On-vehicle control device

Abstract

An on-vehicle control device (20) comprises a first switching unit (21), a second switching unit (22), and a control unit (26). The control unit (26) performs first control for controlling the first switching unit (21) to be in a first permission state and controlling the second switching unit (22) to be in a second cutoff state. When the voltage of a first electric power path (14) becomes equal to or less than a threshold voltage in a state in which the first control is being performed, the control unit (26) performs second control for controlling the first switching unit (21) to be in a first cutoff state and controlling the second switching unit (22) to be in a second permission state. In a state in which the second control is being performed, the control unit (26) performs at least one of cutoff control for switching the second switching unit (22) to the second cutoff state when the electric current flowing through a second electric power path (15) exceeds a cutoff threshold value, and electric current limit control for controlling the second switching unit (22) so as to suppress the electric current flowing through the second electric power path (15) to a limit threshold value or lower when the electric current flowing through the second electric power path (15) exceeds the limit threshold value.

Description

In-vehicle control device

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

[0002] Patent Document 1 discloses an in-vehicle backup power supply control device. This backup power supply control device discharges electricity from a power storage unit to a load when the power supply from a power supply unit fails. This backup power supply control device determines that the power supply from the power supply unit has failed when the voltage of a first conduction path provided between the power supply unit and the load falls below a predetermined first threshold voltage.

[0003] Japanese Patent Application Laid-Open No. 2020-092476

[0004] In the configuration of Patent Document 1, even if the cause is on the load side, such as a ground fault of the load, it may be determined that the power supply from the power supply unit has failed. In this case, when the power storage unit discharges to the load, the discharge current from the power storage unit to the load may exceed an expected current value.

[0005] The present disclosure aims to provide a technique that can easily prevent excessive discharge current from a backup power supply.

[0006] The in-vehicle control device of the present disclosure includes: an in-vehicle control device included in an in-vehicle system including a first power supply unit, a load, a first power path provided between the first power supply unit and the load, a second power supply unit, and a second power path provided between the second power supply unit and the first power path; a first switching unit provided on the first power path closer to the first power supply unit than a connection portion with the second power path; a second switching unit provided on the second power path; and a control unit that controls the first switching unit and the second switching unit, wherein the first switching unit switches between a first permissive state that allows current to flow from the first power supply unit side to the load side and a first blocked state that blocks current from flowing from the load side to the first power supply unit side; and the second switching unit switches between a second permissive state that allows current to flow from the second power supply unit side to the first power path side and a second blocked state that blocks current from flowing from the second power supply unit side to the first power path side, and the control unit When a start condition is met, a first control is performed to control the first switching unit to the first permissive state and the second switching unit to the second cut-off state; when the voltage of the first power path becomes equal to or lower than a threshold voltage while the first control is being performed, a second control is performed to control the first switching unit to the first cut-off state and the second switching unit to the second permissive state; and when the second control is being performed, at least one of a cut-off control to switch the second switching unit to the second cut-off state when the current flowing through the second power path exceeds a cut-off threshold and a current limit control to control the second switching unit to limit the current flowing through the second power path to below the limit threshold when the current flowing through the second power path exceeds a limit threshold is performed.

[0007] The technology according to the present disclosure makes it easy to prevent excessive discharge current from the backup power supply.

[0008] FIG. 1 is a schematic diagram of an in-vehicle system including an in-vehicle control device of a first embodiment. FIG. 2 is a flowchart of processing performed by a control unit of the first embodiment. FIG. 3 is a schematic diagram of an in-vehicle system including an in-vehicle control device of a second embodiment. FIG. 4 is a flowchart of processing performed by a control unit of the second embodiment. FIG. 5 is a schematic diagram of an in-vehicle system including an in-vehicle control device of a third embodiment. FIG. 6 is a flowchart of processing performed by a control unit of the third 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 on-board control device included in an on-board system including a first power supply unit, a load, a first power path provided between the first power supply unit and the load, a second power supply unit, and a second power path provided between the second power supply unit and the first power path; a first switching unit provided on the first power path closer to the first power supply unit than a connection portion with the second power path; a second switching unit provided on the second power path; and a control unit that controls the first switching unit and the second switching unit, wherein the first switching unit switches between a first permissive state that allows current to flow from the first power supply unit side to the load side and a first blocked state that blocks current from flowing from the load side to the first power supply unit side, and the second switching unit switches between a second permissive state that allows current to flow from the second power supply unit side to the first power path side and a second blocked state that blocks current from flowing from the second power supply unit side to the first power path, and the control unit an on-board control device that, when a start condition is satisfied, performs first control to control the first switching unit to the first permissive state and the second switching unit to the second cut-off state; when the voltage of the first power path becomes equal to or lower than a threshold voltage while the first control is being performed, performs second control to control the first switching unit to the first cut-off state and the second switching unit to the second permissive state; and when the second control is being performed, performs at least one of cut-off control to switch the second switching unit to the second cut-off state when a current flowing through the second power path exceeds a cut-off threshold, and current limit control to control the second switching unit to limit the current flowing through the second power path to equal to or lower than the limit threshold when the current flowing through the second power path exceeds a limit threshold.

[0011] The in-vehicle control device can supply power from the first power supply unit to the load when a start condition is met. Furthermore, when the voltage of the first power path becomes equal to or lower than a threshold voltage while power is being supplied from the first power supply unit to the load, the in-vehicle control device can cut off the power supply from the first power supply unit and supply power from the second power supply unit to the load. Furthermore, by performing at least one of cut-off control and current limiting control while power is being supplied from the second power supply unit to the load, the in-vehicle control device can easily prevent excessive discharge current from the second power supply unit serving as a backup power source.

[0012] [2] The in-vehicle control device according to [1], wherein the second switching unit includes a switch unit and a voltage conversion unit provided in parallel with the switch unit, and the switch unit switches between an ON state in which it allows current to flow from the second power supply unit side to the first power path side through the switch unit and an OFF state in which it blocks current from flowing from the second power supply unit side to the first power path side through the switch unit, the voltage conversion unit performs a voltage conversion operation in which it increases or decreases a voltage input from the second power supply unit side and outputs the voltage to the first power path side, and the control unit, when the voltage of the first power path becomes equal to or lower than the threshold voltage while the first control is being performed, controls the first switching unit to the first block state, controls the switch unit to the ON state, and performs the second control in which the voltage conversion unit performs the voltage conversion operation, and when the current flowing through the second power path exceeds the limit threshold while the second control is being performed, causes the voltage conversion unit to perform the voltage conversion operation so as to suppress the current flowing through the second power path to be equal to or lower than the limit threshold.

[0013] When the voltage of the first power path falls below a threshold voltage while the first control is being performed, the vehicle control device controls the switch unit to an on state, thereby quickly starting power supply from the second power supply unit to the load. Moreover, the vehicle control device controls the voltage conversion unit to perform a voltage conversion operation, thereby controlling the output voltage to the load. Furthermore, when the current flowing through the second power path exceeds a limit threshold while power is being supplied from the second power supply unit to the load, the vehicle control device controls the voltage conversion unit to perform a voltage conversion operation to suppress the current flowing through the second power path to be below the limit threshold. Therefore, the vehicle control device can easily suppress the current flowing from the second power supply unit to the load to be below the limit threshold.

[0014] [3] The vehicle control device described in [2], wherein the control unit switches the switch unit to an off state when the current flowing through the second power path exceeds an overcurrent threshold that is greater than the limit threshold while the second control is being performed.

[0015] In the above-mentioned vehicle control device, when the operation of the voltage conversion unit alone is not sufficient to suppress the current and the current flowing through the second power path exceeds the overcurrent threshold, the current flowing through the second power path can be more reliably suppressed by switching the switch unit to the off state.

[0016] [4] The in-vehicle control device described in [1], wherein the second switching unit includes a switch unit, and when the switch unit is in an on state, the second permissive state is achieved, and when the switch unit is in an off state, the second cut-off state is achieved, and the control unit performs the cut-off control by switching the switch unit to the off state when the current flowing through the second power path exceeds the cut-off threshold while the second control is being performed.

[0017] The in-vehicle control device can quickly start supplying power from the second power supply to the load by controlling the switch unit to the on state when the voltage of the first power path falls below a threshold voltage while the first control is being performed. Furthermore, the in-vehicle control device can more reliably prevent excessive discharge current from the second power supply by switching the switch unit to the off state when the current flowing through the second power path exceeds a cut-off threshold while the second control is being performed.

[0018] [5] The second switching unit includes a voltage conversion unit that performs a voltage conversion operation to boost or lower the voltage input from the second power supply unit side and output it to the first power path side, the voltage conversion unit performing the voltage conversion operation results in the second permissive state, and the voltage conversion unit stopping the voltage conversion operation results in the second cut-off state, and the control unit causes the voltage conversion unit to perform the voltage conversion operation so as to keep the current flowing through the second power path below the limit threshold when the current flowing through the second power path exceeds the limit threshold while the second control is being performed.

[0019] When the voltage of the first power path falls below a threshold voltage while the first control is being performed, the vehicle control device controls the first switching unit to a first cut-off state and causes the voltage conversion unit to perform a voltage conversion operation, thereby controlling the output voltage to the load. Furthermore, when the current flowing through the second power path exceeds a limit threshold while power is being supplied from the second power supply unit to the load, the vehicle control device causes the voltage conversion unit to perform a voltage conversion operation to suppress the current flowing through the second power path below the limit threshold. Therefore, the vehicle control device can easily suppress the current flowing from the second power supply unit to the load below the limit threshold.

[0020] [6] The vehicle control device according to any one of [1] to [5], further comprising an overcurrent prevention unit provided in the first power path, wherein the overcurrent prevention unit prevents an overcurrent from flowing in the first power path.

[0021] While the first control is being performed, there is a risk that the current flowing through the first power path will become an overcurrent if the voltage of the first power path does not fall below the threshold voltage. However, the above-described vehicle control device can prevent an overcurrent from flowing through the first power path by using the overcurrent prevention unit.

[0022] [Details of the embodiment of the present disclosure] 1. First embodiment An in-vehicle system 1 of the first embodiment 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, a load 13, a first power path 14, and a second power path 15.

[0023] The first power supply unit 11 is configured as a DC power supply such as a battery. The second power supply unit 12 is configured as a DC power supply such as a battery. The second power supply unit 12 functions as a backup power supply in the event of a failure of the first power supply unit 11. The output voltage of the second power supply unit 12 when fully charged may be higher or lower than the output voltage of the first power supply unit 11 when fully charged, or may be the same as the output voltage of the first power supply unit 11 when fully charged.

[0024] The first power path 14 includes, for example, a coated wire. The first power path 14 is provided between the first power supply unit 11 and the load 13. Power is supplied from the first power supply unit 11 to the load 13 via the first power path 14. The second power path 15 includes, for example, a coated wire. The second power path 15 is provided between the second power supply unit 12 and the first power path 14. Power is supplied from the second power supply unit 12 to the load 13 via the first power path 14 and the second power path 15.

[0025] The in-vehicle system 1 includes an in-vehicle control device 20. The in-vehicle control device 20 has a first switching unit 21, a second switching unit 22, a voltage detection unit 23, a current detection unit 24, an overcurrent prevention unit 25, and a control unit 26.

[0026] The first switching unit 21 is provided closer to the first power supply unit 11 than the connection portion of the first power path 14 with the second power path 15. The first switching unit 21 switches between a first permissive state in which current is permitted to flow from the first power supply unit 11 to the load 13 and a first blocked state in which current is blocked from flowing from the load 13 to the first power supply unit 11. In this embodiment, the first switching unit 21 permits bidirectional current flow via the first switching unit 21 in the first permissive state and blocks bidirectional current flow via the first switching unit 21 in the first blocked state. The first switching unit 21 includes a first switch unit 21A. The first switch unit 21A may be configured as a mechanical switch or a semiconductor switch. The first switching unit 21 enters the first permissive state when the first switch unit 21A is turned on, and enters the first blocked state when the first switch unit 21A is turned off.

[0027] The second switching unit 22 is provided on the second power path 15. The second switching unit 22 switches between a second permissive state in which current is permitted to flow from the second power supply unit 12 to the first power path 14, and a first blocked state in which current is blocked from flowing from the second power supply unit 12 to the first power path 14. In this embodiment, the second switching unit 22 permits bidirectional current flow via the second switching unit 22 in the second permissive state, and blocks bidirectional current flow via the second switching unit 22 in the second blocked state. The second switching unit 22 includes a second switch unit 22A and a voltage conversion unit 22B.

[0028] The second switch unit 22A may be configured as a mechanical switch or a semiconductor switch. The second switch unit 22A corresponds to an example of a switch unit. The second switch unit 22A switches between an ON state in which it allows current to flow from the second power supply unit 12 to the first power path 14 through itself, and an OFF state in which it blocks current from flowing from the second power supply unit 12 to the first power path 14 through itself. In this embodiment, the second switch unit 22A allows bidirectional current flow through itself in the ON state and blocks bidirectional current flow through itself in the OFF state.

[0029] The voltage conversion unit 22B is provided in parallel with the second switch unit 22A between the second power supply unit 12 and the first power path 14. The voltage conversion unit 22B performs a voltage conversion operation of stepping up or stepping down the voltage input from the second power supply unit 12 side and outputting the voltage to the first power path 14 side. The voltage conversion unit 22B is configured by, for example, a DC-DC converter.

[0030] The second switching unit 22 is in the second permissive state when either the second switch unit 22A is in the on state or the voltage conversion unit 22B is performing a voltage conversion operation is satisfied. The second switching unit 22 is in the second blocked state when the second switch unit 22A is in the off state and the voltage conversion unit 22B is stopped.

[0031] The voltage detection unit 23 detects the voltage of the first power path 14. In the example shown in FIG. 1 , the voltage detection unit 23 detects the voltage on the load 13 side relative to the first switch unit 21A. A signal indicating the value detected by the voltage detection unit 23 is input to the control unit 26. The voltage detection unit 23 is configured as, for example, a known voltage detection circuit.

[0032] The current detection unit 24 detects the current flowing through the second power path 15. A signal indicating the value detected by the current detection unit 24 is input to the control unit 26. The current detection unit 24 is configured by, for example, a known current sensor.

[0033] The overcurrent prevention unit 25 is provided on the first power path 14. The overcurrent prevention unit 25 prevents an overcurrent from flowing through the first power path 14. The overcurrent prevention unit 25 is, for example, a fuse.

[0034] The control unit 26 includes, for example, a microcomputer. The control unit 26 performs a first control when a start condition is met. The first control is a control for controlling the first switching unit 21 to a first permissive state and the second switching unit 22 to a second blocked state. The start condition may be, for example, that a start switch of the vehicle is switched to an on state, or may be another condition. The start switch may be, for example, an ignition switch or a power switch.

[0035] The control unit 26 performs the second control when the voltage of the first power path 14 falls below a predetermined threshold voltage while the first control is being performed. The second control is a control that controls the first switching unit 21 to a first cut-off state and the second switching unit 22 to a second permissive state. The threshold voltage is 0 V or higher. In the second control, the control unit 26 controls the second switch unit 22A to an on state and causes the voltage conversion unit 22B to perform a voltage conversion operation. In the second control, the control unit 26 causes the voltage conversion unit 22B to perform a voltage conversion operation so that the output voltage of the voltage conversion unit 22B becomes a target voltage. The target voltage is a voltage that is equal to or higher than the minimum operating voltage of the load 13 and equal to or lower than the maximum operating voltage of the load 13.

[0036] The control unit 26 performs current limiting control while the second control is being performed. The current limiting control is a control that causes the voltage conversion unit 22B to perform a voltage conversion operation so as to suppress the current flowing through the second power path 15 to be equal to or less than the limiting threshold when the current flowing through the second power path 15 exceeds the limiting threshold.

[0037] When the current flowing through the second power path 15 exceeds an overcurrent threshold that is greater than the limit threshold while the second control is being performed, the control unit 26 switches the second switch unit 22A to the off state while causing the voltage conversion unit 22B to perform a voltage conversion operation so as to keep the current flowing through the second power path 15 below the limit threshold.

[0038] When the above-described start condition is met, the control unit 26 performs, for example, the processing shown in Fig. 2. The control unit 26 starts the first control in step S11 of Fig. 2. While the first control is being performed, the control unit 26 determines in step S12 whether the voltage of the first power path 14 is equal to or less than the threshold voltage. If the control unit 26 determines that the voltage of the first power path 14 is not equal to or less than the threshold voltage, the control unit 26 continues the first control and repeats the processing of step S12 until it determines that the voltage of the first power path 14 is equal to or less than the threshold voltage.

[0039] If the control unit 26 determines that the voltage of the first power path 14 is equal to or lower than the threshold voltage, the control unit 26 ends the first control and starts the second control in step S13. While the second control is being performed, the control unit 26 determines in step S14 whether the current flowing through the second power path 15 has exceeded the limit threshold. If the control unit 26 determines that the current flowing through the second power path 15 has not exceeded the limit threshold, the control unit 26 continues the second control and repeats the processing of step S14 until it determines that the current flowing through the second power path 15 has exceeded the limit threshold.

[0040] If the control unit 26 determines that the current flowing through the second power path 15 has exceeded the limit threshold, then in step S15, the control unit 26 starts suppression control, which causes the voltage conversion unit 22B to perform a voltage conversion operation so as to keep the current flowing through the second power path 15 equal to or less than the limit threshold. While the control unit 26 is performing the suppression control, in step S16, the control unit 26 determines whether the current flowing through the second power path 15 exceeds the overcurrent threshold. If the control unit 26 determines that the current flowing through the second power path 15 has not exceeded the overcurrent threshold, the control unit 26 continues the suppression control and repeats the processing of step S16 until it determines that the current flowing through the second power path 15 has exceeded the overcurrent threshold.

[0041] When the control unit 26 determines that the current flowing through the second power path 15 exceeds the overcurrent threshold, the control unit 26 continues the suppression control and switches the second switch unit 22A to the OFF state. Then, the control unit 26 ends the process shown in FIG. 2 .

[0042] The following description relates to the operation and effects of the in-vehicle control device 20 of the first embodiment. When a start condition is met, the in-vehicle control device 20 can supply power from the first power supply unit 11 to the load 13. Furthermore, when the voltage of the first power path 14 becomes equal to or lower than a threshold voltage while power is being supplied from the first power supply unit 11 to the load 13, the in-vehicle control device 20 can cut off the power supply from the first power supply unit 11 and supply power from the second power supply unit 12 to the load 13. Furthermore, by performing current limiting control while power is being supplied from the second power supply unit 12 to the load 13, the in-vehicle control device 20 can easily prevent excessive discharge current from the second power supply unit 12 serving as a backup power source.

[0043] When the voltage of the first power path 14 falls below the threshold voltage while the first control is being performed, the in-vehicle control device 20 controls the second switch unit 22A to an on state, thereby quickly starting the supply of power from the second power supply unit 12 to the load 13. Moreover, the in-vehicle control device 20 controls the voltage conversion unit 22B to perform a voltage conversion operation, thereby controlling the output voltage to the load 13. Furthermore, when the current flowing through the second power path 15 exceeds the limit threshold while power is being supplied from the second power supply unit 12 to the load 13, the in-vehicle control device 20 controls the voltage conversion unit 22B to perform a voltage conversion operation so as to suppress the current flowing through the second power path 15 to be below the limit threshold. Therefore, the in-vehicle control device 20 can easily suppress the current flowing from the second power supply unit 12 to the load 13 to be below the limit threshold.

[0044] When the operation of the voltage conversion unit 22B alone is not sufficient to suppress the current, and the current flowing through the second power path 15 exceeds the overcurrent threshold, the vehicle control device 20 can more reliably suppress the current flowing through the second power path 15 by switching the second switch unit 22A to the off state.

[0045] While the first control is being performed, there is a risk that the voltage of the first power path 14 will not fall below the threshold voltage, and the current flowing through the first power path 14 will become an overcurrent. However, the on-board control device 20 can prevent an overcurrent from flowing through the first power path 14 by using the overcurrent prevention unit 25.

[0046] 2. Second Embodiment In the second embodiment, an example will be described in which the second switching unit is configured only by a second switch unit. 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.

[0047] 3 , the in-vehicle system 201 of the second embodiment includes a first power supply unit 11, a second power supply unit 12, a load 13, a first power path 14, and a second power path 15. The in-vehicle system 201 includes an in-vehicle control device 220.

[0048] The in-vehicle control device 220 includes a first switching unit 21 , a second switching unit 222 , a voltage detection unit 23 , a current detection unit 24 , an overcurrent prevention unit 25 , and a control unit 26 .

[0049] The second switching unit 222 includes only the second switch unit 22A. The second switching unit 222 differs from the second switching unit 22 of the first embodiment in that it does not include the voltage conversion unit 22B, but is otherwise the same. The second switching unit 222 enters a second permissive state when the second switch unit 22A is turned on, and enters a second blocked state when the second switch unit 22A is turned off.

[0050] The control unit 26 performs a first control when a start condition is met. In the first control, the control unit 26 controls the first switch unit 21A to an ON state and the second switch unit 22A to an OFF state. In the first control, the control unit 26 performs a second control when the voltage of the first power path 14 becomes equal to or lower than a threshold voltage while the first control is being performed. In the second control, the control unit 26 controls the first switch unit 21A to an OFF state and the second switch unit 22A to an ON state. In the second control, the control unit 26 performs a cutoff control by switching the second switch unit 22A to an OFF state when the current flowing through the second power path 15 exceeds a cutoff threshold while the second control is being performed.

[0051] When the above-described start condition is met, the control unit 26 performs, for example, the processing shown in Fig. 4 . The control unit 26 starts the first control in step S21 of Fig. 4 . While the first control is being performed, the control unit 26 determines in step S22 whether the voltage of the first power path 14 is equal to or lower than the threshold voltage. If the control unit 26 determines that the voltage of the first power path 14 is not equal to or lower than the threshold voltage, the control unit 26 continues the first control and repeats the processing of step S22 until it determines that the voltage of the first power path 14 is equal to or lower than the threshold voltage.

[0052] If the control unit 26 determines that the voltage of the first power path 14 is equal to or lower than the threshold voltage, the control unit 26 ends the first control and starts the second control in step S23. While the second control is being performed, the control unit 26 determines in step S24 whether the current flowing through the second power path 15 has exceeded the cut-off threshold. If the control unit 26 determines that the current flowing through the second power path 15 has not exceeded the cut-off threshold, the control unit 26 continues the second control and repeats the processing of step S24 until it determines that the current flowing through the second power path 15 has exceeded the cut-off threshold.

[0053] If the control unit 26 determines that the current flowing through the second power path 15 exceeds the interruption threshold, the control unit 26 switches the second switch unit 22A to the OFF state in step S25. Thereafter, the control unit 26 ends the process shown in FIG. 4 .

[0054] The in-vehicle control device 220 of the second embodiment can quickly start supplying power from the second power supply unit 12 to the load 13 by controlling the second switch unit 22A to the ON state when the voltage of the first power path 14 becomes equal to or lower than the threshold voltage while the first control is being performed. Furthermore, the in-vehicle control device 220 can more reliably prevent the discharge current from the second power supply unit 12 from becoming excessive by switching the second switch unit 22A to the OFF state when the current flowing through the second power path 15 exceeds the cut-off threshold while the second control is being performed.

[0055] 3. Third Embodiment In the third embodiment, an example will be described in which the second switching unit is configured only by a voltage conversion unit. Note that 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.

[0056] 5 , an in-vehicle system 301 according to the third embodiment includes a first power supply unit 11, a second power supply unit 12, a load 13, a first power path 14, and a second power path 15. The in-vehicle system 301 includes an in-vehicle control device 320.

[0057] The in-vehicle control device 320 includes a first switching unit 21 , a second switching unit 322 , a voltage detection unit 23 , a current detection unit 24 , an overcurrent prevention unit 25 , and a control unit 26 .

[0058] The second switching unit 322 includes only the voltage conversion unit 22B. The second switching unit 322 differs from the second switching unit 22 of the first embodiment in that it does not include the second switch unit 22A, but is otherwise the same. The second switching unit 322 enters a second permissive state when the voltage conversion unit 22B performs a voltage conversion operation, and enters a second blocked state when the voltage conversion unit 22B stops the voltage conversion operation.

[0059] The control unit 26 performs a first control when a start condition is met. In the first control, the control unit 26 controls the first switch unit 21A to an ON state and the second switch unit 22A to an OFF state. In the second control, when the voltage of the first power path 14 becomes equal to or lower than a threshold voltage while the first control is being performed, the control unit 26 performs a second control. In the second control, the control unit 26 controls the first switch unit 21A to an OFF state and causes the voltage conversion unit 22B to perform a voltage conversion operation. In the second control, the control unit 26 causes the voltage conversion unit 22B to perform a voltage conversion operation so that the output voltage of the voltage conversion unit 22B becomes a target voltage. The target voltage is a voltage equal to or higher than the minimum operating voltage of the load 13 and equal to or lower than the maximum operating voltage of the load 13. When the current flowing through the second power path 15 exceeds the limit threshold while the second control is being performed, the control unit 26 causes the voltage conversion unit 22B to perform a voltage conversion operation so as to keep the current flowing through the second power path 15 below the limit threshold.

[0060] When the above-described start condition is met, the control unit 26 performs, for example, the processing shown in Fig. 6 . The control unit 26 starts the first control in step S31 of Fig. 6 . While the first control is being performed, the control unit 26 determines in step S32 whether the voltage of the first power path 14 is equal to or less than the threshold voltage. If the control unit 26 determines that the voltage of the first power path 14 is not equal to or less than the threshold voltage, the control unit 26 continues the first control and repeats the processing of step S32 until it determines that the voltage of the first power path 14 is equal to or less than the threshold voltage.

[0061] If the control unit 26 determines that the voltage of the first power path 14 is equal to or lower than the threshold voltage, the control unit 26 ends the first control and starts the second control in step S33. While the second control is being performed, the control unit 26 determines in step S34 whether the current flowing through the second power path 15 has exceeded the limit threshold. If the control unit 26 determines that the current flowing through the second power path 15 has not exceeded the limit threshold, the control unit 26 continues the second control and repeats the processing of step S34 until it determines that the current flowing through the second power path 15 has exceeded the limit threshold.

[0062] When the control unit 26 determines that the current flowing through the second power path 15 exceeds the limit threshold, the control unit 26 starts suppression control in step S35. After that, the control unit 26 ends the process shown in FIG.

[0063] The in-vehicle control device 320 of the third embodiment can control the output voltage to the load 13 by controlling the first switching unit 21 to the first cut-off state and causing the voltage conversion unit 22B to perform a voltage conversion operation when the voltage of the first power path 14 falls below the threshold voltage while performing the first control. Furthermore, when the current flowing through the second power path 15 exceeds the limit threshold while power is being supplied from the second power supply unit 12 to the load 13, the in-vehicle control device 320 causes the voltage conversion unit 22B to perform a voltage conversion operation to suppress the current flowing through the second power path 15 to be below the limit threshold. Therefore, the in-vehicle control device 320 can easily suppress the current flowing from the second power supply unit 12 to the load 13 to be below the limit threshold.

[0064] <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.

[0065] In the above embodiment, an example was described in which the processes shown in Figures 2, 4, and 6 are performed by a microcomputer, but some or all of the processes shown in Figures 2, 4, and 6 may be performed by a control circuit other than a microcomputer.

[0066] 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.

[0067] REFERENCE SIGNS LIST 1...In-vehicle system 11...First power supply unit 12...Second power supply unit 13...Load 14...First power path 15...Second power path 20...In-vehicle control device 21...First switching unit 21A...First switch unit 22...Second switching unit 22A...Second switch unit (switch unit) 22B...Voltage conversion unit 23...Voltage detection unit 24...Current detection unit 25...Overcurrent prevention unit 26...Control unit 201...In-vehicle system 220...In-vehicle control device 222...Second switching unit 301...In-vehicle system 320...In-vehicle control device 322...Second switching unit

Claims

1. An in-vehicle control device included in an in-vehicle system comprising a first power supply unit, a load, a first power path provided between the first power supply unit and the load, a second power supply unit, and a second power path provided between the second power supply unit and the first power path; a first switching unit provided on the first power supply unit side rather than the connection portion of the first power path with the second power path; a second switching unit provided on the second power path; and a control unit that controls the first switching unit and the second switching unit, wherein the first switching unit switches between a first allowable state that allows current to flow from the first power supply unit side to the load side and a first blocking state that blocks current from flowing from the load side to the first power supply unit side, the second switching unit switches between a second allowable state that allows current to flow from the second power supply unit side to the first power path side and a second blocking state that blocks current from flowing from the second power supply unit side to the first power path side, and the control unit performs a first control that controls the first switching unit to the first allowable state and the second switching unit to the second blocking state when a start condition is satisfied, performs a second control that controls the first switching unit to the first blocking state and the second switching unit to the second allowable state when the voltage of the first power path becomes equal to or lower than a threshold voltage while the first control is being performed, and performs at least one of a blocking control that switches the second switching unit to the second blocking state when the current flowing through the second power path exceeds a blocking threshold value and a current limiting control that controls the second switching unit so as to suppress the current flowing through the second power path to be equal to or lower than a limit threshold value when the current flowing through the second power path exceeds the limit threshold value in a state where the second control is being performed.

2. The second switching unit includes a switch unit and a voltage conversion unit provided in parallel with the switch unit. The switch unit switches between an on state that allows current to flow from the second power supply unit side to the first power path side through itself and an off state that blocks current from flowing from the second power supply unit side to the first power path side through itself. The voltage conversion unit performs a voltage conversion operation of boosting or bucking the voltage input from the second power supply unit side and outputting it to the first power path side. When the voltage of the first power path becomes equal to or lower than the threshold voltage while the control unit is performing the first control, the control unit controls the first switching unit to the first cutoff state, controls the switch unit to the on state, and performs the second control to cause the voltage conversion unit to perform the voltage conversion operation. When the current flowing through the second power path exceeds the limit threshold while the second control is being performed, the control unit causes the voltage conversion unit to perform the voltage conversion operation so as to suppress the current flowing through the second power path to be equal to or lower than the limit threshold. The in-vehicle control device according to claim 1.

3. When the current flowing through the second power path exceeds an overcurrent threshold greater than the limit threshold while the control unit is performing the second control, the control unit switches the switch unit to the off state. The in-vehicle control device according to claim 2.

4. The second switching unit includes a switch unit. When the switch unit is in the on state, the second allowable state is reached, and when the switch unit is in the off state, the second cutoff state is reached. When the current flowing through the second power path exceeds the cutoff threshold while the control unit is performing the second control, the control unit performs the cutoff control of switching the switch unit to the off state. The in-vehicle control device according to claim 1.

5. The second switching unit includes a voltage conversion unit that performs a voltage conversion operation of boosting or bucking the voltage input from the second power supply unit side and outputting it to the first power path side. When the voltage conversion unit performs the voltage conversion operation, the second allowable state is reached, and when the voltage conversion unit stops the voltage conversion operation, the second cutoff state is reached. When the current flowing through the second power path exceeds the limit threshold while the control unit is performing the second control, the control unit causes the voltage conversion unit to perform the voltage conversion operation so as to suppress the current flowing through the second power path to be equal to or lower than the limit threshold. The in-vehicle control device according to claim 1.

6. The in-vehicle control device according to any one of claims 1 to 5, having an overcurrent prevention unit provided in the first power path, the overcurrent prevention unit preventing an overcurrent from flowing through the first power path.

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