Electric power conversion device and program

Abstract

This power conversion device comprises: a high potential-side electric path (22H) electrically connectable to a positive electrode terminal of a first power storage unit (31); a low potential-side electric path (22L) electrically connectable to a negative electrode terminal of a second power storage unit (32); an inverter (20); and a motor (10). The power conversion device comprises: an inter-power-storage-unit switch (40) provided on an inter-power-storage-unit electric path (24) electrically connecting a negative electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit; a bypass switch (50, 51) that carries out electrical connection of at least one of electrical connection between the negative electrode terminals of the first power storage unit and the second power storage unit, and electrical connection between the positive electrode terminals of the first power storage unit and the second power storage unit; and a control unit (100) that determines whether, prior to making an ON operation of one of the inter-power-storage-unit switch and the bypass switch, the other is stuck in the ON position.

Description

Power conversion device and program CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2022-144021, filed on September 9, 2022, the contents of which are incorporated herein by reference.

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

[0003] Conventionally, there is known a control device that determines whether a switch in a power conversion device is stuck on when charging an on-board battery using an external charger. For example, a control device described in Patent Document 1 transmits an ON command to the switch to be determined and checks the voltage across the switch. At this time, if the voltage across the switch is the same, the control device determines that the switch is stuck on.

[0004] U.S. Pat. No. 1,124,5346

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

[0006] The present disclosure has been made in view of the above-described problems, and aims to provide a power conversion device and a program that can suppress the flow of short-circuit current between switches.

[0007] The present disclosure provides a power conversion device including: a high-potential side electrical path electrically connectable to a positive terminal of a first power storage unit; a low-potential side electrical path electrically connectable to a negative terminal of a second power storage unit; an inverter having 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 of the upper arm switch and the lower arm switch, an inter-storage unit switch provided in the inter-storage unit electrical path electrically connecting the negative terminal of the first power storage unit and the positive terminal of the second power storage unit; a bypass switch that makes 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 that determines whether or not one of the inter-storage unit switch and the bypass switch is stuck on before turning on the other switch.

[0008] According to the above configuration, when it is determined that one switch is stuck on, the other switch is not turned on, thereby preventing a short-circuit current from flowing between the switches.

[0009] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. 1 is an overall configuration diagram of a system according to a first embodiment, FIG. 2 is a diagram showing an operation mode of a switch during low-voltage charging, FIG. 3 is a diagram showing an operation mode of a switch during high-voltage charging, FIG. 4 is a diagram showing an operation mode of a switch during high-voltage charging, FIG. 5 is a diagram explaining a mechanism by which a short-circuit current occurs, FIG. 6 is a diagram explaining a method for determining a stuck-on state using a smoothing capacitor according to the first embodiment, FIG. 7 is a diagram explaining a method for determining a stuck-on state using a smoothing capacitor according to the first embodiment, FIG. 8 is a diagram explaining a method for determining a stuck-on state using a smoothing capacitor according to the first embodiment, FIG. 9 is a flowchart explaining an example of an operation of a control device according to the first embodiment, FIG. 10 is a diagram explaining a method for determining a stuck-on state using a smoothing capacitor according to a second embodiment, FIG. 11 is a diagram explaining a method for determining a stuck-on state using a smoothing capacitor according to the second embodiment, FIG. 12 is a diagram explaining a method for determining a stuck-on state using a smoothing capacitor according to the second embodiment, and FIG. 14 is a flowchart illustrating an example of operation of the control device according to the embodiment, FIG. 15 is a flowchart illustrating an example of operation of the control device according to the third embodiment, FIG. 16 is a flowchart illustrating an example of operation of the control device according to the third embodiment, FIG. 17 is a flowchart illustrating an example of operation of the control device according to the third embodiment, FIG. 18 is a flowchart illustrating an example of operation of the control device according to the third embodiment, FIG. 19 is a flowchart illustrating an example of operation of the control device according to the fourth embodiment, FIG. 20 is a flowchart illustrating an example of operation of the control device according to the fourth embodiment, FIG. 21 is a flowchart illustrating an example of operation of the control device according to the fourth embodiment, FIG. 22 is a flowchart illustrating an example of operation of the control device according to the fourth embodiment, FIG. 23 is a flowchart illustrating an example of operation of the control device according to the fourth embodiment, FIG. 24 is a flowchart illustrating an example of operation of the control device according to the fourth embodiment, and FIG.FIG. 26 is a diagram illustrating an overall configuration of a system according to the fifth embodiment, FIG. 27 is a flowchart illustrating an example of operation of a control device according to a modification of the fifth embodiment, FIG. 28 is a diagram illustrating an overall configuration of a system according to the sixth embodiment, FIG. 29 is a flowchart illustrating an example of operation of a control device according to the sixth embodiment, FIG. 30 is a flowchart illustrating an example of operation of a control device according to the sixth embodiment, FIG. 31 is a flowchart illustrating an example of operation of a control device according to the sixth embodiment, FIG. 32 is a flowchart illustrating an example of operation of a control device according to the sixth embodiment, FIG. 33 is a diagram illustrating an overall configuration of a system according to the seventh embodiment, FIG. 34 is a diagram illustrating an overall configuration of a system according to the eighth embodiment, FIG. 35 is a diagram illustrating an overall configuration of a system according to the ninth embodiment, and FIG. 36 is a diagram illustrating an overall configuration of a system according to the tenth embodiment.

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

[0011] A first embodiment of a power conversion device according to the present disclosure will now be described with reference to the drawings. The power conversion device of this embodiment is installed in an electric vehicle such as an electric car or a hybrid car, an electric aircraft, an electric ship, or the like, and forms an electric mobile body system.

[0012] The system includes a power conversion device. As shown in FIG. 1, the power conversion device includes a motor 10, an inverter 20, a high-potential side electrical path 22H, and a low-potential side electrical path 22L. The motor 10 is a three-phase synchronous machine and includes star-connected armature windings 11 of U, V, and W phases, and a rotor (not shown). The armature windings 11 of each phase are arranged with an electrical angle offset of 120°. The motor 10 is, for example, a permanent magnet synchronous machine. The rotor is capable of transmitting power to the drive wheels of the vehicle. Therefore, the motor 10 serves as a source of torque for propelling the vehicle.

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

[0014] The inverter 20 includes a smoothing capacitor 21. A first end of a long high-potential electrical path 22H is connected to a high-potential terminal of the smoothing capacitor 21. A first end of a long low-potential electrical path 22L is connected to a low-potential terminal of the smoothing capacitor 21. The smoothing capacitor 21 may be provided outside the inverter 20. The voltage of the smoothing capacitor 21 is detected by an SC voltage sensor 19.

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

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

[0017] The system includes a first storage battery 31 (corresponding to the "first power storage unit") and a second storage battery 32 (corresponding to the "second power storage unit"). Each storage battery 31, 32 serves as a power supply source for rotating the rotor of the motor 10. Each storage battery 31, 32 is a battery pack configured as a series connection of battery cells, which are single cells. A positive terminal of the first storage battery 31 is connected to a high-potential side electrical path 22H, and a negative terminal of the second storage battery 32 is connected to a low-potential side electrical path 22L. In this embodiment, the terminal voltage (e.g., rated voltage) of the first storage battery 31 is 400 V, and the terminal voltage (e.g., rated voltage) of the second storage battery 32 is 200 V. However, this is not limited thereto, and the terminal voltage of the first storage battery 31 need only be equal to or higher than the terminal voltage of the second storage battery 32. The battery cells are, for example, secondary batteries such as lithium-ion batteries.

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

[0019] The power conversion device includes a main switch for electrically connecting or disconnecting the first and second storage batteries 31, 32 from the inverter 20. Specifically, the main switches include a high-side main switch SMRH and a low-side main switch SMRL. The power conversion device also includes a charging switch for electrically connecting or disconnecting the first and second storage batteries 31, 32 from an external charger. Specifically, the charging switches include a high-side charging switch DCRH and a low-side charging switch DCRL. In this embodiment, the switches SMRH, SMRL, DCRH, and DCRL are described as mechanical relays, but are not limited thereto and may be semiconductor switching elements. The switches SMRH, SMRL, DCRH, and DCRL block bidirectional current flow in an OFF state and allow bidirectional current flow in an ON state. The high-side electrical path 22H includes, in order from the inverter 20 side, the high-side main switch SMRH and the high-side charging switch DCRH. The low potential side electrical path 22L is provided with a low potential side main switch SMRL and a low potential side charging switch DCRL in this order from the inverter 20 side.

[0020] The power conversion device includes an inter-battery switch 40, 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 either a series connection state or a parallel connection state with an external charger. In this 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 be semiconductor switching elements. The inter-battery switch 40, the inter-negative electrode bypass switch 50, the motor-side switch 60, and the connection switch 80 block bidirectional current flow in the off state and allow bidirectional current flow in the on state.

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

[0023] The motor-side switch 60 and the connection switch 80 are provided in a motor-side electrical path 25 that connects the portion of the inter-battery electrical path 24 closer to the second storage battery 32 than the inter-battery switch 40 and the neutral point of the armature winding 11. More specifically, the connection switch 80 is provided in the motor-side electrical path 25 closer to the neutral point than the motor-side switch 60. When the motor-side switch 60 and the connection switch 80 are in an ON state, the neutral point of the armature winding 11 and the positive terminal of the second storage battery 32 are electrically connected. On the other hand, when the motor-side switch 60 and the connection switch 80 are in an OFF state, the neutral point of the armature winding 11 and the positive terminal of the second storage battery 32 are electrically disconnected. The motor-side electrical path 25 electrically connects the neutral point of the armature winding 11 and a portion of the inter-battery electrical path 24 closer to the second storage battery 32 than the inter-battery switch 40.

[0024] The power conversion device includes a first voltage sensor 71 that detects the terminal voltage of the first storage battery 31 and a second voltage sensor 72 that detects the terminal voltage of the second storage battery 32. The power conversion device also includes a first current sensor 73 that detects the current flowing through the first storage battery 31 and a second current sensor 74 that detects the current flowing through the second storage battery 32. The first current sensor 73 is provided on an electrical path connecting the positive terminal of the first storage battery 31 and the high-potential side electrical path 22H. The second current sensor 74 is provided on an electrical path connecting the negative terminal of the second storage battery 32 and the low-potential side electrical path 22L. The power conversion device also includes, as other sensors, a rotation angle sensor that detects the rotation angle (electrical angle) of the rotor and phase current sensors that detect phase currents flowing through the armature windings 11 of each phase.

[0025] The detected values ​​of each sensor are input to a control device 100 (corresponding to a "controller") included in the power conversion device. The control device 100 is mainly configured with a microcomputer 101, which includes a CPU. The functions provided by the microcomputer 101 can be provided by software recorded in a physical memory device and a computer executing the software, software alone, hardware alone, or a combination thereof. For example, if the microcomputer 101 is provided by a hardware electronic circuit, the functions can be provided by a digital circuit including multiple logic circuits or an analog circuit. For example, the microcomputer 101 executes a program stored in a non-transitory tangible storage medium serving as a memory unit included in the microcomputer 101. The program includes, for example, a program for a process shown in FIG. 9 (described later). Execution of the program results in the execution of a method corresponding to the program. The memory unit is, for example, a non-volatile memory. The program stored in the memory unit can be updated via a communication network such as the Internet, for example, via OTA (Over the Air).

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

[0027] The positive electrode connection portion of the high-potential side electrical path 22H and the negative electrode connection portion of the low-potential side electrical path 22L are interfaces for connection to an external charger. In this embodiment, the external charger is a low-voltage charger 200 or a high-voltage charger 210 (see FIGS. 2 to 4). The charging voltage of the low-voltage charger 200 is lower than the inter-terminal voltage (specifically, the rated voltage) of the series-connected first and second storage batteries 31, 32, and is, for example, 400 V.

[0028] The charging voltage of the high-voltage charger 210 is higher than the rated voltage of the series-connected assembly of the first and second storage batteries 31, 32, and is, for example, 800 V. For example, when a user or an operator connects an external charger to each connection portion and charges the first and second storage batteries 31, 32 using the external charger, the high-side charging switch DCRH and the low-side charging switch DCRL are switched to the on state by the control device 100.

[0029] On the other hand, when charging by an external charger is not performed or when an external charger is not connected, the high-side charging switch DCRH and the low-side charging switch DCRL are switched to the OFF state by the control device 100. If the positive-side connection portion and the negative-side connection portion are exposed to the outside from the housing of the power conversion device, they may be touched by a user or worker. By turning off the high-side charging switch DCRH and the low-side charging switch DCRL, electric shock is prevented.

[0030] The low-potential-side electrical path 22L is connected to a portion of the motor-side electrical path 25 between the motor-side switch 60 and the connection switch 80 via a neutral point capacitor 90. The neutral point capacitor 90 is provided with an NC voltage sensor 75 that detects 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: During the charging process when an external charger is connected, a high-frequency current is generated due to switching. The neutral point capacitor 90 is provided to prevent the high-frequency current generated due to switching from flowing from the inverter 20 side into the first and second storage batteries 31, 32 and the external charger.

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

[0032] Next, the on / off states of each switch when the system is connected to an external charger and charging is performed will be described with reference to Figures 2 to 4. Note that in Figure 2 and subsequent figures, the control device 100 and SC voltage sensor 19 are not shown.

[0033] 2 shows the on / off states of each switch when the external charger connected to each connection part of each electrical path 22H, 22L is the low-voltage charger 200. As shown in Fig. 2, when the low-voltage charger 200 is connected, the control device 100 operates the main switches SMRH, SMRL, the inter-battery switch 40, the inter-negative pole bypass switch 50, the motor-side switch 60, the connection switch 80, and the upper and lower arm switches SWH, SWL of the inverter 20 so that the first storage battery 31 is connected in parallel to the low-voltage charger 200 and the second storage battery 32 is connected in parallel to 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 and 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. The control device 100 also 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. As a result, as shown in FIG. 2 , the first storage battery 31 is connected in parallel to the low-voltage charger 200, and the second storage battery 32 is connected in parallel to the low-voltage charger 200 via the inverter 20 and the armature winding 11. As a result, current flows through a closed circuit including the low-voltage charger 200, the high-potential side electrical path 22H, the first storage battery 31, the negative electrode bypass switch 50, and the low-potential side electrical path 22L, and the first storage battery 31 is charged. Furthermore, current flows through 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 storage battery 32, and the low-potential side electrical path 22L, and the second storage battery 32 is charged at a reduced voltage. Note that when the upper-arm switches SWH of multiple phases are turned on, the impedance of the charging path can be reduced. In this embodiment, the mode in which charging is performed in the switch states shown in FIG. 2 is referred to as the "parallel mode."

[0035] 3 shows the on / off states of each switch when the external charger connected to each connection part of each electrical path 22H, 22L is the high-voltage charger 210. As shown in FIG. 3, when the high-voltage charger 210 is connected, the control device 100 operates the main switches SMRH, SMRL, the inter-battery switch 40, the inter-negative pole bypass switch 50, the motor-side switch 60, the connection switch 80, and the upper and lower arm switches SWH, SWL of the inverter 20 so that the first storage battery 31 and the second storage battery 32 are connected in series to the high-voltage charger 210.

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

[0037] Like Fig. 3, Fig. 4 also shows the on / off states of each switch when the external charger connected to each connection part of each electrical path 22H, 22L is the high-voltage charger 210. As in Fig. 3, the first storage battery 31 and the second storage battery 32 are connected in series to the high-voltage charger 210, but the on / off states of each switch in Fig. 4 are different from those in Fig. 3.

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

[0039] Next, referring to Figures 5(a) and 5(b), a case where either the inter-battery switch 40 or the negative electrode bypass switch 50 is stuck on will be described. "Stick on" is one of the switch failure modes, in which the switch contacts are fixed in a connected state (on state). For example, if the switch is a mechanical relay with contacts, the contacts may weld if an arc occurs when the contacts are opened or closed, or if a current exceeding the rated value flows through the contacts. In this case, the switch is fixed in the on state regardless of the control of the control device 100.

[0040] In Figure 5(a), the system is not connected to an external charger, and each switch is in the off state. However, the inter-battery switch 40 is fixed on and does not turn off even when an off command is received from the control device 100. In this state, if, for example, the low-voltage charger 200 is connected, the negative inter-pole bypass switch 50 is turned on as described in Figure 2. At this time, because the inter-battery switch 40 is fixed on, a short-circuit current flows through the closed circuit including the inter-battery switch 40, the negative inter-pole bypass switch 50, and the second storage battery 32, as shown in Figure 5(b).

[0041] 5(a) and 5(b) illustrate an example in which the inter-battery switch 40 is fixed on. However, the same applies when the negative inter-battery bypass switch 50 is fixed on instead of the inter-battery switch 40. That is, if the high-voltage charger 210 is connected when the negative inter-battery bypass switch 50 is fixed on, the inter-battery switch 40 is turned on as described in FIGS. 3 and 4. This causes a short-circuit current to flow through the closed circuit including the inter-battery switch 40, the negative inter-battery bypass switch 50, and the second storage battery 32. Therefore, in any of the parallel mode, series mode, and series neutral mode, either the inter-battery switch 40 or the negative inter-battery bypass switch 50 is turned on during charging. Therefore, it is necessary to determine whether the inter-battery switch 40 and the negative inter-battery bypass switch 50 are fixed on before charging begins or after charging is completed.

[0042] Next, an example of a method for determining whether a switch is stuck on will be described with reference to FIGS. 6 to 8 . Hereinafter, a method for determining whether a switch is stuck on 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. The on / off states of the switches in FIGS. 6 to 8 indicate the on / off states at the time of startup of the power conversion device, i.e., before charging begins. As shown in FIG. 6 , at the time of startup of the power conversion device, the high-side main switch SMRH and the low-side main switch SMRL are turned on. Note that the pre-charge switch SP may be turned on instead of the low-side main switch SMRL. In other words, the "low-side switch provided in the low-side electrical path between the lower arm switch and the negative terminal of the second power storage unit" includes the low-side main switch SMRL and the pre-charge switch SP.

[0043] The inter-battery switch 40, negative electrode bypass switch 50, motor-side switch 60, and connection switch 80 are in the OFF state. Because the inter-battery switch 40 and negative electrode bypass switch 50 are in the OFF state, no current flows through the smoothing capacitor 21, and therefore the voltage Vinv of the smoothing capacitor 21 is 0 V. If 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 during startup of the power conversion device, it determines that the inter-battery switch 40 and negative electrode bypass switch 50 are not stuck ON.

[0044] As in FIG. 6 , the main switches SMRH and SMRL are turned on during startup of the power conversion device. FIG. 7 differs from FIG. 6 in that the inter-battery switch 40 is fixed on. In this case, the first storage battery 31 and the second storage battery 32 are connected in series. As a result, current flows through a closed circuit including the second storage battery 32, the inter-battery switch 40, the first storage battery 31, the high-potential-side electrical path 22H, the smoothing capacitor 21, and the low-potential-side electrical path 22L. The voltage Vinv of the smoothing capacitor 21 becomes 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 when the main switches SMRH and SMRL are turned on during startup of the power conversion device is equal to the sum of the voltages of the first storage battery 31 and the second storage battery 32, it determines that the inter-battery switch 40 is fixed on.

[0045] As in Fig. 6 , the main switches SMRH and SMRL are turned on during startup of the power conversion device in Fig. 8 . Fig. 8 differs from Fig. 6 in that the negative electrode bypass switch 50 is fixed on. In this case, current flows through a 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 becomes 400 V, the same as that of the first storage battery 31. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 when the main switches SMRH and SMRL are turned on during startup of the power conversion device is equal to the voltage of the first storage battery 31, the control device 100 determines that the negative electrode bypass switch 50 is fixed on.

[0046] Next, an example of the operation of the control device 100 will be described with reference to the flowchart in Fig. 9. The initial state of each switch at the start of the flowchart is a state in which an OFF command has been received from the control device 100. In step S101, the control device 100 selects a charging mode. This may be done, for example, 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 acquires the voltage Vinv of the smoothing capacitor 21 detected by the SC voltage sensor 19. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0 V, i.e., if the process of step S103 is YES, the process 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 stuck on. The process proceeds to step S105, where the control device 100 switches the on / off state of each switch based on the charging mode. This starts charging.

[0048] On the other hand, if the process of step S103 is NO, the process proceeds to step S106. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the sum (600 V) of the voltages of the first storage battery 31 and the second storage battery 32, that is, if the process of step S106 is YES, the process proceeds to step S107. In step S107, the control device 100 determines that the inter-battery switch 40 is stuck on. The process proceeds to step S108, where the control device 100 stops charging.

[0049] If the process of step S106 is NO, the process proceeds to step S109. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage (400 V) of the first storage battery 31, that is, if the process of step S109 is YES, the process proceeds to step S110. In step S110, the control device 100 determines that the negative electrode bypass switch 50 is stuck on. Thereafter, the process proceeds to step S108. Note that if the process of step S109 is NO, an unexpected phenomenon may have occurred, and therefore the process proceeds to step S108.

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

[0051] The control device 100 determines whether or not either the inter-battery switch 40 or the negative electrode bypass switch 50 is stuck on before turning on the other switch. If it is determined that one switch is stuck on, the other switch is not turned on, and therefore, as described in Figure 5, a short-circuit current is prevented from flowing through the closed circuit including the inter-battery switch 40, the negative electrode bypass switch 50, and the second storage battery 32.

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

[0053] If the inter-battery switch 40 or the negative electrode bypass switch 50 is stuck 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 or the negative electrode bypass switch 50 is stuck on.

[0054] <Modification of the First Embodiment> The stuck-on state determination described with reference to FIGS. 6 to 8 may be performed when the power conversion device is shut down, rather than when it is started up. When the power conversion device is shut down, i.e., after charging is completed, each switch is controlled to the off state, so the stuck-on state can be determined in the same manner as when it was started up. However, when the power conversion device is shut down, charge accumulates in the smoothing capacitor 21 due to charging. Therefore, in order to determine the stuck-on state when the power conversion device is shut down, it is necessary to discharge the smoothing capacitor 21 so that its voltage is 0 V. One method for discharging the smoothing capacitor 21 is to pass a d-axis current through the inverter 20 and the motor 10. Note that, since the voltage of the smoothing capacitor 21 is 0 V when the power conversion device is started up, such a discharging step is unnecessary.

[0055] Second Embodiment A second embodiment will be described below with reference to Figures 10 to 13. The second embodiment differs from the first embodiment in the switches that are controlled when the power conversion device is started up. Configurations that overlap with those in the first embodiment will be designated by the same reference numerals and will not be described again. The following description will focus on the differences.

[0056] FIG. 10 shows the on / off states of each switch during startup of the power conversion device. As shown in FIG. 10, during startup of the power conversion device, the high-side main switch SMRH, the motor-side switch 60, and the connection switch 80 are turned on. The inter-battery switch 40, the negative-electrode bypass switch 50, and the low-side main switch SMRL are turned off. Because the inter-battery switch 40 and the negative-electrode bypass switch 50 are turned off, no current flows through the smoothing capacitor 21, and therefore the voltage Vinv of the smoothing capacitor 21 is 0 V. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0 V when the high-side main switch SMRH, the motor-side switch 60, and the connection switch 80 are turned on during startup of the power conversion device, the control device 100 determines that the inter-battery switch 40 and the negative-electrode bypass switch 50 are not stuck on.

[0057] As in Fig. 10 , when the power conversion device is started up, the high-side main switch SMRH, the motor-side switch 60, and the connection switch 80 are turned on in Fig. 11 . The difference between Fig. 11 and Fig. 10 is that the inter-battery switch 40 is fixed on. In this case, current flows through a closed circuit including the inter-battery switch 40, the first storage battery 31, the high-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 400 V, the same as that of the first storage battery 31. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage of the first storage battery 31 when the high-side main switch SMRH, the motor-side switch 60, and the connection switch 80 are turned on during start-up of the power conversion device, it determines that the inter-battery switch 40 is fixed on.

[0058] As in Fig. 10 , when the power conversion device is started up, the high-potential-side main switch SMRH, the motor-side switch 60, and the connection switch 80 are turned on in Fig. 12 . Fig. 12 differs from Fig. 10 in that the negative-electrode bypass switch 50 is fixed on. In this case, the first storage battery 31 and the second storage battery 32 are connected in parallel. As a result, a current flows through a closed circuit including the second storage battery 32, the negative-electrode bypass switch 50, 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. The voltage Vinv of the smoothing capacitor 21 becomes equal to the voltage difference (200 V) between the voltages of the first storage battery 31 and the second storage 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 storage battery 31 and the voltage of the second storage battery 32, it determines that the negative electrode bypass switch 50 is stuck on.

[0059] Next, an example of the operation of the control device 100 will be described with reference to the flowchart in Fig. 13. The initial state of each switch at the start of the flowchart is a state in which an OFF command has been 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-side main switch SMRH, the motor-side switch 60, and the connection switch 80 to acquire the voltage Vinv of the smoothing capacitor 21. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0 V, i.e., if the process of step S203 is YES, the process 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 stuck on. The process proceeds to step S205, where the control device 100 switches the on / off state of each switch based on the charging mode, thereby starting charging.

[0061] On the other hand, if the process of step S203 is NO, the process proceeds to step S206. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage (400 V) of the first storage battery 31, that is, if the process of step S206 is YES, the process proceeds to step S207. In step S207, the control device 100 determines that the inter-battery switch 40 is stuck on. The process proceeds to step S208, where the control device 100 stops charging.

[0062] If the process of step S206 is NO, the process proceeds to step S209. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage difference (200 V) between the voltage of the first storage battery 31 and the voltage of the second storage battery 32, that is, if the process of step S209 is YES, the process proceeds to step S210. In step S210, the control device 100 determines that the negative electrode bypass switch 50 is stuck on. Thereafter, the process proceeds to step S208. Note that if the process of step S209 is NO, an unexpected phenomenon may have occurred, and the process proceeds to step S208.

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

[0064] When starting up the power conversion device, i.e., before starting charging, 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 negative electrode bypass switch 50 is stuck on based on the voltage Vinv of the smoothing capacitor 21 at that time. With this configuration, it is possible to determine whether the inter-battery switch 40 or the negative electrode bypass switch 50 is stuck on or not, without actually turning on or off the inter-battery switch 40 or the negative electrode bypass switch 50.

[0065] If the inter-battery switch 40 or the negative electrode bypass switch 50 is stuck 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 or the negative electrode bypass switch 50 is stuck on.

[0066] <Modification of the Second Embodiment> The stuck-on determination described with reference to Figures 10 to 12 may be performed when the power conversion device is shut down, rather than when it is started up. When the power conversion device is shut down, that is, after charging is completed, each switch is controlled to the off state, so the stuck-on state can be determined in the same way as when it is started up. However, when the power conversion device is shut down, charge accumulates in the smoothing capacitor 21 due to charging. Therefore, in order to determine the stuck-on state when the power conversion device is shut down, it is necessary to discharge the smoothing capacitor 21 so that the voltage of the smoothing capacitor 21 becomes 0 V. The method of discharging the smoothing capacitor 21 is the same as in the modification of the first embodiment.

[0067] Third Embodiment A third embodiment will be described below with reference to FIG. 14 . Components that overlap with those of the first embodiment will be designated by the same reference numerals, and their description will be omitted. Differences will be mainly described below. FIG. 14 is a configuration diagram of a power conversion device according to the third embodiment. As shown in FIG. 14 , the power conversion device includes at least one of an inter-battery switch voltage sensor 76 that detects the voltage across the inter-battery switch 40, a bypass switch voltage sensor 77 that detects the voltage across the negative electrode bypass switch 50, an inter-terminal voltage sensor 78 that detects the inter-terminal voltage between the positive electrode terminal of the first storage battery 31 and the positive electrode terminal of the second storage battery 32, and a PN voltage sensor 79 that detects the PN voltage between the high potential side electrical path 22H and the low potential side electrical path 22L.

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

[0069] First, a determination method using the voltage across the inter-battery switch 40 will be described with reference to the flowchart in Figure 15. In step S301, the control device 100 determines whether the voltage VB across the inter-battery switch 40 detected by the inter-battery switch voltage sensor 76 is 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32. In this embodiment, when the inter-battery switch 40 and the negative electrode bypass switch 50 are not stuck on and are in the off state, the voltage VB across the inter-battery switch 40 is 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32. Therefore, if the process in step S301 is YES, the process proceeds to step S302, where the control device 100 determines that the inter-battery switch 40 and the negative electrode bypass switch 50 are not stuck on.

[0070] On the other hand, if the process in step S301 is NO, the process 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 this embodiment, if the inter-battery switch 40 is stuck on, the voltage VB across the inter-battery switch 40 is 0 V. Therefore, if the process in step S303 is YES, the process proceeds to step S304, where the control device 100 determines that the inter-battery switch 40 is stuck on.

[0071] If the process in step S303 is NO, the process 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 (200 V) of the second storage battery 32. In this embodiment, if the negative electrode bypass switch 50 is stuck on, the voltage VB across the inter-battery switch 40 becomes equal to the voltage of the second storage battery 32. Therefore, if the process in step S305 is YES, the process proceeds to step S306, where the control device 100 determines that the negative electrode bypass switch 50 is stuck on.

[0072] After steps S304 and S306, the process proceeds to step S307, where the control device 100 stops charging. Note that if the process of step S305 is NO, the process also proceeds to step S307.

[0073] Next, a determination method using the voltage across the negative electrode bypass switch 50 will be described with reference to the flowchart in Fig. 16. In step S401, the control device 100 determines whether the voltage VP across the negative electrode bypass switch 50 detected by the bypass switch voltage sensor 77 is equal to the voltage (400 V) of the first storage battery 31. In this embodiment, when the inter-battery switch 40 and the negative electrode bypass switch 50 are not stuck on and are in the off state, the voltage VP across the negative electrode bypass switch 50 becomes equal to the voltage of the first storage battery 31. Therefore, if the process in step S401 is YES, the process proceeds to step S402, where the control device 100 determines that the inter-battery switch 40 and the negative electrode bypass switch 50 are not stuck on.

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

[0075] If the process in step S403 is NO, the process proceeds to step S405. In step S405, the control device 100 determines whether the voltage VP across the negative electrode-to-negative electrode bypass switch 50 is 0 V. In the present embodiment, if the negative electrode-to-negative electrode bypass switch 50 is stuck on, the voltage VP across the negative electrode-to-negative electrode bypass switch 50 is 0 V. Therefore, if the process in step S405 is YES, the process proceeds to step S406, and the control device 100 determines that the negative electrode-to-negative electrode bypass switch 50 is stuck on.

[0076] After steps S404 and S406, the process proceeds to step S407, where the control device 100 stops charging. Note that if the process of step S405 is NO, the process also proceeds to step S407.

[0077] Next, a determination method using the inter-terminal voltage will be described with reference to the flowchart in Fig. 17. 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 this embodiment, if the inter-battery switch 40 and the negative electrode bypass switch 50 are not stuck on and are in the OFF state, the inter-terminal voltage VT is equal to the voltage of the second storage battery 32. Therefore, if the process in step S501 is YES, the process proceeds to step S502, where the control device 100 determines that the inter-battery switch 40 and the negative electrode bypass switch 50 are not stuck on.

[0078] On the other hand, if the process in step S501 is NO, the process 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 this embodiment, if the inter-battery switch 40 is stuck on, the inter-terminal voltage VT becomes equal to the voltage of the first storage battery 31. Therefore, if the process in step S503 is YES, the process proceeds to step S504, where the control device 100 determines that the inter-battery switch 40 is stuck on.

[0079] If the process of step S503 is NO, the process 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, if the negative electrode bypass switch 50 is stuck on, the inter-terminal voltage VT becomes equal to the voltage difference between the voltage of the first storage battery 31 and the voltage of the second storage battery 32. Therefore, if the process of step S505 is YES, the process proceeds to step S506, and the control device 100 determines that the negative electrode bypass switch 50 is stuck on.

[0080] After steps S504 and S506, the process proceeds to step S507, where the control device 100 stops charging. Note that if the process of step S505 is NO, the process also proceeds to step S507.

[0081] Next, a determination method using the PN voltage will be described with reference to the flowchart in Fig. 18. In step S601, the control device 100 determines whether the PN voltage VPN detected by the PN voltage sensor 79 is 0 V. In this embodiment, if the inter-battery switch 40 and the negative electrode bypass switch 50 are not stuck on and are in the OFF state, the PN voltage VPN is 0 V. Therefore, if the process in step S601 is YES, the process proceeds to step S602, and the control device 100 determines that the inter-battery switch 40 and the negative electrode bypass switch 50 are not stuck on.

[0082] On the other hand, if the process in step S601 is NO, the process proceeds to step S603. In step S603, the control device 100 determines whether the PN voltage VPN is 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32. In this embodiment, if the inter-battery switch 40 is stuck on, the PN voltage VPN is 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32. Therefore, if the process in step S603 is YES, the process proceeds to step S604, and the control device 100 determines that the inter-battery switch 40 is stuck on.

[0083] If the process in step S603 is NO, the process proceeds to step S605. In step S605, the control device 100 determines whether the PN voltage VPN is equal to the voltage (400 V) of the first storage battery 31. In the present embodiment, if the negative electrode bypass switch 50 is stuck on, the PN voltage VPN becomes equal to the voltage of the first storage battery 31. Therefore, if the process in step S605 is YES, the process proceeds to step S606, and the control device 100 determines that the negative electrode bypass switch 50 is stuck on.

[0084] After steps S604 and S606, the process proceeds to step S607, where the control device 100 stops charging. Note that if the process of step S605 is NO, the process also proceeds to step S607.

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

[0086] When the power conversion device is started, i.e., before charging starts, the control device 100 determines whether the inter-battery switch 40 or the negative electrode bypass switch 50 is stuck on by using any of the voltages detected by the voltage sensors 76 to 79. With this configuration, it is possible to determine whether the inter-battery switch 40 or the negative electrode bypass switch 50 is stuck on without actually turning the inter-battery switch 40 or the negative electrode bypass switch 50 on or off.

[0087] If the inter-battery switch 40 or the negative electrode bypass switch 50 is stuck on, the voltages detected by the voltage sensors 76 to 79 will change. Therefore, by focusing on one of the voltages detected by the voltage sensors 76 to 79, it is possible to determine which of the inter-battery switch 40 and the negative electrode bypass switch 50 is stuck on.

[0088] 15 to 18 may be performed when the power conversion device is shut down, rather than when it is started up. When the power conversion device is shut down, that is, after charging is completed, each switch is controlled to the off state, so that it is possible to determine whether the switch is stuck on in the same way as when it is started up.

[0089] <Fourth Embodiment> A fourth embodiment will be described below. In the previous embodiment, it was described that the inter-battery switch 40 and the negative electrode bypass switch 50 were determined to be stuck on, and charging was started if it was determined that the inter-battery switch 40 and the negative electrode bypass switch 50 were not stuck on. After it was determined that the inter-battery switch 40 and the negative electrode bypass switch 50 were not stuck on, it may be determined whether or not another switch has failed before charging was started. Below, an example of a determination method will be described for each of the series mode, parallel mode, and series neutral point mode.

[0090] 19 is a flow chart for the series mode, which is a flow after it is determined that the inter-battery switch 40 and the negative electrode bypass switch 50 are not stuck on.

[0091] In step S701, the control device 100 turns on the inter-battery switch 40. In the following step S702, the control device 100 turns on the pre-charge switch SP and acquires the voltage Vinv of the smoothing capacitor 21. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0 V, that is, if the process of step S703 is YES, the process proceeds to step S704.

[0092] In step S704, the control device 100 turns on the high-side main switch SMRH and acquires the voltage Vinv of the smoothing capacitor 21. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32, i.e., if the process of step S706 is YES, the process proceeds to step S708. In step S708, the control device 100 turns on the low-side main switch SMRL. In the following step S709, the control device 100 turns off the pre-charge switch SP. In the following step S710, the control device 100 starts charging.

[0093] If the determination in step S703 is NO, the process proceeds to step S705, where the control device 100 determines that the high-side main switch SMRH is stuck on. The process proceeds to step S711, where the control device 100 stops charging.

[0094] If the processing in step S706 is NO, the processing proceeds to step S707, where the control device 100 determines that the high potential side main switch SMRH is stuck off. "Stuck off" is a failure mode in which the switch contacts are fixed in a disconnected state. The processing proceeds to step S711, where the control device 100 stops charging. If the processing in step S706 is NO, this means that although the control device 100 output an ON command to the high potential side main switch SMRH in step S704, the high potential side main switch SMRH did not turn on because it was stuck off.

[0095] 20 is a flow chart for the parallel mode, which shows the flow after it is determined that the inter-battery switch 40 and the negative electrode bypass switch 50 are not stuck on.

[0096] In step S801, the control device 100 turns on the negative electrode bypass switch 50. In the following step S802, the control device 100 turns on the precharge switch SP and acquires 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. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0 V, that is, if the process of step S803 is YES, the process proceeds to step S804.

[0097] If the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to 0 V, i.e., if the process of step S804 is YES, the process proceeds to step S807. In step S807, the control device 100 turns on the high-side main switch SMRH and acquires the voltage Vinv of the smoothing capacitor 21. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage (400 V) of the first storage battery 31, i.e., if the process of step S808 is YES, the process proceeds to step S809. In step S809, the control device 100 turns on the motor-side switch 60 and acquires the voltage Vcb of the neutral point capacitor 90.

[0098] If the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to the voltage (200 V) of the second storage battery 32, i.e., if the process of step S811 is YES, the process proceeds to step S812. In step S812, the control device 100 turns on the low-potential side main switch SMRL. In the following step S814, the control device 100 turns off the pre-charge switch SP.

[0099] In the following 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 this determination in step S815 is that if 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 storage battery side via the upper arm diode DH. If the processing in step S815 is YES, the processing proceeds to step S816. If the processing in step S815 is NO, the processing proceeds to step S818, where it is determined whether the phenomenon in which the voltage Vcb of the neutral point capacitor 90 is greater than the voltage Vinv of the smoothing capacitor 21 has occurred a predetermined number of times or more. If it is determined that the phenomenon in which the voltage Vcb of the neutral point capacitor 90 is greater than the voltage Vinv of the smoothing capacitor 21 has occurred a predetermined number of times or more, that is, if the processing in step S818 is YES, the processing proceeds to step S819, where the control device 100 stops charging.

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

[0101] If the processing in step S803 is NO, the process proceeds to step S805, where the control device 100 determines that the high-potential side main switch SMRH is stuck on. If the processing in step S804 is NO, the process proceeds to step S806, where the control device 100 determines that the motor-side switch 60 is stuck on. If the processing in step S808 is NO, the process proceeds to step S810, where the control device 100 determines that the high-potential side main switch SMRH is stuck off. If the processing in step S811 is NO, the process proceeds to step S813, where the control device 100 determines that the motor-side switch 60 is stuck off. After steps S805, S806, S810, and S813, the process proceeds to step S819, where the control device 100 stops charging.

[0102] A NO result in step S808 means that although the control device 100 output an ON command to the high-potential side main switch SMRH in step S807, the high-potential side main switch SMRH was not turned ON because it was stuck OFF. Also, a NO result in step S811 means that although the control device 100 output an ON command to the motor-side switch 60 in step S809, the motor-side switch 60 was not turned ON because it was stuck OFF.

[0103] In the flow of Fig. 20, the motor-side switch 60 may be turned on before the high-potential-side main switch SMRH. The flow in this case will be described with reference to Fig. 21. However, since the processing of steps S901, S902, S903, S904, S905, S906, S914, S916, S917, S918, S919, S920, and S921 in Fig. 21 is the same as the processing of steps S801, S802, S803, S804, S805, S806, S812, S814, S815, S816, S817, S818, and S819 in Fig. 20, description thereof will be omitted.

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

[0105] If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0 V, i.e., if the process of step S909 is YES, the process proceeds to step S911. In step S911, the control device 100 turns on the high-side main switch SMRH and acquires the voltage Vinv of the smoothing capacitor 21. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage (400 V) of the first storage battery 31, i.e., if the process of step S913 is YES, the process proceeds to step S914.

[0106] If the processing in step S908 is NO, the process proceeds to step S910, where the control device 100 determines that the motor-side switch 60 is stuck off. If the processing in step S909 is NO, the process proceeds to step S912, where the control device 100 determines that the connection switch 80 is stuck on. If the processing in step S913 is NO, the process proceeds to step S915, where the control device 100 determines that the high-potential-side main switch SMRH is stuck off.

[0107] A NO result in step S908 means that although the control device 100 output an ON command to the motor-side switch 60 in step S907, the motor-side switch 60 did not turn ON because it was stuck OFF. Also, a NO result in step S913 means that although the control device 100 output an ON command to the high-potential side main switch SMRH in step S911, the high-potential side main switch SMRH did not turn ON because it was stuck OFF.

[0108] 22 is a flowchart for the series neutral mode, which is a flow that is executed after it is determined that the inter-battery switch 40 and the negative electrode bypass switch 50 are not stuck on.

[0109] In step S1001, the control device 100 turns on the inter-battery switch 40. In the following step S1002, the control device 100 turns on the pre-charge switch SP and acquires the voltage of the smoothing capacitor 21 and the voltage Vcb of the neutral point capacitor 90. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0 V, that is, if the process of step S1003 is YES, the process proceeds to step S1004.

[0110] If the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to 0 V, i.e., if the process of step S1004 is YES, the process proceeds to step S1007. In step S1007, the control device 100 turns on the high-side main switch SMRH and acquires the voltage Vinv of the smoothing capacitor 21. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32, i.e., if the process of step S1008 is YES, the process proceeds to step S1009. In step S1009, the control device 100 turns on the motor-side switch 60 and acquires the voltage Vcb of the neutral point capacitor 90.

[0111] If the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to the voltage (200 V) of the second storage battery 32, i.e., if the process of step S1011 is YES, the process proceeds to step S1012. In step S1012, the control device 100 turns on the low-potential side main switch SMRL. In the following step S1014, the control device 100 turns off the pre-charge switch SP.

[0112] In the following 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. If the process of step S1015 is YES, the process proceeds to step S1016. If the process of step S1015 is NO, the process proceeds to step S1018, where it is determined whether the phenomenon in which the voltage Vcb of the neutral point capacitor 90 is greater than the voltage Vinv of the smoothing capacitor 21 has occurred a predetermined number of times or more. If it is determined that the phenomenon in which the voltage Vcb of the neutral point capacitor 90 is greater than the voltage Vinv of the smoothing capacitor 21 has occurred a predetermined number of times or more, that is, if the process of step S1018 is YES, the process proceeds to step S1019, where the control device 100 stops charging.

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

[0114] If the processing in step S1003 is NO, the process proceeds to step S1005, where the control device 100 determines that the high-potential side main switch SMRH is stuck on. If the processing in step S1004 is NO, the process proceeds to step S1006, where the control device 100 determines that the motor-side switch 60 is stuck on. If the processing in step S1008 is NO, the process proceeds to step S1010, where the control device 100 determines that the high-potential side main switch SMRH is stuck off. If the processing in step S1011 is NO, the process proceeds to step S1013, where the control device 100 determines that the motor-side switch 60 is stuck off. After steps S1005, S1006, S1010, and S1013, the process proceeds to step S1019, where the control device 100 stops charging.

[0115] A NO result in step S1008 means that although the control device 100 output an ON command to the high-potential side main switch SMRH in step S1007, the high-potential side main switch SMRH was not turned ON because it was stuck OFF. Also, a NO result in step S1011 means that although the control device 100 output an ON command to the motor-side switch 60 in step S1009, the motor-side switch 60 was not turned ON because it was stuck OFF.

[0116] In the flow of Fig. 22, the motor-side switch 60 may be turned on before the high-potential-side main switch SMRH. The flow in this case will be described with reference to Fig. 23. However, since the processing of steps S1101, S1102, S1103, S1104, S1105, S1106, S1114, S1116, S1117, S1118, S1119, S1120, and S1121 in Fig. 23 is the same as the processing of steps S1001, S1002, S1003, S1004, S1005, S1006, S1012, S1014, S1015, S1016, S1017, S1018, and S1019 in Fig. 22, description thereof will be omitted.

[0117] In step S1107, the control device 100 turns on the motor-side switch 60 and acquires the voltage Vinv of the neutral point capacitor 90 and the smoothing capacitor 21. If the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to the voltage (200 V) of the second storage battery 32, that is, if the process of step S1108 is YES, the process proceeds to step S1109.

[0118] If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0 V, i.e., if the process of step S1109 is YES, the process proceeds to step S1111. In step S1111, the control device 100 turns on the high-side main switch SMRH and acquires the voltage Vinv of the smoothing capacitor 21. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32, i.e., if the process of step S1113 is YES, the process proceeds to step S1114.

[0119] If the processing in step S1108 is NO, the process proceeds to step S1110, where the control device 100 determines that the motor-side switch 60 is stuck off. If the processing in step S1109 is NO, the process proceeds to step S1112, where the control device 100 determines that the connection switch 80 is stuck on. If the processing in step S1113 is NO, the process proceeds to step S1115, where the control device 100 determines that the high-potential-side main switch SMRH is stuck off.

[0120] A NO result in step S1108 means that although the control device 100 output an ON command to the motor-side switch 60 in step S1107, the motor-side switch 60 did not turn ON because it was stuck OFF. Also, a NO result in step S1113 means that although the control device 100 output an ON command to the high-potential side main switch SMRH in step S1111, the high-potential side main switch SMRH did not turn ON because it was stuck OFF.

[0121] The control device 100 shuts down the power conversion device after charging is complete. At this time, the power conversion device may be shut down according to the flow shown in FIG. 24. The flow shown in FIG. 24 starts after charging is complete. In step S1201, the control device 100 turns off all switches except the connection switch 80. In the following step S1202, the control device 100 discharges the neutral point capacitor 90. A method for discharging the neutral point capacitor 90 is to boost the voltage using the inverter 30 and transfer the charge of the neutral point capacitor 90 to the smoothing capacitor 21. After discharging the neutral point capacitor 90 until the voltage of the neutral point capacitor 90 reaches 0 V, the process proceeds to step S1203, where the control device 100 turns off 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 stuck on, the charge of the smoothing capacitor 21 is not transferred to the neutral point capacitor 90, and the voltage Vcb of the neutral point capacitor 90 is 0 V. If the control device 100 determines that the voltage Vcb of the neutral point capacitor 90 is equal to 0 V, that is, if the process of step S1205 is YES, the process proceeds to step S1206. In step S1206, the control device 100 discharges the smoothing capacitor 21 until the voltage of the smoothing capacitor 21 reaches 0 V, thereby shutting down the power conversion device.

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

[0124] If the process in step S1205 is NO, this means that although the control device 100 output an OFF command to the connection switch 80 in step S1203, the connection switch 80 did not enter the OFF state because it was stuck ON.

[0125] Fifth Embodiment The fifth embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in FIG. 25 , 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 negative-electrode bypass switch 50 shown in FIG. 1 . The power conversion device also includes a neutral point capacitor 91 and an NC voltage sensor 75A detecting the voltage of the neutral point capacitor 91 between the motor-side electrical path 25 and the high-potential-side electrical path 22H, but does not include the neutral point capacitor 90 and the NC voltage sensor 75 shown in FIG. 1 . 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 closer to the first storage battery 31 than the inter-battery switch 40. The motor-side electrical path 25 includes a motor-side switch 61. The voltage of the first storage battery 31 is 200 V, and the voltage of the second storage battery 32 is 400 V.

[0126] An example of a method for determining whether the inter-battery switch 40 or the inter-positive electrode bypass switch 51 is stuck on in the circuit configuration shown in Fig. 25 will be described with reference to the flowchart of Fig. 26. The initial state of each switch at the start of the flowchart is a state in which it has received an OFF command 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 acquire the voltage Vinv of the smoothing capacitor 21. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0 V, i.e., if the process of step S1303 is YES, the process proceeds to step S1304. In step S1304, the control device 100 determines that the inter-battery switch 40 and the inter-positive electrode bypass switch 51 are not stuck on. The process proceeds to step S1305, where the control device 100 switches the on / off state of each switch based on the charging mode. This starts charging.

[0128] On the other hand, if the process of step S1303 is NO, the process proceeds to step S1306. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the sum (600 V) of the voltages of the first storage battery 31 and the second storage battery 32, that is, if the process of step S1306 is YES, the process proceeds to step S1307. In step S1307, the control device 100 determines that the inter-battery switch 40 is stuck on. The process proceeds to step S1308, where the control device 100 stops charging.

[0129] If the process of step S1306 is NO, the process proceeds to step S1309. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to the voltage (400 V) of the second storage battery 32, that is, if the process of step S1309 is YES, the process proceeds to step S1310. In step S1310, the control device 100 determines that the positive electrode bypass switch 51 is stuck on. Thereafter, the process proceeds to step S1308. Note that if the process of step S1309 is NO, an unexpected phenomenon may have occurred, and the process proceeds to step S1308.

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

[0131] When starting up the power conversion device, i.e., before starting charging, the control device 100 turns on the main switches SMRH, SMRL, and determines whether the inter-battery switch 40 or the positive electrode bypass switch 51 is stuck on based on the voltage Vinv of the smoothing capacitor 21 at that time. With this configuration, it is possible to determine whether the inter-battery switch 40 or the positive electrode bypass switch 51 is stuck on without actually turning the inter-battery switch 40 or the positive electrode bypass switch 51 on or off.

[0132] <First Modification of Fifth Embodiment> Whether the inter-battery switch 40 or the inter-positive bypass switch 51 is stuck on may be determined according to the flowchart shown in Fig. 27. The flowchart will be described below. At the start of the flowchart, the initial state of each switch is a state in which it has received an OFF command from the control device 100.

[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 acquire the voltage Vinv of the smoothing capacitor 21. If the control device 100 determines that the voltage Vinv of the smoothing capacitor 21 is equal to 0 V, i.e., if the process of step S1403 is YES, the process proceeds to step S1404. In step S1404, the control device 100 determines that the inter-battery switch 40 and the inter-positive electrode bypass switch 51 are not stuck on. The process proceeds to step S1405, where the control device 100 switches the on / off state of each switch based on the charging mode. This starts charging.

[0134] On the other hand, if the process of step S1403 is NO, the process proceeds to step S1406. If 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, if the process of step S1406 is YES, the process proceeds to step S1407. In step S1407, the control device 100 determines that the inter-battery switch 40 is stuck on. The process proceeds to step S1408, where the control device 100 stops charging.

[0135] If the process of step S1406 is NO, the process proceeds to step S1409. If 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, if the process of step S1409 is YES, the process proceeds to step S1410. In step S1410, the control device 100 determines that the positive electrode bypass switch 51 is stuck on. Thereafter, the process proceeds to step S1408. Note that if the process of step S1409 is NO, an unexpected phenomenon may have occurred, and the process proceeds to step S1408.

[0136] If the inter-battery switch 40 or the positive electrode bypass switch 51 is stuck 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 or the positive electrode bypass switch 51 is stuck on.

[0137] The stuck-on determination described with reference to Figures 26 and 27 may be performed when the power conversion device is shut down, rather than when it is started up. When the power conversion device is shut down, that is, after charging is completed, each switch is controlled to the off state, so the stuck-on state can be determined in the same way as when it is started up. However, when the power conversion device is shut down, charge accumulates in the smoothing capacitor 21 due to charging. Therefore, in order to determine the stuck-on state when the power conversion device is shut down, it is necessary to discharge the smoothing capacitor 21 so that the voltage of the smoothing capacitor 21 is 0 V. The method of discharging the smoothing capacitor 21 is the same as in the modified example of the first embodiment.

[0138] Sixth Embodiment The sixth embodiment will be described below with reference to the drawings, focusing on differences from the fifth embodiment. As shown in Fig. 28 , the power conversion device includes at least one of an inter-battery switch voltage sensor 86 that detects the voltage across the inter-battery switch 40, a bypass switch voltage sensor 87 that detects the voltage across the inter-positive bypass switch 51, an inter-terminal voltage sensor 88 that detects the inter-terminal voltage between the negative terminal of the first storage battery 31 and the negative terminal of the second storage battery 32, and a PN voltage sensor 89 that detects the PN voltage between the high potential side electrical path 22H and the low potential side electrical path 22L.

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

[0140] First, a determination method using the voltage across the inter-battery switch 40 will be described with reference to the flowchart in Figure 29. In step S1501, the control device 100 determines whether the voltage VB2 across the inter-battery switch 40 detected by the inter-battery switch voltage sensor 86 is 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32. In this embodiment, when the inter-battery switch 40 and the positive electrode bypass switch 51 are not stuck on and are in the off state, the voltage VB2 across the inter-battery switch 40 is 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32. Therefore, if the process in step S1501 is YES, the process proceeds to step S1502, where the control device 100 determines that the inter-battery switch 40 and the positive electrode bypass switch 51 are not stuck on.

[0141] On the other hand, if the process in step S1501 is NO, the process 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 this embodiment, if the inter-battery switch 40 is stuck on, the voltage VB2 across the inter-battery switch 40 is 0 V. Therefore, if the process in step S1503 is YES, the process proceeds to step S1504, and the control device 100 determines that the inter-battery switch 40 is stuck on.

[0142] If the process in step S1503 is NO, the process 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 (200 V) of the first storage battery 31. In this embodiment, if the positive electrode bypass switch 51 is stuck on, the voltage VB2 across the inter-battery switch 40 becomes equal to the voltage of the first storage battery 31. Therefore, if the process in step S1505 is YES, the process proceeds to step S1506, where the control device 100 determines that the positive electrode bypass switch 51 is stuck on.

[0143] After steps S1504 and S1506, the process proceeds to step S1507, where the control device 100 stops charging. Note that if the process of step S1505 is NO, the process also proceeds to step S1507.

[0144] Next, a determination method using the voltage across the positive electrode bypass switch 51 will be described with reference to the flowchart in Fig. 30. In step S1601, the control device 100 determines whether the voltage VP2 across the positive electrode bypass switch 51 detected by the bypass switch voltage sensor 87 is equal to the voltage (400 V) of the second storage battery 32. In this embodiment, when the inter-battery switch 40 and the positive electrode bypass switch 51 are not stuck on and are in the OFF state, the voltage VP2 across the positive electrode bypass switch 51 is equal to the voltage of the second storage battery 32. Therefore, if the process in step S1601 is YES, the process proceeds to step S1602, where the control device 100 determines that the inter-battery switch 40 and the positive electrode bypass switch 51 are not stuck on.

[0145] On the other hand, if the process in step S1601 is NO, the process 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 (200 V) of the first storage battery 31. In this embodiment, if the inter-battery switch 40 is stuck on, the voltage VP2 across the positive electrode bypass switch 51 becomes equal to the voltage of the first storage battery 31. Therefore, if the process in step S1603 is YES, the process proceeds to step S1604, where the control device 100 determines that the inter-battery switch 40 is stuck on.

[0146] If the process in step S1603 is NO, the process 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, if the positive electrode bypass switch 51 is stuck on, the voltage VP2 across the positive electrode bypass switch 51 is 0 V. Therefore, if the process in step S1605 is YES, the process proceeds to step S1606, where the control device 100 determines that the positive electrode bypass switch 51 is stuck on.

[0147] After steps S1604 and S1606, the process proceeds to step S1607, where the control device 100 stops charging. Note that if the process of step S1605 is NO, the process also proceeds to step S1607.

[0148] Next, a determination method using the inter-terminal voltage will be described with reference to the flowchart in Fig. 31. In step S1701, the control device 100 determines whether the inter-terminal voltage VT2 detected by the inter-terminal voltage sensor 88 is equal to the voltage of the first storage battery 31. In this embodiment, if the inter-battery switch 40 and the positive electrode bypass switch 51 are not stuck on and are in the OFF state, the inter-terminal voltage VT2 is equal to the voltage of the first storage battery 31. Therefore, if the process in step S1701 is YES, the process proceeds to step S1702, where the control device 100 determines that the inter-battery switch 40 and the positive electrode bypass switch 51 are not stuck on.

[0149] On the other hand, if the process of step S1701 is NO, the process 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 this embodiment, if the inter-battery switch 40 is stuck on, the inter-terminal voltage VT2 becomes equal to the voltage of the second storage battery 32. Therefore, if the process of step S1703 is YES, the process proceeds to step S1704, where the control device 100 determines that the inter-battery switch 40 is stuck on.

[0150] If the process of step S1703 is NO, the process 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, if the inter-positive electrode bypass switch 51 is stuck on, the inter-terminal voltage VT2 becomes equal to the voltage difference between the voltage of the first storage battery 31 and the voltage of the second storage battery 32. Therefore, if the process of step S1705 is YES, the process proceeds to step S1706, where the control device 100 determines that the inter-positive electrode bypass switch 51 is stuck on.

[0151] After steps S1704 and S1706, the process proceeds to step S1707, where the control device 100 stops charging. Note that if the process of step S1705 is NO, the process also proceeds to step S1707.

[0152] Next, a determination method using the PN voltage will be described with reference to the flowchart in Fig. 32. In step S1801, the control device 100 determines whether the PN voltage VPN2 detected by the PN voltage sensor 89 is 0 V. In this embodiment, if the inter-battery switch 40 and the positive electrode bypass switch 51 are not stuck on and are in the OFF state, the PN voltage VPN2 is 0 V. Therefore, if the process in step S1801 is YES, the process proceeds to step S1802, where the control device 100 determines that the inter-battery switch 40 and the positive electrode bypass switch 51 are not stuck on.

[0153] On the other hand, if the process in step S1801 is NO, the process proceeds to step S1803. In step S1803, the control device 100 determines whether the PN voltage VPN2 is 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32. In this embodiment, if the inter-battery switch 40 is stuck on, the PN voltage VPN2 is 600 V, which is the sum of the voltages of the first storage battery 31 and the second storage battery 32. Therefore, if the process in step S1803 is YES, the process proceeds to step S1804, where the control device 100 determines that the inter-battery switch 40 is stuck on.

[0154] If the process in step S1803 is NO, the process proceeds to step S1805. In step S1805, the control device 100 determines whether the PN voltage VPN2 is equal to the voltage (400 V) of the second storage battery 32. In the present embodiment, if the positive electrode bypass switch 51 is stuck on, the PN voltage VPN2 becomes equal to the voltage of the second storage battery 32. Therefore, if the process in step S1805 is YES, the process proceeds to step S1806, where the control device 100 determines that the positive electrode bypass switch 51 is stuck on.

[0155] After steps S1804 and S1806, the process proceeds to step S1807, where the control device 100 stops charging. Note that if the process of step S1805 is NO, the process also proceeds to step S1807.

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

[0157] When the power conversion device is started, i.e., before charging starts, the control device 100 determines whether the inter-battery switch 40 or the positive electrode bypass switch 51 is stuck on by using one of the voltages detected by the voltage sensors 86 to 89. With this configuration, it is possible to determine whether the inter-battery switch 40 or the positive electrode bypass switch 51 is stuck on without actually turning the inter-battery switch 40 or the positive electrode bypass switch 51 on or off.

[0158] If the inter-battery switch 40 or the positive electrode bypass switch 51 is stuck on, there will be a change in the voltage detected by each of the voltage sensors 86 to 89. Therefore, by focusing on one of the voltages detected by each of the voltage sensors 86 to 89, it is possible to determine which of the inter-battery switch 40 and the positive electrode bypass switch 51 is stuck on.

[0159] 29 to 32 may be performed when the power conversion device is shut down, rather than when it is started up. When the power conversion device is shut down, that is, after charging is completed, each switch is controlled to the off state, so that it is possible to determine whether the switch is stuck on in the same way as when it is started up.

[0160] Seventh Embodiment Hereinafter, a seventh embodiment will be described with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in Fig. 33 , the power conversion device further includes an inter-positive electrode bypass switch 51 that connects the positive electrode terminal of the second storage battery 32 and the high potential side electrical path 22H.

[0161] The control device 100 can, for example, turn on the positive electrode bypass switch 51 and turn off the negative electrode bypass switch 50, the battery switch 40, the motor side switch 60, the connection switch 80, the high potential side main switch SMRH, and the low potential side main switch SMRL, and can charge the second storage battery 32 individually using the low voltage charger 200.

[0162] Eighth Embodiment An eighth embodiment will now be described with reference to the drawings, focusing on differences from the fifth embodiment. In this embodiment, as shown in Fig. 34 , 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 can, for example, turn on the negative electrode bypass switch 50 and turn off the positive electrode bypass switch 51, the battery switch 40, the motor side switch 60, the connection switch 80, the high potential side main switch SMRH, and the low potential side main switch SMRL, and can charge the first storage battery 31 individually using the low voltage charger 200.

[0164] Ninth Embodiment A ninth embodiment will now be described with reference to the drawings, focusing on differences from the above-described embodiments. In this embodiment, as shown in Fig. 35 , a motor-side switch is provided that connects the neutral point of the armature winding 11 to the negative terminal of the first storage battery 31, and also a switch that connects the neutral point of the armature winding 11 to the positive terminal of the second storage battery 32.

[0165] A first end of a common path 26 is connected to the neutral point of the armature winding 11. A first end of a first electrical path 27 is connected to a second end of the common path 26, and a second end of the first electrical path 27 is connected to a portion of the inter-battery electrical path 24 closer to the second storage battery 32 than the inter-battery switch 40. A first end of a second electrical path 28 is connected to the second end of the common path 26, and a second end of the second electrical path 28 is connected to a portion of the inter-battery electrical path 24 closer to the first storage battery 31 than the inter-battery switch 40. A first motor-side switch 60 is provided in the first electrical path 27. A second motor-side switch 61 is provided in the second electrical path 28. It is also possible to omit the common path 26 and have the first ends of the first electrical path 27 and the second electrical path 28 connected to the neutral point of the armature winding 11.

[0166] According to the present embodiment described above, the processing shown in FIG. 9 and the processing shown in FIG. 13 can be performed in the circuit configuration shown in FIG.

[0167] Tenth Embodiment A tenth embodiment will now be described with reference to the drawings, focusing on differences from the above-described embodiments. In this embodiment, as shown in Fig. 36 , a switch that connects the neutral point of the armature winding 11 to the negative terminal of the first storage battery 31 and a switch that connects the neutral point of the armature winding 11 to the positive terminal of the second storage battery 32 are provided as motor-side switches.

[0168] A first end of a common path 26 is connected to the neutral point of the armature winding 11. A first end of a first electrical path 27 is connected to a second end of the common path 26, and a second end of the first electrical path 27 is connected to a portion of the inter-battery electrical path 24 closer to the second storage battery 32 than the inter-battery switch 40. A first end of a second electrical path 28 is connected to the second end of the common path 26, and a second end of the second electrical path 28 is connected to a portion of the inter-battery electrical path 24 closer to the first storage battery 31 than the inter-battery switch 40. A first motor-side switch 60 is provided in the first electrical path 27. A second motor-side switch 61 is provided in the second electrical path 28. It is also possible to omit the common path 26 and have the first ends of the first electrical path 27 and the second electrical path 28 connected to the neutral point of the armature winding 11.

[0169] According to the present embodiment described above, the processing shown in FIG. 26 and the processing shown in FIG. 27 can be performed in the circuit configuration shown in FIG.

[0170] Other Embodiments The above-described embodiments may be modified as follows.

[0171] The motor is not limited to a star-connected motor, but may be a delta-connected motor. The motor and inverter are not limited to a three-phase motor, but may be a two-phase motor, or a four-phase or more phase motor. The motor is not limited to a permanent magnet synchronous machine having a permanent magnet as a field pole on the rotor, but may be a wound field synchronous machine having a field winding as a field pole on the rotor. In this case, the rotor may be provided with both a field winding and a permanent magnet. The motor is not limited to a synchronous machine, but may be an induction machine.

[0172] The switches of the inverter 20 are not limited to IGBTs with freewheel diodes connected in reverse parallel, but may be, for example, N-channel MOSFETs with body diodes. In this case, the high-potential terminal of the N-channel MOSFET serves as the drain, and the low-potential terminal serves as the source.

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

[0174] The power conversion device may be installed in a stationary device, not limited to a mobile object.

[0175] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0176] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; In a power conversion device comprising: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a bypass switch (50, 51) that performs at least one of an electrical connection between negative electrode terminals of the first power storage unit and the second power storage unit and an electrical connection between positive electrode terminals of the first power storage unit and the second power storage unit; a smoothing capacitor (21) electrically connecting the high potential side electrical path and the low potential side electrical path and smoothing an input voltage of the inverter; A voltage sensor (19) for detecting a voltage of the smoothing capacitor; a high potential side switch (SMRH) provided in the high potential side electrical path between a connection point with the upper arm switch and a connection point with a positive electrode terminal of the first storage unit; a low potential side switch (SMRL) provided in the low potential side electrical path between a connection point with the lower arm switch and a connection point with a negative electrode terminal of the second storage unit; a control unit (100) that determines whether or not one of the inter-storage unit switch and the bypass switch is fixed on before turning on the other switch, The control unit determines whether or not one of the inter-storage unit switch and the bypass switch is stuck 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.

2. the bypass switch is an inter-negative electrode bypass switch (50) that electrically connects a negative electrode terminal of the first power storage unit and a negative electrode terminal of the second power storage unit, The control unit is when it is determined that the voltage of the smoothing capacitor is equal to 0 V, it is determined that the inter-storage unit switch and the inter-negative electrode bypass switch are not stuck on, determining that the inter-power storage unit switch is stuck on 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; The power conversion device according to claim 1 , wherein, 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 stuck on.

3. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; In a power conversion device comprising: The motor has an armature winding (11), a connection point of the upper arm switch and the lower arm switch is electrically connected to a first end side of the armature winding; an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a bypass switch (50, 51) that performs at least one of an electrical connection between negative electrode terminals of the first power storage unit and the second power storage unit and an electrical connection between positive electrode terminals of the first power storage unit and the second power storage unit; a smoothing capacitor (21) electrically connecting the high potential side electrical path and the low potential side electrical path and smoothing an input voltage of the inverter; A voltage sensor (19) for detecting a voltage of the smoothing capacitor; a high potential side switch (SMRH) provided in the high potential side electrical path between a connection point with the upper arm switch and a connection point with a positive electrode terminal of the first storage unit; a motor-side electrical path (25) electrically connecting a second end side of the armature winding and the electrical path between the power storage unit; A motor-side switch (60) provided in the motor-side electrical path; a connection switch (80) provided on the motor side electrical path closer to the connection point than the motor side switch; a control unit (100) that determines whether or not one of the inter-storage unit switch and the bypass switch is fixed on before turning on the other switch, The control unit determines whether or not one of the inter-storage unit switch and the bypass switch is stuck on, based on the voltage of the smoothing capacitor detected by the voltage sensor when the high-side switch, the motor-side switch, and the connection switch are turned on.

4. the bypass switch is an inter-negative electrode bypass switch (50) that electrically connects a negative electrode terminal of the first power storage unit and a negative electrode terminal of the second power storage unit, the motor-side electrical path electrically connects a second end side of the armature winding and a portion of the inter-energy-storage-unit electrical path that is located on the second power storage unit side with respect to the inter-energy-storage-unit switch, The control unit is when it is determined that the voltage of the smoothing capacitor is equal to 0 V, it is determined that the inter-storage unit switch and the inter-negative electrode bypass switch are not stuck on, determining that the switch between the power storage units is stuck on when it is determined that the voltage of the smoothing capacitor is equal to the voltage of the first power storage unit; 4. The power conversion device according to claim 3, wherein when it is determined that the voltage of the smoothing capacitor is equal to a 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 stuck on.

5. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; In a power conversion device comprising: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a negative electrode bypass switch (50) that electrically connects a negative electrode terminal of the first power storage unit and a negative electrode terminal of the second power storage unit; a control unit (100) that determines whether or not one of the inter-storage unit switch and the negative electrode bypass switch is fixed on before turning on one of the switches, The control unit is determining that the inter-power storage unit switch and the negative electrode bypass switch are not stuck on when it is determined that the voltage across the inter-power storage unit switch is equal to the sum of the voltage of the first power storage unit and the voltage of the second power storage unit; when it is determined that the voltage across the power storage unit switch is equal to 0 V, it is determined that the power storage unit switch is stuck on; the power conversion device determines that the negative electrode bypass switch is stuck on when it is determined that the voltage across the power storage unit switch is equal to the voltage of the second power storage unit.

6. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; In a power conversion device comprising: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a negative electrode bypass switch (50) that electrically connects a negative electrode terminal of the first power storage unit and a negative electrode terminal of the second power storage unit; a control unit (100) that determines whether or not one of the inter-storage unit switch and the negative electrode bypass switch is fixed on before turning on one of the switches, The control unit is determining that the inter-power storage unit switch and the inter-negative pole bypass switch are not stuck on when it is determined that the voltage across the inter-negative pole bypass switch is equal to the voltage of the first power storage unit; determining that the switch between the power storage units is stuck on when it is determined that the voltage across the negative electrode bypass switch is equal to the voltage of the second power storage unit; When it is determined that the voltage across the negative pole bypass switch is equal to 0 V, it is determined that the negative pole bypass switch is stuck on.

7. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; In a power conversion device comprising: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a negative electrode bypass switch (50) that electrically connects a negative electrode terminal of the first power storage unit and a negative electrode terminal of the second power storage unit; a control unit (100) that determines whether or not one of the inter-storage unit switch and the negative electrode bypass switch is fixed on before turning on one of the switches, The control unit is determining that the inter-storage unit switch and the inter-negative electrode bypass switch are not stuck on when it is determined that the voltage between the positive electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit is equal to the voltage of the second power storage unit; determining that the inter-power storage unit switch is stuck 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 of the first power storage unit; a power conversion device that determines that the negative pole bypass switch is stuck on when it is determined that the voltage between the positive electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit is equal to a voltage difference between the voltage of the first storage unit and the voltage of the second storage unit.

8. the bypass switch is an inter-positive electrode bypass switch (51) that electrically connects a positive electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit, The control unit is when it is determined that the voltage of the smoothing capacitor is equal to 0 V, it is determined that the inter-storage unit switch and the inter-positive electrode bypass switch are not stuck on, determining that the inter-power storage unit switch is stuck on 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; The power conversion device according to claim 1 , wherein, 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 stuck on.

9. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; In a power conversion device comprising: The motor has an armature winding (11), a connection point of the upper arm switch and the lower arm switch is electrically connected to a first end side of the armature winding; an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a bypass switch (50, 51) that performs at least one of an electrical connection between negative electrode terminals of the first power storage unit and the second power storage unit and an electrical connection between positive electrode terminals of the first power storage unit and the second power storage unit; a smoothing capacitor (21) electrically connecting the high potential side electrical path and the low potential side electrical path and smoothing an input voltage of the inverter; A voltage sensor (19) for detecting a voltage of the smoothing capacitor; a low potential side switch (SMRL) provided in the low potential side electrical path between a connection point with the lower arm switch and a connection point with a negative electrode terminal of the second storage unit; a motor-side electrical path (25) electrically connecting a second end side of the armature winding and the electrical path between the power storage unit; A motor-side switch (61) provided in the motor-side electrical path; a connection switch (80) provided on the motor side electrical path closer to the connection point than the motor side switch; a control unit (100) that determines whether or not one of the inter-storage unit switch and the bypass switch is fixed on before turning on the other switch, The control unit determines whether or not one of the inter-storage unit switch and the bypass switch is stuck 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.

10. the bypass switch is an inter-positive electrode bypass switch (51) that electrically connects a positive electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit, the motor-side electrical path electrically connects a second end side of the armature winding and a portion of the inter-energy-storage-unit electrical path that is located on the first power storage unit side with respect to the inter-energy-storage-unit switch, The control unit is when it is determined that the voltage of the smoothing capacitor is equal to 0 V, it is determined that the inter-storage unit switch and the inter-positive electrode bypass switch are not stuck on, determining that the switch between the power storage units is stuck on when it is determined that the voltage of the smoothing capacitor is equal to the voltage of the second power storage unit; 10. The power conversion device according to claim 9, wherein, when it is determined that the voltage of the smoothing capacitor is equal to a 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 stuck on.

11. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; In a power conversion device comprising: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a positive electrode bypass switch (51) that electrically connects a positive electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit; a control unit (100) that determines whether or not one of the inter-storage unit switch and the inter-positive electrode bypass switch is stuck on before turning on the other switch, The control unit is determining that the inter-power storage unit switch and the positive electrode bypass switch are not stuck on when it is determined that the voltage across the inter-power storage unit switch is equal to the sum of the voltage of the first power storage unit and the voltage of the second power storage unit; when it is determined that the voltage across the power storage unit switch is equal to 0 V, it is determined that the power storage unit switch is stuck on; the power conversion device determines that the positive electrode bypass switch is stuck on when it is determined that the voltage across the inter-power storage unit switch is equal to the voltage of the first power storage unit.

12. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; In a power conversion device comprising: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a positive electrode bypass switch (51) that electrically connects a positive electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit; a control unit (100) that determines whether or not one of the inter-storage unit switch and the inter-positive electrode bypass switch is stuck on before turning on the other switch, The control unit is determining that the inter-power-storage-unit switch and the inter-positive-electrode bypass switch are not stuck on when it is determined that the voltage across the inter-positive-electrode bypass switch is equal to the voltage of the second power storage unit; determining that the switch between power storage units is stuck on when it is determined that the voltage across the positive electrode bypass switch is equal to the voltage of the first power storage unit; When it is determined that the voltage across the positive pole bypass switch is equal to 0 V, it is determined that the positive pole bypass switch is stuck on.

13. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; In a power conversion device comprising: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a positive electrode bypass switch (51) that electrically connects a positive electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit; a control unit (100) that determines whether or not one of the inter-storage unit switch and the inter-positive electrode bypass switch is stuck on before turning on the other switch, The control unit is determining that the inter-storage unit switch and the inter-positive electrode bypass switch are not stuck on when it is determined that the voltage between the negative electrode terminal of the first power storage unit and the negative electrode terminal of the second power storage unit is equal to the voltage of the first power storage unit; determining that the inter-power storage unit switch is stuck 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 of the second power storage unit; the power conversion device determines that the positive pole bypass switch is stuck on when it is determined that the voltage between the negative electrode terminal of the first power storage unit and the negative electrode terminal of the second power storage unit is equal to a voltage difference between the voltage of the second power storage unit and the voltage of the first power storage unit.

14. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; A program applied to a power conversion device including a computer (101), The power conversion device is an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a bypass switch (50, 51) that performs at least one of an electrical connection between negative electrode terminals of the first power storage unit and the second power storage unit and an electrical connection between positive electrode terminals of the first power storage unit and the second power storage unit; a smoothing capacitor (21) electrically connecting the high potential side electrical path and the low potential side electrical path and smoothing an input voltage of the inverter; A voltage sensor (19) for detecting a voltage of the smoothing capacitor; a high potential side switch (SMRH) provided in the high potential side electrical path between a connection point with the upper arm switch and a connection point with a positive electrode terminal of the first storage unit; a low potential side switch (SMRL) provided in the low potential side electrical path between a connection point with the lower arm switch and a connection point with a negative electrode terminal of the second storage unit; Equipped with The computer includes: executing a determination process for determining whether or not the other switch of the inter-storage unit switch and the bypass switch is stuck on before turning on one of the inter-storage unit switch and the bypass switch; a program for determining whether or not one of the inter-storage unit switch and the bypass switch is stuck on, based on a 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, in the determination process.

15. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; A program applied to a power conversion device including a computer (101), The motor has an armature winding (11), a connection point of the upper arm switch and the lower arm switch is electrically connected to a first end side of the armature winding; The power conversion device is an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a bypass switch (50, 51) that performs at least one of an electrical connection between negative electrode terminals of the first power storage unit and the second power storage unit and an electrical connection between positive electrode terminals of the first power storage unit and the second power storage unit; a smoothing capacitor (21) electrically connecting the high potential side electrical path and the low potential side electrical path and smoothing an input voltage of the inverter; A voltage sensor (19) for detecting a voltage of the smoothing capacitor; a high potential side switch (SMRH) provided in the high potential side electrical path between a connection point with the upper arm switch and a connection point with a positive electrode terminal of the first storage unit; a motor-side electrical path (25) electrically connecting a second end side of the armature winding and the electrical path between the power storage unit; A motor-side switch (60) provided in the motor-side electrical path; a connection switch (80) provided on the motor side electrical path closer to the connection point than the motor side switch; Equipped with The computer includes: executing a determination process for determining whether or not the other switch of the inter-storage unit switch and the bypass switch is stuck on before turning on one of the inter-storage unit switch and the bypass switch; a program for determining whether or not one of the switch between the power storage units and the bypass switch is stuck on, based on a 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, in the determination process.

16. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; A program applied to a power conversion device including a computer (101), The power conversion device is an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a negative electrode bypass switch (50) that electrically connects a negative electrode terminal of the first power storage unit and a negative electrode terminal of the second power storage unit; Equipped with The computer includes: executing a determination process for determining whether or not the other of the inter-storage unit switch and the inter-negative electrode bypass switch is stuck on before turning on one of the inter-storage unit switch and the inter-negative electrode bypass switch; In the determination process, determining that the inter-power storage unit switch and the negative electrode bypass switch are not stuck on when it is determined that the voltage across the inter-power storage unit switch is equal to the sum of the voltage of the first power storage unit and the voltage of the second power storage unit; when it is determined that the voltage across the power storage unit switch is equal to 0 V, it is determined that the power storage unit switch is stuck on; the program determining that the negative electrode bypass switch is stuck on when it is determined that the voltage across the power storage unit switch is equal to the voltage of the second power storage unit.

17. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; A program applied to a power conversion device including a computer (101), The power conversion device is an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a negative electrode bypass switch (50) that electrically connects a negative electrode terminal of the first power storage unit and a negative electrode terminal of the second power storage unit; Equipped with The computer includes: executing a determination process for determining whether or not the other of the inter-storage unit switch and the inter-negative electrode bypass switch is stuck on before turning on one of the inter-storage unit switch and the inter-negative electrode bypass switch; In the determination process, determining that the inter-power storage unit switch and the inter-negative pole bypass switch are not stuck on when it is determined that the voltage across the inter-negative pole bypass switch is equal to the voltage of the first power storage unit; determining that the switch between the power storage units is stuck on when it is determined that the voltage across the negative electrode bypass switch is equal to the voltage of the second power storage unit; the program determining that the negative electrode bypass switch is stuck on when it is determined that the voltage across the negative electrode bypass switch is equal to 0 V.

18. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; A program applied to a power conversion device including a computer (101), The power conversion device is an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a negative electrode bypass switch (50) that electrically connects a negative electrode terminal of the first power storage unit and a negative electrode terminal of the second power storage unit; Equipped with The computer includes: executing a determination process for determining whether or not the other of the inter-storage unit switch and the inter-negative electrode bypass switch is stuck on before turning on one of the inter-storage unit switch and the inter-negative electrode bypass switch; In the determination process, determining that the inter-storage unit switch and the inter-negative electrode bypass switch are not stuck on when it is determined that the voltage between the positive electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit is equal to the voltage of the second power storage unit; determining that the inter-power storage unit switch is stuck 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 of the first power storage unit; a program for determining that the negative pole bypass switch is stuck on when it is determined that the voltage between the positive electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit is equal to a voltage difference between the voltage of the first power storage unit and the voltage of the second power storage unit.

19. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; A program applied to a power conversion device including a computer (101), The motor has an armature winding (11), a connection point of the upper arm switch and the lower arm switch is electrically connected to a first end side of the armature winding; The power conversion device is an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a bypass switch (50, 51) that performs at least one of an electrical connection between negative electrode terminals of the first power storage unit and the second power storage unit and an electrical connection between positive electrode terminals of the first power storage unit and the second power storage unit; a smoothing capacitor (21) electrically connecting the high potential side electrical path and the low potential side electrical path and smoothing an input voltage of the inverter; A voltage sensor (19) for detecting a voltage of the smoothing capacitor; a low potential side switch (SMRL) provided in the low potential side electrical path between a connection point with the lower arm switch and a connection point with a negative electrode terminal of the second storage unit; a motor-side electrical path (25) electrically connecting a second end side of the armature winding and the electrical path between the power storage unit; A motor-side switch (61) provided in the motor-side electrical path; a connection switch (80) provided on the motor side electrical path closer to the connection point than the motor side switch; Equipped with The computer includes: executing a determination process for determining whether or not the other switch of the inter-storage unit switch and the bypass switch is stuck on before turning on one of the inter-storage unit switch and the bypass switch; a program for determining whether or not one of the switch between the power storage units and the bypass switch is stuck 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, in the determination process.

20. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; A program applied to a power conversion device including a computer (101), The power conversion device is an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a positive electrode bypass switch (51) that electrically connects a positive electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit; Equipped with The computer includes: executing a determination process for determining whether or not the other switch of the inter-storage unit switch and the inter-positive electrode bypass switch is stuck on before turning on one of the inter-storage unit switch and the inter-positive electrode bypass switch; In the determination process, determining that the inter-power storage unit switch and the positive electrode bypass switch are not stuck on when it is determined that the voltage across the inter-power storage unit switch is equal to the sum of the voltage of the first power storage unit and the voltage of the second power storage unit; when it is determined that the voltage across the power storage unit switch is equal to 0 V, it is determined that the power storage unit switch is stuck on; the program determining that the positive electrode bypass switch is stuck on when it is determined that the voltage across the power storage unit switch is equal to the voltage of the first power storage unit.

21. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; A program applied to a power conversion device including a computer (101), The power conversion device is an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a positive electrode bypass switch (51) that electrically connects a positive electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit; Equipped with The computer includes: executing a determination process for determining whether or not the other switch of the inter-storage unit switch and the inter-positive electrode bypass switch is stuck on before turning on one of the inter-storage unit switch and the inter-positive electrode bypass switch; In the determination process, determining that the inter-power-storage-unit switch and the inter-positive-electrode bypass switch are not stuck on when it is determined that the voltage across the inter-positive-electrode bypass switch is equal to the voltage of the second power storage unit; determining that the switch between power storage units is stuck on when it is determined that the voltage across the positive electrode bypass switch is equal to the voltage of the first power storage unit; a program for determining that the positive pole-to-positive pole bypass switch is stuck on when the voltage across the positive pole-to-positive pole bypass switch is determined to be equal to 0 V;

22. a high potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second 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; a motor (10) electrically connected to a connection point of the upper arm switch and the lower arm switch; A program applied to a power conversion device including a computer (101), The power conversion device is an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a positive electrode bypass switch (51) that electrically connects a positive electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit; Equipped with The computer includes: executing a determination process for determining whether or not the other switch of the inter-storage unit switch and the inter-positive electrode bypass switch is stuck on before turning on one of the inter-storage unit switch and the inter-positive electrode bypass switch; In the determination process, determining that the inter-storage unit switch and the inter-positive electrode bypass switch are not stuck on when it is determined that the voltage between the negative electrode terminal of the first power storage unit and the negative electrode terminal of the second power storage unit is equal to the voltage of the first power storage unit; determining that the inter-power storage unit switch is stuck 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 of the second power storage unit; a program for determining that the positive electrode bypass switch is stuck on when it is determined that the voltage between the negative electrode terminal of the first power storage unit and the negative electrode terminal of the second power storage unit is equal to a voltage difference between the voltage of the second power storage unit and the voltage of the first power storage unit.