On-vehicle control device

Abstract

An on-vehicle control device (20) has a first switch unit (21), a protection circuit (30), and a control unit (40). The first switch unit (21) is provided in a power path (12) that supplies power from a power supply unit (10) to a load (11). The protection circuit (30) is provided in parallel with the first switch unit (21), and has a configuration in which a surge absorber (31) and a second switch unit (32) are connected in series. The control unit (40) controls the first switch unit (21) and the second switch unit (32). When the power path (12) is in an abnormal state, the control unit (40) switches the first switch unit (21) to an off state while controlling the second switch unit (32) to be in an on state, and then switches the second switch unit (32) to the off state.

Description

In-vehicle control device

[0001] The present disclosure relates to an in-vehicle control device.

[0002] Patent Document 1 discloses a protection circuit. This protection circuit includes a switch located on a power line from a storage element to a load, and a protection element connected in parallel to the switch. The protection element absorbs a surge that occurs when the switch opens to cut off the discharge current.

[0003] Japanese Patent Application Laid-Open No. 2021-93825

[0004] In the configuration of Patent Document 1, as the voltage increases, the size and number of surge absorbers (protective elements) tend to increase.

[0005] An object of the present disclosure is to provide a technique that can suppress an increase in the size and number of surge absorbers.

[0006] The vehicle-mounted control device disclosed herein includes: a first switch unit provided in a power path that supplies power from a power supply unit to a load; a protection circuit that is provided in parallel to the first switch unit and has a surge absorber and a second switch unit connected in series; and a control unit that controls the first switch unit and the second switch unit, wherein when the power path falls into an abnormal state, the control unit switches the first switch unit to an off state while controlling the second switch unit to an on state, and then switches the second switch unit to an off state.

[0007] The technology according to the present disclosure can prevent surge absorbers from becoming larger and increasing in number.

[0008] FIG. 1 is a configuration diagram of an in-vehicle system according to a first embodiment. FIG. 2 is a configuration diagram of an in-vehicle control device according to the first embodiment. FIG. 3 is a configuration diagram of an in-vehicle control device according to a second embodiment. FIG. 4 is a configuration diagram of an in-vehicle control device according to a third embodiment. FIG. 5 is a configuration diagram of an in-vehicle control device according to a fourth embodiment. FIG. 6 is a configuration diagram of an in-vehicle control device according to a fifth embodiment. FIG. 7 is an explanatory diagram showing a state in which a current flows through a surge absorber according to the fifth embodiment. FIG. 8 is an explanatory diagram showing a state in which a capacitor discharges according to the fifth embodiment.

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

[0010] [1] An in-vehicle control device comprising: a first switch unit provided in a power path that supplies power from a power supply unit to a load; a protection circuit that is provided in parallel to the first switch unit and has a configuration in which a surge absorber and a second switch unit are connected in series; and a control unit that controls the first switch unit and the second switch unit, wherein when the power path falls into an abnormal state, the control unit switches the first switch unit to an off state while controlling the second switch unit to an on state, and then switches the second switch unit to an off state.

[0011] When the power path becomes abnormal, the control unit switches the first switch unit to the OFF state while controlling the second switch unit to the ON state. A surge current is generated when the first switch unit is switched to the OFF state. This surge current flows to the protection circuit and is absorbed by the surge absorber. This reduces the impact of the surge on the first switch unit and suppresses failure of the first switch unit. Furthermore, after switching the first switch unit to the OFF state, the control unit switches the second switch unit to the OFF state. This blocks the current flowing through the surge absorber, thereby shortening the time that current flows through the surge absorber compared to a configuration in which the current flowing through the surge absorber is not blocked. Therefore, with the above-mentioned on-board control device, the current withstand capacity required of the surge absorber is reduced, making it possible to suppress increases in the size and number of surge absorbers.

[0012] [2] The vehicle-mounted control device according to [1], wherein the control unit switches the second switch unit to the off state after a predetermined time has elapsed since the first switch unit was switched to the off state.

[0013] The time required to absorb the surge is determined to some extent by the configuration of the in-vehicle system. The in-vehicle control device can absorb the surge current and then switch the second switch unit to the off state by a simple configuration in which the first switch unit is switched to the off state and then the second switch unit is switched to the off state after a predetermined time has elapsed.

[0014] [3] The control unit has a cutoff control unit that switches the first switch unit to an off state, and a delay circuit, wherein the cutoff control unit outputs a cutoff signal to the first switch unit and the delay circuit when the power path is in an abnormal state, the first switch unit switches to an off state when the cutoff signal is input, the delay circuit delays the input cutoff signal by the predetermined time and outputs it to the second switch unit, and the second switch unit switches to an off state when the cutoff signal is input. The in-vehicle control device described in [2].

[0015] The above-described on-vehicle control device can delay the cutoff signal input to the second switch unit by a predetermined time by using the delay circuit.

[0016] [4] The control unit for an in-vehicle device described in [1], wherein after switching the first switch unit to the off state, the control unit switches the second switch unit to the off state when the voltage across the first switch unit becomes equal to or lower than a threshold voltage set to be equal to or lower than the rated voltage of the first switch unit.

[0017] With this configuration, the second switch unit is switched to the OFF state when the voltage across the first switch unit is equal to or less than the rated voltage of the first switch unit. This prevents a voltage exceeding the rated voltage from being applied to the first switch unit when the second switch unit is switched to the OFF state. This makes the first switch unit less likely to fail.

[0018] [5] The vehicle-mounted control device according to [4], wherein the threshold voltage is set to a value equal to or lower than a normal voltage applied from the power supply unit to the load when the power path is in a normal state.

[0019] With this configuration, the second switch unit is switched to the OFF state when the voltage across the first switch unit is equal to or lower than the normal voltage, so that the voltage applied to the first switch unit when the second switch unit is switched to the OFF state is equal to or lower than the normal voltage, making the first switch unit less susceptible to failure.

[0020] [6] The vehicle control device described in [1], wherein the control unit switches the second switch unit to the off state when the current flowing through the surge absorber becomes equal to or less than a threshold current after switching the first switch unit to the off state.

[0021] According to this configuration, the second switch unit can be switched to the off state after suppressing the current flowing through the surge absorber to a threshold current or less.

[0022] [7] The vehicle-mounted control device according to [1], further comprising: a capacitor provided in parallel to the surge absorber; and a third switch unit, wherein the second switch unit is constituted by a thyristor, and when the third switch unit is in an on state, the third switch unit forms a closed circuit in which the thyristor and the capacitor are connected in series, separate from a circuit passing through the first switch unit, and when the power path is in an abnormal state, the control unit switches the first switch unit to an off state while controlling the thyristor to an on state and the third switch unit to an off state, and then inputs an off signal to the gate of the thyristor, switches the third switch unit to an on state, and discharges the capacitor, thereby switching the thyristor to an off state.

[0023] The in-vehicle control device can increase the surge current flowing through the surge absorber by configuring the second switch unit with a thyristor. Moreover, the in-vehicle control device can switch the thyristor to the off state by discharging the capacitor.

[0024] [8] The vehicle control device described in [7], wherein the control unit controls the first switch unit to an off state, controls the thyristor to an on state, and controls the third switch unit to an off state, and continues this state for a predetermined charging time, and then switches the third switch unit to an on state, and the charging time is set to be equal to or longer than the time required to charge the capacitor with the power required to switch the thyristor to the off state.

[0025] The above-described on-vehicle control device can more reliably switch the thyristor to the off state when the third switch unit is switched to the on state.

[0026] [9] The vehicle-mounted control device according to any one of [1] to [8], wherein the surge absorber includes at least one of a varistor, a Zener diode, and an arrester.

[0027] The above-mentioned on-vehicle control device can absorb surge currents by at least one of a varistor, a Zener diode, and an arrester.

[0028]

[10] The control unit of the vehicle control device described in any one of [1] to [9] returns the second switch unit to the on state after switching the second switch unit to the off state, and then returns the first switch unit to the on state, or when returning the first switch unit to the on state.

[0029] If the second switch unit is switched on while the first switch unit remains off, a current will flow through the surge absorber. The above-described vehicle control device can avoid such a situation.

[0030] [Details of the embodiment of the present disclosure] 1. First embodiment An in-vehicle system 1 according to the first embodiment is a system mounted on a vehicle, as shown in Fig. 1. The in-vehicle system 1 includes a power supply unit 10, a load 11, a power path 12, main relays 13 and 14, a fuse 15, and an in-vehicle control device 20.

[0031] The power supply unit 10 is configured by, for example, an on-board battery. The power path 12 is a path for supplying power from the power supply unit 10 to the load 11. The power path 12 has a positive power line 12A and a negative power line 12B. Main relays 13 and 14 are provided on the power path 12. The main relay 13 is provided on the positive power line 12A. The main relay 14 is provided on the negative power line 12B. A fuse 15 is provided on the power path 12. The fuse 15 is provided between the power supply unit 10 and the main relay 13.

[0032] The on-board control device 20 has a first switch unit 21 provided on the power path 12. The first switch unit 21 is provided on the positive power line 12A between the main relay 13 and the load 11. The first switch unit 21 may be configured with a mechanical switch or a semiconductor switching element. The positive power line 12A includes a first conductive path 12C provided closer to the power supply unit 10 than the first switch unit 21, and a second conductive path 12D provided closer to the load 11 than the first switch unit 21.

[0033] As shown in FIG. 2 , the vehicle control device 20 includes a protection circuit 30 and a control unit 40 .

[0034] The protection circuit 30 is provided in parallel with the first switch unit 21. One end of the protection circuit 30 is electrically connected to the first conductive path 12C, and the other end of the protection circuit 30 is electrically connected to the second conductive path 12D. The protection circuit 30 is configured by connecting a surge absorber 31 and a second switch unit 32 in series. The surge absorber 31 includes, for example, at least one of a varistor, a Zener diode, and an arrester. The surge absorber 31 is provided closer to the power supply unit 10 than the second switch unit 32. The second switch unit 32 may be configured by a mechanical switch or a semiconductor switching element.

[0035] The control unit 40 controls the first switch unit 21 and the second switch unit 32. When the power path 12 is in an abnormal state, the control unit 40 switches the first switch unit 21 to an OFF state while controlling the second switch unit 32 to an ON state, and then switches the second switch unit 32 to an OFF state.

[0036] The control unit 40 includes a main control unit 41 and a sub-control unit 42. The main control unit 41 controls the first switch unit 21 and the second switch unit 32. The main control unit 41 is configured, for example, by a microcomputer. When the power path 12 is in a normal state, the main control unit 41 maintains the first switch unit 21 in an ON state. When the power path 12 is in a normal state, the main control unit 41 may control the second switch unit 32 to an ON state or an OFF state. However, when the power path 12 is in an abnormal state, the main control unit 41 switches the second switch unit 32 to an ON state if the second switch unit 32 is in an OFF state, and maintains the second switch unit 32 in an ON state until the first switch unit 21 switches to an OFF state. The normal state of the power path 12 refers to, for example, a state in which the voltage, current, or temperature of the power path 12 is normal.

[0037] When an abnormal state occurs in the power path 12, the sub-controller 42 interrupts the control by the main controller 41 and switches the first switch unit 21 and the second switch unit 32 to the OFF state. The sub-controller 42 includes an abnormality determination unit 43 and a cutoff controller 44.

[0038] The abnormality determination unit 43 determines whether the power path 12 has entered an abnormal state. An abnormal state of the power path 12 refers to, for example, a state in which the voltage, current, or temperature of the power path 12 is abnormal. The abnormality determination unit 43 determines whether the power path 12 has entered an abnormal state based on the detection result by the detection unit 22 of the onboard control device 20. The detection unit 22 detects, for example, the voltage, current, or temperature of the power path 12. The abnormality determination unit 43 may determine that the power path 12 is in an abnormal state when the voltage of the power path 12 is equal to or lower than a threshold voltage. Alternatively, the abnormality determination unit 43 may determine that the power path 12 is in an abnormal state when the current flowing through the power path 12 exceeds a threshold current. Alternatively, the abnormality determination unit 43 may determine that the power path 12 is in an abnormal state when the temperature of the power path 12 exceeds a threshold temperature. When the abnormality determination unit 43 determines that the power path 12 has entered an abnormal state, it outputs an abnormality notification signal to the cutoff control unit 44. The abnormality determination unit 43 is configured by, for example, a hardware circuit.

[0039] The cutoff control unit 44 is configured by, for example, a microcomputer. When the cutoff control unit 44 receives an abnormality notification signal from the abnormality determination unit 43, the cutoff control unit 44 switches the first switch unit 21 to the OFF state, and then switches the second switch unit 32 to the OFF state. The cutoff control unit 44 switches the second switch unit 32 to the OFF state after a predetermined time has elapsed since switching the first switch unit 21 to the OFF state.

[0040] The predetermined time is set to, for example, a value equal to or greater than the following lower limit and equal to or less than the following upper limit. The lower limit of the predetermined time is the time required for the surge energy generated when the power path 12 goes into an abnormal state to be absorbed by the energy loss of the first switch unit 21 and the surge absorber 31. The lower limit of the predetermined time is, for example, t1 that satisfies the conditions of the following equations (1) to (3): E1=(½)×L×I １ ２ ...Formula (1) Equation (2) E1=E2 Equation (3) E1: surge energy expected to occur when the power path 12 is in an abnormal state. L: inductance of the power path 12. I １I: the current that flows through the power line 12 when the power line 12 is in an abnormal state. ２ I: the current that flows through the first switch unit 21 when the power path 12 is in an abnormal state. ３ : Current that flows through the surge absorber 31 when the power path 12 is in an abnormal state. V: Voltage that is applied to the first switch unit 21 and the surge absorber 31 when the power path 12 is in an abnormal state.

[0041] The upper limit of the predetermined time is, for example, the maximum time that the surge absorber 31 will not fail. The upper limit of the predetermined time is, for example, t2 that satisfies the condition of the following equation (4): E3=I ４ ×VS×(t2−t1) Equation (4) E3: Maximum value of loss energy that can be tolerated by the surge absorber 31. I ４ : Current that flows through the surge absorber 31 when the power line 12 is in an abnormal state. VS: Voltage that is applied to the power line 12 when the power line 12 is in a normal state.

[0042] As described above, when the power path 12 is in an abnormal state, the control unit 40 switches the first switch unit 21 to the OFF state while controlling the second switch unit 32 to the ON state. Switching the first switch unit 21 to the OFF state generates a surge current. This surge current flows to the protection circuit 30 and is absorbed by the surge absorber 31. This reduces the impact of the surge on the first switch unit 21 and prevents failure of the first switch unit 21. Furthermore, after switching the first switch unit 21 to the OFF state, the control unit 40 switches the second switch unit 32 to the OFF state. This blocks the current flowing through the surge absorber 31, thereby shortening the time that current flows through the surge absorber 31 compared to a configuration in which the current flowing through the surge absorber 31 is not blocked. Therefore, the in-vehicle control device 20 reduces the current resistance required of the surge absorber 31, thereby preventing an increase in the size and number of surge absorbers 31.

[0043] The time required to absorb the surge is determined to some extent by the configuration of the in-vehicle system 1. The in-vehicle control device 20 has a simple configuration in which the first switch unit 21 is switched to the off state and then the second switch unit 32 is switched to the off state a predetermined time later, and thus can absorb the surge current and then switch the second switch unit 32 to the off state.

[0044] Furthermore, after switching the second switch unit 32 to the OFF state, the control unit 40 returns the first switch unit 21 to the ON state and then returns the second switch unit 32 to the ON state. Alternatively, after switching the second switch unit 32 to the OFF state, the control unit 40 returns the second switch unit 32 to the ON state when returning the first switch unit 21 to the ON state. If the second switch unit 32 is switched to the ON state while the first switch unit 21 remains in the OFF state, a current will flow through the surge absorber 31. This configuration makes it possible to avoid such a situation.

[0045] 2. Second Embodiment In the second embodiment, a configuration will be described in which a delay circuit is used to achieve control of switching the first switch unit to the off state and then switching the second switch unit to the off state. Note that in the second embodiment, the same components as in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0046] An in-vehicle control device 220 of the second embodiment shown in Fig. 3 is applied in place of the in-vehicle control device 20 in the in-vehicle system 1 shown in Fig. 1. The in-vehicle control device 220 has a first switch unit 21, a detection unit 22, a protection circuit 30, and a control unit 240. The control unit 240 has a main control unit 41 and a sub-control unit 242.

[0047] The sub-control unit 242 is configured, for example, by a hardware circuit. The sub-control unit 242 includes an abnormality determination unit 43, a shutdown control unit 244, and a delay circuit 245. The shutdown control unit 244 outputs a shutdown signal to the first switch unit 21 and the delay circuit 245 when an abnormality occurs in the power path 12. Specifically, when the shutdown control unit 244 receives an abnormality notification signal from the abnormality determination unit 43, it outputs the shutdown signal to the first switch unit 21 and the delay circuit 245. The first switch unit 21 switches to the OFF state when the shutdown signal is input. The delay circuit 245 delays the input shutdown signal by a predetermined time and outputs the delayed signal to the second switch unit 32. The second switch unit 32 switches to the OFF state when the shutdown signal is input.

[0048] As described above, the on-board control device 220 can delay the disconnection signal input to the second switch section 32 by a predetermined time by using the delay circuit 245 .

[0049] 3. Third Embodiment In the third embodiment, a configuration will be described in which, after the first switch unit is switched to the off state, the second switch unit is switched to the off state when the voltage across the first switch unit becomes equal to or lower than a threshold voltage. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0050] An in-vehicle control device 320 of the third embodiment shown in Fig. 4 is applied in place of the in-vehicle control device 20 in the in-vehicle system 1 shown in Fig. 1. The in-vehicle control device 320 has a first switch unit 21, a detection unit 22, a protection circuit 30, a control unit 340, and an end-to-end voltage detection unit 350. The end-to-end voltage detection unit 350 detects the voltage across the first switch unit 21 and outputs an end-to-end voltage signal indicating the detection result.

[0051] The control unit 340 includes a main control unit 41 and a sub-control unit 342. The sub-control unit 342 is configured, for example, by a hardware circuit. The sub-control unit 342 includes an abnormality determination unit 43, a shutdown control unit 344, and a logic circuit 345.

[0052] When the power path 12 enters an abnormal state, the cutoff control unit 344 outputs a cutoff signal to the first switch unit 21 and the logic circuit 345. Specifically, when the cutoff control unit 344 receives an abnormality notification signal from the abnormality determination unit 43, it outputs the cutoff signal to the first switch unit 21 and the logic circuit 345.

[0053] A shutdown signal output from the shutdown control unit 344 is input to a first terminal 345A of the logic circuit 345. A voltage signal from the voltage detection unit 350 is input to a second terminal 345B of the logic circuit 345. When a shutdown signal is input to the first terminal 345A and the voltage value indicated by the voltage signal input to the second terminal 345B is equal to or lower than a threshold voltage, the logic circuit 345 outputs a shutdown signal from the third terminal 345C to the second switch unit 32. The threshold voltage is set to be equal to or lower than the rated voltage of the first switch unit 21. The threshold voltage is set to be equal to or lower than the normal voltage applied from the power supply unit 10 to the load 11 when the power path 12 is in a normal state. When a shutdown signal is not input to the first terminal 345A, the logic circuit 345 does not output a shutdown signal from the third terminal 345C. When the voltage value indicated by the voltage signal input to the second terminal 345B exceeds the threshold voltage, the logic circuit 345 does not output a cutoff signal from the third terminal 345C.

[0054] Therefore, when the shutdown control unit 344 outputs a shutdown signal to the first switch unit 21 and the logic circuit 345, the first switch unit 21 is first switched to the OFF state. When the first switch unit 21 is switched to the OFF state, the voltage across the first switch unit 21 exceeds the threshold voltage. When the voltage across the first switch unit 21 exceeds the threshold voltage, the logic circuit 345 does not output a shutdown signal, and the second switch unit 32 is maintained in the ON state. Thereafter, when the surge is absorbed by the surge absorber 31 and the voltage across the first switch unit 21 falls below the threshold voltage, the logic circuit 345 outputs a shutdown signal from the third terminal 345C. This switches the second switch unit 32 to the OFF state.

[0055] In this way, after switching the first switch section 21 to the OFF state, the control section 340 switches the second switch section 32 to the OFF state when the voltage across the first switch section 21 becomes equal to or lower than the threshold voltage.

[0056] With this configuration, the second switch section 32 is switched to the OFF state when the voltage across the first switch section 21 is equal to or less than the rated voltage of the first switch section 21. This prevents a voltage exceeding the rated voltage from being applied to the first switch section 21 when the second switch section 32 is switched to the OFF state. This makes the first switch section 21 less likely to break down.

[0057] Furthermore, the threshold voltage is set to be equal to or lower than the normal voltage applied from the power supply unit 10 to the load 11 when the power path 12 is in a normal state. With this configuration, the second switch unit 32 switches to the OFF state when the voltage across the first switch unit 21 is equal to or lower than the normal voltage, so that the voltage applied to the first switch unit 21 when the second switch unit 32 switches to the OFF state is equal to or lower than the normal voltage. This makes the first switch unit 21 less susceptible to failure.

[0058] 4. Fourth Embodiment In the fourth embodiment, a configuration will be described in which, after the first switch unit is switched to the off state, the second switch unit is switched to the off state when the current flowing through the surge absorber becomes equal to or less than a threshold current. In the fourth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0059] An in-vehicle control device 420 of the fourth embodiment shown in Fig. 5 is applied in place of the in-vehicle control device 20 in the in-vehicle system 1 shown in Fig. 1. The in-vehicle control device 420 has a first switch unit 21, a detection unit 22, a protection circuit 30, a control unit 440, and a current detection unit 450. The current detection unit 450 detects the current flowing through the surge absorber 31 and outputs a current value signal indicating the detection result.

[0060] The control unit 440 includes a main control unit 41 and a sub-control unit 442. The sub-control unit 442 is configured, for example, by a hardware circuit. The sub-control unit 442 includes an abnormality determination unit 43, a shutdown control unit 444, and a logic circuit 445.

[0061] When the power path 12 enters an abnormal state, the cutoff control unit 444 outputs a cutoff signal to the first switch unit 21 and the logic circuit 445. Specifically, when the cutoff control unit 444 receives an abnormality notification signal from the abnormality determination unit 43, it outputs the cutoff signal to the first switch unit 21 and the logic circuit 445.

[0062] A shutdown signal output from the shutdown control unit 444 is input to a first terminal 445A of the logic circuit 445. A current value signal from the current detection unit 450 is input to a second terminal 445B of the logic circuit 445. When a shutdown signal is input to the first terminal 445A and the current value indicated by the current value signal input to the second terminal 445B is equal to or less than the threshold current, the logic circuit 445 outputs a shutdown signal from the third terminal 445C to the second switch unit 32. When a shutdown signal is not input to the first terminal 445A, the logic circuit 445 does not output a shutdown signal from the third terminal 445C. When the current value indicated by the current value signal input to the second terminal 445B exceeds the threshold current, the logic circuit 445 does not output a shutdown signal from the third terminal 445C.

[0063] Therefore, when the cutoff control unit 444 outputs a cutoff signal to the first switch unit 21 and the logic circuit 445, the first switch unit 21 is first switched to the OFF state. When the first switch unit 21 is switched to the OFF state, the value of the current flowing through the surge absorber 31 exceeds the threshold current. When the value of the current flowing through the surge absorber 31 exceeds the threshold current, the logic circuit 445 does not output a cutoff signal, and the second switch unit 32 is maintained in the ON state. Thereafter, when the surge current is absorbed by the surge absorber 31 and the value of the current flowing through the surge absorber 31 becomes equal to or less than the threshold current, the logic circuit 445 outputs a cutoff signal from the third terminal 445C. This switches the second switch unit 32 to the OFF state.

[0064] In this way, after switching the first switch unit 21 to the OFF state, the control unit 440 switches the second switch unit 32 to the OFF state when the current flowing through the surge absorber 31 becomes equal to or less than the threshold current.

[0065] According to this configuration, the second switch unit 32 can be switched to the OFF state after suppressing the current flowing through the surge absorber 31 to a threshold current or less.

[0066] 5. Fifth Embodiment In the fifth embodiment, an example in which the second switch unit is configured by a thyristor will be described. Note that in the fifth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0067] An in-vehicle control device 520 of the fifth embodiment shown in Fig. 6 is applied in place of the in-vehicle control device 20 in the in-vehicle system 1 shown in Fig. 1. The in-vehicle control device 520 has a first switch unit 21, a detection unit 22, a protection circuit 530, a control unit 540, a capacitor 550, a third switch unit 551, a first resistor unit 552, and a second resistor unit 553.

[0068] The protection circuit 530 includes a surge absorber 31 and a second switch unit 532. The second switch unit 532 is configured by a thyristor 533.

[0069] The capacitor 550 is provided in parallel with the surge absorber 31 and in series with the thyristor 533 .

[0070] The third switch unit 551 may be configured by a mechanical switch or a semiconductor switching element. When the third switch unit 551 itself is in an on state, it forms a closed circuit in which the thyristor 533 and the capacitor 550 are connected in series, separate from the circuit that passes through the first switch unit 21.

[0071] The first resistor 552 is provided closer to the power supply unit 10 than the capacitor 550. The second resistor 553 is provided closer to the power supply unit 10 than the third switch unit 551. One end of the first resistor 552 is electrically connected to the first conductive path 12C and one end of the surge absorber 31. The other end of the first resistor 552 is electrically connected to one end of the capacitor 550 and one end of the second resistor 553. The other end of the second resistor 553 is electrically connected to one end of the third switch unit 551. The other end of the surge absorber 31 is electrically connected to the anode of the thyristor 533. The cathode of the thyristor 533 is electrically connected to the second conductive path 12D.

[0072] The control unit 540 controls the first switch unit 21, the second switch unit 532, and the third switch unit 551. When the power path 12 is in an abnormal state, the control unit 540 controls the thyristor 533 to the on state and the third switch unit 551 to the off state, and switches the first switch unit 21 to the off state. Thereafter, the control unit 540 inputs an off signal to the gate of the thyristor 533, switches the third switch unit 551 to the on state, and discharges the capacitor 550. This switches the thyristor 533 to the off state.

[0073] The control unit 540 has a main control unit 41 and a sub-control unit 542. The main control unit 41 controls the first switch unit 21, the second switch unit 532, and the third switch unit 551. The main control unit 41 maintains the third switch unit 551 in an off state when the power path 12 is in a normal state.

[0074] When an abnormal state occurs in the power path 12, the sub-controller 542 interrupts the control by the main controller 41 and controls the first switch unit 21, the second switch unit 532, and the third switch unit 551. The sub-controller 542 includes an abnormality determination unit 43, a cutoff controller 544, and a delay circuit 545.

[0075] The cutoff control unit 544 is configured by, for example, a microcomputer. When the cutoff control unit 544 receives an abnormality notification signal from the abnormality determination unit 43, it controls the thyristor 533 to an ON state and the third switch unit 551 to an OFF state, and outputs a cutoff signal to the first switch unit 21 and the delay circuit 545. When the cutoff signal is input, the first switch unit 21 switches to an OFF state. The delay circuit 545 delays the input cutoff signal by a predetermined time and outputs it to the gate of the thyristor 533. However, the thyristor 533 may not switch to an OFF state just by inputting the cutoff signal to the gate.

[0076] 7, after the first switch section 21 is switched to the OFF state, a current flows through the surge absorber 31 and is also supplied to the capacitor 550. As a result, the capacitor 550 is charged.

[0077] The cutoff control unit 544 controls the first switch unit 21 to the OFF state, the thyristor 533 to the ON state, and the third switch unit 551 to the OFF state, and these states continue for a predetermined charging time. After the charging time has elapsed, the cutoff control unit 544 switches the third switch unit 551 to the ON state. The charging time is set to be equal to or longer than the time required to charge the capacitor 550 with the power required to switch the thyristor 533 to the OFF state. When the third switch unit 551 is switched to the ON state, as shown in FIG. 8, the capacitor 550 discharges toward the cathode of the thyristor 533. This switches the thyristor 533 to the OFF state.

[0078] As described above, by configuring the second switch unit 532 using the thyristor 533, the on-board control device 520 can increase the surge current flowing through the surge absorber 31. Moreover, the on-board control device 520 can switch the thyristor 533 to the off state by discharging the capacitor 550.

[0079] Furthermore, the control unit 540 continues, for a predetermined charging time, a state in which the first switch unit 21 is controlled to the OFF state, the thyristor 533 is controlled to the ON state, and the third switch unit 551 is controlled to the OFF state. With this configuration, when the third switch unit 551 is switched to the ON state, the thyristor 533 can be switched to the OFF state more reliably.

[0080] 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.

[0081] 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.

[0082] REFERENCE SIGNS LIST 1...In-vehicle system 10...Power supply unit 11...Load 12...Power path 12A...Positive power line 12B...Negative power line 12C...First conductive path 12D...Second conductive path 13...Main relay 14...Main relay 15...Fuse 20...In-vehicle control device 21...First switch unit 22...Detection unit 30...Protection circuit 31...Surge absorber 32...Second switch unit 40...Control unit 41...Main control unit 42...Sub-control unit 43...Abnormality determination unit 44...Shut-off control unit 220...In-vehicle control device 240...Control unit 242...Sub-control unit 244...Shut-off control unit 245...Delay circuit 320...In-vehicle control device 340...Control unit 342...Sub-control unit 344...Shut-off control unit 345...Logic circuit 345A...First terminal 345B...Second terminal 345C...Third terminal 350...End-of-end voltage detection unit 420...In-vehicle control device 440...Control unit 442...Sub-control unit 444...Shutdown control unit 445...Logic circuit 445A...First terminal 445B...Second terminal 445C...Third terminal 450...Current detection unit 520...In-vehicle control device 530...Protection circuit 532...Second switch unit 533...Thyristor 540...Control unit 542...Sub-control unit 544...Shutdown control unit 545...Delay circuit 550...Capacitor 551...Third switch unit 552...First resistor unit 553...Second resistor unit

Claims

1. An in-vehicle control device comprising: a first switch unit provided in a power path that supplies power from a power supply unit to a load; a protection circuit provided in parallel to the first switch unit and configured with a surge absorber and a second switch unit connected in series; and a control unit that controls the first switch unit and the second switch unit, wherein when the power path falls into an abnormal state, the control unit switches the first switch unit to an off state while controlling the second switch unit to an on state, and then switches the second switch unit to an off state.

2. The vehicle-mounted control device according to claim 1, wherein the control unit switches the second switch unit to the OFF state after a predetermined time has elapsed since the first switch unit was switched to the OFF state.

3. The in-vehicle control device according to claim 2, wherein the control unit has a cutoff control unit that switches the first switch unit to an OFF state, and a delay circuit, wherein the cutoff control unit outputs a cutoff signal to the first switch unit and the delay circuit when the power path is in an abnormal state, wherein the first switch unit switches to an OFF state when the cutoff signal is input, wherein the delay circuit delays the input cutoff signal by the predetermined time and outputs it to the second switch unit, and wherein the second switch unit switches to an OFF state when the cutoff signal is input.

4. The in-vehicle control device according to claim 1, wherein the control unit switches the second switch unit to the off state when, after switching the first switch unit to the off state, the voltage across the first switch unit becomes equal to or lower than a threshold voltage set to be equal to or lower than the rated voltage of the first switch unit.

5. The vehicle-mounted control device according to claim 4, wherein the threshold voltage is set to a value equal to or lower than a normal voltage applied from the power supply unit to the load when the power path is in a normal state.

6. The vehicle control device according to claim 1, wherein the control unit switches the second switch unit to the off state when the current flowing through the surge absorber becomes equal to or less than a threshold current after switching the first switch unit to the off state.

7. An on-vehicle control device according to claim 1, comprising: a capacitor provided in parallel to the surge absorber; and a third switch unit, wherein the second switch unit is constituted by a thyristor, and when the third switch unit is in an on state, the third switch unit forms a closed circuit in which the thyristor and the capacitor are connected in series, separate from a circuit passing through the first switch unit, and wherein the control unit, when the power path is in an abnormal state, controls the thyristor to an on state and the third switch unit to an off state, switches the first switch unit to an off state, and then inputs an off signal to the gate of the thyristor, switches the third switch unit to an on state, and discharges the capacitor, thereby switching the thyristor to an off state.

8. The in-vehicle control device according to claim 7, wherein the control unit continues to control the first switch unit to the off state, control the thyristor to the on state, and control the third switch unit to the off state for a predetermined charging time, and then switches the third switch unit to the on state, and the charging time is set to be equal to or longer than the time required to charge the capacitor with the power required to switch the thyristor to the off state.

9. The vehicle-mounted control device according to any one of claims 1 to 8, wherein the surge absorber includes at least one of a varistor, a Zener diode, and an arrester.

10. An in-vehicle control device according to any one of claims 1 to 8, wherein the control unit switches the second switch unit to the off state, and then switches the first switch unit back to the on state, or switches the second switch unit back to the on state when switching the first switch unit back to the on state.

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