Power supply system

Abstract

To specify a battery circuit module in which leakage occurs when the leakage occurs in a battery string.SOLUTION: A battery string St is configured such that a plurality of battery circuit modules M can be connected in series. In a leakage diagnosis mode, a control device 100 cuts off a relay 40 and turns on a third switch 60 provided in a ground line GL. The battery circuit module M is switched to a driving state in order from the battery circuit module M close to a negative electrode line PL to the battery circuit module M on a positive electrode line PL side. When a current detected by a current sensor 50 provided in the ground line GL does not change, it is determined that leakage occurs in the battery circuit module M in the driving state.SELECTED DRAWING: Figure 3

Description

Technical Field

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[0001] This disclosure relates to a power supply system.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2022-120255 (Patent Document 1) discloses a power supply system that outputs AC power (AC voltage) using a battery string in which a plurality of battery circuit modules can be connected in series. The battery circuit modules included in the battery string include a battery, a first switch connected in parallel to the battery, a second switch connected in series to the battery, and first and second output terminals to which the voltage of the battery is applied when the first switch is in the OFF state and the second switch is in the ON state. The ON / OFF states of the first switch and the second switch are controlled by a gate drive signal, and the gate drive signal is transmitted to the next-stage battery circuit module connected in series with a predetermined delay time. By controlling the first switch and the second switch of each battery circuit module included in the battery string with a gate drive signal, the output voltage of the battery string can be adjusted to a desired magnitude.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When leakage occurs in an electric circuit (power circuit) including a power supply system, there is also a possibility that leakage has occurred in the battery circuit modules included in the battery string. In Patent Document 1, no mention is made of identifying the location of leakage in the battery string.

[0005] The purpose of this disclosure is to identify the battery circuit module where a leakage current is occurring in a battery string. [Means for solving the problem]

[0006] (1) The power supply system of the present disclosure comprises a battery circuit module, a battery string in which a plurality of battery circuit modules are connected in series, and a control device for controlling the battery string. The battery circuit module includes a battery, a first switch connected in parallel to the battery, a second switch connected in series to the battery, and a first output terminal and a second output terminal to which the battery voltage is applied when the first switch is OFF and the second switch is ON. The power supply system further comprises a ground wire that grounds the negative terminal wire of the battery string, and a current sensor, a third switch, and a limiting resistor provided on the ground wire. The control device is switchable between a drive state in which the first switch is OFF and the second switch is ON, and a through state in which the first switch is ON and the second switch is OFF. In the leakage current diagnosis mode, the control device is configured to turn on the third switch, switch one battery circuit module to the drive state and the other battery circuit modules to the through state, and sequentially switch the battery circuit modules in the drive state to determine which battery circuit module is leaking current based on the current value detected by the current sensor.

[0007] In this configuration, the number of connected battery circuit modules is controlled by controlling the duty cycle of the first and second switches of the battery circuit module, thereby controlling the output voltage of the battery string. The negative terminal of the battery string is grounded by a ground wire via a current sensor, a third switch, and a limiting resistor. In this disclosure, "grounding" may refer to a frame ground connecting the ground wire to the housing of the power system, or it may refer to a connection to the ground.

[0008] When in leakage current diagnosis mode, the control unit turns on the third switch. The control unit then puts one battery circuit module into a driven state (first switch OFF and second switch ON) and the other battery circuit modules into a bypass state (first switch ON and second switch OFF), and sequentially switches the driven battery circuit module. Based on the current value detected by the current sensor when the driven battery circuit module is switched, the control unit determines which battery circuit module is leaking current.

[0009] In leakage current diagnosis mode, the third switch is ON, so the negative terminal of the battery string becomes ground potential via the ground wire. If a leakage current occurs in any of the battery circuit modules included in the battery string, the potential of the battery circuit module experiencing the leakage current becomes ground potential. Therefore, when a battery circuit module on the negative terminal side of the battery circuit module experiencing the leakage current becomes active, a closed circuit is formed connecting the active battery circuit module, the leakage point, and the ground point of the ground wire. The voltage of the active battery circuit module changes the current detected by the current sensor. Also, even if a battery circuit module on the positive terminal side, including the battery circuit module experiencing the leakage current, becomes active, a closed circuit including the active battery circuit module is not formed, so the current detected by the current sensor does not change. Therefore, by sequentially switching the active battery circuit modules, it is possible to determine which battery circuit module is experiencing the leakage current based on the current value detected by the current sensor, and thus identify the battery circuit module experiencing the leakage current.

[0010] (2) In the leakage current diagnosis mode, the control device may sequentially switch the battery circuit module in the driving state from the battery circuit module on the negative terminal side to the battery circuit module on the positive terminal side of the battery string, and determine that the battery circuit module in the driving state where the current value does not change is leaking current.

[0011] With this configuration, the battery circuit modules are switched to the driving state sequentially, starting from the one closest to the negative terminal. Therefore, it is possible to determine that a battery circuit module is leaking current when the current value detected by the current sensor does not change.

[0012] (3) In leakage current diagnosis mode, the control device may sequentially switch the battery circuit module in operation from the battery circuit module on the positive terminal side of the battery string to the battery circuit module on the negative terminal side, and when the current value changes, determine that the battery circuit module that was in operation just before is leaking current.

[0013] With this configuration, the battery circuit modules are switched to the operating state sequentially, starting with those closest to the positive electrode. Therefore, when the current value detected by the current sensor changes, it can be determined that the battery circuit module that was previously in the operating state is experiencing a short circuit.

[0014] (4) In (1) to (3) above, the battery string is connected to the load, and the control device may disconnect the battery string from the load when starting the leakage current diagnostic mode.

[0015] With this configuration, even if the load connected to the battery string is connected to the power grid or has another power supply system, the control unit disconnects the connection between the battery string and the load when initiating the leakage current diagnostic mode, thus reliably identifying the battery circuit module that is leaking current.

[0016] (5) In the above (4), the control device may start a leakage current diagnosis mode when a leakage current is detected in an electrical circuit including a load.

[0017] With this configuration, when a ground fault is detected in an electrical circuit including a load, if a ground fault occurs in a battery circuit module included in the battery string, the battery circuit module causing the ground fault can be identified. [Effects of the Invention]

[0018] According to the present disclosure, when leakage occurs in a battery string, it becomes possible to identify a battery circuit module in which the leakage occurs.

Brief Description of the Drawings

[0019] [Figure 1] It is a diagram showing a partial configuration of a power supply system according to an embodiment of the present disclosure. [Figure 2] (A) to (D) are diagrams for explaining the operation of a battery circuit module controlled by a gate signal. [Figure 3] It is a diagram showing the overall schematic configuration of the power supply system in the present embodiment. [Figure 4] (A) and (B) are diagrams for explaining a closed circuit formed when leakage occurs in a battery circuit module. [Figure 5] (A) and (B) are diagrams for explaining a closed circuit formed when leakage occurs in a battery circuit module. [Figure 6] It is a flowchart showing an example of the process of the leakage diagnosis mode executed by the control device. [Figure 7] In a modified example, it is a flowchart showing the process of the leakage diagnosis mode executed by the control device.

Embodiments for Carrying Out the Invention

[0020] Embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0021] Figure 1 is a diagram showing a partial configuration of a power supply system 1 according to an embodiment of the present disclosure. Referring to Figure 1, the power supply system 1 includes a battery string St and a control device 100. The control device 100 may be a computer and, for example, comprises a processor, a storage device, and a communication interface (I / F). The storage device stores, for example, a program executed by the processor and information used by the program (for example, maps, formulas, and various parameters).

[0022] A battery string St comprises multiple battery circuit modules M (M1 to Mn: n is a positive integer). The number of battery circuit modules M included in the battery string St is arbitrary, and may be 5 to 50 or 100 or more.

[0023] Each battery circuit module M includes a power circuit SUB and a cartridge Cg. The cartridge Cg includes a battery B and a monitoring unit BS. The battery circuit module M, which includes battery B, is formed by connecting the power circuit SUB and battery B. The drive circuits SU (SU1 to SUn) are configured to drive the switching elements (SW11 and SW12, described later) included in the battery circuit module M. Battery B may be a nickel-metal hydride secondary battery or a lithium-ion secondary battery, and may be manufactured by connecting secondary batteries used in electric vehicles in series.

[0024] As shown in Figure 1, the battery circuit module M includes a power circuit SUB, a cartridge Cg, and circuit breakers RB1 and RB2 (hereinafter referred to as "circuit breakers RB" unless otherwise specified). The power circuit SUB and cartridge Cg are connected to each other via circuit breakers RB1 and RB2. The circuit breakers RB switch the connection state (continuity / interruption) between the power circuit SUB and cartridge Cg according to a command from the control device 100. The circuit breakers RB may be configured to be manually turned ON / OFF by the user, and this configuration makes the cartridge Cg detachable from the power circuit SUB.

[0025] In cartridge Cg, the monitoring unit BS is configured to detect the state of battery B (for example, voltage, current, and temperature) and output the detection results to the control device 100.

[0026] The battery circuit modules M included in the battery string St are connected by a common wire SL. The wire SL includes the output terminals OT1 and OT2 of each battery circuit module M. The battery circuit modules M included in the battery string St are connected to each other by the connection of the output terminal OT2 of one battery circuit module M to the output terminal OT1 of an adjacent battery circuit module M.

[0027] The power circuit SUB comprises a first switching element 11 (hereinafter referred to as "SW11"), a second switching element 12 (hereinafter referred to as "SW12"), a first diode 13, a second diode 14, a choke coil 15, a capacitor 16, and output terminals OT1 and OT2. Each of SW11 and SW12 is driven by a drive circuit SU. SW11 and SW12 in this embodiment correspond to examples of the "first switch" and "second switch" according to this disclosure, respectively.

[0028] A switch (SW11), a capacitor (16), and a battery (B) are connected in parallel between the output terminals OT1 and OT2 of the power circuit SUB. The SW11 is located on the wire SL and is configured to switch the connection state (continuity / disconnection) between output terminals OT1 and OT2. Output terminal OT1 is connected to the positive terminal of battery B via wire BL1, and output terminal OT2 is connected to the negative terminal of battery B via wire BL2. A switch (SW12) and a choke coil (15) are further provided on wire BL1. In the battery circuit module M, the voltage of battery B is applied between output terminals OT1 and OT2 when SW12, which is connected in series with battery B, is in the ON state (connected state), and SW11, which is connected in parallel with battery B, is in the OFF state (disconnected state).

[0029] A capacitor 16 is provided between the output terminals OT1 and OT2 and battery B, connected to wires BL1 and BL2, respectively. SW11 and SW12 are, for example, FETs (field-effect transistors). The first diode 13 and the second diode 14 are connected in parallel to SW11 and SW12, respectively, and function as freewheeling diodes. Note that SW11 and SW12 are not limited to FETs, but may be switching elements other than FETs.

[0030] The control device 100 generates gate signals. Each battery circuit module M (M1 to Mn) is provided with a drive circuit SU (SU1 to SUn), which includes a gate driver (GD) 21 that drives SW11 and SW12 according to the gate signal, and a delay circuit 22 that delays the gate signal. Each of SW11 and SW12 in the battery circuit module M is controlled ON / OFF according to the gate signal.

[0031] Figure 2 illustrates the operation of the battery circuit module M controlled by a gate signal. Figure 2(A) is a time chart showing an example of the operation of the battery circuit module M. In this embodiment, a square wave signal is used as the gate signal to drive SW11 and SW12. "Low" and "High" in Figure 2(A) refer to the L level and H level of the gate signal (square wave signal), respectively. "Output voltage" refers to the voltage output between output terminals OT1 and OT2. In the initial state of the battery circuit module M, no gate signal is input to the drive circuit SU (gate signal = L level), and SW11 and SW12 are in the ON and OFF states, respectively. SW11 and SW12 switch states (ON / OFF) according to the rising / falling edge of the gate signal. The control device 100 performs PWM control using the gate signal.

[0032] When a gate signal is input to the drive circuit SU, GD21 drives SW11 and SW12 according to the input gate signal. In the example shown in Figure 2, at timing t1, the gate signal rises from L level to H level, and SW11 switches from the ON state to the OFF state simultaneously with the rise of the gate signal. Then, at timing t2, which is delayed by a predetermined time (dead time dt1) from the rise of the gate signal, SW12 switches from the OFF state to the ON state. As a result, the battery circuit module M enters a driven state (connected state), and as shown in Figure 2(B), with SW11 in the OFF state and SW12 in the ON state, the voltage of battery B is applied between the output terminals OT1 and OT2. In this disclosure, the state in which "SW11 is in the OFF state and SW12 is in the ON state" and the battery circuit module M is in a connected state is referred to as the "driven state".

[0033] Referring to Figure 2(A), at timing t3, when the gate signal falls from a high level to a low level, SW12 switches from the ON state to the OFF state simultaneously with the falling edge of the gate signal. This puts the battery circuit module M into a bypass state. In the bypass state of the battery circuit module M, SW12 is in the OFF state, so the voltage of battery B is no longer applied between the output terminals OT1 and OT2. Subsequently, at timing t4, which is delayed by a predetermined time (dead time dt2) from the falling edge of the gate signal, SW11 switches from the OFF state to the ON state. Note that dead times dt1 and dt2 may be the same or different from each other.

[0034] During dead times dt1 and dt2, both SW11 and SW12 are in the OFF state, as shown in Figure 2(C). This prevents SW11 and SW12 from being in the ON state simultaneously (which would cause the battery circuit module M to be short-circuited).

[0035] The period from the end of the dead time dt2 (t4) until the battery circuit module M enters an operating state is referred to as the "stop period." During the stop period, as shown in Figure 2(D), SW11 is in the ON state and SW12 is in the OFF state, similar to the initial state. In this disclosure, the state in which "SW11 is in the ON state and SW12 is in the OFF state," and the battery circuit module M is in a non-operating state, is also referred to as the "through state."

[0036] The gate signal is delayed by a predetermined delay time Td by the delay circuit 22 and transmitted from the upstream drive circuit SU to the downstream drive circuit SU. When the control device 100 receives the gate signal from the delay circuit 22 of the furthest downstream drive circuit SU (SUn), it outputs a new gate signal to the furthest upstream drive circuit SU (SU0). The period T of the gate signal is the sum of the delay times Td of the delay circuits 22 included in the battery string St. If No is the total number of battery circuit modules M included in the battery string St, then the period T is set as "T = Td × No". By controlling the duty cycle of the gate signal (H level time: on time Ton), the number of battery circuit modules M in the driven state (the number of battery circuit modules M that are driven at the same time) can be adjusted.

[0037] By controlling the battery circuit modules M included in the battery string St as described above, the number of battery circuit modules M in the driven state (the number of battery circuit modules M that are driven simultaneously) can be adjusted. This allows control of the voltage (output voltage) between the positive terminal 25 and the negative terminal 26 of the battery string St. As a result, the battery string St is capable of outputting a voltage from 0[V] to the sum of the voltages of each battery B (cartridge Cg) included in the battery string St.

[0038] Figure 3 shows the overall schematic configuration of the power supply system 1 in this embodiment. The positive terminal 25 of the battery string St is connected to the positive wire PL, and the negative terminal 26 is connected to the negative wire NL. A smoothing capacitor 30 is provided between the positive wire PL and the negative wire NL, and the positive wire PL and the negative wire NL are connected to the load via a relay 40. In the battery circuit module Mn and the drive circuit SUn, the symbol n is "1" (battery circuit module M1, drive circuit SU1) on the side furthest from the positive wire PL (upstream side), and "n" (battery circuit module Mn, drive circuit SUn) on the side furthest from the negative wire NL (downstream side).

[0039] The negative electrode wire NL is grounded to the metal housing of the power supply system 1 via the ground wire GL. The ground wire GL is connected to a current sensor 50, a third switch 60, and a limiting resistor 70. When the third switch 60 is turned ON (closed), the ground wire GL becomes conductive. The positions of the current sensor 50, the third switch 60, and the limiting resistor 70 can be arbitrary, as long as they are arranged in series.

[0040] The power supply system 1 and the electrical circuit including the load are equipped with a leakage current detector 200. When a leakage current (ground fault) occurs in the electrical circuit, the leakage current detector 200 outputs a leakage current signal to the control device 100.

[0041] Figure 4 illustrates the closed circuit formed when a leakage current occurs in the battery circuit module M. Figures 4(A) and (B) show a state where a leakage current (ground fault) occurs on the negative side of the battery circuit module Mn-2. The third switch 60 is turned ON. Then, the GD21 of each drive circuit SU is used to drive the battery circuit module Mn closest to the negative terminal line NL (SW11 is OFF and SW12 is ON), and the other battery circuit modules M (M1 to Mn-1) are set to pass-through (SW11 is ON and SW12 is OFF). As shown by the dashed line in Figure 4(A), a closed circuit is formed connecting the ground point of the ground line GL and the leakage current point (ground fault point) of the battery circuit module Mn-2. Therefore, the current sensor 50 detects the current and the current value changes. Next, when battery circuit module Mn-1 is in the driven state and the other battery circuit modules M (M1 to Mn-2, Mn) are in the bypass state, a closed circuit is similarly formed, the current is detected by the current sensor 50, and the current value changes.

[0042] When battery circuit module Mn-2 is in the driven state and the other battery circuit modules M (M1~Mn-3, Mn-1, Mn) are in the bypass state, as shown in Figure 4(B), a closed circuit passing through the current sensor 50 is not formed, and no current is detected by the current sensor 50 (the current value does not change from zero). Similarly, when one of the battery circuit modules M (M1~Mn-3) on the positive electrode PL side (upstream side) of battery circuit module Mn-2 is in the driven state and the other battery circuit modules M are in the bypass state, a closed circuit passing through the current sensor 50 is not formed, no current is detected by the current sensor 50, and the current value does not change.

[0043] Therefore, by sequentially switching the battery circuit module Mn on the negative electrode side NL (downstream side) to the battery circuit module M on the positive electrode side PL, it is possible to identify that a leakage current is occurring in the battery circuit module M when the current value of the current sensor 50 does not change (when the current value does not change from zero).

[0044] Figure 5 illustrates the closed circuit formed when a leakage current occurs in the battery circuit module M. Figures 5(A) and (B) show a state where a leakage current (ground fault) occurs on the positive side of the battery circuit module Mn-2. The third switch 60 is turned ON. Then, all battery circuit modules M are put into a through state by the GD21 of each drive circuit SU. As shown by the dashed line in Figure 5(A), a closed circuit is formed connecting the ground point of the ground line GL and the leakage current point (ground fault point) of the battery circuit module Mn-2. Therefore, the current sensor 50 detects a current corresponding to the voltage (potential) at the leakage current point. If the battery circuit module Mn closest to the negative electrode line NL is put into a driven state, and the other battery circuit modules M (M1 to Mn-1) are kept in a through state, a closed circuit including the driven battery circuit module Mn is formed as shown by the dashed line in Figure 5(B). Therefore, the current value detected by the current sensor 50 changes depending on the voltage of the driven battery circuit module Mn. Next, when battery circuit module Mn-1 is in the driven state and the other battery circuit modules M (M1 to Mn-2, Mn) are in the bypass state, a closed circuit is similarly formed, and the current value detected by the current sensor 50 changes.

[0045] Since the leakage point is on the positive terminal side of battery circuit module Mn-2, even if battery circuit module Mn-2 is driven and the other battery circuit modules M (M1~Mn-3, Mn-1, Mn) are bypassed, the voltage of battery circuit module Mn-2 is not applied to the closed circuit, and the current value detected by the current sensor 50 does not change. The same is true if one of the battery circuit modules M (M1~Mn-3) on the positive terminal PL side (upstream side) of battery circuit module Mn-2 is driven and the other battery circuit modules M are bypassed.

[0046] Therefore, by sequentially switching the battery circuit module Mn on the negative electrode side NL (downstream side) to the battery circuit module M on the positive electrode side PL, it is possible to identify that a leakage current is occurring in the battery circuit module M when the current value does not change as measured by the current sensor 50.

[0047] Figure 6 is a flowchart showing an example of the processing in the leakage current diagnosis mode performed by the control device 100. This flowchart is executed when a leakage current is detected by the leakage current detector 200, or during the initial check when the power supply system 1 is started up.

[0048] When a ground fault is detected by the ground fault detector 200, or when this process is initiated during an initial check, first, in step 10 (hereinafter, steps are abbreviated as "S"), the relay 40 is shut off and the third switch 60 is turned ON (closed), then the process proceeds to S11, where m is set to n. Subsequently, in S12, the battery circuit module Mm (when S12 is processed for the first time, m=n, so the battery circuit module Mn) is put into a driving state, and the other battery circuit modules M are put into a bypass state, before proceeding to S13.

[0049] In S13, it is determined whether the current value detected by the current sensor 50 has changed. If the current value has changed, S13 is affirmed and the process proceeds to S14. In S14, m is set to m-1 and the process proceeds to S15. In S15, it is determined whether m is 0 or not. If m is not 0 (m≠0), S15 is denied and the process returns to S12. If m is 0 (m=0), S15 is affirmed and the process ends.

[0050] In S12, following S15, the battery circuit module Mm (if it was negatively determined in the initial S15, then m=n-1, so the battery circuit module Mn-1) is put into the driving state, and the other battery circuit modules M are put into the bypass state, before proceeding to S13.

[0051] In S13, if there is no change in the current value, it is determined to be negative and the process proceeds to S16. In S16, it is determined that there is a leakage current in the battery circuit module Mm, and the process ends. For example, if the battery circuit module Mn-2 is in the driven state in S12, and it is determined to be negative in S13, it is determined that there is a leakage current in the battery circuit module Mn-2.

[0052] According to this embodiment, when the control device 100 starts processing in the leakage current diagnosis mode, the relay 40 is shut off and the third switch 60 is turned ON. Then, the battery circuit modules M that are in the driving state are sequentially switched from the battery circuit module M (Mn) closest to the negative electrode wire NL side to the battery circuit module M on the positive electrode wire PL side (other battery circuit modules M are left in a bypass state), and it is determined that a battery circuit module M in the driving state has a leakage current when there is no change in the current value detected by the current sensor 50. As a result, if a leakage current occurs in the battery string St, the battery circuit module M in which the leakage current is occurring can be identified.

[0053] (modified version) Figure 7 is a flowchart showing the processing of the leakage current diagnosis mode executed by the control device 100 in a modified example. This flowchart is also executed when a leakage current is detected by the leakage current detector 200 or during the initial check of the power supply system 1. In S20, similar to S10, the relay 40 is shut off and the third switch 60 is turned ON (closed). In the following S21, m is set to 1. In S22, the battery circuit module Mm (when S22 is processed for the first time, m=1, so battery circuit module M1) is put into a driving state, and the other battery circuit modules M are put into a bypass state before proceeding to S23.

[0054] In S23, it is determined whether the current value detected by the current sensor 50 has changed. If the current value has not changed, S23 is rejected and the process proceeds to S24. In S24, m is set to m+1 and the process proceeds to S25. In S25, it is determined whether m is greater than or equal to n. If m is not greater than n (m≦n), S25 is rejected and the process returns to S22. If m is greater than n (m>n), S25 is rejected and the process ends.

[0055] In S22, following S25, the battery circuit module Mm (if it was negatively determined in the initial S25, then m=2, so battery circuit module M2) is put into the drive state, and the other battery circuit modules M are put into the bypass state, before proceeding to S23.

[0056] If the current value detected by the current sensor 50 changes and a positive determination is made in S23, the process proceeds to S26. In S26, it is determined that a leakage current has occurred in the battery circuit module Mm-1, and the process is terminated. For example, if the battery circuit module Mn-1 is in the operating state in S22 and a positive determination is made in S23, it is determined that a leakage current has occurred in the battery circuit module Mn-2.

[0057] According to this modified version, when the control device 100 starts processing in the leakage current diagnosis mode, the relay 40 is shut off and the third switch 60 is turned ON. Then, the battery circuit modules M are sequentially switched from the battery circuit module M (M1) closest to the positive electrode PL side to the battery circuit module M on the negative electrode NL side (other battery circuit modules M are left in a bypass state), and when there is a change in the current value detected by the current sensor 50, it is determined that the battery circuit module M that was previously in the driven state has a leakage current. This makes it possible to identify the battery circuit module M where the leakage current is occurring if a leakage current is occurring in the battery string St. However, in this modified version, if a leakage current is occurring in the battery circuit module Mn, the battery circuit module M where the leakage current is occurring cannot be identified. In this case, it is preferable to use it in combination with the above embodiment.

[0058] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0059] 1 Power supply system, 11 First switching element (SW), 12 Second switching element (SW), 21 Gate driver (GD), 22 Delay circuit, 25 Positive terminal, 26 Negative terminal, 40 Relay, 50 Current sensor, 60 Third switch, 70 Limiting resistor, 100 Control device, 200 Leakage current detector, B Battery, Cg Cartridge, GL Ground wire, M Battery circuit module, NL Negative wire, OT1, OT2 Output terminals, PL Positive wire, St Battery string, SU Drive circuit, SUB Power circuit.

Claims

1. A battery circuit module including a battery, a first switch connected in parallel to the battery, a second switch connected in series to the battery, and a first output terminal and a second output terminal to which the voltage of the battery is applied when the first switch is OFF and the second switch is ON. A battery string formed by connecting multiple battery circuit modules in series, A control device for controlling the aforementioned battery string, A ground wire that connects the negative terminal wire of the aforementioned battery string, The ground line is provided with a current sensor, a third switch, and a limiting resistor, The control device is The device is switchable between a drive state in which the first switch is OFF and the second switch is ON, and a pass-through state in which the first switch is ON and the second switch is OFF. A power supply system configured to, in leakage current diagnosis mode, turn on the third switch, switch one of the battery circuit modules to the driven state and the other battery circuit modules to the bypass state, sequentially switch the battery circuit modules in the driven state, and determine which battery circuit module is leaking current based on the current value detected by the current sensor.

2. The control device is In the leakage current diagnosis mode, the battery circuit module in the driving state is sequentially switched from the battery circuit module on the negative terminal side to the battery circuit module on the positive terminal side of the battery string. The power supply system according to claim 1, which determines that the battery circuit module in the operating state is leaking current when the current value does not change.

3. The control device is In the leakage current diagnosis mode, the battery circuit module in the driving state is sequentially switched from the battery circuit module on the positive terminal side of the battery string to the battery circuit module on the negative terminal side. The power supply system according to claim 1, wherein when the current value changes, it is determined that the battery circuit module that was in the previously driven state is leaking current.

4. The aforementioned battery string is connected to a load, The control device is The power supply system according to any one of claims 1 to 3, wherein the connection between the battery string and the load is disconnected when the leakage current diagnostic mode is started.

5. The control device is The power supply system according to claim 4, wherein when a leakage current is detected in the electrical circuit including the load, the leakage current diagnostic mode is started.

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