Power conversion device, program

Abstract

The power conversion device comprises: an inter-power-storage-unit switch (40) that is provided in an inter-power-storage-unit electrical path (24) that electrically connects a negative terminal of a first power storage unit (31) and a positive terminal of a second power storage unit (32); a bypass switch (50, 51) that makes an electrical connection between the negative terminals of the first and second power storage units and / or an electrical connection between the positive terminals of the first and second power storage units; motor-side electrical paths (25 to 28) that electrically connect armature windings (11) or conductive members (23) to the inter-power-storage-unit electrical path; and a control unit (100). The control unit starts charging at least one of the first and second power storage units by an external charger (210) in a state in which the inter-power-storage-unit switch is turned off and the bypass switch is turned on, and, after starting the charging by the external charger, carries out switching processing of an inverter (20) to make a voltage difference between the first and second power storage units no greater than a determination threshold.

Description

Cross - reference to related applications

[0001] This application is based on Japanese Application No. 2022 - 144019 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 Art

[0003] Conventionally, as described in Patent Document 1, a power supply device capable of switching the connection state of a first battery and a second battery between a series connection state and a parallel connection state is known. This power supply device includes a relay for switching the connection state of the first battery and the second battery to the series connection state or the parallel connection state with respect to an external charger.

[0004] When the voltage difference between the first battery and the second battery is equal to or greater than a threshold value, the power supply device operates the relay so that only the battery with the lower voltage among the first battery and the second battery can be charged by the external charger. Thereby, the voltages of the first battery and the second battery are equalized.

[0005] On the other hand, when the voltage difference between the first battery and the second battery becomes less than the threshold value, the power supply device operates the relay to switch the connection state of the first battery and the second battery to the parallel connection state so that both the first battery and the second battery can be charged by the external charger. Thereby, it is possible to prevent the connection state from being switched to the parallel connection state when the voltage difference between the first battery and the second battery is large, and thus prevent an inrush current from flowing through each battery due to this switching.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] There is a demand for a new power conversion device capable of switching the connection state of a first power storage unit such as a first battery and a second power storage unit such as a second battery to an external charger.

[0008] The main object of the present disclosure is to provide a power conversion device and a program capable of switching the connection state of a first power storage unit and a second power storage unit to an external charger.

[0009] The present disclosure includes a high-potential-side electrical path electrically connectable to the positive terminal of the first power storage unit and the positive terminal of the external charger, a low-potential-side electrical path electrically connectable to the negative terminal of the second power storage unit and the negative terminal of the external charger, 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 the connection point of the upper-arm switch and the lower-arm switch via a conductive member, In a power conversion device including: an inter-storage-unit switch provided in an inter-storage-unit electrical path that electrically connects the negative terminal of the first power storage unit and the positive terminal of the second power storage unit; a bypass switch that makes at least one of the electrical connection between the negative terminals of the first power storage unit and the second power storage unit and the electrical connection between the positive terminals of the first power storage unit and the second power storage unit; a motor-side electrical path that electrically connects the armature winding or the conductive member and the inter-storage-unit electrical path; a control unit; including: The control unit: With the inter-storage-unit switch turned off and the bypass switch turned on, charging of at least one of the first power storage unit and the second power storage unit by the external charger is started. After the start of charging by the external charger, a voltage adjustment process is performed, which is a switching process of the inverter to make the voltage difference between the first power storage unit and the second power storage unit equal to or less than a determination threshold value.

[0010] In the present disclosure, when the inter-storage unit switch is turned on and the bypass switch is turned off, the first power storage unit and the second power storage unit are connected in series to the external charger. On the other hand, when the inter-storage unit switch is turned off and the bypass switch is turned on, either the first power storage unit or the second power storage unit is connected in parallel to the external charger. Thus, according to the present disclosure, the connection state of the first power storage unit and the second power storage unit to the external charger can be switched.

[0011] The control unit of the present disclosure starts charging at least one of the first power storage unit and the second power storage unit with the external charger in a state where the inter-storage unit switch is turned off and the bypass switch is turned on. After the start of charging by the external charger, the control unit performs a voltage adjustment process, which is a switching process of the inverter to make the voltage difference between the first power storage unit and the second power storage unit equal to or less than a determination threshold value. In the voltage adjustment process, power is transmitted between the first power storage unit and the second power storage unit via the inverter and the armature winding, and the voltage difference is made equal to or less than the determination threshold value. Thereby, it is possible to suppress a large current from flowing from one of the first power storage unit and the second power storage unit to the other via the inverter and the armature winding due to a large voltage difference between the first power storage unit and the second power storage unit.

[0012] Also, the configuration of the motor and the inverter is reused to make the voltage difference between the first power storage unit and the second power storage unit equal to or less than a determination threshold value. Therefore, a power conversion device with a simplified configuration can be provided.

Brief Description of the Drawings

[0013] The above objects, other objects, features, and advantages of the present disclosure will become clearer from the following detailed description with reference to the accompanying drawings. The drawings are

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Embodiments for Carrying Out the Invention

[0014] A plurality of embodiments will be described with reference to the drawings. In a plurality of embodiments, parts that are functionally and / or structurally corresponding and / or associated may be assigned the same reference numerals, or reference numerals that differ in the hundreds place or more. For corresponding parts and / or associated parts, reference may be made to the description of other embodiments.

[0015] <First Embodiment> Hereinafter, a first embodiment in which a power conversion device according to the present disclosure is embodied will be described with reference to the drawings. The power conversion device of this embodiment is mounted on a vehicle such as an electric vehicle or a hybrid vehicle and constitutes an in-vehicle system.

[0016] 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 stator windings 11 of U, V, and W phases connected in a star configuration and a rotor (not shown). The stator windings 11 of each phase are arranged with a 120° electrical angle shift. The motor 10 is, for example, a permanent magnet synchronous machine. The rotor is capable of power transmission to the drive wheels of the vehicle CA. Therefore, the motor 10 is a torque generation source for driving the vehicle CA.

[0017] The inverter 20 includes three sets of series-connected bodies of upper-arm switches SWH and lower-arm switches SWL. An upper-arm diode DH, which is a freewheel diode, is connected in antiparallel to the upper-arm switch SWH, and a lower-arm diode DL, which is a freewheel diode, is connected in antiparallel to the lower-arm switch SWL. In this embodiment, each switch SWH, SWL is an IGBT.

[0018] The inverter 20 includes a smoothing capacitor 21. The first end side of a long high-potential-side electrical path 22H is connected to the high-potential-side terminal of the smoothing capacitor 21. The first end side of a long low-potential-side electrical path 22L is connected to the low-potential-side terminal of the smoothing capacitor 21. Note that the smoothing capacitor 21 may be provided outside the inverter 20.

[0019] In each phase, the first end of the armature winding 11 is connected to the connection point between the emitter, which is the low-potential-side terminal of the upper-arm switch SWH, and the collector, which is the high-potential-side terminal of the lower-arm switch SWL, via a conductive member 23 such as a bus bar. The second ends of the armature windings 11 of each phase are connected at the neutral point. Note that in the present embodiment, the number of turns of the armature winding 11 of each phase is set to be the same. Thereby, the inductance of the armature winding 11 of each phase is set to be the same, for example.

[0020] The high-potential-side electrical path 22H is connected to the collector of the upper-arm switch SWH of each phase. The low-potential-side electrical path 22L is connected to the emitter of the lower-arm switch SWL of each phase.

[0021] 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 and 32 serves as a power supply source for rotationally driving the rotor of the motor 10. Each of the storage batteries 31 and 32 is a battery pack configured as a series connection body of battery cells that are single cells. The positive terminal of the first storage battery 31 is connected to the second end side of the high-potential-side electrical path 22H, which is opposite to the connection point side of the smoothing capacitor 21, and the negative terminal of the second storage battery 32 is connected to the second end side of the low-potential-side electrical path 22L, which is opposite to the connection point side of the smoothing capacitor 21. The terminal voltages (for example, rated voltages) of the battery cells constituting the battery pack are set to be the same as each other, for example. The battery cell is a secondary battery such as a lithium-ion battery, for example.

[0022] Each of the storage batteries 31 and 32 in this embodiment is a storage battery with the same rated voltage and full charge capacity. Each of the storage batteries 31 and 32 can be charged by an external charger, which will be described later, provided outside the vehicle CA. The external charger is, for example, a stationary charger. A positive electrode side connection part to which the positive electrode terminal of the external charger can be connected is provided at the first end side of the high potential side electrical path 22H. A negative electrode side connection part to which the negative electrode terminal of the external charger can be connected is provided at the first end side of the low potential side electrical path 22L.

[0023] The power conversion device includes main switches for electrically connecting or disconnecting between the first and second storage batteries 31 and 32 and the inverter 20. Specifically, a high potential side main switch SMRH and a low potential side main switch SMRL are provided as the main switches. The power conversion device also includes charge switches for electrically connecting or disconnecting between the external charger and the inverter 20. Specifically, a high potential side charge switch DCRH and a low potential side charge switch DCRL are provided as the charge switches. In this embodiment, each of the switches SMRH, SMRL, DCRH, and DCRL is a mechanical relay. When each of the switches SMRH, SMRL, DCRH, and DCRL is turned off, it blocks the flow of bidirectional current, and when it is turned on, it allows the flow of bidirectional current. The high potential side electrical path 22H is provided with the high potential side main switch SMRH and the high potential side charge switch DCRH in order from the first storage battery 31 side. The low potential side electrical path 22L is provided with the low potential side main switch SMRL and the low potential side charge switch DCRL in order from the second storage battery 32 side. Note that the high potential side main switch SMRH, the low potential side main switch SMRL, the high potential side charge switch DCRH, and the low potential side charge switch DCRL are not limited to mechanical relays and may be, for example, semiconductor switching elements.

[0024] The power conversion device includes a battery - to - battery switch 40, a negative - to - negative bypass switch 50, and a motor - side switch 60 as switches for switching the connection modes of the first battery 31 and the second battery 32 to an external charger. In this embodiment, the battery - to - battery switch 40, the negative - to - negative bypass switch 50, and the motor - side switch 60 are mechanical relays. When the battery - to - battery switch 40, the negative - to - negative bypass switch 50, and the motor - side switch 60 are turned off, they block the flow of bidirectional current, and when they are turned on, they allow the flow of bidirectional current. Note that the battery - to - battery switch 40, the negative - to - negative bypass switch 50, and the motor - side switch 60 are not limited to mechanical relays and may be, for example, semiconductor switching elements.

[0025] The battery - to - battery switch 40 is provided in an inter - battery electrical path 24 (corresponding to the "inter - energy - storage - unit electrical path") that connects the negative - terminal of the first battery 31 and the positive - terminal of the second battery 32. When the battery - to - battery switch 40 is turned on, the negative - terminal of the first battery 31 and the positive - terminal of the second battery 32 are electrically connected. On the other hand, when the battery - to - battery switch 40 is turned off, the negative - terminal of the first battery 31 and the positive - terminal of the second battery 32 are electrically disconnected.

[0026] The negative - to - negative bypass switch 50 connects the negative - terminal of the first battery 31 and the low - potential - side electrical path 22L. When the negative - to - negative bypass switch 50 is turned on, the negative - terminal of the first battery 31 and the negative - terminal of the second battery 32 are electrically connected. On the other hand, when the negative - to - negative bypass switch 50 is turned off, the negative - terminal of the first battery 31 and the negative - terminal of the second battery 32 are electrically disconnected.

[0027] The motor - side switch 60 is provided in a motor - side electrical path 25 that connects the side of the inter - battery electrical path 24 closer to the second battery 32 than the battery - to - battery switch 40 and 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 and the positive - terminal of the second battery 32 are electrically connected. On the other hand, when the motor - side switch 60 is turned off, the neutral point of the armature winding 11 and the positive - terminal of the second battery 32 are electrically disconnected.

[0028] The power conversion device includes a first voltage sensor 71 that detects the voltage across the terminals of the first storage battery 31, and a second voltage sensor 72 that detects the voltage across the terminals of the second storage battery 32. The power conversion device 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 in an electrical path that connects the positive terminal of the first storage battery 31 and the high-potential side electrical path 22H. The second current sensor 74 is provided in an electrical path that connects the negative terminal of the second storage battery 32 and the low-potential side electrical path 22L. Note that the power conversion device further includes, as other sensors, a rotation angle sensor that detects the rotation angle (electrical angle) of the rotor, and a phase current sensor that detects the phase current flowing through each phase of the armature winding 11.

[0029] The detection values of the respective sensors are input to a control device 100 (corresponding to a "control unit") provided in the power conversion device. The control device 100 is mainly constituted by a microcomputer 101, and the microcomputer 101 includes a CPU. The functions provided by the microcomputer 101 can be provided by software recorded in a physical memory device and a computer that executes the software, software only, hardware only, or a combination thereof. For example, when the microcomputer 101 is provided by an electronic circuit that is hardware, it can be provided by a digital circuit including a number of logic circuits or an analog circuit. For example, the microcomputer 101 executes a program stored in a non-transitory tangible storage medium as a storage unit provided therein. The program includes, for example, the program of the processing shown in FIG. 6 and the like described later. When the program is executed, the method corresponding to the program is executed. The storage unit is, for example, a non-volatile memory. Note that the program stored in the storage unit can be updated via a communication network such as the Internet, for example, OTA (Over The Air).

[0030] Based on the detection values of each sensor, the control device 100 performs switching control of each switch SWH and SWL that make up the inverter 20 to feedback-control the control amount of the motor 10 to a target value. The control amount is, for example, torque. In each phase, the upper arm switch SWH and the lower arm switch SWL are alternately turned on. Through this feedback control, the rotational power of the rotor is transmitted to the drive wheels of the vehicle CA, and the vehicle CA travels.

[0031] The positive electrode side connection part of the high potential side electric path 22H and the negative electrode side connection part of the low potential side electric path 22L are interfaces for connecting to an external charger. In the present embodiment, the external charger is a high voltage charger 200 or a low voltage charger 210 (see FIGS. 2 to 5). The charging voltage of the high voltage charger 200 is a voltage approximately the same as the voltage between the terminals of the series connection of the first and second storage batteries 31 and 32 (specifically, the rated voltage), for example, 800V. The charging voltage of the low voltage charger 210 is a voltage lower than the rated voltage of the series connection of the first and second storage batteries 31 and 32, for example, 400V. For example, when an external charger is connected to each connection part by a user or an operator and the first and second storage batteries 31 and 32 are charged by the external charger, the high potential side charging switch DCRH and the low potential side charging switch DCRL are switched on by the control device 100.

[0032] On the other hand, when charging by the external charger is not carried out or when the external charger is not connected, the high potential side charging switch DCRH and the low potential side charging switch DCRL are switched off by the control device 100. When the positive electrode side connection part and the negative electrode side connection part are exposed to the outside from the housing of the power conversion device, there is a possibility that they may be touched by a user or an operator. By turning off the high potential side charging switch DCRH and the low potential side charging switch DCRL, the occurrence of electric shock is prevented.

[0033] The control device 100 selects and executes either a high voltage charging mode in which the storage battery is charged by the high voltage charger 200 or a low voltage charging mode in which the storage battery is charged by the low voltage charger 210.

[0034] First, the high-voltage charging mode will be described with reference to FIG. 2.

[0035] When the control device 100 determines that the external charger connected to each connection part is the high-voltage charger 200, the control device 100 executes the high-voltage charging mode. In the high-voltage charging mode, the control device 100 turns on the inter-battery switch 40 and each main switch SMRH, SMRL so that the first battery 31 and the second battery 32 are connected in series to the high-voltage charger 200, and turns off the negative electrode bypass switch 50, the motor-side switch 60, and the upper and lower arm switches SWH, SWL of the inverter 20. As a result, as shown in FIG. 2, a current flows through a closed circuit including the high-voltage charger 200, the high-potential-side electrical path 22H, the first battery 31, the inter-battery switch 40, the second battery 32, and the low-potential-side electrical path 22L, and the first battery 31 and the second battery 32 are charged in a series-connected state. At this time, since the upper arm switch SWH of the inverter 20 and the motor-side switch 60 are turned off, it is possible to avoid the charging current of the high-voltage charger 200 from flowing through the inverter 20 and the armature winding 11.

[0036] Subsequently, the low-voltage charging mode will be described with reference to FIGS. 3 to 5.

[0037] When the control device 100 determines that the external charger connected to each connection part is the low-voltage charger 210, the control device 100 executes the low-voltage charging mode. The low-voltage charging mode includes Mode 1 shown in FIG. 3, Mode 2 shown in FIG. 4, and Mode 3 shown in FIG. 5.

[0038] First, Mode 1 will be described with reference to FIG. 3. In Mode 1, the control device 100 turns off the inter-battery switch 40, the motor-side switch 60, and the upper and lower arm switches SWH, SWL of the inverter 20, and turns on the negative electrode bypass switch 50 and each main switch SMRH, SMRL. As a result, as shown in FIG. 3, only the first battery 31 out of the first and second batteries 31 and 32 is charged by the low-voltage charger 210. In Mode 1, the second battery 32 is not charged.

[0039] Next, Mode 2 will be described with reference to FIG. 4. In Mode 2, the control device 100 turns off the inter-battery switch 40, the high-potential side main switch SMRH, and the lower arm switch SWL of the inverter 20, and turns on at least one upper arm switch SWH of the negative electrode bypass switch 50, the motor side switch 60, the low-potential side main switch SMRL, and the inverter 20. As a result, as shown in FIG. 4, only the second storage battery 32 out of the first and second storage batteries 31 and 32 is charged by the low-voltage charger 210. At this time, the charging current from the low-voltage charger 210 flows through the upper arm switch SWH, the conductive member 23, the armature winding 11, and the motor side electrical path 25. In Mode 2, the first storage battery 31 is not charged.

[0040] Next, Mode 3 will be described with reference to FIG. 5. In Mode 3, the control device 100 turns off the inter-battery switch 40 and turns on the negative electrode bypass switch 50, the motor side switch 60, and the main switches SMRH and SMRL. In Mode 3, based on the detection values of the first and second current sensors 73 and 74 and the first and second voltage sensors 71 and 72, 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 alternately turning on the upper and lower arm switches SWH and SWL for at least one phase of the inverter 20 while outputting a charging current from the low-voltage charger 210, or by repeating the on / off of the upper arm switch SWH for at least one phase while turning off the lower arm switch SWL. Here, by adjusting the duty ratio (Ton / Tsw), which is the ratio of the on-time Ton of the upper arm switch SWH to one switching period Tsw, the charging power of the first storage battery 31 and the second storage battery 32 can be adjusted individually. According to Mode 3, both the first and second storage batteries 31 and 32 can be charged.

[0041] Here, when charging the battery in the low-voltage charging mode with the motor-side switch 60 turned on, if the terminal voltage of the second battery 32 is too high relative to the terminal voltage of the first battery 31, a phenomenon occurs where a large current flows from the second battery 32 to the first battery 31 through the motor-side electrical path 25, the armature winding 11, the upper-arm diode DH connected in antiparallel to the upper-arm switch SWH, and the high-potential-side electrical path 22H. In this case, the reliability of the power conversion device and each of the batteries 31, 32 may decrease.

[0042] Therefore, in order to suppress the occurrence of the phenomenon where current flows from the second battery 32 to the first battery 31 via the motor 10 and the inverter 20, or to reduce the amount of current flowing even if this phenomenon occurs, the control device 100 performs the charging process shown in FIG. 6 in the low-voltage charging mode. This process is repeatedly executed by the control device 100, for example, at a predetermined control cycle. Note that the process shown in FIG. 6 is assumed to be executed, for example, while the vehicle CA is stopped (a specific example is when parked).

[0043] In step S10, it is determined that the current timing is the charging start timing of the charging control period, and charging in the low-voltage charging mode is started.

[0044] In step S11, it is determined whether or not the absolute value of the difference between the terminal voltage of the first battery 31 (hereinafter, the first detected voltage VA) detected by the first voltage sensor 71 and the terminal voltage of the second battery 32 (hereinafter, the second detected voltage VB) detected by the second voltage sensor 72 is equal to or less than the determination threshold value ΔVjde. The process of step S11 is a process for determining whether or not it is a situation where the current flowing from the second battery 32 to the first battery 31 via the motor 10 and the inverter 20 becomes large.

[0045] Incidentally, the determination threshold value ΔVjde may be set, for example, to a voltage difference between the first battery 31 and the second battery 32 such that the maximum value and the steady value of the inrush current determined from the relationship between "the impedance of the current path existing between the first battery 31 and the second battery 32 (specifically, for example, the impedance of the first and second batteries 31, 32, the impedance of the inverter 20 and the armature winding 11, and the impedance in the forward direction of the diode of the inverter 20)" and "the voltage difference between the first battery 31 and the second battery 32" are equal to or less than the allowable value. Here, the allowable value is, for example, the maximum current that the components on the current path can withstand for safety reasons.

[0046] Further, the determination threshold value ΔVjde is a value smaller than the rated voltage of each of the batteries 31, 32. The determination threshold value ΔVjde is set, for example, to a value of 1 / 10 or less, 1 / 20 or less, 1 / 50 or less, or 1 / 100 or less of the lower value of the rated voltages of the respective batteries 31, 32.

[0047] If an affirmative determination is made in step S11, the process proceeds to step S12, and mode 3 shown in FIG. 5 is executed so as to maintain "VA ≥ VB" and "|VA - VB| ≤ ΔVjde". The process of step S12 corresponds to the voltage adjustment process.

[0048] In the subsequent step S13, it is determined whether the current timing is a specific timing. The specific timing is, for example, the timings of (A) to (E) below.

[0049] (A) The timing when the power Wоut charged to the first battery 31 among the output charging powers of the low-voltage charger 210 becomes larger than the allowable charging power Win of the first battery 31.

[0050] The allowable charging power is the maximum value of the charging power at which the reliability of the storage battery does not deteriorate. When the charging of the first storage battery 31 progresses and the SOC increases, the allowable charging power of the first storage battery 31 decreases. For this reason, as the charging progresses, there comes a timing when the charging power Wout of the first storage battery 31 among the output charging powers of the low-voltage charger 210 becomes larger than the allowable charging power Win of the first storage battery 31. By shifting to step S17 described later at this timing, the surplus output power of the low-voltage charger 210 with respect to the first storage battery 31 can be effectively utilized for charging the second storage battery 32.

[0051] (B) The timing at which the charging mode by the low-voltage charger 210 switches from the constant current mode CC in which the output current from the low-voltage charger 210 is a constant value to the constant voltage mode CV in which the output voltage of the low-voltage charger 210 is a constant value.

[0052] The charging power of the storage battery is larger in the constant current mode than in the constant voltage mode. For this reason, when switching to the constant voltage mode, surplus output power of the low-voltage charger 210 with respect to the first storage battery 31 may be generated. In this case, this surplus power can be effectively utilized for charging the second storage battery 32. Note that it may be determined that the switching is made to the constant voltage mode when it is determined that the first detection voltage VA has become equal to or higher than a predetermined voltage.

[0053] (C) The timing at which the charging mode by the low-voltage charger 210 switches from the constant current mode CC to the constant power mode CP in which the output power of the low-voltage charger 210 is a constant value.

[0054] The charging power of the storage battery is larger in the constant current mode than in the constant power mode. For this reason, when switching to the constant power mode, surplus output power of the low-voltage charger 210 with respect to the first storage battery 31 may be generated. In this case, this surplus power can be effectively utilized for charging the second storage battery 32.

[0055] (D) The timing at a predetermined period before the charging end timing in the charging control period.

[0056] The timing of (D) is used, for example, when the charging control period is set to a predetermined fixed period (e.g., 20 minutes). For example, when the predetermined period is set to 5 minutes, the specific timing is the timing when 15 minutes have elapsed from the start timing of charging. According to the timing of (D), for example, even when the charging process ends without fully charging the first and second storage batteries 31 and 32, the remaining capacity, charging rate, or terminal voltage of the first and second storage batteries 31 and 32 can be equalized. Here, the remaining capacity refers to the battery capacity taking into account the capacity of a new battery, the degree of deterioration, and the charging rate, and is represented, for example, by the following formula. In the following formula, SOH indicates the degree of deterioration of the storage battery.

[0057] Remaining capacity [Ah] = Full charge capacity [Ah] × Charge rate SOC [%] = (Capacity at the time of new product [Ah] × SOH [%]) × SOC [%] (E) The timing at which the charging rate (SOC) of the first storage battery 31 becomes a value obtained by subtracting a predetermined charging rate from the target charging rates of the first and second storage batteries 31 and 32 (e.g., 80%) at the end-of-charging timing. Note that, for example, the charging rate of the first storage battery 31 may be calculated based on the detection values of the first voltage sensor 71 and the first current sensor 73.

[0058] If it is determined in step S13 that the current timing is not the specific timing, the process proceeds to step S11. On the other hand, if it is determined that the current timing is the specific timing, the process proceeds to step S17.

[0059] In step S17, a voltage adjustment process is performed during a period after a specific timing within the charging control period. Specifically, while maintaining "VA ≥ VB" and "|VA - VB| ≤ ΔVjde", mode 3 is executed so that the difference between the first and second detected voltages VA and VB at the charging end timing of the charging control period becomes smaller than the difference between the first and second detected voltages VA and VB at the specific timing. Also, mode 3 is executed so that the charging current IB of the second battery 32 is made larger than the charging current IA of the first battery 31. According to the process of step S17, for example, the difference between the first and second detected voltages VA and VB gradually becomes smaller. Thereby, the remaining capacities, charging rates, or terminal voltages of the first and second batteries 31 and 32 can be equalized.

[0060] In step S18, it is determined whether the current timing has reached the charging end timing. The process of step S17 is continued until an affirmative determination is made in step S18.

[0061] By the way, at the charging start timing, the terminal voltage of the first battery 31 and the terminal voltage of the second battery 32 may be significantly different. In this case, a negative determination is made in step S11, and prior to the execution of the voltage adjustment process in step S11, a pre-charging process is performed in steps S14 to S16 to reduce the difference between the first and second detected voltages VA and VB. Specifically, first, in step S14, it is determined whether the second detected voltage VB is higher than the first detected voltage VA.

[0062] If it is determined in step S14 that the second detection voltage VB is higher than the first detection voltage VA, the process proceeds to step S15. In other words, if it is determined that the first detection voltage VA is lower than the value obtained by subtracting the determination threshold ΔVjde from the second detection voltage VB, the process proceeds to step S15. In step S15, mode 1 is executed in which only the first storage battery 31 out of the first and second storage batteries 31 and 32 is charged by the low-voltage charger 210 so that the absolute value of the difference between the first and second detection voltages VA and VB becomes equal to or less than the determination threshold ΔVjde (see FIG. 3). Then, the process proceeds to step S13. Note that in step S15, mode 1 may be further executed so that “VA≧VB”. Thereby, while quickly eliminating a state in which the charging rates of the first and second storage batteries 31 and 32 are greatly different, it is possible to accurately suppress current from flowing from the second storage battery 32 to the first storage battery 31 via the armature winding 11 and the inverter 20.

[0063] On the other hand, if it is determined in step S14 that the second detection voltage VB is lower than the first detection voltage VA, the process proceeds to step S16. In step S16, mode 2 is executed in which only the second storage battery 32 out of the first and second storage batteries 31 and 32 is charged by the low-voltage charger 210 so that the absolute value of the difference between the first and second detection voltages VA and VB becomes equal to or less than the determination threshold ΔVjde (see FIG. 4). Then, the process proceeds to step S13. Thereby, a state in which the charging rates of the first and second storage batteries 31 and 32 are greatly different can be quickly eliminated. Note that in step S16, mode 2 may be further executed so that “VA≧VB”.

[0064] Note that in step S16, mode 3 may be executed instead of mode 2. Specifically, mode 3 may be executed so that the charging current of the second storage battery 32 becomes larger than that of the first storage battery 31 and the absolute value of the difference between the first and second detection voltages VA and VB becomes equal to or less than the determination threshold ΔVjde. Thereby, while reducing the difference between the first and second detection voltages VA and VB, the charging period of the first and second storage batteries 31 and 32 can be shortened.

[0065] Next, an example of the charging process will be described with reference to FIGS. 7 to 9.

[0066] First, the example in FIG. 7 will be described.

[0067] The control device 100 starts the charging process at time t1. Here, at the start of charging, the control device 100 determines that the absolute value of the difference between the first and second detected voltages VA and VB exceeds the determination threshold value ΔVjde. Also, the control device 100 determines that the first detected voltage VA is lower than the second detected voltage VB. Therefore, the control device 100 executes Mode 1 in step S15. As a result, the first storage battery 31 is charged, and the first detected voltage VA starts to rise. On the other hand, since the second storage battery 32 is not charged, the second detected voltage VB remains constant.

[0068] At time t2, the control device 100 determines that the absolute value of the difference between the first and second detected voltages VA and VB has become equal to or less than the determination threshold value ΔVjde. Therefore, the control device 100 executes Mode 3 in step S12.

[0069] At time t3, the control device 100 determines that a specific timing has been reached. Therefore, the control device 100 executes Mode 3 in step S17 until time t4, which is the charging end timing of the charging control period. Since the charging current IB of the second storage battery 32 is larger than the charging current IA of the first storage battery 31, the rising speed of the second detected voltage VB is higher than the rising speed of the first detected voltage VA. As time approaches t4, the difference between the first and second detected voltages VA and VB becomes smaller. The difference between the first and second detected voltages VA and VB at time t4 is smaller than the difference between the first and second detected voltages VA and VB at time t3, and is, for example, smaller than the determination threshold value ΔVjde.

[0070] Subsequently, the example in FIG. 8 will be described.

[0071] The control device 100 starts the charging process at time t1. Here, at the start of charging, the control device 100 determines that the absolute value of the difference between the first and second detected voltages VA and VB exceeds the determination threshold value ΔVjde. Also, the control device 100 determines that the second detected voltage VB is lower than the first detected voltage VA. Therefore, the control device 100 executes Mode 2 of step S16. As a result, the second storage battery 32 is charged, and the second detected voltage VB starts to rise.

[0072] At time t2, the control device 100 determines that the absolute value of the difference between the first and second detected voltages VA and VB has become equal to or less than the determination threshold value ΔVjde. Therefore, the control device 100 executes Mode 3 of step S12.

[0073] At time t3, the control device 100 determines that a specific timing has been reached. Therefore, the control device 100 executes Mode 3 of step S17 until time t4, which is the charging end timing of the charging control period.

[0074] Subsequently, the example of FIG. 9 will be described. FIG. 9 is an example in the case where, in step S16, instead of Mode 2, Mode 3 is executed such that the charging current of the second storage battery 32 becomes larger than that of the first storage battery 31 and the absolute value of the difference between the first and second detected voltages VA and VB becomes equal to or less than the determination threshold value ΔVjde.

[0075] The control device 100 starts the charging process at time t1. Here, at the start of charging, the control device 100 determines that the absolute value of the difference between the first and second detected voltages VA and VB exceeds the determination threshold value ΔVjde. Also, the control device 100 determines that the second detected voltage VB is lower than the first detected voltage VA. Therefore, the control device 100 executes Mode 3 of step S16. As a result, the first and second storage batteries 31 and 32 are charged, and the first and second detected voltages VA and VB start to rise. At this time, since the charging current of the second storage battery 32 is larger than that of the first storage battery 31, the rising speed of the second detected voltage VB is higher than that of the first detected voltage VA.

[0076] At time t2, the control device 100 determines that the absolute value of the difference between the first and second detection voltages VA and VB is equal to or less than the determination threshold value ΔVjde. Therefore, the control device 100 executes Mode 3 in step S12.

[0077] At time t3, the control device 100 determines that a specific timing has been reached. Therefore, the control device 100 executes Mode 3 in step S17 until time t4, which is the charging end timing during the charging control period.

[0078] According to the present embodiment described above, it is possible to suppress the occurrence of a 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 flowing even if this phenomenon occurs.

[0079] In addition, the configurations of the motor 10 and the inverter 20 are reused to make the absolute value of the difference between the first and second detection voltages VA and VB equal to or less than the determination threshold value ΔVjde. As a result, in order to suppress the occurrence of a 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 flowing even if this phenomenon occurs, it is not necessary for the power conversion device to be equipped with additional electrical equipment (for example, a DC / DC converter). Therefore, it is possible to provide a power conversion device with a simplified configuration.

[0080] <Modification Example of the First Embodiment> In steps S12, S15 to S17 of FIG. 6, if the relationship of "|VA - VB| ≦ ΔVjde" is maintained, "VA < VB" may be satisfied.

[0081] <Second Embodiment> Hereinafter, the second embodiment will be described with reference to the drawings, centering on the differences from the first embodiment. In this embodiment, as shown in FIG. 10, the power conversion device includes a positive electrode bypass switch 51 and does not include the negative electrode bypass switch 50 shown in FIG. 1 above. Further, the motor-side electrical path 25 connects the neutral point of the armature winding 11 and a portion of the battery-to-battery electrical path 24 on the side of the first storage battery 31 closer to the battery-to-battery switch 40. A motor-side switch 61 is provided in the motor-side electrical path 25.

[0082] Next, the high-voltage charging mode of this embodiment will be described.

[0083] In the high-voltage charging mode, the control device 100 turns on the battery-to-battery switch 40 and each main switch SMRH, SMRL so that the first storage battery 31 and the second storage battery 32 are connected in series to the high-voltage charger 200, and turns off the positive electrode bypass switch 51, the motor-side switch 61, and the upper and lower arm switches SWH, SWL of the inverter 20.

[0084] Subsequently, the low-voltage charging mode will be described with reference to FIGS. 11 to 13.

[0085] First, mode 1 will be described with reference to FIG. 11. In mode 1, the control device 100 turns off the battery-to-battery switch 40, the motor-side switch 61, and the upper and lower arm switches SWH, SWL of the inverter 20, and turns on the positive electrode bypass switch 51 and each main switch SMRH, SMRL. As a result, as shown in FIG. 11, only the second storage battery 32 out of the first and second storage batteries 31 and 32 is charged by the low-voltage charger 210. In mode 1, the first storage battery 31 is not charged.

[0086] Next, Mode 2 will be described with reference to FIG. 12. In Mode 2, the control device 100 turns off the inter-battery switch 40 and the upper arm switch SWH of the inverter 20, and turns on at least one of the positive electrode bypass switch 51, the motor side switch 61, the high potential side main switch SMRH, and the lower arm switch SWL of at least one phase of the inverter 20. As a result, as shown in FIG. 12, only the first storage battery 31 out of the first and second storage batteries 31 and 32 is charged by the low-voltage charger 210. At this time, the charging current from the low-voltage charger 210 flows through the motor side electrical path 25, the armature winding 11, the conductive member 23, and the lower arm switch SWL. In Mode 2, the second storage battery 32 is not charged. Note that in Mode 2, the low potential side main switch SMRL may be either on or off.

[0087] Next, Mode 3 will be described with reference to FIG. 13. In Mode 3, the control device 100 turns off the inter-battery switch 40 and turns on the positive electrode bypass switch 51, the motor side switch 61, and the main switches SMRH and SMRL. In Mode 3, based on the detection values of the first and second current sensors 73 and 74 and the first and second voltage sensors 71 and 72, 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 outputting a charging current from the low-voltage charger 210 and alternately turning on the upper and lower arm switches SWH and SWL of at least one phase of the inverter 20, or by repeating the on / off of the lower arm switch SWL of at least one phase while turning off the upper arm switch SWH. Here, 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 period Tsw, the charging power of the first storage battery 31 and the second storage battery 32 can be adjusted individually. According to Mode 3, both the first and second storage batteries 31 and 32 can be charged.

[0088] Here, when charging the storage battery in the low-voltage charging mode with the motor-side switch 61 turned on, if the inter-terminal voltage of the first storage battery 31 is too high with respect to the inter-terminal voltage of the second storage battery 32, a closed circuit including the first storage battery 31, the positive electrode bypass switch 51, the lower-arm diode DL reversely connected in parallel to the lower-arm switch SWL, the armature winding 11, and the motor-side electrical path 25 is formed, and a phenomenon occurs in which current flows from the first storage battery 31 into the second storage battery 32.

[0089] Therefore, the control device 100 performs the charging process shown in FIG. 14 in the low-voltage charging mode. This process is repeatedly executed by the control device 100, for example, at a predetermined control cycle. Note that the process shown in FIG. 14 is assumed to be executed, for example, while the vehicle CA is stopped (a specific example is, for example, while parked).

[0090] In step S20, it is determined that the current timing is the charging start timing of the charging control period, and charging in the low-voltage charging mode is started.

[0091] In step S21, it is determined whether or not the absolute value of the difference between the second detection voltage VB and the first detection voltage VA is less than or equal to the determination threshold value ΔVjde.

[0092] If an affirmative determination is made in step S21, the process proceeds to step S22, and mode 3 shown in FIG. 13 is executed so as to maintain "VB≥VA" and "|VB - VA|≤ΔVjde".

[0093] In the subsequent step S23, it is determined whether or not the current timing is a specific timing. The specific timing is, for example, the timings of (A) to (E) above.

[0094] Note that the timing in (A) above may be the timing when the charging power Wоut to the second battery 32 among the output charging powers of the low-voltage charger 210 becomes greater than the allowable charging power Win of the second battery 32. Further, the timing in (E) above may be the timing when the charging rate of the second battery 32 becomes a value obtained by subtracting a predetermined charging rate from the target charging rates of the first and second batteries 31 and 32 at the charging end timing. The charging rate of the second battery 32 may be calculated based on the detection values of the second voltage sensor 72 and the second current sensor 74, for example.

[0095] If it is determined in step S23 that the current timing is not the specific timing, the process proceeds to step S21. On the other hand, if it is determined that the current timing is the specific timing, the process proceeds to step S27.

[0096] In step S27, a voltage adjustment process is performed during the period after the specific timing in the charging control period. Specifically, while maintaining "VB≧VA" and "|VB - VA|≦ΔVjde", mode 3 is executed so that the difference between the first and second detected voltages VA and VB at the charging end timing of the charging control period becomes smaller than the difference between the first and second detected voltages VA and VB at the specific timing. Also, mode 3 is executed so that the charging current IA of the first battery 31 is larger than the charging current IB of the second battery 32.

[0097] In step S28, it is determined whether the current timing has reached the charging end timing. The process of step S27 is continued until an affirmative determination is made in step S28.

[0098] Incidentally, at the charging start timing, there may be a case where the voltage between the terminals of the second battery 32 and the voltage between the terminals of the first battery 31 are significantly different. In this case, a negative determination is made in step S21, and prior to the execution of the voltage adjustment process in step S21, a pre-charging process is performed in steps S24 to S26 to reduce the difference between the first and second detected voltages VA and VB. Specifically, first, in step S24, it is determined whether the first detected voltage VA is higher than the second detected voltage VB.

[0099] If it is determined in step S24 that the first detection voltage VA is higher than the second detection voltage VB, the process proceeds to step S25. In other words, if it is determined that the second detection voltage VB is lower than the value obtained by subtracting the determination threshold ΔVjde from the first detection voltage VA, the process proceeds to step S25. In step S25, a mode 1 is executed in which only the second battery 32 out of the first and second batteries 31 and 32 is charged with the low-voltage charger 210 so that the absolute value of the difference between the first and second detection voltages VA and VB becomes equal to or less than the determination threshold ΔVjde (see FIG. 11). Then, the process proceeds to step S23. Note that in step S25, mode 1 may be further executed so that "VB≧VA".

[0100] On the other hand, if it is determined in step S24 that the first detection voltage VA is lower than the second detection voltage VB, the process proceeds to step S26. In step S26, a mode 2 is executed in which only the first battery 31 out of the first and second batteries 31 and 32 is charged with the low-voltage charger 210 so that the absolute value of the difference between the first and second detection voltages VA and VB becomes equal to or less than the determination threshold ΔVjde (see FIG. 12). Then, the process proceeds to step S23. Note that in step S26, mode 2 may be further executed so that "VB≧VA".

[0101] Also, in step S26, mode 3 may be executed instead of mode 2. Specifically, mode 3 may be executed so that the charging current of the first battery 31 becomes larger than that of the second battery 32 and the absolute value of the difference between the first and second detection voltages VA and VB becomes equal to or less than the determination threshold ΔVjde.

[0102] According to the present embodiment described above, the same effects as those of the first embodiment can be obtained.

[0103] <Other Embodiments> Note that each of the above embodiments may be implemented with the following modifications.

[0104] · In steps S22, S25 to S27 of FIG. 14 in the second embodiment, if the relationship of "|VB - VA| ≦ ΔVjde" is maintained, "VB < VA" may be satisfied.

[0105] · The configuration of the power conversion device may be the configuration described below.

[0106] As shown in FIG. 15, in the configuration shown in FIG. 1 above, the motor-side switch 60 may not be provided in the motor-side electric path 25.

[0107] As shown in FIG. 16, in the configuration shown in FIG. 10 above, the motor-side switch 61 may not be provided in the motor-side electric path 25.

[0108] As shown in FIG. 17, in the configuration shown in FIG. 1 above, the positive electrode bypass switch 51 may be further provided. In this case, in the high-voltage charging mode and the process shown in FIG. 6 above, for example, the positive electrode bypass switch 51 may be turned off.

[0109] As shown in FIG. 18, in the configuration shown in FIG. 17 above, the motor-side switch 60 may not be provided in the motor-side electric path 25.

[0110] As shown in FIG. 19, in the configuration shown in FIG. 10 above, the negative electrode bypass switch 50 may be further provided. In this case, in the high-voltage charging mode and the process shown in FIG. 14 above, for example, the negative electrode bypass switch 50 may be turned off.

[0111] As shown in FIG. 20, in the configuration shown in FIG. 19 above, the motor-side switch 61 may not be provided in the motor-side electric path 25.

[0112] As shown in FIG. 21, as the motor-side switch, in addition to the switch connecting the neutral point of the armature winding 11 and the negative electrode terminal of the first storage battery 31, a switch connecting the neutral point of the armature winding 11 and the positive electrode terminal of the second storage battery 32 may be provided.

[0113] Specifically, the first end of the common path 26 is connected to the neutral point of the armature winding 11. The first end of the first electrical path 27 is connected to the second end of the common path 26, and the second end of the battery-to-battery electrical path 24 closer to the second battery 32 than the battery-to-battery switch 40 is connected to the second end of the first electrical path 27. Further, the first end of the second electrical path 28 is connected to the second end of the common path 26, and the first end of the battery-to-battery electrical path 24 closer to the first battery 31 than the battery-to-battery switch 40 is connected to the second end of the second electrical path 28. 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. Note that the common path 26 may not be provided, and the first ends of the first electrical path 27 and the second electrical path 28 may be connected to the neutral point of the armature winding 11, respectively.

[0114] Note that in the configuration shown in FIG. 21, in the high-voltage charging mode and the process shown in FIG. 6 above, for example, the positive electrode bypass switch 51 and the second motor-side switch 61 may be turned off. Further, in the configuration shown in FIG. 21, in the high-voltage charging mode and the process shown in FIG. 14 above, for example, the negative electrode bypass switch 50 and the first motor-side switch 60 may be turned off.

[0115] As shown in FIG. 22, in the configuration shown in FIG. 21 above, the first motor-side switch 60 may not be provided in the first electrical path 27.

[0116] As shown in FIG. 23, in the configuration shown in FIG. 21 above, the second motor-side switch 61 may not be provided in the second electrical path 28.

[0117] As shown in FIG. 24, in the configuration shown in FIG. 22 above, the positive electrode bypass switch 51 may not be provided.

[0118] As shown in FIG. 25, in the configuration shown in FIG. 21 above, the positive electrode bypass switch 51 may not be provided.

[0119] As shown in FIG. 26, in the configuration shown in the previous FIG. 23, the negative electrode bypass switch 50 may not be provided.

[0120] As shown in FIG. 27, in the configuration shown in the previous FIG. 21, the negative electrode bypass switch 50 may not be provided.

[0121] · As shown in FIG. 28, a third current sensor 75 may be provided in a portion of the high-potential side electric path 22H on the charging switch DCRH side that is at a higher potential than the inverter 20. Also, a fourth current sensor 76 can be provided at an arbitrary position in the motor side electric path 25. For example, the fourth current sensor 76 may be provided on the neutral point side of the motor side switch 60 in the motor side electric path 25. Here, among the first to fourth current sensors 73 to 76, at least two or more current sensors may be provided. Thereby, it becomes possible to perform charge control of each of the storage batteries 31 and 32 with as few current sensors as possible. Also, a current sensor for detecting the current flowing through each conductive member 23 may be provided, and instead of the detection value of the fourth current sensor 76, the total value of the current detection values flowing through each conductive member 23 may be used.

[0122] · The connection destination of the motor side electric path 25 is not limited to the neutral point of the armature winding 11. For example, as shown in FIG. 29, it may be an intermediate portion of the armature winding 11.

[0123] Also, the connection destination of the motor side electric path 25 may be, for example, a conductive member 23 as shown in FIG. 30. In this case, as the switching of the inverter 20 in steps S12 and S17 in the previous FIG. 6, as shown in FIG. 31, among each phase, the upper and lower arm switches SWH and SWL of the phase to which the motor side electric path 25 is connected to the conductive member 23 are turned off, and the upper and lower arm switches SWH and SWL in at least one phase other than the phase to which the motor side electric path 25 is connected to the conductive member 23 are alternately turned on for switching.

[0124] · As shown in FIG. 32, a high-potential side charging switch DCRH and a positive electrode side connection part may be provided on the first battery 31 side of the high-potential side main switch SMRH in the high-potential side electrical path 22H, and a low-potential side charging switch DCRL and a negative electrode side connection part may be provided on the second battery 32 side of the low-potential side main switch SMRL in the low-potential side electrical path 22L.

[0125] · The positive electrode terminal of the first battery 31 and the high-potential side electrical path 22H may be connected by a first fuse. Also, the negative electrode terminal of the second battery 32 and the low-potential side electrical path 22L may be connected by a second fuse.

[0126] · Each of the main switches SMRH, SMRL, each of the charging switches DCRH, DCRL, the inter-battery switch 40, the bypass switch, and the motor-side switch is not limited to being composed of one switch, and may be composed of a series connection body of a plurality of switches or a parallel connection body of a plurality of switches.

[0127] · The switch of the inverter 20 is not limited to an IGBT with a freewheel diode connected in anti-parallel, and may be, for example, an N-channel MOSFET having a body diode. In this case, the high-potential side terminal of the N-channel MOSFET becomes the drain, and the low-potential side terminal becomes the source.

[0128] · The motor is not limited to being star-connected, and may be delta-connected. Also, the motor and the inverter are not limited to three-phase ones, and may be two-phase ones, or four-phase or more ones. Also, the motor is not limited to a permanent magnet type synchronous machine having a permanent magnet as a field pole on the rotor, and may be a wound field type synchronous machine having a field winding as a field pole on the rotor. In this case, both a field winding and a permanent magnet may be provided on the rotor. Also, the motor is not limited to a synchronous machine, and may be an induction machine.

[0129] · As the power storage unit to be charged by an external charger, it is not limited to a storage battery. For example, it may be a large-capacity electric double-layer capacitor, or one that includes both a storage battery and an electric double-layer capacitor.

[0130] · The moving body on which the power conversion device is mounted is not limited to a vehicle. For example, it may be an aircraft or a ship. Further, the mounting destination of the power conversion device is not limited to a moving body and may be a stationary device.

[0131] · The control unit and its method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and its method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Or, the control unit and its method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured by one or more hardware logic circuits. Further, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer.

[0132] Although the present disclosure has been described in accordance with the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also includes various modifications and modifications within the equivalent scope. In addition, various combinations and forms, and further other combinations and forms including only one element, more than one, or less than one of them, are within the scope and thinking scope of the present disclosure.

Claims

1. A high-potential-side electrical path (22H) electrically connectable to the positive electrode terminal of the first power storage unit (31) and the positive electrode terminal of the external charger (200, 210); A low-potential-side electrical path (22L) electrically connectable to the negative electrode terminal of the second power storage unit (32) and the negative electrode terminal of the external charger; 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 power storage unit and the positive electrode terminal of the second power storage unit; A bypass switch (50, 51) that makes at least one of the electrical connections between the negative electrode terminals of the first power storage unit and the second power storage unit and the electrical connections between the positive electrode terminals of the first power storage unit and the second power storage unit; A motor-side electrical path (25 - 28) that electrically connects the armature winding or the conductive member and the inter-storage-unit electrical path; A control unit (100); Comprising: The control unit: With the inter-storage-unit switch turned off and the bypass switch turned on, starts charging at least one of the first power storage unit and the second power storage unit with the external charger; After the start of charging by the external charger, performs a voltage adjustment process, which is a switching process of the inverter for making the voltage difference between the first power storage unit and the second power storage unit equal to or less than a determination threshold value. A power conversion device.

2. The bypass switch is a negative electrode-to-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 is a path (25 - 27) that electrically connects the armature winding and the side of the inter-storage-unit electrical path closer to the second power storage unit than the inter-storage-unit switch. The power conversion device according to Claim 1.

3. The voltage adjustment process is a switching process of the inverter for making the voltage difference equal to or less than the determination threshold value and making the voltage of the first power storage unit equal to or higher than the voltage of the second power storage unit. The power conversion device according to Claim 2.

4. Before executing the voltage adjustment process, if the control unit determines that the voltage of the first power storage unit is lower than the value obtained by subtracting the determination threshold from the voltage of the second power storage unit, the power conversion device according to claim 3, which performs a pre-charging process of charging only the first power storage unit among the first power storage unit and the second power storage unit by the external charger with the inter-storage unit switch turned off and the negative electrode bypass switch turned on so that the voltage difference becomes equal to or less than the determination threshold.

5. Before executing the voltage adjustment process, if the control unit determines that the voltage of the second power storage unit is lower than the value obtained by subtracting the determination threshold from the voltage of the first power storage unit, the power conversion device according to claim 3, which performs a pre-charging process of charging only the second power storage unit among the first power storage unit and the second power storage unit by the external charger with the inter-storage unit switch and the negative electrode bypass switch turned off and the upper arm switch turned on so that the voltage difference becomes equal to or less than the determination threshold.

6. Before executing the voltage adjustment process, if the control unit determines that the voltage of the second power storage unit is lower than the voltage of the first power storage unit or the voltage difference between the first power storage unit and the second power storage unit is equal to or less than the determination threshold, the power conversion device according to claim 3, which performs a pre-charging process of outputting a charging current from the external charger while performing switching of the inverter with the inter-storage unit switch turned off and the negative electrode bypass switch turned on so that the charging power of the second power storage unit becomes larger than that of the first power storage unit and the voltage difference becomes equal to or less than the determination threshold.

7. The control unit outputs a charging current from the external charger during a charging control period from a charging start timing to a charging end timing, performs the pre-charging process in a period before a specific timing which is a timing between the charging start timing and the charging end timing in the charging control period, The voltage adjustment process in the period after the specific timing in the charging control period is a switching process of the inverter that makes the charging power of the second power storage unit larger than the charging power of the first power storage unit so that the voltage difference at the charging end timing is smaller than the voltage difference at the specific timing, according to any one of claims 4 to 6.

8. The power conversion device according to claim 7, wherein the specific timing is a timing at which the charging power to the first power storage unit among the charging power output from the external charger becomes greater than the allowable charging power of the first power storage unit.

9. The power conversion device according to claim 7, wherein the specific timing is a timing at which the charging mode by the external charger switches from a constant current mode to a constant voltage mode or a constant power mode.

10. The power conversion device according to claim 7, wherein the specific timing is a timing a predetermined period before the charging end timing.

11. The power conversion device according to claim 7, wherein the specific timing is a timing at which the current charging rate of the first power storage unit becomes a value obtained by subtracting a predetermined charging rate from the target charging rates of the first power storage unit and the second power storage unit at the charging end timing.

12. The bypass switch is a positive electrode bypass switch (51) that electrically connects the positive electrode terminal of the first power storage unit and the positive electrode terminal of the second power storage unit. The motor-side electrical path is a path (25, 26, 28) that electrically connects the armature winding and the side of the first power storage unit among the electrical paths between the power storage units, closer to the first power storage unit than the switch between the power storage units. The power conversion device according to claim 1.

13. The voltage adjustment process is a switching process of the inverter for making the voltage difference equal to or less than the determination threshold value and making the voltage of the second power storage unit equal to or higher than the voltage of the first power storage unit. The power conversion device according to claim 12.

14. Before executing the voltage adjustment process, when the control unit determines that the voltage of the second power storage unit is lower than a value obtained by subtracting the determination threshold value from the voltage of the first power storage unit, the control unit turns off the switch between the power storage units and turns on the positive electrode bypass switch, and performs a pre-charging process of charging only the second power storage unit among the first power storage unit and the second power storage unit with the external charger so that the voltage difference becomes equal to or less than the determination threshold value. The power conversion device according to claim 13.

15. Before the voltage adjustment process is executed, when the control unit determines that the voltage of the first power storage unit is lower than the value obtained by subtracting the determination threshold from the voltage of the second power storage unit, the control unit turns off the inter-storage unit switch and the positive electrode bypass switch and turns on the lower arm switch, and performs a pre-charging process of charging only the first power storage unit among the first power storage unit and the second power storage unit with the external charger so that the voltage difference becomes equal to or less than the determination threshold. The power conversion device according to claim 13.

16. Before the voltage adjustment process is executed, when the control unit determines that the voltage of the first power storage unit is lower than the voltage of the second power storage unit or the voltage difference between the second power storage unit and the first power storage unit is equal to or less than the determination threshold, the control unit turns off the inter-storage unit switch and turns on the positive electrode bypass switch, and while outputting a charging current from the external charger so that the charging power of the first power storage unit becomes larger than that of the second power storage unit and the voltage difference becomes equal to or less than the determination threshold, performs a pre-charging process of performing switching of the inverter. The power conversion device according to claim 13.

17. The control unit outputs a charging current from the external charger during a charging control period from a charging start timing to a charging end timing, performs the pre-charging process in a period before a specific timing which is a timing between the charging start timing and the charging end timing in the charging control period, the voltage adjustment process in the period after the specific timing in the charging control period is a switching process of the inverter that makes the charging power of the first power storage unit larger than the charging power of the second power storage unit so that the voltage difference at the charging end timing becomes smaller than the voltage difference at the specific timing. The power conversion device according to any one of claims 14 to 16.

18. The specific timing is a timing at which the charging power to the second power storage unit among the charging powers output from the external charger becomes larger than the allowable charging power of the second power storage unit. The power conversion device according to claim 17.

19. The specific timing is a timing at which the charging mode by the external charger switches from a constant current mode to a constant voltage mode or a constant power mode. The power conversion device according to claim 17.

20. The power conversion device according to claim 17, wherein the specific timing is a timing that is a predetermined period before the charging end timing.

21. The power conversion device according to claim 17, wherein the specific timing is a timing at which the current charging rate of the second power storage unit becomes a value obtained by subtracting a predetermined charging rate from the target charging rates of the first power storage unit and the second power storage unit at the charging end timing.

22. A high-potential side electrical path (22H) electrically connectable to the positive electrode terminal of the first power storage unit (31) and the positive electrode terminal of the external charger (200, 210), A low-potential side electrical path (22L) electrically connectable to the negative electrode terminal of the second power storage unit (32) and the negative electrode terminal of the external charger, 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), In a program applied to a power conversion device including The power conversion device, 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 power storage unit and the positive electrode terminal of the second power storage unit, A bypass switch (50, 51) that makes at least one of the electrical connections between the negative electrode terminals of the first power storage unit and the second power storage unit and the electrical connections between the positive electrode terminals of the first power storage unit and the second power storage unit, A motor-side electrical path (25 to 28) that electrically connects the armature winding or the conductive member and the inter-storage unit electrical path, Comprising To the computer, A process of starting to charge at least one of the first power storage unit and the second power storage unit with the external charger in a state where the inter-storage unit switch is turned off and the bypass switch is turned on, A voltage adjustment process that is a switching process of the inverter for making the voltage difference between the first power storage unit and the second power storage unit equal to or less than a determination threshold after the start of charging by the external charger, A program that causes the above to be executed.

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