Electric power conversion apparatus

Abstract

This electric power conversion apparatus comprises a connection path (73), first restriction units (61, 62, 161, 162), and second restriction units (SMRH, DA, DB). One of the first and second restriction units has a function for restricting the flow of an electric current in a specific direction from a high-potential-side path (22H) side toward the first-restriction-unit side, and allowing the flow of an electric current in a direction opposite from the specific direction. The other of the first and second restriction units is a restriction switch (SMRH, 62, 162) that is turned on or off. The electric power conversion apparatus comprises control devices (90, 100) that, when an external electric power supply target unit (230) is electrically connected to the high-potential-side path and a low-potential-side path (22L), perform switching control for an inverter (20) in a state in which an inter-electric-power-storage-unit switch (50) is turned off and the restriction switch is turned on, thereby channeling an electric current through a closed circuit that includes the external electric power supply target unit, the connection path, an armature winding (11), and the inverter to supply electric power to the external electric power supply target unit.

Description

Power Conversion Device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2024-025867, filed on February 22, 2024, the contents of which are incorporated herein by reference.

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

[0003] A power conversion device has been known that is applied to a system including first and second power storage units, and that includes an inverter supplied with power from the first and second power storage units, and a motor having an armature winding electrically connected to the inverter. An example of such a power conversion device is described in Patent Document 1.

[0004] Japanese Patent Application Laid-Open No. 2022-22891

[0005] There is a concern that an overcurrent may flow in the power conversion device due to some factor.

[0006] A primary object of the present disclosure is to provide a power conversion device that can suppress the occurrence of situations in which an overcurrent flows.

[0007] The present disclosure relates to a power conversion device including: a multi-phase inverter having upper and lower arm switches, and upper and lower arm diodes connected in anti-parallel to the upper and lower arm switches; and a motor having an armature winding electrically connected to a low potential side terminal of the upper arm switches of each phase and a high potential side terminal of the lower arm switches of each phase, the power conversion device comprising: an inter-storage unit switch that, when turned on, electrically connects a negative terminal of a first power storage unit and a positive terminal of a second power storage unit, and, when turned off, electrically disconnects the negative terminal of the first power storage unit and the positive terminal of the second power storage unit; a high potential side path electrically connected to the high potential side terminal of the upper arm switches of each phase; a low potential side path electrically connecting a low potential side terminal of the lower arm switches of each phase and the negative terminal of the second power storage unit; and a connection path electrically connecting the positive terminal of the second power storage unit or the negative terminal of the first power storage unit to the armature winding. the control device comprises: a first regulating unit that electrically connects either a positive terminal or a negative terminal of each of the first power storage unit and the second power storage unit; and a second regulating unit that electrically connects the high potential side path and the positive terminal of the first power storage unit; one of the first regulating unit and the second regulating unit has a function of regulating a flow of current in a specific direction from the high potential side path to the first regulating unit and allowing a flow of current in a direction opposite to the specific direction, and the other is a regulating switch that is turned on or off; and a control device that performs external power supply control to supply power to the external power supply target unit by controlling switching of a target switch that is at least one of the upper and lower arm switches when the inter-power storage unit switch is turned off and the regulating switch is turned on, when an external power supply target unit is electrically connected to the high potential side path and the low potential side path.

[0008] In the present disclosure, the control device performs external power supply control, which is switching control of a target switch. Here, when the external power supply control is performed, if the potential difference between the first and second power storage units is large, there is a concern that an overcurrent will flow from one of the first and second power storage units to the other via the inverter.

[0009] Therefore, one of the first and second restricting units in the present disclosure has a function of restricting the flow of current in a specific direction from the high-potential side path to the first restricting unit, and allowing the flow of current in the direction opposite to the specific direction, thereby making it possible to suppress the occurrence of a situation in which an overcurrent flows in the power conversion device.

[0010] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is an overall configuration diagram of a system according to a first embodiment, Fig. 2 is a diagram showing the control state of switches during high-voltage charging, Fig. 3 is a diagram showing the control state of switches during low-voltage charging, Fig. 4 is a diagram showing the control state of switches during high-voltage charging, Fig. 5 is a diagram showing the control state of switches during low-voltage charging, Fig. 6 is an overall configuration diagram of a system according to a second embodiment, Fig. 7 is an overall configuration diagram of a system according to a third embodiment, Fig. 8 is a flowchart showing the processing procedure during external charging and power supply control, Fig. 9 is an overall configuration diagram of a system according to a fourth embodiment, Fig. 10 is a flowchart showing the processing procedure during external charging and power supply control, and Fig. 11 is a flowchart showing the processing procedure during external charging and power supply control. 12 is a diagram showing the control state of the switches during high-voltage charging, FIG. 13 is a diagram showing the control state of the switches during low-voltage charging, FIG. 14 is a diagram showing the control state of the switches during high-voltage charging, FIG. 15 is a diagram showing the control state of the switches during low-voltage charging, FIG. 16 is a diagram showing the overall configuration of the system according to the sixth embodiment, FIG. 17 is a diagram showing the overall configuration of the system according to the seventh embodiment, FIG. 18 is a diagram showing the overall configuration of the system according to the eighth embodiment, FIG. 19 is a diagram showing the configuration of the first regulating unit and the parallel switch according to other embodiments, and FIG. 20 is a diagram showing the configuration of the first regulating unit and the parallel switch according to other embodiments.

[0011] 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.

[0012] 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 mounted on a vehicle such as an electric vehicle or a hybrid vehicle, and forms an in-vehicle system.

[0013] As shown in FIG. 1 , the power conversion device includes a motor 10, an inverter 20, a high-potential side path 22H, and a low-potential side path 22L. The motor 10 is a three-phase synchronous machine that 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.

[0014] 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.

[0015] The inverter 20 includes a smoothing capacitor 21. A high-potential side path 22H is connected to a high-potential side terminal of the smoothing capacitor 21. A low-potential side path 22L is connected to a low-potential side terminal of the smoothing capacitor 21. The high-potential side path 22H and the low-potential side path 22L are, for example, electrical paths such as bus bars. The smoothing capacitor 21 may be provided outside the inverter 20.

[0016] In each phase, a high-potential-side path 22H is connected to the collector, which is the high-potential-side terminal of the upper switch SWH, and a low-potential-side path 22L is connected to the emitter, which is the low-potential-side terminal of the lower switch SWL. In each phase, a first end of the armature winding 11 is connected to the connection point between the emitter of the upper switch SWH and the collector of the lower 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 O. 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.

[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 an assembled battery including a series connection of multiple unit batteries. A unit battery is a single battery cell, which is a single cell, or a series connection of multiple battery cells. In this embodiment, the unit batteries constituting the first storage battery 31 and the second storage battery 32 have the same full charge capacity (specifically, for example, rated full charge capacity) [Ah]. The terminal voltages (e.g., rated voltages) of the battery cells constituting the assembled battery are set to be the same, for example. The battery cells are secondary batteries such as lithium-ion batteries. In this embodiment, the terminal voltage (e.g., rated voltage) of the first storage battery 31 and the terminal voltage (e.g., rated voltage) of the second storage battery 32 are the same. This configuration can be realized, for example, by making the number of unit batteries constituting the first storage battery 31 the same as the number of unit batteries constituting the second storage battery 32 .

[0018] The power conversion device includes main switches for electrically connecting or disconnecting the first and second storage batteries 31, 32 and the inverter 20. Specifically, the main switches include a high-side main switch SMRH, a low-side main switch SMRL, and a pre-charge main switch SMRP. In this embodiment, the main switches SMRH, SMRL, and SMRP are mechanical relays. When turned off, each of the main switches SMRH, SMRL, and SMRP blocks bidirectional current flow, and when turned on, allows bidirectional current flow.

[0019] The positive terminal of the first storage battery 31 is connected to the high-potential-side path 22H via a first fuse 41 and a high-potential-side main switch SMRH. The negative terminal of the second storage battery 32 is connected to the low-potential-side path 22L via a second fuse 42 and a low-potential-side main switch SMRL. A series connection of a pre-charge main switch SMRP and a pre-charge resistor 40 is connected in parallel to the low-potential-side main switch SMRL. Note that each of the main switches SMRH, SMRL, and SMRP is not limited to a mechanical relay, and may be, for example, a semiconductor switching element.

[0020] Each of the storage batteries 31 and 32 can be charged by an external charger provided outside the vehicle through external charging control. The external charger is, for example, a stationary charger.

[0021] Each of the storage batteries 31, 32 can supply power to a power supply target outside the vehicle through external power supply control. When the power supply target is a grid power supply, the external power supply control is also called V2G (Vehicle to Grid). When the power supply target is an electrical device in a building such as a residence, the external power supply control is also called V2H (Vehicle to Home).

[0022] The power conversion device includes a high-potential-side connection switch DCRH and a low-potential-side connection switch DCRL for electrically connecting or disconnecting an external charger or a power supply target unit to or from the first and second storage batteries 31, 32. In this embodiment, each of the connection switches DCRH and DCRL is a mechanical relay. When turned off, each of the connection switches DCRH and DCRL blocks bidirectional current flow, and when turned on, each of the connection switches DCRH and DCRL allows bidirectional current flow. The high-potential-side connection switch DCRH is connected to the high-potential-side path 22H, and the low-potential-side connection switch DCRL is connected to the low-potential-side path 22L. Note that each of the connection switches DCRH and DCRL is not limited to a mechanical relay, and may be, for example, a semiconductor switching element.

[0023] The power conversion device includes an inter-battery switch 50 (corresponding to an "inter-energy storage unit switch"), a parallel switch 60, a first motor-side switch 71, a second motor-side switch 72, and a connection path 73 as components for switching the connection state of the first storage battery 31 and the second storage battery 32. In this embodiment, the inter-battery switch 50 and each of the motor-side switches 71, 72 are mechanical relays. When turned off, the inter-battery switch 50 and each of the motor-side switches 71, 72 block bidirectional current flow, and when turned on, allow bidirectional current flow. Note that the inter-battery switch 50 and each of the motor-side switches 71, 72 are not limited to mechanical relays and may be, for example, semiconductor switching elements.

[0024] The inter-battery switch 50 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 50 is turned on, the negative terminal of the first storage battery 31 and the positive terminal of the second storage battery 32 are electrically connected. When the inter-battery switch 50 is turned off, the negative terminal of the first storage battery 31 and the positive terminal of the second storage battery 32 are electrically disconnected.

[0025] In this embodiment, the parallel switch 60 is a voltage-controlled semiconductor switching element, specifically an IGBT. The collector of the parallel switch 60 is connected to the negative terminal of the first storage battery 31, and the emitter of the parallel switch 60 is connected to the negative terminal of the second storage battery 32 via a second fuse 42. When the parallel switch 60 is turned on, current is allowed to flow from the collector to the emitter of the parallel switch 60. Current is also allowed to flow from the emitter to the collector of the parallel switch 60 via a regulating diode 61, which will be described later. On the other hand, when the parallel switch 60 is turned off, the negative terminal of the first storage battery 31 and the negative terminal of the second storage battery 32 are electrically disconnected. In this embodiment, the first storage battery 31 and the second storage battery 32 constitute a battery unit 30.

[0026] The parallel switch 60 is not limited to an IGBT, and may be, for example, an N-channel MOSFET equipped with a body diode. The high-potential terminal of the N-channel MOSFET serves as the drain, and the low-potential terminal serves as the source. In this case, the source of the parallel switch, which is an N-channel MOSFET, is electrically connected to the negative terminal of the second storage battery 32, and the drain of the parallel switch is electrically connected to the negative terminal of the first storage battery 31. The body diode of the parallel switch serves as a regulating diode 61, which will be described later.

[0027] The connection path 73 is an electrical path that connects the positive terminal of the second storage battery 32 and the neutral point O. The connection path 73 is provided with a first motor-side switch 71 and a second motor-side switch 72 in this order from the second storage battery 32.

[0028] The power conversion device includes a neutral point capacitor 74 that connects the connection path 73 and the low potential side path 22L. A first end of the neutral point capacitor 74 is connected to a portion of the connection path 73 between the first motor side switch 71 and the second motor side switch 72. A second end of the neutral point capacitor 74 is connected to the low potential side path 22L.

[0029] When the first motor-side switch 71 is turned on, the first end of the neutral point capacitor 74 is electrically connected to the positive terminal of the second storage battery 32. On the other hand, when the first motor-side switch 71 is turned off, the first end of the neutral point capacitor 74 is electrically disconnected from the positive terminal of the second storage battery 32. When the second motor-side switch 72 is turned on, the neutral point O of the armature winding 11 is electrically connected to the first end of the neutral point capacitor 74. On the other hand, when the second motor-side switch 72 is turned off, the neutral point O is electrically disconnected from the first end of the neutral point capacitor 74.

[0030] The power conversion device includes current sensors that detect the current flowing through each part of the power conversion device itself, including a first current sensor 81, a second current sensor 82, a phase current sensor 83, and a motor current sensor 84. The first current sensor 81 detects the current flowing through the first storage battery 31, and the second current sensor 82 detects the current flowing through the second storage battery 32. The phase current sensor 83 detects the current flowing through the armature winding 11 of each phase. The motor current sensor 84 detects the current flowing through the connection path 73, and in this embodiment, detects the current flowing through a portion of the connection path 73 that is closer to the neutral point O than the connection point with the neutral point capacitor 74.

[0031] The power conversion device includes a capacitor voltage sensor 85 that detects the terminal voltage of the neutral point capacitor 74, a first voltage sensor 86 that detects the terminal voltage of the first storage battery 31, and a second voltage sensor 87 that detects the terminal voltage of the second storage battery 32. The first voltage sensor 86 detects, for example, the terminal voltage of each unit battery that constitutes the first storage battery 31, and the second voltage sensor 87 detects, for example, the terminal voltage of each unit battery that constitutes the second storage battery 32. The power conversion device also includes a power supply voltage sensor 89 that detects the terminal voltage of the smoothing capacitor 21. The power conversion device also includes, as another sensor, a rotation angle sensor (not shown) that detects the rotation angle (electrical angle) of the rotor.

[0032] The system includes a battery ECU 90 that controls the battery unit 30, and an EVECU 100 that controls the inverter 20. The battery ECU 90 is an electronic control unit that mainly comprises a microcomputer 91. The EVECU 100 is an electronic control unit that mainly comprises a microcomputer 101. The battery ECU 90 and the EVECU 100 can exchange information via a communication unit such as CAN communication.

[0033] Each microcomputer 91, 101 includes a central processing unit (CPU). The functions of each microcomputer 91, 101 can be provided by software stored in a physical memory device and a computer executing the software, software alone, hardware alone, or a combination thereof. For example, when each microcomputer 91, 101 is provided by a hardware electronic circuit, the function can be provided by a digital circuit including multiple logic circuits or an analog circuit. For example, each microcomputer 91, 101 executes a program stored in a non-transitory tangible storage medium serving as its own storage unit. The program includes, for example, a program for external charging and power supply control. A set of instructions constituting the program is executed to perform a method corresponding to the program. The storage unit is, for example, a non-volatile memory. The program stored in the storage unit can be updated via a communication network such as the Internet, for example, via OTA (Over the Air).

[0034] The battery ECU 90 receives detection values ​​from the first current sensor 81, the second current sensor 82, the first voltage sensor 86, and the second voltage sensor 87. The battery ECU 90 calculates the SOC of each unit battery that constitutes the first storage battery 31 based on the detection values ​​of the first voltage sensor 86 and the first current sensor 81. The battery ECU 90 calculates the SOC of each unit battery that constitutes the second storage battery 32 based on the detection values ​​of the second voltage sensor 87 and the second current sensor 82.

[0035] The EVECU 100 receives detection values ​​from a phase current sensor 83, a motor current sensor 84, a capacitor voltage sensor 85, a power supply voltage sensor 89, and a rotation angle sensor. Based on the detection values ​​received from each sensor, the EVECU 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. 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. As a result, the rotational power of the rotor of the motor 10 is transmitted to the drive wheels, causing the vehicle to run.

[0036] The main switches SMRH, SMRL, SMRP, the connection switches DCRH, DCRL, the inter-battery switch 50, the parallel switch 60, and the motor-side switches 71, 72 may be controlled by either the battery ECU 90 or the EVECU 100. In this embodiment, for convenience, it is assumed that the main switches SMRH, SMRL, SMRP, the connection switches DCRH, DCRL, the inter-battery switch 50, the parallel switch 60, the first motor-side switch 71, and the second motor-side switch 72 are controlled by the EVECU 100.

[0037] The power conversion device includes a regulating diode 61. The regulating diode 61 is an element for suppressing an overcurrent (e.g., an inrush current) from flowing from the second storage battery 32 to the first storage battery 31 via the connection path 73, the armature winding 11, and the upper-arm diode DH when external power supply control is performed while the inter-terminal voltage of the second storage battery 32 relative to the first storage battery 31 is high. The anode of the regulating diode 61 is connected to the emitter of the parallel switch 60, and the cathode of the regulating diode 61 is connected to the collector of the parallel switch 60. As a result, the regulating diode 61 regulates (e.g., blocks) the flow of current in a specific direction from the high-potential-side path 22H to the regulating diode 61 via the first storage battery 31, and allows the flow of current in a direction opposite to the specific direction. In this embodiment, the regulating diode 61 corresponds to a “first regulating unit,” and the high-potential-side main switch SMRH corresponds to a “second regulating unit.”

[0038] Next, the external charging control will be described.

[0039] In this embodiment, the external charger is a high-voltage charger 200 or a low-voltage charger 210, as shown in FIGS. 2 and 3 . The charging voltage of the high-voltage charger 200 is higher than the inter-terminal voltage (specifically, the rated voltage) of the series-connected first and second storage batteries 31, 32, e.g., 800 V. The charging voltage of the low-voltage charger 210 is lower than the inter-terminal voltage of the series-connected first and second storage batteries 31, 32 and higher than the inter-terminal voltage (specifically, the rated voltage) of the first storage battery 31, e.g., 400 V. When the first and second storage batteries 31, 32 are being charged by the external charger, the high-potential-side connection switch DCRH and the low-potential-side connection switch DCRL are switched on. On the other hand, when charging by the external charger is not being performed or the external charger is not connected to the power conversion device, the high-potential-side connection switch DCRH and the low-potential-side connection switch DCRL are switched off.

[0040] 2 shows the control state of each switch during external charging control using the high-voltage charger 200. The vehicle user electrically connects the charging plug of the high-voltage charger 200 to the connection switches DCRH and DCRL, thereby electrically connecting the high-voltage charger 200 to the power conversion device. When the EVECU 100 determines that the external charger connected to the power conversion device is the high-voltage charger 200, it turns off the pre-charge main switch SMRP, the parallel switch 60, the first motor-side switch 71, the second motor-side switch 72, and the upper and lower arm switches SWH and SWL of all phases of the inverter 20, and turns on the high-potential-side main switch SMRH, the low-potential-side main switch SMRL, and the inter-battery switch 50. This results in the first storage battery 31 and the second storage battery 32 being connected in series to the high-voltage charger 200. As a result, current flows through a closed circuit including the high-voltage charger 200, the high-potential side path 22H, the first storage battery 31, the inter-battery switch 50, the second storage battery 32, and the low-potential side 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 of the inverter 20 and the second motor-side switch 72 are turned off, it is possible to prevent the charging current of the high-voltage charger 200 from flowing to the inverter 20 and the armature winding 11.

[0041] 3 shows the control states of each switch during external charging control using the low-voltage charger 210. When the vehicle user electrically connects the charging plug of the low-voltage charger 210 to the connection switches DCRH and DCRL, the low-voltage charger 210 is electrically connected to the power conversion device. When the EVECU 100 determines that the external charger connected to the power conversion device is the low-voltage charger 210, it turns off the pre-charge main switch SMRP and the inter-battery switch 50 and turns on the high-side main switch SMRH, the low-side main switch SMRL, the parallel switch 60, the first motor-side switch 71, and the second motor-side switch 72. As a result, current flows through a closed circuit including the low-voltage charger 210, the high-side path 22H, the first storage battery 31, the parallel switch 60, and the low-side path 22L, thereby charging the first storage battery 31. The parallel switch 60, which is turned on, forms a closed circuit including the low-voltage charger 210 and the first storage battery 31.

[0042] In the external charging control by the low-voltage charger 210, the EVECU 100 performs switching control to alternately turn on the upper and lower arm switches SWH, SWL of at least one phase, or performs switching control to switch on the upper arm switch SWH of at least one phase while keeping the lower arm switches SWL of all phases of the inverter 20 off, thereby stepping down the output voltage of the low-voltage charger 210 and supplying it to the second storage battery 32. More specifically, the EVECU 100 performs step-down control, which is the switching control described above, to control the voltage detected by the capacitor voltage sensor 85 (hereinafter referred to as the neutral point capacitor voltage VN) to a target charging voltage. As a result, a current flows through a closed circuit including the low-voltage charger 210, the high-potential side path 22H, the upper arm switch SWH of the inverter 20, the armature winding 11, the neutral point O, the second motor-side switch 72, the first motor-side switch 71, the second storage battery 32, and the low-potential side path 22L, and the second storage battery 32 is charged. Since the terminal voltage of the second storage battery 32 is lower than the terminal voltage of the first storage battery 31, the target charging voltage of the second storage battery 32 is lower than the target charging voltage of the first storage battery 31. In this embodiment, the upper arm switch SWH corresponds to the "target switch."

[0043] Next, the external power supply control will be described.

[0044] 4 shows the control state of each switch during external power supply control in which power is supplied from the first and second storage batteries 31, 32 to the high-voltage power supply target 220. When the EVECU 100 determines that the power supply target connected to the power conversion device is the high-voltage power supply target 220, it turns off the pre-charge main switch SMRP, the parallel switch 60, the first motor-side switch 71, the second motor-side switch 72, and the upper and lower arm switches SWH, SWL of all phases of the inverter 20, and turns on the connection switches DCRH, DCRL, the high-potential-side main switch SMRH, the low-potential-side main switch SMRL, and the inter-battery switch 50. This results in the first storage battery 31 and the second storage battery 32 being connected in series to the high-voltage power supply target 220. Therefore, current flows through a closed circuit including the first storage battery 31, the high-voltage side path 22H, the high-voltage power supply target portion 220, the low-voltage side path 22L, and the second storage battery 32, and power is supplied from the first storage battery 31 and the second storage battery 32 to the high-voltage power supply target portion 220.

[0045] 5 shows the control states of each switch during external power supply control in which power is supplied from the first and second storage batteries 31, 32 to the low-voltage power supply target unit 230. The rated voltage of the low-voltage power supply target unit 230 is lower than the rated voltage of the high-voltage power supply target unit 220. When the EVECU 100 determines that the power supply target unit connected to the power conversion device is the low-voltage power supply target unit 230, it turns off the pre-charge main switch SMRP and the inter-battery switch 50 and turns on the connection switches DCRH, DCRL, the high-potential-side main switch SMRH, the low-potential-side main switch SMRL, the parallel switch 60, the first motor-side switch 71, and the second motor-side switch 72. As a result, current flows through a closed circuit including the first storage battery 31, the high-potential-side path 22H, the low-voltage power supply target unit 230, the low-potential-side path 22L, and the parallel switch 60, and power is supplied from the first storage battery 31 to the low-voltage power supply target unit 230.

[0046] In the external power supply control for the low-voltage power supply target 230, the EVECU 100 performs switching control to alternately turn on the upper and lower arm switches SWH and SWL of at least one phase, or performs switching control to turn on the lower arm switch SWL of at least one phase while keeping the upper arm switches SWH of all phases of the inverter 20 off, thereby boosting the output voltage of the second storage battery 32 and supplying it to the low-voltage power supply target 230. Specifically, the EVECU 100 performs boost control, which is the switching control for controlling the power supply voltage VB, which is the voltage detected by the power supply voltage sensor 89, to a target power supply voltage. As a result, current flows through a closed circuit including the second storage battery 32, the connection path 73, the armature winding 11, the inverter 20, the high-potential-side path 22H, the low-voltage power supply target 230, and the low-potential-side path 22L, and power is supplied from the second storage battery 32 to the low-voltage power supply target 230. In this embodiment, the lower arm switch SWL corresponds to the "target switch."

[0047] The external power supply control may be started in a state in which the inter-terminal voltage of the second storage battery 32 is higher than that of the first storage battery 31. In this case, when a switch such as the high-potential side main switch SMRH is turned on during the external power supply control, there is a concern that an overcurrent may flow from the second storage battery 32 to the first storage battery 31 via the connection path 73, the armature winding 11, the upper-arm diode DH, and the high-potential side path 22H. In this case, for example, each of the main switches SMRH and SMRL may fail (e.g., be welded).

[0048] In this embodiment, the regulating diode 61 is provided. Therefore, even if the inter-terminal voltage of the second storage battery 32 is higher than that of the first storage battery 31, it is possible to suppress the occurrence of a situation in which an overcurrent flows from the second storage battery 32 to the first storage battery 31 via the connection path 73, the armature winding 11, the upper arm diode DH, and the high-potential side path 22H.

[0049] When the terminal voltage of the second storage battery 32 is higher than the terminal voltage of the first storage battery 31 , power is supplied to the low-voltage power supply target unit 230 from the second storage battery 32 of the first and second storage batteries 31 , 32 .

[0050] While supplying power from the second storage battery 32 to the low-voltage power supply target unit 230, the EVECU 100 controls the switching of the inverter 20 so that the terminal voltage of the second storage battery 32 detected by the second voltage sensor 87 approaches the terminal voltage of the first storage battery 31 detected by the first voltage sensor 86. As a result, when the terminal voltage of the second storage battery 32 drops and reaches the terminal voltage of the first storage battery 31, power starts to be supplied from the first storage battery 31 to the low-voltage power supply target unit 230. In this way, as the terminal voltage of the second storage battery 32 drops, power supply from the first storage battery 31 to the low-voltage power supply target unit 230 can be started.

[0051] Second Embodiment A second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in FIG. 6, the installation positions of the regulating diode and the regulating switch are changed.

[0052] The power conversion device includes a regulating switch 62, a regulating diode DA, and a parallel switch SMRA. The regulating switch 62 electrically connects the negative terminal of the first storage battery 31 and the negative terminal of the second storage battery 32. In this embodiment, the regulating switch 62 is a mechanical relay. When the regulating switch 62 is turned off, it blocks bidirectional current flow, and when turned on, it allows bidirectional current flow. The regulating switch 62 is not limited to a mechanical relay, and may be a semiconductor switching element such as an IGBT or an N-channel MOSFET.

[0053] The parallel switch SMRA connects the high-potential-side path 22H and the first fuse 41. In this embodiment, the parallel switch SMRA is a voltage-controlled semiconductor switching element, specifically an IGBT. The high-potential-side path 22H is connected to the collector of the parallel switch SMRA, and the positive terminal of the first storage battery 31 is connected to the emitter of the parallel switch SMRA via the first fuse 41. When the parallel switch SMRA is turned on, current is allowed to flow only from the collector to the emitter of the parallel switch SMRA. On the other hand, when the parallel switch SMRA is turned off, the positive terminal of the first storage battery 31 is electrically disconnected from the high-potential-side path 22H. Note that the parallel switch SMRA is not limited to an IGBT, and may be, for example, an N-channel MOSFET including a body diode.

[0054] Similar to the regulating diode 61 of the first embodiment, the regulating diode DA is an element for preventing a large current from flowing from the second storage battery 32 to the first storage battery 31 via the connection path 73, the armature winding 11, and the upper arm diode DH when external power supply control is performed in a state where the voltage difference between the second storage battery 32 and the first storage battery 31 is large.

[0055] The anode of the regulating diode DA is connected to the emitter of the parallel switch SMRA, and the cathode of the regulating diode DA is connected to the collector of the parallel switch SMRA. This allows the regulating diode DA to regulate (e.g., block) current flow in a specific direction from the high-potential-side path 22H toward the regulating diode DA, while allowing current flow in the opposite direction. In this embodiment, the regulating diode DA corresponds to a "second regulating unit," and the regulating switch 62 corresponds to a "first regulating unit."

[0056] In this embodiment, during external charging control using the high-voltage charger 200, the regulating switch 62 is turned off instead of the parallel switch 60 in the first embodiment, and the parallel switch SMRA is turned on instead of the high-potential side main switch SMRH in the first embodiment. Furthermore, during external charging control using the low-voltage charger 210, the parallel switch SMRA is turned on instead of the high-potential side main switch SMRH in the first embodiment.

[0057] During external power feeding control for feeding power to the high-voltage power feed target unit 220, the regulating switch 62 is turned off instead of the parallel switch 60 of the first embodiment, and the parallel switch SMRA is turned on instead of the high-potential side main switch SMRH of the first embodiment. Moreover, during external power feeding control for feeding power to the low-voltage power feed target unit 230, the parallel switch SMRA is turned on instead of the high-potential side main switch SMRH of the first embodiment, and the regulating switch 62 is turned off instead of the parallel switch 60 of the first embodiment.

[0058] According to the present embodiment described above, it is possible to achieve the same effects as the first embodiment.

[0059] Third Embodiment A third embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in FIG. 7 , the power conversion device includes a bypass switch 63. The bypass switch 63 electrically connects the negative terminal of the first storage battery 31 and the negative terminal of the second storage battery 32. In other words, the bypass switch 63 is connected in parallel to the parallel switch 60. In this embodiment, the bypass switch 63 is a mechanical relay. When the bypass switch 63 is turned off, it blocks bidirectional current flow, and when turned on, it allows bidirectional current flow.

[0060] 8 shows the procedure of the external charging and power supply control process, which is a control process for the parallel switch 60 and the bypass switch 63. This process is repeatedly executed by the EVECU 100, for example, at a predetermined control cycle.

[0061] In step S10, it is determined whether or not an instruction for external power feeding control has been issued for the high-voltage power feed target section 220 or the low-voltage power feed target section 230. If the determination in step S10 is affirmative, the process proceeds to step S11, where the parallel switch 60 and the bypass switch 63 are turned off.

[0062] In step S12, it is determined whether or not an instruction has been issued for external charging control of the high-voltage charger 200. If the determination in step S12 is affirmative, the process proceeds to step S11.

[0063] In step S13, it is determined whether or not an instruction has been issued for external charging control of the low-voltage charger 210. If the determination in step S13 is affirmative, the process proceeds to step S14, in which the parallel switch 60 is turned off and the bypass switch 63 is turned on.

[0064] The charging current (e.g., rated charging current) flowing through the first storage battery 31 during external charging control of the low-voltage charger 210 is larger than the discharging current (e.g., rated discharging current) flowing through the first storage battery 31 during external power feeding control for the low-voltage power feeding target unit 230. For this reason, in this embodiment, in step S14, the bypass switch 63, which has a larger current capacity than the regulating diode 61, is turned on. For this reason, the current capacity of the regulating diode 61, which constitutes a semiconductor relay together with the parallel switch 60, can be reduced, and the semiconductor relay can be made smaller.

[0065] Fourth Embodiment The fourth embodiment will be described below with reference to the drawings, focusing on differences from the second and third embodiments. In this embodiment, as shown in FIG. 9 , the power conversion device includes a bypass switch SMBP. The bypass switch SMBP electrically connects the high-potential-side path 22H and the positive terminal of the first storage battery 31. That is, the bypass switch SMBP is connected in parallel to the parallel switch SMRA. In this embodiment, the bypass switch SMBP is a mechanical relay. When the bypass switch SMBP is turned off, it blocks bidirectional current flow, and when turned on, it allows bidirectional current flow. In this embodiment, the current capacity of the bypass switch SMBP is greater than the current capacity of the regulating diode DA.

[0066] 10 shows the procedure of the external charging and power supply control process, which is a control process for the parallel switch 60 and the bypass switch 63. This process is repeatedly executed by the EVECU 100, for example, at a predetermined control cycle.

[0067] If it is determined in step S10 that external power feeding control for the high-voltage power feed target unit 220 or the low-voltage power feed target unit 230 has been instructed, or if it is determined in step S12 that external charging control for the high-voltage charger 200 has been instructed, the process proceeds to step S15. In step S15, the parallel switch SMRA and the bypass switch SMBP are turned off.

[0068] If it is determined in step S13 that external charging control of the low-voltage charger 210 has been instructed, the process proceeds to step S16, where the parallel switch SMRA is turned off and the bypass switch SMBP is turned on.

[0069] According to the present embodiment described above, it is possible to achieve the same effects as those of the third embodiment.

[0070] Fifth Embodiment A 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. 11 , a connection path 73 electrically connects the neutral point O of the armature winding 11 and the negative terminal of the first storage battery 31.

[0071] The power conversion device includes a parallel switch 160 and a regulating diode 161. The parallel switch 160 electrically connects the positive terminal of the second storage battery 32 and the positive terminal of the first storage battery 31. A first end of the neutral point capacitor 75 is connected to a portion of the connection path 73 between the first motor-side switch 71 and the second motor-side switch 72. A second end of the neutral point capacitor 75 is connected to the high-potential side path 22H.

[0072] In this embodiment, the parallel switch 160 is a voltage-controlled semiconductor switching element, specifically an IGBT. The collector of the parallel switch 160 is connected to the positive terminal of the first storage battery 31 via the first fuse 41, and the emitter of the parallel switch 160 is connected to the positive terminal of the second storage battery 32. Note that the parallel switch 160 is not limited to an IGBT, and may be, for example, an N-channel MOSFET including a body diode.

[0073] The regulating diode 161 is an element for suppressing a large current (e.g., inrush current) from flowing from the first storage battery 31 to the second storage battery 32 via the inverter 20, the armature winding 11, and the connection path 73 when external power supply control is performed while the terminal voltage of the first storage battery 31 relative to the second storage battery 32 is high. The anode of the regulating diode 161 is connected to the emitter of the parallel switch 160, and the cathode of the regulating diode 161 is connected to the collector of the parallel switch 160. As a result, the regulating diode 161 regulates (e.g., blocks) the flow of current in a specific direction from the high-potential side path 22H toward the regulating diode 161, and allows the flow of current in the direction opposite to the specific direction. In this embodiment, the regulating diode 161 corresponds to a "first regulating unit."

[0074] Next, the external charging control of this embodiment will be described. Fig. 12 shows the control state of each switch during external charging control using the high-voltage charger 200. When the EVECU 100 determines that the external charger connected to the power conversion device is the high-voltage charger 200, it turns off the pre-charge main switch SMRP, the parallel switch 160, the first motor-side switch 71, the second motor-side switch 72, and the upper and lower arm switches SWH, SWL of all phases of the inverter 20, and turns on the high-potential side main switch SMRH, the low-potential side main switch SMRL, and the inter-battery switch 50. As a result, the first storage battery 31 and the second storage battery 32 are charged while connected in series to the high-voltage charger 200.

[0075] 13 shows the control state of each switch during external charging control using the low-voltage charger 210. When the EVECU 100 determines that the external charger connected to the power conversion device is the low-voltage charger 210, it turns off the pre-charge main switch SMRP and the inter-battery switch 50, and turns on the high-potential side main switch SMRH, the low-potential side main switch SMRL, the parallel switch 160, the first motor-side switch 71, and the second motor-side switch 72. This causes the second storage battery 32 to be charged.

[0076] In the external charging control by the low-voltage charger 210, the EVECU 100 performs switching control to alternately turn on the upper and lower arm switches SWH, SWL of at least one phase, or performs switching control to switch on the lower arm switch SWL of at least one phase while keeping the upper arm switches SWH of all phases of the inverter 20 off, thereby stepping down the output voltage of the low-voltage charger 210 and supplying it to the first storage battery 31. More specifically, the EVECU 100 performs step-down control, which is the switching control described above, to control the neutral point capacitor voltage VN to a target charging voltage. This charges the first storage battery 31. Because the terminal voltage of the first storage battery 31 is lower than the terminal voltage of the second storage battery 32, the target charging voltage of the first storage battery 31 is lower than the target charging voltage of the second storage battery 32.

[0077] 14 shows the control state of each switch during external power supply control in which power is supplied from the first and second storage batteries 31, 32 to the high-voltage power supply target unit 220. When the EVECU 100 determines that the power supply target unit connected to the power conversion device is the high-voltage power supply target unit 220, it turns off the pre-charge main switch SMRP, the parallel switch 160, the first motor-side switch 71, the second motor-side switch 72, and the upper and lower arm switches SWH, SWL of all phases of the inverter 20, and turns on the connection switches DCRH, DCRL, the high-potential-side main switch SMRH, the low-potential-side main switch SMRL, and the inter-battery switch 50. As a result, power is supplied from the first storage battery 31 and the second storage battery 32 to the high-voltage power supply target unit 220.

[0078] 15 shows the control state of each switch during external power supply control in which power is supplied from the first and second storage batteries 31, 32 to the low-voltage power supply target unit 230. When the EVECU 100 determines that the power supply target unit connected to the power conversion device is the low-voltage power supply target unit 230, it turns off the pre-charge main switch SMRP and the inter-battery switch 50 and turns on the connection switches DCRH, DCRL, the high-potential side main switch SMRH, the low-potential side main switch SMRL, the parallel switch 160, the first motor-side switch 71, and the second motor-side switch 72. As a result, power is supplied from the second storage battery 32 to the low-voltage power supply target unit 230.

[0079] In the external power supply control for the low-voltage power supply target portion 230, the EVECU 100 performs switching control to alternately turn on the upper and lower arm switches SWH, SWL of at least one phase, or performs switching control of the upper arm switch SWH of at least one phase while keeping the lower arm switches SWL of all phases of the inverter 20 off, thereby boosting the output voltage of the first storage battery 31 and supplying it to the low-voltage power supply target portion 230. More specifically, the EVECU 100 performs boost control, which is the switching control for controlling the power supply voltage VB to the target power supply voltage. As a result, power is supplied from the first storage battery 31 to the low-voltage power supply target portion 230.

[0080] The external power supply control may be started in a state in which the inter-terminal voltage of the first storage battery 31 is higher than that of the second storage battery 32. In this case, when a switch such as the high-potential-side main switch SMRH is turned on during the external power supply control, there is a concern that an overcurrent may flow from the first storage battery 31 to a closed circuit including the second storage battery 32, the low-potential-side path 22L, the lower-arm diode DL, the armature winding 11, and the connection path 73. In this case, for example, each of the main switches SMRH and SMRL may fail (e.g., be welded).

[0081] In the present embodiment, similarly to the first embodiment, a regulating diode 161 is provided. Therefore, even if the inter-terminal voltage of the first storage battery 31 is higher than that of the second storage battery 32, it is possible to suppress the occurrence of a situation in which an overcurrent flows.

[0082] Sixth Embodiment A sixth embodiment will be described below with reference to the drawings, focusing on differences from the fifth embodiment. In this embodiment, as shown in FIG. 16 , the installation positions of the regulating diode and the regulating switch are changed.

[0083] The power conversion device includes a regulating switch 162, a regulating diode DB, and a parallel switch SMRB. The regulating switch 162 electrically connects the positive terminal of the first storage battery 31 and the positive terminal of the second storage battery 32. In this embodiment, the regulating switch 162 is a mechanical relay. When the regulating switch 162 is turned off, it blocks bidirectional current flow, and when turned on, it allows bidirectional current flow. The regulating switch 162 is not limited to a mechanical relay, and may be a semiconductor switching element such as an IGBT or an N-channel MOSFET.

[0084] The parallel switch SMRB is connected in parallel to the low-side main switch SMRL. In this embodiment, the parallel switch SMRB is a voltage-controlled semiconductor switching element, specifically an IGBT. The regulating diode DB has the same function as the regulating diode 161 in the fifth embodiment. In this embodiment, the regulating diode DB corresponds to the "second regulating unit," and the regulating switch 162 corresponds to the "first regulating unit."

[0085] In this embodiment, during external charging control using the high-voltage charger 200, the regulating switch 162 is turned off instead of the parallel switch 160 of the fifth embodiment, and the parallel switch SMRB is turned on instead of the low-potential side main switch SMRL of the fifth embodiment. Furthermore, during external charging control using the low-voltage charger 210, the parallel switch SMRB and the regulating switch 162 are turned on instead of the low-potential side main switch SMRL and the parallel switch 160 of the fifth embodiment.

[0086] During external power feeding control for feeding power to the high-voltage power feed target unit 220, the regulating switch 162 is turned off instead of the parallel switch 160 of the fifth embodiment, and the parallel switch SMRB is turned on instead of the low-potential side main switch SMRL of the fifth embodiment. Moreover, during external power feeding control for feeding power to the low-voltage power feed target unit 230, the parallel switch SMRB is turned on instead of the low-potential side main switch SMRL of the fifth embodiment, and the regulating switch 162 is turned off instead of the parallel switch 160 of the fifth embodiment.

[0087] According to the present embodiment described above, it is possible to achieve the same effects as those of the fifth embodiment.

[0088] Seventh Embodiment The seventh embodiment will be described below with reference to the drawings, focusing on differences from the fifth embodiment. In this embodiment, as shown in FIG. 17 , the power conversion device includes a bypass switch 163. The bypass switch 163 electrically connects the positive terminal of the first storage battery 31 and the positive terminal of the second storage battery 32. That is, the bypass switch 163 is connected in parallel to the parallel switch 160. In this embodiment, the bypass switch 163 is a mechanical relay. When the bypass switch 163 is turned off, it blocks bidirectional current flow, and when turned on, it allows bidirectional current flow. Incidentally, the bypass switch 163 is not limited to a mechanical relay, and may be, for example, a semiconductor switching element.

[0089] Next, differences between the processing executed by the EVECU 100 and the processing shown in FIG. 8 will be described.

[0090] If it is determined that external power supply control has been instructed for the high-voltage power supply target unit 220 or the low-voltage power supply target unit 230, or if it is determined that external charging control for the high-voltage charger 200 has been instructed, in step S11, the parallel switch 160 and the bypass switch 163 are turned off.

[0091] If it is determined that external charging control of the low-voltage charger 210 has been instructed, in step S14, the parallel switch 160 is turned off and the bypass switch 163 is turned on.

[0092] In this embodiment, the charging current (e.g., rated charging current) flowing through the second storage battery 32 during external charging control of the low-voltage charger 210 is greater than the discharging current (e.g., rated discharging current) flowing through the second storage battery 32 during external power feeding control for the low-voltage power feeding target unit 230. Therefore, in step S14, the bypass switch 163, which has a larger current capacity than the regulating diode 161, is turned on. This makes it possible to achieve the same effects as in the third embodiment.

[0093] Eighth Embodiment The eighth embodiment will be described below with reference to the drawings, focusing on differences from the sixth embodiment. In this embodiment, as shown in FIG. 18 , the power conversion device includes a bypass switch SMPP. The bypass switch SMPP electrically connects the high-potential-side path 22H and the positive terminal of the first storage battery 31. A parallel switch SMRB and a regulating diode DB are connected in parallel to the bypass switch SMPP. In this embodiment, the bypass switch SMPP is a mechanical relay. When the bypass switch SMPP is turned off, it blocks bidirectional current flow, and when turned on, it allows bidirectional current flow. Incidentally, the bypass switch SMPP is not limited to a mechanical relay, and may be, for example, a semiconductor switching element.

[0094] Next, differences between the processing executed by the EVECU 100 and the processing shown in FIG. 10 will be described.

[0095] If it is determined that external power supply control for the high-voltage power supply target unit 220 or the low-voltage power supply target unit 230 has been instructed, or if it is determined that external charging control for the high-voltage charger 200 has been instructed, in step S15, the parallel switch SMRB and the bypass switch SMPP are turned off.

[0096] If it is determined that external charging control of the low-voltage charger 210 has been instructed, in step S16, the parallel switch SMRB is turned off and the bypass switch SMPP is turned on.

[0097] In this embodiment, the charging current (e.g., rated charging current) flowing through the second storage battery 32 during external charging control of the low-voltage charger 210 is greater than the discharging current (e.g., rated discharging current) flowing through the second storage battery 32 during external power feeding control of the low-voltage power feeding target unit 230. Therefore, in step S14, the bypass switch SMPP, which has a larger current capacity than the regulating diode DB, is turned on. This makes it possible to achieve the same effects as in the fourth embodiment.

[0098] Other Embodiments The above-described embodiments may be modified as follows.

[0099] In the configurations of FIGS. 1 and 7, the parallel switch 60 does not have to be provided.

[0100] In the configurations of FIGS. 6 and 9, the parallel switch SMRA does not have to be provided.

[0101] In the configurations of FIGS. 11 and 17, the parallel switch 160 does not have to be provided.

[0102] In the configurations of FIGS. 16 and 18, the parallel switch SMRB does not have to be provided.

[0103] In the configuration of Fig. 1 , instead of the parallel switch 60 and the regulating diode 61, as shown in Fig. 19 , a first parallel switch 260A, a first regulating diode 261A connected in parallel to the first parallel switch 260A, a second parallel switch 260B, and a second regulating diode 261B connected in parallel to the second parallel switch 260B may be used. Each of the parallel switches 260A and 260B is an IGBT. The collectors of the parallel switches 260A and 260B are connected to each other. The emitter of the second parallel switch 260B is connected to the negative terminal of the first storage battery 31.

[0104] The anode of the first regulating diode 261A is connected to the emitter of the first parallel switch 260A, and the anode of the second regulating diode 261B is connected to the emitter of the second parallel switch 260B.

[0105] When external charging control of the low-voltage charger 210 is performed, the EVECU 100 turns on the first parallel switch 260A and turns on or off the second parallel switch 260B. On the other hand, when external power feeding control of the low-voltage power feeding target unit 230 is performed, the EVECU 100 turns on the second parallel switch 260B and turns on or off the first parallel switch 260A.

[0106] The switch shown in Fig. 19 can also be applied to the configuration of Fig. 11. More specifically, the emitter of the second parallel switch 260B is connected to the positive terminal of the second storage battery 32, as shown in Fig. 20.

[0107] When external charging control of the low-voltage charger 210 is performed, the EVECU 100 turns on the second parallel switch 260B and turns on or off the first parallel switch 260A. On the other hand, when external power feeding control is performed for the low-voltage power feeding target unit 230, the EVECU 100 turns on the first parallel switch 260A and turns on or off the second parallel switch 260B. Note that some components are not shown in Figures 19 and 20.

[0108] In the configurations of FIGS. 7 and 9, the bypass switch is not limited to a mechanical relay, and may be, for example, a semiconductor switching element.

[0109] In each of the above embodiments, the power conversion device does not necessarily have to include either the first or second motor-side switch 71, 72. Furthermore, the power conversion device does not necessarily have to include both the first and second motor-side switches 71, 72.

[0110] The switches of the inverter 20 are not limited to IGBTs, and may be, for example, N-channel MOSFETs having body diodes.

[0111] The fuses 41 and 42 do not have to be provided.

[0112] 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.

[0113] The control devices that perform external charging and power supply control are not limited to the above examples. For example, each control may be performed by cooperation between the battery ECU 90 and the EVECU 100 and a control device other than the battery ECU 90 and the EVECU 100, or each control may be performed by a control device other than the battery ECU 90 and the EVECU 100.

[0114] 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.

[0115] The mobile body on which the power conversion device is mounted is not limited to a vehicle, but may be, for example, an aircraft or a ship.Furthermore, the power conversion device is not limited to a mobile body, but may be a stationary device.

[0116] The control device and 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 device and 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 device and 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 in a computer-readable non-transitory tangible recording medium as instructions executed by a computer.

[0117] 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 power conversion device comprising: a multi-phase inverter (20) having upper and lower arm switches (SWH, SWL) and upper and lower arm diodes (DH, DL) connected in anti-parallel to the upper and lower arm switches; and a motor (10) having an armature winding (11) electrically connected to a low potential side terminal of the upper arm switch of each phase and a high potential side terminal of the lower arm switch of each phase; an inter-storage unit switch (50) that, when turned on, electrically connects a negative terminal of a first storage unit (31) and a positive terminal of a second storage unit (32), and, when turned off, electrically disconnects the negative terminal of the first storage unit and the positive terminal of the second storage unit; a high potential side path (22H) electrically connected to the high potential side terminal of the upper arm switch of each phase; and a low potential side path (22L) that electrically connects the low potential side terminal of the lower arm switch of each phase and the negative terminal of the second storage unit; a connection path (73) electrically connecting the positive terminal of the second storage unit or the negative terminal of the first storage unit to the armature winding; a first regulating unit (61, 62, 161, 162) electrically connecting either the positive terminal or the negative terminal of the first storage unit and each of the second storage units; and a second regulating unit (SMRH, DA, DB) electrically connecting the high potential side path and the positive terminal of the first storage unit, wherein one of the first regulating unit and the second regulating unit (61, DA, 161, DB, 260A, 261A, 260B, 261B) has a function of regulating a flow of current in a specific direction from the high potential side path side to the first regulating unit side and allowing a flow of current in a direction opposite to the specific direction, and the other is a regulating switch (SMRH, 62, 162) that is turned on or off, a control device (90, 100) that performs external power supply control to supply power to an external power supply target part (230) by controlling switching of a target switch that is at least one of the upper and lower arm switches while turning off the inter-storage unit switch and turning on the regulating switch, thereby causing a current to flow in a closed circuit that includes the external power supply target part, the connection path, the armature winding, and the inverter, when the external power supply target part (230) is electrically connected to the high potential side path and the low potential side path.

2. The power conversion device according to claim 1, wherein the connection path electrically connects the positive terminal of the second storage unit and the armature winding, the first regulating unit (61, 62) electrically connects the negative terminal of the first storage unit and the negative terminal of the second storage unit, the second regulating unit (SMRH, DA) electrically connects the high potential side path and the positive terminal of the first storage unit, and the control device performs switching control of the lower arm switch, which is the target switch, in the external power supply control.

3. The power conversion device according to claim 1, wherein the one of the first regulating unit and the second regulating unit that is not the regulating switch is a regulating diode (61, DA), and further comprising a parallel switch (60, SMRA) connected in parallel to the regulating diode.

4. The power conversion device according to claim 3, wherein, in the external power supply control, the control device turns off the parallel switch, and when an external charger (210) is electrically connected to the high potential side path and the low potential side path, turns off the inter-storage unit switch and turns on the regulating switch (SMRH, 62) and the parallel switch (60, SMRA), thereby performing switching control of the upper arm switch that is the target switch, thereby causing a current to flow in a closed circuit that includes the external charger, the inverter, the armature winding, the connection path, and the second storage unit to charge the second storage unit, and performing external charging control that causes a current to flow in a closed circuit that includes the external charger, the high potential side path, the parallel switch, and the first storage unit to charge the first storage unit.

5. A power conversion device as described in claim 2, wherein the one of the first regulating unit and the second regulating unit that is not the regulating switch is a regulating diode (61, DA), and further comprising a bypass switch (63, SMBP) connected in parallel to the regulating diode, and the current capacity of the bypass switch is greater than the current capacity of the regulating diode.

6. The power conversion device according to claim 5, wherein the control device, in the external power supply control, turns off the bypass switch, and when an external charger (210) is electrically connected to the high potential side path and the low potential side path, turns off the inter-storage unit switch and turns on the regulating switch and the bypass switch, thereby performing switching control of the upper arm switch which is the target switch, thereby causing a current to flow in a closed circuit including the external charger, the inverter, the armature winding, the connection path, and the second storage unit to charge the second storage unit, and performing external charging control of causing a current to flow in a closed circuit including the external charger, the high potential side path, the first regulating unit, the first storage unit, and the bypass switch to charge the first storage unit, and a charging current flowing in the first storage unit in the external power supply control is larger than a discharging current flowing in the first storage unit in the external power supply control.

7. The power conversion device according to claim 1, wherein the connection path electrically connects the negative terminal of the first storage unit and the armature winding, the first regulating unit (161, 162) electrically connects the positive terminal of the first storage unit and the positive terminal of the second storage unit, and the control device performs switching control of the upper arm switch, which is the target switch, in the external power supply control.

8. The power conversion device according to claim 7, wherein the one of the first regulating unit and the second regulating unit that is not the regulating switch is a regulating diode (161, DB), and further comprising a parallel switch (160, SMRB) connected in parallel to the regulating diode.

9. The power conversion device according to claim 8, wherein, in the external power supply control, the control device turns off the parallel switch, and when an external charger (210) is electrically connected to the high potential side path and the low potential side path, turns off the inter-storage unit switch and turns on the regulating switch (SMRH, 162) and the parallel switch (160, SMRB), thereby performing switching control of the lower arm switch that is the target switch, thereby causing a current to flow in a closed circuit that includes the external charger, the inverter, the armature winding, the connection path, and the first power storage unit to charge the first power storage unit, and causing a current to flow in a closed circuit that includes the external charger, the high potential side path, the parallel switch, and the second power storage unit to charge the second power storage unit.

10. A power conversion device as described in claim 7, wherein the one of the first regulating unit and the second regulating unit that is not the regulating switch is a regulating diode (161, DB), and further comprising a bypass switch (163, SMPP) connected in parallel with the regulating diode, and the current capacity of the bypass switch is greater than the current capacity of the regulating diode.

11. The power conversion device according to claim 10, wherein the control device, in the external power supply control, turns off the bypass switch, and when an external charger (210) is electrically connected to the high potential side path and the low potential side path, turns off the inter-storage unit switch and turns on the regulating switch and the bypass switch, thereby performing switching control of the lower arm switch which is the target switch, thereby causing a current to flow through a closed circuit including the external charger, the inverter, the armature winding, the connection path, the bypass switch, and the first storage unit to charge the first storage unit, and causing a current to flow through a closed circuit including the external charger, the high potential side path, the first regulating unit, the bypass switch, and the second storage unit to charge the second storage unit, and a charging current flowing through the second storage unit in the external power supply control is larger than a discharging current flowing through the second storage unit in the external power supply control.

12. The power conversion device according to claim 5 or 10, further comprising a parallel switch (60, SMRA, 160, SMRB) connected in parallel to the regulating diode, and a semiconductor relay having the regulating diode, wherein the bypass switch is a mechanical relay.

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