In-vehicle cutoff device

Abstract

An in-vehicle cutoff device (20) is included in an in-vehicle system (1) comprising: a first power supply unit (11); a second power supply unit (12); a power path (13); a first load (14) connected to the power path (13) via a first branch path (16); and a second load (15) connected to the power path (13) via a second branch path (17) on the second power supply unit (12) side relative to the first load (14). The withstand voltage of the first power supply unit (11) is lower than the withstand voltage of the second power supply unit (12). The withstand voltage of the first load (14) is lower than the withstand voltage of the second load (15). The in-vehicle cutoff device (20) has a first switch unit (21) provided in a conductive path between the first load (14) and the second load (15) in the power path (13). The first switch unit (21) switches between an on state in which current is allowed to flow from the second power supply unit (12) side to the first load (14) side and an off state in which the current flowing from the second power supply unit (12) side to the first load (14) side is cut off.

Description

Vehicle-mounted circuit breaker

[0001] The present disclosure relates to an on-vehicle shutoff device.

[0002] Patent Document 1 discloses a power supply system having multiple power systems. Each power system is provided with a power output unit. An inter-system switch is provided between the power systems. The inter-system switch cuts off the connection between the power systems when an overcurrent or low voltage occurs. An intra-system switch is provided on the side of each power output unit from the inter-system switch. An electrical load is provided in each power system. When an overcurrent or low voltage occurs, each intra-system switch cuts off the connection between the power output unit and the electrical load.

[0003] Japanese Patent Application Laid-Open No. 2022-13791

[0004] Patent Document 1 does not describe how to deal with an overvoltage, and there is room for improvement in this regard.

[0005] An object of the present disclosure is to provide a technique that can easily prevent an overvoltage from being applied to a load with a low withstand voltage.

[0006] The on-board circuit breaker of the present disclosure is an on-board circuit breaker included in an on-board system having a first power supply unit, a second power supply unit, a power path provided between the first power supply unit and the second power supply unit, a first load connected to the power path via a first branch path, and a second load connected to the power path via a second branch path on the second power supply unit side of the first load, wherein the withstand voltage of the first power supply unit is lower than the withstand voltage of the second power supply unit, and the withstand voltage of the first load is lower than the withstand voltage of the second load, and the on-board circuit breaker has a first switch unit provided in a conduction path between the first load and the second load on the power path, and the first switch unit switches between an on state that allows current to flow from the second power supply unit side to the first load side and an off state that cuts off current flowing from the second power supply unit side to the first load side.

[0007] The technology according to the present disclosure makes it easy to prevent an overvoltage from being applied to a load with a low withstand voltage.

[0008] FIG. 1 is a configuration diagram of an in-vehicle system including an in-vehicle circuit breaker of a first embodiment. FIG. 2 is an explanatory diagram showing a normal power supply state of the in-vehicle system of the first embodiment. FIG. 3 is an explanatory diagram showing an operation of the in-vehicle system of the first embodiment when an overvoltage occurs in the power path. FIG. 4 is an explanatory diagram showing an operation of the in-vehicle system of the first embodiment when the output voltage of the second power supply unit becomes a low voltage or when the output current of the second power supply unit becomes an overcurrent. FIG. 5 is a configuration diagram of an in-vehicle system including an in-vehicle circuit breaker of a second embodiment. FIG. 6 is an explanatory diagram showing a normal power supply state of the in-vehicle system of the second embodiment. FIG. 7 is an explanatory diagram showing an operation of the in-vehicle system of the second embodiment when an overvoltage occurs in the power path. FIG. 8 is an explanatory diagram showing an operation of the in-vehicle system of the second embodiment when the output voltage of the second power supply unit becomes a low voltage. FIG. 9 is an explanatory diagram showing an operation of the in-vehicle system of the second embodiment when the output current of the second power supply unit becomes an overcurrent. FIG. 10 is an explanatory diagram showing the operation when the output current of the first power supply unit in the in-vehicle system of the second embodiment becomes an overcurrent.

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

[0010] [1] An on-board circuit breaker included in an on-board system having a first power supply unit, a second power supply unit, a power path provided between the first power supply unit and the second power supply unit, a first load connected to the power path via a first branch path, and a second load connected to the power path via a second branch path on the second power supply unit side of the first load, wherein the withstand voltage of the first power supply unit is lower than the withstand voltage of the second power supply unit, and the withstand voltage of the first load is lower than the withstand voltage of the second load, and the on-board circuit breaker has a first switch unit provided in a conduction path between the first load and the second load in the power path, and the first switch unit switches between an on state that allows current to flow from the second power supply unit side to the first load side and an off state that cuts off current flowing from the second power supply unit side to the first load side.

[0011] The above-mentioned vehicle interrupter device can supply power to the first load and the second load from both the first power supply unit and the second power supply unit when the first switch unit is in the on state. Furthermore, the above-mentioned vehicle interrupter device can prevent power from being supplied from the second power supply unit to the first load when the first switch unit is in the off state. Therefore, for example, when the output voltage of the second power supply unit becomes an overvoltage, the above-mentioned vehicle interrupter device can prevent an overvoltage generated by the second power supply unit from being applied to the first load by switching the first switch unit to the off state. In other words, the above-mentioned vehicle interrupter device can easily prevent an overvoltage from being applied to the first load having a low withstand voltage and the first power supply unit having a low withstand voltage. Furthermore, the above-mentioned vehicle interrupter device can supply power to the second load from the second power supply unit even when the first switch unit is in the off state.

[0012] [2] The vehicle-mounted circuit breaking device described in [1], wherein the first power supply unit includes a battery and applies the output voltage of the battery to the power path, and the second power supply unit includes a power supply source and a voltage conversion unit that boosts or lowers the voltage input from the power supply source and outputs it, and applies the output voltage of the voltage conversion unit to the power path.

[0013] On the first power supply side, the battery output voltage is applied to the power path. Therefore, an overvoltage is unlikely to occur on the first power supply side. In contrast, on the second power supply side, the output voltage of the voltage conversion unit is applied to the power path. Therefore, an overvoltage may occur on the second power supply side. With this configuration, an overvoltage is unlikely to be input from the first power supply to the first load. Conversely, an overvoltage may be input from the second power supply to the first load. However, by switching the first switch unit to the off state, an overvoltage can be prevented from being input from the second power supply to the first load. Therefore, the above-described vehicle circuit breaker can more reliably prevent an overvoltage from being applied to the first load having a low withstand voltage and the first power supply side having a low withstand voltage.

[0014] [3] The on-board circuit breaker device according to [2], further comprising a control unit that controls the first switch unit, wherein the control unit switches the first switch unit to an off state when the voltage of the power path becomes an overvoltage while the first switch unit is in an on state.

[0015] When the voltage of the power path becomes an overvoltage, the above-mentioned on-board circuit breaker switches the first switch unit to the off state, thereby preventing an overvoltage from being applied to the first load with a low withstand voltage and the first power supply unit with a low withstand voltage, while supplying power to the second load with a high withstand voltage.

[0016] [4] The on-board circuit breaking device according to [3], further comprising a second switch unit provided on the power path closer to the second power supply unit than the second load, wherein the second switch unit switches between an on state that allows current to flow from the second load side to the second power supply unit side and an off state that blocks current flowing from the second load side to the second power supply unit side, and wherein the control unit switches the first switch unit to the off state when the voltage of the power path becomes an overvoltage while the first switch unit and the second switch unit are in the on state, and switches the second switch unit to the off state while maintaining the first switch unit in the on state when the voltage of the power path becomes an undervoltage.

[0017] When the voltage of the power path becomes an overvoltage, the vehicle circuit breaker switches the first switch unit to an OFF state, thereby preventing an overvoltage from being applied to the first load having a low withstand voltage and the first power supply unit having a low withstand voltage, while supplying power to the second load having a high withstand voltage. Moreover, when the voltage of the power path becomes a low voltage, the vehicle circuit breaker switches the second switch unit to an OFF state while maintaining the first switch unit in an ON state. This allows the vehicle circuit breaker to supply power from the first power supply unit to the first load and the second load, even if a ground fault occurs in the second power supply unit.

[0018] [5] The on-board circuit breaker according to [3] or [4], further comprising a second switch unit provided on the power path closer to the second power supply unit than the second load, wherein the second switch unit switches between an on state that allows current to flow from the first power supply unit side to the second power supply unit side and an off state that blocks current flowing from the first power supply unit side to the second power supply unit side, and wherein the control unit switches the first switch unit to the off state when the voltage of the power path becomes an overvoltage while the first switch unit and the second switch unit are in the on state, and switches the second switch unit to the off state while maintaining the first switch unit in the on state when an overcurrent flows into the second power supply unit.

[0019] When the voltage of the power path becomes an overvoltage, the vehicle circuit breaker switches the first switch unit to the OFF state, thereby preventing an overvoltage from being applied to the first load having a low withstand voltage and the first power supply unit having a low withstand voltage, while supplying power to the second load having a high withstand voltage. Moreover, when an overcurrent flows into the second power supply unit, the vehicle circuit breaker switches the second switch unit to the OFF state while maintaining the first switch unit in the ON state. This allows the vehicle circuit breaker to supply power from the first power supply unit to the first load and the second load even if the second power supply unit has a ground fault.

[0020] [6] The control unit switches the first switch unit to the off state, and then, when a return condition is met, returns the first switch unit to the on state. The vehicle-mounted circuit breaking device described in any one of [3] to [5].

[0021] The above-described on-vehicle cutoff device can restore the first switch unit to the ON state when the restoration condition is met.

[0022] [7] The control unit switches the first switch unit or the second switch unit to the off state, and then, when a return condition is met, returns the first switch unit or the second switch unit that has been switched to the off state to the on state. The vehicle-mounted circuit breaking device described in any one of [3] to [5].

[0023] The above-described on-vehicle cutoff device can restore the switch unit, which has been switched to the OFF state, to the ON state when a restoration condition is met.

[0024] [8] An on-board circuit breaker device according to any one of [4] to [7], further comprising a third switch unit provided on the power path closer to the first power supply unit than the first load, wherein the third switch unit switches between an on state that allows current to flow from the second power supply unit side to the first power supply unit side, and an off state that cuts off current flowing from the second power supply unit side to the first power supply unit side.

[0025] The above-mentioned vehicle-mounted circuit breaker device can supply power from the second power supply unit to the first load and the second load, for example, even if the first power supply unit has a ground fault, by switching the third switch unit to the off state.

[0026] [9] The vehicle-mounted circuit breaker device described in [8], wherein the control unit switches the first switch unit to the off state when the voltage of the power path becomes an overvoltage while the first switch unit, the second switch unit, and the third switch unit are in the on state, and switches the second switch unit and the third switch unit to the off state while maintaining the first switch unit in the on state when the voltage of the power path becomes an undervoltage.

[0027] When the voltage of the power path becomes an overvoltage, the vehicle circuit breaker switches the first switch unit to an OFF state, thereby preventing an overvoltage from being applied to the first load having a low withstand voltage and the first power supply unit having a low withstand voltage, while supplying power to the second load having a high withstand voltage. Moreover, when the voltage of the power path becomes a low voltage, the vehicle circuit breaker switches the second switch unit and the third switch unit to an OFF state while maintaining the first switch unit in an ON state. As a result, the vehicle circuit breaker can supply power to the first and second loads from the second power supply unit when a ground fault occurs in the first power supply unit, and can supply power to the first and second loads from the first power supply unit when a ground fault occurs in the second power supply unit.

[0028]

[10] The control unit switches the first switch unit to the off state when the voltage of the power path becomes an overvoltage while the first switch unit, the second switch unit, and the third switch unit are in the on state, switches the third switch unit to the off state when an overcurrent flows into the first power supply unit, and switches the second switch unit to the off state when an overcurrent flows into the second power supply unit.The vehicle-mounted circuit breaker device described in [8] or [9].

[0029] When the voltage of the power path becomes an overvoltage, the vehicle circuit breaker switches the first switch unit to an OFF state, thereby preventing an overvoltage from being applied to the first load having a low withstand voltage and the first power supply unit having a low withstand voltage, while supplying power to the second load having a high withstand voltage. Moreover, the vehicle circuit breaker switches the third switch unit to an OFF state when an overcurrent flows into the first power supply unit. This allows the vehicle circuit breaker to supply power from the second power supply unit to the first and second loads even when a ground fault occurs in the first power supply unit. Furthermore, the vehicle circuit breaker switches the second switch unit to an OFF state when an overcurrent flows into the second power supply unit. This allows the vehicle circuit breaker to supply power from the first power supply unit to the first and second loads even when a ground fault occurs in the second power supply unit.

[0030] [Details of the embodiment of the present disclosure] 1. First embodiment 1-1. Configuration of in-vehicle system 1 The in-vehicle system 1 of the first embodiment shown in Fig. 1 is a system mounted on a vehicle. The in-vehicle system 1 includes a first power supply unit 11, a second power supply unit 12, and a power path 13. The power path 13 is provided between the first power supply unit 11 and the second power supply unit 12.

[0031] The first power supply unit 11 includes a battery 11A. The battery 11A is, for example, a lithium-ion battery. The first power supply unit 11 applies the output voltage of the battery 11A to the power path 13. The withstand voltage of the first power supply unit 11 is lower than the withstand voltage of the second power supply unit 12 and is also lower than the withstand voltage of the second load 15.

[0032] The second power supply unit 12 has a power supply source 12A and a voltage conversion unit 12B. The power supply source 12A is configured by, for example, a battery or a generator. The voltage conversion unit 12B increases or decreases the voltage input from the power supply source 12A and outputs the increased voltage. The second power supply unit 12 applies the output voltage of the voltage conversion unit 12B to the power path 13.

[0033] The in-vehicle system 1 includes a first load 14 and a second load 15. The withstand voltage of the first load 14 is lower than the withstand voltage of the second load 15. For example, the rated voltage of the first load 14 is lower than the rated voltage of the second load 15. The first load 14 is electrically connected to the power path 13 via a first branch path 16. The second load 15 is electrically connected to the power path 13 via a second branch path 17 on the second power supply unit 12 side of the first load 14.

[0034] The vehicle system 1 includes an in-vehicle circuit breaker 20. The in-vehicle circuit breaker 20 has a first switch unit 21, a second switch unit 22, voltage detection units 31, 32, and 33, current detection units 34 and 35, a control unit 40, and an electrical connection box 41.

[0035] The first switch unit 21 is provided in the conduction path between the first load 14 and the second load 15 in the power path 13. The first switch unit 21 switches between an ON state in which current is allowed to flow from the second power supply unit 12 to the first load 14, and an OFF state in which current is blocked from flowing from the second power supply unit 12 to the first load 14. The first switch unit 21 is configured, for example, by a MOSFET.

[0036] The second switch unit 22 is provided on the power path 13 closer to the second power supply unit 12 than the second load 15. The second switch unit 22 switches between an ON state in which current is allowed to flow from the first power supply unit 11 to the second power supply unit 12, and an OFF state in which current is blocked from flowing from the first power supply unit 11 to the second power supply unit 12. The second switch unit 22 is configured, for example, by a MOSFET.

[0037] The above-mentioned power path 13 includes a first conductive path 13A, a second conductive path 13B, and a third conductive path 13C. The first conductive path 13A is disposed between the first switch unit 21 and the first power supply unit 11. The second conductive path 13B is disposed between the second switch unit 22 and the second power supply unit 12. The third conductive path 13C is disposed between the first switch unit 21 and the second switch unit 22.

[0038] The voltage detection unit 31 detects the voltage of the first conductive path 13A. The voltage detection unit 32 detects the voltage of the second conductive path 13B. The voltage detection unit 33 detects the voltage of the third conductive path 13C. Signals indicating the detection results of the voltage detection units 31, 32, and 33 are input to the control unit 40. The voltage detection units 31, 32, and 33 are configured by, for example, known voltage detection circuits.

[0039] The current detection unit 34 detects the current flowing in the first conductive path 13A. The current detection unit 34 detects the direction of the current flowing in the first conductive path 13A. The current detection unit 35 detects the current flowing in the second conductive path 13B. The current detection unit 35 detects the direction of the current flowing in the second conductive path 13B. Signals indicating the detection results by the current detection units 34, 35 are input to the control unit 40. The current detection units 34, 35 are configured by, for example, known current sensors.

[0040] The control unit 40 may be configured by a microcomputer, a hardware circuit, or a combination of these. The control unit 40 controls the first switch unit 21 and the second switch unit 22.

[0041] The electrical connection box 41 is electrically connected to the first power supply unit 11, the second power supply unit 12, the first load 14, and the second load 15. The electrical connection box 41 houses the first switch unit 21, the second switch unit 22, the voltage detection units 31, 32, and 33, the current detection units 34 and 35, and the control unit 40.

[0042] 1-2. Operation of the In-Vehicle System 1 When a supply start condition is met, the control unit 40 switches the first switch unit 21 and the second switch unit 22 to the ON state. The supply start condition may be, for example, that the start switch of the vehicle is switched to the ON state, or may be another condition. The start switch may be, for example, an ignition switch or a power switch. When the first switch unit 21 and the second switch unit 22 are in the ON state, power is supplied from the first power supply unit 11 and the second power supply unit 12 to the first load 14 and the second load 15, as shown in FIG. 2 .

[0043] The control unit 40 determines whether the voltage of the power path 13 has become an overvoltage when the first switch unit 21 and the second switch unit 22 are in the on state. The control unit 40 determines whether the voltage of the power path 13 has become an overvoltage using the detection result of any one of the voltage detection units 31, 32, and 33. The control unit 40 determines that the voltage of the power path 13 has become an overvoltage when the voltage of the power path 13 exceeds an overvoltage threshold. The control unit 40 determines that the voltage of the power path 13 is not an overvoltage when the voltage of the power path 13 does not exceed the overvoltage threshold. The overvoltage threshold is, for example, a value greater than the withstand voltage of the first load 14, greater than the withstand voltage of the first power supply unit 11, smaller than the withstand voltage of the second load 15, and smaller than the withstand voltage of the second power supply unit 12. The overvoltage threshold is, for example, a value greater than the rated voltage of the first load 14, a value greater than the rated voltage of the first power supply unit 11, a value less than the rated voltage of the second load 15, and a value less than the rated voltage of the second power supply unit 12.

[0044] As described above, on the first power supply unit 11 side, the output voltage of the battery 11A is applied to the power path 13. Therefore, an overvoltage is unlikely to occur on the first power supply unit 11 side. In contrast, on the second power supply unit 12 side, the output voltage of the voltage conversion unit 12B is applied to the power path 13. Therefore, an overvoltage may occur on the second power supply unit 12 side. In other words, if the voltage of the power path 13 becomes an overvoltage, it means that there is a high possibility that the output voltage of the second power supply unit 12 has become an overvoltage. Therefore, when the voltage of the power path 13 becomes an overvoltage, the onboard circuit breaker 20 operates assuming that the output voltage of the second power supply unit 12 has become an overvoltage.

[0045] When the control unit 40 determines that the voltage on the power path 13 has become an overvoltage, it switches the first switch unit 21 to the off state while maintaining the second switch unit 22 in the on state. This prevents an overvoltage from being input from the second power supply unit 12 to the first load 14, as shown in Fig. 3. Furthermore, even when the first switch unit 21 is switched to the off state, power is supplied from the first power supply unit 11 to the first load 14, and power is supplied from the second power supply unit 12 to the second load 15.

[0046] Furthermore, the control unit 40 determines whether the voltage of the power path 13 has become low voltage when the first switch unit 21 and the second switch unit 22 are in the on state. The control unit 40 determines whether the voltage of the power path 13 has become low voltage using the detection result of any one of the voltage detection units 31, 32, and 33. The control unit 40 determines that the voltage of the power path 13 has become low voltage when the voltage of the power path 13 is below a low voltage threshold. The control unit 40 determines that the voltage of the power path 13 is not low voltage when the voltage of the power path 13 is not below the low voltage threshold. The low voltage threshold is a value smaller than the withstand voltage of the first load 14, a value smaller than the withstand voltage of the first power supply unit 11, a value smaller than the rated voltage of the first load 14, and a value smaller than the rated voltage of the first power supply unit 11.

[0047] When the control unit 40 determines that the voltage of the power path 13 has become low, it switches the second switch unit 22 to the off state while maintaining the first switch unit 21 in the on state. As a result, even if the output voltage of the second power supply unit 12 becomes low, as shown in FIG. 4 , power from the first power supply unit 11 is prevented from being supplied to the second power supply unit 12 via the second switch unit 22, and power is supplied from the first power supply unit 11 to the first load 14 and the second load 15.

[0048] Furthermore, the control unit 40 determines whether or not an overcurrent has flowed into the second power supply unit 12 when the first switch unit 21 and the second switch unit 22 are in the on state. The control unit 40 determines whether or not an overcurrent has flowed into the second power supply unit 12 using the detection result of the current detection unit 35. The control unit 40 determines that an overcurrent has flowed into the second power supply unit 12 when it determines that a current has flowed into the second power supply unit 12 and that the current flowing into the second power supply unit 12 exceeds a threshold current.

[0049] When the control unit 40 determines that an overcurrent has flowed into the second power supply unit 12, it switches the second switch unit 22 to the OFF state while maintaining the first switch unit 21 in the ON state. As a result, as shown in Fig. 4, power is prevented from being supplied from the first power supply unit 11 to the second power supply unit 12 via the second switch unit 22, and power is supplied from the first power supply unit 11 to the first load 14 and the second load 15.

[0050] After switching the first switch unit 21 to the OFF state, the control unit 40 returns the first switch unit 21 to the ON state when a first return condition is met. The first return condition may be, for example, that the voltage of the power path 13 becomes equal to or lower than a first return voltage, that a predetermined time has elapsed since the first switch unit 21 was switched to the OFF state, or that a condition is met every time a first time shorter than the second time has elapsed before a second time has elapsed since the first switch unit 21 was switched to the OFF state. The first return voltage may be the same value as the overvoltage threshold value or may be a value smaller than the overvoltage threshold value.

[0051] After switching the second switch unit 22 to the OFF state, the control unit 40 switches the second switch unit 22 back to the ON state when a second return condition is met. The second return condition may be, for example, that the voltage of the power path 13 is equal to or greater than a second return voltage, that the state in which an overcurrent flows into the second power supply unit 12 is resolved, that a predetermined time has elapsed since the first switch unit 21 was switched to the OFF state, or that the condition is met every time a first time period shorter than the second time period has elapsed before the second time period has elapsed since the first switch unit 21 was switched to the OFF state. The second return voltage may be the same value as the low-voltage threshold value or may be a value greater than the low-voltage threshold value.

[0052] 1-3. Effects of the Vehicle Circuit Breaker 20 On the first power supply unit 11 side, the output voltage of the battery 11A is applied to the power path 13. Therefore, an overvoltage is unlikely to occur on the first power supply unit 11 side. In contrast, on the second power supply unit 12 side, the output voltage of the voltage conversion unit 12B is applied to the power path 13. Therefore, an overvoltage may occur on the second power supply unit 12 side. With this configuration, an overvoltage is unlikely to be input from the first power supply unit 11 to the first load 14. Conversely, an overvoltage may be input from the second power supply unit 12 to the first load 14. However, the vehicle circuit breaker 20 can prevent an overvoltage from being input from the second power supply unit 12 to the first load 14 by switching the first switch unit 21 to the OFF state. Moreover, even when the first switch unit 21 is switched to the OFF state, power is supplied from the second power supply unit 12 to the second load 15. Therefore, according to the on-board circuit breaker 20, even if the output voltage of the second power supply unit 12 becomes an overvoltage, it is possible to supply power to the second load 15 having a high withstand voltage while preventing an overvoltage from being applied to the first load 14 having a low withstand voltage and the first power supply unit 11 having a low withstand voltage.

[0053] Furthermore, when the voltage of the power path 13 becomes low, the vehicle circuit breaker 20 switches the second switch unit 22 to the off state while maintaining the first switch unit 21 in the on state. As a result, the vehicle circuit breaker 20 can supply power from the first power supply unit 11 to the first load 14 and the second load 15 even if the second power supply unit 12 has a ground fault.

[0054] Furthermore, when an overcurrent flows into the second power supply unit 12, the vehicle circuit breaker 20 switches the second switch unit 22 to the off state while maintaining the first switch unit 21 in the on state. This allows the vehicle circuit breaker 20 to supply power from the first power supply unit 11 to the first load 14 and the second load 15 even if the second power supply unit 12 has a ground fault.

[0055] The vehicle-mounted circuit breaking device 20 can return the first switch unit 21 to the ON state when a first return condition is satisfied. The vehicle-mounted circuit breaking device 20 can return the second switch unit 22 to the ON state when a second return condition is satisfied.

[0056] 2. Second Embodiment In the second embodiment, a configuration in which a third switch unit is further provided will be described. Note that in the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0057] 2-1. Configuration of the in-vehicle system 201 The in-vehicle system 201 of the second embodiment shown in Fig. 5 is a system mounted on a vehicle. The in-vehicle system 201 includes a first power supply unit 11, a second power supply unit 12, a power path 13, a first load 14, and a second load 15.

[0058] The vehicle system 201 includes an in-vehicle circuit breaker 220. The in-vehicle circuit breaker 220 has a first switch unit 21, a second switch unit 22, a third switch unit 23, voltage detection units 31, 32, and 33, current detection units 34 and 35, a control unit 40, and an electrical connection box 41.

[0059] The third switch unit 23 is provided on the power path 13 closer to the first power supply unit 11 than the first load 14. The third switch unit 23 switches between an ON state, which allows current to flow from the second power supply unit 12 to the first power supply unit 11, and an OFF state, which blocks current from flowing from the second power supply unit 12 to the first power supply unit 11. The third switch unit 23 is configured with, for example, a MOSFET. The first conduction path 13A is provided between the first switch unit 21 and the third switch unit 23.

[0060] 2-2. Operation of the In-Vehicle System 201 When the supply start condition is met, the control unit 40 switches the first switch unit 21, the second switch unit 22, and the third switch unit 23 to the ON state. When the first switch unit 21, the second switch unit 22, and the third switch unit 23 are in the ON state, power is supplied from the first power supply unit 11 and the second power supply unit 12 to the first load 14 and the second load 15, as shown in FIG.

[0061] The control unit 40 determines whether the voltage of the power path 13 has become an overvoltage when the first switch unit 21, the second switch unit 22, and the third switch unit 23 are in the on state. The control unit 40 determines whether the voltage of the power path 13 has become an overvoltage using the detection result of any one of the voltage detection units 31, 32, and 33.

[0062] 7 , when the control unit 40 determines that the voltage of the power path 13 has become an overvoltage, it switches the first switch unit 21 to the OFF state while maintaining the second switch unit 22 and the third switch unit 23 in the ON state. This prevents an overvoltage from being input from the second power supply unit 12 to the first load 14. Furthermore, even when the first switch unit 21 is switched to the OFF state, power is supplied from the first power supply unit 11 to the first load 14, and power is supplied from the second power supply unit 12 to the second load 15.

[0063] Furthermore, the control unit 40 determines whether the voltage of the power path 13 has become low when the first switch unit 21, the second switch unit 22, and the third switch unit 23 are in the on state. The control unit 40 determines whether the voltage of the power path 13 has become low using the detection result of any one of the voltage detection units 31, 32, and 33.

[0064] 8 , when the control unit 40 determines that the voltage of the power path 13 has become low, it switches the second switch unit 22 and the third switch unit 23 to the OFF state while maintaining the first switch unit 21 in the ON state. As a result, even if the output voltage of the second power supply unit 12 is low, power from the first power supply unit 11 is prevented from being supplied to the second power supply unit 12 via the second switch unit 22, and power is supplied from the first power supply unit 11 to the first load 14 and the second load 15. Furthermore, when the output voltage of the first power supply unit 11 is low, power from the second power supply unit 12 is prevented from being supplied to the first power supply unit 11 via the first switch unit 21, and power is supplied from the second power supply unit 12 to the first load 14 and the second load 15.

[0065] Furthermore, the control unit 40 determines whether or not an overcurrent has flowed into the second power supply unit 12 when the first switch unit 21, the second switch unit 22, and the third switch unit 23 are in the on state. The control unit 40 determines whether or not an overcurrent has flowed into the second power supply unit 12 using the detection result of the current detection unit 35. The control unit 40 determines that an overcurrent has flowed into the second power supply unit 12 when it determines that a current has flowed into the second power supply unit 12 and that the current flowing into the second power supply unit 12 exceeds a threshold current.

[0066] When the control unit 40 determines that an overcurrent has flowed into the second power supply unit 12, it switches the second switch unit 22 to the OFF state while maintaining the first switch unit 21 and the third switch unit 23 in the ON state. This prevents power from the first power supply unit 11 from being supplied to the second power supply unit 12 via the second switch unit 22, and power is supplied from the first power supply unit 11 to the first load 14 and the second load 15, as shown in Fig. 9 .

[0067] Furthermore, the control unit 40 determines whether or not an overcurrent has flowed into the first power supply unit 11 when the first switch unit 21, the second switch unit 22, and the third switch unit 23 are in the on state. The control unit 40 determines whether or not an overcurrent has flowed into the first power supply unit 11 using the detection result of the current detection unit 34. The control unit 40 determines that an overcurrent has flowed into the first power supply unit 11 when it determines that a current has flowed into the first power supply unit 11 and that the current flowing into the first power supply unit 11 exceeds a threshold current.

[0068] When the control unit 40 determines that an overcurrent has flowed into the first power supply unit 11, it switches the third switch unit 23 to the OFF state while maintaining the first switch unit 21 and the second switch unit 22 in the ON state. As a result, as shown in Fig. 10 , power from the second power supply unit 12 is prevented from being supplied to the first power supply unit 11 via the third switch unit 23, and power is supplied from the second power supply unit 12 to the first load 14 and the second load 15.

[0069] After switching the first switch unit 21 to the OFF state, the control unit 40 returns the first switch unit 21 to the ON state when a first return condition is met. The first return condition may be, for example, that the voltage of the power path 13 becomes equal to or lower than a first return voltage, that a predetermined time has elapsed since the first switch unit 21 was switched to the OFF state, or that a condition is met every time a first time shorter than the second time has elapsed before a second time has elapsed since the first switch unit 21 was switched to the OFF state. The first return voltage may be the same value as the overvoltage threshold value or may be a value smaller than the overvoltage threshold value.

[0070] After switching the second switch unit 22 to the OFF state, the control unit 40 switches the second switch unit 22 back to the ON state when a second return condition is met. The second return condition may be, for example, that the voltage of the power path 13 is equal to or greater than a second return voltage, that the state in which an overcurrent flows into the second power supply unit 12 is resolved, that a predetermined time has elapsed since the first switch unit 21 was switched to the OFF state, or that the condition is met every time a first time period shorter than the second time period has elapsed before the second time period has elapsed since the first switch unit 21 was switched to the OFF state. The second return voltage may be the same value as the low-voltage threshold value or may be a value greater than the low-voltage threshold value.

[0071] After switching the third switch unit 23 to the OFF state, the control unit 40 switches the third switch unit 23 back to the ON state when a third return condition is met. The third return condition may be, for example, that the voltage of the power path 13 is equal to or greater than a third return voltage, that the state in which an overcurrent flows into the first power supply unit 11 is resolved, that a predetermined time has elapsed since the first switch unit 21 was switched to the OFF state, or that the condition is met every time a first time period shorter than the second time period has elapsed before a second time period has elapsed since the first switch unit 21 was switched to the OFF state. The third return voltage may be the same value as the low-voltage threshold value or may be a value greater than the low-voltage threshold value.

[0072] 2-3. Effects of the Vehicle Circuit Breaker 220 When the voltage of the power path 13 becomes an overvoltage, the vehicle circuit breaker 220 switches the first switch unit 21 to the OFF state, thereby preventing an overvoltage from being applied to the first load 14, which has a low withstand voltage, and the first power supply unit 11, which also has a low withstand voltage, while supplying power to the second load 15, which has a high withstand voltage. Furthermore, when the voltage of the power path 13 becomes a low voltage, the vehicle circuit breaker 220 switches the second switch unit 22 and the third switch unit 23 to the OFF state while maintaining the first switch unit 21 in the ON state. As a result, the vehicle circuit breaker 220 can supply power from the second power supply unit 12 to the first load 14 and the second load 15 when a ground fault occurs in the first power supply unit 11, and can supply power from the first power supply unit 11 to the first load 14 and the second load 15 when a ground fault occurs in the second power supply unit 12.

[0073] When the voltage of the power path 13 becomes an overvoltage, the vehicle circuit breaker 220 switches the first switch unit 21 to the OFF state, thereby preventing an overvoltage from being applied to the first load 14, which has a low withstand voltage, and the first power supply unit 11, which also has a low withstand voltage, while supplying power to the second load 15, which has a high withstand voltage. Moreover, the vehicle circuit breaker 220 switches the third switch unit 23 to the OFF state when an overcurrent flows into the first power supply unit 11. This allows the vehicle circuit breaker 220 to supply power from the second power supply unit 12 to the first load 14 and the second load 15 even when a ground fault occurs in the first power supply unit 11. Furthermore, the vehicle circuit breaker 220 switches the second switch unit 22 to the OFF state when an overcurrent flows into the second power supply unit 12. This allows the vehicle circuit breaker 220 to supply power from the first power supply unit 11 to the first load 14 and the second load 15 even when a ground fault occurs in the second power supply unit 12.

[0074] <Other Embodiments> The present disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of features of the above-described or below-described embodiments is possible within a range that does not contradict. Furthermore, any feature of the above-described or below-described embodiments may be omitted unless explicitly stated as essential. Furthermore, the above-described embodiments may be modified as follows.

[0075] In the first embodiment, the first switch section and the second switch section are each configured with one MOSFET. However, the first switch section and the second switch section may be configured with two MOSFETs connected in opposite directions.

[0076] In the second embodiment, the first switch unit, the second switch unit, and the third switch unit are each configured with one MOSFET. However, the first switch unit, the second switch unit, and the third switch unit may each be configured with two MOSFETs connected in opposite directions.

[0077] It should be noted that 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, and is intended to include all modifications within the scope indicated by the claims or within the scope equivalent to the claims.

[0078] DESCRIPTION OF SYMBOLS 1...In-vehicle system 11...First power supply unit 11A...Battery 12...Second power supply unit 12A...Power supply source 12B...Voltage conversion unit 13...Power path 13A...First conductive path 13B...Second conductive path 13C...Third conductive path 14...First load 15...Second load 16...First branch path 17...Second branch path 20...In-vehicle circuit breaker 21...First switch unit 22...Second switch unit 23...Third switch unit 31...Voltage detection unit 32...Voltage detection unit 33...Voltage detection unit 34...Current detection unit 35...Current detection unit 40...Control unit 41...Electrical connection box 201...In-vehicle system 220...In-vehicle circuit breaker

Claims

1. An on-board circuit breaker included in an on-board system comprising a first power supply unit, a second power supply unit, a power path provided between the first power supply unit and the second power supply unit, a first load connected to the power path via a first branch path, and a second load connected to the power path via a second branch path on the second power supply unit side of the first load, wherein the withstand voltage of the first power supply unit is lower than the withstand voltage of the second power supply unit, and the withstand voltage of the first load is lower than the withstand voltage of the second load, and the on-board circuit breaker has a first switch unit provided in a conduction path between the first load and the second load on the power path, and the first switch unit switches between an on state that allows current to flow from the second power supply unit side to the first load side and an off state that cuts off current flowing from the second power supply unit side to the first load side.

2. The vehicle-mounted circuit breaker device according to claim 1, wherein the first power supply unit includes a battery and applies the output voltage of the battery to the power path, and the second power supply unit includes a power supply source and a voltage conversion unit that steps up or steps down the voltage input from the power supply source and outputs it, and applies the output voltage of the voltage conversion unit to the power path.

3. The on-board circuit breaker device according to claim 2, further comprising a control unit that controls the first switch unit, wherein the control unit switches the first switch unit to an off state when the voltage of the power path becomes an overvoltage while the first switch unit is in an on state.

4. The on-board circuit breaker according to claim 3, further comprising a second switch unit provided on the power path closer to the second power supply unit than the second load, wherein the second switch unit switches between an ON state that allows current to flow from the second load side to the second power supply unit side and an OFF state that cuts off current flowing from the second load side to the second power supply unit side, and wherein the control unit switches the first switch unit to the OFF state when the voltage of the power path becomes an overvoltage while the first switch unit and the second switch unit are in the ON state, and switches the second switch unit to the OFF state while maintaining the first switch unit in the ON state when the voltage of the power path becomes an undervoltage.

5. The on-board circuit breaker according to claim 3, further comprising a second switch unit provided on the power path closer to the second power supply unit than the second load, wherein the second switch unit switches between an on state that allows current to flow from the first power supply unit side to the second power supply unit side and an off state that cuts off current flowing from the first power supply unit side to the second power supply unit side, and wherein the control unit switches the first switch unit to the off state when the voltage of the power path becomes an overvoltage while the first switch unit and the second switch unit are in the on state, and switches the second switch unit to the off state while maintaining the first switch unit in the on state when an overcurrent flows into the second power supply unit.

6. The vehicle-mounted circuit breaker device according to claim 3, wherein the control unit switches the first switch unit to the off state, and then, when a reset condition is met, switches the first switch unit back to the on state.

7. The vehicle-mounted circuit breaker device according to claim 4 or claim 5, wherein the control unit switches the first switch unit or the second switch unit to the off state, and then, when a restoration condition is met, restores the first switch unit or the second switch unit that has been switched to the off state to the on state.

8. An on-board circuit breaker according to claim 4 or claim 5, further comprising a third switch unit provided on the power path closer to the first power supply unit than the first load, the third switch unit being switchable between an on state that allows current to flow from the second power supply unit side to the first power supply unit side, and an off state that cuts off current flowing from the second power supply unit side to the first power supply unit side.

9. The vehicle-mounted circuit breaker device according to claim 8, wherein the control unit switches the first switch unit to an off state when the voltage of the power path becomes an overvoltage while the first switch unit, the second switch unit, and the third switch unit are in an on state, and switches the second switch unit and the third switch unit to an off state while maintaining the first switch unit in an on state when the voltage of the power path becomes an undervoltage.

10. The vehicle-mounted circuit breaker device according to claim 8, wherein the control unit switches the first switch unit to the off state when the voltage of the power path becomes an overvoltage while the first switch unit, the second switch unit, and the third switch unit are in the on state, switches the third switch unit to the off state when an overcurrent flows into the first power supply unit, and switches the second switch unit to the off state when an overcurrent flows into the second power supply unit.

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