No, which means that the control device 100 outputs a turn-on command to the high potential side main switch SMRH in step S704, but the high potential side main switch SMRH is not turned on due to the disconnection fixation.

[0095] Fig. 20 This flowchart is a flow chart in the parallel mode. This flowchart is a flow chart after it is determined that the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not closed and fixed.

[0096] In step S801, the control device 100 turns on the negative electrode bypass switch 50. Next, in step S802, the control device 100 turns on the precharge switch SP to obtain the voltage Vinv of the smoothing capacitor 21 and the voltage Vcb of the neutral point capacitor 90 detected by the NC voltage sensor 75. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0V, that is, when the processing in step S803 is yes, the processing proceeds to step S804.

[0097] When the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to 0V, that is, when the processing of step S804 is yes, the processing proceeds to step S807. In step S807, the control device 100 turns on the high potential side main switch SMRH to obtain the voltage Vinv of the smoothing capacitor 21. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage (400V) of the first battery 31, that is, when the processing of step S808 is yes, the processing proceeds to step S809. In step S809, the control device 100 turns on the motor side switch 60 to obtain the voltage Vcb of the neutral point capacitor 90.

[0098] When the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to the voltage (200V) of the second battery 32, that is, when the processing of step S811 is yes, the processing proceeds to step S812. In step S812, the control device 100 turns on the low potential side main switch SMRL. Then, in step S814, the control device 100 turns off the pre-charge switch SP.

[0099] Next, in step S815, the control device 100 determines whether the voltage Vinv of the smoothing capacitor 21 is greater than the voltage Vcb of the neutral point capacitor 90. The reason for making such a determination in step S815 is that when the voltage Vcb of the neutral point capacitor 90 is greater than the voltage Vinv of the smoothing capacitor 21, there is a possibility that current will flow from the neutral point capacitor 90 to the battery side via the upper arm diode DH. When the processing of step S815 is yes, the processing proceeds to step S816. When the processing of step S815 is no, the processing proceeds to step S818, and it is determined whether the phenomenon that the voltage Vcb of the neutral point capacitor 90 is greater than the voltage Vinv of the smoothing capacitor 21 is a predetermined number of times or more. When it is determined that the phenomenon that the voltage Vcb of the neutral point capacitor 90 is greater than the voltage Vinv of the smoothing capacitor 21 is a predetermined number of times or more, that is, when the processing of step S818 is yes, the processing proceeds to step S819, and the control device 100 stops charging.

[0100] In step S816, the control device 100 turns on the connection switch 80. Next, in step S817, the control device 100 starts charging.

[0101] When the processing of step S803 is No, the processing proceeds to step S805, and the control device 100 determines that the high-potential side main switch SMRH is turned on and fixed. When the processing of step S804 is No, the processing proceeds to step S806, and the control device 100 determines that the motor side switch 60 is turned on and fixed. When the processing of step S808 is No, the processing proceeds to step S810, and the control device 100 determines that the high-potential side main switch SMRH is turned off and fixed. When the processing of step S811 is No, the processing proceeds to step S813, and the control device 100 determines that the motor side switch 60 is turned off and fixed. After steps S805, S806, S810 and S813, the processing proceeds to step S819, and the control device 100 stops charging.

[0102] The result of the process of step S808 being No means that the control device 100 outputted an on command to the high potential side main switch SMRH in step S807, but the high potential side main switch SMRH was not turned on due to being disconnected and fixed. In addition, the result of the process of step S811 being No means that the control device 100 outputted an on command to the motor side switch 60 in step S809, but the motor side switch 60 was not turned on due to being disconnected and fixed.

[0103] In addition, Fig. 20 In the process of , the motor side switch 60 may be turned on before the high potential side main switch SMRH. Fig.21 The process at this time is explained. Fig.21The processing of steps S901, S902, S903, S904, S905, S906, S914, S916, S917, S918, S919, S920 and S921 is Fig. 20 The processing of steps S801, S802, S803, S804, S805, S806, S812, S814, S815, S816, S817, S818 and S819 is the same, so the description is omitted.

[0104] In step S907, the control device 100 turns on the motor side switch 60 to obtain the voltage Vinv of the neutral point capacitor 90 and the smoothing capacitor 21. When the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to the voltage (200V) of the second battery 32, that is, when the processing in step S908 is yes, the processing proceeds to step S909.

[0105] When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0V, that is, when the processing of step S909 is yes, the processing proceeds to step S911. In step S911, the control device 100 turns on the high potential side main switch SMRH to obtain the voltage Vinv of the smoothing capacitor 21. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage (400V) of the first battery 31, that is, when the processing of step S913 is yes, the processing proceeds to step S914.

[0106] When the processing of step S908 is No, the processing proceeds to step S910, and the control device 100 determines that the motor side switch 60 is OFF and fixed. When the processing of step S909 is No, the processing proceeds to step S912, and the control device 100 determines that the connection switch 80 is ON and fixed. When the processing of step S913 is No, the processing proceeds to step S915, and the control device 100 determines that the high potential side main switch SMRH is OFF and fixed.

[0107] The result of the process of step S908 being No means that in step S907, the control device 100 outputted an on command to the motor side switch 60, but the motor side switch 60 was not turned on due to being fixed in the open state. In addition, the result of the process of step S913 being No means that in step S911, the control device 100 outputted an on command to the high potential side main switch SMRH, but the high potential side main switch SMRH was not turned on due to being fixed in the open state.

[0108] Fig. 22 This is a flow chart in the series neutral point mode. This flow chart is a flow chart after determining that the inter-battery switch 40 and the inter-negative electrode bypass switch 50 are not closed and fixed.

[0109] In step S1001, the control device 100 turns on the inter-battery switch 40. Next, in step S1002, the control device 100 turns on the precharge switch SP to obtain the voltage of the smoothing capacitor 21 and the voltage Vcb of the neutral point capacitor 90. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0V, that is, when the processing in step S1003 is yes, the processing proceeds to step S1004.

[0110] When the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to 0V, that is, when the processing of step S1004 is yes, the processing proceeds to step S1007. In step S1007, the control device 100 turns on the high potential side main switch SMRH to obtain the voltage Vinv of the smoothing capacitor 21. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 600V, which is the sum of the voltages of the first battery 31 and the second battery 32, that is, when the processing of step S1008 is yes, the processing proceeds to step S1009. In step S1009, the control device 100 turns on the motor side switch 60 to obtain the voltage Vcb of the neutral point capacitor 90.

[0111] When the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to the voltage (200V) of the second battery 32, that is, when the processing of step S1011 is yes, the processing proceeds to step S1012. In step S1012, the control device 100 turns on the low potential side main switch SMRL. Then, in step S1014, the control device 100 turns off the pre-charge switch SP.

[0112] Next, in step S1015, the control device 100 determines whether the voltage Vinv of the smoothing capacitor 21 is greater than the voltage Vcb of the neutral point capacitor 90. When the processing of step S1015 is yes, the processing proceeds to step S1016. When the processing of step S1015 is no, the processing proceeds to step S1018, and it is determined whether the phenomenon that the voltage Vcb of the neutral point capacitor 90 is greater than the voltage Vinv of the smoothing capacitor 21 is a predetermined number of times or more. When it is determined that the phenomenon that the voltage Vcb of the neutral point capacitor 90 is greater than the voltage Vinv of the smoothing capacitor 21 is a predetermined number of times or more, that is, when the processing of step S1018 is yes, the processing proceeds to step S1019, and the control device 100 stops charging.

[0113] In step S1016, the control device 100 turns on the connection switch 80. Next, in step S1017, the control device 100 starts charging.

[0114] When the processing of step S1003 is No, the processing proceeds to step S1005, and the control device 100 determines that the high potential side main switch SMRH is turned on and fixed. When the processing of step S1004 is No, the processing proceeds to step S1006, and the control device 100 determines that the motor side switch 60 is turned on and fixed. When the processing of step S1008 is No, the processing proceeds to step S1010, and the control device 100 determines that the high potential side main switch SMRH is turned off and fixed. When the processing of step S1011 is No, the processing proceeds to step S1013, and the control device 100 determines that the motor side switch 60 is turned off and fixed. After steps S1005, S1006, S1010 and S1013, the processing proceeds to step S1019, and the control device 100 stops charging.

[0115] The result of the process of step S1008 being No means that the control device 100 outputted an on command to the high potential side main switch SMRH in step S1007, but the high potential side main switch SMRH was not turned on due to being disconnected and fixed. In addition, the result of the process of step S1011 being No means that the control device 100 outputted an on command to the motor side switch 60 in step S1009, but the motor side switch 60 was not turned on due to being disconnected and fixed.

[0116] In addition, Fig. 22 In the process of , the motor side switch 60 may be turned on before the high potential side main switch SMRH. Fig.23 The process at this time is explained. Fig.23 The processing of steps S1101, S1102, S1103, S1104, S1105, S1106, S1114, S1116, S1117, S1118, S1119, S1120 and S1121 is the same as Fig. 22 The processing of steps S1001, S1002, S1003, S1004, S1005, S1006, S10012, S1014, S1015, S1016, S1017, S1018 and S1019 is the same, so the description is omitted.

[0117] In step S1107, the control device 100 turns on the motor side switch 60 to obtain the voltage Vinv of the neutral point capacitor 90 and the smoothing capacitor 21. When the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to the voltage (200V) of the second battery 32, that is, when the processing in step S1108 is yes, the processing proceeds to step S1109.

[0118] When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0V, that is, when the processing of step S1109 is yes, the processing proceeds to step S1111. In step S1111, the control device 100 turns on the high potential side main switch SMRH to obtain the voltage Vinv of the smoothing capacitor 21. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the total value of the voltage of the first battery 31 and the voltage of the second battery 32, that is, 600V, that is, when the processing of step S1113 is yes, the processing proceeds to step S1114.

[0119] When the processing of step S1108 is No, the processing proceeds to step S1110, and the control device 100 determines that the motor side switch 60 is OFF and fixed. When the processing of step S1109 is No, the processing proceeds to step S1112, and the control device 100 determines that the connection switch 80 is ON and fixed. When the processing of step S1113 is No, the processing proceeds to step S1115, and the control device 100 determines that the high potential side main switch SMRH is OFF and fixed.

[0120] The result of the process of step S1108 being No means that in step S1107, the control device 100 outputted an on command to the motor side switch 60, but the motor side switch 60 was not turned on due to being disconnected and fixed. In addition, the result of the process of step S1113 being No means that in step S1111, the control device 100 outputted an on command to the high potential side main switch SMRH, but the high potential side main switch SMRH was not turned on due to being disconnected and fixed.

[0121] The control device 100 terminates the power conversion device after charging is completed. Fig.24 The shown flow ends the power conversion device. Fig.24 The process shown starts after charging is completed. In step S1201, the control device 100 performs an opening operation on each switch except the connection switch 80. Then, in step S1202, the control device 100 discharges the neutral point capacitor 90. As a method for discharging the neutral point capacitor 90, the charge of the neutral point capacitor 90 can be transferred to the smoothing capacitor 21 by boosting the voltage through the inverter 30. After the neutral point capacitor 90 is discharged until the voltage of the neutral point capacitor 90 is 0V, the process proceeds to step S1203, and the control device 100 performs an opening operation on the connection switch 80.

[0122] In step S1204, the control device 100 transfers the charge of the smoothing capacitor 21 to the neutral point capacitor 90 via the inverter 20 and the motor 10. At this time, if the connection switch 80 is not turned on and fixed, the charge of the smoothing capacitor 21 will not be transferred to the neutral point capacitor 90, and the voltage Vcb of the neutral point capacitor 90 is 0V. When the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to 0V, that is, when the processing in step S1205 is yes, the processing enters step S1206. In step S1206, the control device 100 discharges the smoothing capacitor 21 until the voltage of the smoothing capacitor 21 is 0V, and the power conversion device ends.

[0123] If the result of the process in step S1205 is NO, the process proceeds to step S1207, and the control device 100 determines that the connection switch 80 is turned on and fixed. The process proceeds to step S1208, and the control device 100 notifies the driver that an abnormality has occurred.

[0124] The result of the process in step S1205 being NO means that the control device 100 outputted an OFF command to the connection switch 80 in step S1203 , but the connection switch 80 is not in the OFF state because it is fixed in the ON state.

[0125] <Fifth embodiment> Hereinafter, referring to the accompanying drawings, the fifth embodiment will be described with a focus on the differences from the first embodiment. Fig.25 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 shown in the figure. In addition, the power conversion device includes a neutral point capacitor 91 and an NC voltage sensor 75A for detecting the voltage of the neutral point capacitor 91 between the motor side electrical path 25 and the high potential side electrical path 22H, and does not include the previous Figure 1 The neutral point capacitor 90 and the NC voltage sensor 75 are shown. In addition, the motor side electrical path 25 connects the neutral point of the armature winding 11 to a portion of the inter-battery electrical path 24 that is closer to the first battery 31 than the inter-battery switch 40. A motor side switch 61 is provided in the motor side electrical path 25. In addition, the voltage of the first battery 31 is 200V, and the voltage of the second battery 32 is 400V.

[0126] Reference Fig.26 Flow chart of the decision Fig.25The following describes an example of a method for fixing the on state of the inter-battery switch 40 or the inter-positive electrode bypass switch 51 in the circuit configuration shown. The initial state of each switch at the start time of the flowchart is a state in which an off command is received from the control device 100. In step S1301, the control device 100 selects a charging mode.

[0127] In step S1302, the control device 100 turns on the main switches SMRH and SMRL to obtain the voltage Vinv of the smoothing capacitor 21. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0V, that is, when the processing of step S1303 is yes, the processing proceeds to step S1304. In step S1304, the control device 100 determines that the inter-battery switch 40 and the inter-positive bypass switch 51 are not fixed on. The processing proceeds to step S1305, and the control device 100 switches the on and off states of each switch based on the charging mode. Thus, charging starts.

[0128] On the other hand, when the processing of step S1303 is NO, the processing proceeds to step S1306. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the total value (600V) of the voltage of the first storage battery 31 and the voltage of the second storage battery 32, that is, when the processing of step S1306 is YES, the processing proceeds to step S1307. In step S1307, the control device 100 determines that the inter-battery switch 40 is turned on and fixed. The processing proceeds to step S1308, and the control device 100 stops charging.

[0129] When the processing of step S1306 is No, the processing proceeds to step S1309. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage (400V) of the second battery 32, that is, when the processing of step S1309 is Yes, the processing proceeds to step S1310. In step S1310, the control device 100 determines that the positive electrode bypass switch 51 is turned on and fixed. Thereafter, the processing proceeds to step S1308. In addition, when the processing of step S1309 is No, the processing proceeds to step S1308 because an unexpected phenomenon may occur.

[0130] According to the fifth embodiment described in detail above, the following effects can be obtained.

[0131] The control device 100 turns on the main switches SMRH and SMRL when the power conversion device is started, that is, before charging starts, and determines whether the inter-battery switch 40 or the inter-positive electrode bypass switch 51 is turned on based on the voltage Vinv of the smoothing capacitor 21 at this time. According to this structure, it is possible to determine whether the inter-battery switch 40 or the inter-positive electrode bypass switch 51 is turned on without actually turning on or off the inter-battery switch 40 or the inter-positive electrode bypass switch 51.

[0132] <Variation 1 of the Fifth Embodiment> Regarding the inter-battery switch 40 or the inter-positive electrode bypass switch 51 being turned on and fixed, it is also possible to Fig. 27 The flowchart shown is used for determination. The flowchart is described below. The initial state of each switch at the start time of the flowchart is a state in which an opening instruction from the control device 100 is received.

[0133] In step S1401, the control device 100 selects a charging mode. In step S1402, the control device 100 turns on the low-potential side main switch SMRL, the motor side switch 61, and the connection switch 80 to obtain the voltage Vinv of the smoothing capacitor 21. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0V, that is, when the processing in step S1403 is yes, the processing enters step S1404. In step S1404, the control device 100 determines that the inter-battery switch 40 and the inter-positive bypass switch 51 are not turned on and fixed. The processing enters step S1405, and the control device 100 switches the on and off states of each switch based on the charging mode. Thus, charging starts.

[0134] On the other hand, when the processing of step S1403 is No, the processing proceeds to step S1406. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage of the second storage battery 32, that is, when the processing of step S1406 is Yes, the processing proceeds to step S1407. In step S1407, the control device 100 determines that the inter-battery switch 40 is turned on and fixed. The processing proceeds to step S1408, and the control device 100 stops charging.

[0135] When the processing of step S1406 is No, the processing proceeds to step S1409. When the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage difference between the voltage of the second storage battery 32 and the voltage of the first storage battery 31, that is, when the processing of step S1409 is Yes, the processing proceeds to step S1410. In step S1410, the control device 100 determines that the positive electrode bypass switch 51 is turned on and fixed. Thereafter, the processing proceeds to step S1408. In addition, when the processing of step S1409 is No, since an unexpected phenomenon may have occurred, the processing proceeds to step S1408.

[0136] When the inter-battery switch 40 or the inter-positive electrode bypass switch 51 is fixedly turned on, the voltage of the smoothing capacitor 21 changes. Therefore, by focusing on the voltage of the smoothing capacitor 21, it is possible to determine which of the inter-battery switch 40 and the inter-positive electrode bypass switch 51 is fixedly turned on.

[0137] ·use Figures 26-27The determination of the connection fixation described above may be performed not at the time of the start-up of the power conversion device but at the end of the power conversion device. At the end of the power conversion device, that is, after the charging is completed, each switch is controlled to be in the off state, so the connection fixation can be determined in the same way as at the start-up. However, at the end of the power conversion device, the charge is accumulated in the smoothing capacitor 21 due to the charging. Therefore, in order to determine the connection fixation at the end of the power conversion device, it is necessary to discharge the smoothing capacitor 21 so that the voltage of the smoothing capacitor 21 is 0V. The method of discharging the smoothing capacitor 21 is the same as the modification of the first embodiment.

[0138] <Sixth embodiment> Hereinafter, with reference to the accompanying drawings, the sixth embodiment will be described with a focus on the differences from the fifth embodiment. Fig.28 As shown, the power conversion device includes at least any one of the following: an inter-battery switch voltage sensor 86 for detecting the voltage across the inter-battery switch 40; a bypass switch voltage sensor 87 for detecting the voltage across the positive bypass switch 51; an inter-terminal voltage sensor 88 for detecting the voltage between the negative terminal of the first battery 31 and the negative terminal of the second battery 32, that is, the terminal voltage; and a PN voltage sensor 89 for detecting the voltage between the high potential side electrical path 22H and the low potential side electrical path 22L, that is, the PN voltage.

[0139] The control device 100 determines whether the inter-battery switch 40 or the positive electrode bypass switch 51 is fixed on based on any one of the voltages across the inter-battery switch voltage sensor 86, the voltage across the inter-battery switch voltage sensor 87, the terminal voltage detected by the terminal voltage sensor 88, and the PN voltage detected by the PN voltage sensor 89.

[0140] First, refer to Fig.29 , the method for determining the voltage across the inter-battery switch 40 is described first using the flowchart. In step S1501, the control device 100 determines whether the voltage across the inter-battery switch 40 detected by the inter-battery switch voltage sensor 86 is the total value of the voltage of the first storage battery 31 and the voltage of the second storage battery 32, that is, 600V. In the present embodiment, when the inter-battery switch 40 and the inter-positive electrode bypass switch 51 are not fixedly connected and are in the open state, the voltage across the inter-battery switch 40 VB2 becomes the total value of the voltage of the first storage battery 31 and the voltage of the second storage battery 32, that is, 600V. Therefore, when the processing of step S1501 is yes, the processing proceeds to step S1502, and the control device 100 determines that the inter-battery switch 40 and the inter-positive electrode bypass switch 51 are not fixedly connected.

[0141] On the other hand, when the processing of step S1501 is No, the processing proceeds to step S1503. In step S1503, the control device 100 determines whether the voltage VB2 across the inter-battery switch 40 is 0 V. In the present embodiment, when the inter-battery switch 40 is turned on and fixed, the voltage VB2 across the inter-battery switch 40 is 0 V. Therefore, when the processing of step S1503 is Yes, the processing proceeds to step S1504, and the control device 100 determines that the inter-battery switch 40 is turned on and fixed.

[0142] When the processing of step S1503 is No, the processing proceeds to step S1505. In step S1505, the control device 100 determines whether the voltage VB2 across the inter-battery switch 40 is equal to the voltage (200V) of the first storage battery 31. In the present embodiment, when the inter-positive electrode bypass switch 51 is turned on and fixed, the voltage VB2 across the inter-battery switch 40 is equal to the voltage of the first storage battery 31. Therefore, when the processing of step S1505 is Yes, the processing proceeds to step S1506, and the control device 100 determines that the inter-positive electrode bypass switch 51 is turned on and fixed.

[0143] After steps S1504 and S1506, the process proceeds to step S1507, and the control device 100 stops charging. Also, when the result of the process in step S1505 is NO, the process proceeds to step S1507.

[0144] Next, refer to Fig.30 , a method for determining the voltage across the positive electrode bypass switch 51 is described using a flowchart. In step S1601, the control device 100 determines whether the voltage across the positive electrode bypass switch 51 detected by the bypass switch voltage sensor 87 is equal to the voltage (400V) of the second storage battery 32. In the present embodiment, when the inter-battery switch 40 and the inter-positive electrode bypass switch 51 are not fixedly connected and are in an open state, the voltage across the positive electrode bypass switch 51 VP2 is equal to the voltage of the second storage battery 32. Therefore, when the processing of step S1601 is yes, the processing proceeds to step S1602, and the control device 100 determines that the inter-battery switch 40 and the inter-positive electrode bypass switch 51 are not fixedly connected.

[0145] On the other hand, when the processing of step S1601 is NO, the processing proceeds to step S1603. In step S1603, the control device 100 determines whether the voltage VP2 across the positive electrode bypass switch 51 is equal to the voltage (200V) of the first storage battery 31. In the present embodiment, when the inter-battery switch 40 is turned on and fixed, the voltage VP2 across the positive electrode bypass switch 51 is equal to the voltage of the first storage battery 31. Therefore, when the processing of step S1603 is YES, the processing proceeds to step S1604, and the control device 100 determines that the inter-battery switch 40 is turned on and fixed.

[0146] When the processing of step S1603 is No, the processing proceeds to step S1605. In step S1605, the control device 100 determines whether the voltage VP2 across the positive electrode bypass switch 51 is 0 V. In the present embodiment, when the positive electrode bypass switch 51 is fixedly turned on, the voltage VP2 across the positive electrode bypass switch 51 is 0 V. Therefore, when the processing of step S1605 is Yes, the processing proceeds to step S1606, and the control device 100 determines that the positive electrode bypass switch 51 is fixedly turned on.

[0147] After steps S1604 and S1606, the process proceeds to step S1607, and the control device 100 stops charging. Also, when the result of the process in step S1605 is NO, the process proceeds to step S1607.

[0148] Next, refer to Fig.31 , the determination method using the terminal voltage is described. In step S1701, the control device 100 determines whether the terminal voltage VT2 detected by the terminal voltage sensor 88 is equal to the voltage of the first storage battery 31. In the present embodiment, when the inter-battery switch 40 and the positive electrode bypass switch 51 are not fixedly connected and are in the disconnected state, the terminal voltage VT2 is equal to the voltage of the first storage battery 31. Therefore, when the processing of step S1701 is yes, the processing enters step S1702, and the control device 100 determines that the inter-battery switch 40 and the positive electrode bypass switch 51 are not fixedly connected.

[0149] On the other hand, when the processing of step S1701 is NO, the processing proceeds to step S1703. In step S1703, the control device 100 determines whether the inter-terminal voltage VT2 is equal to the voltage of the second storage battery 32. In the present embodiment, when the inter-battery switch 40 is turned on and fixed, the inter-terminal voltage VT2 is equal to the voltage of the second storage battery 32. Therefore, when the processing of step S1703 is YES, the processing proceeds to step S1704, and the control device 100 determines that the inter-battery switch 40 is turned on and fixed.

[0150] When the processing of step S1703 is No, the processing proceeds to step S1705. In step S1705, the control device 100 determines whether the inter-terminal voltage VT2 is equal to the voltage difference between the voltage of the second storage battery 32 and the voltage of the first storage battery 31. In the present embodiment, when the inter-positive electrode bypass switch 51 is fixedly turned on, the inter-terminal voltage VT2 is equal to the voltage difference between the voltage of the first storage battery 31 and the voltage of the second storage battery 32. Therefore, when the processing of step S1705 is Yes, the processing proceeds to step S1706, and the control device 100 determines that the inter-positive electrode bypass switch 51 is fixedly turned on.

[0151] After steps S1704 and S1706, the process proceeds to step S1707, and the control device 100 stops charging. Also, when the result of the process in step S1705 is NO, the process proceeds to step S1707.

[0152] Next, refer to Fig.32 , the determination method using the PN voltage is described. In step S1801, the control device 100 determines whether the PN voltage VPN2 detected by the PN voltage sensor 89 is 0V. In the present embodiment, when the inter-battery switch 40 and the inter-positive electrode bypass switch 51 are not fixedly turned on and become disconnected, the PN voltage VPN2 becomes 0V. Therefore, when the processing of step S1801 is yes, the processing proceeds to step S1802, and the control device 100 determines that the inter-battery switch 40 and the inter-positive electrode bypass switch 51 are not fixedly turned on.

[0153] On the other hand, when the processing of step S1801 is NO, the processing proceeds to step S1803. In step S1803, the control device 100 determines whether the PN voltage VPN2 is the sum of the voltage of the first storage battery 31 and the voltage of the second storage battery 32, that is, 600 V. In the present embodiment, when the inter-battery switch 40 is turned on and fixed, the PN voltage VPN2 is the sum of the voltage of the first storage battery 31 and the voltage of the second storage battery 32, that is, 600 V. Therefore, when the processing of step S1803 is YES, the processing proceeds to step S1804, and the control device 100 determines that the inter-battery switch 40 is turned on and fixed.

[0154] When the processing of step S1803 is No, the processing proceeds to step S1805. In step S1805, the control device 100 determines whether the PN voltage VPN2 is equal to the voltage (400V) of the second storage battery 32. In the present embodiment, when the positive electrode bypass switch 51 is fixedly turned on, the PN voltage VPN2 is equal to the voltage of the second storage battery 32. Therefore, when the processing of step S1805 is Yes, the processing proceeds to step S1806, and the control device 100 determines that the positive electrode bypass switch 51 is fixedly turned on.

[0155] After steps S1804 and S1806, the process proceeds to step S1807, and the control device 100 stops charging. Also, when the result of the process in step S1805 is NO, the process proceeds to step S1807.

[0156] According to the sixth embodiment described in detail above, the following effects can be obtained.

[0157] When the power conversion device is started, that is, before charging starts, the control device 100 uses any one of the voltages detected by the voltage sensors 86 to 89 to determine whether the inter-battery switch 40 or the inter-positive electrode bypass switch 51 is fixedly closed. According to this configuration, it is possible to determine whether the inter-battery switch 40 or the inter-positive electrode bypass switch 51 is fixedly closed without actually performing an on-operation or an off-operation on the inter-battery switch 40 or the inter-positive electrode bypass switch 51.

[0158] When the inter-battery switch 40 or the inter-positive electrode bypass switch 51 is fixedly turned on, the voltage detected by each voltage sensor 86 to 89 changes. Therefore, by focusing on any one of the voltages detected by each voltage sensor 86 to 89, it is possible to determine which of the inter-battery switch 40 and the inter-positive electrode bypass switch 51 is fixedly turned on.

[0159] <Modification of Sixth Embodiment> ·use Figures 29 to 32 The above-described determination of the on-fixing state may be performed not when the power conversion device is started but when the power conversion device is stopped. When the power conversion device is stopped, that is, after charging is completed, each switch is controlled to an off state, so the on-fixing state can be determined in the same way as when starting.

[0160] <Seventh embodiment> Hereinafter, referring to the accompanying drawings, the seventh embodiment will be described with a focus on the differences from the first embodiment. Fig.33 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.

[0161] The control device 100, for example, can charge the second battery 32 alone through the low-voltage charger 200 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.

[0162] <Eighth Embodiment> Hereinafter, referring to the accompanying drawings, the eighth embodiment will be described with a focus on the differences from the fifth embodiment. Fig.34 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.

[0163] The control device 100, for example, is capable of charging the first battery 31 alone through the low-voltage charger 200 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.

[0164] <Ninth embodiment> Hereinafter, referring to the accompanying drawings, the ninth embodiment will be described with a focus on the differences from the above-mentioned embodiments. Fig.35 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 .

[0165] The neutral point of the armature winding 11 is connected to a first end of a common path 26. A second end of the common path 26 is connected to a first end of a first electrical path 27, and a second end of the first electrical path 27 is connected to a position of the inter-battery electrical path 24 that is closer to the second battery 32 than the inter-battery switch 40. In addition, a second end of the common path 26 is connected to a first end of a second electrical path 28, and a second end of the second electrical path 28 is connected to a position of 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.

[0166] According to the present embodiment described above, it is possible to Figure 1 The circuit structure shown in Fig. 9 Processing and Fig.13 processing.

[0167] <Tenth embodiment> Hereinafter, referring to the accompanying drawings, the tenth embodiment will be described with a focus on the differences from the above-mentioned embodiments. Fig.36 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 .

[0168] The neutral point of the armature winding 11 is connected to a first end of a common path 26. A second end of the common path 26 is connected to a first end of a first electrical path 27, and a second end of the first electrical path 27 is connected to a position of the inter-battery electrical path 24 that is closer to the second battery 32 than the inter-battery switch 40. In addition, a second end of the common path 26 is connected to a first end of a second electrical path 28, and a second end of the second electrical path 28 is connected to a position of 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.

[0169] According to the present embodiment described above, it is possible to Fig.25 The circuit structure shown in Fig.26 Processing and Fig. 27 processing.

[0170] <Other embodiments> In addition, each of the above-mentioned embodiments may be implemented with the following modifications.

[0171] The electric motor is not limited to a star-connected electric motor, but may be a delta-connected electric motor. In addition, the electric motor and inverter are not limited to a three-phase electric motor, but may be a two-phase electric motor or a four-phase or more electric motor. In addition, the electric motor is not limited to a permanent magnet type synchronous machine having a permanent magnet as an excitation pole in the rotor, but may be a winding excitation type synchronous machine having an excitation coil as an excitation pole in the rotor. In this case, both the excitation winding and the permanent magnet may be included in the rotor. In addition, the electric motor is not limited to a synchronous machine, but may be an induction machine.

[0172] 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 terminal of the N-channel MOSFET is the drain, and the low potential terminal is the source.

[0173] The power storage unit to be charged by the external charger is not limited to a battery, and may be, for example, a large-capacity electric double layer capacitor, or may include both a battery and an electric double layer capacitor.

[0174] The installation location of the power conversion device is not limited to a mobile object, and a stationary device may be used.

[0175] ·The control unit and the method thereof 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 the method thereof 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 the method thereof 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.

[0176] 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: a high potential side electrical path (22H) capable of being electrically connected to the positive terminal of the first power storage unit (31); a low potential side electrical path (22L) capable of being electrically connected to a negative terminal of a second power storage unit (32); an inverter (20) having an upper arm switch (SWH) electrically connected to the high potential side electrical path and a lower arm switch (SWL) electrically connected to the low potential side electrical path; and an electric motor (10) electrically connected to a connection point between the upper arm switch and the lower arm switch, The power conversion device 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 bypass switch (50, 51) for performing at least one of an electrical connection between the negative terminals of the first power storage unit and the second power storage unit and an electrical connection between the positive terminals of the first power storage unit and the second power storage unit; and A control unit (100) determines whether or not the switch between the power storage units and the bypass switch is fixedly turned on before turning on the other switch.

2. The power conversion device according to claim 1, characterized in that: include: a smoothing capacitor (21) which electrically connects the high potential side electrical path and the low potential side electrical path and smoothes the input voltage of the inverter; a voltage sensor (19) for detecting a voltage of the smoothing capacitor; 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 control unit determines whether one of the switch between power storage units and the bypass switch is fixedly turned on based on the voltage of the smoothing capacitor detected by the voltage sensor when the high potential side switch and the low potential side switch are turned on.

3. The power conversion device according to claim 2, characterized in that: The bypass switch is an inter-negative electrode bypass switch (50) that electrically connects the negative terminal of the first power storage unit and the negative terminal of the second power storage unit. When the control unit determines that the voltage of the smoothing capacitor is equal to 0 V, the control unit determines that the switch between the power storage units and the bypass switch between the negative electrodes are not fixedly closed. When it is determined that the voltage of the smoothing capacitor is equal to the sum of the voltage of the first power storage unit and the voltage of the second power storage unit, it is determined that the switch between power storage units is fixedly turned on, When it is determined that the voltage of the smoothing capacitor is equal to the voltage of the first power storage unit, it is determined that the negative electrode bypass switch is fixedly turned on.

4. The power conversion device according to claim 1, characterized in that: The electric motor has an armature winding (11), The first end side of the armature winding is electrically connected to the connection point of the upper arm switch and the lower arm switch. The power conversion device further comprises: a smoothing capacitor (21) which electrically connects the high potential side electrical path and the low potential side electrical path and smoothes the input voltage of the inverter; a voltage sensor (19) for detecting a voltage of the smoothing capacitor; 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; a motor-side electrical path (25) electrically connecting the second end side of the armature winding and the electrical path between the power storage units; a motor-side switch (60) disposed in the motor-side electrical path; and a connecting switch (80) provided in the motor-side electrical path at a position closer to the connecting point than the motor-side switch, The control unit determines whether one of the switch between power storage units and the bypass switch is fixedly turned on based on the voltage of the smoothing capacitor detected by the voltage sensor when the high potential side switch, the motor side switch, and the connection switch are turned on.

5. The power conversion device according to claim 4, characterized in that: The bypass switch is an inter-negative electrode bypass switch (50) that electrically connects the negative terminal of the first power storage unit and the negative terminal of the second power storage unit. The motor-side electrical path is a path that electrically connects the second end side of the armature winding and a portion of the inter-storage unit electrical path that is closer to the second storage unit than the inter-storage unit switch. When the control unit determines that the voltage of the smoothing capacitor is equal to 0 V, the control unit determines that the switch between the power storage units and the bypass switch between the negative electrodes are not fixedly closed. When it is determined that the voltage of the smoothing capacitor is equal to the voltage of the first power storage unit, it is determined that the switch between power storage units is fixedly turned on, When it is determined that the voltage of the smoothing 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, it is determined that the negative electrode bypass switch is fixedly turned on.

6. The power conversion device according to claim 1, characterized in that: The bypass switch is an inter-negative electrode bypass switch (50) that electrically connects the negative terminal of the first power storage unit and the negative terminal of the second power storage unit. The control unit determines whether either the switch between the storage units or the bypass switch between the negative electrodes is turned on and fixed based on at least one of the voltage across the switch between the storage units, the voltage across the bypass switch between the negative electrodes, the voltage between the high potential side electrical path and the low potential side electrical path, or the voltage between the positive terminal of the first storage unit and the positive terminal of the second storage unit.

7. The power conversion device according to claim 6, characterized in that: The control unit determines that the switch between storage units and the negative electrode bypass switch are not fixedly closed when it is determined that the voltage across the switch between storage units is equal to the sum of the voltage of the first storage unit and the voltage of the second storage unit. When it is determined that the voltage across the switch between the power storage units is equal to 0 V, it is determined that the switch between the power storage units is fixedly turned on, When it is determined that the voltage across the switch between power storage units is equal to the voltage of the second power storage unit, it is determined that the bypass switch between negative electrodes is fixedly turned on.

8. The power conversion device according to claim 6, characterized in that: The control unit determines that the switch between storage units and the bypass switch between negative electrodes are not fixedly closed when it is determined that the voltage across the bypass switch between negative electrodes is equal to the voltage of the first storage unit. When it is determined that the voltage across the inter-negative electrode bypass switch is equal to the voltage of the second power storage unit, it is determined that the switch between power storage units is turned on and fixed. When it is determined that the voltage across the inter-negative electrode bypass switch is equal to 0 V, it is determined that the inter-negative electrode bypass switch is turned on and fixed.

9. The power conversion device according to claim 6, characterized in that: The control unit determines that the switch between the power storage units and the bypass switch between the negative electrodes are not fixedly closed when it is determined that the voltage between the high potential side electrical path and the low potential side electrical path is equal to 0 V. When it is determined that the voltage between the high potential side electrical path and the low potential side electrical path is equal to the sum of the voltage of the first storage unit and the voltage of the second storage unit, it is determined that the switch between the storage units is fixedly turned on, When it is determined that the voltage between the high potential side electrical path and the low potential side electrical path is equal to the voltage of the first power storage unit, it is determined that the negative electrode bypass switch is fixedly closed.

10. The power conversion device according to claim 6, characterized in that: The control unit determines that the switch between the storage units and the bypass switch between the negative electrodes are not fixedly closed when it is determined that the voltage between the positive terminal of the first storage unit and the positive terminal of the second storage unit is equal to the voltage of the second storage unit. When it is determined that the voltage between the positive terminal of the first power storage unit and the positive terminal of the second power storage unit is equal to the voltage of the first power storage unit, it is determined that the switch between the power storage units is fixedly turned on, When it is determined that the voltage between the positive terminal of the first power storage unit and the positive terminal of the second power storage unit is equal to the voltage difference between the voltage of the first power storage unit and the voltage of the second power storage unit, it is determined that the inter-negative electrode bypass switch is fixedly closed.

11. The power conversion device according to claim 2, characterized in that: The bypass switch is a positive electrode bypass switch (51) that electrically connects the positive electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit. When the control unit determines that the voltage of the smoothing capacitor is equal to 0 V, the control unit determines that the switch between the storage units and the bypass switch between the positive electrodes are not fixedly closed. When it is determined that the voltage of the smoothing capacitor is equal to the sum of the voltage of the first power storage unit and the voltage of the second power storage unit, it is determined that the switch between power storage units is fixedly turned on, When it is determined that the voltage of the smoothing capacitor is equal to the voltage of the second power storage unit, it is determined that the positive electrode bypass switch is fixedly turned on.

12. The power conversion device according to claim 1, characterized in that: The electric motor has an armature winding (11), The first end side of the armature winding is electrically connected to the connection point of the upper arm switch and the lower arm switch. The power conversion device further comprises: a smoothing capacitor (21) which electrically connects the high potential side electrical path and the low potential side electrical path and smoothes the input voltage of the inverter; a voltage sensor (19) for detecting a voltage of the smoothing capacitor; 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; a motor-side electrical path (25) electrically connecting the second end side of the armature winding and the electrical path between the power storage units; a motor-side switch (61) disposed in the motor-side electrical path; and a connecting switch (80) provided in the motor-side electrical path at a position closer to the connecting point than the motor-side switch, The control unit determines whether one of the switch between power storage units and the bypass switch is fixedly turned on based on the voltage of the smoothing capacitor detected by the voltage sensor when the low potential side switch, the motor side switch, and the connection switch are turned on.

13. The power conversion device according to claim 12, characterized in that: The bypass switch is a positive electrode bypass switch (51) that electrically connects the positive electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit. The motor-side electrical path is a path that electrically connects the second end side of the armature winding and a portion of the inter-storage unit electrical path that is closer to the first storage unit than the inter-storage unit switch. When the control unit determines that the voltage of the smoothing capacitor is equal to 0 V, the control unit determines that the switch between the storage units and the bypass switch between the positive electrodes are not fixedly closed. When it is determined that the voltage of the smoothing capacitor is equal to the voltage of the second power storage unit, it is determined that the switch between power storage units is fixedly turned on, When it is determined that the voltage of the smoothing capacitor is equal to the voltage difference between the voltage of the second power storage unit and the voltage of the first power storage unit, it is determined that the positive electrode bypass switch is fixedly turned on.

14. The power conversion device according to claim 1, characterized in that: The bypass switch is a positive electrode bypass switch (51) that electrically connects the positive electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit. The control unit determines whether either the switch between the storage units or the bypass switch between the positive electrodes is turned on and fixed based on at least one of the voltage across the switch between the storage units, the voltage across the bypass switch between the positive electrodes, the voltage between the high potential side electrical path and the low potential side electrical path, or the voltage between the negative terminal of the first storage unit and the negative terminal of the second storage unit.

15. The power conversion device according to claim 14, characterized in that: The control unit determines that the switch between storage units and the positive electrode bypass switch are not fixedly closed when it is determined that the voltage across the switch between storage units is equal to the sum of the voltage of the first storage unit and the voltage of the second storage unit. When it is determined that the voltage across the switch between the power storage units is equal to 0 V, it is determined that the switch between the power storage units is fixedly turned on, When it is determined that the voltage across the switch between power storage units is equal to the voltage of the first power storage unit, it is determined that the bypass switch between positive electrodes is fixedly turned on.

16. The power conversion device according to claim 14, characterized in that: The control unit determines that the switch between storage units and the bypass switch between positive electrodes are not fixedly closed when it is determined that the voltage across the bypass switch between positive electrodes is equal to the voltage of the second storage unit. When it is determined that the voltage across the positive electrode bypass switch is equal to the voltage of the first power storage unit, it is determined that the switch between power storage units is turned on and fixed. When it is determined that the voltage across the positive electrode bypass switch is equal to 0 V, it is determined that the positive electrode bypass switch is turned on and fixed.

17. The power conversion device according to claim 14, characterized in that: The control unit determines that the switch between the storage units and the bypass switch between the positive electrodes are not fixedly closed when it is determined that the voltage between the high potential side electrical path and the low potential side electrical path is equal to 0 V. When it is determined that the voltage between the high potential side electrical path and the low potential side electrical path is equal to the sum of the voltage of the first storage unit and the voltage of the second storage unit, it is determined that the switch between the storage units is fixedly turned on, When it is determined that the voltage between the high potential side electrical path and the low potential side electrical path is equal to the voltage of the second power storage unit, it is determined that the positive electrode bypass switch is fixedly closed.

18. The power conversion device according to claim 14, characterized in that: The control unit determines that the switch between the storage units and the bypass switch between the positive electrodes are not fixedly closed when it is determined that the voltage between the negative terminal of the first storage unit and the negative terminal of the second storage unit is equal to the voltage of the first storage unit. When it is determined that the voltage between the negative terminal of the first power storage unit and the negative terminal of the second power storage unit is equal to the voltage of the second power storage unit, it is determined that the switch between the power storage units is fixedly turned on, When it is determined that the voltage between the negative terminal of the first power storage unit and the negative terminal of the second power storage unit is equal to the voltage difference between the voltage of the second power storage unit and the voltage of the first power storage unit, it is determined that the positive electrode bypass switch is fixedly closed.

19. A program for a power conversion device, the power conversion device comprising: a high potential side electrical path (22H) capable of being electrically connected to the positive terminal of the first power storage unit (31); a low potential side electrical path (22L) capable of being electrically connected to a negative terminal of a second power storage unit (32); An inverter (20) having an upper arm switch (SWH) electrically connected to the high potential side electrical path and a lower arm switch (SWL) electrically connected to the low potential side electrical path; an electric motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; as well as Computer (101), The power conversion device comprises: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) electrically connecting a negative terminal of the first storage unit and a positive terminal of the second storage unit; and a bypass switch (50, 51) for performing at least one of an electrical connection between the negative terminals of the first power storage unit and the second power storage unit and an electrical connection between the positive terminals of the first power storage unit and the second power storage unit, The program causes the computer to execute the following processing: Before turning on either the switch between the power storage units or the bypass switch, it is determined whether the other switch is fixedly turned on.

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