Power supply device

Abstract

A power supply device (10) is included in a vehicle system (100) comprising a first power supply unit (90), a second power supply unit (91), a conductive path (80) provided between the first power supply unit (90) and the second power supply unit (91), and a load (70) electrically connected to the conductive path (80). The power supply device (10) has: a first switch unit (81) that is provided in a first conductive path (80E), of the conductive path (80), between the first power supply unit (90) and the load (70); and a control unit (83) that controls the first switch unit (81). After switching the first switch unit (81) to the OFF state, the control unit (83) causes the first switch unit (81) to return to the ON state when a first return condition is satisfied.

Description

power supply device

[0001] The present disclosure relates to a power supply device.

[0002] The power supply system of Patent Document 1 includes a main battery and a sub-battery, and operates to switch the power supply source to the load from the main battery to the sub-battery when the power supply from the main battery is interrupted. In the power supply system of Patent Document 1, a body diode is provided in a switch between the sub-battery and the load, and when power from the main battery is interrupted, power is supplied to the load via the body diode even when the switch is off, so the power supply is not interrupted.

[0003] Japanese Patent Application Laid-Open No. 2020-182318

[0004] Another approach is to quickly detect the location of the fault and instantly shut off the conduction path. This approach requires the installation of a fault detection circuit to detect the location of the fault. However, there is a concern that the installation of a fault detection circuit could cause the fault detection circuit to malfunction due to noise, resulting in the switch being accidentally switched off.

[0005] The present disclosure has been made in light of the above-mentioned circumstances, and aims to provide a power supply device that is less likely to malfunction.

[0006] The power supply device of the present disclosure is a power supply device included in a vehicle system having: a first power supply unit; a second power supply unit; a conductive path provided between the first power supply unit and the second power supply unit; and a load electrically connected to the conductive path, and includes: a first switch unit provided in a first conductive path between the first power supply unit and the load; and a control unit that controls the first switch unit, wherein the control unit switches the first switch unit to an off state and then returns the first switch unit to an on state when a first return condition is satisfied.

[0007] According to the present disclosure, it is possible to make the power supply device less susceptible to malfunction.

[0008] FIG. 1 is a circuit diagram schematically showing the configuration of a vehicle system according to a first embodiment and a second embodiment. FIG. 2 is a block diagram showing an example of the configuration of a first shutoff circuit and a second shutoff circuit according to the first embodiment and the second embodiment. FIG. 3 is a flowchart showing an example of control in the power supply device according to the first embodiment. FIG. 4 is a flowchart showing an example of control in the power supply device according to the second embodiment. FIG. 5 is a circuit diagram schematically showing the configuration of a vehicle system according to a third embodiment. FIG. 6 is a block diagram showing an example of the configuration of a first shutoff circuit and a second shutoff circuit according to the third embodiment. FIG. 7 is a flowchart showing an example of control in the power supply device according to the third embodiment. FIG. 8 is a circuit diagram schematically showing the configuration of a vehicle system according to another embodiment. FIG. 9 is a circuit diagram schematically showing the configuration of another vehicle system according to another embodiment.

[0009] [Description of Embodiments of the Present Disclosure] In the following, embodiments of the present disclosure are listed and illustrated.

[0010] (1) A power supply device included in a vehicle system including: a first power supply unit; a second power supply unit; a conductive path provided between the first power supply unit and the second power supply unit; and a load electrically connected to the conductive path, the power supply device further including: a first switch unit provided in a first conductive path between the first power supply unit and the load; and a control unit that controls the first switch unit, wherein the control unit switches the first switch unit to an off state and then returns the first switch unit to an on state when a first return condition is satisfied.

[0011] For example, if the control unit switches the first switch unit to the OFF state based on external noise, the probability that the control unit will immediately and repeatedly switch the first switch unit to the OFF state due to external noise is not high. Therefore, according to the configuration of (1), even if the control unit switches the first switch unit to the OFF state by mistake, by returning the first switch unit to the ON state when the first return condition is satisfied, it is possible to recover even if the first switch unit is switched to the OFF state due to a malfunction of the control unit 83.

[0012] (2) The power supply device according to (1), further comprising a second switch unit provided in a second conduction path between the second power supply unit and the load, wherein the control unit switches the first switch unit to an off state when both the first switch unit and the second switch unit are in an on state, switches the second switch unit to an off state when both the first switch unit and the second switch unit are in an on state, and further switches the first switch unit to an on state when the first return condition is satisfied after switching the first switch unit to an off state.

[0013] In the power supply device of (2), when the first power supply unit is configured as the main power supply, it is possible to prevent the power supply from the first power supply unit from being interrupted due to a malfunction of the control unit.

[0014] (3) The power supply device described in (2), wherein the control unit switches the second switch unit to an off state when both the first switch unit and the second switch unit are in an on state, and then returns the second switch unit to an on state when a second return condition is satisfied.

[0015] The power supply device (3) can also prevent the power supply from the second power supply unit from being interrupted due to a malfunction of the control unit.

[0016] (4) The power supply device according to any one of (1) to (3), wherein the control unit has a first shutoff circuit and a restoration instruction unit, wherein the first shutoff circuit switches the first switch unit to an off state when it is determined that the first power supply unit or the first switch unit is in an abnormal state, and maintains the off state of the first switch unit, and the restoration instruction unit outputs a restoration instruction signal when it is determined that the first restoration condition is satisfied, and the first shutoff circuit restores the first switch unit to an on state when it receives the restoration instruction signal.

[0017] The power supply device of (4) can be provided with a recovery instruction unit that determines whether the first recovery condition is satisfied, separately from the first shutoff circuit, which is a conventional configuration that switches the first switch unit to the off state when the first power supply unit or the first switch unit is in an abnormal state. This makes it easy to build a configuration that uses the conventional configuration (first shutoff circuit) while adding a function (recovery instruction unit) that determines whether the first recovery condition is satisfied.

[0018] (5) The power supply device according to (1), wherein the first return condition is a condition that is met every time a second time shorter than the first time elapses during a first time period from when the control unit switches the first switch unit to an off state, and the control unit returns the first switch unit to an on state every time the second time elapses until the first time period elapses.

[0019] If the malfunction of the control unit is caused by external noise, the probability that the control unit will malfunction again immediately due to external noise is not high. Therefore, the power supply device of (5) can recover from the malfunction caused by noise by the control unit returning the first switch unit to the on state every time the second time period elapses while the first time period elapses.

[0020] (6) The power supply device according to (1), wherein an electrical path between the first power supply unit and the first switch unit in the first conductive path is a first power supply side conductive path, an electrical path between the load and the first switch unit in the first conductive path is a first load side conductive path, the first restoration condition includes a condition that a difference between a voltage of the first power supply side conductive path and a voltage of the first load side conductive path is equal to or less than a difference threshold, or the voltage of the first power supply side conductive path is greater than a ground fault threshold that is smaller than a normal voltage, and the control unit restores the first switch unit to an on state when a difference between a voltage of the first power supply side conductive path and a voltage of the first load side conductive path is equal to or less than the difference threshold, or the voltage of the first power supply side conductive path is greater than the ground fault threshold.

[0021] The power supply device of (6) utilizes the voltage in the conductive path, thereby making it easier for the control unit to perform the determination operation in a shorter time.

[0022] (7) The power supply device according to (1), wherein the first restoration condition includes a condition that the temperature of the first switch unit is equal to or lower than a temperature threshold, and the control unit restores the first switch unit to an on state when the temperature of the first switch unit is equal to or lower than the temperature threshold.

[0023] The power supply device (7) is configured to return the first switch unit to the on state based on the temperature of the first switch unit, making it possible to control the first switch unit to return to the on state more easily than when detecting the voltage.

[0024] (8) The power supply device described in (6), wherein the control unit switches the first switch unit to an off state based on at least one of the voltage in the first power supply side conductive path, the current flowing in the first power supply side conductive path, the temperature in the first power supply unit, or the temperature in the first switch unit.

[0025] The power supply device (8) can switch the first switch unit to the off state while taking into consideration the voltage and current in the first power supply side conduction path, the temperature of the first power supply unit, and the temperature of the first switch unit, thereby enabling more precise control to protect the vehicle system.

[0026] 1 is a system mounted on a vehicle. Vehicle system 100 includes a first power supply unit 90, a second power supply unit 91, a conductive path 80, a load 70, and a power supply device 10. Vehicle system 100 supplies power based on first power supply unit 90 and second power supply unit 91 to load 70 via conductive path 80.

[0027] The first power supply unit 90 is, for example, a battery pack formed by combining a plurality of unit cells, such as lithium ion batteries or nickel-metal hydride batteries, in series. The second power supply unit 91 can be, for example, a lead-acid battery or the same type of unit cells as those in the first power supply unit 90. The output voltage of the second power supply unit 91 is equal to the output voltage of the first power supply unit 90.

[0028] The conductive path 80 is provided between the first power supply unit 90 and the second power supply unit 91. The load 70 is electrically connected to the conductive path 80. The electrical path of the conductive path 80 between the first power supply unit 90 and the load 70 is a first conductive path 80E. The electrical path of the conductive path 80 between the second power supply unit 91 and the load 70 is a second conductive path 80F.

[0029] In the present disclosure, "electrically connected" preferably refers to a configuration in which the connection targets are connected in a mutually conductive state (a state in which a current can flow) so that the potentials of both connection targets are equal. However, this configuration is not limited to this. For example, "electrically connected" may also refer to a configuration in which the connection targets are connected in a state in which the two connection targets can be electrically connected with an electrical component interposed between them.

[0030] The load 70 is, for example, an ECU (Electronic Control Unit) of an electric brake device, an ECU of a shift-by-wire device, an ECU of a door lock device, a display device, an ECU of an airbag device, a DCM (Data Communication Module), and the like.

[0031] [Configuration of Power Supply Device] Power supply device 10 is included in vehicle system 100. Power supply device 10 has a first switch unit 81, a second switch unit 82, and a control unit 83.

[0032] The first switch unit 81 is provided in a first conduction path 80E between the first power supply unit 90 and the load 70. The first switch unit 81 uses, for example, a single switching element such as a field effect transistor (FET). The conduction path 80 between the first switch unit 81 and the first power supply unit 90 is a first power supply side conduction path 80A. The conduction path 80 between the first switch unit 81 and the load 70 is a first load side conduction path 80B. In other words, the first switch unit 81 is provided between the first power supply side conduction path 80A and the first load side conduction path 80B. The anode of the body diode of the first switch unit 81 is connected to the first power supply side conduction path 80A, and the cathode of the body diode of the first switch unit 81 is connected to the first load side conduction path 80B. The first switch section 81 switches between an on state in which current flows in both directions between the first power supply side conductive path 80A and the first load side conductive path 80B via the first switch section 81, and an off state in which current is blocked from flowing from the first load side conductive path 80B to the first power supply side conductive path 80A.

[0033] The second switch unit 82 is provided on a conduction path 80 (second conduction path 80F) between the second power supply unit 91 and the load 70. The second switch unit 82 uses, for example, a single switching element such as an FET. The conduction path 80 between the second switch unit 82 and the second power supply unit 91 is a second power-supply-side conduction path 80C. The conduction path 80 between the second switch unit 82 and the load 70 is a second load-side conduction path 80D. In other words, the second switch unit 82 is provided between the second power-supply-side conduction path 80C and the second load-side conduction path 80D. The anode of the body diode of the second switch unit 82 is connected to the second power-supply-side conduction path 80C, and the cathode of the body diode of the second switch unit 82 is connected to the second load-side conduction path 80D. The second switch section 82 switches between an on state in which current flows in both directions between the second power supply side conductive path 80C and the second load side conductive path 80D via the second switch section 82, and an off state in which current flowing from the second load side conductive path 80D to the second power supply side conductive path 80C is blocked.

[0034] The control unit 83 has a function of controlling the first switch unit 81 and the second switch unit 82. The control unit 83 has a recovery instruction unit 83C, a first shutoff circuit 83A, and a second shutoff circuit 83B.

[0035] The restoration instruction unit 83C is configured, for example, by an MCU (Micro Controller Unit). The restoration instruction unit 83C is configured to output a restoration instruction signal Re to the first shutoff circuit 83A and the second shutoff circuit 83B when it determines that a first restoration condition or a second restoration condition is satisfied. The first restoration condition is a condition for restoring the first switch unit 81 to the ON state. The second restoration condition is a condition for restoring the second switch unit 82 to the ON state. The first restoration condition and the second restoration condition are satisfied every time a second time, which is shorter than the first time, elapses during a first time period from when the control unit 83 switches the first switch unit 81 to the OFF state. The first time period is a time period determined from the time when the shutoff instruction signal Cu is input from the first shutoff circuit 83A or the second shutoff circuit 83B while the vehicle equipped with the vehicle system 100 is running. The second time period corresponds to a cycle in which the restoration instruction unit 83C periodically executes a process for determining whether the first power supply unit 90 and the second power supply unit 91 are in an abnormal state.

[0036] The first shutoff circuit 83A is configured by a hardware circuit including, for example, a subtraction circuit S, a first comparator C1, a second comparator C2, an OR circuit Lc, and a latch circuit La, as shown in FIG. 2.

[0037] A known differential amplifier circuit, for example, is used for the subtraction circuit S. A signal V1 (hereinafter also simply referred to as signal V1) capable of identifying the potential of the first power supply side conductive path 80A is input from a first potential detection unit 87A to the subtraction circuit S. A signal V2 (hereinafter also simply referred to as signal V2) capable of identifying the potentials of the first load side conductive path 80B and the second load side conductive path 80D is input from a second potential detection unit 87B to the subtraction circuit S. The subtraction circuit S calculates the difference between the signal V1 and the signal V2 and outputs a difference signal Di indicating this difference.

[0038] The first comparator C1 is configured as a known comparator. A differential signal Di and a differential threshold ThP are input to the first comparator C1. For example, the differential threshold ThP is set to a maximum allowable value for the potential difference between the signal V1 and the signal V2. The first comparator C1 compares the magnitude of the differential signal Di with the magnitude of the differential threshold ThP. When the differential signal Di exceeds the differential threshold ThP, the first comparator C1 outputs a first ground fault signal Gf1 indicating that the first power supply unit 90 is in a ground fault state (abnormal state).

[0039] The first comparator C1 does not output the first ground fault signal Gf1 when the differential signal Di is equal to or less than the differential threshold value ThP. For example, if a ground fault occurs in the first power supply unit 90, the potential (signal V1) of the first power supply side conductive path 80A becomes smaller than the potential (signal V2) of the first load side conductive path 80B. In other words, the first comparator C1 detects that a ground fault in the first power supply unit 90 reduces the potential (signal V1) of the first power supply side conductive path 80A, and the difference between the potential (signal V1) of the first load side conductive path 80B and the potential (signal V2) of the first load side conductive path 80B becomes larger than the differential threshold value ThP.

[0040] The second comparator C2, like the first comparator C1, is configured as a known comparator. The second comparator C2 receives the signal V1 and a ground fault threshold ThG. The ground fault threshold ThG is set, for example, to a value indicating a voltage lower than the output voltage of the first power supply unit 90 in a normal state. The second comparator C2 compares the magnitude of the signal V1 with the ground fault threshold ThG. When the signal V1 is lower than the ground fault threshold ThG, the second comparator C2 outputs a second ground fault signal Gf2 indicating that the first power supply unit 90 is in a ground fault state (abnormal state).

[0041] The second comparator C2 does not output the second ground fault signal Gf2 when the signal V1 is equal to or greater than the ground fault threshold value ThG. For example, if a ground fault occurs in the first power supply unit 90, the potential (signal V1) of the first power supply side conductive path 80A changes to a magnitude close to the reference potential (ground potential). In other words, the second comparator C2 detects that a ground fault in the first power supply unit 90 causes the potential (signal V1) of the first power supply side conductive path 80A to decrease and become smaller than the ground fault threshold value ThG, which is smaller than the output voltage of the first power supply unit 90 in a normal state.

[0042] The OR circuit Lc is configured to receive a first ground fault signal Gf1 and a second ground fault signal Gf2. When at least one of the first ground fault signal Gf1 and the second ground fault signal Gf2 is input, the OR circuit Lc outputs a shutoff instruction signal Cu. When neither the first ground fault signal Gf1 nor the second ground fault signal Gf2 is input, the OR circuit Lc does not output the shutoff instruction signal Cu.

[0043] A shut-off instruction signal Cu and a restoration instruction signal Re are input to the latch circuit La. When the vehicle equipped with the vehicle system 100 is running, the latch circuit La outputs a conduction signal On to the first switch unit 81 to turn it on. When the vehicle equipped with the vehicle system 100 is running and the vehicle is running, the latch circuit La outputs a shut-off signal Off to the first switch unit 81 upon receiving the shut-off instruction signal Cu from the OR circuit Lc.

[0044] Once the latch circuit La outputs the shutdown signal Off while the vehicle is running, it continues to output the shutdown signal Off regardless of whether the shutdown instruction signal Cu is input. In other words, the first shutdown circuit 83A of the control unit 83 switches the first switch unit 81 to the OFF state when it determines that the first power supply unit 90 is in an abnormal state, and maintains the OFF state of the first switch unit 81. The first switch unit 81 is switched to the OFF state by the shutdown signal Off. If the latch circuit La receives a restoration instruction signal Re from the restoration instruction unit 83C while outputting the shutdown signal Off, it outputs a conduction signal On to the first switch unit 81 instead of the shutdown signal Off. The first switch unit 81, which is in the OFF state, returns to the ON state when the conduction signal On is input. Thus, the latch circuit La of the first shutdown circuit 83A restores the first switch unit 81 to the ON state upon receiving the restoration instruction signal Re.

[0045] The first shutoff circuit 83A determines that the first power supply unit 90 is in a ground fault state (abnormal state) using the first comparator C1 or the second comparator C2. Then, the first comparator C1 outputs a first ground fault signal Gf1 to the latch circuit La, or the second comparator C2 outputs a second ground fault signal Gf2 to the latch circuit La. When the first ground fault signal Gf1 or the second ground fault signal Gf2 is input, the OR circuit Lc outputs a shutoff instruction signal Cu to the latch circuit La. When the shutoff instruction signal Cu is input, the latch circuit La outputs a shutoff signal Off to the first switch unit 81, switching the first switch unit 81 to the OFF state. When the latch circuit La receives a restore instruction signal Re, the latch circuit La outputs a conduction signal On to the first switch unit 81, restoring the first switch unit 81 to the ON state.

[0046] Second shutoff circuit 83B has a configuration similar to that of first shutoff circuit 83A, and is configured by a hardware circuit including a subtraction circuit S, a first comparator C1, a second comparator C2, an OR circuit Lc, and a latch circuit La. Detailed description of the configuration similar to that of first shutoff circuit 83A will be omitted.

[0047] The subtraction circuit S is configured to receive a signal V3 (hereinafter simply referred to as signal V3) capable of identifying the potential of the second power supply side conductive path 80C from the third potential detection unit 87C and a signal V2 from the second potential detection unit 87B. The subtraction circuit S calculates the difference between the signal V3 and the signal V2 and outputs a difference signal Di indicating this difference.

[0048] The first comparator C1 of the second shutoff circuit 83B is configured to receive the differential signal Di and a differential threshold ThP. The differential threshold ThP used in the second shutoff circuit 83B may be the same as or different from the differential threshold ThP used in the first shutoff circuit 83A. The first comparator C1 compares the magnitude of the differential signal Di with the magnitude of the differential threshold ThP. When the differential signal Di exceeds the differential threshold ThP, the first comparator C1 outputs a first ground fault signal Gf1 indicating that the second power supply unit 91 is in a ground fault state (abnormal state).

[0049] The first comparator C1 of the second shutoff circuit 83B does not output the first ground fault signal Gf1 when the differential signal Di is equal to or less than the differential threshold value ThP. For example, if a ground fault occurs in the second power supply unit 91, the potential (signal V3) of the second power supply side conductive path 80C becomes smaller than the potential (signal V2) of the second load side conductive path 80D. In other words, the first comparator C1 of the second shutoff circuit 83B detects that the ground fault in the second power supply unit 91 reduces the potential (signal V3) of the second power supply side conductive path 80C, and the difference between the potential (signal V2) of the second load side conductive path 80D and the potential (signal V3) of the second load side conductive path 80D becomes larger than the differential threshold value ThP.

[0050] The second comparator C2 of the second shutoff circuit 83B is configured to receive the signal V3 and a ground fault threshold ThG. The ground fault threshold ThG used in the second shutoff circuit 83B may be the same as or different from the ground fault threshold ThG used in the first shutoff circuit 83A. The second comparator C2 compares the magnitude of the signal V3 with the ground fault threshold ThG. If the signal V3 is smaller than the ground fault threshold ThG, the second comparator C2 outputs a second ground fault signal Gf2 indicating that the second power supply unit 91 is in a ground fault state (abnormal state).

[0051] The second comparator C2 of the second shutoff circuit 83B does not output the second ground fault signal Gf2 when the signal V3 is equal to or greater than the ground fault threshold ThG. For example, if a ground fault occurs in the second power supply unit 91, the potential (signal V3) of the second power supply side conductive path 80C changes to a magnitude close to the reference potential (ground potential). In other words, the second comparator C2 of the second shutoff circuit 83B detects that the ground fault in the second power supply unit 91 causes the potential (signal V3) of the second power supply side conductive path 80C to decrease and become smaller than the ground fault threshold ThG, which is smaller than the output voltage of the second power supply unit 91 in a normal state.

[0052] The OR circuit Lc of the second shutoff circuit 83B outputs a shutoff instruction signal Cu when at least one of the first ground fault signal Gf1 and the second ground fault signal Gf2 is input, and does not output the shutoff instruction signal Cu when neither the first ground fault signal Gf1 nor the second ground fault signal Gf2 is input.

[0053] When the vehicle equipped with vehicle system 100 is traveling, latch circuit La of second shutoff circuit 83B outputs a conduction signal On to turn on second switch unit 82. When the vehicle equipped with vehicle system 100 is traveling, latch circuit La outputs a shutoff signal Off to second switch unit 82 upon receiving a shutoff instruction signal Cu from OR circuit Lc of second shutoff circuit 83B.

[0054] Once the latch circuit La of the second shutoff circuit 83B outputs a shutoff signal Off while the vehicle is running, it continues to output the shutoff signal Off regardless of whether a shutoff instruction signal Cu is input. The second switch unit 82 is switched to the off state by the shutoff signal Off. If a restoration instruction signal Re is input from the restoration instruction unit 83C while the latch circuit La is outputting the shutoff signal Off, it outputs a conduction signal On to the second switch unit 82 instead of the shutoff signal Off. When the conduction signal On is input, the second switch unit 82, which is in the off state, returns to the on state.

[0055] The second shutoff circuit 83B determines that the second power supply unit 91 is in a ground fault state (abnormal state) using the first comparator C1 or the second comparator C2. Then, the first comparator C1 outputs a first ground fault signal Gf1 to the latch circuit La, or the second comparator C2 outputs a second ground fault signal Gf2 to the latch circuit La. When either the first ground fault signal Gf1 or the second ground fault signal Gf2 is input, the OR circuit Lc outputs a shutoff instruction signal Cu to the latch circuit La. When the shutoff instruction signal Cu is input, the latch circuit La outputs a shutoff signal Off to the second switch unit 82, switching the second switch unit 82 to the off state. When the latch circuit La receives a restore instruction signal Re, the latch circuit La outputs a conduction signal On to the second switch unit 82, restoring the second switch unit 82 to the on state.

[0056] The first potential detection unit 87A, the second potential detection unit 87B, and the third potential detection unit 87C are configured, for example, as known potential detection circuits. As shown in FIG. 1 , the first potential detection unit 87A is provided in the first power supply side conductive path 80A. The second potential detection unit 87B is provided in the first load side conductive path 80B. The second potential detection unit 87B may also be provided in the second load side conductive path 80D. The third potential detection unit 87C is provided in the second power supply side conductive path 80C.

[0057] [Example of Operation of Power Supply Device] Next, an example of operation of the power supply device 10 will be described with reference to Fig. 3. For example, when a vehicle equipped with the vehicle system 100 is running, the first switch unit 81 and the second switch unit 82 are controlled by the control unit 83 to be maintained in an on state. The power supply device 10 periodically monitors the signals V1, V2, and V3 while the vehicle is running. Periodic monitoring corresponds to, for example, repeatedly executing the flowchart of Fig. 3 at predetermined intervals.

[0058] In step S1, if the shutdown signal Off is not output from first shutdown circuit 83A or second shutdown circuit 83B (No in step S1), the process shown in Fig. 3 is terminated and the process shown in Fig. 3 is executed again. Here, the time required after the process shown in Fig. 3 is terminated until the process shown in Fig. 3 is executed again is the second time.

[0059] In step S1, if the first shutoff circuit 83A or the second shutoff circuit 83B outputs the shutoff signal Off (Yes in step S1), the process proceeds to step S2. Then, the first shutoff circuit 83A switches the first switch unit 81 from the ON state to the OFF state, or the second shutoff circuit 83B switches the second switch unit 82 from the ON state to the OFF state. In other words, when the vehicle is traveling and both the first switch unit 81 and the second switch unit 82 are in the ON state, the first switch unit 81 or the second switch unit 82 is switched to the OFF state. In step S1, it is only determined whether the shutoff signal Off has been output from the first shutoff circuit 83A or the second shutoff circuit 83B, and it is not determined whether the first shutoff circuit 83A or the second shutoff circuit 83B is malfunctioning due to external noise. Therefore, it is possible that the shutoff signal Off will be output from the first shutoff circuit 83A or the second shutoff circuit 83B due to external noise, causing the process to proceed to step S2.

[0060] Next, the process proceeds to step S3, where a counter included in the restoration instruction unit 83C is incremented by 1. For example, the counter is configured as a part of the RAM included in the restoration instruction unit 83C, and is set to 0 in advance.

[0061] Next, in step S4, the restoration instruction unit 83C determines whether the first time has elapsed and whether the counter has reached a predetermined value. Step S4 is a step for eliminating the possibility of malfunction of the first shutoff circuit 83A or the second shutoff circuit 83B due to external noise. For example, the restoration instruction unit 83C is configured to receive a shutoff instruction signal Cu (see FIG. 2 ), and the input of the shutoff instruction signal Cu triggers the start of measurement of the first time. For example, the first time may be measured using a timer function of the restoration instruction unit 83C. The first time is longer than the second time required to repeatedly execute the process shown in FIG. 3 . For example, the first time may be set to a length that allows the process shown in FIG. 3 to be executed multiple times before the first time elapses. The predetermined value to be compared with the counter value is, for example, stored as a constant in a memory or the like of the restoration instruction unit 83C.

[0062] In step S4, if the restoration instruction unit 83C determines that the first time has elapsed or that the counter has not reached the predetermined value (No in step S4), the process proceeds to step S7. Then, the first switch unit 81 or the second switch unit 82, which is in the OFF state, is restored to the ON state. Specifically, when the first switch unit 81 is in the OFF state, the restoration instruction unit 83C outputs a restoration instruction signal Re to the first shutoff circuit 83A. As a result, the first shutoff circuit 83A outputs a conduction signal On to the first switch unit 81, restoring the first switch unit 81 to the ON state.

[0063] Furthermore, when the second switch unit 82 is in the OFF state, the restoration instruction unit 83C outputs a restoration instruction signal Re to the second shutoff circuit 83B. As a result, the second shutoff circuit 83B outputs a conduction signal On to the second switch unit 82, causing the second switch unit 82 to return to the ON state. Then, the process shown in Fig. 3 is terminated, and the process shown in Fig. 3 is executed again. For example, the control unit 83 executes the process shown in Fig. 3 every time the second time elapses until the first time elapses, thereby restoring the first switch unit 81 to the ON state.

[0064] A No in step S4 indicates that the first time has elapsed and therefore it is determined that the first power supply unit 90 or the second power supply unit 91 is in a normal state. Therefore, when the No in step S4 is obtained after the first time has elapsed, measurement of the first time using the timer function of the recovery instruction unit 83C is terminated. Furthermore, a No in step S4 indicates that the counter has not reached a predetermined value and therefore the first switch unit 81 or the second switch unit 82, which is in the OFF state, is returned to the ON state, and it is again determined whether the first shutoff circuit 83A or the second shutoff circuit 83B will output the shutoff signal Off.

[0065] In step S4, if the recovery instruction unit 83C determines that the first time period has not elapsed and the counter has reached a predetermined value (Yes in step S4), the process proceeds to step S5, where the recovery instruction unit 83C determines that a ground fault has occurred in the first power supply unit 90 or the second power supply unit 91. Then, the process proceeds to step S6, where the first shutoff circuit 83A maintains the first switch unit 81 in the OFF state, or the second shutoff circuit 83B maintains the second switch unit 82 in the OFF state. Then, the process shown in FIG. 3 ends.

[0066] A Yes in step S4 means that the first shutoff circuit 83A or the second shutoff circuit 83B did not malfunction due to external noise, but that a ground fault actually occurred in the first power supply unit 90 or the second power supply unit 91. Thus, if the first power supply unit 90 or the second power supply unit 91 enters a ground fault state (abnormal state) while the first switch unit 81 and the second switch unit 82 are in the on state, the control unit 83 switches the first switch unit 81 or the second switch unit 82 to the off state in step S2. The control unit 83 then maintains this state.

[0067] The first and second return conditions are conditions that are met every time a second time, which is shorter than the first time, elapses during the first time period from when the control unit 83 switched the first switch unit 81 to the OFF state in step S1 (every time the process shown in FIG. 3 is executed). In other words, the control unit 83 switches the first switch unit 81 (second switch unit 82) to the OFF state in step S1 when the vehicle is running and the first switch unit 81 and the second switch unit 82 are in the ON state. Thereafter, the control unit 83 returns the first switch unit 81 (second switch unit 82) to the ON state every time the process shown in FIG. 3 is executed (i.e., when the first return condition (second return condition) is satisfied).

[0068] Next, an example of the effect of this configuration will be described. The power supply device 10 is included in a vehicle system 100 that includes a first power supply unit 90, a second power supply unit 91, a conductive path 80 provided between the first power supply unit 90 and the second power supply unit 91, and a load 70 electrically connected to the conductive path 80. The power supply device 10 includes a first switch unit 81 provided in a first conductive path 80E of the conductive path 80 between the first power supply unit 90 and the load 70, and a control unit 83 that controls the first switch unit 81. After switching the first switch unit 81 to the OFF state, the control unit 83 returns the first switch unit 81 to the ON state when a first return condition is satisfied.

[0069] For example, if the control unit 83 switches the first switch unit 81 to the OFF state due to external noise, the probability that the control unit 83 will immediately and repeatedly switch the first switch unit 81 to the OFF state due to external noise is not high. Therefore, with this configuration, even if the control unit 83 switches the first switch unit 81 to the OFF state, the first switch unit 81 is returned to the ON state when the first return condition is satisfied. This makes it possible to recover even if the first switch unit 81 is switched to the OFF state due to a malfunction of the control unit 83.

[0070] The power supply device 10 has a second switch unit 82 provided in the second conduction path 80F between the second power supply unit 91 and the load 70. The control unit 83 switches the first switch unit 81 to the OFF state when both the first switch unit 81 and the second switch unit 82 are in the ON state. The control unit 83 also switches the second switch unit 82 to the OFF state when both the first switch unit 81 and the second switch unit 82 are in the ON state. After switching the first switch unit 81 to the OFF state, the control unit 83 further switches the first switch unit 81 back to the ON state when a first return condition is satisfied. With this configuration, when the first power supply unit 90 is configured as the main power supply, it is possible to prevent the power supply from the first power supply unit 90 from being interrupted due to a malfunction of the control unit 83.

[0071] The control unit 83 switches the second switch unit 82 to the OFF state when both the first switch unit 81 and the second switch unit 82 are ON, and then returns the second switch unit 82 to the ON state when a second return condition is satisfied. With this configuration, it is possible to prevent the power supply from the second power supply unit 91 from being interrupted due to a malfunction of the control unit 83.

[0072] The control unit 83 includes a first shutoff circuit 83A and a restoration instruction unit 83C. The first shutoff circuit 83A switches the first switch unit 81 to the OFF state and maintains the OFF state when it determines that the first power supply unit 90 is in an abnormal state. The restoration instruction unit 83C outputs a restoration instruction signal Re when it determines that the first restoration condition is satisfied. The first shutoff circuit 83A restores the first switch unit 81 to the ON state upon receiving the restoration instruction signal Re. This configuration allows the restoration instruction unit 83C, which determines whether the first restoration condition is satisfied, to be provided separately from the first shutoff circuit 83A, which has a conventional configuration that switches the first switch unit 81 to the OFF state when the first power supply unit 90 is in an abnormal state. In other words, it is easy to build a configuration that utilizes the conventional configuration (first shutoff circuit 83A) while adding a function (restore instruction unit 83C) that determines whether the first restoration condition is satisfied.

[0073] The first recovery condition is a condition that is met every time a second time, which is shorter than the first time, elapses during the first time period from when the control unit 83 switches the first switch unit 81 to the off state. The control unit 83 recovers the first switch unit 81 to the on state every time the second time period elapses until the first time period elapses. If the operation of the control unit 83 is caused by external noise, the probability that the control unit 83 will immediately and repeatedly malfunction due to the external noise is not high. Therefore, with this configuration, the control unit 83 can recover from the malfunction caused by noise by recovering the first switch unit 81 to the on state every time the second time period elapses during the first time period.

[0074] 1 has a power supply device 20 that is different from that of the first embodiment in the operation of a control unit 83. The configuration of the vehicle system 200 is the same as that of the vehicle system 100, and detailed description thereof will be omitted.

[0075] [Example of Operation of Power Supply Device] An example of operation of the power supply device 20 will be described with reference to Fig. 4. For example, when a vehicle equipped with the vehicle system 200 is running, the first switch unit 81 and the second switch unit 82 are controlled by the control unit 83 to be maintained in an on state. While the vehicle is running, the power supply device 20 periodically monitors the potential (signal V1) of the first power supply side conductive path 80A, the potential (signal V2) of the first load side conductive path 80B and the second load side conductive path 80D, and the potential (V3) of the second power supply side conductive path 80C. "Periodic monitoring" corresponds to repeatedly executing the flowchart of Fig. 4 at predetermined intervals.

[0076] In step S11, if the shutdown signal Off is not output from first shutdown circuit 83A or second shutdown circuit 83B (No in step S11), the process shown in Fig. 4 is terminated and the process shown in Fig. 4 is executed again. Here, the time required after the process shown in Fig. 4 is terminated until the process shown in Fig. 4 is executed again is the second time.

[0077] In step S11, if the shutdown signal Off is output from the first shutdown circuit 83A or the second shutdown circuit 83B (Yes in step S11), the process proceeds to step S12. Then, the first shutdown circuit 83A switches the first switch unit 81 from the ON state to the OFF state, or the second shutdown circuit 83B switches the second switch unit 82 from the ON state to the OFF state. Then, the process proceeds to step S13, where 1 is added to a counter included in the recovery instruction unit 83C. For example, the counter is preset to 0.

[0078] Next, the process proceeds to step S14, where the first interrupting circuit 83A determines whether the difference between the potential (signal V1) of the first power supply side conductive path 80A and the potential (signal V2) of the first load side conductive path 80B is greater than the difference threshold value ThP, and whether the potential (signal V1) of the first power supply side conductive path 80A is equal to or less than the ground fault threshold value ThG.

[0079] In step S14, if the first interrupting circuit 83A determines that the difference between the potential (signal V1) of the first power supply side conductive path 80A and the potential (signal V2) of the first load side conductive path 80B is greater than the difference threshold value ThP and that the potential (signal V1) of the first power supply side conductive path 80A is equal to or less than the ground fault threshold value ThG (Yes in step S14), the process proceeds to step S15. In step S15, the control unit 83 determines that the first power supply side conductive path 80A has a ground fault (i.e., a ground fault has occurred in the first power supply unit 90). In step S20, the first interrupting circuit 83A maintains the first switch unit 81 in the off state, and the process shown in FIG. 4 ends. In this way, when the first power supply unit 90 experiences a ground fault (abnormal state) while the first switch unit 81 and the second switch unit 82 are in the on state, the control unit 83 switches the first switch unit 81 to the off state in step S12 and then maintains this state.

[0080] In step S14, if the first interrupting circuit 83A determines that the difference between the potential (signal V1) of the first power supply side conductive path 80A and the potential (signal V2) of the first load side conductive path 80B is equal to or smaller than the difference threshold value ThP, or that the potential (signal V1) of the first power supply side conductive path 80A is greater than the ground fault threshold value ThG (No in step S14), the process proceeds to step S16. No in step S14 means that it has been determined that the first power supply unit 90 is not in a ground fault state.

[0081] The process proceeds to step S16. The second interrupting circuit 83B then determines whether the difference between the potential of the second power supply side conductive path 80C (signal V3) and the potential of the second load side conductive path 80D (signal V2) is greater than the difference threshold value ThP, and whether the potential of the second power supply side conductive path 80C (signal V3) is equal to or less than the ground fault threshold value ThG.

[0082] In step S16, if the second interrupting circuit 83B determines that the difference between the potential (signal V3) of the second power source side conductive path 80C and the potential (signal V2) of the second load side conductive path 80D is greater than the difference threshold value ThP and that the potential (signal V3) of the second power source side conductive path 80C is equal to or less than the ground fault threshold value ThG (Yes in step S16), the process proceeds to step S17. In step S17, the control unit 83 determines that the second power source side conductive path 80C has a ground fault (i.e., a ground fault has occurred in the second power supply unit 91). Then, the process proceeds to step S20, in which the second interrupting circuit 83B maintains the second switch unit 82 in the off state, and the process shown in FIG. 4 ends. In this way, when the second power supply unit 91 experiences a ground fault (abnormal state) while the first switch unit 81 and the second switch unit 82 are in the on state, the control unit 83 switches the second switch unit 82 to the off state in step S12 and then maintains this state.

[0083] In step S16, if the second interrupting circuit 83B determines that the difference between the potential (signal V3) of the second power supply side conductive path 80C and the potential (signal V2) of the second load side conductive path 80D is equal to or smaller than the difference threshold value ThP, or that the potential (signal V3) of the second power supply side conductive path 80C is greater than the ground fault threshold value ThG (No in step S16), the process proceeds to step S18. No in step S16 means that it has been determined that the second power supply unit 91 is not in a ground fault state.

[0084] When the process proceeds to step S18, the recovery instruction unit 83C determines whether the first time has elapsed and whether the counter has reached a predetermined value. The first time is a time determined from the time when the first shutoff circuit 83A or the second shutoff circuit 83B outputs the shutoff signal Off for the first time while the vehicle equipped with the vehicle system 200 is traveling. The first time is a time longer than the second time required to repeatedly execute the process shown in FIG. 4. For example, the first time can be set to a length that allows the process shown in FIG. 4 to be executed multiple times before the first time has elapsed.

[0085] In step S18, if the restoration instruction unit 83C determines that the first time has elapsed or that the counter has not reached the predetermined value (No in step S18), the process proceeds to step S21. In step S21, the first switch unit 81 or the second switch unit 82, which is currently in the OFF state, is restored to the ON state. Specifically, when the first switch unit 81 is in the OFF state, the restoration instruction unit 83C outputs a restoration instruction signal Re to the first shutoff circuit 83A. As a result, the first shutoff circuit 83A outputs a conduction signal On to the first switch unit 81, restoring the first switch unit 81 to the ON state. Furthermore, when the second switch unit 82 is in the OFF state, the restoration instruction unit 83C outputs a restoration instruction signal Re to the second shutoff circuit 83B. As a result, the second shutoff circuit 83B outputs a conduction signal On to the second switch unit 82, restoring the second switch unit 82 to the ON state. The process shown in FIG. 4 then ends, and the process shown in FIG. 4 is executed again.

[0086] In step S18, if the recovery instruction unit 83C determines that the first time period has not elapsed and that the counter has reached a predetermined value (Yes in step S18), the process proceeds to step S19. In step S19, the recovery instruction unit 83C determines that a ground fault has occurred in the first power supply side conductive path 80A, or that a ground fault has occurred in the second power supply side conductive path 80C, or that the first breaking circuit 83A has failed, or that the second breaking circuit 83B has failed, and the process proceeds to step S20. Then, the process shown in FIG. 4 ends.

[0087] The condition that the first time period has elapsed or the counter has not reached a predetermined value (No in step S18) is a first return condition for returning the first switch unit 81 to the ON state, and a second return condition for returning the second switch unit 82 to the ON state. Furthermore, step S18 is executed after a No determination is made in step S14. Therefore, the first return condition includes a condition that the difference between the potential (signal V1) of the first power supply side conductive path 80A and the potential (signal V2) of the first load side conductive path 80B is equal to or smaller than the difference threshold value ThP, or that the potential (signal V1) of the first power supply side conductive path 80A is greater than the ground fault threshold value ThG (No in step S14). In other words, the control unit 83 returns the first switch unit 81 to the on state when the difference between the voltage (signal V1) of the first power supply side conductive path 80A and the voltage (signal V2) of the first load side conductive path 80B is less than the differential threshold value ThP, or when the voltage (signal V1) of the first power supply side conductive path 80A is greater than the ground fault threshold value ThG (No in step S14).

[0088] Furthermore, step S18 is executed after a determination of No in step S16. Therefore, the second return condition includes a condition that the difference between the potential of the second power supply side conductive path 80C (signal V3) and the potential of the second load side conductive path 80D (signal V2) is equal to or smaller than the difference threshold value ThP, or that the potential of the second power supply side conductive path 80C (signal V3) is greater than the ground fault threshold value ThG (No in step S16). In other words, the control unit 83 returns the second switch unit 82 to the on state when the difference between the potential of the second power supply side conductive path 80C (signal V3) and the potential of the second load side conductive path 80D (signal V2) is equal to or smaller than the difference threshold value ThP, or when the potential of the second power supply side conductive path 80C (signal V3) is greater than the ground fault threshold value ThG (No in step S16).

[0089] The electrical path of first conductive path 80E between first power supply unit 90 and first switch unit 81 is first power supply side conductive path 80A, and the electrical path of first conductive path 80E between load 70 and first switch unit 81 is first load side conductive path 80B. The first recovery condition includes a condition that the difference between the voltage (signal V1) of first power supply side conductive path 80A and the voltage (signal V2) of first load side conductive path 80B is equal to or smaller than difference threshold value ThP, or that the voltage (signal V1) of first power supply side conductive path 80A is greater than ground fault threshold value ThG that is smaller than the normal voltage of first power supply unit 90. The control unit 83 returns the first switch unit 81 to the on state when the difference between the voltage (signal V1) of the first power supply side conductive path 80A and the voltage (signal V2) of the first load side conductive path 80B is equal to or smaller than the difference threshold value ThP, or when the voltage (signal V1) of the first power supply side conductive path 80A is greater than the ground fault threshold value ThG. With this configuration, by utilizing the voltage in the conductive path 80, the determination operation by the control unit 83 can be performed more quickly.

[0090] 5 differs from the first and second embodiments in that it has a first temperature detection unit 93A and a second temperature detection unit 93B, in the configurations of a first shutoff circuit 183A and a second shutoff circuit 183B, and in the operation of a control unit 83 of a power supply device 30, but is otherwise common to the first and second embodiments. In the following description, detailed description of the same configuration as that of vehicle system 100 of the first embodiment will be omitted.

[0091] The first temperature detector 93A and the second temperature detector 93B may be, for example, a thermistor or a resistance temperature detector. The first temperature detector 93A and the second temperature detector 93B are configured to output a temperature signal indicating the temperature around the location where they are installed. The first temperature detector 93A is disposed near the first switch unit 81. The first temperature detector 93A outputs a signal T1 (hereinafter simply referred to as signal T1) that can identify the temperature of the first switch unit 81. The second temperature detector 93B is disposed near the second switch unit 82. The second temperature detector 93B outputs a signal T2 (hereinafter simply referred to as signal T2) that can identify the temperature of the second switch unit 82.

[0092] As shown in FIG. 6 , the first shutoff circuit 183A is configured, for example, by a hardware circuit including a comparator C and a latch circuit La. The comparator C is configured as a known comparator. The comparator C is configured to receive a signal T1 and a temperature threshold ThT. For example, the temperature threshold ThT is set to a value corresponding to a temperature higher than the temperature that would be reached if the maximum possible current were to flow when the first switch unit 81 or the second switch unit 82 is in the on state. The comparator C compares the magnitude of the signal T1 with the temperature threshold ThT. If the signal T1 is greater than the temperature threshold ThT, the comparator C outputs an overheat signal Oh, indicating that the first switch unit 81 has exceeded the possible temperature and is in an overheated state (abnormal state).

[0093] Comparator C does not output overheat signal Oh when signal T1 is equal to or lower than temperature threshold value ThT. For example, if a ground fault occurs in first power supply unit 90, a large current flows into first power supply unit 90 via first switch unit 81. In other words, comparator C detects that a ground fault occurs in first power supply unit 90, causing a large current to flow through first switch unit 81, resulting in an overheated state (abnormal state) of first switch unit 81.

[0094] An overheat signal Oh and a recovery instruction signal Re are input to the latch circuit La. When the vehicle equipped with the vehicle system 300 is running, the latch circuit La outputs a conduction signal On to the first switch unit 81 to turn it on. When the overheat signal Oh is input from the comparator C while the vehicle equipped with the vehicle system 300 is running, the latch circuit La outputs a cutoff signal Off to the first switch unit 81.

[0095] Once the latch circuit La outputs the shutdown signal Off while the vehicle is running, it continues to output the shutdown signal Off regardless of whether the overheat signal Oh is input. The first switch unit 81 is switched to the OFF state by the shutdown signal Off. If the latch circuit La receives a restoration instruction signal Re from the restoration instruction unit 83C while outputting the shutdown signal Off, it outputs a conduction signal On to the first switch unit 81 instead of the shutdown signal Off. When the conduction signal On is input, the first switch unit 81, which is in the OFF state, returns to the ON state. In this way, the first shutdown circuit 183A can control the first switch unit 81 to switch to the OFF state when it determines that the first switch unit 81 has exceeded an expected temperature and is in an overheated state (abnormal state).

[0096] Second shutoff circuit 183B has a configuration similar to that of first shutoff circuit 183A, and is formed of a hardware circuit including a comparator C and a latch circuit La. Detailed description of the configuration similar to that of first shutoff circuit 183A will be omitted.

[0097] The comparator C of the second shutoff circuit 183B is configured to receive the signal T2 and a temperature threshold value ThT. The temperature threshold value ThT used in the second shutoff circuit 183B may be the same as or different from the temperature threshold value ThT used in the first shutoff circuit 183A. The comparator C compares the magnitude of the signal T2 with the temperature threshold value ThT. If the signal T2 is greater than the temperature threshold value ThT, the comparator C outputs an overheat signal Oh, which indicates that the second switch unit 82 has exceeded an assumed temperature and is in an overheated state (abnormal state).

[0098] Comparator C of second shutoff circuit 183B does not output overheat signal Oh when signal T2 is equal to or lower than temperature threshold value ThT. For example, if second power supply unit 91 experiences a ground fault, a large current flows into second power supply unit 91 via second switch unit 82. In other words, comparator C of second shutoff circuit 183B detects that a ground fault in second power supply unit 91 has caused a large current to flow through second switch unit 82, causing second switch unit 82 to become overheated (in an abnormal state).

[0099] The overheat signal Oh and the restoration instruction signal Re are input to the latch circuit La of the second shutdown circuit 183B. When the vehicle equipped with the vehicle system 300 is running, the latch circuit La outputs a conduction signal On to the second switch unit 82 to turn it on. When the overheat signal Oh is input from the comparator C while the vehicle equipped with the vehicle system 300 is running, the latch circuit La outputs a shutdown signal Off to the second switch unit 82.

[0100] Once the latch circuit La of the second shutoff circuit 183B outputs the shutoff signal Off, it continues to output the shutoff signal Off regardless of whether the overheat signal Oh is input. The second switch unit 82 is switched to the OFF state by the shutoff signal Off. If the latch circuit La receives a restoration instruction signal Re from the restoration instruction unit 83C while outputting the shutoff signal Off, it outputs a conduction signal On to the second switch unit 82 instead of the shutoff signal Off. When the conduction signal On is input, the second switch unit 82, which is in the OFF state, returns to the ON state. In this way, when the second shutoff circuit 183B determines that the second switch unit 82 is in an overheated state (abnormal state) exceeding an anticipated temperature, it can control the second switch unit 82 to switch to the OFF state.

[0101] [Example of Operation of Power Supply Device] An example of operation of the power supply device 30 will be described with reference to Fig. 7. For example, when a vehicle equipped with the vehicle system 300 is running, the first switch unit 81 and the second switch unit 82 are controlled by the control unit 83 to be maintained in an on state. The power supply device 30 periodically monitors the temperatures of the first switch unit 81 and the second switch unit 82 while the vehicle is running. Periodic monitoring corresponds to repeatedly executing the flowchart of Fig. 7 at predetermined intervals.

[0102] In step S31, if the shutdown signal Off is not output from first shutdown circuit 183A or second shutdown circuit 183B (No in step S31), the process shown in FIG. 7 is ended, and the process shown in FIG. 7 is executed again.

[0103] In step S31, if the shutdown signal Off is output from first shutdown circuit 183A or second shutdown circuit 183B (Yes in step S31), the process proceeds to step S32. Then, first shutdown circuit 183A switches first switch unit 81 from the ON state to the OFF state, or second shutdown circuit 183B switches second switch unit 82 from the ON state to the OFF state. Then, the process proceeds to step S33, and 1 is added to a counter included in recovery instruction unit 83C. For example, the counter is preset to 0.

[0104] Next, in step S34, the restoration instruction unit 83C determines whether the temperature (signal T1) of the first switch unit 81 and the temperature (signal T2) of the second switch unit 82 are equal to or lower than the temperature threshold value ThT. If the restoration instruction unit 83C determines in step S34 that the temperature (signal T1) of the first switch unit 81 or the temperature (signal T2) of the second switch unit 82 is greater than the temperature threshold value ThT (No in step S34), the restoration instruction unit 83C proceeds to step S37. Then, the first switch unit 81 or the second switch unit 82 is maintained in the OFF state, and the processing shown in FIG. 7 is terminated. At this time, the first switch unit 81 or the second switch unit 82 is in an overheated state (abnormal state) exceeding an expected temperature. In this way, when the first switch unit 81 or the second switch unit 82 is in the on state and the first switch unit 81 or the second switch unit 82 becomes overheated (abnormal state) beyond the expected temperature, the control unit 83 switches the first switch unit 81 or the second switch unit 82 to the off state in step 32 and then maintains this state.

[0105] In step S34, if the control unit 83 determines that the temperature (signal T1) of the first switch unit 81 and the temperature (signal T2) of the second switch unit 82 are equal to or lower than the temperature threshold value ThT (Yes in step S34), the process proceeds to step S35. Yes in step S34 means that the temperatures of the first switch unit 81 and the second switch unit 82 are within a presumable temperature range and are determined to be in a normal state.

[0106] When the process proceeds to step S35, the recovery instruction unit 83C determines whether the first time has elapsed and whether the counter has reached a predetermined value. The first time is a time determined starting from the first shutoff signal Off being output from the first shutoff circuit 183A or the second shutoff circuit 183B while the vehicle equipped with the vehicle system 300 is running. For example, the recovery instruction unit 83C is configured to receive an overheat signal Oh (see FIG. 6 ), and the input of the overheat signal Oh triggers the start of measurement of the first time. For example, the first time can be measured using a timer function of the recovery instruction unit 83C. The first time is longer than the second time required to repeatedly execute the process shown in FIG. 7 . For example, the first time can be set to a length that allows the process shown in FIG. 7 to be executed multiple times before the first time elapses.

[0107] In step S35, if the restoration instruction unit 83C determines that the first time has elapsed or that the counter has not reached the predetermined value (No in step S35), the process proceeds to step S38. In step S38, the control unit 83 restores the first switch unit 81 or the second switch unit 82, which is currently in the OFF state, to the ON state. Specifically, when the first switch unit 81 is in the OFF state, the restoration instruction unit 83C outputs a restoration instruction signal Re to the first shutoff circuit 183A. This causes the first shutoff circuit 183A to output a conduction signal On to the first switch unit 81, restoring the first switch unit 81 to the ON state. In other words, after switching the first switch unit 81 to the OFF state in step S32, the control unit 83 restores the first switch unit 81 to the ON state when the temperature (signal T1) of the first switch unit 81 is equal to or lower than the temperature threshold value ThT (Yes in step S34).

[0108] Furthermore, when second switch unit 82 is in the OFF state, recovery instruction signal Re is output from recovery instruction unit 83C to second shutoff circuit 183B. As a result, second shutoff circuit 183B outputs conduction signal On to second switch unit 82, causing second switch unit 82 to return to the ON state. In other words, after switching second switch unit 82 to the OFF state in step S32, control unit 83 returns second switch unit 82 to the ON state when the temperature (signal T2) of second switch unit 82 is equal to or lower than temperature threshold value ThT (Yes in step S34). Then, the processing shown in FIG. 7 is terminated, and the processing shown in FIG. 7 is executed again.

[0109] In step S35, if the recovery instruction unit 83C determines that the first time period has not elapsed and the counter has reached a predetermined value (Yes in step S35), the process proceeds to step S36. Then, it is determined that the first switch unit 81 or the second switch unit 82 has failed due to overheating, and the process proceeds to step S37, after which the process shown in FIG. 7 ends.

[0110] The condition that the first time period has elapsed or the counter has not reached a predetermined value (No in step S35) is a first return condition for returning the first switch unit 81 to the ON state, and a second return condition for returning the second switch unit 82 to the ON state. Furthermore, step S35 is executed after a Yes determination is made in step S34. Therefore, the condition that the temperature of the first switch unit 81 is equal to or lower than the temperature threshold value ThT (Yes in step S34) is included in the first return condition. Furthermore, the condition that the temperature of the second switch unit 82 is equal to or lower than the temperature threshold value ThT (Yes in step S34) is included in the second return condition.

[0111] The first return condition includes a condition that the temperature (signal T1) of the first switch unit 81 is equal to or lower than the temperature threshold value ThT, and the control unit 83 returns the first switch unit 81 to the ON state when the temperature (signal T1) of the first switch unit 81 is equal to or lower than the temperature threshold value ThT. According to this configuration, the first switch unit 81 is returned to the ON state based on the temperature (signal T1) of the first switch unit 81, so that it is possible to control the first switch unit 81 to return to the ON state more easily than when detecting the voltage.

[0112] <Other Embodiments> The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0113] Unlike the first, second, and third embodiments, a vehicle system 400 shown in FIG. 8 may further include a first current detection unit 94A that outputs a signal A1 that can identify the direction and magnitude of the current flowing through the first power source side conductive path 80A, and a second current detection unit 94B that outputs a signal A2 that can identify the direction and magnitude of the current flowing through the second power source side conductive path 80C. The first current detection unit 94A outputs the signal A1 that can identify the direction and magnitude of the current flowing through the first power source side conductive path 80A. The second current detection unit 94B outputs the signal A2 that can identify the direction and magnitude of the current flowing through the second power source side conductive path 80C. The first current detection unit 94A and the second current detection unit 94B may be configured as known current detection circuits using, for example, a current transformer or a shunt resistor.

[0114] For example, the first shutoff circuit 283A of the power supply device 40 determines whether the direction of the current in the signal A1 is toward the first power supply unit 90 and whether the magnitude of the current in the signal A1 is greater than a current threshold. If the first shutoff circuit 283A determines that the direction of the current in the signal A1 is toward the first power supply unit 90 or that the magnitude of the current in the signal A1 is greater than the current threshold, the first shutoff circuit 283A switches the first switch unit 81 to the OFF state. Furthermore, the second shutoff circuit 283B of the power supply device 40 determines whether the direction of the current in the signal A2 is toward the second power supply unit 91 and whether the magnitude of the current in the signal A2 is greater than the current threshold. If the second shutoff circuit 283B determines that the direction of the current in the signal A2 is toward the second power supply unit 91 or that the magnitude of the current in the signal A2 is greater than the current threshold, the second shutoff circuit 283B switches the second switch unit 82 to the OFF state. Note that in a configuration in which second power supply unit 91 is charged by power supplied from first power supply unit 90 and supplies power to load 70 if first power supply unit 90 fails, the direction of the current in signal A2 is meaningless. For this reason, second shutoff circuit 283B may be configured to determine only whether the magnitude of the current in signal A2 is greater than a current threshold.

[0115] The vehicle system 500 may have a configuration similar to that shown in Fig. 9. Specifically, in addition to the first potential detector 87A, the second potential detector 87B, the third potential detector 87C, the first temperature detector 93A, the second temperature detector 93B, the first current detector 94A, and the second current detector 94B, a third temperature detector 93C and a fourth temperature detector 93D may be further provided. The third temperature detector 93C outputs a signal T3 capable of identifying the temperature of the first power supply unit 90. The fourth temperature detector 93D outputs a signal T4 capable of identifying the temperature of the second power supply unit 91.

[0116] For example, the first shutoff circuit 383A of the control unit 83 of the power supply device 50 may be configured to switch the first switch unit 81 to the OFF state based on at least one of the signal V1 from the first potential detection unit 87A, the signal V2 from the second potential detection unit 87B, the signal A1 from the first current detection unit 94A, the signal T3 from the third temperature detection unit 93C, and the signal T1 from the first temperature detection unit 93A. The second shutoff circuit 383B of the control unit 83 of the power supply device 50 may be configured to switch the second switch unit 82 to the OFF state based on at least one of the signal V3 from the third potential detection unit 87C, the signal V2 from the second potential detection unit 87B, the signal A2 from the second current detection unit 94B, the signal T4 from the fourth temperature detection unit 93D, and the signal T2 from the second temperature detection unit 93B.

[0117] According to this configuration, the first switch unit 81 can be switched to the OFF state in consideration of the voltage (signal V1) and current (signal A1) in the first power supply side conductive path 80A, the temperature (signal T3) of the first power supply unit 90, and the temperature (signal T1) of the first switch unit 81. Therefore, the second switch unit 82 can be switched to the OFF state in consideration of the voltage (signal V3) and current (signal A2) in the second power supply side conductive path 80C, the temperature (signal T4) of the second power supply unit 91, and the temperature (signal T2) of the second switch unit 82, enabling more precise control to protect the vehicle system 500.

[0118] Unlike the first, second, and third embodiments, the restoration instruction unit may be configured with a plurality of hardware circuits other than an MCU. Also, the first shutoff circuit, the second shutoff circuit, and the restoration instruction unit may be configured with a single MCU.

[0119] Unlike the above embodiments, each switch unit may be configured to use a pair of FETs, or a switch may be configured to use a combination of a pair of FETs and a single FET. For example, when a pair of FETs is used in the first switch unit, the body diodes of the FETs are butted together in opposite directions. Specifically, the FETs may be configured to switch between an ON state that allows bidirectional current flow between the first power supply side conductive path and the first load side conductive path via the first switch unit, and an OFF state that blocks current flow between the first load side conductive path and the first power supply side conductive path. Furthermore, when a pair of FETs is used in the second switch unit, the body diodes of the FETs are butted together in opposite directions. Specifically, the FETs may be configured to switch between an ON state that allows bidirectional current flow between the second power supply side conductive path and the second load side conductive path via the second switch unit, and an OFF state that blocks current flow between the second load side conductive path and the second power supply side conductive path.

[0120] DESCRIPTION OF SYMBOLS 10, 20, 30, 40, 50: Power supply device 70: Load 80: Conduction path 80A: First power supply side conduction path (conduction path) 80B: First load side conduction path (conduction path) 80C: Second power supply side conduction path (conduction path) 80D: Second load side conduction path (conduction path) 80E: First conduction path (conduction path) 80F: Second conduction path (conduction path) 81: First switch unit 82: Second switch unit 83: Control unit 83A, 183A, 283A, 383A: First breaking circuit 83B, 183B, 283B, 383B: Second breaking circuit 83C: Recovery instruction unit 87A: First potential detection unit 87B: Second potential detection unit 87C: Third potential detection unit 90 : First power supply unit 91 : Second power supply unit 93A : First temperature detection unit 93B : Second temperature detection unit 93C : Third temperature detection unit 93D : Fourth temperature detection unit 94A : First current detection unit 94B : Second current detection unit 100, 200, 300, 400, 500: Vehicle system A1, A2, T1, T2, T3, T4, V1, V2, V3 : Signal C : Comparator C1 : First comparator C2 : Second comparator Cu : Shutdown instruction signal Di : Differential signal Gf1 : First earth fault signal Gf2 : Second earth fault signal La : Latch circuit Lc : OR circuit Off : Shutdown signal Oh : Overheat signal On : Conduction signal Re : Recovery instruction signal S : Subtraction circuit ThG : Ground fault threshold ThP : Difference threshold ThT : Temperature threshold

Claims

1. A power supply device included in a vehicle system having a first power supply unit, a second power supply unit, a conductive path provided between the first power supply unit and the second power supply unit, and a load electrically connected to the conductive path, the power supply device having a first switch unit provided in a first conductive path between the first power supply unit and the load, and a control unit that controls the first switch unit, wherein the control unit switches the first switch unit to an off state and then returns the first switch unit to an on state when a first return condition is satisfied.

2. The power supply device according to claim 1, further comprising a second switch unit provided in a second conductive path between the second power supply unit and the load among the conductive paths, wherein the control unit switches the first switch unit to an OFF state when both the first switch unit and the second switch unit are in an ON state, switches the second switch unit to an OFF state when both the first switch unit and the second switch unit are in an ON state, and further restores the first switch unit to an ON state when the first return condition is satisfied after switching the first switch unit to the OFF state.

3. The power supply device of claim 2, wherein the control unit switches the second switch unit to an off state when both the first switch unit and the second switch unit are in an on state, and then returns the second switch unit to an on state when a second return condition is satisfied.

4. The power supply device according to any one of claims 1 to 3, wherein the control unit has a first shutoff circuit and a restoration instruction unit, wherein the first shutoff circuit switches the first switch unit to an off state and maintains the off state of the first switch unit when it is determined that the first power supply unit or the first switch unit is in an abnormal state, and the restoration instruction unit outputs a restoration instruction signal when it is determined that the first restoration condition is satisfied, and the first shutoff circuit restores the first switch unit to an on state when it receives the restoration instruction signal.

5. The power supply device of claim 1, wherein the first return condition is a condition that is met every time a second time shorter than the first time elapses during a first time period from when the control unit switches the first switch unit to an off state, and the control unit returns the first switch unit to the on state every time the second time elapses until the first time elapses.

6. The power supply device of claim 1, wherein an electrical path among the first conductive path between the first power supply unit and the first switch unit is a first power supply side conductive path, an electrical path among the first conductive path between the load and the first switch unit is a first load side conductive path, the first return condition includes a condition that a difference between a voltage of the first power supply side conductive path and a voltage of the first load side conductive path is equal to or less than a difference threshold, or the voltage of the first power supply side conductive path is greater than a ground fault threshold which is smaller than a normal voltage, and the control unit returns the first switch unit to an on state when a difference between a voltage of the first power supply side conductive path and a voltage of the first load side conductive path is equal to or less than the difference threshold, or the voltage of the first power supply side conductive path is greater than the ground fault threshold.

7. The power supply device of claim 1, wherein the first recovery condition includes a condition that the temperature of the first switch unit is equal to or lower than a temperature threshold, and the control unit restores the first switch unit to an on state when the temperature of the first switch unit is equal to or lower than the temperature threshold.

8. The power supply device of claim 6, wherein the control unit switches the first switch unit to an off state based on at least one of the voltage in the first power supply side conductive path, the current flowing in the first power supply side conductive path, the temperature in the first power supply unit, or the temperature in the first switch unit.

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