Power conversion device and program

Abstract

To provide a power conversion device and a program that can eliminate a situation where an overcurrent flows in the power conversion device.SOLUTION: The power conversion device includes a motor 10, an inverter 20, a high-potential side path 22H, a low-potential side path 22L, an inter-battery switch 50, a bypass switch 60, a connection path 73, and a motor ECU 100. The motor ECU 100 performs a switching control on a target switch, which is at least one of upper and lower arm switches (SUH to SWL) on the inverter 20 to allow current to flow through the connection path 73. The motor ECU 100 determines whether a short-circuit fault has occurred in at least one of the upper and lower arm switches, and when a short circuit fault is determined to have occurred, a current reduction process is performed to reduce a current flowing in the connection path 73.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a power conversion device and a program. [Background technology]

[0002] Conventionally, a power conversion device including an inverter and a motor electrically connected to the inverter is known. The inverter has upper and lower arm switches of multiple phases. The armature winding is 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. Note that a technology related to such a power conversion device is described in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-047677 A Summary of the Invention [Problem to be solved by the invention]

[0004] If a short circuit occurs in at least one of the upper and lower arm switches, an overcurrent may flow in the power conversion device.

[0005] The main object of the present disclosure is to provide a power conversion device and a program capable of eliminating a situation in which an overcurrent flows within the power conversion device when a short circuit failure occurs in at least one of the upper and lower arm switches. [Means for solving the problem]

[0006] The present disclosure provides an inverter having upper and lower arm switches for multiple phases; a motor having an armature winding 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; In a power conversion device comprising: a high potential side path electrically connecting a positive electrode terminal of the first power storage unit and a high potential side terminal of the upper arm switch; a low potential side path electrically connecting a negative electrode terminal of the second power storage unit and a low potential side terminal of the lower arm switch; a connection path electrically connecting the negative terminal of the first power storage unit or the positive terminal of the second power storage unit to the armature winding; an inter-power storage unit switch that, when turned on, electrically connects the negative electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit and, when turned off, electrically disconnects the negative electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit; a bypass switch that electrically connects negative electrode terminals of the first power storage unit and the second power storage unit to each other and electrically connects positive electrode terminals of the first power storage unit and the second power storage unit to each other; a control device that performs switching control of a target switch, which is at least one of the upper and lower arm switches, so as to pass a current through the connection path while turning off the inter-storage unit switch and turning on the bypass switch; Equipped with The control device includes: determining whether or not a short circuit has occurred in at least one of the upper and lower arm switches; When it is determined that the short circuit fault has occurred, a current reduction process is performed to reduce the current flowing through the connection path.

[0007] The power conversion device of the present disclosure includes a high-potential side path, a low-potential side path, a connection path, an inter-storage unit switch, a bypass switch, and a control device. With this configuration, when the inter-storage unit switch is turned off and the bypass switch is turned on, the control device executes switching control of a target switch, which is at least one of the upper and lower arm switches, so that a current flows in the connection path.

[0008] Here, if a short circuit occurs in at least one of the upper and lower arm switches, an overcurrent may flow in the power conversion device.

[0009] In consideration of this, the control device determines whether or not a short circuit has occurred in at least one of the upper and lower arm switches. If the control device determines that a short circuit has occurred, it performs a current reduction process to reduce the current flowing through the connection path. This makes it possible to eliminate the situation in which an overcurrent flows in the power conversion device. [Brief description of the drawings]

[0010] [Figure 1] 1 is an overall configuration diagram of a system according to a first embodiment. [Diagram 2] FIG. 4 is a diagram showing the control state of the switches during high voltage charging. [Diagram 3] FIG. 4 is a diagram showing the control state of the switches during low-voltage charging. [Figure 4] 11 is a flowchart showing a procedure for a current reduction process. [Diagram 5] 10 is a flowchart showing a procedure of a current reduction process according to a second embodiment. [Figure 6] FIG. 11 is a diagram showing a control state of a switch during high voltage power supply according to the third embodiment. [Figure 7] FIG. 4 is a diagram showing the control state of the switch during low voltage power supply. [Figure 8] FIG. 13 is an overall configuration diagram of a system according to a fourth embodiment. [Figure 9] FIG. 4 is a diagram showing the control state of the switches during low-voltage charging. [Figure 10] 11 is a flowchart showing a procedure for a current reduction process. [Figure 11] FIG. 4 is a diagram showing the control state of the switch during low voltage power supply. DETAILED DESCRIPTION OF THE PREFERRED 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 given the same reference numerals or reference numerals with different digits of 100 or more. For corresponding and / or associated parts, the description of other embodiments may be referred to.

[0012] First Embodiment Hereinafter, a first embodiment of a power conversion device according to the present disclosure will be described with reference to the drawings. The power conversion device of the present embodiment is mounted on a vehicle such as an electric vehicle or a hybrid vehicle, and constitutes 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, 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 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 driving the vehicle.

[0014] The inverter 20 includes three phases of series-connected upper and lower arm switches. More specifically, the inverter 20 includes U-, V-, and W-phase upper arm switches SUH, SVH, and SWH, and U-, V-, and W-phase lower arm switches SUL, SVL, and SWL. The U-, V-, and W-phase upper arm diodes DUH, DVH, and DWH, which are freewheel diodes, are connected in inverse parallel to the U-, V-, and W-phase upper arm switches SUH, SVH, and SWH, and the U-, V-, and W-phase lower arm diodes DUL, DVL, and DWL, which are freewheel diodes, are connected in inverse parallel to the U-, V-, and W-phase lower arm switches SUL, SVL, and SWL. In this embodiment, the switches SUH, SVH, SWH, SUL, SVL, and SWL are IGBTs.

[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] First ends of the U-, V-, and W-phase armature windings 11U, 11V, and 11W are connected to a connection point between emitters, which are low potential terminals of the U-, V-, and W-phase upper arm switches SUH, SVH, and SWH, and collectors, which are high potential terminals of the U-, V-, and W-phase lower arm switches SUL, SVL, and SWL, via conductive members 23 such as bus bars. Second ends of the U-, V-, and W-phase armature windings 11U, 11V, and 11W are connected to each other at a neutral point O. In this embodiment, the U-, V-, and W-phase armature windings 11U, 11V, and 11W are set to have the same number of turns. As a result, the U-, V-, and W-phase armature windings 11U, 11V, and 11W are set to have the same inductance, for example.

[0017] A high potential side path 22H is connected to the collectors of the U-, V-, and W-phase upper arm switches SUH, SVH, and SWH. A low potential side path 22L is connected to the emitters of the U-, V-, and W-phase lower arm switches SUL, SVL, and SWL.

[0018] The system includes a first storage battery 31 (corresponding to a "first power storage unit") and a second storage battery 32 (corresponding to a "second power storage unit"). Each of the storage batteries 31, 32 is a power supply source for rotating and driving the rotor of the motor 10. Each of the storage batteries 31, 32 is a battery pack including a series connection of a plurality of unit batteries. The unit battery is a single battery cell that is a single cell, or a series connection of a plurality of battery cells. In this embodiment, the full charge capacity (specifically, for example, rated full charge capacity) [Ah] of each of the unit batteries constituting the first storage battery 31 and the second storage battery 32 is the same. The positive terminal of the first storage battery 31 is connected to the high potential side path 22H via a high potential side fuse 41, and the negative terminal of the second storage battery 32 is connected to the low potential side path 22L via a low potential side fuse 42. The terminal voltages (for example, rated voltages) of each of the battery cells constituting the battery pack are set to be the same, for example. The battery cells are, for example, secondary batteries such as lithium ion batteries. In this embodiment, the terminal voltage (e.g., rated voltage) of the first storage battery 31 is higher than the terminal voltage (e.g., rated voltage) of the second storage battery 32. This configuration can be realized, for example, by making the number of unit batteries constituting the first storage battery 31 greater than the number of unit batteries constituting the second storage battery 32.

[0019] The power conversion device includes a main switch for electrically connecting or disconnecting the first and second storage batteries 31, 32 and the inverter 20. More specifically, a high-side main switch SMRH, a low-side main switch SMRL, and a pre-charge main switch SMRP are provided as the main switches. In this embodiment, each of the main switches SMRH, SMRL, and SMRP is a mechanical relay. When the main switches SMRH, SMRL, and SMRP are turned off, they block bidirectional current flow, and when turned on, they allow bidirectional current flow. The high-side main switch SMRH connects the high-side fuse 41 and the high-side path 22H. The low-side main switch SMRL connects the low-side fuse 42 and the low-side path 22L. A series connection of the pre-charge main switch SMRP and the pre-charge resistor 40 is connected in parallel to the low-side main switch SMRL. The main switches SMRH, SMRL, and SMRP are not limited to mechanical relays, and may be, for example, semiconductor switching elements.

[0020] Each of the storage batteries 31, 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 and 32 can supply power to a power supply target unit outside the vehicle through external power supply control. When the power supply target unit is a system power source, the external power supply control is also called V2G (Vehicle to Grid). When the power supply target unit 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 between an external charger or a power supply target unit and the first and second storage batteries 31, 32. In this embodiment, each of the connection switches DCRH, DCRL is a mechanical relay. When each of the connection switches DCRH, DCRL is turned off, it blocks the flow of bidirectional current, and when each of the connection switches DCRH, DCRL is turned on, it allows the flow of bidirectional current. 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, 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-power storage unit switch"), a bypass 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, the bypass switch 60, and each of the motor-side switches 71, 72 are mechanical relays. When the inter-battery switch 50, the bypass switch 60, and each of the motor-side switches 71, 72 are turned off, they block the flow of bidirectional current, and when they are turned on, they allow the flow of bidirectional current. Note that the inter-battery switch 50, the bypass switch 60, 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. On the other hand, 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] The bypass switch 60 connects the negative terminal of the first storage battery 31 and the low potential side path 22L. When the bypass switch 60 is turned on, the negative terminal of the first storage battery 31 and the negative terminal of the second storage battery 32 are electrically connected to each other. On the other hand, when the bypass 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 from each other.

[0026] In this embodiment, the first storage battery 31 and the second storage battery 32 configure a battery unit 30.

[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. A second motor-side switch 72 and a first motor-side switch 71 are provided in this order from the second storage battery 32 to the connection path 73.

[0028] The power conversion device includes a neutral point capacitor 74 that is a capacitor 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 neutral point O of the armature winding 11 and the first end of the neutral point capacitor 74 are electrically connected. On the other hand, when the first motor side switch 71 is turned off, the neutral point O and the first end of the neutral point capacitor 74 are electrically disconnected. When the second motor side switch 72 is turned on, the first end of the neutral point capacitor 74 and the positive terminal of the second storage battery 32 are electrically connected. On the other hand, when the second motor side switch 72 is turned off, the first end of the neutral point capacitor 74 and the positive terminal of the second storage battery 32 are electrically disconnected.

[0030] The power conversion device includes a first current sensor 81A, a second current sensor 81B, a phase current sensor 82, and a motor current sensor 83 as current sensors for detecting currents flowing through various parts of the power conversion device. The first current sensor 81A detects a current flowing through the first storage battery 31, and the second current sensor 81B detects a current flowing through the second storage battery 32. The phase current sensor 82 detects a current flowing through the U-, V-, and W-phase armature windings 11U, 11V, and 11W. The motor current sensor 83 detects a current flowing through the connection path 73, and in this embodiment, detects a 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 84 that detects the terminal voltage of the neutral point capacitor 74, a first voltage sensor 85A that detects the terminal voltage of the first storage battery 31, and a second voltage sensor 85B that detects the terminal voltage of the second storage battery 32. The power conversion device also includes a power supply voltage sensor 86 that detects the terminal voltage of the smoothing capacitor 21.

[0032] The system includes a battery ECU 90 that controls the battery unit 30, a motor ECU 100 that controls the inverter 20, and an EVECU 110 that manages the system. The battery ECU 90 is an electronic control unit mainly composed of a microcomputer 91. The motor ECU 100 is an electronic control unit mainly composed of a microcomputer 101. The EVECU 110 is an electronic control unit mainly composed of a microcomputer 111, and is a higher-level control unit than the battery ECU 90 and the motor ECU 100. The battery ECU 90 and the motor ECU 100 are able to exchange information via the EVECU 110.

[0033] Each of the microcomputers 91, 101, and 111 includes a CPU (Central Processing Unit). The functions provided by each of the microcomputers 91, 101, and 111 can be provided by software recorded in a substantial memory device and a computer that executes the software, by software alone, by hardware alone, or by a combination of these. For example, when each of the microcomputers 91, 101, and 111 is provided by an electronic circuit that is hardware, the function can be provided by a digital circuit including a large number of logic circuits, or by an analog circuit. For example, each of the microcomputers 91, 101, and 111 executes a program stored in a non-transitory tangible storage medium as a storage unit provided in the microcomputer. The program includes, for example, a program of a process shown in FIG. 4, which will be described later. A set of instructions that constitute the program is executed, thereby executing 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, OTA (Over The Air), etc.

[0034] The detection values ​​of the first current sensor 81A, the second current sensor 81B, the first voltage sensor 85A, and the second voltage sensor 85B are input to the battery ECU 90. The detection values ​​of the phase current sensor 82, the motor current sensor 83, the capacitor voltage sensor 84, and the power supply voltage sensor 86 are input to the motor ECU 100.

[0035] The motor ECU 100 performs switching control of the upper and lower arm switches SUH-SWL of each phase constituting the inverter 20 to feedback control the control amount of the motor 10 to a command value based on the detection values ​​of each sensor. The control amount is, for example, torque. In each phase, the upper arm switch and the lower arm switch are alternately turned on. Through this feedback control, 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 inter-battery switch 50, the bypass switch 60, and the motor-side switches 71, 72 may be controlled by any one of the battery ECU 90, the motor ECU 100, or the EVECU 110, or may be controlled by an ECU other than the ECUs 90, 100, 110. In this embodiment, hereinafter, the main switches SMRH, SMRL, SMRP, the inter-battery switch 50, the bypass switch 60, and the motor-side switches 71, 72 are assumed to be controlled by the motor ECU 100.

[0037] Next, the external charging control will be described.

[0038] 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 terminal voltage (specifically, the rated voltage) of the series-connected body of the first and second storage batteries 31 and 32, and is, for example, 800V. The charging voltage of the low-voltage charger 210 is lower than the terminal voltage of the series-connected body of the first and second storage batteries 31 and 32, and is higher than the terminal voltage (specifically, the rated voltage) of the first storage battery 31, and is, for example, 400V. When the first and second storage batteries 31 and 32 are 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 performed or when 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.

[0039] 2 shows the control state of each switch during external charging control using the high-voltage charger 200. The high-voltage charger 200 and the power conversion device are electrically connected when the charging plug of the high-voltage charger 200 is electrically connected to each connection switch DCRH, DCRL by the vehicle user. When the motor ECU 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 bypass switch 60, the first motor side switch 71, the second motor side switch 72, and the upper and lower arm switches SUH to 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 connected in series to the high-voltage charger 200. As a result, a 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 state of being connected in series. At this time, since the upper arm switches SUH, SVH, 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.

[0040] 3 shows the control state of each switch during external charging control using the low-voltage charger 210. The low-voltage charger 210 and the power conversion device are electrically connected by electrically connecting the charging plug of the low-voltage charger 210 to each connection switch DCRH, DCRL by the vehicle user. When the motor ECU 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 bypass switch 60, the first motor side switch 71, and the second motor side switch 72. As a result, a current flows through a closed circuit including the low-voltage charger 210, the high-potential side path 22H, the first storage battery 31, the bypass switch 60, and the low-potential side path 22L, and the first storage battery 31 is charged.

[0041] In the external charging control by the low-voltage charger 210, the motor ECU 100 performs switching control to alternately turn on upper and lower arm switches (corresponding to "target switches") of at least one phase, or performs switching control of an upper arm switch (corresponding to "target switch") of at least one phase with the lower arm switches SUL, SVL, and SWL of all phases of the inverter 20 turned off, thereby stepping down the output voltage of the low-voltage charger 210 and supplying it to the second storage battery 32. In detail, the motor ECU 100 performs step-down control, which is the above-mentioned switching control for controlling the voltage detected by the capacitor voltage sensor 84 (hereinafter, 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 of the inverter 20, the armature winding 11, the neutral point O, the first motor side switch 71, the second motor side switch 72, 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 .

[0042] However, during external charging control using the low-voltage charger 210, a short circuit failure may occur in at least one of the upper and lower arm switches. In order to ensure the safety of the power conversion device in this case, the motor ECU 100 performs a current reduction process. FIG. 4 is a flowchart showing the procedure of the current reduction process. This process is executed by the motor ECU 100.

[0043] In step S10, it is determined whether or not a short circuit has occurred in at least one of the upper and lower arm switches. The method for determining whether or not a short circuit has occurred can be any of various well-known methods. For example, it may be determined that a short circuit has occurred when it is determined that the switch is in the on state despite an off command being issued to the switch based on the detection value of the phase current sensor 82.

[0044] In step S11, it is determined whether the switch in which the short circuit has occurred is an upper arm switch or a lower arm switch. If it is determined in step S11 that the switch in which the short circuit has occurred is an upper arm switch, the process proceeds to step S12, where a lower arm switch of a phase different from the phase in which the short circuit has occurred is turned on. This is to cause at least a portion of the current flowing through the connection path 73 to flow to the low potential side path 22L. In the following, for convenience, it is assumed that the U-phase upper arm switch SUH has a short circuit.

[0045] When the U-phase upper arm switch SUH short-circuits during step-down control, an overcurrent flows from the low-voltage charger 210 to the connection path 73 via the high-potential side path 22H, the U-phase upper arm switch SUH, and the U-phase armature winding 11U. In this case, when a lower arm switch of a phase different from the U phase is turned on, at least a part of the current flowing through the connection path 73 flows to the low-potential side path 22L via the armature winding of the phase of the turned-on lower arm switch and the turned-on lower arm switch. This makes it possible to reduce the current flowing through the connection path 73. By reducing the current flowing through the connection path 73, the first motor side switch 71 provided in the connection path 73 can be switched off without causing an abnormality (e.g., welding) in the first motor side switch 71. As a result, it is possible to eliminate the situation in which an overcurrent flows through the power conversion device.

[0046] In step S12, any one of the V- and W-phase lower arm switches SVL and SWL or both of the V- and W-phase lower arm switches SVL and SWL can be turned on. When both are turned on, the parallel-connected V- and W-phase armature windings 11V and 11W can be utilized, so that at least a part of the current flowing through the connection path 73 can be made to flow more easily to the low-potential side path 22L while further reducing the impedance of the armature winding. As a result, the effect of reducing the current flowing through the connection path 73 can be enhanced.

[0047] In step S13, the process waits until the connection path current IN, which is the detection value of the motor current sensor 83, becomes equal to or less than the first threshold value IthL. The first threshold value IthL is, for example, a current value suitable for turning off the first motor-side switch 71 and is a current value at which an abnormality (e.g., welding) of the first motor-side switch 71 does not occur when the switch is turned off.

[0048] If it is determined in step S13 that the connection path current IN has become equal to or less than the first threshold value IthL, the process proceeds to step S14, where the first motor-side switch 71 is turned off. This makes it possible to interrupt the current flowing through the connection path 73. In the following step S15, the second motor-side switch 72 is turned off. This makes it possible to turn off the second motor-side switch 72 in a state in which no current flows through the second motor-side switch 72. As a result, it is possible to avoid the occurrence of an abnormality (e.g., welding) in the second motor-side switch 72. Note that after the process of step S15, the main switches SMRH, SMRL and the connection switches DCRH, DCRL may be turned off.

[0049] Note that, instead of the process of step S13, for example, a process may be performed in which the elapsed time from the execution of the process of step S12 is counted and a process of waiting until the counted elapsed time reaches a judgment time. The judgment time may be set to a time until the current value flowing through the connection path 73 after the lower arm switch is turned on in step S12 reaches a current value at which an abnormality (e.g., welding) of the first motor side switch 71 due to switching to off does not occur. Also, for example, in the case of a power conversion device in which the current flowing through the connection path 73 immediately decreases after the lower arm switch is turned on in step S12, the process may proceed to step S14 after the process of step S12 is completed.

[0050] If it is determined in step S11 that the switch in which the short circuit has occurred is a lower arm switch, the process proceeds to step S16, where the lower arm switch of a phase other than the phase in which the short circuit has occurred is turned on. The process of step S16 is a process for blowing the low potential side fuse 42. In the following, for the sake of convenience, it is assumed that the U-phase lower arm switch SUL has a short circuit.

[0051] If a short circuit occurs in the U-phase lower arm switch SUL during step-down control, an overcurrent flows from the second storage battery 32 to a closed circuit including the motor-side switches 71, 72, the U-phase armature winding 11U, the U-phase lower arm switch SUL, and the low-potential side path 22L. In this case, when a lower arm switch of a phase other than the U-phase is turned on, the lower arm switches are connected in parallel, and the impedance of the closed circuit decreases. As a result, the current flowing in the closed circuit reaches the melting current of the low-potential side fuse 42, and the low-potential side fuse 42 melts. This makes it possible to eliminate the situation in which an overcurrent flows in the power conversion device.

[0052] In step S16, any one of the V- and W-phase lower arm switches SVL and SWL or both of the V- and W-phase lower arm switches SVL and SWL can be turned on. When both are turned on, the parallel-connected U-, V-, and W-phase armature windings 11U, 11V, and 11W can be used, so that the impedance of the armature windings can be further reduced. As a result, the current flowing through the closed circuit can be increased, and the time from when a short circuit occurs until the current flowing through the closed circuit reaches the melting current of the low potential side fuse 42 can be shortened. For example, the elapsed time from when the process of step S16 is executed is counted, and when it is determined that the counted elapsed time has reached a predetermined time, the process proceeds to step S14. The predetermined time may be set to a time that is assumed to occur when the low potential side fuse 42 melts after the lower arm switches of the different phases are turned on.

[0053] According to the present embodiment described above, it is possible to prevent an overcurrent from flowing in the power conversion device when external charging control is performed.

[0054] <Modification of the first embodiment> The motor ECU 100 may execute only steps S10 to S15 of the process shown in FIG. 4, or may execute only steps S10, S11, S16, S14, and S15 of the process shown in FIG.

[0055] <Second embodiment> The second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In this embodiment, the content of the current reduction process is changed.

[0056] 5 is a flowchart showing a procedure for the current reduction process. This process is executed by the motor ECU 100.

[0057] If it is determined in step S11 that the switch in which the short circuit has occurred is the upper arm switch, the process proceeds to step S17, where the lower arm switch of the same phase as the phase in which the short circuit has occurred is turned on. This is to cause at least a part of the current flowing through the connection path 73 to flow to the low potential side path 22L. By causing at least a part of the current flowing through the connection path 73 to flow to the low potential side path 22L, the high potential side fuse 41 can be blown, and the situation in which an overcurrent flows in the power conversion device can be eliminated. In the following, for the sake of convenience, it is assumed that the U-phase upper arm switch SUH has a short circuit.

[0058] When the U-phase lower arm switch SUL is turned on in a state where the U-phase upper arm switch SUH has a short-circuit fault, a short circuit of the upper and lower arms of the U-phase occurs. In this case, the current flowing from the low-voltage charger 210 to the connection path 73 drops significantly, or the current does not flow through the connection path 73. Meanwhile, the current flowing through the closed circuit including the first storage battery 31, the high potential side path 22H, the U-phase upper arm switch SUH, the U-phase lower arm switch SUL, the low potential side path 22L, and the bypass switch 60 increases, and the current flowing through the closed circuit reaches the blow current of the high potential side fuse 41. As a result, the high potential side fuse 41 blows, and the situation in which an overcurrent flows through the power conversion device can be resolved. After the process of step S17 is completed, the process proceeds to step S14.

[0059] According to the present embodiment described above, it is possible to achieve the same effects as the first embodiment.

[0060] <Modification of the second embodiment> The motor ECU 100 may execute only the processes of steps S10, S11, S17, S14, and S15 of the process shown in FIG. 5, or may execute only the processes of steps S10, S11, S16, S14, and S15 of the process shown in FIG.

[0061] <Third embodiment> Hereinafter, the third embodiment will be described with reference to the drawings, focusing on the differences from the first and second embodiments. In this embodiment, when external power supply control is performed, the processes shown in Figs. 4 and 5 are applied.

[0062] 6 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 motor ECU 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 bypass switch 60, the first motor side switch 71, the second motor side switch 72, and the upper and lower arm switches SUH to 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 brings about a state in which the first storage battery 31 and the second storage battery 32 are connected in series to the high-voltage power supply target 220. As a result, current flows through a closed circuit including the first storage battery 31, the high potential side path 22H, the high voltage power supply target section 220, the low potential 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 section 220.

[0063] 7 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 and 32 to the low-voltage power supply target 230. The rated voltage of the low-voltage power supply target 230 is lower than the rated voltage of the high-voltage power supply target 220. When the motor ECU 100 determines that the power supply target connected to the power conversion device is the low-voltage power supply target 230, it turns off the pre-charge main switch SMRP and the inter-battery switch 50, and turns on the connection switches DCRH and DCRL, the high-potential side main switch SMRH, the low-potential side main switch SMRL, the bypass switch 60, the second motor side switch 72, and the first motor side switch 71. As a result, a current flows through a closed circuit including the first storage battery 31, the high-potential side path 22H, the low-voltage power supply target 230, the low-potential side path 22L, and the bypass switch 60, and power is supplied from the first storage battery 31 to the low-voltage power supply target 230.

[0064] In the external power supply control for the low-voltage power supply target portion 230, the motor ECU 100 performs switching control for alternately turning on upper and lower arm switches (corresponding to "target switches") of at least one phase, or performs switching control for a lower arm switch (corresponding to "target switches") of at least one phase in a state in which the upper arm switches SUH, SVH, and SWH of all phases of the inverter 20 are turned off, thereby boosting the output voltage of the second storage battery 32 and supplying it to the low-voltage power supply target portion 230. In detail, the motor ECU 100 performs boost control, which is the switching control for controlling the power supply voltage VB, which is the detection voltage of the power supply voltage sensor 86, to a target power supply voltage. As a result, a 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 portion 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 portion 230.

[0065] In the external power supply control of this embodiment, the process shown in Fig. 4 can be applied, as in the first embodiment. Moreover, in the external power supply control of this embodiment, the process shown in Fig. 5 can be applied, as in the second embodiment.

[0066] According to the present embodiment described above, it is possible to prevent an overcurrent from flowing in the power conversion device when the external power supply control is performed.

[0067] <Fourth embodiment> The fourth embodiment will be described below with reference to the drawings, focusing on the differences from the first and second embodiments. In this embodiment, as shown in FIG. 8, the connection path 73 electrically connects the neutral point O of the armature winding 11 and the negative terminal of the first storage battery 31. The bypass switch 61 connects the positive terminal of the second storage battery 32 and the high potential side path 22H. The 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. The second end of the neutral point capacitor 75 is connected to the high potential side path 22H.

[0068] In this embodiment, the terminal voltage (for example, rated voltage) of the first storage battery 31 is lower than the terminal voltage (for example, rated voltage) of the second storage battery 32.

[0069] Next, the external charging control of this embodiment will be described. Fig. 9 shows the control state of each switch during external charging control using the low-voltage charger 210. When the motor ECU 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 bypass switch 61, the first motor side switch 71, and the second motor side switch 72. This causes the second storage battery 32 to be charged.

[0070] In the external charging control by the low-voltage charger 210, the motor ECU 100 performs switching control to alternately turn on upper and lower arm switches (corresponding to "target switches") of at least one phase, or performs switching control of a lower arm switch (corresponding to "target switches") of at least one phase with the upper arm switches SUH, SVH, SWH of all phases of the inverter 20 turned off, thereby stepping down the output voltage of the low-voltage charger 210 and supplying it to the first storage battery 31. In detail, the motor ECU 100 performs step-down control, which is the above-mentioned switching control for controlling the neutral point capacitor voltage VN to the target charging voltage. As a result, the first storage battery 31 is charged. Since 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.

[0071] 10 is a flowchart showing the procedure of the current reduction process. This process is executed by, for example, the motor ECU 100. The current reduction process of the present embodiment is the same as the process shown in FIG. 4 except that the process of S16 is not included.

[0072] In the external charging control of this embodiment, similarly to the second embodiment, the process shown in Fig. 5 can be applied instead of the process shown in Fig. 10. In this case, in step S12, by turning on the lower arm switch of the same phase as the phase in which the short circuit fault has occurred, the current flowing through the high / low potential side fuse 41 increases compared to when the lower arm switch of the same phase is turned off, and the high potential side fuse 41 is blown.

[0073] Next, the external power supply control of this embodiment will be described. Fig. 11 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 motor ECU 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 bypass switch 61, 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.

[0074] In the external power supply control for the low-voltage power supply target portion 230, the motor ECU 100 performs switching control for alternately turning on upper and lower arm switches (corresponding to "target switches") of at least one phase, or performs switching control for an upper arm switch (corresponding to "target switches") of at least one phase in a state in which the lower arm switches SUL, SVL, SWL of all phases of the inverter 20 are turned off, thereby boosting the output voltage of the first storage battery 31 and supplying it to the low-voltage power supply target portion 230. In detail, the motor ECU 100 performs boost control, which is the above-mentioned 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.

[0075] In the external power supply control of this embodiment, similarly to the second embodiment, the process shown in Fig. 5 can be applied. In addition, the process shown in Fig. 10 can also be applied.

[0076] According to the present embodiment described above, it is possible to achieve the same effects as the first, second and third embodiments.

[0077] <Other embodiments> Each of the above embodiments may be modified as follows.

[0078] The switch that is turned off in step S14 in FIG. 4 and FIG. 10 may be the bypass switch 60 or the high potential side main switch SMRH.

[0079] The high / low potential side fuse 41 may be connected to the negative terminal of the first storage battery 31. The low potential side fuse 42 may be connected to the positive terminal of the second storage battery 32.

[0080] 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. In addition, the power conversion device does not necessarily have to include both the first and second motor-side switches 71, 72.

[0081] The switches of the inverter 20 are not limited to IGBTs, and may be, for example, N-channel MOSFETs equipped with body diodes. In this case, the high potential side terminal of the N-channel MOSFET becomes the drain, and the low potential side terminal becomes the source.

[0082] The high potential side main switch SMRH does not have to be provided.

[0083] Instead of the low potential side main switch SMRL, a series connection of the pre-charge main switch SMRP and the pre-charge resistor 40 may be connected in parallel to the high potential side main switch SMRH. In this case, the low potential side main switch SMRL does not have to be provided.

[0084] The motor is not limited to a star-connected one, and may be a delta-connected one. The motor and inverter are not limited to a three-phase one, and may be a two-phase one, or a four-phase or more phase one. The motor is not limited to a permanent magnet-type synchronous machine having a permanent magnet as a field pole on the rotor, and may be a wound field-type 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, and may be an induction machine.

[0085] The control device that performs external charging and power supply control is not limited to the motor ECU 100. For example, each control may be performed by a plurality of control devices, such as the battery ECU 90, the EVECU 110, and the motor ECU 100, working together.

[0086] 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 may be one that includes both a storage battery and an electric double-layer capacitor.

[0087] The moving 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. The power conversion device is not limited to a moving body, but may be a stationary device.

[0088] The control device and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control device and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control device and the method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by the computer. [Explanation of symbols]

[0089] 10...motor, 11U, 11V, 11W...armature winding, 20...inverter, 22H...high potential side path, 22L...low potential side path, 31, 32...first and second storage batteries, 50...inter-battery switch, 60...bypass switch, 73...connection path, 100...motor ECU.

Claims

1. An inverter (20) having upper and lower arm switches (SUH to SWL) for multiple phases; a motor (10) having an armature winding (11U to 11W) 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; In a power conversion device comprising: a high potential side path (22H) electrically connecting a positive terminal of the first storage unit (31) and a high potential side terminal of the upper arm switch; a low potential side path (22L) electrically connecting a negative terminal of the second storage unit (32) and a low potential side terminal of the lower arm switch; a connection path (73) electrically connecting the negative terminal of the first storage unit or the positive terminal of the second storage unit to the armature winding; an inter-storage unit switch (50) that, when turned on, electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit, and, when turned off, electrically disconnects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a bypass switch (60, 61) that electrically connects negative electrode terminals of the first power storage unit and the second power storage unit to each other and electrically connects positive electrode terminals of the first power storage unit and the second power storage unit to each other; a control device (100) that performs switching control of a target switch, which is at least one of the upper and lower arm switches, so as to pass a current through the connection path while turning off the inter-storage unit switch and turning on the bypass switch; Equipped with The control device includes: determining whether or not a short circuit has occurred in at least one of the upper and lower arm switches; When it is determined that the short circuit fault has occurred, the power conversion device performs a current reduction process to reduce the current flowing through the connection path.

2. the bypass switch (60) electrically connects the negative electrode terminal of the first power storage unit and the negative electrode terminal of the second power storage unit when turned on, and electrically disconnects the negative electrode terminal of the first power storage unit and the negative electrode terminal of the second power storage unit when turned off; The power conversion device according to claim 1 , wherein the connection path electrically connects the armature winding and a positive terminal of the second power storage unit.

3. The control device includes: The power conversion device according to claim 2, wherein when it is determined that a short circuit fault has occurred in the upper arm switch of any one of the phases, the current reduction process is performed by turning on the lower arm switch of a phase other than the upper arm switch in which the short circuit fault has occurred.

4. A motor-side switch (71) is provided in the connection path, The control device includes: performing the switching control in a state where the inter-storage unit switch is turned off and the bypass switch and the motor-side switch are turned on; The power conversion device according to claim 3 , wherein in the current reduction process, the lower arm switch of a phase different from that of the upper arm switch in which a short circuit has occurred is turned on, and then the motor side switch is turned off.

5. the motor-side switch is a first motor-side switch, a neutral capacitor (74) electrically connecting the low potential side path and the connection path; a second motor-side switch (72) provided in the connection path on the second storage unit side relative to a connection point with the neutral point capacitor; Equipped with The power conversion device according to claim 4 , wherein, in the current reduction process, the control device turns off the first motor side switch and then turns off the second motor side switch.

6. the inverter is a three-phase inverter, The power conversion device according to any one of claims 3 to 5, wherein the control device turns on the lower arm switches of two phases different from the upper arm switch in which a short circuit failure has occurred in the current reduction process.

7. A high-potential side fuse (41) is provided, the high potential side fuse electrically connects the high potential side path and a positive electrode terminal of the first power storage unit, or electrically connects the negative electrode terminal of the first power storage unit and the connection path, The control device includes: The power conversion device according to claim 2, wherein when it is determined that a short circuit fault has occurred in the upper arm switch of any one of the phases, the current reduction process is performed by turning on the lower arm switch of the same phase as the upper arm switch in which the short circuit fault has occurred.

8. A low-side fuse (42) is provided; the low potential side fuse electrically connects a negative electrode terminal of the second power storage unit and the low potential side path, or electrically connects the connection path and a positive electrode terminal of the second power storage unit, The control device includes: The power conversion device according to claim 2, wherein when it is determined that a short circuit failure has occurred in the lower arm switch of any one of the phases, the current reduction process is performed by turning on the lower arm switch of a phase other than the lower arm switch in which the short circuit failure has occurred.

9. the bypass switch (61) electrically connects the positive electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit when turned on, and electrically disconnects the positive electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit when turned off; The power conversion device according to claim 1 , wherein the connection path electrically connects the armature winding and a negative electrode terminal of the first power storage unit.

10. The control device includes: The power conversion device according to claim 9, wherein when it is determined that a short circuit fault has occurred in the upper arm switch of any one of the phases, the current reduction process is performed by turning on the lower arm switch of a phase other than the upper arm switch in which the short circuit fault has occurred.

11. A motor-side switch (71) is provided in the connection path, The control device includes: performing the switching control in a state where the inter-storage unit switch is turned off and the bypass switch and the motor-side switch are turned on; The power conversion device according to claim 10 , wherein in the current reduction process, the lower arm switch of a phase different from that of the upper arm switch in which a short circuit has occurred is turned on, and then the motor side switch is turned off.

12. the motor-side switch is a first motor-side switch, a neutral capacitor (75) electrically connecting the high potential side path and the connection path; a second motor-side switch (72) provided in the connection path on the second storage unit side relative to a connection point with the neutral point capacitor; Equipped with The power conversion device according to claim 11 , wherein the control device, in the current reduction process, turns off the first motor side switch and then turns off the second motor side switch.

13. the inverter is a three-phase inverter, The power conversion device according to any one of claims 10 to 12, wherein the control device turns on the lower arm switches of two phases different from the upper arm switch in which a short circuit failure has occurred in the current reduction process.

14. A low-side fuse (42) is provided; the low potential side fuse electrically connects a negative electrode terminal of the second power storage unit and the low potential side path, or electrically connects the connection path and a positive electrode terminal of the second power storage unit, The control device includes: The power conversion device according to claim 9, wherein when it is determined that a short circuit fault has occurred in the upper arm switch of any one of the phases, the current reduction process is performed by turning on the lower arm switch of the same phase as the upper arm switch in which the short circuit fault has occurred.

15. An inverter (20) having upper and lower arm switches (SUH to SWL) for multiple phases; a motor (10) having an armature winding (11U to 11W) 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; A computer (101); A program applied to a power conversion device comprising: The power conversion device is a high potential side path (22H) electrically connecting a positive terminal of the first storage unit (31) and a high potential side terminal of the upper arm switch; a low potential side path (22L) electrically connecting a negative terminal of the second storage unit (32) and a low potential side terminal of the lower arm switch; a connection path (73) electrically connecting the negative terminal of the first storage unit or the positive terminal of the second storage unit to the armature winding; an inter-storage unit switch (50) that, when turned on, electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit, and, when turned off, electrically disconnects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a bypass switch (60, 61) that electrically connects negative electrode terminals of the first power storage unit and the second power storage unit to each other and electrically connects positive electrode terminals of the first power storage unit and the second power storage unit to each other; Equipped with The computer includes: a process of performing switching control of a target switch, which is at least one of the upper arm switch and the lower arm switch, so as to pass a current through the connection path while turning off the inter-storage unit switch and turning on the bypass switch; A process of determining whether or not a short circuit fault has occurred in at least one of the upper and lower arm switches; a current reduction process for reducing a current flowing through the connection path when it is determined that the short circuit fault has occurred; A program to execute.

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