System, program, and system control method

Abstract

A power converter (110, 210, 310) provided in a system (10) comprises: a primary-side circuit (120); a secondary-side circuit (130) including secondary-side switch units (SW2, SW4, SA, SB, K2, K4, UH1-UH4, T2, T4, DD2, DD4, J2, J4); and an insulated transformer (140). The system comprises opposing switch units (SW1, SW3, SC1-SC3, K1, K3, UL1-UL4, T1, T3, DD1, DD3, J1, J3), high-potential paths (104, 204, 304), intermediate paths (106, 206, 306), and low-potential paths (105, 205, 305).

Description

System, Program, and System Control Method Cross - reference to Related Applications

[0001] This application is based on Japanese Application No. 2024 - 193697 filed on November 5, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a system, a program, and a system control method.

[0003] Conventionally, a power converter connected to a power storage unit is known. The power converter has a primary - side circuit including a primary - side terminal pair and a secondary - side circuit including a secondary - side terminal pair. The primary - side terminal pair is connected in parallel to the power storage unit. The secondary - side terminal pair is connected in series to the power storage unit. As an example of such a technology, the technology disclosed in Patent Document 1 can be cited.

[0004] Japanese Unexamined Patent Application Publication No. 2022 - 23722

[0005] A system including the above - described power converter may be connected to an electrical load. For example, in a system where the low - potential - side terminal of the secondary - side terminal pair and the positive - electrode side of the power storage unit are connected, the electrical load is connected to the high - potential - side terminal of the secondary - side terminal pair, and the electrical load is connected to the negative - electrode side of the power storage unit. In this case, an overcurrent may flow through a path including the power storage unit, the secondary - side circuit, and the electrical load. Therefore, a configuration that can protect the system when an overcurrent flows is desired.

[0006] The present disclosure has been made to solve the above problems, and its main object is to provide a system, a program, and a system control method that can protect the system when an overcurrent flows.

[0007] This disclosure relates to a system comprising a positive electrode connection part connectable to the positive electrode terminal of a power storage unit, a negative electrode connection part connectable to the negative electrode terminal of the power storage unit, and a power converter, wherein the power converter includes a primary circuit including a first high-potential terminal and a first low-potential terminal, a secondary circuit including a second high-potential terminal, a second low-potential terminal, and a secondary switch section, and an isolation transformer connecting the primary circuit and the secondary circuit, wherein the secondary switch section prevents the flow of either the current flowing from the second high-potential terminal to the second low-potential terminal or the current flowing from the second low-potential terminal to the second high-potential terminal when it is turned off, and allows the flow of the other regardless of whether it is turned on or off, the first high-potential terminal is connected to the positive electrode connection part, and the first low-potential terminal is connected to the negative electrode connection part.

[0008] A first aspect of the present disclosure comprises: a high-potential path connecting the second high-potential terminal and an electrical load; an intermediate path connecting the second low-potential terminal and the positive electrode connection; a low-potential path connecting the negative electrode connection and the electrical load; and a counter-switch that, when turned off, prevents the flow of current permitted by the secondary-side switch.

[0009] A second aspect of the present disclosure comprises: a high-potential path connecting the positive electrode connection and an electrical load; an intermediate path connecting the negative electrode connection and the second high-potential terminal; a low-potential path connecting the second low-potential terminal and the electrical load; and a counter-switch that, when turned off, prevents the flow of current permitted by the secondary-side switch.

[0010] In the systems of the first and second embodiments, it is conceivable to use a secondary switch to interrupt overcurrents flowing through the path including the energy storage unit, secondary circuit, and electrical load. Overcurrents can flow in the charging direction of the energy storage unit, from the second high-potential terminal to the second low-potential terminal, and in the discharge direction of the energy storage unit, from the second low-potential terminal to the second high-potential terminal. Here, if the direction of current blocked when the secondary switch is turned off is unidirectional, it may not be possible to block the flow of current flowing in the opposite direction to the direction of current that can be blocked by the secondary switch. In this case, there is a concern that the overcurrent cannot be properly interrupted because it is not possible to interrupt either the overcurrent flowing in the discharge direction or the overcurrent flowing in the charging direction.

[0011] Therefore, in the first and second embodiments of this disclosure, the system includes an opposing switch. When the opposing switch is turned off, it prevents the flow of current permitted by the secondary switch. This makes it possible to interrupt the flow of current from the second high-potential terminal to the second low-potential terminal and the flow of current from the second low-potential terminal to the second high-potential terminal.

[0012] In the first and second embodiments, the secondary side switch unit or the opposing switch unit is turned off. This allows the secondary side switch unit to be used while appropriately interrupting overcurrents flowing through the energy storage unit, secondary side circuit, and the path including the electrical load. As a result, the system can be protected in the event of an overcurrent while the secondary side switch unit is in use.

[0013] The above-mentioned and other purposes, features, and benefits of this disclosure will be further clarified by the following detailed description with reference to the attached drawings. The drawings are as follows: Figure 1 is a system configuration diagram according to the first embodiment; Figure 2 is a power converter configuration diagram; Figure 3 is a flowchart showing the control processing procedure performed by the control device; Figure 4 is a flowchart showing the processing procedure for overcurrent interruption control; Figure 5 is a time chart showing an example of overcurrent interruption control; Figure 6 is a time chart showing the control of a comparative example; Figure 7 is a system configuration diagram according to the second embodiment; Figure 8 is a power converter configuration diagram according to the third embodiment; Figure 9 is a system configuration diagram; Figure 10 is a system configuration diagram according to a modified example of the third embodiment; Figure 11 is a system configuration diagram according to a modified example of the third embodiment; Figure 12 is a system configuration diagram according to a modified example of the third embodiment; Figure 13 is a system configuration diagram according to a modified example of the third embodiment; Figure 14 is a system configuration diagram according to a modified example of the third embodiment; Figure 15 is a system configuration diagram according to the fourth embodiment; Figure 16 is a flowchart showing the processing procedure for overcurrent interruption control; Figure 17 is a system configuration diagram according to a modified example of the fourth embodiment; Figure 1 Figure 8 is a system configuration diagram relating to a modified version of the fourth embodiment, Figure 19 is a system configuration diagram relating to a modified version of the fourth embodiment, Figure 20 is a system configuration diagram relating to the fifth embodiment, Figure 21 is a system configuration diagram relating to a modified version of the fifth embodiment, Figure 22 is a system configuration diagram relating to a modified version of the fifth embodiment, Figure 23 is a system configuration diagram relating to a modified version of the fifth embodiment, Figure 24 is a flowchart showing the charging control processing procedure according to the sixth embodiment, and Figure 25 is a diagram showing a part of the secondary side circuit of the power converter. Figure 26 is a diagram showing an example of charging control, Figure 27 is a flowchart showing the processing procedure of charging control according to a modified example of the sixth embodiment, Figure 28 is a diagram showing an example of charging control, Figure 29 is a diagram showing an example of charging control, Figure 30 is a diagram showing an example of charging control, Figure 31 is a flowchart showing the processing procedure of charging control according to the seventh embodiment, Figure 32 is a diagram showing an example of charging control, Figure 33 is a diagram showing an example of charging control, and Figure 34 is a diagram showing an example of charging control according to a modified example of the seventh embodiment.Figure 35 shows an example of charging control according to a modification of the seventh embodiment; Figure 36 is a configuration diagram of a power converter according to another embodiment; Figure 37 is a configuration diagram of a power converter according to another embodiment; Figure 38 is a configuration diagram of a power converter according to another embodiment; Figure 39 is a configuration diagram of a power converter according to another embodiment; Figure 40 is a configuration diagram of a system according to another embodiment; Figure 41 is a configuration diagram of a system according to another embodiment; and Figure 42 is a configuration diagram of a system according to another embodiment.

[0014] Multiple embodiments will be described with reference to the drawings. In multiple embodiments, functionally and / or structurally corresponding and / or related parts may be given the same reference numeral, or reference numerals that differ by hundreds or more digits. For corresponding and / or related parts, refer to the descriptions of other embodiments.

[0015] <First Embodiment> Hereinafter, a first embodiment of the system relating to this disclosure will be described with reference to the drawings. In this embodiment, the system constitutes a system installed in an electric vehicle such as an electric vehicle or a hybrid vehicle.

[0016] As shown in Figure 1, the system 10 comprises a plurality of modules 100, 200, and 300. In this embodiment, the system 10 comprises three modules, specifically a first module 100, a second module 200, and a third module 300. The first, second, and third modules 100, 200, and 300 each include positive electrode connection parts 101, 201, and 301 that can be connected to the positive terminals of the storage batteries (corresponding to the "energy storage units") 103, 203, and 303, and negative electrode connection parts 102, 202, and 302 that can be connected to the negative terminals of the storage batteries 103, 203, and 303. In each module 100, 200, and 300, the positive terminal connection sections 101, 201, and 301 are connected to the positive terminals of the storage batteries 103, 203, and 303, and the negative terminal connection sections 102, 202, and 302 are connected to the negative terminals of the storage batteries 103, 203, and 303.

[0017] The storage batteries 103, 203, and 303 are, for example, secondary batteries such as lithium-ion batteries or nickel-metal hydride batteries. In this embodiment, the rated voltage of the storage batteries 103, 203, and 303 is the same value (for example, 400V).

[0018] System 10 comprises a main high-potential path 20, a main low-potential path 21, a smoothing capacitor 22, and an electrical load 23. The electrical load 23 is connected to the main high-potential path 20 and the main low-potential path 21. The smoothing capacitor 22 is also connected to the main high-potential path 20 and the main low-potential path 21. The smoothing capacitor 22 is connected in parallel to the electrical load 23.

[0019] The positive terminals of each module 100, 200, and 300 are connected to the main high-potential path 20, and the negative terminals of each module 100, 200, and 300 are connected to the main low-potential path 21. As a result, each module 100, 200, and 300 are connected in parallel to the electrical load 23.

[0020] Specifically, the electrical load 23 comprises an inverter 23a and a rotating electric machine 23b. The inverter 23a has three series connections of upper arm switches and lower arm switches. Semiconductor switching elements such as IGBTs and N-channel MOSFETs can be used as the upper arm switches and lower arm switches. The rotating electric machine 23b has armature windings for each phase that are connected to the upper arm switches and lower arm switches. The inverter 23a controls the current flowing through the armature windings of each phase. The rotating electric machine 23b is a vehicle-mounted main machine, and the rotor of the rotating electric machine 23b is capable of transmitting power to the vehicle's drive wheels. The rotating electric machine 23b is, for example, a permanent magnet synchronous machine.

[0021] The positive terminal of inverter 23a is connected to the main high-potential path 20, and the negative terminal of inverter 23a is connected to the main low-potential path 21. Inverter 23a converts DC power supplied from system 10 into AC power and supplies the converted AC power to each phase winding of the rotating electric machine 23b. In this case, the rotating electric machine 23b becomes the power source for the vehicle's movement. The rotating electric machine 23b also performs regenerative power generation using the rotational force applied to the rotor. In this case, inverter 23a converts the generated AC power into DC power and outputs the converted DC power to modules 100, 200, and 300.

[0022] Each module 100, 200, and 300 is equipped with a power converter 110, 210, and 310. Hereinafter, the battery 103 and power converter 110 connected to the first module 100 will be referred to as the "first battery 103" and the "first power converter 110," the battery 203 and power converter 210 connected to the second module 200 will be referred to as the "second battery 203" and the "second power converter 210," and the battery 303 and power converter 310 connected to the third module 300 will be referred to as the "third battery 303" and the "third power converter 310."

[0023] The connection relationship between the battery and the power converter in each module 100, 200, and 300 will be explained in detail. The configurations of each module 100, 200, and 300 are basically the same. Therefore, the following explanation will focus on the first module 100.

[0024] Figure 2 shows an example of the first power converter 110. The first power converter 110 is a center-tapped, isolated DC-DC converter. The first power converter 110 comprises a primary circuit 120 and a secondary circuit 130. As shown in Figures 1 and 2, the primary circuit 120 has a first high-potential terminal 111H and a first low-potential terminal 111L. The secondary circuit 130 has a second high-potential terminal 112H and a second low-potential terminal 112L.

[0025] Returning to the explanation of Figure 1, the first module 100 includes a first high-potential path 104, a first low-potential path 105, and a first intermediate path 106. The first high-potential path 104 connects the main high-potential path 20 and the second high-potential side terminal 112H. That is, the second high-potential side terminal 112H is connected to the electrical load 23 via the first high-potential path 104 and the main high-potential path 20. The first low-potential path 105 connects the negative electrode connection part 102 and the main low-potential path 21. That is, the negative electrode connection part 102 is connected to the electrical load 23 via the first low-potential path 105 and the main low-potential path 21. The first intermediate path 106 connects the second low-potential side terminal 112L and the positive electrode connection part 101. In other words, the secondary circuit 130 of the first power converter 110 is connected in series with the first battery 103 on the positive electrode side of the first battery 103.

[0026] The primary circuit 120 of the first power converter 110 is connected in parallel to the first storage battery 103. In Figure 1, the first high-potential terminal 111H is connected to an intermediate portion of the first intermediate path 106. The first high-potential terminal 111H is connected to the positive electrode connection 101 via a portion of the first intermediate path 106. The first low-potential terminal 111L is connected to an intermediate portion of the first low-potential path 105. The first low-potential terminal 111L is connected to the negative electrode connection 102 via a portion of the first low-potential path 105.

[0027] As shown in Figure 2, the primary circuit 120 includes first and second upper arm switches S1H and S2H, and first and second lower arm switches S1L and S2L as primary switches. In this embodiment, the first and second upper arm switches S1H and S2H and the first and second lower arm switches S1L and S2L are semiconductor switching elements, more specifically N-channel MOSFETs. Each switch S1H, S2H, S1L, and S2L has a body diode D1H, D2H, D1L, and D2L. Note that each switch S1H, S2H, S1L, and S2L may be, for example, an N-channel IGBT. In this case, a freewheeling diode is connected in antiparallel to each switch S1H, S2H, S1L, and S2L.

[0028] The drains of the first upper arm switch S1H and the second upper arm switch S2H are connected to the first high-potential terminal 111H. The source of the first upper arm switch S1H is connected to the drain of the first lower arm switch S1L. The source of the second upper arm switch S2H is connected to the drain of the second lower arm switch S2L. The source of the first lower arm switch S1L and the source of the second lower arm switch S2L are connected to the first low-potential terminal 111L.

[0029] The secondary circuit 130 comprises first to fourth switches SW1 to SW4 and a reactor 132. In this embodiment, the first to fourth switches SW1 to SW4 are semiconductor switching elements, more specifically N-channel MOSFETs. Each of the switches SW1 to SW4 also has body diodes D1 to D4.

[0030] The first power converter 110 includes an isolation transformer 140 that connects the primary circuit 120 and the secondary circuit 130. The isolation transformer 140 includes a primary coil 141 and a secondary coil 142 having a center tap 143. The first end of the primary coil 141 is connected to the connection point between the first upper arm switch S1H and the first lower arm switch S1L. The second end of the primary coil 141 is connected to the connection point between the second upper arm switch S2H and the second lower arm switch S2L.

[0031] The first end of the secondary coil 142 is connected to the first end of the reactor 132 via the first switch SW1 and the second switch SW2. The second end of the secondary coil 142 is connected to the first end of the reactor 132 via the third switch SW3 and the fourth switch SW4. The second end of the reactor 132 is connected to the second high-potential terminal 112H. The center tap 143 of the secondary coil 142 is connected to the second low-potential terminal 112L. Details of the connections between each switch SW1 to SW4 in the secondary circuit 130 will be described later.

[0032] The primary circuit 120 includes a first capacitor 121. The first capacitor 121 connects a first high-potential terminal 111H and a first low-potential terminal 111L. The secondary circuit 130 includes a second capacitor 131. The second capacitor 131 connects a second high-potential terminal 112H and a second low-potential terminal 112L.

[0033] As shown in Figure 1, the second power converter 210 includes a first high-potential terminal 211H, a first low-potential terminal 211L, a second high-potential terminal 212H, and a second low-potential terminal 212L. The third power converter 310 includes a first high-potential terminal 311H, a first low-potential terminal 311L, a second high-potential terminal 312H, and a second low-potential terminal 312L.

[0034] The second module 200 includes a second high-potential path 204, a second low-potential path 205, and a second intermediate path 206. The third module 300 includes a third high-potential path 304, a third low-potential path 305, and a third intermediate path 306. In the second and third modules 200 and 300, the connection relationships between the terminals 211H, 211L, 212H, 212L, 311H, 311L, 312H, and 312L of the power converters 210 and 310 and the storage batteries 203 and 303 are the same as in the first module 100. Therefore, a detailed explanation of the connection relationships is omitted.

[0035] The main high-potential path 20 connects the first, second, and third high-potential paths 104, 204, and 304. The main low-potential path 21 connects the first, second, and third low-potential paths 105, 205, and 305.

[0036] The second power converter 210 and the third power converter 310 are center-tapped, isolated DC-DC converters, similar to the first power converter 110, and include a primary circuit, a secondary circuit, and an isolated transformer. In the second power converter 210, the primary circuit includes a first high-potential terminal 211H and a first low-potential terminal 211L, and the secondary circuit includes a second high-potential terminal 212H and a second low-potential terminal 212L. In the third power converter 310, the primary circuit includes a first high-potential terminal 311H and a first low-potential terminal 311L, and the secondary circuit includes a second high-potential terminal 312H and a second low-potential terminal 312L. The primary circuits of the second and third power converters 210 and 310 are similar to those of the first power converter 110, and include first and second upper arm switches S1H and S2H, and first and second lower arm switches S1L and S2L. The secondary circuits of the second and third power converters 210 and 310 are equipped with first to fourth switches SW1 to SW4, similar to the first power converter 110.

[0037] In this embodiment, the configurations of the second power converter 210 and the third power converter 310 are basically the same as those of the first power converter 110, so a detailed description of the second power converter 210 and the third power converter 310 is omitted. Each of the power converters 110, 210, and 310 is also referred to as a partial power converter (PPC).

[0038] The first module 100 includes a drive circuit 160. The drive circuit 160 drives the first and second upper arm switches S1H and S2H, the first and second lower arm switches S1L and S2L, and the first to fourth switches SW1 to SW4 of the first power converter 110 to turn on and off. Specifically, the first drive circuit 160 charges and discharges the gates of each switch S1H, S2H, S1L, S2L, and SW1 to SW4. The first drive circuit 160 is controlled by a control device 170 provided in the system 10.

[0039] Furthermore, the second and third modules 200 and 300, like the first module 100, are equipped with drive circuits 260 and 360. Since the configuration of the drive circuits 260 and 360 of the second and third modules 200 and 300 is basically the same as the configuration of the drive circuit 160 of the first module 100, a detailed explanation of the drive circuits 260 and 360 will be omitted.

[0040] Each module 100, 200, and 300 is equipped with switch switching units 180, 280, and 380, respectively. Hereinafter, the switch switching unit 180 of the first module 100 will be referred to as the "first switch switching unit 180," the switch switching unit 280 of the second module 200 will be referred to as the "second switch switching unit 280," and the switch switching unit 380 of the third module 300 will be referred to as the "third switch switching unit 380."

[0041] The first switch switching unit 180 includes a precharge switch 181, a precharge resistor 182, and a positive-side switch 183. In this embodiment, the precharge switch 181 and the positive-side switch 183 are relays (specifically, mechanical relays). The precharge switch 181 and the precharge resistor 182 are connected in series. The positive-side switch 183 is connected in parallel to the series connection of the precharge switch 181 and the precharge resistor 182.

[0042] The first switch switching unit 180 is located in the portion of the first intermediate path 106 that is closer to the positive electrode connection portion 101 than the portion that connects to the first high-potential side terminal 111H. In other words, the first switch switching unit 180 is located on a path common to both the current flow path when current flows from the first storage battery 103 to the first high-potential side terminal 111H and the current flow path when current flows from the first storage battery 103 to the second low-potential side terminal 112L.

[0043] The second switch switching unit 280, like the first switch switching unit 180, includes a precharge switch 281, a precharge resistor 282, and a positive-side switch 283. The third switch switching unit 380, like the first switch switching unit 180, includes a precharge switch 381, a precharge resistor 382, ​​and a positive-side switch 383.

[0044] Each of the modules 100, 200, and 300 includes a negative-side switch 184, 284, 384. In each of the modules 100, 200, and 300, the negative-side switches 184, 284, 384 are provided at a portion closer to the negative connection portions 102, 202, 302 than the connection portions with the first low-potential-side terminals 111L, 211L, 311L in the low-potential paths 105, 205, 305. In the present embodiment, the negative-side switches 184, 284, 384 are relays (specifically, mechanical relays).

[0045] The system 10 includes a main voltage sensor 30 and a main current sensor 31. The main voltage sensor 30 detects a system voltage, which is the voltage between the main high-potential path 20 and the main low-potential path 21. The main current sensor 31 detects the current flowing through the electrical load 23. In the example shown in FIG. 1, the main current sensor 31 detects the current flowing through a portion of the main low-potential path 21 on the electrical load 23 side rather than the connection point with the first low-potential-side terminals 111L, 211L, 311L. Detection values of each of the sensors 30, 31 are input to the control device 170. Note that the main current sensor 31 may detect the current flowing through a portion of the main high-potential path 20 on the electrical load 23 side rather than the connection point with the second high-potential-side terminals 112H, 212H, 312H.

[0046] Each of the modules 100, 200, and 300 includes individual voltage sensors 155, 255, 355. The individual voltage sensors 155, 255, 355 are provided corresponding to the storage batteries 103, 203, 303 and detect the voltages of the storage batteries 103, 203, 303. Detection values of each of the individual voltage sensors 155, 255, 355 are input to the control device 170.

[0047] Each module 100, 200, 300 includes individual current sensors 150, 250, 350. The individual current sensors 150, 250, 350 are provided corresponding to the storage batteries 103, 203, 303, and detect the current flowing through the storage batteries 103, 203, 303. In the present embodiment, the sign of the detection value of each individual current sensor 150, 250, 350 is positive when the discharge current of the storage battery 103, 203, 303 flows in a certain direction, and negative when the charge current of the storage battery 103, 203, 303 flows. The detection values of each individual current sensor 150, 250, 350 are input to the control device 170.

[0048] Each power converter 110, 210, 310 includes a first voltage sensor and a second voltage sensor, and a first current sensor and a second current sensor. Taking the first power converter 110 as an example, as shown in FIG. 2, the first voltage sensor 151 detects the primary-side voltage, which is the voltage between the first high-potential-side terminal 111H and the first low-potential-side terminal 111L. The second voltage sensor 154 detects the secondary-side voltage, which is the voltage between the second high-potential-side terminal 112H and the second low-potential-side terminal 112L.

[0049] The first current sensor 152 detects the primary-side current flowing through the primary-side circuit 120. The second current sensor 153 detects the secondary-side current flowing through the secondary-side circuit 130 (for example, the reactor 132). In the present embodiment, the sign of the detection value of the second current sensor 153 is positive when the current flows from the first end to the second end of the reactor 132, and negative when the current flows from the second end to the first end of the reactor 132. The detection values of the first and second voltage sensors and the first and second current sensors included in each power converter 110, 210, 310 are input to the control device 170.

[0050] As shown in FIG. 1, the control device 170 is an electronic control unit (ECU: Electronic Control Unit) that performs various controls of the system 10, and includes a processor 171 as hardware, a storage unit 172, and a communication bus 173 that connects the processor 171 and the storage unit 172.

[0051] The memory unit 172 includes memory and storage as hardware. The memory is a storage device for storing data used for processing by the control device 170. The memory provides the processor 171 with a temporary workspace for use when the processor 171 performs processing. The memory includes, for example, ROM or RAM. The storage is a storage device that stores various programs and data for the processor 171 to read and execute, and is a non-transitory tangible storage medium. The storage includes, for example, an HDD or flash memory. The storage stores program information and the like for processing as shown in Figures 3, 4, 16, 24, 27, and 31, which will be described later.

[0052] For example, program information stored on a non-transitional physical recording medium is installed in the storage unit 172. The recording medium is, for example, a USB memory stick, a CD-ROM, or a DVD. Also, for example, program information transmitted via a communication network, such as OTA (Over The Air), is installed in the storage unit 172.

[0053] Next, we will explain the control performed by the control device 170.

[0054] The control device 170 controls the precharge switches 181, 281, 381, the positive side switches 183, 283, 383, and the negative side switches 184, 284, 384. For example, when the control device 170 precharges each capacitor 22, 121, 131 when the system 10 is started, it turns off the positive side switches 183, 283, 383 and turns on the precharge switches 181, 281, 381 and the negative side switches 184, 284, 384. When the control device 170 controls the switching of each power converter 110, 210, 310, it turns on the positive side switches 183, 283, 383 and the negative side switches 184, 284, 384 and turns off the precharge switches 181, 281, 381.

[0055] The control device 170 controls the switching of each power converter 110, 210, and 310 based on request information for the system 10. The request information is input from a higher-level control device (not shown). For example, the request information includes the requested power to be supplied from the system 10 to the electrical load 23, or the requested power to be regenerated from the electrical load 23 to the system 10. In this case, the detected values ​​of each sensor 30, 31, 150-154, 155, 250, 255, 350, and 355 may be used to control the switching of each power converter 110, 210, and 310 to satisfy the requested values.

[0056] Figure 3 shows the control processing procedure performed by the processor 171 of the control device 170. This control is performed after the system 10 is started and the pre-charging of each capacitor 22, 121, and 131 is completed.

[0057] In step S10, request information is acquired. In step S11, switching control of each power converter 110, 210, and 310 is performed based on the acquired request information.

[0058] In step S12, overcurrent protection control is performed. Overcurrent protection control will be described later.

[0059] In step S13, it is determined whether or not to terminate the operation of system 10. For example, if the vehicle's start switch is turned off, it is determined that the operation of system 10 will terminate. The start switch is, for example, an ignition switch or a push-button start switch, and is operated by the vehicle user. If the determination in step S13 is positive, this control is terminated. On the other hand, if the determination in step S13 is negative, the process in step S10 is performed again.

[0060] The following section describes overcurrent interruption control.

[0061] Overcurrent interruption control is a control in each module 100, 200, 300 to interrupt overcurrents flowing through the paths including the batteries 103, 203, 303, the secondary circuits of the power converters 110, 210, 310, and the electrical load 23. For example, focusing on the first module 100, the paths including the first battery 103, the secondary circuit 130 of the first power converter 110, and the electrical load 23 are the main high-potential path 20, the main low-potential path 21, the first high-potential path 104, the first low-potential path 105, and the first intermediate path 106. Current flows through these paths in the discharge direction of the first battery 103 and in the charging direction of the first battery 103. When current flows in the discharge direction of the first battery 103, the current flows from the second low-potential terminal 112L to the second high-potential terminal 112H. When current flows in the charging direction of the first battery 103, the current flows from the second high-potential terminal 112H to the second low-potential terminal 112L.

[0062] For example, if a short-circuit abnormality occurs in which the upper arm switch and lower arm switch of the inverter 23a are turned on simultaneously, an overcurrent may flow in the discharge direction of each battery 103, 203, and 303. Also, for example, if the regenerative power from the rotating electric machine 23b is excessively large, an overcurrent may flow in the charging direction of each battery 103, 203, and 303.

[0063] In this embodiment, overcurrent interruption control is performed using the first to fourth switches SW1 to SW4 located in the secondary circuits of each power converter 110, 210, and 310. Here, by turning off the first to fourth switches SW1 to SW4, it is possible to prevent the flow of current in the reverse direction through the corresponding body diodes. On the other hand, regardless of whether the first to fourth switches SW1 to SW4 are on or off, the flow of current in the forward direction through the body diodes corresponding to the first to fourth switches SW1 to SW4 is permitted. In this case, there is a concern that the overcurrent cannot be properly interrupted because it is not possible to interrupt either the overcurrent flowing in the discharge direction or the overcurrent flowing in the charge direction.

[0064] Therefore, in the secondary circuits of each power converter 110, 210, and 310, the first and second switches SW1 and SW2 are connected in series such that when they are turned off, the direction of current flow blocked is in opposite directions. Also, the third and fourth switches SW3 and SW4 are connected in series such that when they are turned off, the direction of current flow blocked is in opposite directions.

[0065] Using the first power converter 110 as an example, as shown in Figure 2 above, the drain of the first switch SW1 is connected to the first end of the secondary coil 142. The source of the first switch SW1 is connected to the source of the second switch SW2. The drain of the third switch SW3 is connected to the second end of the secondary coil 142. The source of the third switch SW3 is connected to the source of the fourth switch SW4. The drains of the second switch SW2 and the fourth switch SW4 are connected to the first end of the reactor 132. In this embodiment, the second and fourth switches SW2 and SW4 correspond to the "secondary switch section," and the first and third switches SW1 and SW3 correspond to the "opposing switch section."

[0066] When the first switch SW1 is turned off, the flow of current permitted by the second switch SW2 is blocked. Similarly, when the second switch SW2 is turned off, the flow of current permitted by the first switch SW1 is blocked. The currents that the third and fourth switches SW3 and SW4 can block are the same as those described for the first and second switches SW1 and SW2. This makes it possible to interrupt the flow of current from the second high-potential terminal 112H to the second low-potential terminal 112L and from the second low-potential terminal 112L to the second high-potential terminal 112H in the secondary circuit 130. Therefore, by utilizing the first to fourth switches SW1 to SW4, it is possible to appropriately interrupt overcurrents flowing through the path including the first battery 103, the secondary circuit 130 of the first power converter 110, and the electrical load 23.

[0067] The control device 170 performs a determination process and a switch control process in overcurrent interruption control. The determination process determines whether or not an overcurrent is flowing through the path including the first battery 103, the secondary circuit 130 of the first power converter 110, and the electrical load 23. The switch control process, when the determination process determines that an overcurrent is flowing, turns off a switch among the first to fourth switches SW1 to SW4 that can block the flow of the overcurrent. By performing overcurrent interruption control, the system 10 can be protected when an overcurrent flows while utilizing the first to fourth switches SW1 to SW4.

[0068] The following section provides a detailed explanation of overcurrent protection control.

[0069] In this embodiment, the control device 170 performs a determination process to determine whether or not an overcurrent is flowing based on the current Ib flowing through the storage batteries 103, 203, and 303. The control device 170 performs the determination process and the switch control process individually for each module 100, 200, and 300. The determination process and the switch control process will be explained below using the first module 100 as an example.

[0070] The control device 170 performs a determination process to determine whether the magnitude of the current Ib1 flowing through the first battery 103 exceeds a predetermined discharge value Ida or a predetermined charge value Ica. The predetermined discharge value Ida and predetermined charge value Ica are positive values, and are, for example, the upper limit of the current that can flow through the first battery 103 or a value lower than the upper limit. For example, the predetermined discharge value Ida and predetermined charge value Ica are determined based on the rated capacity of the first battery 103. The current Ib1 flowing through the first battery 103 can be the detected value of an individual current sensor 150 provided in conjunction with the first battery 103.

[0071] Specifically, the control device 170 determines that an overcurrent is flowing in the discharge direction of the first battery 103 when it determines that the current Ib1 flowing through the first battery 103 exceeds a predetermined discharge value Ida. The control device 170 also determines that an overcurrent is flowing in the charge direction of the first battery 103 when it determines that the current Ib1 flowing through the first battery 103 falls below a predetermined charge value "-Ica". This enables the implementation of overcurrent interruption control suitable for protecting the first battery 103 when an overcurrent flows.

[0072] If the control device 170 determines that an overcurrent is flowing in the discharge direction of the first battery 103 as part of its switch control processing, it turns off the first and third switches SW1 and SW3. This interrupts the current flowing in the discharge direction of the first battery 103. Also, if the control device 170 determines that an overcurrent is flowing in the charge direction of the first battery 103 as part of its switch control processing, it turns off the second and fourth switches SW2 and SW4. This interrupts the current flowing in the charge direction of the first battery 103.

[0073] Figure 4 shows the processing procedure for overcurrent protection control. Overcurrent protection control is the process in step S12 of Figure 3.

[0074] In step S20, the current Ib1 flowing through the first battery 103 is obtained. In step S21, it is determined whether the obtained current Ib1 exceeds the predetermined discharge value Ida. If the determination in step S21 is negative, the process proceeds to step S22. In step S22, it is determined whether the obtained current Ib1 is below the predetermined charge value "-Ica". If the determination in step S22 is negative, the process proceeds to step S23. In step S23, it is determined that no overcurrent is flowing through the path including the first battery 103, the secondary circuit 130 of the first power converter 110, and the electrical load 23, and the process proceeds to step S13 shown in Figure 3.

[0075] If a positive determination is made in step S21, it is determined that an overcurrent is flowing in the discharge direction of the first battery 103 in the path including the first battery 103, the secondary circuit 130 of the first power converter 110, and the electrical load 23, and the process proceeds to step S24. In step S24, the second-side circuit 130 of the first power converter 110 is controlled, and the first switch SW1 and the third switch SW3 are turned off. This allows for accurate interruption of the overcurrent flowing in the discharge direction of the first battery 103.

[0076] If a positive determination is made in step S22, it is determined that an overcurrent is flowing in the charging direction of the first battery 103 in the path including the first battery 103, the secondary circuit 130 of the first power converter 110, and the electrical load 23, and the process proceeds to step S25. In step S25, the second switch SW2 and the fourth switch SW4 are turned off, with the secondary circuit 130 of the first power converter 110 as the control target. This allows for accurate interruption of the overcurrent flowing in the charging direction of the first battery 103. Note that the processing in steps S20 to S22 corresponds to the "determination process," and the processing in steps S24 and S25 corresponds to the "switch control process."

[0077] Figure 5 shows an example of overcurrent interruption control for the first module 100. In Figure 5, (a) shows the change in voltage Vdc of the electrical load 23, (b) shows the change in current Ib1 flowing through the first battery 103, (c) shows the determination result of the determination process, and (d) shows the on / off state of the first and third switches SW1 and SW3. The voltage Vdc of the electrical load 23 is, for example, the voltage of the smoothing capacitor 22.

[0078] During the period from after the pre-charging of each capacitor 22, 121, and 131 is completed until time t1, the control device 170 performs switching control of each power converter 110, 210, and 310 based on the requested information.

[0079] Here, the operating modes during switching control of each power converter 110, 210, and 310 will be described. In this embodiment, the secondary circuit of each power converter 110, 210, and 310 is equipped with first to fourth switches SW1 to SW4 as bidirectional switches. In this configuration, it is possible to operate each power converter 110, 210, and 310 by selecting either a positive voltage mode or a negative voltage mode. The positive voltage mode is a mode in which each power converter 110, 210, and 310 is operated so as to increase the voltage at the second high-potential terminals 112H, 212H, and 312H relative to the second low-potential terminals 112L, 212L, and 312L. The negative voltage mode is a mode in which each power converter 110, 210, and 310 is operated so as to lower the voltage at the second high-potential terminals 112H, 212H, and 312H relative to the second low-potential terminals 112L, 212L, and 312L. Based on the acquired request information, the control device 170 selects the operating mode of each power converter 110, 210, and 310 to either the positive voltage mode or the negative voltage mode.

[0080] When the control device 170 operates each power converter 110, 210, and 310 in positive voltage mode, it fixes the first and third switches SW1 and SW3 of the secondary circuit to ON and controls the switching between the switches S1H, S2H, S1L, and S2L of the primary circuit and the second and fourth switches SW2 and SW4 of the secondary circuit. When the control device 170 operates each power converter 110, 210, and 310 in negative voltage mode, it fixes the second and fourth switches SW2 and SW4 of the secondary circuit to ON and controls the switching between the switches S1H, S2H, S1L, and S2L of the primary circuit and the first and third switches SW1 and SW3 of the secondary circuit.

[0081] In this embodiment, the first to fourth switches SW1 to SW4 of the secondary circuit of each power converter 110, 210, and 310 are used as switches to interrupt overcurrent. This makes it possible to protect the system 10 in the event of an overcurrent while miniaturizing the system 10.

[0082] For example, if a switch for interrupting overcurrent is provided in a location outside the secondary circuit, such as an intermediate path 106, 206, or 306, it may become necessary to add a cooling component for the switch. In this case, in a configuration where the first to fourth switches SW1 to SW4 are provided in the secondary circuit, existing cooling components used to cool each power converter 110, 210, and 310 can be used to cool the first to fourth switches SW1 to SW4. This avoids the need to add cooling components to the system 10. Therefore, the system 10 can be miniaturized while still being protected in the event of an overcurrent.

[0083] Furthermore, for example, in each power converter 110, 210, and 310, compared to a configuration in which the power converter operates in only one of the positive voltage mode or negative voltage mode, the voltage range that can be output from the second high-potential terminals 112H, 212H, 312H and the second low-potential terminals 112L, 212L, 312L can be expanded. This makes it possible to realize a configuration suitable for reducing the capacity of each power converter 110, 210, and 310, and thus protect the system 10 in the event of an overcurrent while miniaturizing the system 10.

[0084] In Figure 5, prior to time t1, the control device 170 operates the first power converter 110 in positive voltage mode. Therefore, the first and third switches SW1 and SW3 are fixed in the ON position. The control device 170 determines that the current Ib1 flowing through the first storage battery 103 during discharge is less than or equal to the predetermined discharge value Ida, and determines that no overcurrent is flowing.

[0085] At time t1, an abnormality occurs in the electrical load 23 (specifically, a short circuit in the inverter 23a), and the voltage Vdc of the electrical load 23 and the voltage of the second capacitor 131 begin to decrease. In Figure 5, after time t1, the voltage Vdc of the electrical load 23 drops to 0 [V]. Due to the abnormality in the electrical load 23, the current Ib1 flowing through the first battery 103 increases in the positive direction, and the current Ib1 flowing through the first battery 103 reaches the predetermined discharge value Ida. In this case, the control device 170 determines that an overcurrent is flowing through the first battery 103 in the discharge direction and switches the first and third switches SW1 and SW3 from on to off. This interrupts the overcurrent flowing through the first battery 103 in the discharge direction.

[0086] Figure 6 shows a comparative example of overcurrent interruption control for the first module 100. In the comparative example, a mechanical relay provided in the first high-potential path 104, the first low-potential path 105, or the first intermediate path 106 is used as a switch to interrupt the overcurrent. In Figure 6, (a) to (c) correspond to Figures 5(a) to (c). Figure 6(d) shows the on / off state of the mechanical relay.

[0087] In mechanical relays, the time it takes to switch from on to off may be longer compared to semiconductor switching elements. Therefore, as shown in Figure 6, during the period from when it is determined that an overcurrent is flowing in the discharge direction of the first battery 103 until the mechanical relay is turned off, the current Ib1 flowing through the first battery 103 may increase excessively beyond the predetermined discharge value Ida. In this case, there is a concern that the reliability of each battery 103, 203, 303 and components such as wiring and relays in each module 100, 200, 300 may decrease due to the occurrence of overcurrent.

[0088] In contrast, in this embodiment, semiconductor switching elements are used as the first to fourth switches SW1 to SW4. This makes it possible to shorten the period from when it is determined that an overcurrent is flowing in the discharge direction of the first battery 103 until the first and third switches SW1 and SW3 are turned off, compared to mechanical relays. Therefore, the system 10 can be protected effectively.

[0089] The control device 170 performs overcurrent interruption control on the second and third modules 200 and 300, similar to the case of the first module 100. As a determination process for the second and third modules 200 and 300, the control device 170 performs a process to determine whether the magnitude of the currents Ib2 and Ib3 flowing through the second and third batteries 203 and 303 exceeds a predetermined discharge value Ida or a predetermined charge value Ica. The currents Ib2 and Ib3 flowing through the second and third batteries 203 and 303 can be determined by the detected values ​​of individual current sensors 250 and 350 provided in correspondence with the second and third batteries 203 and 303. The control device 170 controls the first to fourth switches SW1 to SW4 of the second and third power converters 210 and 310 and performs switch control processing on the second and third modules 200 and 300.

[0090] In this embodiment, the system 10 comprises first to third modules 100, 200, and 300. In this case, current flows not only through the battery 103, 203, and 303, the secondary circuits of each power converter 110, 210, and 310, and the electrical load 23, but also between each module 100, 200, and 300. In this case, if an abnormality occurs in any of the modules 100, 200, and 300, an overcurrent may flow in the other modules in the discharge or charge direction of the battery 103, 203, and 303. Therefore, there is a significant advantage to implementing overcurrent protection control for the system 10.

[0091] The overcurrent interruption control determination process and switch control process are performed individually for each module 100, 200, and 300. In this case, even if overcurrent interruption occurs in any of the modules 100, 200, and 300, the remaining normal modules can continue to operate the power converter. Therefore, in a system 10 equipped with multiple modules 100, 200, and 300, it is possible to realize overcurrent interruption control that is suitable for continuing the operation of the power converters 110, 210, and 310 as much as possible.

[0092] <Modification of the First Embodiment> In step S20 of Figure 4, the current flowing through the secondary circuits of the power converters 110, 210, and 310 may be obtained. The detected value of the second current sensor 153 can be used as the current flowing through the secondary circuits of the power converters 110, 210, and 310. The determination processes in steps S21 and S22 may be executed based on the current flowing through the secondary circuits obtained by the process in step S20. The predetermined discharge value Ida and the predetermined charge value Ica may be, for example, the upper limit of the current that can flow through the secondary circuit 130 or a value lower than the upper limit. In this embodiment, in the event of an overcurrent, overcurrent interruption control suitable for protecting the secondary circuit 130 can be implemented.

[0093] - The determination process for overcurrent interruption control and the switch control process do not necessarily have to be performed individually for each module 100, 200, and 300. For example, in step S20 of Figure 4, the current flowing through the electrical load 23 may be obtained instead of the current Ib flowing through the storage batteries 103, 203, and 303. The value detected by the main current sensor 31 can be used as the current flowing through the electrical load 23. The determination processes in steps S21 and S22 may be executed based on the current flowing through the electrical load 23 obtained by the process in step S20.

[0094] <Second Embodiment> The second embodiment will now be described, focusing on the differences from the first embodiment, with reference to the drawings. In this embodiment, the configuration of each module 100, 200, and 300 has been changed, as shown in Figure 7. First, the configuration of the first module 100 will be described.

[0095] The first module 100 includes a first high-potential path 107, a first low-potential path 108, and a first intermediate path 109. The first high-potential path 107 connects the positive electrode connection 101 and the main high-potential path 20. That is, the positive electrode connection 101 is connected to the electrical load 23 via the first high-potential path 107 and the main high-potential path 20. The first low-potential path 108 connects the second low-potential side terminal 112L and the main low-potential path 21. That is, the second low-potential side terminal 112L is connected to the electrical load 23 via the first low-potential path 108 and the main low-potential path 21. The first intermediate path 109 connects the negative electrode connection 102 and the second high-potential side terminal 112H. In other words, the secondary circuit 130 of the first power converter 110 is connected in series with the first battery 103 on the negative electrode side of the first battery 103.

[0096] The primary circuit 120 of the first power converter 110 is connected in parallel to the first storage battery 103. In Figure 7, the first high-potential terminal 111H is connected to an intermediate portion of the first high-potential path 107. The first high-potential terminal 111H is connected to the positive electrode connection 101 via a portion of the first high-potential path 107. The first low-potential terminal 111L is connected to an intermediate portion of the first intermediate path 109. The first low-potential terminal 111L is connected to the negative electrode connection 102 via a portion of the first intermediate path 109.

[0097] The second module 200 includes a second high-potential path 207, a second low-potential path 208, and a second intermediate path 209. The third module 300 includes a third high-potential path 307, a third low-potential path 308, and a second intermediate path 309. In the second module 200 and the third module 300, the connection relationships between the terminals 211H, 211L, 212H, 212L, 311H, 311L, 312H, and 312L of the power converter corresponding to each module and the storage batteries 203 and 303 corresponding to each module are the same as in the first module 100. Therefore, a detailed explanation of the connection relationships is omitted.

[0098] The main high-potential path 20 connects to the first, second, and third high-potential paths 107, 207, and 307. The main low-potential path 21 connects to the first, second, and third low-potential paths 108, 208, and 308. In other words, each module 100, 200, and 300 is connected in parallel to the electrical load 23.

[0099] In each module 100, 200, and 300, the negative-side switches 184, 284, and 384 are located in the portion of the intermediate paths 109, 209, and 309 that is closer to the negative-side connection portions 102, 202, and 302 than to the connection portions with the first low-potential-side terminals 111L, 211L, and 311L.

[0100] In each module 100, 200, and 300, the switch switching sections 180, 280, and 380 are located in the high-potential paths 107, 207, and 307, on the positive terminal connection sections 101, 201, and 301 side, rather than on the connection section with the first high-potential terminals 111H, 211H, and 311H.

[0101] The control device 170 is capable of performing overcurrent interruption control, similar to the first embodiment. According to this embodiment described above, the same effects as the first embodiment can be achieved.

[0102] <Third Embodiment> The third embodiment will now be described, focusing on the differences from the first embodiment, with reference to the drawings. In this embodiment, the configuration of each module 100, 200, and 300 has been changed, as shown in Figures 8 and 9. First, the changes in the configuration of the secondary circuit 130 will be explained using the first power converter 110 as an example.

[0103] As shown in Figure 8, the secondary circuit 130 includes a first switch SA and a second switch SB as a "secondary switch section". The first switch SA and the second switch SB are semiconductor switching elements, similar to the first embodiment, and specifically N-channel MOSFETs. Each switch SA and SB has body diodes DA and DB.

[0104] The first end of reactor 132 is connected to the drain of the first switch SA and the drain of the second switch SB. The first end of secondary coil 142 is connected to the source of the first switch SA. The second end of secondary coil 142 is connected to the source of the second switch SB.

[0105] The secondary circuits of the second power converter 210 and the third power converter 310 are equipped with a first switch SA and a second switch SB, similar to the secondary circuit 130 of the first power converter 110. In this embodiment, the configurations of the second power converter 210 and the third power converter 310 are basically the same as those of the first power converter 110, so a detailed description of the second power converter 210 and the third power converter 310 is omitted. Each power converter 110, 210, and 310 is configured to operate only in positive voltage mode, out of positive voltage mode and negative voltage mode.

[0106] In this embodiment, overcurrent interruption control is performed using the first and second switches SA and SB located in the secondary circuits of each power converter 110, 210, and 310. In each module 100, 200, and 300, the flow of current in the charging direction of the batteries 103, 203, and 303 is blocked when the first and second switches SA and SB are turned off. On the other hand, the flow of current in the discharging direction of the batteries 103, 203, and 303 is permitted regardless of whether the first and second switches SA and SB are on or off. In this case, there is a concern that overcurrents flowing in the discharging direction of the batteries 103, 203, and 303 cannot be interrupted.

[0107] As shown in Figure 9, the first module 100 is equipped with a first opposing switch SC1. The second module 200 is equipped with a second opposing switch SC2. The third module 300 is equipped with a third opposing switch SC3. Each opposing switch SC1, SC2, and SC3 is a semiconductor switching element, more specifically an N-channel MOSFET. Each opposing switch SC1, SC2, and SC3 has body diodes DC1, DC2, and DC3. The first to third opposing switches SC1 to SC3 correspond to the "opposing switch section".

[0108] Taking the first module 100 as an example, the first opposing switch SC1 is located in the first high-potential path 104. The drain of the first opposing switch SC1 is connected to the second high-potential side terminal 112H. The source of the first opposing switch SC1 is connected to the main high-potential path 20. In the second and third modules 200 and 300, the second and third opposing switches SC2 and SC3 are located in the second and third high-potential paths 204 and 304, respectively, similar to the case of the first opposing switch SC1.

[0109] In this embodiment, the control device 170 can interrupt overcurrents flowing in the discharge direction of the batteries 103, 203, and 303, which are currents flowing through the path including the secondary circuits of the batteries 103, 203, and 303, the power converters 110, 210, and 310, and the electrical load 23, by turning off the opposing switches SC1, SC2, and SC3 in each module 100, 200, and 300. Furthermore, the control device 170 can interrupt overcurrents flowing in the charging direction of the batteries 103, 203, and 303, which are currents flowing through the path including the batteries 103, 203, and 303, the secondary circuits, and the electrical load 23, by turning off the first and second switches SA and SB of the power converters 110, 210, and 310 in each module 100, 200, and 300. Therefore, overcurrents flowing through the path including the batteries 103, 203, and 303, the secondary circuits, and the electrical load 23 can be appropriately interrupted while utilizing the first and second switches SA and SB of the secondary circuits. As a result, it is possible to realize a configuration that can perform overcurrent interruption control while suppressing an increase in the number of components in system 10. For example, compared to the configuration described in Figure 2 above, which has bidirectional first to fourth switches SW1 to SW4 in the secondary circuit, the number of switches added to system 10 to interrupt overcurrent can be reduced.

[0110] Furthermore, each opposing switch SC1, SC2, and SC3 can be used not only to interrupt overcurrents but also to switch the electrical connection between the corresponding modules 100, 200, and 300 and the electrical load 23. In this case, the number of electrical components such as fuses and relays provided in each module 100, 200, and 300 can be reduced compared to a comparative example that does not have each opposing switch SC1, SC2, and SC3. For example, each high-potential path 104, 204, and 304 shown in Figure 9 can be configured without any components for interrupting overcurrents (e.g., fuses) other than the opposing switches SC1, SC2, and SC3. As a result, an increase in the number of components in the system 10 can be suppressed.

[0111] In step S24 of Figure 4, the opposing switches SC1, SC2, and SC3 are turned off. In step S25, the first and second switches SA and SB of the power converters 110, 210, and 310 are turned off. This protects the system 10 in the event of an overcurrent.

[0112] <Modification of the third embodiment> Each opposing switch SC1, SC2, SC3 may be provided as shown in Figures 10 and 11.

[0113] In Figure 10, in each module 100, 200, and 300, the opposing switches SC1, SC2, and SC3 are provided in the intermediate paths 106, 206, and 306, respectively. In detail, using the first module 100 as an example, the first opposing switch SC1 is provided in the portion of the first intermediate path 106 that is closer to the second low-potential terminal 112L than the portion connected to the first high-potential terminal 111H. The drain of the first opposing switch SC1 is connected to the first switch switching unit 180 and the first high-potential terminal 111H. The source of the first opposing switch SC1 is connected to the second low-potential terminal 112L. In the second and third modules 200 and 300, the second and third opposing switches SC2 and SC3 are provided in the second and third intermediate paths 206 and 306, respectively, similar to the case of the first opposing switch SC1.

[0114] In Figure 11, in each module 100, 200, and 300, the opposing switches SC1, SC2, and SC3 are provided in the low-potential paths 105, 205, and 305. In detail, using the first module 100 as an example, the first opposing switch SC1 is provided in the portion of the first low-potential path 105 that is closer to the main low-potential path 21 than the portion connected to the first low-potential side terminal 111L. The drain of the first opposing switch SC1 is connected to the main low-potential path 21. The source of the first opposing switch SC1 is connected to the negative electrode side switch 184 and the first low-potential side terminal 111L. In the second and third modules 200 and 300, the second and third opposing switches SC2 and SC3 are provided in the second and third low-potential paths 205 and 305, respectively, similar to the case of the first opposing switch SC1.

[0115] Each power converter 110, 210, and 310 has the configuration described in Figure 8, and each module 100, 200, and 300 has the configuration described in Figure 7, in which opposing switches SC1, SC2, and SC3 may be provided. For example, as shown in Figures 12, 13, and 14, opposing switches SC1, SC2, and SC3 may be provided.

[0116] In Figure 12, in each module 100, 200, and 300, the opposing switches SC1, SC2, and SC3 are provided in the high-potential paths 107, 207, and 307. In detail, using the first module 100 as an example, the first opposing switch SC1 is provided in the portion of the first high-potential path 107 that is closer to the main high-potential path 20 than the portion connected to the first high-potential side terminal 111H. The drain of the first opposing switch SC1 is connected to the first switch switching unit 180 and the first high-potential side terminal 111H. The source of the first opposing switch SC1 is connected to the main high-potential path 20. In the second and third modules 200 and 300, the second and third opposing switches SC2 and SC3 are provided in the second and third high-potential paths 207 and 307, respectively, similar to the case of the first opposing switch SC1.

[0117] In Figure 13, in each module 100, 200, and 300, the opposing switches SC1, SC2, and SC3 are provided in the intermediate paths 109, 209, and 309. To explain in detail using the first module 100 as an example, the first opposing switch SC1 is provided in the portion of the first intermediate path 109 that is closer to the second high-potential terminal 112H than the portion connected to the first low-potential terminal 111L. The drain of the first opposing switch SC1 is connected to the second high-potential terminal 112H. The source of the first opposing switch SC1 is connected to the negative-side switch 184 and the first low-potential terminal 111L. In the second and third modules 200 and 300, the second and third opposing switches SC2 and SC3 are provided in the second and third intermediate paths 209 and 309, similar to the case of the first opposing switch SC1.

[0118] In Figure 14, in each module 100, 200, and 300, the opposing switches SC1, SC2, and SC3 are provided in the low-potential paths 108, 208, and 308. To explain in detail using the first module 100 as an example, the drain of the first opposing switch SC1 is connected to the main low-potential path 21. The source of the first opposing switch SC1 is connected to the second low-potential side terminal 112L. In the second and third modules 200 and 300, the second and third opposing switches SC2 and SC3 are provided in the second and third low-potential paths 208 and 308, similar to the case of the first opposing switch SC1.

[0119] The opposing switch may be provided in the main high-potential path 20 or the main low-potential path 21. For example, the first opposing switch SC1 may be provided in the main high-potential path 20 in the portion between the connection portion with the first high-potential path 104 and the connection portion with the second high-potential path 204. Even in this case, it is possible to interrupt the overcurrent flowing in the discharge direction in the path including the first storage battery 103, the first power converter 110, and the electrical load 23.

[0120] Each power converter 110, 210, and 310 may be configured to operate only in negative voltage mode, among positive voltage mode and negative voltage mode. Referring to Figure 8, the first end of the reactor 132 is connected to the sources of the first and second switches SA and SB, instead of the drains of the first and second switches SA and SB. The first end of the secondary coil 142 is connected to the drain of the first switch SA. The second end of the secondary coil 142 is connected to the drain of the second switch SB.

[0121] In this embodiment, in each module 100, 200, and 300, the flow of current in the discharge direction to the storage batteries 103, 203, and 303 is prevented by turning off the first and second switches SA and SB. On the other hand, the flow of current in the charging direction to the storage batteries 103, 203, and 303 is permitted regardless of whether the first and second switches SA and SB are on or off.

[0122] Therefore, in the configuration described in Figures 9 to 14 above, the installation configuration of each opposing switch SC1, SC2, SC3 may be changed so that the current allowed by the first and second switches SA and SB can be blocked. For example, in Figure 9, the drain of the first opposing switch SC1 may be connected to the main high-potential path 20, and the source of the first opposing switch SC1 may be connected to the second high-potential side terminal 112H. The second and third opposing switches SC2 and SC3 may be arranged in the second and third high-potential paths 204 and 304, similar to the first opposing switch SC1.

[0123] In step S24 of Figure 4, the first and second switches SA and SB of the power converters 110, 210, and 310 may be turned off. In step S25, the opposing switches SC1, SC2, and SC3 may be turned off.

[0124] <Fourth Embodiment> The fourth embodiment will now be described, focusing on the differences from the third embodiment, with reference to the drawings. In this embodiment, as shown in Figure 15, the system 10 is equipped with a low-voltage load 24. Also, the configuration of the third module 300 has been changed compared to the configuration shown in Figure 9. Note that the power converters 110, 210, and 310 are the same as those described in Figure 8.

[0125] The low-voltage load 24 consists of on-board auxiliary equipment and control devices that can operate when supplied with a voltage lower than the voltage of each battery 103, 203, and 303 (for example, 12V). In this embodiment, the electrical load 23 corresponds to the "high-voltage load".

[0126] The third module 300 includes a first auxiliary path 391 and a second auxiliary path 392 for connecting the low-voltage load 24 and the third power converter 310. The first auxiliary path 391 connects the second high-potential side terminal 312H of the third power converter 310 to the positive side of the low-voltage load 24. The second auxiliary path 392 connects the second low-potential side terminal 312L of the third power converter 310 to the negative side of the low-voltage load 24.

[0127] The third module 300 includes a first auxiliary switch 393 and a second auxiliary switch 394. Each auxiliary switch 393, 394 is either a mechanical relay or a semiconductor switching element. Each auxiliary switch 393, 394, when turned off, prevents the flow of current in both directions, and when turned on, allows the flow of current in both directions. Each auxiliary switch 393, 394 is controlled by the control device 170.

[0128] The first auxiliary switch 393 is located in the first auxiliary path 391. The second auxiliary switch 394 is located in the second auxiliary path 392. When each of the auxiliary switches 393 and 394 is turned on, the second high-potential terminal 312H and the second low-potential terminal 312L of the third power converter 310 are connected in parallel to the low-voltage load 24. Here, it is required that the low-voltage load 24 be electrically isolated from components to which high voltage is applied, such as the third storage battery 303 and the electrical load 23.

[0129] Therefore, the third module 300 includes a first changeover switch Q1 and a second changeover switch Q2. In this embodiment, the first changeover switch Q1 is a semiconductor switching element, similar to the third opposing switch SC3 in the third embodiment, and is specifically an N-channel MOSFET. The first changeover switch Q1 has a body diode Dq. The second changeover switch Q2 prevents the flow of current in both directions when turned off, and allows the flow of current in both directions when turned on. For example, the second changeover switch Q2 is a mechanical relay or a semiconductor switching element. Each changeover switch Q1 and Q2 is controlled by the control device 170.

[0130] The third opposing switch SC3 and the first changeover switch Q1 are located in the third high-potential path 304. The first changeover switch Q1 is connected in series with the third opposing switch SC3 such that when it is turned off, the direction of current flow is opposite to that of the third opposing switch SC3. In Figure 15, the sources of the third opposing switch SC3 and the first changeover switch Q1 are connected to each other. In this case, when both the first changeover switch Q1 and the third opposing switch SC3 are turned off, the bidirectional flow of current through each switch Q1 and SC3 is blocked. The drains of the third opposing switch SC3 and the first changeover switch Q1 may also be connected to each other.

[0131] The second changeover switch Q2 is located in the third intermediate path 306, on the side of the second low-potential terminal 312L rather than the connection portion with the first high-potential terminal 311H. When the third opposing switch SC3 and each changeover switch Q1, Q2 are turned off, electrical isolation is ensured between the secondary circuit of the third power converter 310 and the components to which high voltage is applied.

[0132] In this embodiment, the third opposing switch SC3 can be used not only to interrupt overcurrents but also to ensure electrical isolation when connecting the third power converter 310 to the low-voltage load 24. Therefore, in a configuration in which the third power converter 310 is used to supply power to the low-voltage load 24, it is possible to suppress an increase in the number of switches provided in the system 10.

[0133] For example, the control device 170 may perform the processing described below in overcurrent interruption control. Figure 16 shows the processing procedure for overcurrent interruption control. Here, we will explain assuming a situation in which switching control of the third power converter 310 is performed based on request information before it is determined that an overcurrent has flowed in the third module 300. In this case, the third opposing switch SC3 and each changeover switch Q1, Q2 are turned ON, and each auxiliary switch 393, 394 are turned OFF. In Figure 16, the processing content of each step S20, S21, S22, S24, and S25 shows the processing content of overcurrent interruption control for the third module 300.

[0134] After the processing in step S24, the process proceeds to step S26. In step S26, the selector switches Q1 and Q2 are turned off. This ensures electrical isolation between the secondary circuit of the third power converter 310 and the components to which high voltage is applied. In step S27, the auxiliary switches 393 and 394 are turned on. This electrically connects the low-voltage load 24 to the second high-potential terminal 312H and the second low-potential terminal 312L of the third power converter 310.

[0135] In step S28, the switching control of the third power converter 310 is performed. Specifically, based on the power requirements of the low-voltage load 24, the switching control of the switches S1H, S2H, S1L, and S2L in the primary circuit of the third power converter 310 is performed so that power is transmitted from the primary circuit to the secondary circuit. As a result, power is supplied from the third battery 303 to the low-voltage load 24. The power requirements of the low-voltage load 24 can be those notified by the higher-level control device.

[0136] In this embodiment, if it is determined that an overcurrent is flowing in the third module 300, the third opposing switch SC3 is turned off. Subsequently, the selector switches Q1 and Q2 are turned off, and the auxiliary switches 393 and 394 are turned on. This allows the secondary circuit of the third power converter 310 and the low-voltage load 24 to be electrically connected while ensuring electrical isolation between the low-voltage load 24 and the components to which high voltage is applied, after the overcurrent in the discharge direction has been interrupted. Therefore, even if the overcurrent in the discharge direction is interrupted in the third module 300, the operation of the third power converter 310 can continue, and power can be supplied from the third battery 303 to the low-voltage load 24.

[0137] Furthermore, if there is no request for the control device 170 to supply power from the third power converter 310 to the low-voltage load 24, it is not necessary to perform the processes in steps S26 to S28 after the processing in step S24.

[0138] <Modification of the Fourth Embodiment> The configuration of the third module 300 may be changed from the configuration shown in Figure 10 to configure the third power converter 310 to be connectable to the low-voltage load 24. For example, in Figure 17, the third opposing switch SC3 and the first changeover switch Q1 are provided in the third intermediate path 306, in the portion on the second low-potential side terminal 312L side of the connection portion with the first high-potential side terminal 311H. The second changeover switch Q2 is provided in the third high-potential path 304.

[0139] - The configuration of the third module 300 may be changed from the configuration shown in Figure 13 to enable connection of the third power converter 310 to the low-voltage load 24. For example, in Figure 18, the third opposing switch SC3 and the first changeover switch Q1 are provided in the third intermediate path 309, on the side of the second high-potential terminal 312H rather than the connection portion with the first low-potential terminal 311L. The second changeover switch Q2 is provided in the third low-potential path 308.

[0140] ・The configuration of the third module 300 may be changed from the configuration shown in Figure 14 to enable connection of the third power converter 310 to the low-voltage load 24. For example, in Figure 19, the third opposing switch SC3 and the first changeover switch Q1 are provided in the third low-potential path 308. The second changeover switch Q2 is provided in the third intermediate path 309, in the portion closer to the second high-potential terminal 312H than the portion connected to the first low-potential terminal 311L.

[0141] In the configurations shown in Figures 17, 18, and 19 described above, the control device 170 can perform overcurrent interruption control in the same manner as described in Figure 16.

[0142] The first changeover switch Q1 may be a mechanical relay instead of a semiconductor switching element.

[0143] <Fifth Embodiment> The fifth embodiment will now be described, focusing on the differences from the third embodiment, with reference to the drawings. In this embodiment, the arrangement of the opposing switches SC1, SC2, and SC3 in each module 100, 200, and 300 has been changed. Note that the power converters 110, 210, and 310 have the same configuration as described in Figure 8 above.

[0144] In the following, we will first describe the first module 100 as an example. In Figure 20, the first opposing switch SC1 is provided in the portion of the first intermediate path 106 that is closer to the positive electrode connection portion 101 than the portion that connects to the first high-potential side terminal 111H. The drain of the first opposing switch SC1 is connected to the positive electrode connection portion 101. The source of the first opposing switch SC1 is connected to the first switch switching unit 180.

[0145] Note that the arrangement of the first opposing switch SC1 is not limited to that shown in Figure 20. For example, the drain of the first opposing switch SC1 may be connected to the first switch switching unit 180. The source of the first opposing switch SC1 may be connected to the second low-potential terminal 112L and the first high-potential terminal 111H.

[0146] In this embodiment, the first opposing switch SC1 is provided on a path common to both the current flow path when current flows from the first battery 103 to the first high-potential terminal 111H and the current flow path when current flows from the first battery 103 to the second low-potential terminal 112L. In the second and third modules 200 and 300, similar to the case of the first opposing switch SC1, the second and third opposing switches SC2 and SC3 are provided on the second and third intermediate paths 206 and 306. In this case, in each module 100, 200, and 300, by turning off the opposing switches SC1, SC2, and SC3, the discharge-direction current flowing through the path including the secondary circuits of the batteries 103, 203, and 303 and the power converters 110, 210, and 310 is blocked. In addition, discharge-direction currents flowing through the paths including the primary circuits of the batteries 103, 203, and 303 and the power converters 110, 210, and 310 are blocked. As a result, overcurrents flowing through the primary circuits of each power converter 110, 210, and 310 can be interrupted, and the system 10 can be properly protected.

[0147] For example, the control device 170 may perform overcurrent interruption control to interrupt overcurrent in the discharge direction flowing through the path including the primary side circuits of the storage batteries 103, 203, 303 and the power converters 110, 210, 310.

[0148] To illustrate with an example of overcurrent interruption control for the first module 100, in step S20 of Figure 4, the current flowing through the primary circuit 120 may be obtained. The value detected by the first current sensor 152 can be used as the current flowing through the primary circuit 120.

[0149] In step S21, it may be determined whether the magnitude of the current flowing through the primary circuit 120 is greater than the predetermined discharge value Ida. For example, the predetermined discharge value Ida is determined based on the rated current of the primary circuit 120. This enables overcurrent interruption control suitable for protecting the primary circuit 120.

[0150] Furthermore, a situation in which an overcurrent in the discharge direction flows through the path including the first battery 103 and the primary circuit 120 is assumed to be a short-circuit failure in the primary circuit 120 or the first capacitor 121. A short-circuit failure in the primary circuit 120 is a failure in which the first upper and lower arm switches S1H and S1L are turned on simultaneously, or a failure in which the second upper and lower arm switches S2H and S2L are turned on simultaneously.

[0151] <Modification of the Fifth Embodiment> Each opposing switch SC1, SC2, SC3 may be arranged as shown in Figure 21, for example.

[0152] Using the first module 100 as an example, the first opposing switch SC1 is located in the first low-potential path 105, on the negative electrode connection side 102, rather than the connection portion with the first low-potential terminal 111L. In Figure 21, the first opposing switch SC1 is located in the first low-potential path 105, between the negative electrode connection 102 and the negative electrode switch 184. The drain of the first opposing switch SC1 is connected to the negative electrode switch 184. The source of the first opposing switch SC1 is connected to the negative electrode connection 102.

[0153] In the second and third modules 200 and 300, the second and third opposing switches SC2 and SC3 are provided in the low-potential paths 205 and 305, similar to the case of the first opposing switch SC1.

[0154] Note that the arrangement of each opposing switch SC1, SC2, and SC3 is not limited to that shown in Figure 21. For example, the first opposing switch SC1 may be provided in the portion of the first low-potential path 105 between the connection portion with the first low-potential side terminal 111L and the negative electrode side switch 184. The drain of the first opposing switch SC1 may be connected to the main low-potential path 21 and the first low-potential side terminal 111L. The source of the first opposing switch SC1 may be connected to the negative electrode side switch 184. The second and third opposing switches SC2 and SC3 may be arranged in the second and third low-potential paths 205 and 305 in the same manner as the arrangement of the first opposing switch SC1 described above.

[0155] The configuration of each power converter 110, 210, and 310 may be the configuration described in Figure 8, and the configuration of each module 100, 200, and 300 may be the configuration described in Figure 7. In this case, for example, opposing switches SC1, SC2, and SC3 can be provided as shown in Figures 22 and 23.

[0156] In Figure 22, using the first module 100 as an example, the first opposing switch SC1 is located in the portion of the first high-potential path 107 that is closer to the positive electrode connection portion 101 than the portion connected to the first high-potential side terminal 111H. More specifically, the first opposing switch SC1 is located in the portion of the first high-potential path 107 between the first switch switching portion 180 and the positive electrode connection portion 101. The drain of the first opposing switch SC1 is connected to the positive electrode connection portion 101. The source of the first opposing switch SC1 is connected to the first switch switching portion 180.

[0157] Note that the arrangement of the first opposing switch SC1 is not limited to that shown in Figure 22. For example, the first opposing switch SC1 may be provided in the portion of the first high-potential path 107 between the connection portion with the first high-potential side terminal 111H and the first switch switching unit 180. The drain of the first opposing switch SC1 may be connected to the first switch switching unit 180. The source of the first opposing switch SC1 may be connected to the main high-potential path 20 and the first high-potential side terminal 111H.

[0158] In Figure 23, using the first module 100 as an example, the first opposing switch SC1 is located in the portion of the first intermediate path 109 closer to the negative electrode connection portion 102 than the portion connected to the first low-potential side terminal 111L. More specifically, the first opposing switch SC1 is located in the first intermediate path 109 between the negative electrode connection portion 102 and the negative electrode side switch 184. The drain of the first opposing switch SC1 is connected to the negative electrode side switch 184. The source of the first opposing switch SC1 is connected to the negative electrode connection portion 102.

[0159] Note that the arrangement of the first opposing switch SC1 is not limited to that shown in Figure 23. For example, the first opposing switch SC1 may be provided in the portion of the first intermediate path 109 between the connection portion with the first low-potential side terminal 111L and the negative electrode side switch 184. The drain of the first opposing switch SC1 may be connected to the first low-potential side terminal 111L and the second high-potential side terminal 112H. The source of the first opposing switch SC1 may be connected to the negative electrode side switch 184.

[0160] In Figure 22, the second and third opposing switches SC2 and SC3 are provided in the second and third high-potential paths 207 and 307, similar to the case of the first opposing switch SC1. In Figure 23, the second and third opposing switches SC2 and SC3 are provided in the second and third intermediate paths 209 and 309, similar to the case of the first opposing switch SC1.

[0161] In each module 100, 200, and 300, the opposing switches SC1, SC2, and SC3 may be used not only to interrupt overcurrents but also to switch the electrical connections of the power converters 110, 210, and 310 and the storage batteries 103, 203, and 303. In this case, in Figures 20 and 22, each opposing switch SC1, SC2, and SC3 can substitute for the function of each positive-side switch 183, 283, and 383. In Figures 21 and 23, each opposing switch SC1, SC2, and SC3 can substitute for the function of each negative-side switch 184, 284, and 384. This makes it possible to omit, for example, the installation of the positive-side switches 183, 283, and 383 or the negative-side switches 184, 284, and 384, thereby reducing the number of switches provided in the system 10. Furthermore, for example, in each module 100, 200, 300, redundancy of the functions of the positive-side switches 183, 283, 383 or the negative-side switches 184, 284, 384 can be ensured.

[0162] <Sixth Embodiment> The sixth embodiment will now be described, focusing on the differences from the first embodiment, with reference to the drawings. In this embodiment, the control device 170 performs fault detection processing. Fault detection processing is a process that detects a fault in a switch used to interrupt overcurrent. The control device 170 performs fault detection processing while performing charge control to precharge each capacitor 22, 121, and 131. Charge control is performed, for example, when the vehicle is started, specifically when the system 10 is started. Figure 24 shows the processing procedure for charge control.

[0163] In step S30, it is determined whether or not a pre-charge command has been input from the higher-level control device. If the determination in step S30 is negative, this control is terminated. On the other hand, if it is determined that a pre-charge command has been input from the higher-level control device, the process proceeds to step S31.

[0164] In step S31, it is determined whether the situation was one that was initially determined to be positive in step S30 after the charging control was started. If the determination in step S31 is positive, the process proceeds to step S32. If the determination in step S31 is negative, the process proceeds to step S34.

[0165] In step S32, in each module 100, 200, and 300, the positive side switches 183, 283, and 383, the pre-charge switches 181, 281, and 381, the first to fourth switches SW1 to SW4, and the negative side switches 184, 284, and 384 are turned off.

[0166] In step S33, the precharge switches 181, 281, and 381, the first and third switches SW1 and SW3, and the negative side switches 184, 284, and 384 are switched from off to on in each module 100, 200, and 300. This starts the precharging of the first capacitor 121 and the second capacitor 131 and the smoothing capacitor 22 in each power converter 110, 210, and 310. As shown in Figure 25, when the first and third switches SW1 and SW3 are on and the second and fourth switches SW2 and SW4 are off, the secondary circuit 130 allows current to flow in the discharge direction and prevents current to flow in the charge direction. This allows the capacitors 22, 121, and 131 to be precharged while suppressing the generation of circulating current flowing between each module 100, 200, and 300.

[0167] Next, as a fault detection process, steps S34 and S35 are performed. In step S34, the voltage of the smoothing capacitor 22, the voltage of the second capacitor 131 of each power converter 110, 210, 310, the current flowing through the smoothing capacitor 22, and the current flowing through the second capacitor 131 of each power converter 110, 210, 310 are obtained. For example, the voltage of the smoothing capacitor 22 can be determined using the detected value of the main voltage sensor 30, and the voltage of the second capacitor 131 can be determined using the detected value of the second voltage sensor 154. The current flowing through the smoothing capacitor 22 can be determined using the detected value of the main current sensor 31, and the current flowing through the second capacitor 131 can be determined using the detected value of the second current sensor 153.

[0168] In step S35, a fault diagnosis of the switches is performed based on the voltage and current obtained in step S34. The switches to be diagnosed are the first and third switches SW1 and SW3 in each power converter 110, 210, and 310. In this embodiment, the presence or absence of an off-fixed fault in the first and third switches SW1 and SW3 is diagnosed. An off-fixed fault is a fault in which the switch cannot be switched from off to on. For example, the diagnosis results for the first and third switches SW1 and SW3 are stored in the storage unit 172.

[0169] Here, we will describe an example of fault diagnosis for the first and third switches SW1 and SW3. Figure 26 is a circuit diagram of each capacitor 22, 121, and 131 during precharging. Figure 26 shows the current path for each capacitor 22 and 121 from 0 [V] to 380 [V]. The voltage of the first battery 103 is 380 [V], the voltage of the second battery 203 is 390 [V], and the voltage of the third battery 303 is 400 [V].

[0170] If there is no off-fixation fault in the first and third switches SW1 and SW3 of each power converter 110, 210, and 310, current flows through the system 10 as shown in Figure 26. In this case, the voltage of the smoothing capacitor 22 and the voltage of the first capacitor 121 of each power converter 110, 210, and 310 rise. Also, the voltage of the second capacitor 131 of each power converter 110, 210, and 310 is maintained at approximately 0 [V].

[0171] If an off-fixed fault occurs in any of the first or third switches SW1 or SW3 of each power converter 110, 210, or 310, it is assumed that the pre-charging of each capacitor 22, 121, or 131 will not be performed properly. For example, in a power converter where an off-fixed fault occurs in the first or third switches SW1 or SW3, it is assumed that no discharge current will flow in the secondary circuit. In this case, the pre-charging of the smoothing capacitor 22 may not be completed within a predetermined period. Also, in a power converter where an off-fixed fault occurs, the voltage of the second capacitor 131 may not be maintained at approximately 0 [V].

[0172] The control device 170 determines whether the pre-charging of each capacitor 22, 131 is being performed normally based on the voltage and current obtained by the processing in step S34. For example, the control device 170 determines whether the pre-charging of the smoothing capacitor 22 has been completed within a predetermined period. Also, for example, the control device 170 determines whether the voltage of the second capacitor 131 is being maintained at approximately 0 [V]. If the control device 170 determines that the pre-charging of each capacitor 22, 131 is being performed normally, it diagnoses that there is no off-fixed fault in the first and third switches SW1, SW3 of each power converter 110, 210, 310. If the control device 170 determines that the pre-charging of each capacitor 22, 131 is not being performed normally, it diagnoses that there is an off-fixed fault in one of the first and third switches SW1, SW3 of each power converter 110, 210, 310.

[0173] Returning to the explanation of Figure 24, after the processing in step S35, the process proceeds to step S36. In step S36, it is determined whether or not the pre-charging of each capacitor 22, 121, and 131 is complete. If it is diagnosed that the first and third switches SW1 and SW3 are stuck off, the determination of whether or not the pre-charging is complete should be performed only on the modules 100, 200, and 300 that are not experiencing the off-fixed failure of the first and third switches SW1 and SW3.

[0174] If it is determined in step S36 that precharging is not complete, this series of processes is terminated and the process in step S30 is executed again. On the other hand, if the determination in step S36 is positive, the process proceeds to step S37. In step S37, the precharge switches 181, 281, and 381 are switched off, and the positive side switches 183, 283, and 383 are switched on. Then, this control is terminated.

[0175] According to this embodiment, fault diagnosis can be performed on the first and third switches SW1 and SW3 of each power converter 110, 210, and 310. This allows for the implementation of overcurrent interruption control after confirming that no abnormalities have occurred in the first and third switches SW1 and SW3 used for overcurrent interruption.

[0176] Fault detection processing is performed during the charging control process. This allows for diagnosis of whether or not there are any abnormalities in the first and third switches SW1 and SW3 prior to the startup of system 10.

[0177] <Modification of the 6th Embodiment> In step S34 of Figure 24, it is sufficient to obtain at least one of the following: the voltage of the smoothing capacitor 22, the voltage of the second capacitor 131 of each power converter 110, 210, 310, the current flowing through the smoothing capacitor 22, and the current flowing through the secondary circuits of the power converters 110, 210, 310. Even in this case, the fault diagnosis process described above can still be performed.

[0178] In the configuration of each module 100, 200, and 300 described in the second embodiment, the fault detection process described in Figure 24 above may be performed.

[0179] As shown in Figure 27, fault detection processing may be performed. In this embodiment, fault diagnosis is performed with the first to fourth switches SW1 to SW4 as the detection targets. In this embodiment, the presence or absence of off-locked faults and on-locked faults of the first to fourth switches SW1 to SW4 is diagnosed. An on-locked fault is a fault in which the switch cannot be switched from on to off.

[0180] In step S40, the same process as in step S30 in Figure 24 is performed. If a negative result is obtained in step S40, this control is terminated. On the other hand, if an affirmative result is obtained in step S40, the process proceeds to step S41. In step S41, the same process as in step S32 in Figure 24 is performed.

[0181] In step S42, a module is selected from among modules 100, 200, and 300 to charge the first and second capacitors 121 and 131. For example, the selected module is one of modules 100, 200, and 300 whose first and second capacitors 121 and 131 have not been pre-charged and whose battery voltage 103, 203, and 303 is the lowest. The following steps S43 to S50 are performed on the module selected in step S42.

[0182] In step S43, the precharge switch, the first and third switches SW1 and SW3, and the negative terminal switch are switched from off to on in the selected module. In this case, precharging of the smoothing capacitor 22 and the first capacitor 121 of the power converter is started. As a result, the voltages of each capacitor 22 and 121 rise to the voltage of the storage battery.

[0183] In step S44, the positive side switch is switched from off to on, and the precharge switch is switched from on to off for the selected module.

[0184] In step S45, the power converter in the selected module is operated in negative voltage mode. In step S46, the voltage of the smoothing capacitor 22, the voltage of the second capacitor 131 in the selected module, the current flowing through the smoothing capacitor 22, and the current flowing through the second capacitor 131 in the selected module are obtained. Here, the voltage and current while operating in negative voltage mode are obtained. In step S47, based on the voltage and current obtained in step S46, the presence or absence of on-fixed and off-fixed faults in the first to fourth switches SW1 to SW4 is diagnosed.

[0185] In step S48, the power converter in the selected module is operated in positive voltage mode. In step S49, the same process as in step S46 is performed. Here, the voltage and current while operating in positive voltage mode are acquired. In step S50, based on the voltage and current acquired in step S49, the presence or absence of on-fixed and off-fixed faults in the first to fourth switches SW1 to SW4 is diagnosed.

[0186] Here, we will describe an example of fault diagnosis for the first to fourth switches SW1 to SW4. In steps S45 and S48, for example, the power converter of the selected module is stepped down to negative voltage mode or positive voltage mode. In this case, if there are no off-fixed or on-fixed faults in the first to fourth switches SW1 to SW4 of each power converter 110, 210, and 310, the voltage of the smoothing capacitor 22 and the voltage of the second capacitor 131 of each power converter 110, 210, and 310 are controlled normally.

[0187] Figures 28, 29, and 30 show examples of the step-down operation of each power converter 110, 210, and 310. Figures 28, 29, and 30 assume that there are no off-fixed or on-fixed faults in the first to fourth switches SW1 to SW4 of each power converter 110, 210, and 310. Note that in Figures 28, 29, and 30, the current paths flowing through the secondary circuit side and the smoothing capacitor 22 of each power converter 110, 210, and 310 are not shown.

[0188] In Figure 28, the first module 100 is selected as the module for charging the first and second capacitors 121 and 131. Also, the voltage of the first capacitor 121 and the voltage of the smoothing capacitor 22 of the first power converter 110 have risen to 380 [V]. From this state, the control device 170 steps down the first power converter 110 in negative voltage mode so that the voltage of the second capacitor 131 becomes -10 [V]. Subsequently, the control device 170 steps down the first power converter 110 in positive voltage mode so that the voltage of the second capacitor 131 becomes 10 [V]. As a result, the voltage of the smoothing capacitor 22 changes in the order of 380 [V], 370 [V], and 390 [V].

[0189] In Figure 29, the second module 200 is selected as the module for charging the first and second capacitors 121 and 131. Also, the voltage of the first capacitor 121 and the voltage of the smoothing capacitor 22 of the second power converter 210 have risen to 390 [V]. From this state, the control device 170 steps down the second power converter 210 in negative voltage mode so that the voltage of the second capacitor 131 of the second power converter 210 becomes -10 [V]. Subsequently, the control device 170 steps down the second power converter 210 in positive voltage mode so that the voltage of the second capacitor 131 of the second power converter 210 becomes 10 [V]. As a result, the voltage of the smoothing capacitor 22 changes in the order of 390 [V], 380 [V], and 400 [V]. Furthermore, the control device 170 steps down the first power converter 110 so that the output voltage of the first module 100 becomes equal to the output voltage of the second module 200.

[0190] In Figure 30, the third module 300 is selected as the module for charging the first and second capacitors 121 and 131. Also, the voltage of the first capacitor 121 and the voltage of the smoothing capacitor 22 of the third power converter 310 have risen to 400 [V]. From this state, the control device 170 steps down the third power converter 310 in negative voltage mode so that the voltage of the second capacitor 131 of the third power converter 310 becomes -10 [V]. Subsequently, the control device 170 steps down the third power converter 310 in negative voltage mode so that the voltage of the second capacitor 131 of the third power converter 310 becomes 0 [V]. As a result, the voltage of the smoothing capacitor 22 changes in the order of 400 [V], 390 [V], and 400 [V]. Furthermore, the control device 170 steps down the first and second power converters 110 and 210 so that the output voltages of the first and second modules 100 and 200 become equivalent to the output voltage of the third module 300.

[0191] For example, in step S42, the modules for charging the first and second capacitors 121 and 131 are not limited to being selected in order of increasing voltage of the storage batteries 103, 203, and 303, but may also be selected in order of decreasing voltage. In this case, the control device 170 may operate the third power converter 310 in positive voltage mode to step down. In steps S45 and S48, each power converter 110, 210, and 310 is not limited to being operated in negative voltage mode or positive voltage mode to step down, but may also be operated in negative voltage mode or positive voltage mode to boost the voltage. When each power converter 110, 210, and 310 is operated in negative voltage mode to boost the voltage, the second and fourth switches SW2 and SW4 of the secondary circuit are fixed to ON, and the first and third switches SW1 and SW3 are switched ON and OFF. When each power converter 110, 210, and 310 is operated in positive voltage boost mode, the first and third switches SW1 and SW3 of the secondary circuit are fixed to the ON position, and the second and fourth switches SW2 and SW4 are switched on and off. Furthermore, the processes in steps S48 to S50 may be executed before the processes in steps S45 to S47. Also, only one of the processes in steps S45 to S47 or steps S48 to S50 may be executed.

[0192] If an off-fixed or on-fixed failure occurs in any of the first to fourth switches SW1 to SW4 while the power converter of the selected module is operating, it is expected that the voltages of each capacitor 22, 131 will not be controlled properly. For example, the voltage of the second capacitor 131 may not be controlled to the expected voltage (e.g., the command voltage).

[0193] In step S47, the control device 170 determines whether the voltage of the second capacitor 131 of the selected module is being controlled normally based on the voltage and current obtained in step S46. For example, it determines whether the voltage of the second capacitor 131 of the selected module is being controlled to a negative voltage. In step S50, the control device 170 determines whether the voltage of the second capacitor 131 of the selected module is being controlled normally based on the voltage and current obtained in step S49. For example, it determines whether the voltage of the second capacitor 131 of the selected module is being controlled to a positive voltage. If the control device 170 determines that the voltage of the second capacitor 131 of the selected module is being controlled normally, it diagnoses that there are no off-fixed or on-fixed faults in the first to fourth switches SW1 to SW4. If the control device 170 determines that the voltage of the second capacitor 131 of the selected module is not being controlled normally, it diagnoses that there is an off-fixed or on-fixed fault in one of the first to fourth switches SW1 to SW4.

[0194] Returning to the explanation of step S27, in step S51, it is determined whether the pre-charging of the first and second capacitors 121 and 131 has been completed in each module 100, 200, and 300. If the determination in step S51 is positive, this control is terminated. On the other hand, if the determination in step S51 is negative, the process in step S42 is executed again.

[0195] According to this embodiment, fault diagnosis can be performed on the first to fourth switches SW1 to SW4 of each power converter 110, 210, and 310. This allows overcurrent interruption control to be performed after confirming that no abnormalities have occurred in the first to fourth switches SW1 to SW4 used for overcurrent interruption.

[0196] In step S46 of Figure 27, it is sufficient to obtain at least one of the following: the voltage of the smoothing capacitor 22, the voltage of the second capacitor 131 in the selected module, the current flowing through the smoothing capacitor 22, and the current flowing through the second capacitor 131 in the selected module. Even in this case, the fault diagnosis process described above can still be performed.

[0197] <Seventh Embodiment> The seventh embodiment will be described below, focusing on the differences from the third and sixth embodiments, with reference to the drawings. In this embodiment, the control device 170 performs fault detection processing on each of the opposing switches SC1, SC2, and SC3 as detection targets during the implementation of charge control. The following description assumes a configuration in which each of the opposing switches SC1, SC2, and SC3 is arranged as described in Figure 9 above.

[0198] Figure 31 shows the processing procedure for charge control.

[0199] In steps S60 and S61, the same processing as in steps S30 and S31 in Figure 24 is performed. If a positive determination is made in step S61, the process proceeds to step S62. In step S62, the positive side switches 183, 283, and 383, the pre-charge switches 181, 281, and 381, the opposing switches SC1, SC2, and SC3, and the negative side switches 184, 284, and 384 are turned off in each module 100, 200, and 300.

[0200] In step S63, the precharge switches 181, 281, and 381 and the negative terminal switches 184, 284, and 384 are switched from off to on in each module 100, 200, and 300. This starts the precharging of the first capacitor 121 of each power converter 110, 210, and 310. Subsequently, the fault detection process is carried out in steps S64 and S5.

[0201] In step S64, the voltage of the smoothing capacitor 22, the voltages of the first and second capacitors 121 and 131 of each power converter 110, 210, and 310, the current flowing through the smoothing capacitor 22, and the current flowing through the first and second capacitors 121 and 131 of each power converter 110, 210, and 310 are obtained. For example, the voltage of the first capacitor 121 can be determined using the value detected by the first voltage sensor 151, and the current flowing through the first capacitor 121 can be determined using the value detected by the first current sensor 152.

[0202] In step S65, based on the voltage and current obtained in step S64, it is diagnosed whether or not each of the opposing switches SC1, SC2, and SC3 is stuck in the ON position.

[0203] Here, we will describe an example of diagnosing an ON-fixed fault in each opposing switch SC1, SC2, and SC3. Figure 32 is a circuit diagram after the process in step S63 of Figure 31 has been performed, and during the pre-charging of the first capacitors 121 of each power converter 110, 210, and 310. Figure 32 shows the current path during the period when the voltage of the first capacitors 121 of each power converter 110, 210, and 310 goes from 0 [V] to 380 [V].

[0204] If there is no ON-fixed failure in each of the opposing switches SC1, SC2, and SC3, current flows through the system 10 as shown in Figure 32, and only the first capacitor 121 among the capacitors 22, 121, and 131 is pre-charged. In this case, the voltage of the first capacitor 121 of each power converter 110, 210, and 310 rises. The voltage of the smoothing capacitor 22 and the second capacitor 131 of each power converter 110, 210, and 310 are maintained at approximately 0 [V].

[0205] If an ON-lock failure occurs in at least one of the opposing switches SC1, SC2, and SC3, it is expected that precharging will occur unintentionally in the smoothing capacitor 22 and the second capacitor 131 among the capacitors 22, 121, and 131. For example, current may flow in the secondary circuit of a power converter where an ON-lock failure has occurred in an opposing switch, potentially causing the voltage of the smoothing capacitor 22 to rise.

[0206] Based on the voltage and current obtained in step S64, the control device 170 determines whether precharging is being performed on only the first capacitor 121 among the capacitors 22, 121, and 131. For example, the control device 170 determines whether the voltage of the first capacitor 121 is equal to or greater than a predetermined charge determination voltage, and whether the voltages of the smoothing capacitor 22 and the second capacitor 131 are less than the maintenance determination voltage. The maintenance determination voltage is a value near 0 [V], for example, higher than 0 [V] and less than 1 [V], 3 [V], or 5 [V]. If the control device 170 determines that precharging is being performed on only the first capacitor 121 among the capacitors 22, 121, and 131, it diagnoses that no ON-fixed failure has occurred in each of the opposing switches SC1, SC2, and SC3. If the control device 170 determines that precharging is not being performed properly only on the first capacitor 121 among the capacitors 22, 121, and 131, it diagnoses that an ON-fixed failure has occurred in at least one of the opposing switches SC1, SC2, and SC3.

[0207] Returning to the explanation of Figure 31, in step S66, each opposing switch SC1, SC2, and SC3 is switched from off to on. This starts the pre-charging of the smoothing capacitor 22 and the second capacitor 131 of each power converter 110, 210, and 310. Subsequently, the fault detection process is carried out in steps S67 and S68.

[0208] In step S67, the same process as in step S64 is performed. In step S68, based on the voltage and current obtained in step S67, it is diagnosed whether or not there is an off-fixed fault in each of the opposing switches SC1, SC2, and SC3.

[0209] Here, we will describe an example of diagnosing an off-fixed fault in each of the opposing switches SC1, SC2, and SC3. Figure 33 is a circuit diagram after the process in step S66 of Figure 31 has been performed, and during the pre-charging of the smoothing capacitor 22. Figure 32 shows the current path during the period when the voltage of the smoothing capacitor 22 goes from 0 [V] to 380 [V].

[0210] If there is no ON-fixed failure in the opposing switches SC1, SC2, and SC3 of each power converter 110, 210, and 310, current flows to the system 10 as shown in Figure 33, and the smoothing capacitor 22 is pre-charged normally. In this case, the voltage of the smoothing capacitor 22 rises. The second capacitor 131 of each power converter 110, 210, and 310 is maintained at approximately 0 [V].

[0211] If at least one of the opposing switches SC1, SC2, and SC3 is stuck in the "off" position, it is assumed that the pre-charging of the smoothing capacitor 22 will not be performed properly. For example, the pre-charging of the smoothing capacitor 22 may not be completed within a predetermined period.

[0212] The control device 170 determines whether the pre-charging of the smoothing capacitor 22 is being performed normally based on the voltage and current obtained in step S67. For example, the control device 170 determines whether the pre-charging of the smoothing capacitor 22 has been completed within a predetermined period. If the control device 170 determines that the pre-charging of the smoothing capacitor 22 is being performed normally, it diagnoses that there is no off-fixed failure in each of the opposing switches SC1, SC2, and SC3. If the control device 170 determines that the pre-charging of the smoothing capacitor 22 is not being performed normally, it diagnoses that there is an off-fixed failure in at least one of the opposing switches SC1, SC2, and SC3.

[0213] Returning to the explanation of Figure 31, if a negative result is obtained in step S61, or after processing in step S68, the process proceeds to step S69. In steps S69 and S70, the same processing as in steps S36 and S37 of Figure 24 is performed.

[0214] According to this embodiment, fault diagnosis can be performed on each of the opposing switches SC1, SC2, and SC3. This allows overcurrent interruption control to be performed after confirming that no abnormalities have occurred in each of the opposing switches SC1, SC2, and SC3 used for overcurrent interruption.

[0215] <Modification of the 7th Embodiment> The fault detection process described in Figure 31 may be applied to the configuration shown in Figures 10-14, 15, and 17-19.

[0216] ・The fault detection process described in Figure 31 may be applied to the configuration described in the fifth embodiment. Below, an example of on-lock fault diagnosis and off-lock fault diagnosis for each opposing switch SC1, SC2, and SC3 will be described using the configuration shown in Figure 20 as an example. Note that on-lock fault diagnosis and off-lock fault diagnosis for each opposing switch SC1, SC2, and SC3 can also be performed for the configurations shown in Figures 21 to 23.

[0217] As shown in Figure 34, if there is no ON-fixed failure in each of the opposing switches SC1, SC2, and SC3, the capacitors 22, 121, and 131 are not pre-charged after the process in step S63 of Figure 31. Therefore, the voltage of each capacitor 22, 121, and 131 is maintained at approximately 0 [V].

[0218] If an ON-fixed failure occurs in at least one of the opposing switches SC1, SC2, and SC3, it is expected that the voltages of the smoothing capacitor 22, the first capacitor 121, and the second capacitor 131 will rise after the process in step S63 of Figure 31 has been performed.

[0219] The control device 170 determines whether the voltage across each capacitor 22, 121, and 131 is below a predetermined voltage based on the voltage and current obtained in step S64. For example, the predetermined voltage is higher than 0 [V] and less than 1 [V], 3 [V], or 5 [V]. If the control device 170 determines that the voltage across each capacitor 22, 121, and 131 is below the predetermined voltage, it diagnoses that there is no ON-fixed fault in each opposing switch SC1, SC2, and SC3. If the control device 170 determines that the voltage across each capacitor 22, 121, and 131 is above the predetermined voltage, it diagnoses that there is an ON-fixed fault in each opposing switch SC1, SC2, and SC3.

[0220] As shown in Figure 35, if no off-fixation failure occurs in each of the opposing switches SC1, SC2, and SC3, pre-charging of the smoothing capacitor 22 and the first capacitor 121 is performed after the processing of step S66 in Figure 31. In this case, the voltage of the smoothing capacitor 22 and the voltage of the first capacitor 121 of each power converter 110, 210, and 310 rise appropriately. Figure 35 shows the current path during the period when the voltages of the smoothing capacitor 22 and the first capacitor 121 reach 380 [V] from 0 [V].

[0221] If at least one of the opposing switches SC1, SC2, and SC3 is stuck in the "off" position, it is expected that the pre-charging of the smoothing capacitor 22 and the first capacitor 121 will not be performed properly after the processing in step S66 of Figure 31. For example, the pre-charging of the smoothing capacitor 22 and the first capacitor 121 may not be completed within a predetermined period.

[0222] The control device 170 determines whether the pre-charging of the smoothing capacitor 22 and the first capacitor 121 is performed normally based on the voltage and current obtained in step S67. For example, the control device 170 determines whether the pre-charging of the smoothing capacitor 22 and the first capacitor 121 is completed within a predetermined period. If the control device 170 determines that the pre-charging of the smoothing capacitor 22 and the first capacitor 121 is performed normally, it diagnoses that there is no off-fixed fault in each of the opposing switches SC1, SC2, and SC3. If the control device 170 determines that the pre-charging of the smoothing capacitor 22 and the first capacitor 121 is not performed normally, it diagnoses that there is an off-fixed fault in each of the opposing switches SC1, SC2, and SC3.

[0223] <Other Embodiments> The above embodiments may be modified and implemented as follows.

[0224] In the first and second embodiments, the configuration of the secondary circuits of each power converter 110, 210, and 310 may be, for example, the configurations shown in Figures 36 and 37. Hereinafter, Figures 36 and 37 will be explained with reference to the drawings, focusing on the differences from Figure 2.

[0225] In Figure 36, the secondary circuit 130 includes first to fourth switches K1 to K4. The first to fourth switches K1 to K4 are semiconductor switching elements, specifically N-channel MOSFETs. Each switch K1, K2, K3, and K4 has a body diode DK1, DK2, DK3, and DK4.

[0226] The sources of the first switch K1 and the second switch K2 are connected to each other. The drain of the second switch K2 is connected to the first end of the secondary coil 142. The drain of the first switch K1 is connected to the second low-potential terminal 112L. The sources of the third switch K3 and the fourth switch K4 are connected to each other. The drain of the fourth switch K4 is connected to the second end of the secondary coil 142. The drain of the third switch K3 is connected to the second low-potential terminal 112L. The first end of the reactor 132 is connected to the center tap 143 of the secondary coil 142. The second end of the reactor 132 is connected to the second high-potential terminal 112H.

[0227] In the configuration shown in Figure 36, overcurrent interruption control and fault detection processing are possible. In this case, the descriptions of the first, second, third, and fourth switches SW1, SW2, SW3, and SW4 in Figures 4, 24, and 27 above should be replaced with the first, second, third, and fourth switches K1, K2, K3, and K4.

[0228] In Figure 37, the secondary circuit 130 is a full-bridge circuit instead of a center-tapped circuit. The secondary circuit 130 includes a first switch section U1, a second switch section U2, a third switch section U3, and a fourth switch section U4. The switches constituting each of the switch sections U1 to U4 are semiconductor switching elements, specifically N-channel MOSFETs.

[0229] The first switch section U1 comprises a series connection of a first H switch UH1 and a first L switch UL1, with their sources connected to each other. The second switch section U2 comprises a series connection of a second H switch UH2 and a second L switch UL2, with their sources connected to each other. The third switch section U3 comprises a series connection of a third H switch UH3 and a third L switch UL3, with their sources connected to each other. The fourth switch section U4 comprises a series connection of a fourth H switch UH4 and a fourth L switch UL4, with their sources connected to each other. Each switch UH1, UL1, UH2, UL2, UH3, UL3, UH4, UL4 has body diodes DH1, DL1, DH2, DL2, DH3, DL3, DH4, DL4.

[0230] The first end of the reactor 132 is connected to the second low-potential terminal 112L via a series connection of the first switch section U1 and the second switch section U2. The first end of the reactor 132 is also connected to the second low-potential terminal 112L via a series connection of the third switch section U3 and the fourth switch section U4. The first end of the secondary coil 142 is connected to the connection point of the first switch section U1 and the second switch section U2. The second end of the secondary coil 142 is connected to the connection point of the third switch section U3 and the fourth switch section U4.

[0231] In the configuration shown in Figure 37, overcurrent interruption control and fault detection processing are possible. In this case, the descriptions of the first and third switches SW1 and SW3 in Figures 4, 24, and 27 above should be replaced with the first to fourth L switches UL1 to UL4. Also, the descriptions of the second and fourth switches SW2 and SW4 in Figures 4, 24, and 27 above should be replaced with the first to fourth H switches UH1 to UH4.

[0232] In the third, fourth, and fifth embodiments, each power converter 110, 210, and 310 is not limited to the configuration described in Figure 8. For example, each power converter 110, 210, and 310 may be configured to include only the second and fourth switches K2 and K4 from the first to fourth switches K1 to K4 in the configuration shown in Figure 36. Alternatively, each power converter 110, 210, and 310 may be configured to include only the first to fourth H switches UH1 to UH4 from the first to fourth H switches UH1 to UH4 and the first to fourth L switches UL1 to UL4 in the configuration shown in Figure 37. In this case as well, each power converter 110, 210, and 310 is capable of operating only in positive voltage mode among positive voltage mode and negative voltage mode.

[0233] In each power converter 110, 210, and 310, the switches in the primary and secondary circuits may be N-channel IGBTs instead of N-channel MOSFETs. In this case, freewheeling diodes are connected in antiparallel to the switches in the primary and secondary circuits.

[0234] For example, in Figure 38, the first to fourth switches T1 to T4 in the secondary circuit 130 are N-channel IGBTs. In this case, freewheeling diodes DD1 to DD4 are connected in antiparallel to each of the switches T1 to T4. The collector of the first switch T1 is connected to the first terminal of the secondary coil 142. The emitter of the first switch T1 is connected to the emitter of the second switch T2. The collector of the third switch T3 is connected to the second terminal of the secondary coil 142. The emitter of the third switch T3 is connected to the emitter of the fourth switch T4. The collectors of the second switch T2 and the fourth switch T4 are connected to the first terminal of the reactor 132. In the example shown in Figure 38, the second and fourth switches T2 and T4 and the freewheeling diodes DD2 and DD4 correspond to the "secondary side switch section," while the first and third switches T1 and T3 and the freewheeling diodes DD1 and DD3 correspond to the "opposite switch section."

[0235] In the configuration shown in Figure 38, overcurrent interruption control and fault detection processing are possible. In this case, the descriptions of the first, second, third, and fourth switches SW1, SW2, SW3, and SW4 in Figures 4, 24, and 27 above should be replaced with the first, second, third, and fourth switches T1, T2, T3, and T4. Note that the configuration is not limited to that shown in Figure 38; the collectors of the first and third switches T1 and T3 may be connected to each other. Also, the collectors of the second and fourth switches T2 and T4 may be connected to each other.

[0236] In the first and second embodiments, the configuration of the secondary circuit 130 may be, for example, the configuration shown in Figure 39. Hereinafter, Figure 39 will be described with reference to the drawing, focusing on the differences from the first embodiment. The secondary circuit 130 includes first to fourth switches J1 to J4. The first and second switches J1 and J2 are connected in antiparallel to each other and constitute a reverse-blocking IGBT (RB-IGBT). The third and fourth switches J3 and J4 are connected in antiparallel to each other and constitute a reverse-blocking IGBT.

[0237] In the configuration shown in Figure 39, overcurrent interruption control and fault detection processing are possible. In this case, the descriptions of the first, second, third, and fourth switches SW1, SW2, SW3, and SW4 in Figures 4, 24, and 27 above should be replaced with the first, second, third, and fourth switches J1, J2, J3, and J4.

[0238] In the third to sixth embodiments, the first to third opposing switches may be N-channel IGBTs instead of N-channel MOSFETs. In this case, a freewheeling diode is connected in antiparallel to each opposing switch. In this embodiment, each opposing switch, which is an N-channel IGBT, and the freewheeling diode constitute the "opposing switch section".

[0239] As shown in Figures 40 and 41, the series connection of precharge switches 181, 281, 381 and precharge resistors 182, 282, 382 may be connected in parallel to the negative-side switches 184, 284, 384 instead of the positive-side switches 183, 283, 383. In this case, in each module 100, 200, 300, the precharge switches 181, 281, 381, precharge resistors 182, 282, 382 and negative-side switches 184, 284, 384 constitute the switch switching section 180, 280, 380.

[0240] In the configuration shown in Figures 40 and 41, fault detection processing is possible. In this case, in step S33 of Figure 24, the negative side switches 184, 284, and 384 should be read as positive side switches 183, 283, and 383, and in step S37, the positive side switches 183, 283, and 383 should be read as negative side switches 184, 284, and 384. Also, in step S44 of Figure 27, the positive side switches 183, 283, and 383 should be read as negative side switches 184, 284, and 384.

[0241] In the configuration shown in Figures 9-15 and 17-23, the series connection of precharge switches 181, 281, 381 and precharge resistors 182, 282, 382 may be connected in parallel to the negative-side switches 184, 284, 384 instead of the positive-side switches 183, 283, 383. Even in this case, fault detection processing is still possible. Specifically, in step S63 of Figure 31, the negative-side switches 184, 284, 384 should be replaced with the positive-side switches 183, 283, 383, and in step S70, the positive-side switches 183, 283, 383 should be replaced with the negative-side switches 184, 284, 384.

[0242] The number of modules in system 10 is not limited to three; it may be two, four or more. In Figure 42, system 10 has two modules. In this case, system 10 may also have a series switch 400 that connects the first battery 103 and the second battery 203 in series. The series switch 400 connects the positive terminal connection 101 of the first module 100 and the negative terminal connection 202 of the second module 200. The series switch 400 is controlled by the control device 170.

[0243] The control device 170 turns on the negative electrode switch 184, the series switch 400, and the positive electrode switch 283, and turns off the positive electrode switch 183 and the negative electrode switch 284. As a result, the first battery 103 and the second battery 203 are connected in series.

[0244] The precharge switches 181, 281, 381, the positive-side switches 183, 283, 383, and the negative-side switches 184, 284, 384 may be replaced with semiconductor switching elements instead of mechanical relays.

[0245] The electrical loads connected to system 10 are not limited to the inverter 23a and the rotating electric machine 23b. For example, the electrical loads may be an external charger, a power supply unit, a DC-DC converter, a heater, etc.

[0246] An external charger is, for example, a stationary charger installed on the outside of the vehicle. During charging of each battery 103, 203, and 303 by the external charger, it is expected that an overcurrent will flow in the charging direction of each battery 103, 203, and 303.

[0247] The power supply recipients are, for example, grid power or electrical equipment in a building such as a residence. During power supply from each of the batteries 103, 203, and 303 to the power supply recipients, it is expected that an overcurrent will flow in the discharge direction of each of the batteries 103, 203, and 303.

[0248] The power converter is not limited to those described in Figure 2, etc., but can also be used, for example, non-isolated DC-DC converters such as resonant DC-DC converters and buck converters.

[0249] The number of modules in system 10 may be one, two, or four or more. In this case, each module can be configured in the same way as the modules described in the first to fifth embodiments, the modifications of the first to fifth embodiments, and other embodiments.

[0250] The energy storage unit in each module is not limited to a battery; for example, it may include a large-capacity electric double-layer capacitor, or both a battery and an electric double-layer capacitor. Furthermore, the energy storage unit may also be a fuel cell.

[0251] The system 10 is not limited to being mounted on a vehicle; for example, it may be mounted on an aircraft or a ship. If the ship is an aircraft, the rotating electric motor will be the aircraft's power source for flight, and if the ship is a ship, the rotating electric motor will be the ship's power source for navigation. Furthermore, the system 10 is not limited to being mounted on a ship; it can also be used as a stationary power source.

[0252] In this disclosure or claims, the term "processor" means one or more hardware processors configured to execute processing defined by computer program code (i.e., one or more instructions of a computer program) contained in a computer program by reading the computer program code each time. In other words, a "processor" is a hardware device that executes one or more programmed processes. Therefore, computer program code can also be said to be software that can define the processing of the processor according to its content. A "processor" can be a general-purpose or specific-purpose processor, and may be, but is not limited to, a CPU, microprocessor, GPU, and DFP (Data Flow Processor).

[0253] In this disclosure or claims, the term “memory” means one or more hardware memories that are non-transitional tangible recording media configured to record computer program code and / or data in a manner accessible from a processor. “Memory” can be implemented by memory technology such as SRAM, SDRAM, non-volatile / flash type memory, or other types of memory. The computer program code that constitutes the program is recorded in memory and executed by a processor, thereby enabling the processor to perform the various functions described above.

[0254] In this disclosure or claims, the term “circuit” refers to one or more logic circuits as hardware, configured to perform specific processing defined by a pre-designed circuit configuration. In other words (and, in contrast to “processor”), “circuit” in this disclosure or claims refers to a hardware device that performs specific processing based on a circuit configuration, rather than processing defined by software such as the computer program code described above. For example, “circuit” may include custom ICs such as ASICs (Application Specific Integrated Circuits) and FPGAs (Field Programmable Gate Arrays) designed with Hardware Description Language (HDL). That is, “circuit” in this disclosure or claims includes all hardware circuits except for the processors described above that perform processing by reading computer program code.

[0255] In this disclosure or claims, the expression "at least one of the circuit and processor" should be interpreted as disjunctive (logical OR) and not as "at least one circuit and at least one processor." Therefore, in this disclosure or claims, "at least one of the circuit and processor causes the control device to perform functions" includes cases where the circuit alone causes the control device to perform all functions. Also, "at least one of the circuit and processor causes the control device to perform functions" includes cases where the processor alone causes the control device to perform all functions. Furthermore, "at least one of the circuit and processor causes the control device to perform functions" includes cases where the circuit causes the control device to perform some functions and the processor causes the control device to perform the remaining functions. In the last example, for example, if the control device performs functions A to C, functions A and B may be implemented by the circuit, and the remaining function C may be implemented by the processor.

[0256] The following describes characteristic configurations extracted from each of the embodiments described above. [Configuration 1] A system (10) comprising positive electrode connection parts (101, 201, 301) connectable to the positive electrode terminals of the energy storage unit (103, 203, 303), negative electrode connection parts (102, 202, 302) connectable to the negative electrode terminals of the energy storage unit, and a power converter (110, 210, 310), wherein the power converter includes a primary side circuit (120) including first high-potential side terminals (111H, 211H, 311H) and first low-potential side terminals (111L, 211L, 311L), The primary circuit and the secondary circuit are connected, and the secondary circuit (130) includes a second high-potential side terminal (112H, 212H, 312H), a second low-potential side terminal (112L, 212L, 312L), and a secondary side switch section (SW2, SW4, SA, SB, K2, K4, UH1 to UH4, T2, T4, DD2, DD4, J2, J4), and an isolation transformer (140) connecting the primary circuit and the secondary circuit, wherein the secondary side switch section blocks the flow of either the current flowing from the second high-potential side terminal to the second low-potential side terminal or the current flowing from the second low-potential side terminal to the second high-potential side terminal when it is turned off, and allows the flow of the other regardless of whether it is turned on or off, the first high-potential side terminal is connected to the positive electrode connection section, and the first low-potential side terminal is connected to the negative electrode connection section. A system comprising: high-potential paths (104, 204, 304) connecting the second high-potential terminal and the electrical load (23); intermediate paths (106, 206, 306) connecting the second low-potential terminal and the positive electrode connection; low-potential paths (105, 205, 305) connecting the negative electrode connection and the electrical load; and opposing switch sections (SW1, SW3, SC1 to SC3, K1, K3, UL1 to UL4, T1, T3, DD1, DD3, J1, J3) that, when turned off, block the flow of current permitted by the secondary side switch section.[Configuration 2] A system (10) comprising positive electrode connection parts (101, 201, 301) connectable to the positive electrode terminals of the energy storage units (103, 203, 303), negative electrode connection parts (102, 202, 302) connectable to the negative electrode terminals of the energy storage units, and a power converter (110, 210, 310), wherein the power converter includes a primary circuit (120) including first high-potential side terminals (111H, 211H, 311H) and first low-potential side terminals (111L, 211L, 311L), The primary circuit and the secondary circuit are connected, and the secondary circuit (130) includes a second high-potential side terminal (112H, 212H, 312H), a second low-potential side terminal (112L, 212L, 312L), and a secondary side switch section (SW2, SW4, SA, SB, K2, K4, UH1 to UH4, T2, T4, DD2, DD4, J2, J4), and an isolation transformer (140) connecting the primary circuit and the secondary circuit, wherein the secondary side switch section blocks the flow of either the current flowing from the second high-potential side terminal to the second low-potential side terminal or the current flowing from the second low-potential side terminal to the second high-potential side terminal when it is turned off, and allows the flow of the other regardless of whether it is turned on or off, the first high-potential side terminal is connected to the positive electrode connection section, and the first low-potential side terminal is connected to the negative electrode connection section. A system comprising: high-potential paths (107, 207, 307) connecting the positive electrode connection and the electrical load (23); intermediate paths (109, 209, 309) connecting the negative electrode connection and the second high-potential terminal; low-potential paths (108, 208, 308) connecting the second low-potential terminal and the electrical load; and opposing switch sections (SW1, SW3, SC1 to SC3, K1, K3, UL1 to UL4, T1, T3, DD1, DD3, J1, J3) that, when turned off, block the flow of current permitted by the secondary switch section. [Configuration 3] The system according to Configuration 1 or 2, wherein the opposing switch section (SW1, SW3, K1, K3, UL1 to UL4, T1, T3, DD1, DD3, J1, J3) is provided in the secondary circuit, and the secondary switch section and the opposing switch section are connected such that the direction of current flow blocked when they are turned off is in opposite directions to each other.[Configuration 4] The system according to Configuration 1 or 2, wherein the opposing switch units (SC1 to SC3) are provided in any of the high-potential path, the intermediate path, and the low-potential path. [Configuration 5] The system according to Configuration 4, wherein the first high-potential side terminal is connected to an intermediate portion of the intermediate path and connected to the positive electrode connection portion via a part of the intermediate path, the first low-potential side terminal is connected to an intermediate portion of the low-potential path and connected to the negative electrode connection portion via a part of the low-potential path, and the opposing switch unit is provided in the portion of the intermediate path closer to the positive electrode connection portion than the connection point with the first high-potential side terminal, or in the portion of the low-potential path closer to the negative electrode connection portion than the connection point with the first low-potential side terminal. [Configuration 6] The electrical load is a high-voltage load, the second high-potential side terminal and the second low-potential side terminal are connectable in parallel to a low-voltage load (24) that operates when a voltage lower than the voltage of the energy storage unit is supplied, the first high-potential side terminal is connected to an intermediate portion of the intermediate path and connected to the positive electrode connection portion via a part of the intermediate path, the first low-potential side terminal is connected to an intermediate portion of the low-potential path and connected to the negative electrode connection portion via a part of the low-potential path, and the opposing switch portion is provided in the high-potential path or the intermediate path in a portion on the side of the second low-potential side terminal that is connected to the connection point with the first high-potential side terminal, as described in Configuration 4. [Configuration 7] The opposing switch portion is provided in any of the high-potential path, the intermediate path and the low-potential path, as described in Configuration 2. [Configuration 8] The system according to Configuration 7, wherein the first high-potential terminal is connected to an intermediate portion of the high-potential path and connected to the positive electrode connection portion via a portion of the high-potential path, the first low-potential terminal is connected to an intermediate portion of the intermediate path and connected to the negative electrode connection portion via a portion of the intermediate path, and the opposing switch portion is provided in the portion of the high-potential path closer to the positive electrode connection portion than the connection point with the first high-potential terminal, or in the portion of the intermediate path closer to the negative electrode connection portion than the connection point with the first low-potential terminal.[Configuration 9] The system according to Configuration 7, wherein the electrical load is a high-voltage load, the second high-potential side terminal and the second low-potential side terminal are connectable in parallel to a low-voltage load (24) that operates when a voltage lower than the voltage of the energy storage unit is supplied, the first high-potential side terminal is connected to an intermediate portion of the high-potential path and connected to the positive electrode connection portion via a portion of the low-potential path, the first low-potential side terminal is connected to an intermediate portion of the intermediate path and connected to the negative electrode connection portion via a portion of the intermediate path, and the opposing switch portion is provided in the portion of the intermediate path closer to the second high-potential side terminal than the connection point with the first low-potential side terminal, or in the low-potential path. [Configuration 10] The system according to any one of Configurations 1 to 9, comprising a plurality of modules (100, 200, 300) having the positive electrode connection portion, the negative electrode connection portion and the power converter, and each module and the electrical load are connected via the high-potential path and the low-potential path. [Configuration 11] The system according to any one of Configurations 1 to 10, comprising a control device (170) that performs a switch control process to turn off the secondary side switch unit or the opposing switch unit in order to interrupt the overcurrent flowing through the high-potential path, the intermediate path, and the low-potential path. [Configuration 12] The system according to Configuration 11, wherein the control device performs a process including: a determination process to determine whether or not an overcurrent is flowing from the second low-potential side terminal to the second high-potential side terminal; and the switch control process, and in the switch control process, if it is determined in the determination process that an overcurrent is flowing, the system turns off the switch of the secondary side switch unit and the opposing switch unit that is capable of blocking the flow of current from the second low-potential side terminal to the second high-potential side terminal.[Configuration 13] The control device performs a process including: a determination process to determine whether or not an overcurrent is flowing from the second high-potential terminal to the second low-potential terminal; and a switch control process, wherein in the switch control process, if it is determined in the determination process that an overcurrent is flowing, the system according to Configuration 11 or 12 turns off the switch among the secondary side switch unit and the opposing switch unit that is capable of blocking the flow of current from the second high-potential terminal to the second low-potential terminal. [Configuration 14] The system according to any one of Configurations 11 to 13, wherein the primary circuit includes a first capacitor (121) connecting the first high-potential terminal and the first low-potential terminal, the secondary circuit includes a second capacitor (131) connecting the second high-potential terminal and the second low-potential terminal, and comprises a smoothing capacitor (22) connecting the high-potential path and the low-potential path, and the control device performs a process to detect a fault in the opposing switch section based on at least one of the voltage of the first capacitor, the voltage of the second capacitor, the voltage of the smoothing capacitor, the current flowing through the first capacitor, the current flowing through the second capacitor, and the current flowing through the smoothing capacitor while performing charge control to charge the first capacitor, the second capacitor, and the smoothing capacitor.[Configuration 15] The opposing switch section (SW1, SW3, K1, K3, UL1 to UL4, T1, T3, DD1, DD3, J1, J3) is provided in the secondary circuit, the secondary switch section and the opposing switch section are connected such that the direction of current flow blocked when switched off is in opposite directions, the secondary circuit includes a second capacitor (131) connecting the second high-potential terminal and the second low-potential terminal, and a smoothing capacitor (22) connecting the high-potential path and the low-potential path, the control device performs switching control of the power converter by selecting either a positive voltage mode in which the voltage at the second high-potential terminal is higher than that at the second low-potential terminal, or a negative voltage mode in which the voltage at the second low-potential terminal is higher than that at the second high-potential terminal, and performs a process of charging and discharging the second capacitor and the smoothing capacitor, The system according to any one of configurations 11 to 14, which includes a process for detecting a fault in the opposing switch section based on at least one of the voltage of the second capacitor, the voltage of the smoothing capacitor, the current flowing through the second capacitor, and the current flowing through the smoothing capacitor during the execution of the switching control.

[0257] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

Claims

1. A system (10) comprising positive terminal connectors (101, 201, 301) connectable to the positive terminals of a power storage unit (103, 203, 303), negative terminal connectors (102, 202, 302) connectable to the negative terminals of the power storage unit, and a power converter (110, 210, 310), wherein the power converter includes a primary circuit (120) including first high-potential terminals (111H, 211H, 311H) and first low-potential terminals (111L, 211L, 311L), The primary circuit and the secondary circuit are connected, and the secondary circuit (130) includes a second high-potential side terminal (112H, 212H, 312H), a second low-potential side terminal (112L, 212L, 312L), and a secondary side switch section (SW2, SW4, SA, SB, K2, K4, UH1 to UH4, T2, T4, DD2, DD4, J2, J4), and an isolation transformer (140) connecting the primary circuit and the secondary circuit, wherein the secondary side switch section blocks the flow of either the current flowing from the second high-potential side terminal to the second low-potential side terminal or the current flowing from the second low-potential side terminal to the second high-potential side terminal when it is turned off, and allows the flow of the other regardless of whether it is turned on or off, the first high-potential side terminal is connected to the positive electrode connection section, and the first low-potential side terminal is connected to the negative electrode connection section. A system comprising: high-potential paths (104, 204, 304) connecting the second high-potential terminal and the electrical load (23); intermediate paths (106, 206, 306) connecting the second low-potential terminal and the positive electrode connection; low-potential paths (105, 205, 305) connecting the negative electrode connection and the electrical load; and opposing switch sections (SW1, SW3, SC1 to SC3, K1, K3, UL1 to UL4, T1, T3, DD1, DD3, J1, J3) that, when turned off, block the flow of current permitted by the secondary side switch section.

2. In a system (10) comprising positive terminal connectors (101, 201, 301) connectable to the positive terminals of the energy storage units (103, 203, 303), negative terminal connectors (102, 202, 302) connectable to the negative terminals of the energy storage units, and power converters (110, 210, 310), the power converter includes a primary circuit (120) including first high-potential terminals (111H, 211H, 311H) and first low-potential terminals (111L, 211L, 311L), The primary circuit and the secondary circuit are connected, and the secondary circuit (130) includes a second high-potential side terminal (112H, 212H, 312H), a second low-potential side terminal (112L, 212L, 312L), and a secondary side switch section (SW2, SW4, SA, SB, K2, K4, UH1 to UH4, T2, T4, DD2, DD4, J2, J4), and an isolation transformer (140) connecting the primary circuit and the secondary circuit, wherein the secondary side switch section blocks the flow of either the current flowing from the second high-potential side terminal to the second low-potential side terminal or the current flowing from the second low-potential side terminal to the second high-potential side terminal when it is turned off, and allows the flow of the other regardless of whether it is turned on or off, the first high-potential side terminal is connected to the positive electrode connection section, and the first low-potential side terminal is connected to the negative electrode connection section. A system comprising: high-potential paths (107, 207, 307) connecting the positive electrode connection and the electrical load (23); intermediate paths (109, 209, 309) connecting the negative electrode connection and the second high-potential terminal; low-potential paths (108, 208, 308) connecting the second low-potential terminal and the electrical load; and opposing switch sections (SW1, SW3, SC1 to SC3, K1, K3, UL1 to UL4, T1, T3, DD1, DD3, J1, J3) that, when turned off, block the flow of current permitted by the secondary switch section.

3. The system according to claim 1 or 2, wherein the opposing switch section (SW1, SW3, K1, K3, UL1 to UL4, T1, T3, DD1, DD3, J1, J3) is provided in the secondary circuit, and the secondary switch section and the opposing switch section are connected such that the direction of current flow blocked when they are turned off is in opposite directions to each other.

4. The system according to claim 1, wherein the opposing switch sections (SC1 to SC3) are provided in any of the high-potential path, the intermediate path, and the low-potential path.

5. The system according to claim 4, wherein the first high-potential terminal is connected to an intermediate portion of the intermediate path and connected to the positive electrode connection portion via a portion of the intermediate path; the first low-potential terminal is connected to an intermediate portion of the low-potential path and connected to the negative electrode connection portion via a portion of the low-potential path; and the opposing switch portion is provided in the portion of the intermediate path closer to the positive electrode connection portion than the connection point with the first high-potential terminal, or in the portion of the low-potential path closer to the negative electrode connection portion than the connection point with the first low-potential terminal.

6. The system according to claim 4, wherein the electrical load is a high-voltage load, the second high-potential terminal and the second low-potential terminal are connectable in parallel to a low-voltage load (24) that operates when a voltage lower than the voltage of the energy storage unit is supplied, the first high-potential terminal is connected to an intermediate portion of the intermediate path and connected to the positive electrode connection portion via a portion of the intermediate path, the first low-potential terminal is connected to an intermediate portion of the low-potential path and connected to the negative electrode connection portion via a portion of the low-potential path, and the opposing switch portion is provided in the high-potential path or the intermediate path in a portion on the side of the second low-potential terminal that is connected to the first high-potential terminal.

7. The system according to claim 2, wherein the opposing switch section is provided in any of the high-potential path, the intermediate path, and the low-potential path.

8. The system according to claim 7, wherein the first high-potential terminal is connected to an intermediate portion of the high-potential path and connected to the positive electrode connection portion via a portion of the high-potential path; the first low-potential terminal is connected to an intermediate portion of the intermediate path and connected to the negative electrode connection portion via a portion of the intermediate path; and the opposing switch portion is provided in the portion of the high-potential path closer to the positive electrode connection portion than the connection point with the first high-potential terminal, or in the portion of the intermediate path closer to the negative electrode connection portion than the connection point with the first low-potential terminal.

9. The system according to claim 7, wherein the electrical load is a high-voltage load, the second high-potential terminal and the second low-potential terminal are connectable in parallel to a low-voltage load (24) that operates when a voltage lower than the voltage of the energy storage unit is supplied, the first high-potential terminal is connected to an intermediate portion of the high-potential path and connected to the positive electrode connection portion via a portion of the low-potential path, the first low-potential terminal is connected to an intermediate portion of the intermediate path and connected to the negative electrode connection portion via a portion of the intermediate path, and the opposing switch portion is provided in the portion of the intermediate path closer to the second high-potential terminal than the connection point with the first low-potential terminal, or in the low-potential path.

10. The system according to any one of claims 1, 2, 4 to 9, comprising a plurality of modules (100, 200, 300) having the positive electrode connection portion, the negative electrode connection portion, and the power converter, wherein each module and the electrical load are connected via the high-potential path and the low-potential path.

11. The system according to any one of claims 1, 2, 4 to 9, further comprising a control device (170) that performs switch control processing to turn off the secondary side switch unit or the opposing switch unit in order to interrupt the overcurrent flowing through the high-potential path, the intermediate path, and the low-potential path.

12. The control device performs a process including: a determination process for determining whether or not an overcurrent is flowing from the second low-potential terminal to the second high-potential terminal; and a switch control process, wherein in the switch control process, if it is determined in the determination process that an overcurrent is flowing, the system according to claim 11 is turned off the switch among the secondary side switch unit and the opposing switch unit that is capable of blocking the flow of current from the second low-potential terminal to the second high-potential terminal.

13. The system according to claim 11, wherein the control device performs a process including: a determination process for determining whether or not an overcurrent is flowing from the second high-potential terminal to the second low-potential terminal; and a switch control process, and in the switch control process, if it is determined in the determination process that an overcurrent is flowing, the system turns off the switch among the secondary side switch unit and the opposing switch unit that is capable of blocking the flow of current from the second high-potential terminal to the second low-potential terminal.

14. The system according to claim 11, wherein the primary circuit includes a first capacitor (121) connecting the first high-potential terminal and the first low-potential terminal, the secondary circuit includes a second capacitor (131) connecting the second high-potential terminal and the second low-potential terminal, and comprises a smoothing capacitor (22) connecting the high-potential path and the low-potential path, and the control device performs a process to detect a fault in the opposing switch section based on at least one of the voltage of the first capacitor, the voltage of the second capacitor, the voltage of the smoothing capacitor, the current flowing through the first capacitor, the current flowing through the second capacitor, and the current flowing through the smoothing capacitor while performing charge control to charge the first capacitor, the second capacitor, and the smoothing capacitor.

15. The system according to claim 11, wherein the secondary circuit includes a second capacitor (131) connecting the second high-potential terminal and the second low-potential terminal, and a smoothing capacitor (22) connecting the high-potential path and the low-potential path, and the control device performs switching control of the power converter by selecting either a positive voltage mode in which the voltage at the second high-potential terminal is higher than that at the second low-potential terminal, or a negative voltage mode in which the voltage at the second low-potential terminal is higher than that at the second high-potential terminal, thereby charging and discharging the second capacitor and the smoothing capacitor, and during the execution of the switching control, performs a process to detect a fault in the opposing switch section based on at least one of the voltage at the second capacitor, the voltage at the smoothing capacitor, the current flowing through the second capacitor, and the current flowing through the smoothing capacitor.

16. In a program applied to a system (10) comprising positive terminal connectors (101, 201, 301) connectable to the positive terminals of a power storage unit (103, 203, 303), negative terminal connectors (102, 202, 302) connectable to the negative terminals of the power storage unit, and a power converter (110, 210, 310), the power converter comprises a primary circuit (120) including first high-potential terminals (111H, 211H, 311H) and first low-potential terminals (111L, 211L, 311L), The system comprises: a secondary circuit (130) including second high-potential terminals (112H, 212H, 312H), second low-potential terminals (112L, 212L, 312L), and secondary switch sections (SW2, SW4, SA, SB, K2, K4, UH1 to UH4, T2, T4, DD2, DD4, J2, J4); and an isolation transformer (140) connecting the primary circuit and the secondary circuit, wherein the secondary switch section blocks the flow of either the current flowing from the second high-potential terminal to the second low-potential terminal or the current flowing from the second low-potential terminal to the second high-potential terminal when it is turned off, and allows the flow of the other regardless of whether it is on or off; the first high-potential terminal is connected to the positive electrode connection section; and the first low-potential terminal is connected to the negative electrode connection section. A program comprising: high-potential paths (104, 204, 304) connecting the second high-potential terminal and an electrical load (23); intermediate paths (106, 206, 306) connecting the second low-potential terminal and the positive electrode connection; low-potential paths (105, 205, 305) connecting the negative electrode connection and the electrical load; and opposing switch units (SW1, SW3, SC1 to SC3, K1, K3, UL1 to UL4, T1, T3, DD1, DD3, J1, J3) that, when turned off, prevent the flow of current permitted by the secondary side switch unit, wherein the program causes at least one of the processor (171) and the circuit to execute a switch control process to turn off the secondary side switch unit or the opposing switch unit in order to interrupt overcurrent flowing through the high-potential paths, the intermediate paths, and the low-potential paths.

17. In a program applied to a system (10) comprising positive terminal connectors (101, 201, 301) connectable to the positive terminals of a power storage unit (103, 203, 303), negative terminal connectors (102, 202, 302) connectable to the negative terminals of the power storage unit, and a power converter (110, 210, 310), the power converter comprises a primary circuit (120) including first high-potential terminals (111H, 211H, 311H) and first low-potential terminals (111L, 211L, 311L), The system comprises: a secondary circuit (130) including second high-potential terminals (112H, 212H, 312H), second low-potential terminals (112L, 212L, 312L), and secondary switch sections (SW2, SW4, SA, SB, K2, K4, UH1 to UH4, T2, T4, DD2, DD4, J2, J4); and an isolation transformer (140) connecting the primary circuit and the secondary circuit, wherein the secondary switch section blocks the flow of either the current flowing from the second high-potential terminal to the second low-potential terminal or the current flowing from the second low-potential terminal to the second high-potential terminal when it is turned off, and allows the flow of the other regardless of whether it is turned on or off; the first high-potential terminal is connected to the positive electrode connection section; the first low-potential terminal is connected to the negative electrode connection section; and the system is A program comprising: high-potential paths (107, 207, 307) connecting the positive electrode connection and an electrical load (23); intermediate paths (109, 209, 309) connecting the negative electrode connection and the second high-potential terminal; low-potential paths (108, 208, 308) connecting the second low-potential terminal and the electrical load; and opposing switch sections (SW1, SW3, SC1 to SC3, K1, K3, UL1 to UL4, T1, T3, DD1, DD3, J1, J3) that, when turned off, prevent the flow of current permitted by the secondary switch section, wherein the program causes at least one of the processor (171) and the circuit to execute a switch control process to turn off the secondary switch section or the opposing switch section in order to interrupt overcurrent flowing through the high-potential path, the intermediate path, and the low-potential path.

18. A system control method applicable to a system (10) comprising positive terminal connectors (101, 201, 301) connectable to the positive terminals of energy storage units (103, 203, 303), negative terminal connectors (102, 202, 302) connectable to the negative terminals of the energy storage units, and power converters (110, 210, 310), wherein the power converter comprises a primary circuit (120) including first high-potential side terminals (111H, 211H, 311H) and first low-potential side terminals (111L, 211L, 311L), The system comprises: a secondary circuit (130) including second high-potential terminals (112H, 212H, 312H), second low-potential terminals (112L, 212L, 312L), and secondary switch sections (SW2, SW4, SA, SB, K2, K4, UH1 to UH4, T2, T4, DD2, DD4, J2, J4); and an isolation transformer (140) connecting the primary circuit and the secondary circuit, wherein the secondary switch section blocks the flow of either the current flowing from the second high-potential terminal to the second low-potential terminal or the current flowing from the second low-potential terminal to the second high-potential terminal when it is turned off, and allows the flow of the other regardless of whether it is on or off; the first high-potential terminal is connected to the positive electrode connection section; and the first low-potential terminal is connected to the negative electrode connection section. A system control method comprising: high-potential paths (104, 204, 304) connecting the second high-potential terminal and an electrical load (23); intermediate paths (106, 206, 306) connecting the second low-potential terminal and the positive electrode connection; low-potential paths (105, 205, 305) connecting the negative electrode connection and the electrical load; and opposing switch sections (SW1, SW3, SC1 to SC3, K1, K3, UL1 to UL4, T1, T3, DD1, DD3, J1, J3) that, when turned off, prevent the flow of current permitted by the secondary side switch section, wherein the system control method causes a processor (171) and at least one of the circuits to execute a switch control process to turn off the secondary side switch section or the opposing switch section in order to interrupt overcurrent flowing through the high-potential paths, the intermediate paths, and the low-potential paths.

19. A system control method applicable to a system (10) comprising positive terminal connectors (101, 201, 301) connectable to the positive terminals of energy storage units (103, 203, 303), negative terminal connectors (102, 202, 302) connectable to the negative terminals of the energy storage units, and power converters (110, 210, 310), wherein the power converter includes a primary circuit (120) including first high-potential side terminals (111H, 211H, 311H) and first low-potential side terminals (111L, 211L, 311L), The system comprises: a secondary circuit (130) including second high-potential terminals (112H, 212H, 312H), second low-potential terminals (112L, 212L, 312L), and secondary switch sections (SW2, SW4, SA, SB, K2, K4, UH1 to UH4, T2, T4, DD2, DD4, J2, J4); and an isolation transformer (140) connecting the primary circuit and the secondary circuit, wherein the secondary switch section blocks the flow of either the current flowing from the second high-potential terminal to the second low-potential terminal or the current flowing from the second low-potential terminal to the second high-potential terminal when it is turned off, and allows the flow of the other regardless of whether it is turned on or off; the first high-potential terminal is connected to the positive electrode connection section; the first low-potential terminal is connected to the negative electrode connection section; and the system is A system control method comprising: high-potential paths (107, 207, 307) connecting the positive electrode connection and an electrical load (23); intermediate paths (109, 209, 309) connecting the negative electrode connection and the second high-potential terminal; low-potential paths (108, 208, 308) connecting the second low-potential terminal and the electrical load; and opposing switch sections (SW1, SW3, SC1 to SC3, K1, K3, UL1 to UL4, T1, T3, DD1, DD3, J1, J3) that, when turned off, prevent the flow of current permitted by the secondary switch section, wherein the system control method causes at least one of the processor (171) and the circuit to execute a switch control process to turn off the secondary switch section or the opposing switch section in order to interrupt overcurrent flowing through the high-potential path, the intermediate path, and the low-potential path.

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