Power conversion device and program

Abstract

This power conversion device comprises: an inverter (20); a motor (10) that has an armature winding (11); an inter-power-storage-unit switch (40) that is provided to an inter-power-storage-unit electrical path (24) which electrically connects a negative electrode terminal of a first power storage unit (31) and a positive electrode terminal of a second power storage unit (32); bypass switches (50, 51); motor-side electrical paths (25-28) that electrically connect the armature winding and the inter-power-storage-unit electrical path; and a control unit (100). When it is determined that there is a request for power transmission between the first power storage unit and the second power storage unit, the control unit controls transmission of power between the first power storage unit and the second power storage unit by switching of the inverter, with the operation mode of the inter-power-storage-unit switch and the bypass switch being set to a first mode for turning on the inter-power-storage-unit switch and turning off the bypass switch or a second mode for turning off the inter-power-storage-unit switch and turning on the bypass switch.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2022-144022, filed on September 9, 2022, the contents of which are incorporated herein by reference. [Technical Field]

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

[0003] As described in Patent Document 1, a conventional in-vehicle system is known that includes a motor, an inverter electrically connected to an armature winding of the motor, and first and second power storage units. This system includes a relay for switching the connection state of the first and second power storage units between a series connection state and a parallel connection state. This allows the first and second power storage units to be charged using either an external charger with a charging voltage of 400 V or an external charger with a charging voltage of 800 V. Furthermore, when an external charger with a charging voltage of 400 V is used, the first and second power storage units are connected in parallel, allowing the first and second power storage units to be charged by lowering the system voltage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6930306 Summary of the Invention

[0005] There is a demand for a new power conversion device that can transfer power between the first power storage unit and the second power storage unit.

[0006] A primary object of the present disclosure is to provide a power conversion device and a program that are capable of transmitting power between a first power storage unit and a second power storage unit.

[0007] The present disclosure provides a high-potential side electrical path electrically connectable to a positive electrode terminal of a first power storage unit; a low-potential side electrical path electrically connectable to a negative electrode terminal of the second power storage unit; an inverter having an upper arm switch electrically connected to the high potential side electrical path and a lower arm switch electrically connected to the low potential side electrical path; a motor having an armature winding electrically connected to a connection point of the upper arm switch and the lower arm switch via a conductive member; In a power conversion device comprising: an inter-power storage unit switch provided in an inter-power storage unit electrical path that electrically connects a negative electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit; a bypass switch that electrically connects at least one of the negative electrode terminals of the first power storage unit and the second power storage unit and the positive electrode terminals of the first power storage unit and the second power storage unit; and a motor-side electrical path electrically connecting the armature winding or the conductive member to the electrical path between the power storage units; A control unit; Equipped with The control unit determining whether there is a request for power transmission between the first power storage unit and the second power storage unit; When it is determined that there is a power transmission request, the operation modes of the inter-storage unit switch and the bypass switch are set to a first mode in which the inter-storage unit switch is turned on and the bypass switch is turned off, or a second mode in which the inter-storage unit switch is turned off and the bypass switch is turned on, and power transmission between the first power storage unit and the second power storage unit is controlled by switching the inverter.

[0008] By setting the operation modes of the inter-energy storage unit switch and the bypass switch to the first mode or the second mode, a circuit is configured that allows power to be transferred between the first and second energy storage units via the inverter and the armature winding. By switching the inverter in the first or second mode, power can be transferred between the first and second energy storage units. Furthermore, the configuration of the motor and the inverter can be reused for power transfer. This makes it possible to provide a power conversion device with a simplified configuration for transferring power between the first and second energy storage units. [Brief explanation of the drawings]

[0009] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: [Figure 1] FIG. 1 is a diagram showing the overall configuration of a system according to a first embodiment; [Figure 2] FIG. 2 is a flowchart showing the procedure of the power transmission control process; [Figure 3] FIG. 3 is a diagram illustrating a specific example of a power transmission request; [Figure 4] FIG. 4 is a diagram showing switch operation modes in a high-voltage charging mode; [Figure 5] FIG. 5 is a diagram showing switch operation modes in a high-voltage charging mode; [Figure 6] FIG. 6 is a diagram showing an equivalent circuit in a high-voltage charging mode; [Figure 7] FIG. 7 is a diagram showing switch operation modes in a low-voltage charging mode; [Figure 8] FIG. 8 is a diagram showing switch operation modes in a low-voltage charging mode; [Figure 9] FIG. 9 is a diagram showing an equivalent circuit in a low-voltage charging mode; [Figure 10] FIG. 10 is a diagram showing the overall configuration of a system according to the second embodiment; [Figure 11]FIG. 11 is a diagram illustrating the overall configuration of a system according to a modified example of the second embodiment; [Figure 12] FIG. 12 is a diagram illustrating the overall configuration of a system according to a modified example of the second embodiment; [Figure 13] FIG. 13 is a diagram illustrating the overall configuration of a system according to a modified example of the second embodiment; [Figure 14] FIG. 14 is a diagram showing the overall configuration of a system according to the third embodiment; [Figure 15] FIG. 15 is a time chart showing the switch abnormality diagnosis process. [Figure 16] FIG. 16 is a time chart showing the switch abnormality diagnosis process. [Figure 17] FIG. 17 is a time chart showing the switch abnormality diagnosis process. [Figure 18] FIG. 18 is a diagram illustrating the overall configuration of a system according to a modification of the third embodiment; [Figure 19] FIG. 19 is a diagram showing switch operation modes when precharging with the first storage battery; [Figure 20] FIG. 20 is a diagram showing switch operation modes when precharging with a second storage battery; [Figure 21] FIG. 21 is a diagram illustrating the overall configuration of a system according to a modification of the third embodiment; [Figure 22] FIG. 22 is a diagram showing switch operation modes when precharging with the first storage battery; [Figure 23] FIG. 23 is a diagram showing the overall configuration of a system according to a fourth embodiment; [Figure 24] FIG. 24 is a diagram showing the overall configuration of a system according to a fifth embodiment; [Figure 25] FIG. 25 is a diagram showing switch operation modes in a high-voltage charging mode; [Figure 26] FIG. 26 is a diagram showing switch operation modes in a low-voltage charging mode; [Figure 27] FIG. 27 is a diagram showing the overall configuration of a system according to the sixth embodiment; [Figure 28]FIG. 28 is a diagram showing the overall configuration of a system according to the seventh embodiment; [Figure 29] FIG. 29 is a diagram showing the overall configuration of a system according to another embodiment; [Figure 30] FIG. 30 is a diagram showing the overall configuration of a system according to another embodiment; [Figure 31] FIG. 31 is a diagram showing the overall configuration of a system according to another embodiment; [Figure 32] FIG. 32 is a diagram showing switch operation modes in a low-voltage charging mode; [Figure 33] FIG. 33 is a diagram showing the overall configuration of a system according to another embodiment; [Figure 34] FIG. 34 is a diagram showing the overall configuration of a system according to another embodiment; [Figure 35] FIG. 35 is a flowchart showing the procedure of the power transmission control process according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0011] First Embodiment A first embodiment of a power conversion device according to the present disclosure will be described below 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.

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

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

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

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

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

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

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

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

[0020] The power conversion device includes an inter-battery switch 40, an inter-negative electrode bypass switch 50, and a motor-side switch 60 as switches for switching the connection mode of the first storage battery 31 and the second storage battery 32 to an external charger. In this embodiment, the inter-battery switch 40, the inter-negative electrode bypass switch 50, and the motor-side switch 60 are mechanical relays. When turned off, the inter-battery switch 40, the inter-negative electrode bypass switch 50, and the motor-side switch 60 block bidirectional current flow, and when turned on, allow bidirectional current flow. Note that the inter-battery switch 40, the inter-negative electrode bypass switch 50, and the motor-side switch 60 are not limited to mechanical relays and may be, for example, semiconductor switching elements.

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

[0022] The negative electrode bypass switch 50 connects the negative electrode terminal of the first storage battery 31 and the low potential side electrical path 22L. When the negative electrode bypass switch 50 is turned on, the negative electrode terminal of the first storage battery 31 and the negative electrode terminal of the second storage battery 32 are electrically connected. On the other hand, when the negative electrode bypass switch 50 is turned off, the negative electrode terminal of the first storage battery 31 and the negative electrode terminal of the second storage battery 32 are electrically disconnected.

[0023] The motor-side switch 60 is provided on a motor-side electrical path 25 that connects the second storage battery 32 side of the inter-battery switch 40 of the inter-battery electrical path 24 with the neutral point of the armature winding 11. When the motor-side switch 60 is turned on, the neutral point of the armature winding 11 is electrically connected to the positive terminal of the second storage battery 32. When the motor-side switch 60 is turned off, the neutral point of the armature winding 11 is electrically disconnected from the positive terminal of the second storage battery 32.

[0024] The operation modes of the inter-battery switch 40, the negative pole bypass switch 50, and the motor-side switch 60 can be selected between a series neutral mode (corresponding to a "first mode") and a motor-via parallel mode (corresponding to a "second mode"). The series neutral mode is a mode in which the inter-battery switch 40 and the motor-side switch 60 are turned on and the negative pole bypass switch 50 is turned off (see FIG. 4). The series neutral mode is used, for example, when the first and second storage batteries 31, 32 are externally charged by a high-voltage charger 200. The motor-via parallel mode is a mode in which the inter-battery switch 40 is turned off and the negative pole bypass switch 50 and the motor-side switch 60 are turned on (see FIG. 7). The motor-via parallel mode is used, for example, when the first storage battery 31 is externally charged by a low-voltage charger 210.

[0025] The power conversion device includes a first voltage sensor 71 that detects the terminal voltage of the first storage battery 31 and a second voltage sensor 72 that detects the terminal voltage of the second storage battery 32. The power conversion device also includes a first current sensor 73 that detects the current flowing through the first storage battery 31 and a second current sensor 74 that detects the current flowing through the second storage battery 32. The first current sensor 73 is provided on an electrical path connecting the positive terminal of the first storage battery 31 and the high-potential side electrical path 22H. The second current sensor 74 is provided on an electrical path connecting the negative terminal of the second storage battery 32 and the low-potential side electrical path 22L. The power conversion device also includes a first temperature sensor 75 that detects the temperature of the first storage battery 31 and a second temperature sensor 76 that detects the temperature of the second storage battery 32. The power conversion device also includes other sensors, such as a rotation angle sensor that detects the rotation angle (electrical angle) of the rotor and phase current sensors that detect phase currents flowing through the armature windings 11 of each phase.

[0026] The detected values of each sensor are input to a control device 100 (corresponding to a "controller") included in the power conversion device. The control device 100 is mainly configured with a microcomputer 101, which includes a CPU. The functions provided by the microcomputer 101 can be provided by software recorded in a physical memory device and a computer that executes the software, by software alone, by hardware alone, or a combination thereof. For example, when the microcomputer 101 is provided by a hardware electronic circuit, the function can be provided by a digital circuit including multiple logic circuits or an analog circuit. For example, the microcomputer 101 executes a program stored in a non-transitory tangible storage medium that serves as a memory unit included in the microcomputer 101. The program includes, for example, a program for the processing shown in FIG. 2 (described later). Execution of the program results in the execution of a method corresponding to the program. The memory unit is, for example, a non-volatile memory. The program stored in the memory unit can be updated via a communication network such as the Internet, for example, via OTA (Over The Air) or the like.

[0027] The control device 100 performs switching control of the switches SWH and SWL constituting the inverter 20 to feedback-control the control variable of the motor 10 to a target value based on the detection values of each sensor. The control variable is, for example, torque. In each phase, the upper arm switch SWH and the lower arm switch SWL are alternately turned on. This feedback control transmits the rotational power of the rotor to the drive wheels of the vehicle CA, causing the vehicle CA to move.

[0028] The positive electrode connection portion of the high-potential side electrical path 22H and the negative electrode connection portion of the low-potential side electrical path 22L are interfaces for connection to an external charger. In this embodiment, the external charger is a high-voltage charger 200 or a low-voltage charger 210 (see FIGS. 4 and 7). The charging voltage of the high-voltage charger 200 is approximately the same as the inter-terminal voltage (specifically, the rated voltage) of the series-connected assembly of the first and second storage batteries 31 and 32, for example, 800 V. The charging voltage of the low-voltage charger 210 is lower than the rated voltage of the series-connected assembly of the first and second storage batteries 31 and 32, for example, 400 V. For example, when a user or an operator connects an external charger to each connection portion and charges the first and second storage batteries 31 and 32 using the external charger, the high-potential side charging switch DCRH and the low-potential side charging switch DCRL are switched on by the control device 100.

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

[0030] Next, a power transmission control process between the first and second storage batteries 31, 32, including a charging process using an external charger, will be described with reference to Fig. 2. This process is executed by the control device 100. In this embodiment, it is assumed that the process shown in Fig. 2 is executed while the vehicle CA is stopped (for example, while parked).

[0031] In step S10, it is determined whether or not there is a power transmission request. In this embodiment, as shown in Fig. 3, it is determined that there is a power transmission request when any one of the conditions (a) to (e) is met.

[0032] (a) The condition that there is a request for charging using an external charger.

[0033] If it is determined that there is a request for charging by an external charger, it is also determined whether the external charger to be used for charging is the high-voltage charger 200 or the low-voltage charger 210.

[0034] (b) The condition that the absolute value of the difference between the terminal voltage of the first storage battery 31 detected by the first voltage sensor 71 (hereinafter referred to as the first detected voltage VA) and the terminal voltage of the second storage battery 32 detected by the second voltage sensor 72 (hereinafter referred to as the second detected voltage VB) exceeds the potential threshold value Vth.

[0035] If the condition (b) is met, it is determined that there is a request to equalize the terminal voltages of the first and second storage batteries 31, 32, and a process is performed in step S22, etc., described below, to transfer power between the first storage battery 31 and the second storage battery 32 so as to reduce the difference between the terminal voltage of the first storage battery 31 and the terminal voltage of the second storage battery 32. (c) The condition that the absolute value of the difference between the storage rate SOCA of the first storage battery 31 and the storage rate SOCB of the second storage battery 32 exceeds the charging threshold Sth.

[0036] If the condition (c) is met, it is determined that there is a request to equalize the state of charge (SOC) of the first and second storage batteries 31, 32, and a process is performed in step S22 or the like to transfer power between the first storage battery 31 and the second storage battery 32 so as to reduce the difference in the state of charge between the first storage battery 31 and the second storage battery 32. Note that, for example, the first state of charge SOCA may be calculated based on the detection values of the first voltage sensor 71 and the first current sensor 73, and the second state of charge SOCB may be calculated based on the detection values of the second voltage sensor 72 and the second current sensor 74.

[0037] (d) The condition that the battery temperature Tbat is less than the target temperature Tth (corresponding to the "temperature threshold").

[0038] If the condition (d) is met, it is determined that there is a temperature increase request for the first and second storage batteries 31, 32, and temperature increase control is performed in step S22, etc. to increase the temperatures of the first and second storage batteries 31, 32 so as to bring out the performance of the first and second storage batteries 31, 32. The battery temperature Tbat may be set to, for example, the lower of the temperature of the first storage battery 31 detected by the first temperature sensor 75 (hereinafter referred to as the first detected temperature TA) and the temperature of the second storage battery 32 detected by the second temperature sensor 76 (hereinafter referred to as the second detected temperature TB).

[0039] (e) A condition that there is a request to change the vehicle control mode.

[0040] The vehicle control mode is, for example, a parking mode or a travel preparation mode in which the inter-battery switch 40 is turned on to prepare the vehicle CA for travel. For example, if the current vehicle control mode is the parking mode and the next vehicle control mode is the travel preparation mode, it may be desirable to adjust the charge rates or voltages of the first and second storage batteries 31, 32 prior to the travel preparation mode. Condition (e) is set in preparation for such a case.

[0041] 2, if it is determined in step S10 that there is a power transmission request, the process proceeds to step S11. In step S11, information on the current vehicle control mode and information on the next vehicle control mode to which the vehicle will be transitioned after the power transmission control process is completed are acquired.

[0042] In the next step S12, it is determined whether or not the operation modes of the inter-battery switch 40, the negative-electrode bypass switch 50, and the motor-side switch 60 can be switched to the motor-via parallel mode. Specifically, if it is determined that the value obtained by subtracting the first detected voltage VA from the second detected voltage VB is equal to or less than the determination threshold value ΔVjde (>0), it is determined that the operation mode can be switched to the motor-via parallel mode.

[0043] If the voltage across the second storage battery 32 is too high relative to the voltage across the first storage battery 31, when the operation modes of the inter-battery switch 40, the negative pole bypass switch 50, and the motor-side switch 60 are switched to the motor-through parallel mode, a phenomenon occurs in which current flows from the second storage battery 32 to the first storage battery 31 via the motor-side electrical path 25, the armature winding 11, the upper-arm diode DH connected in anti-parallel to the upper-arm switch SWH, and the high-potential side electrical path 22H (see FIG. 7). In this case, the reliability of the power conversion device and the storage batteries 31 and 32 may be reduced.

[0044] Therefore, the processing of step S12 is provided to suppress the occurrence of the phenomenon in which current flows from the second storage battery 32 to the first storage battery 31 via the motor 10 and the inverter 20, or to reduce the amount of current that flows even if this phenomenon does occur.

[0045] The determination threshold ΔVjde may be set to a voltage difference between the first storage battery 31 and the second storage battery 32 such that the maximum value and steady-state value of the inrush current determined from the relationship between "the impedance of the current path existing between the first storage battery 31 and the second storage battery 32 (specifically, for example, the impedance of the first and second storage batteries 31, 32, the impedance of the inverter 20 and the armature winding 11, and the forward impedance of the diode of the inverter 20)" and "the voltage difference between the first storage battery 31 and the second storage battery 32" are equal to or less than an allowable value when the operation mode is set to the motor-mediated parallel mode. Here, the allowable value is, for example, the maximum current that components on the current path can safely withstand.

[0046] The determination threshold ΔVjde is a value smaller than the rated voltage of each of the storage batteries 31, 32. The determination threshold ΔVjde is set, for example, to a value equal to or less than 1 / 10, 1 / 20, 1 / 50, or 1 / 100 of the lower of the rated voltages of the storage batteries 31, 32. A situation in which the second detection voltage VB and the first detection voltage VA differ significantly may occur, for example, in the following cases (1) to (3).

[0047] (1) When the rated voltages of the battery cells constituting the storage batteries 31, 32 are the same, the number of battery cells constituting the first storage battery 31 is different from the number of battery cells constituting the second storage battery 32.

[0048] (2) In a configuration in which the storage batteries 31, 32 have the same number of battery cells, the types of the storage batteries 31, 32 are different and the rated voltages of the battery cells of the storage batteries 31, 32 are different.

[0049] (3) The storage batteries 31, 32 have different numbers of battery cells, and the types of the storage batteries 31, 32 are different, so that the rated voltages of the battery cells of the storage batteries 31, 32 are different.

[0050] If it is determined in step S12 that the operation mode can be switched to the motor-via parallel mode, the system permits the operation mode to be switched to the motor-via parallel mode, and the system proceeds to step S13. In step S13, it is determined whether the external charger connected to each connection part of each electrical path 22H, 22L is the high-voltage charger 200. If the condition (a) is met in step S10 and the external charger is the high-voltage charger 200, an affirmative determination is made in step S13.

[0051] If it is determined in step S13 that the external charger is the high-voltage charger 200, the process proceeds to step S14, where the operation mode is switched to a series neutral point mode in which the inter-battery switch 40 and the motor-side switch 60 are turned on and the inter-negative pole bypass switch 50 is turned off, as shown in FIG. 4.

[0052] In the following step S15, with the main switches SMRH and SMRL and the charging switches DCRH and DCRL turned on, a high-voltage charging mode is performed in which the first storage battery 31 and the second storage battery 32 are charged by the high-voltage charger 200 based on the detected values of the first and second current sensors 73 and 74 and the first and second voltage sensors 71 and 72. In this mode, as shown in Fig. 4, a current flows through a closed circuit including the high-voltage charger 200, the high-potential side electrical path 22H, the first storage battery 31, the inter-battery switch 40, the second storage battery 32, and the low-potential side electrical path 22L, and the first storage battery 31 and the second storage battery 32 are charged in a series-connected state. Note that the main switches SMRH and SMRL are not shown in Fig. 4.

[0053] In the high-voltage charging mode, the charging power of the first storage battery 31 and the second storage battery 32 can be individually adjusted based on the detection values of the first and second current sensors 73, 74 and the first and second voltage sensors 71, 72. This adjustment can be performed by switching at least one phase of the inverter 20 while charging each of the storage batteries 31, 32 with the high-voltage charger 200. As an example of switching, Fig. 4 shows that the upper arm switch SWH is turned on and the lower arm switch SWL is turned off for one phase, and Fig. 5 shows that the upper arm switch SWH is turned off and the lower arm switch SWL is turned on for one phase. That is, in this switching, the upper and lower arm switches SWH and SWL of the same phase are alternately turned on.

[0054] As shown in Fig. 6, in addition to the loop LPH of the charging current from the high-voltage charger 200, current loops LPA1 and LPA2 appear due to switching. This allows the charging power of the first storage battery 31 and the second storage battery 32 to be adjusted individually. Here, the charging power of the first storage battery 31 and the second storage battery 32 can be adjusted by adjusting the duty ratio (Ton / Tsw), which is the ratio of the on-period Ton of the upper arm switch SWH or the lower arm switch SWL to one switching period Tsw. In this adjustment, the charging power of either the first or second storage battery 31, 32 can also be set to zero.

[0055] For example, the charging power of the high-voltage charger 200 is set to 100 kW, and the inverter 20 is switched so as to continuously send 10 kW of power from the first storage battery 31 to the second storage battery 32 via the inverter 20 and the armature winding 11. If the battery characteristics, SOC, and inter-terminal voltage of the first storage battery 31 and the second storage battery 32 are the same, the charging power of the first storage battery 31 will be 40 kW, and the charging power of the second storage battery 32 will be 60 kW.

[0056] When it is desired to increase the charging power of the second storage battery 32 compared to the first storage battery 31, the inverter 20 is switched so as to transmit power from the first storage battery 31 to the second storage battery 32. Specifically, the inverter 20 is switched to alternately turn on the upper and lower arm switches SWH, SWL in at least one phase, or to repeatedly turn on and off the upper arm switch SWH in at least one phase while turning off the lower arm switches SWL in all phases.

[0057] When it is desired to make the charging power of the first storage battery 31 greater than that of the second storage battery 32, the inverter 20 is switched so as to transmit power from the second storage battery 32 to the first storage battery 31. Specifically, the inverter 20 is switched to alternately turn on the upper and lower arm switches SWH and SWL in at least one phase, or to repeatedly turn on and off the lower arm switch SWL in at least one phase while turning off the upper arm switches SWH in all phases.

[0058] When performing the above-mentioned switching to individually adjust the charging power, the switching may be performed based on the detected value of the electrical angle so that the torque of the motor 10 is 0 or a value close to 0 (specifically, for example, the q-axis current flowing through the armature winding 11 is 0 or a value close to 0).

[0059] Being able to individually adjust the charging power for the first and second storage batteries 31, 32 is advantageous, for example, when the materials constituting the first and second storage batteries 31, 32 are different and the charging power (e.g., rated charging power) of the first and second storage batteries 31, 32 is different.

[0060] In the high-voltage charging mode, while the first storage battery 31 and the second storage battery 32 are being charged by the high-voltage charger 200, the following processing can be performed by switching at least one phase of the inverter 20.

[0061] The first process is a voltage equalization process for equalizing the first detection voltage VA and the second detection voltage VB. This process may be executed when the conditions (a) and (b) are met in step S10. In this embodiment, the detection voltages VA and VB correspond to "capacity parameters."

[0062] The voltage equalization process in step S15 is a process in which, with the operation mode set to the series neutral point mode, the inverter 20 is switched until the difference between the first detected voltage VA and the second detected voltage VB becomes equal to or less than the potential threshold Vth. This allows the voltages of the first and second storage batteries 31, 32 to be equalized while the high-voltage charger 200 externally charges the first and second storage batteries 31, 32.

[0063] The second process is a capacity equalization process that equalizes the storage rate SOCA of the first storage battery 31 and the storage rate SOCB of the second storage battery 32. This process may be executed when the conditions (a) and (c) are met in step S10. In this embodiment, the storage rates SOCA and SOCB correspond to "capacity parameters."

[0064] The capacity equalization process in step S15 is a process of switching the inverter 20 in the series neutral point mode until the difference between the storage rate SOCA of the first storage battery 31 and the storage rate SOCB of the second storage battery 32 becomes equal to or less than the charging threshold value Sth. This allows the storage rates of the first and second storage batteries 31, 32 to be equalized while the high-voltage charger 200 externally charges the first and second storage batteries 31, 32.

[0065] In the capacity equalization process, the capacity [Ah] of the storage battery, which has a positive correlation with the charging rate, may be used instead of the charging rate.

[0066] The third process is a temperature increase control process for increasing the temperatures of the first and second storage batteries 31, 32. This process may be executed when the conditions (a) and (d) are met in step S10.

[0067] The temperature rise control process in step S15 is a process in which, with the operation mode set to the series neutral point mode, the inverter 20 is switched so that an AC charge / discharge current flows between the first storage battery 31 and the second storage battery 32 via the armature winding 11 and the inverter 20 until the battery temperature Tbat (corresponding to the "temperature parameter") reaches the target temperature Tth. The switching here is performed by alternately turning on the upper and lower arm switches SWH, SWL in at least one phase.

[0068] The temperature increase control process can promote heat generation due to the internal resistance of the battery, thereby increasing the temperature of each of the storage batteries 31, 32. This increases the maximum charging power of each of the storage batteries 31, 32, and shortens the time required for external charging of each of the storage batteries 31, 32 while the vehicle CA is parked.

[0069] The above-described voltage equalization process may be performed prior to the temperature rise control process. By starting the temperature rise control process with the difference between the first detected voltage VA and the second detected voltage VB small (specifically, for example, with the difference equalized to or less than the potential threshold Vth), the temperature rise rates of the batteries 31 and 32 are made as equal as possible.

[0070] That is, when the temperature rise control process is performed, the discharge power or charge power of the first storage battery 31 is equal to the charge power or discharge power of the second storage battery 32. Here, for example, assume that the temperature rise control process is performed when the terminal voltage of the first storage battery 31 is 400 V and the terminal voltage of the second storage battery 32 is 100 V. In this case, based on the above-described principle that the discharge power and the charge power are equal, if it is desired to repeatedly charge and discharge, for example, 40,000 kW of power, a maximum charge / discharge current of 100 A flows through the first storage battery 31, and a maximum charge / discharge current of 400 A flows through the second storage battery 32. The rate of battery temperature rise depends on Joule heat generated in the battery, and Joule heat is proportional to the square of the current. Therefore, the rate of temperature rise of the second storage battery 32 becomes excessively higher than the rate of temperature rise of the first storage battery 31. In order to avoid the occurrence of such a problem, a voltage equalization process is performed prior to the temperature increase control process so that the charge / discharge currents flowing through the first and second storage batteries 31, 32 are as equal as possible.

[0071] Incidentally, in the temperature rise control process, instead of the battery temperature Tbat, for example, the sensor detection value of the temperature of the inverter 20, the temperature of the motor 10, or the temperature of the cooling water for the inverter 20 and the motor 10, which are positively correlated with the battery temperature Tbat, may be used.

[0072] In step S15, if individual charging power setting or voltage equalization processing is not performed, the motor-side switch 60 may be turned off. In this case, the charging current of the high-voltage charger 200 can be prevented from flowing to the inverter 20 and the armature winding 11.

[0073] Returning to the explanation of FIG. 2, after the process of step S15 is completed, the process proceeds to step S16, where the vehicle control mode is shifted to the next vehicle control mode.

[0074] On the other hand, if it is determined in step S13 that the external charger is not the high-voltage charger 200, the process proceeds to step S17, where it is determined whether the connected external charger is the low-voltage charger 210. If the condition (a) is met in step S10 and the external charger is the low-voltage charger 210, an affirmative determination is made in step S17.

[0075] If it is determined in step S17 that the external charger is the low-voltage charger 210, the process proceeds to step S18, where the operation mode is switched to a motor-via parallel mode in which the inter-battery switch 40 is turned off and the inter-negative pole bypass switch 50 and the motor-side switch 60 are turned on, as shown in Fig. 7. In this case, the system voltage is reduced to a voltage equivalent to the charging voltage of the low-voltage charger 210, and a ground fault countermeasure can be taken when charging using the low-voltage charger 210.

[0076] In the following step S19, with the main switches SMRH and SMRL and the charging switches DCRH and DCRL turned on, a low-voltage charging mode is performed in which the first storage battery 31 is charged by the low-voltage charger 210. In this mode, as shown in Fig. 7 , a current flows through a closed circuit including the low-voltage charger 210, the high-potential side electrical path 22H, the first storage battery 31, the negative electrode bypass switch 50, and the low-potential side electrical path 22L, and the first storage battery 31 is charged by the low-voltage charger 210.

[0077] In the low-voltage charging mode, the charging power of the first storage battery 31 and the second storage battery 32 can be individually adjusted based on the detected values of the first and second current sensors 73, 74 and the first and second voltage sensors 71, 72. This adjustment can be performed by repeatedly switching the upper arm switch SWH for at least one phase in the inverter 20 on and off while the first storage battery 31 is being charged by the low-voltage charger 210. FIG. 7 shows, as an example of switching, that the upper arm switch SWH is turned on and the lower arm switch SWL is turned off for one phase, and FIG. 8 shows that the upper arm switch SWH is turned off and the lower arm switch SWL is turned on for one phase. In this adjustment, the charging power of either the first or second storage battery 31, 32 can also be set to zero.

[0078] 9, in addition to the loop LPL of the charging current from the low-voltage charger 210, a current loop LPB appears due to switching. This makes it possible to individually adjust the charging power of the first storage battery 31 and the second storage battery 32. Here, the charging power of the first storage battery 31 and the second storage battery 32 can be adjusted by adjusting the duty ratio (Ton / Tsw), which is the ratio of the on-period Ton of the upper arm switch SWH to one switching cycle Tsw.

[0079] Even in the low-voltage charging mode, the first storage battery 31 is charged by the low-voltage charger 210, and at least one phase of the inverter 20 is switched to perform voltage equalization, capacity equalization, and temperature rise control.

[0080] The voltage equalization process in step S19 is a process of switching the inverter 20 until the difference between the first detected voltage VA and the second detected voltage VB becomes equal to or less than the potential threshold Vth when the operation mode is set to the motor-mediated parallel mode. As a result, the first storage battery 31 is externally charged by the low-voltage charger 210, while power is supplied from the first storage battery 31 to the second storage battery 32 via the inverter 20 and the armature winding 11, thereby enabling voltage equalization of the first and second storage batteries 31, 32.

[0081] The capacity equalization process in step S19 is a process of switching the inverter 20 in the motor-mediated parallel operation mode until the difference between the storage rate SOCA of the first storage battery 31 and the storage rate SOCB of the second storage battery 32 becomes equal to or less than the charging threshold value Sth. This allows the storage rates of the first and second storage batteries 31, 32 to be equalized while the first storage battery 31 is externally charged by the low-voltage charger 210.

[0082] The temperature rise control process in step S19 is a process in which, with the operation mode set to the motor-mediated parallel mode, the inverter 20 is switched so that an AC charge / discharge current flows between the first storage battery 31 and the second storage battery 32 via the armature winding 11 and the inverter 20 until the battery temperature Tbat reaches the target temperature Tth. Note that the voltage equalization process described above may be performed prior to the temperature rise control process.

[0083] According to the low-voltage charging mode, the first storage battery 31 can be directly charged by the low-voltage charger 210, and the second storage battery 32 can be charged via the inverter 20 and the armature winding 11. Furthermore, even if the first and second storage batteries 31 and 32 have different rated voltages, or even if the first and second storage batteries 31 and 32 have the same rated voltage but different actual terminal voltages, the first and second storage batteries 31 and 32 can be charged simultaneously without an additional power conversion circuit.

[0084] Returning to the explanation of FIG. 2, after the process of step S19 is completed, the process proceeds to step S16, where the vehicle control mode is shifted to the next vehicle control mode.

[0085] If a negative determination is made in step S17, the process proceeds to step S20. If the condition (a) is not met in step S10 and at least one of the conditions (b) to (e) is met, a negative determination is made in step S17.

[0086] In step S20, it is determined whether the operation mode to be selected when power transmission control is performed in step S22 is the series neutral point mode or the motor-via parallel mode. Here, the determination is made based on whether the total number of switching times of the inter-battery switch 40, the negative pole bypass switch 50, and the motor-side switch 60 from the current vehicle control mode to the next vehicle control mode via the power transmission control in step S22 is smaller: when the series neutral point mode is selected in power transmission control, or when the motor-via parallel mode is selected.

[0087] In detail, the first total number of switching times of the battery-to-battery switch 40, the negative-electrode bypass switch 50, and the motor-side switch 60 when transitioning from the current vehicle control mode to the next vehicle control mode via power transmission control in which the series neutral point mode is selected is calculated.

[0088] In addition, the second total number of switching times of the battery-to-battery switch 40, negative-electrode bypass switch 50, and motor-side switch 60 when transitioning from the current vehicle control mode to the next vehicle control mode via power transmission control that selects the motor-via parallel mode is calculated.

[0089] If the first total switching number is less than the second total switching number, proceed to step S23 to select the series neutral point mode, whereas if the second total switching number is less than the first total switching number, proceed to step S21 to select the motor-through parallel mode.

[0090] By performing the process of step S20, the progress of deterioration of the inter-battery switch 40, the negative electrode bypass switch 50, and the motor-side switch 60 can be suppressed.

[0091] In step S20, the total number of switching times of the inter-battery switch 40, the negative pole bypass switch 50, and the motor-side switch 60 when transitioning from the current vehicle control mode to power transmission control in which the series neutral point mode is selected may be calculated as the first total number of switching times. Also, in step S20, the total number of switching times of the inter-battery switch 40, the negative pole bypass switch 50, and the motor-side switch 60 when transitioning from the current vehicle control mode to power transmission control in which the motor-via-parallel mode is selected may be calculated as the second total number of switching times.

[0092] If the motor-via parallel mode is selected in step S20, the process proceeds to step S21, where the operation mode is changed to the motor-via parallel mode, and the voltage equalization process, capacity equalization process, or temperature rise control process is performed in step S22. Thereafter, the process proceeds to step S16.

[0093] On the other hand, if the series neutral point mode is selected in step S20, the process proceeds to step S23, where the operation mode is changed to the series neutral point mode, and the voltage equalization process, capacity equalization process, or temperature rise control process is performed in step S22. Thereafter, the process proceeds to step S16.

[0094] If it is determined in step S12 that the operation mode cannot be shifted to the motor-directed parallel mode, the operation mode is prohibited from being changed to the motor-directed parallel mode, and the process proceeds to step S24. In step S24, it is determined whether the external charger connected to each connection part of each electrical path 22H, 22L is the low-voltage charger 210. If the condition (a) is not met in step S10, and at least one of the conditions (b) to (e) is met, a negative determination is made in step S24, and the process proceeds to step S23. Then, with the operation mode set to the series neutral point mode, a voltage equalization process, a capacity equalization process, or a temperature rise control process is performed in step S22.

[0095] If the determination in step S24 is affirmative, the operation mode is made ready to be switched to the motor-via parallel mode, and the low-voltage charging mode in step S19 is performed.

[0096] Specifically, first, in step S25, the charging switches DCRH and DCRL are turned off, thereby electrically disconnecting the power converter from the external charger and ensuring the safety of the user or operator of the vehicle CA.

[0097] In the following step S26, the operation mode is changed to the series neutral point mode. In step S27, the upper arm switch SWH of at least one phase is repeatedly switched on and off, provided that the upper and lower arm switches SWH, SWL of the same phase are not simultaneously turned on, thereby transmitting power from the first storage battery 31 to the second storage battery 32 until the difference between the first detection voltage VA and the second detection voltage VB becomes equal to or less than the potential threshold Vth. Then, when it is determined that the difference between the first detection voltage VA and the second detection voltage VB becomes equal to or less than the potential threshold, the process proceeds to step S18, where the operation mode is changed to the motor-mediated parallel mode, and in step S19, the low-voltage charging mode is performed.

[0098] According to the present embodiment described above, it is possible to provide a power conversion device with a simplified configuration for properly charging the first and second storage batteries 31, 32.

[0099] Second Embodiment The second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, switching control of the inverter 20 is performed in the power transmission control process. In this case, a high-frequency current is generated due to the switching. In this embodiment, as shown in FIG. 10, the power conversion device is provided with a capacitor 90 that suppresses the high-frequency current generated due to the switching from flowing from the inverter 20 side to the second storage battery 32 and the low-voltage charger 210.

[0100] A portion of the low potential side electrical path 22L between the low potential side main switch SMRL and the low potential side charging switch DCRL is connected to the neutral point side of the motor side switch 60 in the motor side electrical path 25 via a series connection of a connection switch 91 and a capacitor 90. The connection switch 91 may be a mechanical relay or a semiconductor switching element.

[0101] The control device 100 turns off the connection switch 91 during switching control of the inverter 20 for running the vehicle CA. This makes it possible to suppress adverse effects on the control when the control amount of the motor 10 is controlled to the command value.

[0102] 2, the control device 100 turns on the connection switch 91. As a result, when a current flows through the motor-side electrical path 25, noise or ripple contained in the current flowing through the motor-side electrical path 25 can be passed to the capacitor 90.

[0103] According to the present embodiment described above, it is possible to prevent high-frequency current generated by switching from flowing from the inverter 20 side into the second storage battery 32 and the low-voltage charger 210 during the power transmission control process.

[0104] <Modification of the second embodiment> The capacitor 90 may be connected to the motor-side electrical path 25 side, and the connection switch 91 may be connected to the low-potential-side electrical path 22L side.

[0105] The connection switch 91 may be omitted. In other words, the motor-side electrical path 25 and the low-potential-side electrical path 22L may be constantly connected.

[0106] As shown in FIG. 11, a series connection of a connection switch 92 and a capacitor 90 may connect a portion of the motor-side electrical path 25 that is closer to the second storage battery 32 than the motor-side switch 60 to the low-potential-side electrical path 22L.

[0107] 11, the connection switch 92 may be omitted. That is, the motor-side electrical path 25 and the low-potential-side electrical path 22L may be constantly connected.

[0108] 12, a plurality of capacitors may be provided. More specifically, a connection switch 93 is provided on the motor-side electrical path 25 closer to the neutral point than the motor-side switch 60. A high-potential-side electrical path 22H is connected to a portion of the motor-side electrical path 25 between the motor-side switch 60 and the connection switch 93 via a first capacitor 93A, and a low-potential-side electrical path 22L is connected to the portion of the motor-side electrical path 25 between the motor-side switch 60 and the connection switch 93 via a second capacitor 93B.

[0109] In the configuration shown in FIG. 12, either the first capacitor 93A or the second capacitor 93B may be omitted.

[0110] As shown in FIG. 13, a first terminal of a connection switch 94 may be connected to a position on the motor-side electrical path 25 closer to the neutral point than the motor-side switch 60, and a first capacitor 93A and a second capacitor 93B may be connected to a second terminal of the connection switch 94.

[0111] <Third embodiment> The third embodiment will be described below with reference to the drawings, focusing on the differences from the second embodiment. In this embodiment, as shown in Fig. 14, a series connection of a precharge switch SP and a resistor 95 is connected in parallel to a low-side main switch SMRL. For convenience, the control device 100 and other components are not shown in Fig. 14.

[0112] The power conversion device includes a third voltage sensor 77A that detects the voltage across the terminals of capacitor 90 and a fourth voltage sensor 77B that detects the voltage across the terminals of smoothing capacitor 21. The detected values of third voltage sensor 77A and fourth voltage sensor 77B are input to control device 100.

[0113] Next, an economical switching sequence for each switch, including abnormality diagnosis (e.g., welding diagnosis) for each switch in the series neutral point mode, will be described using Figures 15 to 17. In Figures 15 to 17, Vcinv indicates the voltage across smoothing capacitor 21 detected by fourth voltage sensor 77B, and Vcb indicates the voltage across capacitor 90 detected by third voltage sensor 77A. The time charts of voltages Vcinv and Vcb shown in Figures 15 to 17 are for the case where no failure occurs in any switch. The hatched periods in Figures 15 to 17 indicate periods during which abnormality diagnosis can be performed.

[0114] In the explanations of Figures 15 to 17, an operation to turn on a switch is referred to as a switch on operation, and a state in which the switch is actually turned on by the on operation is referred to as the on state of the switch. An operation to turn off a switch is referred to as a switch off operation, and a state in which the switch is actually turned off by the off operation is referred to as the off state of the switch. A failure in which the switch remains in the off state even after an on operation is called an open switch failure, and a failure in which the switch remains in the on state even after an off operation is called a closed switch failure. Open and closed switch failures can occur not only due to an abnormality in the switch itself, but also, for example, due to an abnormality in the switch drive circuit.

[0115] First, FIG. 15 will be described.

[0116] At time t1, the main switches SWRH and SWRL, the precharge switch SP, the inter-battery switch 40, the negative electrode bypass switch 50, the motor-side switch 60, and the connection switch 93 are turned off.

[0117] At time t2, the control device 100 switches on the pre-charge switch SP. During the period from time t2 to t3, the control device 100 determines whether or not a closed fault has occurred in the motor-side switch 60 based on the voltage Vcb across the capacitor 90. More specifically, if the control device 100 determines that the voltage Vcb across the capacitor 90 does not increase, it determines that a closed fault has not occurred in the motor-side switch 60, and if the control device 100 determines that the voltage Vcb across the capacitor 90 increases, it determines that a closed fault has occurred in the motor-side switch 60.

[0118] At time t3, the control device 100 switches the high potential side main switch SMRH on. During the period from time t3 to t4, the control device 100 determines whether a closing fault has occurred in the inter-battery switch 40 and the negative electrode bypass switch 50 based on the inter-terminal voltage Vcinv of the smoothing capacitor 21. In more detail, if the control device 100 determines that the inter-terminal voltage Vcinv of the smoothing capacitor 21 does not increase, it determines that a closing fault has not occurred in the inter-battery switch 40 and the negative electrode bypass switch 50, and if it determines that the inter-terminal voltage Vcinv of the smoothing capacitor 21 increases, it determines that a closing fault has occurred in the inter-battery switch 40 and the negative electrode bypass switch 50.

[0119] At time t4, the control device 100 switches the connection switch 93 to the on position.

[0120] At time t5, the control device 100 turns on the motor-side switch 60. If no abnormality occurs in the switches, the voltages across the capacitor 90 and the smoothing capacitor 21 rise to the voltage VB across the second storage battery 32.

[0121] During the period from time t5 to t6, the control device 100 determines whether or not an open fault has occurred in the motor-side switch 60, based on the inter-terminal voltage Vcb of the capacitor 90. In more detail, if the control device 100 determines that the inter-terminal voltage Vcb of the capacitor 90 is increasing, it determines that an open fault has not occurred in the motor-side switch 60, and if it determines that the inter-terminal voltage Vcb of the capacitor 90 is not increasing, it determines that an open fault has occurred in the motor-side switch 60.

[0122] During the period from time t5 to t6, the control device 100 determines whether or not an open fault has occurred in the connection switch 93, based on the inter-terminal voltage Vcinv of the smoothing capacitor 21. In more detail, if the control device 100 determines that the inter-terminal voltage Vcinv of the smoothing capacitor 21 is increasing, it determines that an open fault has not occurred in the connection switch 93, and if it determines that the inter-terminal voltage Vcinv of the smoothing capacitor 21 is not increasing, it determines that an open fault has occurred in the connection switch 93.

[0123] During the period from time t5 to t6, the control device 100 determines whether or not a closing fault has occurred in the low potential side main switch SMRL based on a determination voltage, which is at least one of the inter-terminal voltage Vcinv of the smoothing capacitor 21 and the capacitor 90. More specifically, if the control device 100 determines that the rate of increase of the determination voltage is equivalent to the rate of increase of the determination voltage when the low potential side main switch SMRL is in the off state, it determines that a closing fault has not occurred in the low potential side main switch SMRL. On the other hand, if the control device 100 determines that the rate of increase of the determination voltage is higher than the rate of increase of the determination voltage when the low potential side main switch SMRL is in the off state, it determines that a closing fault has occurred in the low potential side main switch SMRL.

[0124] During the period from time t5 to t6, the control device 100 determines whether an open fault has occurred in the pre-charge switch SP based on a determination voltage, which is at least one of the inter-terminal voltage Vcinv of the smoothing capacitor 21 and the voltage of the capacitor 90. In more detail, if the control device 100 determines that the determination voltage is increasing, it determines that an open fault has not occurred in the pre-charge switch SP, and if it determines that the determination voltage is not increasing, it determines that an open fault has occurred in the pre-charge switch SP.

[0125] At time t6, the control device 100 turns on the inter-battery switch 40. If no abnormality occurs in any of the switches, the voltage across the smoothing capacitor 21 rises to the sum of the voltages across the first and second storage batteries 31, 32, "VA+VB." This completes the pre-charge.

[0126] During the period from time t6 to t7, the control device 100 determines whether or not an open fault has occurred in the high-side main switch SMRH and the inter-battery switch 40, based on the inter-terminal voltage Vcinv of the smoothing capacitor 21. In detail, if the control device 100 determines that the inter-terminal voltage Vcinv of the smoothing capacitor 21 is increasing, it determines that an open fault has not occurred in the high-side main switch SMRH and the inter-battery switch 40, and if it determines that the inter-terminal voltage Vcinv of the smoothing capacitor 21 is not increasing, it determines that an open fault has occurred in the high-side main switch SMRH and the inter-battery switch 40.

[0127] At time t7, the control device 100 switches on the low potential side main switch SMRL.

[0128] At time t8, the control device 100 switches the precharge switch SP to the OFF state, thereby completing the startup sequence.

[0129] The control device 100 performs the process shown in Fig. 2 during the period from time t8 to t9. During the period from time t8 to t9, the control device 100 determines whether an expected current is flowing based on the detection value of at least one current sensor provided in the power conversion device, thereby determining whether an open fault has occurred in the low potential side main switch SMRL.

[0130] At time t9, the control device 100 switches the high potential side main switch SMRH to the OFF position to start the termination sequence.

[0131] At time t10, the control device 100 switches off the motor-side switch 60. The control device 100 transfers charge from the capacitor 90 to the smoothing capacitor 21 by repeatedly switching on and off at least one phase of the lower arm switch SWL, thereby completing the discharge of the capacitor 90.

[0132] At time t11, the control device 100 switches the connection switch 93 to the OFF position. The control device 100 controls the switching of the upper and lower arm switches SWH and SWL to release charge from the smoothing capacitor 21, completing the discharge of the smoothing capacitor 21. At time t12, the control device 100 switches the low potential side main switch SMRL and the inter-battery switch 40 to the OFF position. Thereafter, the termination sequence ends at time t13.

[0133] During the period from time t11 to t12, the control device 100 determines whether or not a closing fault has occurred in the high potential side main switch SMRH and the pre-charge switch SP, based on the inter-terminal voltage Vcinv of the smoothing capacitor 21. In detail, if the control device 100 determines that the inter-terminal voltage Vcinv of the smoothing capacitor 21 decreases, it determines that a closing fault has not occurred in the high potential side main switch SMRH and the pre-charge switch SP, and if it determines that the inter-terminal voltage Vcinv of the smoothing capacitor 21 does not decrease, it determines that a closing fault has occurred in the high potential side main switch SMRH and the pre-charge switch SP.

[0134] In addition, the control device 100 may perform switching control of the inverter 20 so that power is supplied from the smoothing capacitor 21 to the capacitor 90 during the discharge period of the smoothing capacitor 21 from time t11 or before the discharge, and if it determines that the inter-terminal voltage Vcb of the capacitor 90 does not increase during that switching control period, it may determine that an open failure has occurred in the connection switch 93.

[0135] During the period from time t11 to t12, the control device 100 determines whether or not a close fault has occurred in the connection switch 93, based on the voltage Vcb across the capacitor 90. In more detail, if the control device 100 determines that the voltage Vcb across the capacitor 90 does not increase, it determines that a close fault has not occurred in the connection switch 93, and if the control device 100 determines that the voltage Vcb across the capacitor 90 increases, it determines that a close fault has occurred in the connection switch 93.

[0136] In the series neutral point mode, it is assumed that the negative pole-to-negative pole bypass switch 50 is in the OFF state. For this reason, in this embodiment, the presence or absence of an open circuit fault of the negative pole-to-negative pole bypass switch 50 is not diagnosed.

[0137] Next, FIG. 16 will be described.

[0138] At time t1, the main switches SWRH and SWRL, the precharge switch SP, the inter-battery switch 40, the negative electrode bypass switch 50, the motor-side switch 60, and the connection switch 93 are turned off.

[0139] At time t2, the control device 100 turns on the precharge switch SP. During the period from time t2 to t3, the control device 100 determines whether or not a closed fault has occurred in the motor-side switch 60 based on the inter-terminal voltage Vcb of the capacitor 90, similar to the period from time t2 to t3 in FIG.

[0140] At time t3, the control device 100 switches on the high potential side main switch SMRH. During the period from time t3 to t4, the control device 100 determines whether or not a closed fault has occurred in the inter-battery switch 40 and the negative electrode bypass switch 50 based on the inter-terminal voltage Vcinv of the smoothing capacitor 21, similar to the period from time t3 to t4 in Fig. 15 .

[0141] At time t4, the control device 100 turns on the inter-battery switch 40. If no abnormality occurs in any of the switches, the voltage across the smoothing capacitor 21 rises to the sum of the voltages across the first and second storage batteries 31, 32, "VA+VB." This completes the pre-charging of the smoothing capacitor 21.

[0142] During the period from time t4 to t5, the control device 100 determines whether or not an open fault has occurred in the high-side main switch SMRH, the pre-charge switch SP, and the inter-battery switch 40, based on the inter-terminal voltage Vcinv of the smoothing capacitor 21. In detail, if the control device 100 determines that the inter-terminal voltage Vcinv of the smoothing capacitor 21 will increase, it determines that an open fault has not occurred in the high-side main switch SMRH, the pre-charge switch SP, and the inter-battery switch 40, and if it determines that the inter-terminal voltage Vcinv will not increase, it determines that an open fault has occurred in at least one of the high-side main switch SMRH, the pre-charge switch SP, and the inter-battery switch 40.

[0143] During the period from time t4 to t5, the control device 100 determines whether or not a closing fault has occurred in the low-side main switch SMRL, based on the inter-terminal voltage Vcinv of the smoothing capacitor 21. More specifically, if the control device 100 determines that the rate of increase of the inter-terminal voltage Vcinv is equivalent to the rate of increase of the inter-terminal voltage Vcinv when the low-side main switch SMRL is in the off state, it determines that a closing fault has not occurred in the low-side main switch SMRL. On the other hand, if the control device 100 determines that the rate of increase of the inter-terminal voltage Vcinv is higher than the rate of increase of the inter-terminal voltage Vcinv when the low-side main switch SMRL is in the off state, it determines that a closing fault has occurred in the low-side main switch SMRL.

[0144] At time t5, the control device 100 turns on the connection switch 93. At time t6, the control device 100 turns on the motor-side switch 60. If no abnormality occurs in any of the switches, the voltage Vcb across the capacitor 90 rises to the voltage VB across the second storage battery 32.

[0145] During the period from time t5 to t6, similar to the period from time t5 to t6 in FIG. 15, the control device 100 determines whether an open fault has occurred in the motor-side switch 60 based on the inter-terminal voltage Vcb of the capacitor 90.

[0146] At time t7, the control device 100 switches the low-side main switch SMRL to the ON position. At time t8, the control device 100 switches the pre-charge switch SP to the OFF position. This ends the startup sequence.

[0147] The control device 100 performs the process shown in Fig. 2 during the period from time t8 to t9. During the period from time t8 to t9, the control device 100 determines whether an expected current is flowing based on the detection value of at least one current sensor provided in the power conversion device, thereby determining whether an open fault has occurred in the low potential side main switch SMRL and the connection switch 93.

[0148] At time t9, the control device 100 switches the high potential side main switch SMRH to the OFF position to start the termination sequence.

[0149] At time t10, the control device 100 switches off the motor-side switch 60. The control device 100 transfers charge from the capacitor 90 to the smoothing capacitor 21 by repeatedly switching on and off at least one phase of the lower arm switch SWL, thereby completing the discharge of the capacitor 90.

[0150] At time t11, the control device 100 switches the connection switch 93 to the OFF position. The control device 100 switches the upper and lower arm switches SWH and SWL to release charge from the smoothing capacitor 21, completing the discharge of the smoothing capacitor 21. At time t12, the control device 100 switches the low potential side main switch SMRL and the inter-battery switch 40 to the OFF position. Thereafter, the termination sequence ends at time t13.

[0151] During the period from time t11 to t12, similar to the period from time t11 to t12 in FIG. 15, the control device 100 determines whether or not a closing failure has occurred in the high-potential side main switch SMRH based on the inter-terminal voltage Vcinv of the smoothing capacitor 21, and determines whether or not a closing failure has occurred in the connection switch 93 based on the inter-terminal voltage Vcb of the capacitor 90.

[0152] In addition, similar to the processing of Figure 15, the control device 100 performs switching control of the inverter 20 so that power is supplied from the smoothing capacitor 21 to the capacitor 90 during the discharge period of the smoothing capacitor 21 from time t11 or before the discharge, and if it determines that the inter-terminal voltage Vcb of the capacitor 90 does not increase during that switching control period, it may determine that an open failure has occurred in the connection switch 93.

[0153] Next, FIG. 17 will be described.

[0154] The processing during the period from time t1 to t5 is the same as the processing during the period from time t1 to t5 in FIG.

[0155] During the period from time t5 to t7, the control device 100 performs processing to charge the capacitor 90 by switching control of the inverter 20. Here, the switching control is stopped before the inter-terminal voltage Vcb of the capacitor 90 reaches the inter-terminal voltage VB of the second storage battery 32. If the control device 100 determines that the inter-terminal voltage Vcinv of the capacitor 90 does not increase during the period from time t5 to t6, it determines that a close fault has not occurred in the connection switch 93, and if it determines that the inter-terminal voltage Vcinv will increase, it determines that a close fault has occurred in the connection switch 93.

[0156] At time t7, the control device 100 turns on the motor-side switch 60. That is, the first half of the pre-charging of the capacitor 90 is performed by supplying charge from the smoothing capacitor 21 by switching the inverter 20.

[0157] During the period from time t7 to t8, similar to the period from time t6 to t7 in FIG. 16, the control device 100 determines whether an open fault has occurred in the motor-side switch 60 based on the inter-terminal voltage Vcb of the capacitor 90.

[0158] At time t8, the control device 100 switches the low-side main switch SMRL to the ON position. At time t9, the control device 100 switches the pre-charge switch SP to the OFF position. This ends the startup sequence.

[0159] The control device 100 performs the processing shown in Fig. 2 during the period from time t9 to t10. During the period from time t9 to t10, the control device 100 determines whether an open fault has occurred in the low potential side main switch SMRL, similar to the period from time t8 to t9 in Fig. 16.

[0160] At time t10, the control device 100 switches the high potential side main switch SMRH to the OFF position to start the termination sequence.

[0161] At time t11, the control device 100 switches off the motor-side switch 60. The control device 100 transfers charge from the capacitor 90 to the smoothing capacitor 21 by performing switching control to repeatedly turn on and off at least one phase of the lower arm switch SWL, thereby completing the discharge of the capacitor 90.

[0162] At time t12, the control device 100 switches the connection switch 93 to the OFF position. The control device 100 controls the switching of the upper and lower arm switches SWH and SWL to release charge from the smoothing capacitor 21, completing the discharge of the smoothing capacitor 21. At time t13, the control device 100 switches the low potential side main switch SMRL and the inter-battery switch 40 to the OFF position. Thereafter, the termination sequence ends at time t14.

[0163] During the period from time t12 to t13, similar to the period from time t11 to t12 in FIG. 16, the control device 100 determines whether or not a closing failure has occurred in the high potential side main switch SMRH based on the inter-terminal voltage Vcinv of the smoothing capacitor 21.

[0164] <Modification of the third embodiment> As shown in FIG. 18, a series connection of a pre-charge switch SP and a resistor 95 may be connected in parallel to the motor-side switch 60.

[0165] For example, when the power conversion device is started up, the control device 100 performs a precharge process to charge the smoothing capacitor 21. In this embodiment, even if an abnormality occurs in either the first storage battery 31 or the second storage battery 32 and the battery becomes unusable, the precharge process can be performed using the remaining storage battery.

[0166] First, referring to Figure 19, a case where an abnormality occurs in the second storage battery 32 will be described. In this case, the control device 100 turns on the high potential side main switch SMRH, the pre-charge switch SP, and the inter-battery switch 40, and turns off the low potential side main switch SMRL, the motor side switch 60, and the inter-negative electrode bypass switch 50. The control device 100 also turns off the upper and lower arm switches SWH, SWL of all phases of the inverter 20. This allows the smoothing capacitor 21 to be charged by the first storage battery 31.

[0167] Next, a case where an abnormality occurs in the first storage battery 31 will be described with reference to Fig. 20. In this case, the control device 100 turns on the low potential side main switch SMRL and the pre-charge switch SP, and turns off the high potential side main switch SMRH, the motor side switch 60, the inter-battery switch 40, and the negative electrode bypass switch 50. The control device 100 also turns off the upper and lower arm switches SWH, SWL of all phases of the inverter 20. This allows the smoothing capacitor 21 to be charged by the second storage battery 32.

[0168] As shown in Fig. 21, a connection switch 93 and a capacitor 90 may be provided in the configuration shown in Fig. 20. In the pre-charge process for charging the smoothing capacitor 21, the control device 100 can simultaneously charge the smoothing capacitor 21 and the capacitor 90. In more detail, as shown in Fig. 22, the control device 100 turns on the high-side main switch SMRH, the pre-charge switch SP, and the inter-battery switch 40, and turns off the low-side main switch SMRL, the motor-side switch 60, and the inter-negative pole bypass switch 50. In addition, the control device 100 turns off the upper and lower arm switches SWH, SWL of all phases of the inverter 20.

[0169] <Fourth embodiment> The fourth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In this embodiment, as shown in Fig. 23, the power conversion device further includes an inter-positive electrode bypass switch 51 that connects the positive electrode terminal of the second storage battery 32 and the high potential side electrical path 22H.

[0170] For example, the control device 100 can charge the second storage battery 32 individually using the low-voltage charger 210 while turning on the positive electrode bypass switch 51 and turning off the negative electrode bypass switch 50, the battery switch 40, and the motor-side switch 60.

[0171] When performing the process shown in FIG. 2, the control device 100 only needs to turn off the positive electrode bypass switch 51.

[0172] Fifth Embodiment The fifth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In this embodiment, as shown in Fig. 24, the power conversion device includes a positive electrode-to-positive electrode bypass switch 51, and does not include the negative electrode-to-negative electrode bypass switch 50 shown in Fig. 1. In addition, the motor-side electrical path 25 connects the neutral point of the armature winding 11 to a portion of the inter-battery electrical path 24 that is closer to the first storage battery 31 than the inter-battery switch 40. A motor-side switch 61 is provided in the motor-side electrical path 25.

[0173] In this embodiment, the series neutral mode is a mode in which the inter-battery switch 40 and the motor-side switch 61 are turned on and the positive-pole bypass switch 51 is turned off (see FIG. 25). The motor-via-parallel mode is a mode in which the inter-battery switch 40 is turned off and the positive-pole bypass switch 51 and the motor-side switch 61 are turned on (see FIG. 26).

[0174] Next, the power transmission control process of this embodiment will be described with reference to Fig. 2. The following mainly describes the differences from the first embodiment.

[0175] In step S12, if it is determined that the value obtained by subtracting the second detected voltage VB from the first detected voltage VA is equal to or less than the determination threshold ΔVjde, it is determined that the transition to the motor-via-motor parallel mode is possible, and if it is determined that the value obtained by subtracting the second detected voltage VB from the first detected voltage VA is greater than the determination threshold ΔVjde, it is determined that the transition to the motor-via-motor parallel mode is not possible. If the terminal voltage of the first storage battery 31 is too high compared to the terminal voltage of the second storage battery 32, when the operation modes of the inter-battery switch 40, the positive pole bypass switch 51, and the motor-side switch 61 are switched to the motor-via-motor parallel mode, a closed circuit is formed from the first storage battery 31, including the high-potential side electrical path 22H, the positive pole bypass switch 51, the second storage battery 32, the low-potential side electrical path 22L, the lower-arm diode DL connected in anti-parallel to the lower-arm switch SWL, the armature winding 11, and the motor-side switch 61, causing a phenomenon in which current flows from the first storage battery 31 to the second storage battery 32.

[0176] When the process proceeds to step S19 via steps S17 and S18, a low-voltage charging mode is performed in which the second storage battery 32 is charged by the low-voltage charger 210 with the main switches SMRH and SMRL and the charging switches DCRH and DCRL turned on. In this mode, as shown in Fig. 26 , a current flows through a closed circuit including the low-voltage charger 210, the high-potential side electrical path 22H, the positive electrode bypass switch 51, the second storage battery 32, and the low-potential side electrical path 22L, and the second storage battery 32 is charged by the low-voltage charger 210.

[0177] Here, in the low-voltage charging mode, the charging power of the first storage battery 31 and the second storage battery 32 can be adjusted individually. This adjustment can be performed by repeatedly switching on and off the lower-arm switches SWL for at least one phase in the inverter 20 while the first storage battery 31 is being charged by the low-voltage charger 210. Here, the charging power of the first storage battery 31 and the second storage battery 32 can be adjusted by adjusting the duty ratio (Ton / Tsw), which is the ratio of the on-period Ton of the lower-arm switch SWL to one switching cycle Tsw.

[0178] Even in the low-voltage charging mode, the second storage battery 32 is charged by the low-voltage charger 210, and at least one phase of the inverter 20 is switched to perform voltage equalization, capacity equalization, and temperature rise control.

[0179] In step S27, the lower arm switch SWL of at least one phase is repeatedly switched on and off, provided that the upper and lower arm switches SWH, SWL of the same phase are not simultaneously turned on, thereby transmitting power from the second storage battery 32 to the first storage battery 31 until the difference between the first detection voltage VA and the second detection voltage VB becomes equal to or less than the potential threshold Vth. If it is determined that the difference between the first detection voltage VA and the second detection voltage VB has become equal to or less than the potential threshold, the process proceeds to step S18, where the operation mode is switched to the motor-via parallel mode, and the low-voltage charging mode is performed in step S19.

[0180] According to the present embodiment described above, it is possible to achieve the same effects as the first embodiment.

[0181] Sixth Embodiment The sixth embodiment will be described below with reference to the drawings, focusing on the differences from the fifth embodiment. In this embodiment, as shown in Fig. 27, the power conversion device further includes a positive-to-positive bypass switch 51 in addition to a negative-to-negative bypass switch 50.

[0182] For example, the control device 100 can individually charge the first storage battery 31 using the low-voltage charger 210 while turning on the negative electrode bypass switch 50 and turning off the positive electrode bypass switch 51, the battery switch 40, and the motor side switch 61.

[0183] When performing the process shown in FIG. 2, the control device 100 only needs to turn off the negative electrode bypass switch 50.

[0184] Seventh Embodiment The seventh embodiment will be described below with reference to the drawings, focusing on the differences from the above-mentioned embodiments. In this embodiment, as shown in Fig. 28, in addition to a switch connecting the neutral point of the armature winding 11 to the negative terminal of the first storage battery 31, a switch connecting the neutral point of the armature winding 11 to the positive terminal of the second storage battery 32 is provided as a motor-side switch.

[0185] A first end of a common path 26 is connected to the neutral point of the armature winding 11. A first end of a first electrical path 27 is connected to a second end of the common path 26, and a second end of the first electrical path 27 is connected to a part of the inter-battery electrical path 24 that is closer to the second storage battery 32 than the inter-battery switch 40. A first end of a second electrical path 28 is connected to the second end of the common path 26, and a second end of the second electrical path 28 is connected to a part of the inter-battery electrical path 24 that is closer to the first storage battery 31 than the inter-battery switch 40. A first motor-side switch 60 is provided in the first electrical path 27. A second motor-side switch 61 is provided in the second electrical path 28. It is also possible to omit the common path 26 and have the first ends of the first electrical path 27 and the second electrical path 28 connected to the neutral point of the armature winding 11.

[0186] According to the present embodiment described above, the processing of FIG. 2 can be performed in the circuit configuration shown in FIG. 1, or the processing of FIG. 2 can be performed in the circuit configuration shown in FIG.

[0187] <Other embodiments> The above-described embodiments may be modified as follows.

[0188] As shown in FIG. 29 , a third current sensor 78 may be provided in a portion of the high-potential-side electrical path 22H between the connection point with the first storage battery 31 and the high-potential-side charging switch DCRH. A fourth current sensor 79 may be provided at any position in the motor-side electrical path 25. For example, the fourth current sensor 79 may be provided in the motor-side electrical path 25 closer to the neutral point than the motor-side switch 60. It is sufficient to provide at least two of the first to fourth current sensors 73, 74, 78, and 79. This enables charging control of the storage batteries 31 and 32 using as few current sensors as possible. A current sensor may be provided to detect the current flowing through each conductive member 23, and the sum of the detected values of the currents flowing through the conductive members 23 may be used instead of the detected value of the fourth current sensor.

[0189] The connection destination of the motor-side electrical path 25 is not limited to the neutral point of the armature winding 11, but may be, for example, a middle portion of the armature winding 11 as shown in FIG.

[0190] 31, the connection destination of motor-side electrical path 25 may be conductive member 23. In this case, as shown in FIG. 32, the switching of inverter 20 in steps S15, S19, and S22 in FIG. 2 may be performed by turning off the upper and lower arm switches SWH, SWL of the phase in which motor-side electrical path 25 is connected to conductive member 23, and alternately turning on the upper and lower arm switches SWH, SWL of at least one phase other than the phase in which motor-side electrical path 25 is connected to conductive member 23.

[0191] As shown in FIG. 33, a high potential side charging switch DCRH and a positive electrode side connection part may be provided on the high potential side electrical path 22H on the side opposite the first storage battery 31 side relative to the inverter 20, and a low potential side charging switch DCRL and a negative electrode side connection part may be provided on the low potential side electrical path 22L on the side opposite the second storage battery 32 side relative to the inverter 20.

[0192] 34, the positive terminal of the first storage battery 31 and the high-potential-side electrical path 22H may be connected by a first fuse 110A. Also, the negative terminal of the second storage battery 32 and the low-potential-side electrical path 22L may be connected by a second fuse 110B.

[0193] When the control device 100 determines that there is a request for power transmission while the vehicle CA is traveling, the control device 100 may perform the voltage equalization process or capacity equalization process described above while switching the inverter 20 to control the control variable (torque) of the motor 10 to a target value. This process will be described using FIG. 35, assuming the circuit configuration shown in FIG. 1.

[0194] In step S30, it is determined whether the vehicle CA is moving.

[0195] If it is determined in step S30 that the vehicle is traveling, the process proceeds to step S31, where it is determined whether or not there is a power transmission request. Here, it is determined that there is a power transmission request if the above condition (c) is met.

[0196] If it is determined in step S31 that there is no request for power transmission, the process proceeds to step S32, where the inverter 20 is switched on and off to control the torque of the motor 10 to a target value and run the vehicle CA. Here, the motor-side switch 60 and the negative-electrode bypass switch 50 are turned off.

[0197] On the other hand, if it is determined in step S31 that there is a power transmission request, the process proceeds to step S33, where the inverter 20 is switched to control the torque of the motor 10 to a target value to run the vehicle CA. At the same time, the inverter 20 is also switched for the capacity equalization process described above. Here, the operation mode is set to the series neutral point mode.

[0198] This allows the vehicle CA to travel by controlling the drive of the motor 10 while preventing a large difference in the state of charge between the first and second storage batteries 31, 32. Therefore, it is possible to prevent the state of charge of one of the first and second storage batteries 31, 32 from reaching the allowable lower limit while maintaining the state of charge of the other storage battery 31, 32 at a value higher than its allowable lower limit, thereby extending the travel distance of the vehicle CA.

[0199] The main switches SMRH, SMRL, charging switches DCRH, DCRL, inter-battery switch 40, bypass switch, motor-side switch, and connection switch are not limited to being composed of a single switch, and may be composed of a series connection of multiple switches or a parallel connection of multiple switches.

[0200] The switches of the inverter 20 are not limited to IGBTs with freewheel diodes connected in antiparallel, but may also be, for example, N-channel MOSFETs with body diodes. In this case, the high-potential terminal of the N-channel MOSFET becomes the drain, and the low-potential terminal becomes the source.

[0201] The motor side electrical path does not need to have a motor side switch.

[0202] The motor is not limited to a star-connected one, but may be a delta-connected one. The motor and inverter are not limited to a three-phase one, but may be a two-phase one, or four or more phases. 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.

[0203] The power storage unit to be charged by the external charger is not limited to a storage battery, but may be, for example, a large-capacity electric double layer capacitor, or one that includes both a storage battery and an electric double layer capacitor.

[0204] 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.

[0205] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0206] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. a high-potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low-potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second power storage unit (32); an inverter (20) having an upper arm switch (SWH) electrically connected to the high potential side electrical path and a lower arm switch (SWL) electrically connected to the low potential side electrical path; a motor (10) having an armature winding (11) electrically connected to a connection point of the upper arm switch and the lower arm switch via a conductive member (23); In a power conversion device comprising: an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a bypass switch (50, 51) that electrically connects at least one of the negative electrode terminals of the first power storage unit and the second power storage unit and the positive electrode terminals of the first power storage unit and the second power storage unit; a motor-side electrical path (25-28) electrically connecting the armature winding or the conductive member to the electrical path between the power storage units; A control unit (100); Equipped with The control unit determining whether there is a request for power transmission between the first power storage unit and the second power storage unit; when it is determined that there is a power transmission request, the power conversion device controls power transmission between the first power storage unit and the second power storage unit by switching the inverter in a state in which the operation modes of the inter-power storage unit switch and the bypass switch are set to a first mode in which the inter-power storage unit switch is turned on and the bypass switch is turned off, or a second mode in which the inter-power storage unit switch is turned off and the bypass switch is turned on.

2. The control unit permitting execution of the second mode when it is determined that the difference between the voltage of the first power storage unit and the voltage of the second power storage unit is equal to or smaller than a determination threshold; The power conversion device according to claim 1 , wherein execution of the second mode is prohibited when it is determined that the difference between the voltage of the first power storage unit and the voltage of the second power storage unit exceeds the determination threshold value.

3. the bypass switch is an inter-negative electrode bypass switch (50) that electrically connects the negative electrode terminal of the first power storage unit and the negative electrode terminal of the second power storage unit, the motor-side electrical path (25) is a path that electrically connects the armature winding to a portion of the inter-energy-storage-unit electrical path that is closer to the second energy storage unit than the inter-energy-storage-unit switch, A positive terminal of an external charger (200, 210) can be electrically connected to the high-potential side electrical path, a negative terminal of the external charger can be electrically connected to the low-potential side electrical path, The external charger is a high-voltage charger (200) or a low-voltage charger (210) having a charging voltage lower than that of the high-voltage charger, The control unit determining that there is a power transmission request when there is a charging request by the low-voltage charger; 3. The power conversion device according to claim 2, wherein, when it is determined that there is a power transmission request and execution of the second mode is permitted, the power transmission control is performed while charging using the low-voltage charger in a state in which the operation mode is set to the second mode.

4. 4. The power conversion device according to claim 3, wherein, when the operation mode is set to the second mode, the control unit individually adjusts the charging power of the first storage unit and the charging power of the second storage unit by performing the power transmission control while charging using the low-voltage charger.

5. the bypass switch is an inter-negative electrode bypass switch (50) that electrically connects the negative electrode terminal of the first power storage unit and the negative electrode terminal of the second power storage unit, the motor-side electrical path (25) is a path that electrically connects the armature winding to a portion of the inter-energy-storage-unit electrical path that is closer to the second energy storage unit than the inter-energy-storage-unit switch, A positive terminal of an external charger (200, 210) can be electrically connected to the high-potential side electrical path, a negative terminal of the external charger can be electrically connected to the low-potential side electrical path, The external charger is a high-voltage charger (200) or a low-voltage charger (210) having a charging voltage lower than that of the high-voltage charger, The control unit determining that there is a power transmission request when there is a charging request by the low-voltage charger; The power conversion device according to claim 2 , wherein the operation mode is set to the first mode when it is determined that there is a power transmission request and execution of the second mode is prohibited.

6. The control unit When the operation mode is set to the first mode, by switching the upper arm switch of at least one phase on the condition that the upper and lower arm switches of the same phase are not turned on simultaneously, power is transmitted from the second power storage unit to the first power storage unit so that a difference in voltage between the first power storage unit and the second power storage unit becomes equal to or less than the determination threshold value; 6. The power conversion device according to claim 5, wherein when it is determined that the difference between the voltage of the first storage unit and the voltage of the second storage unit is equal to or less than the determination threshold, the operation mode is switched to the second mode, and the power transmission control is performed while charging using the low-voltage charger.

7. the bypass switch is an inter-positive electrode bypass switch (51) that electrically connects a positive electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit, the motor-side electrical path (25) is a path that electrically connects the armature winding to a portion of the inter-energy-storage-unit electrical path that is closer to the first energy storage unit than the inter-energy-storage-unit switch, A positive terminal of an external charger (200, 210) can be electrically connected to the high-potential side electrical path, a negative terminal of the external charger can be electrically connected to the low-potential side electrical path, The external charger is a high-voltage charger (200) or a low-voltage charger (210) having a charging voltage lower than that of the high-voltage charger, The control unit determining that there is a power transmission request when there is a charging request by the low-voltage charger; 3. The power conversion device according to claim 2, wherein, when it is determined that there is a power transmission request and execution of the second mode is permitted, the power transmission control is performed while charging using the low-voltage charger in a state in which the operation mode is set to the second mode.

8. 8. The power conversion device according to claim 7, wherein, when the operation mode is set to the second mode, the control unit individually adjusts the charging power of the first storage unit and the charging power of the second storage unit by performing the power transmission control while charging using the low-voltage charger.

9. the bypass switch is an inter-positive electrode bypass switch (51) that electrically connects a positive electrode terminal of the first power storage unit and a positive electrode terminal of the second power storage unit, the motor-side electrical path (25) is a path that electrically connects the armature winding to a portion of the inter-energy-storage-unit electrical path that is closer to the first energy storage unit than the inter-energy-storage-unit switch, A positive terminal of an external charger (200, 210) can be electrically connected to the high-potential side electrical path, a negative terminal of the external charger can be electrically connected to the low-potential side electrical path, The external charger is a high-voltage charger (200) or a low-voltage charger (210) having a charging voltage lower than that of the high-voltage charger, The control unit determining that there is a power transmission request when there is a charging request by the low-voltage charger; The power conversion device according to claim 2 , wherein the operation mode is set to the first mode when it is determined that there is a power transmission request and execution of the second mode is prohibited.

10. The control unit When the operation mode is set to the first mode, by switching the lower arm switch of at least one phase on the condition that the upper and lower arm switches of the same phase are not turned on simultaneously, power is transmitted from the first power storage unit to the second power storage unit so that a difference in voltage between the first power storage unit and the second power storage unit becomes equal to or less than the determination threshold value; 10. The power conversion device according to claim 9, wherein when it is determined that the difference between the voltage of the first storage unit and the voltage of the second storage unit is equal to or less than the determination threshold, the operation mode is switched to the second mode, and the power transmission control is performed while charging using the low-voltage charger.

11. charging switches (DCRH, DCRL) that are provided in the high potential side electrical path and the low potential side electrical path, that electrically connect the external charger to the first power storage unit and the second power storage unit when turned on, and that electrically disconnect the external charger from the first power storage unit and the second power storage unit when turned off; The power conversion device according to claim 5 , wherein the control unit sets the operation mode to the first mode when the charging switch is turned off.

12. A positive terminal of an external charger (200, 210) can be electrically connected to the high-potential side electrical path, a negative terminal of the external charger can be electrically connected to the low-potential side electrical path, The external charger is a high-voltage charger (200) or a low-voltage charger (210) having a charging voltage lower than that of the high-voltage charger, The control unit determining that there is a power transmission request when there is a charging request by the high-voltage charger; The control unit 3. The power conversion device according to claim 2, wherein, when it is determined that there is a power transmission request, the power transmission control is performed while the high-voltage charger charges at least one of the first storage unit and the second storage unit, with the operation mode set to the first mode.

13. 13. The power conversion device according to claim 12, wherein, when the operation mode is set to the first mode, the control unit performs the power transmission control while charging at least one of the first storage unit and the second storage unit using the high-voltage charger, thereby individually adjusting the charging power of the first storage unit and the charging power of the second storage unit.

14. A motor-side switch (60) is provided in the motor-side electrical path, The control unit calculating a total number of switching times of the inter-power-storage unit switch, the bypass switch, and the motor-side switch when transitioning from the current operation mode to the next operation mode via the power transmission control in which the first mode is selected; calculating a total number of switching times of the inter-power-storage unit switch, the bypass switch, and the motor-side switch when transitioning from the current operation mode to the next operation mode via the power transmission control in which the second mode is selected; 2. The power conversion device according to claim 1, wherein, when implementation of the second mode is permitted, one of the first mode and the second mode, whichever has a smaller total number of switching times, is selected in the power transmission control.

15. A motor-side switch (60) is provided in the motor-side electrical path, The control unit calculating a total number of switching operations of the inter-power storage unit switch, the bypass switch, and the motor-side switch when transitioning from the current operation mode to the power transmission control in which the first mode is selected; calculating a total number of switching operations of the inter-power storage unit switch, the bypass switch, and the motor-side switch when transitioning from the current operation mode to the power transmission control in which the second mode is selected; 2. The power conversion device according to claim 1, wherein, when implementation of the second mode is permitted, one of the first mode and the second mode, whichever has a smaller total number of switching times, is selected in the power transmission control.

16. a capacitance parameter is any one of a voltage of the first power storage unit and the second power storage unit, a charge rate of the first power storage unit and the second power storage unit, and a correlation value between the voltage or the charge rate of the first power storage unit and the second power storage unit; The control unit determining that there is a power transmission request when it is determined that a difference between the capacity parameter of the first power storage unit and the capacity parameter of the second power storage unit exceeds a threshold; 2. The power conversion device according to claim 1, wherein, when it is determined that there is a power transmission request, the power transmission control is performed in a state in which the operation mode is set to the first mode or the second mode, so that the difference between the capacity parameter of the first storage unit and the capacity parameter of the second storage unit is reduced.

17. The control unit determining that there is a power transmission request when it is determined that a temperature parameter, which is either the temperatures of the first power storage unit and the second power storage unit or a correlation value of the temperatures, is below a temperature threshold; 2. The power conversion device according to claim 1, wherein, when it is determined that there is a power transmission request, with the operation mode set to the first mode or the second mode, the power transmission control is performed such that a charging / discharging current flows between the first power storage unit and the second power storage unit via the armature winding and the inverter.

18. The power conversion device is mounted on a moving object (CA), the motor is a power source for moving the moving body, 2. The power conversion device according to claim 1, wherein, when it is determined that the power transmission request is present while the moving body is moving, the control unit performs the power transmission control while switching the inverter to move the moving body.

19. a high-potential side electrical path (22H) electrically connectable to a positive electrode terminal of the first storage unit (31); a low-potential side electrical path (22L) electrically connectable to a negative electrode terminal of the second power storage unit (32); an inverter (20) having an upper arm switch (SWH) electrically connected to the high potential side electrical path and a lower arm switch (SWL) electrically connected to the low potential side electrical path; a motor (10) having an armature winding (11) electrically connected to a connection point of the upper arm switch and the lower arm switch via a conductive member (23); A computer (101); A program applied to a power conversion device comprising: The power conversion device is an inter-storage unit switch (40) provided in an inter-storage unit electrical path (24) that electrically connects the negative electrode terminal of the first storage unit and the positive electrode terminal of the second storage unit; a bypass switch (50, 51) that electrically connects at least one of the negative electrode terminals of the first power storage unit and the second power storage unit and the positive electrode terminals of the first power storage unit and the second power storage unit; a motor-side electrical path (25-28) electrically connecting the armature winding or the conductive member to the electrical path between the power storage units; Equipped with The computer, a process of determining whether there is a request for power transmission between the first power storage unit and the second power storage unit; a process of controlling power transmission between the first power storage unit and the second power storage unit by switching the inverter, in a state where operation modes of the inter-power-storage unit switch and the bypass switch are set to a first mode in which the inter-power-storage unit switch is turned on and the bypass switch is turned off, or a second mode in which the inter-power-storage unit switch is turned off and the bypass switch is turned on; A program that executes.

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