Power Conversion Device

Abstract

To provide a power conversion device capable of reducing a current capacity of a switch.SOLUTION: In a power conversion device 10, a neutral point line Lm and a third positive electrode side terminal C3p of a charge inlet 62 are connected by a third high potential side line L3p, and a negative electrode side main line Ln and a third negative electrode side terminal C3n of the charge inlet 62 are connected by a third low potential side line L3n. The third high potential side line L3p is connected to a portion closer to a battery pack 20 than a neutral point switch SWm in the neutral point line Lm, and the third low potential side line L3n is connected to a portion closer to the battery pack 20 than a negative electrode side switch SWn in the negative electrode side main line Ln.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power conversion device including a storage device having a first storage unit and a second storage unit connected in series to the negative electrode side of the first storage unit, an inverter having upper and lower arm switches, and a rotating electric machine having windings connected to the inverter. [Background technology]

[0002] As described in Patent Document 1, a known device of this type includes a positive main path, a negative main path, a neutral path, and a neutral switch provided in the neutral path. The positive main path connects the high potential terminal of the upper arm switch to the positive side of the first power storage unit. The negative main path connects the low potential terminal of the lower arm switch to the negative side of the second power storage unit. The neutral path connects the battery connection point between the negative side of the first power storage unit and the positive side of the second power storage unit to the neutral point of the winding.

[0003] In this power conversion device, when the neutral point switch is turned on, switching control of the upper and lower arm switches constituting the inverter causes a current to flow between the first and second power storage units through the neutral point path, the neutral point of the winding, and the inverter, thereby equalizing the voltages of the first and second power storage units and raising the temperatures of the first and second power storage units, for example. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-120566 Summary of the Invention [Problem to be solved by the invention]

[0005] An electric device may be provided that is connected to any two of the neutral path, the positive main path, and the negative main path, and power is transmitted between the electric device and the power storage device.

[0006] When power is transmitted between an electrical device and a power storage device, switching control of the upper and lower arm switches may cause a current to flow between the first and second power storage units that constitute the power storage device. In this case, the current flowing through the switch is a combination of the current flowing between the electrical device and the power storage device and the current flowing as a result of the execution of the switching control, so the current capacity of the switch must be increased. However, this increases the size and cost of the switch.

[0007] A main object of the present invention is to provide a power conversion device capable of reducing the current capacity of the switches. [Means for solving the problem]

[0008] The present invention provides a power storage device including a first power storage unit and a second power storage unit connected in series to a negative electrode side of the first power storage unit; an inverter having upper and lower arm switches; a rotating electric machine having a winding connected to the inverter; a positive main path connecting a high potential side terminal of the upper arm switch and a positive side of the first power storage unit; a negative main path connecting a low potential side terminal of the lower arm switch and a negative side of the second power storage unit; a neutral point path connecting a battery connection point between a negative electrode side of the first power storage unit and a positive electrode side of the second power storage unit and a neutral point of the winding; switches provided in the positive main path, the negative main path, and the neutral path; an electrical device having a first connection terminal and a second connection terminal; a first connection path that connects a first target path, which is any one of the positive main path, the negative main path, and the neutral point path, to the first connection terminal; a second connection path connecting a second target path, which is any one of the positive main path, the negative main path, and the neutral point path other than the first target path, to the second connection terminal; At least one of the following configurations is used: the first connection path is connected to the power storage device side of the switch among the first target path; and the second connection path is connected to the power storage device side of the switch among the second target path.

[0009] When the first connection path is connected to the power storage device side of the switch in the first target path, the power storage device and the electrical device are electrically connected without passing through the switch provided in the first target path, which reduces the current capacity of the switch provided in the first target path.

[0010] Furthermore, when a configuration is used in which the second connection path is connected to the power storage device side of the switch in the second target path, the power storage device and the electrical device are electrically connected without going through the switch provided in the second target path, which allows the current capacity of the switch provided in the first target path to be reduced. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram of a power conversion device according to a first embodiment. [Figure 2] 4 is a flowchart of a process executed by a control device. [Figure 3] 10 is a flowchart of a process executed by a control device according to a modification of the first embodiment. [Figure 4] FIG. 10 is a configuration diagram of a power conversion device according to a second embodiment. [Figure 5] FIG. 10 is a configuration diagram of a power conversion device according to a third embodiment. [Figure 6] FIG. 10 is a configuration diagram of a power conversion device according to a fourth embodiment. [Figure 7] FIG. 10 is a configuration diagram of a power conversion device according to a fifth embodiment. [Figure 8] FIG. 10 is a configuration diagram of a power conversion device according to a sixth embodiment. [Figure 9] FIG. 13 is a configuration diagram of a power conversion device according to a seventh embodiment. [Figure 10] FIG. 13 is a configuration diagram of a power conversion device according to an eighth embodiment. [Figure 11] FIG. 13 is a configuration diagram of a power conversion device according to a ninth embodiment. [Figure 12] FIG. 20 is a configuration diagram of a power conversion device according to a tenth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] First Embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a power converter according to the present invention will now be described with reference to the drawings. The power converter of this embodiment is mounted on a vehicle such as an electric vehicle or a hybrid vehicle.

[0013] As shown in Fig. 1, the power conversion device 10 includes an inverter 30 and a rotating electric machine 40. The rotating electric machine 40 is a three-phase synchronous machine and includes star-connected U-, V-, and W-phase windings 41U, 41V, and 41W. The phase windings 41U, 41V, and 41W are arranged with an electrical angle of 120°. The rotating electric machine 40 is, for example, a permanent magnet synchronous machine. In this embodiment, the rotating electric machine 40 is an on-board main engine and serves as a power source for running the vehicle.

[0014] The inverter 30 includes three phases of series-connected upper-arm switches QUH, QVH, and QWH and lower-arm switches QUL, QVL, and QWL. In this embodiment, voltage-controlled semiconductor switching elements, specifically IGBTs, are used as the switches QUH, QVH, QWH, QUL, QVL, and QWL. Therefore, the high-potential terminal of each switch QUH, QVH, QWH, QUL, QVL, and QWL is the collector, and the low-potential terminal is the emitter. Diodes DUH, DVH, DWH, DUL, DVL, and DWL, serving as freewheeling diodes, are connected in inverse parallel to each switch QUH, QVH, QWH, QUL, QVL, and QWL.

[0015] A first end of a U-phase winding 41U is connected to the emitter of the U-phase upper arm switch QUH and the collector of the U-phase lower arm switch QUL via a U-phase conductive member 32U. A first end of a V-phase winding 41V is connected to the emitter of the V-phase upper arm switch QVH and the collector of the V-phase lower arm switch QVL via a V-phase conductive member 32V. A first end of a W-phase winding 41W is connected to the emitter of the W-phase upper arm switch QWH and the collector of the W-phase lower arm switch QWL via a W-phase conductive member 32W. Second ends of the U-, V-, and W-phase windings 41U, 41V, and 41W are connected to each other at a neutral point O. Each conductive member 32U to 32W is, for example, a bus bar or a cable. In this embodiment, the phase windings 41U, 41V, and 41W have the same number of turns. As a result, the phase windings 41U, 41V, and 41W are set to have the same inductance, for example.

[0016] The collectors of the upper arm switches QUH, QVH, and QWH are connected to the positive terminal of the battery pack 20 by a positive main path Lp. The emitters of the lower arm switches QUL, QVL, and QWL are connected to the negative terminal of the battery pack 20 by a negative main path Ln. In this embodiment, the negative main path Ln corresponds to the "second target path."

[0017] The power conversion device 10 includes a capacitor 31. The capacitor 31 connects the collectors of the upper-arm switches QUH, QVH, and QWH to the emitters of the lower-arm switches QUL, QVL, and QWL. The capacitor 31 may be built into the inverter 30 or may be provided outside the inverter 30.

[0018] The battery pack 20 corresponds to an "electricity storage device" and is configured as a series connection of battery cells, which are single cells. In this embodiment, the terminal voltages (e.g., rated voltages) of the battery cells constituting the battery pack 20 are set to be the same. For example, secondary batteries such as lithium ion batteries can be used as the battery cells. The battery pack 20 is provided, for example, outside the power conversion device 10.

[0019] In this embodiment, among the battery cells constituting the battery pack 20, a series connection of multiple battery cells on the high potential side constitutes the first storage battery 21 (corresponding to the "first power storage unit"), and a series connection of multiple battery cells on the low potential side constitutes the second storage battery 22 (corresponding to the "second power storage unit"). In other words, the battery pack 20 is divided into two blocks. In this embodiment, the number of battery cells constituting the first storage battery 21 is the same as the number of battery cells constituting the second storage battery 22. Therefore, the terminal voltage (e.g., rated voltage) of the first storage battery 21 is the same as the terminal voltage (e.g., rated voltage) of the second storage battery 22. In this embodiment, the rated voltages of the first storage battery 21 and the second storage battery 22 are each 400 V. Therefore, the rated voltage of the battery pack 20 is 800 V. In the battery pack 20, an intermediate terminal B (equivalent to the "battery connection point") is connected to the negative terminal of the first storage battery 21 and the positive terminal of the second storage battery 22.

[0020] The power conversion device 10 includes a monitoring unit 50. The monitoring unit 50 monitors the terminal voltage, SOC, SOH, temperature, etc. of each battery cell that constitutes the battery pack 20. The monitoring information of the monitoring unit 50 is input to a control device 90 that the power conversion device 10 includes.

[0021] The power conversion device 10 includes a neutral point path Lm and a neutral point switch SWm. The neutral point path Lm electrically connects an intermediate terminal B and a neutral point O of the battery pack 20. The neutral point switch SWm is provided in the neutral point path Lm. In this embodiment, the neutral point switch SWm is a relay. When the neutral point switch SWm is turned on, the intermediate terminal B and the neutral point O are electrically connected. On the other hand, when the neutral point switch SWm is turned off, the intermediate terminal B and the neutral point O are electrically disconnected. In this embodiment, the neutral point path Lm corresponds to a "first target path."

[0022] The power conversion device 10 includes a positive switch SWp and a negative switch SWn. In this embodiment, the positive switch SWp and the negative switch SWn are relays.

[0023] The positive switch SWp is provided in the positive main path Lp. When the positive switch SWp is turned on, the positive terminal of the first storage battery 21 and the collectors of each of the upper arm switches QUH, QVH, and QWH are electrically connected. On the other hand, when the positive switch SWp is turned off, the positive terminal of the first storage battery 21 and the collectors of each of the upper arm switches QUH, QVH, and QWH are electrically disconnected.

[0024] The negative switch SWn is provided on the negative main path Ln. When the negative switch SWn is turned on, the negative terminal of the second storage battery 22 and the emitters of the lower arm switches QUL, QVL, and QWL are electrically connected. On the other hand, when the negative switch SWn is turned off, the negative terminal of the second storage battery 22 and the emitters of the lower arm switches QUL, QVL, and QWL are electrically disconnected.

[0025] The power conversion device 10 includes, as electrical devices, an auxiliary device 60, a charger 61, and a charging inlet 62. The power conversion device 10 also includes, as components for electrically connecting the electrical devices to the battery pack 20, a first high potential side path L1p, a first low potential side path L1n, a first cutoff switch SW1, a second high potential side path L2p, a second low potential side path L2n, a second cutoff switch SW2, a third high potential side path L3p, a third low potential side path L3n, and a third cutoff switch SW3. In this embodiment, each of the cutoff switches SW1 to SW3 is a relay.

[0026] The auxiliary device 60 includes a first positive terminal C1p and a first negative terminal C1n. A first end of a first high potential path L1p is connected to the first positive terminal C1p. A second end of the first high potential path L1p is connected to a portion of the neutral point path Lm that is closer to the intermediate terminal B than the neutral point switch SWm. A first end of a first low potential path L1n is connected to the first negative terminal C1n. A second end of the first low potential path L1n is connected to a portion of the negative main path Ln that is closer to the second storage battery 22 than the negative switch SWn. A first cutoff switch SW1 is provided in the first low potential path L1n. When the first cutoff switch SW1 is turned on, power can be supplied from the second storage battery 22 to the auxiliary device 60.

[0027] The auxiliary equipment 60 includes a DC-DC converter, an air conditioning inverter, and an air conditioning heater. The DC-DC converter is driven to step down the output voltage of the second storage battery 22 and supply it to a low-voltage storage battery (not shown). The low-voltage storage battery is, for example, a lead-acid battery with a rated voltage of 12 V. The air conditioning inverter drives an electric compressor that circulates refrigerant in a refrigeration cycle. The air conditioning heater is driven to heat the vehicle interior.

[0028] The charger 61 includes a second positive terminal C2p and a second negative terminal C2n. A first end of a second high potential path L2p is connected to the second positive terminal C2p. A second end of the second high potential path L2p is connected to a portion of the neutral point path Lm that is closer to the intermediate terminal B than the neutral point switch SWm. A first end of a second low potential path L2n is connected to the second negative terminal C2n. A second end of the second low potential path L2n is connected to a portion of the negative main path Ln that is closer to the second storage battery 22 than the negative switch SWn.

[0029] A charging connector connected to an AC power source 71 provided in a house or the like can be connected to the charger 61. The charging connector is connected to the charger 61 by, for example, a user. When the charging connector is connected to the charger 61 and the second cutoff switch SW2 is turned on, the charger 61 converts the AC voltage output from the AC power source 71 into a DC voltage and supplies the DC voltage to the second storage battery 22. The charger 61 is also called an on-board charger (OBC). On the other hand, the safety of the user is ensured by turning off the second cutoff switch SW2.

[0030] The charging inlet 62 includes a third positive terminal C3p and a third negative terminal C3n. A first end of a third high potential path L3p is connected to the third positive terminal C3p. A second end of the third high potential path L3p is connected to a portion of the neutral point path Lm that is closer to the intermediate terminal B than the neutral point switch SWm. A first end of a third low potential path L3n is connected to the third negative terminal C3n. A second end of the third low potential path L3n is connected to a portion of the negative main path Ln that is closer to the second storage battery 22 than the negative switch SWn.

[0031] A charging connector connected to an external charger 72 (corresponding to a "charging facility") provided outside the vehicle can be connected to charging inlet 62. The charging connector is connected to charging inlet 62, for example, by a user. External charger 72 converts AC voltage (for example, single-phase or three-phase AC voltage) supplied from a system power supply into DC voltage. When the charging connector is connected to charging inlet 62 and third cutoff switch SW3 is turned on, a charging current is supplied from external charger 72 to second storage battery 22 via charging inlet 62. On the other hand, turning off third cutoff switch SW3 ensures the safety of the user.

[0032] In this embodiment, the first to third positive terminals C1p to C3p correspond to the “first connection terminals,” and the first to third negative terminals C1n to C3n correspond to the “second connection terminals.” Furthermore, the first to third high potential paths L1p to L3p correspond to the “first connection paths,” and the first to third low potential paths L1n to L3n correspond to the “second connection paths.”

[0033] The power conversion device 10 includes a current sensor 80 and a phase current sensor 81. The current sensor 80 detects the current flowing through the neutral point path Lm. The phase current sensor 81 detects phase currents for at least two phases. The phase current sensor 81 detects, for example, the currents flowing through the conductive members for at least two phases among the conductive members 32U to 32W. The detection values ​​of the current sensors 80 and 81 are input to the control device 90.

[0034] The control device 90 is primarily composed of a microcomputer 90a, which includes a CPU. The functions provided by the microcomputer 90a can be provided by software stored in a physical memory device and a computer executing the software, software alone, hardware alone, or a combination thereof. For example, if the microcomputer 90a 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 90a executes a program stored in a non-transitory tangible storage medium serving as a storage unit. The program includes, for example, programs for voltage equalization control, temperature rise control, and the control shown in Figures 2 and 3, which will be described later. Execution of the program results in the execution of a method corresponding to the program. The storage unit is, for example, a non-volatile memory. The program stored in the storage unit can be updated, for example, via a communication network such as the Internet.

[0035] The control device 90 performs switching control of each switch QUH to QWL constituting the inverter 30 based on the detected value of the phase current sensor 81, etc., to feedback control the control variable of the rotary electric machine 40 to a command value. In this embodiment, the control variable is torque. In each phase, the upper arm switch and the lower arm switch are alternately turned on.

[0036] The control device 90 turns on or off the neutral point switch SWm, the positive switch SWp, the negative switch SWn, and the first to third cutoff switches SW1 to SW3, and is capable of communicating with the monitoring unit 50.

[0037] The control device 90 functions as a "control unit" that performs temperature rise control and voltage equalization control with the neutral point switch SWm, the positive side switch SWp, and the negative side switch SWn turned on. The temperature rise control is switching control of the inverter 30 to flow AC current between the first storage battery 21 and the second storage battery 22 via the neutral point path Lm, the neutral point O, and the inverter 30. This control raises the temperature of the battery pack 20. The voltage equalization control is switching control of the inverter 30 to flow DC current from one of the first storage battery 21 and the second storage battery 22 to the other via the neutral point path Lm, the neutral point O, and the inverter 30. This control supplies energy from one of the first storage battery 21 and the second storage battery 22 to the other, thereby equalizing the voltages of the first storage battery 21 and the second storage battery 22.

[0038] The control device 90 calculates a neutral point command current for temperature rise control or voltage equalization control. The neutral point command current for temperature rise control is an AC component, and the neutral point command current for voltage equalization control is a DC component. The control device 90 performs switching control of the inverter 30 to adjust the current detected by the current sensor 80 to the neutral point command current. The control device 90 can also perform temperature rise control and voltage equalization control simultaneously. In this case, the neutral point command current is the sum of the AC component and the DC component. Furthermore, when the control device 90 does not perform temperature rise control or voltage equalization control but instead controls the controlled variable of the rotating electric machine 40 to run the vehicle, it turns on the positive side switch SWp and the negative side switch SWn and turns off the neutral point switch SWm.

[0039] Fig. 2 shows a flowchart of the processing performed by the control device 90. In the example shown in Fig. 2, it is assumed that the vehicle is stopped and the positive switch SWp and the negative switch SWn are turned on.

[0040] In step S10, it is determined whether or not there is an instruction to charge the second storage battery 22 via the charger 61. For example, if it is determined that the charging connector of the AC power supply 71 is connected to the charger 61, it may be determined that there is an instruction to charge.

[0041] If it is determined in step S10 that a charge instruction has been issued, the process proceeds to step S11, where the second shutoff switch SW2 is turned on and the first shutoff switch SW1 and the third shutoff switch SW3 are turned off.

[0042] In the following step S12, it is determined whether or not there is an instruction to execute at least one of the temperature increase control and the voltage equalization control.

[0043] If it is determined in step S12 that there are no instructions to execute both the temperature increase control and the voltage equalization control, the process proceeds to step S13, where the neutral point switch SWm is turned off, and in step S14, the charger 61 is controlled to charge the second storage battery 22.

[0044] On the other hand, if it is determined in step S12 that an instruction to execute at least one of the temperature rise control and the voltage equalization control has been issued, the process proceeds to step S15, where the neutral point switch SWm is turned on. Then, in step S16, the charger 61 is controlled to charge the second storage battery 22. The temperature rise control or the voltage equalization control that has been instructed to be executed is executed.

[0045] Current flows through the neutral point switch SWm, the positive side switch SWp, and the negative side switch SWn when at least one of the temperature rise control and the voltage equalization control is performed. On the other hand, most of the charging current supplied from the charger 61 flows to the second storage battery 22, and almost none of the charging current supplied from the charger 61 flows through the neutral point switch SWm and the negative side switch SWn. This is because the second high potential side path L2p is connected to a portion of the neutral point path Lm that is closer to the intermediate terminal B than the neutral point switch SWm, and the second low potential side path L2n is connected to a portion of the negative side main path Ln that is closer to the second storage battery 22 than the negative side switch SWn. This allows the current capacities of the neutral point switch SWm and the negative side switch SWn to be reduced.

[0046] A surge voltage occurs when at least one of the temperature rise control and the voltage equalization control is performed. In this embodiment, the first shutoff switch SW1 and the third shutoff switch SW3 are turned off when this switching control is performed. This prevents the surge voltage from being transmitted to the auxiliary device 60 and the charging inlet 62. This prevents breakdowns in the auxiliary device 60 and the charging inlet 62.

[0047] If it is determined in step S10 that there is no charge instruction, the process proceeds to step S17, where it is determined whether there is a charge instruction for the second storage battery 22 via the charge inlet 62. For example, if it is determined that the charge connector of the external charger 72 is connected to the charge inlet 62, it may be determined that there is a charge instruction.

[0048] If it is determined in step S17 that a charge instruction has been issued, the process proceeds to step S18, where the third shutoff switch SW3 is turned on and the first shutoff switch SW1 and the second shutoff switch SW2 are turned off. Thereafter, the process proceeds to step S12, and if the determination in step S12 is affirmative, the processes of steps S15 and S16 are executed. While the second storage battery 22 is charged with power supplied from the charger 61 or the charging inlet 62, voltage equalization control is performed to supply power from the second storage battery 22 to the first storage battery 21. This allows the first storage battery 21 and the second storage battery 22 to be charged even if only the second storage battery 22 is to be charged by external charging equipment out of the first storage battery 21 and the second storage battery 22.

[0049] Most of the charging current supplied from the charging inlet 62 flows to the second storage battery 22, and the charging current supplied from the charging inlet 62 does not flow through the neutral point switch SWm and the negative pole side switch SWn, or almost does not flow through the neutral point switch SWm and the negative pole side switch SWn. This allows the current capacity of the neutral point switch SWm and the negative pole side switch SWn to be reduced. For example, the current capacity of the neutral point switch SWm and the negative pole side switch SWn can be made smaller than the sum of the maximum value of the current flowing through the neutral point path Lm and the negative pole side main path Ln when either the temperature rise control or the voltage equalization control, or both the temperature rise control and the voltage equalization control, is executed and the maximum value of the charging current supplied to the second storage battery 22 from the charger 61 or the charging inlet 62.

[0050] Incidentally, for example, while the vehicle is running, the control amount of the rotating electrical machine 40 may be controlled while the auxiliary machine 60 is driven by power supplied from the second storage battery 22. In this case, a current flowing from the second storage battery 22 to the auxiliary machine 60 and a current flowing for controlling the control amount flow together through the negative main path Ln. However, the above-described arrangement of the negative switch SWn makes it possible to reduce the current capacity of the negative switch SWn.

[0051] <Modification of the first embodiment> The control device 90 may perform the process shown in Fig. 3 instead of the process shown in Fig. 2. In the example shown in Fig. 3, it is assumed that the positive switch SWp and the negative switch SWn are turned on.

[0052] In step S20, it is determined whether or not an instruction to execute at least one of the temperature increase control and the voltage equalization control has been issued.

[0053] If it is determined in step S21 that there is no instruction to execute both the temperature increase control and the voltage equalization control, the process proceeds to step S21, where the neutral point switch SWm is turned off. In this case, the first shutoff switch SW1 is turned on when driving the auxiliary device 60. Furthermore, if it is determined that there is an instruction to charge via the charger 61 or the charging inlet 62, the second shutoff switch SW2 or the third shutoff switch SW3 is turned on.

[0054] On the other hand, if it is determined in step S20 that an instruction to execute at least one of the temperature rise control and the voltage equalization control has been issued, the process proceeds to step S22, where the neutral point switch SWm is turned on. The first to third shutoff switches SW1 to SW3 are turned off. Then, the process proceeds to step S23, where the temperature rise control or the voltage equalization control that has been instructed to be executed is executed. Because the first to third shutoff switches SW1 to SW3 are turned off, surge voltages that occur due to the execution of this control are prevented from being transmitted to the auxiliary equipment 60, the charger 61, and the charging inlet 62. This prevents breakdowns in the auxiliary equipment 60, the charger 61, and the charging inlet 62. Incidentally, in step S22, one or two of the first to third shutoff switches SW1 to SW3 may be turned off.

[0055] Second Embodiment The second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in Fig. 4, the neutral point switch SWm is provided in a portion of the neutral point path Lm closer to the intermediate terminal B than the connection points with the high potential side paths L1p, L2p, and L3p. For convenience, the same reference numerals are used for components shown in the following embodiments to designate components that are the same as or correspond to the components shown in Fig. 1 above. In addition, in the drawings corresponding to the following embodiments, some of the components shown in Fig. 1 above are omitted.

[0056] Among the processes executed by the control device 90 of this embodiment, differences from the processes shown in FIG. 2 will be described.

[0057] In step S11, in addition to the second cutoff switch SW2, the neutral point switch SWm is turned on.

[0058] If the determination in step S12 is affirmative, the process proceeds to step S16, and if the determination in step S12 is negative, the process proceeds to step S14.

[0059] In step S17, in addition to the third cutoff switch SW3, the neutral point switch SWm is turned on.

[0060] According to the present embodiment described above, the current capacity of the negative switch SWn can be reduced.

[0061] Third Embodiment The third embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in Fig. 5, the negative electrode side switch SWn is provided in a portion of the negative electrode side main path Ln closer to the second storage battery 22 than the connection points with the low potential side paths L1n, L2n, and L3n.

[0062] According to the present embodiment described above, the current capacity of the neutral point switch SWm can be reduced.

[0063] <Fourth embodiment> The fourth embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in Fig. 6, the high-potential side paths L1p, L2p, and L3p are connected to the positive main path Lp instead of the neutral point path Lm. Also, the low-potential side paths L1n, L2n, and L3n are connected to the neutral point path Lm instead of the negative main path Ln. In this embodiment, the positive main path Lp corresponds to the "first target path," and the neutral point path Lm corresponds to the "second target path."

[0064] According to the present embodiment described above, the current capacity of the positive switch SWp and the neutral point switch SWm can be reduced.

[0065] Fifth Embodiment The fifth embodiment will be described below with reference to the drawings, focusing on the differences from the fourth embodiment. In this embodiment, as shown in Fig. 7, the neutral point switch SWm is provided in a portion of the neutral point path Lm closer to the intermediate terminal B than the connection points with the low potential side paths L1n, L2n, and L3n.

[0066] The process executed by the control device 90 of this embodiment is the same as the process described in Embodiment 2. In this embodiment, the first storage battery 21 can be charged via the charger 61 or the charging inlet 62.

[0067] According to the present embodiment described above, the current capacity of the positive switch SWp can be reduced.

[0068] Sixth Embodiment The sixth embodiment will be described below with reference to the drawings, focusing on differences from the fourth embodiment. In this embodiment, as shown in Fig. 8, the positive electrode side switch SWp is provided in a portion of the positive electrode side main path Lp closer to the first storage battery 21 than the connection points with the high potential side paths L1p, L2p, and L3p.

[0069] According to the present embodiment described above, the current capacity of the neutral point switch SWm can be reduced.

[0070] Seventh Embodiment The seventh 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. 9, the connection mode of the electrical paths for the paths Lp, Lm, and Ln is significantly changed.

[0071] Instead of the neutral point path Lm, a portion of the positive main path Lp that is closer to the first storage battery 21 than the positive switch SWp is connected to second ends of the first high potential side path L1p and the second high potential side path L2p. When the first shutoff switch SW1 is turned on, power can be supplied to the auxiliary device 60 from the series connection of the first storage battery 21 and the second storage battery 22. When the second shutoff switch SW2 is turned on, the series connection of the first storage battery 21 and the second storage battery 22 is charged by the charger 61. In this embodiment, the positive main path Lp corresponds to the "first target path," and the negative main path Ln corresponds to the "second target path."

[0072] A first end of a high-voltage charging path LcH is connected to the third positive terminal C3p of the charging inlet 62. A second end of the high-voltage charging path LcH is connected to a portion of the positive-side main path Lp that is closer to the first storage battery 21 than the positive-side switch SWp. A high-voltage side switch SWH (corresponding to a "shutoff switch") is provided in the high-voltage charging path LcH. In this embodiment, the high-voltage charging path LcH and the first to third high-potential side paths L1p to L3p correspond to a "first connection path."

[0073] A first end of a low-voltage charging path LcL is connected to a portion of the high-voltage charging path LcH closer to the third positive terminal C3p than the high-voltage side switch SWH. A second end of the low-voltage charging path LcL is connected to a portion of the neutral point path Lm closer to the intermediate terminal B than the neutral point switch SWm. The low-voltage charging path LcL is provided with a low-voltage side switch SWL.

[0074] A charging connector connected to an external charger 72 can be connected to the charging inlet 62. The external charger 72 is either a rapid charger that charges at a first charging voltage (e.g., 400 V) or an ultra-rapid charger that charges at a second charging voltage (e.g., 800 V) that is higher than the first charging voltage. When the control device 90 determines that the external charger 72 is a rapid charger, it turns off the high-voltage side switch SWH and turns on the low-voltage side switch SWL and the third cutoff switch SW3. This allows a charging current to be supplied to the second storage battery 22. On the other hand, when the control device 90 determines that the external charger 72 is an ultra-rapid charger, it turns off the low-voltage side switch SWL and turns on the high-voltage side switch SWH and the third cutoff switch SW3. This allows a charging current to be supplied to the series connection of the first storage battery 21 and the second storage battery 22.

[0075] According to the present embodiment described above, the current capacities of the neutral point switch SWm, the positive side switch SWp, and the negative side switch SWn can be reduced. Incidentally, the process shown in FIG. 2 can be applied to this embodiment. In this case, in step S11, all or some of the switches SW1, SW3, SWH, and SWL may be turned off. Furthermore, in step S18, all or some of the switches SW1, SW2, SWH, and SWL may be turned off. Furthermore, the process shown in FIG. 3 can be applied to this embodiment. In this case, in step S22, some but at least one of the first to third shutoff switches SW1 to SW3 and the high-side switch SWH may be turned off.

[0076] Eighth Embodiment The eighth embodiment will be described below with reference to the drawings, focusing on differences from the seventh embodiment. In this embodiment, as shown in Fig. 10, the positive electrode side switch SWp is provided in a portion of the positive electrode side main path Lp closer to the first storage battery 21 than the connection points with the paths L1p, L2p, and LcH.

[0077] According to the present embodiment described above, the current capacity of the negative switch SWn can be reduced.

[0078] Ninth Embodiment The ninth embodiment will be described below with reference to the drawings, focusing on differences from the seventh embodiment. In this embodiment, as shown in Fig. 11, a positive switch SWp is provided in a portion of the positive main path Lp closer to the first storage battery 21 than the connection points with the paths L1p, L2p, and LcH. Also, a negative switch SWn is provided in a portion of the negative main path Ln closer to the second storage battery 22 than the connection points with the low potential paths L1n, L2n, and L3n.

[0079] According to the present embodiment described above, the current capacity of the neutral point switch SWm can be reduced.

[0080] Tenth Embodiment The tenth embodiment will be described below with reference to the drawings, focusing on differences from the seventh embodiment. In this embodiment, as shown in Fig. 12, a neutral point switch SWm is provided in a portion of the neutral point path Lm closer to the intermediate terminal B than the connection point with the low-voltage charging path LcL. In addition, a negative electrode side switch SWn is provided in a portion of the negative electrode side main path Ln closer to the second storage battery 22 than the connection points with each of the low potential side paths L1n, L2n, L3n.

[0081] According to the present embodiment described above, the current capacity of the positive switch SWp can be reduced.

[0082] <Other embodiments> The above embodiment may be modified as follows.

[0083] 2, either the first shut-off switch SW1 or the third shut-off switch SW3 may be turned off. Also, in step S18, either the first shut-off switch SW1 or the second shut-off switch SW2 may be turned off.

[0084] The first cutoff switch SW1 may be provided only in the first high potential side path L1p out of the first low potential side path L1n and the first high potential side path L1p, or may be provided in both the first high potential side path L1p and the first low potential side path L1n.

[0085] The second cutoff switch SW2 may be provided only in the second high potential side path L2p out of the second low potential side path L2n and the second high potential side path L2p, or may be provided in both the second high potential side path L2p and the second low potential side path L2n.

[0086] The third cutoff switch SW3 may be provided only in the third high potential side path L3p out of the third low potential side path L3n and the third high potential side path L3p, or may be provided in both the third high potential side path L3p and the third low potential side path L3n.

[0087] The switches SWp, SWm, SWn, SW1 to SW3, SWL, and SWH are not limited to relays, and may be, for example, a pair of N-channel MOSFETs with their sources connected together, or an IGBT.

[0088] The upper and lower arm switches constituting the inverter are not limited to IGBTs, but may be, for example, N-channel MOSFETs.

[0089] The rotating electrical machine and inverter may be of a type other than three phases, such as five phases or seven phases.

[0090] The power storage device may be configured, for example, as an electric double layer capacitor instead of a storage battery.

[0091] The mobile body on which the power conversion device is mounted is not limited to a vehicle, but may also be, for example, an aircraft or a ship. For example, if the mobile body is an aircraft, the rotating electric machine mounted on the aircraft serves as the power source for the aircraft's flight, and if the mobile body is a ship, the rotating electric machine mounted on the ship serves as the power source for the ship's navigation. Furthermore, the installation of the power conversion device is not limited to a mobile body. [Explanation of symbols]

[0092] 10...power conversion device, 21, 22...first and second storage batteries, 30...inverter, 40...rotating electric machine, 90...control device, Lp...positive side main path, Ln...negative side main path, Lm...neutral point path, SWp...positive side switch, SWn...negative side switch, SWm...neutral point switch.

Claims

1. an electricity storage device (20) having a first electricity storage unit (21) and a second electricity storage unit (22) connected in series to a negative electrode side of the first electricity storage unit; an inverter (30) having upper and lower arm switches (QUH to QWL); a rotating electric machine (40) having windings (41U to 41W) connected to the inverter; a positive main path (Lp) connecting a high potential side terminal of the upper arm switch and a positive side of the first power storage unit; a negative main path (Ln) connecting a low potential side terminal of the lower arm switch and a negative side of the second power storage unit; a neutral point path (Lm) connecting a battery connection point (B) between the negative electrode side of the first power storage unit and the positive electrode side of the second power storage unit and a neutral point (O) of the winding; Switches (SWp, SWn, SWm) provided in the positive main path, the negative main path, and the neutral path; Electrical devices (60-62) having first connection terminals (C1p, C2p, C3p) and second connection terminals (C1n, C2n, C3n); a first connection path (L1p, L2p, L3p, LcH) connecting a first target path, which is any one of the positive main path, the negative main path, and the neutral point path, to the first connection terminal; a second target path, which is any one of the positive main path, the negative main path, and the neutral point path other than the first target path, and a second connection path (L1n, L2n, L3n) connecting the second connection terminal, A power conversion device (10) using at least one of a configuration in which the first connection path is connected to the storage device side of the switch among the first target paths, and a configuration in which the second connection path is connected to the storage device side of the switch among the second target paths.

2. The first target path is the neutral point path (Lm), The power conversion device according to claim 1 , wherein the second target path is either the positive electrode side main path or the negative electrode side main path.

3. The electrical device has a charging inlet (62) to which a charging connector of an external charging device (72) is connected, the first connection path (L3p) to which the first connection terminal (C3p) of the charging inlet is connected is connected only to the neutral path among the positive main path, the negative main path, and the neutral path; 3. The power conversion device according to claim 2, wherein the second connection path (L3n) to which the second connection terminal (C3n) of the charging inlet is connected is connected only to the second target path among the positive side main path, the negative side main path, and the neutral point path.

4. the first connection path is connected to the first target path on the power storage device side relative to the switch, The power conversion device according to any one of claims 1 to 3, wherein the second connection path is connected to the power storage device side of the switch in the second target path.

5. The power conversion device according to any one of claims 1 to 4, further comprising a cutoff switch (SW1 to SW3, SWH) provided in at least one of the first connection path and the second connection path.

6. The power conversion device according to any one of claims 1 to 5, further comprising a control unit (90) that performs switching control of the upper and lower arm switches to flow current between the first storage unit and the second storage unit via the neutral point path and the neutral point.

7. a control unit (90) that controls switching of the upper and lower arm switches to allow current to flow between the first and second storage units via the neutral point path and the neutral point; a cutoff switch (SW1 to SW3, SWH) provided in at least one of the first connection path and the second connection path, The power conversion device according to any one of claims 1 to 4, wherein the control unit turns off the cutoff switch when the switching control is being performed.

8. the electrical device is a plurality of devices, The power conversion device according to claim 7 , wherein the control unit turns off the cutoff switch corresponding to at least one of the electric devices.

9. The electrical equipment includes: a charging inlet (62) to which a charging connector of an external charging device (72) is connected; a charger (61) to which an external AC power source (71) is connected; and an auxiliary device (60) that is driven by being supplied with power, a cutoff switch (SW1 to SW3, SWH) provided in at least one of the first connection path and the second connection path; When the power storage device is being charged from the charging facility via the charging inlet, turning off at least one of the cutoff switch (SW1) corresponding to the auxiliary machine and the cutoff switch (SW2) corresponding to the charger; 3. The power conversion device according to claim 1, further comprising: a control unit (90) that turns off at least one of the cutoff switch (SW1) corresponding to the auxiliary device and the cutoff switch (SW3, SWH, SWL) corresponding to the charging inlet when the power storage device is being charged from the AC power source via the charger.

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