In-vehicle control device

Abstract

A control device (20) for a vehicle has a first switching section (21), a second switching section (22), and a control section (26). The control section (26) performs first control that controls the first switching section (21) to a first allowed state and controls the second switching section (22) to a second cut-off state. When a voltage of a first power path (14) becomes below a threshold voltage in a state where the first control is performed, the control section (26) performs second control that controls the first switching section (21) to a first cut-off state and controls the second switching section (22) to a second allowed state. In a state where the second control is performed, the control section (26) performs at least one of cut-off control that switches the second switching section (22) to a second cut-off state when a current flowing through a second power path (15) exceeds a cut-off threshold value and current limit control that controls the second switching section (22) to suppress the current flowing through the second power path (15) to be below a limit threshold value when the current flowing through the second power path (15) exceeds the limit threshold value.

Description

Technical Field

[0001] This disclosure relates to vehicle-mounted control devices. Background Technology

[0002] Patent Document 1 discloses a vehicle-mounted backup power control device. This backup power control device discharges an energy storage unit to a load when the power supply to the power source fails. The backup power control device determines that the power supply to the power source has failed when the voltage of the first conductive path between the power source and the load falls below a predetermined first threshold voltage. Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-092476. Summary of the Invention The problem that the invention aims to solve

[0004] In the structure of Patent Document 1, even if the cause is on the load side, such as a load-to-ground short circuit, it is still determined that the power supply of the power source has failed. In this case, if the energy storage unit discharges to the load, the discharge current from the energy storage unit to the load may exceed the intended current value.

[0005] The purpose of this disclosure is to provide a technique for easily suppressing excessive discharge current from a backup power source. Methods for solving problems

[0006] The vehicle-mounted control device disclosed herein includes a vehicle-mounted system, the vehicle-mounted system comprising a first power supply unit, a load, a first power path disposed between the first power supply unit and the load, a second power supply unit, and a second power path disposed between the second power supply unit and the first power path. The vehicle-mounted control device has the following features: The first switching unit is located in the first power path at a position closer to the first power source than the connection portion of the second power path. A second switching unit is located in the second power path; and The control unit controls the first switching unit and the second switching unit. The first switching unit switches between a first permitted state that allows current to flow from the first power supply side to the load side and a first interrupted state that cuts off current flow from the load side to the first power supply side. The second switching unit switches between a second permitted state, which allows current to flow from the second power source side to the first power path side, and a second interrupted state, which interrupts current flow from the second power source side to the first power path side. When the start condition is met, the control unit performs a first control, setting the first switching unit to the first permitted state and the second switching unit to the second cut-off state. When the voltage of the first power path falls below a threshold voltage while the first control is in effect, the control unit performs a second control, setting the first switching unit to the first disconnect state and the second switching unit to the second allow state. When the second control is performed, the control unit performs at least one of cut-off control and current limiting control. The cut-off control is the control that switches the second switching unit to the second cut-off state when the current flowing through the second power path exceeds the cut-off threshold. The current limiting control is the control that controls the second switching unit to suppress the current flowing through the second power path to below the limit threshold when the current flowing through the second power path exceeds the limit threshold. Invention Effects

[0007] According to the technology disclosed herein, it is easy to suppress excessive discharge current from the backup power supply. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the structure of an onboard system including the onboard control device of the first embodiment. Figure 2 This is a flowchart of the processing performed by the control unit in the first embodiment. Figure 3 This is a schematic diagram of the structure of an onboard system including the onboard control device of the second embodiment. Figure 4 This is a flowchart of the processing performed by the control unit in the second embodiment. Figure 5 This is a schematic diagram of the structure of an in-vehicle system including the in-vehicle control device of the third embodiment. Figure 6 This is a flowchart of the processing performed by the control unit in the third embodiment. Detailed Implementation

[0009] [Description of embodiments of this disclosure] The following are examples and illustrations of the embodiments involved in this disclosure.

[0010] [1] A vehicle-mounted control device, comprising a vehicle-mounted system, the vehicle-mounted system including a first power supply unit, a load, a first power path disposed between the first power supply unit and the load, a second power supply unit, and a second power path disposed between the second power supply unit and the first power path. The vehicle-mounted control device has the following features: The first switching unit is located in the first power path at a position closer to the first power source than the connection portion of the second power path. A second switching unit is located in the second power path; and The control unit controls the first switching unit and the second switching unit. The first switching unit switches between a first permitted state that allows current to flow from the first power supply side to the load side and a first interrupted state that cuts off current flow from the load side to the first power supply side. The second switching unit switches between a second permitted state, which allows current to flow from the second power source side to the first power path side, and a second interrupted state, which interrupts current flow from the second power source side to the first power path side. When the start condition is met, the control unit performs a first control, setting the first switching unit to the first permitted state and the second switching unit to the second cut-off state. When the voltage of the first power path falls below a threshold voltage while the first control is in effect, the control unit performs a second control, setting the first switching unit to the first disconnect state and the second switching unit to the second allow state. When the second control is performed, the control unit performs at least one of cut-off control and current limiting control; the cut-off control is as follows: when the current flowing through the second power path exceeds the cut-off threshold, the second switching unit is switched to the second cut-off state; the current limiting control is as follows: when the current flowing through the second power path exceeds the limiting threshold, the second switching unit is controlled to suppress the current flowing through the second power path to below the limiting threshold.

[0011] When the start conditions are met, the aforementioned vehicle-mounted control device can supply power from the first power source to the load. Furthermore, when the voltage of the first power path falls below a threshold voltage while power is being supplied from the first power source to the load, the vehicle-mounted control device can cut off the power supply from the first power source and supply power from the second power source to the load. Moreover, by performing at least one of cutoff control and current limiting control while power is being supplied from the second power source to the load, the vehicle-mounted control device can easily suppress excessive discharge current from the second power source, which serves as a backup power source.

[0012] [2] According to the vehicle-mounted control device described in [1], wherein, The second switching unit includes a switching unit and a voltage conversion unit arranged in parallel with the switching unit. The switching unit switches between a conducting state, which allows current to flow from the second power source side to the first power path side via itself, and a disconnecting state, which prevents current from flowing from the second power source side to the first power path side via itself. The voltage conversion unit performs a voltage conversion operation, boosting or bucking the voltage input from the second power supply side and outputting it to the first power path side. When the voltage of the first power path is below the threshold voltage while the first control is in effect, the control unit performs the second control, which controls the first switching unit to the first off state, controls the switching unit to the on state, and causes 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 in effect, the control unit causes the voltage conversion unit to perform the voltage conversion operation to suppress the current flowing through the second power path to be below the limit threshold.

[0013] When the voltage of the first power path falls below a threshold voltage during the first control state, the aforementioned vehicle-mounted control device can quickly begin supplying power from the second power source to the load by controlling the switch to the on state. Furthermore, the vehicle-mounted control device can control the voltage output to the load by performing a voltage conversion operation on the voltage conversion unit. Additionally, when the current flowing through the second power path exceeds a limit threshold while power is being supplied from the second power source to the load, the vehicle-mounted control device performs a voltage conversion operation on the voltage conversion unit to suppress the current flowing through the second power path to below the limit threshold. Therefore, the aforementioned vehicle-mounted control device easily suppresses the current flowing from the second power source to the load to below the limit threshold.

[0014] [3] According to the vehicle-mounted control device described in [2], wherein, When the current flowing through the second power path exceeds an overcurrent threshold greater than the limit threshold while the second control is in effect, the control unit switches the switch to the off state.

[0015] When the operation of the voltage conversion unit alone is insufficient to suppress the current, causing the current flowing through the second power path to exceed the overcurrent threshold, the above-mentioned vehicle control device can more reliably suppress the current flowing through the second power path by switching the switch unit to the off state.

[0016] [4] According to the vehicle-mounted control device described in [1], wherein, The second switching unit includes a switch section. By turning the switch section to an ON state, the second switching unit enters a second ON state; by turning the switch section to an OFF state, the second switching unit enters a second OFF state. When the current flowing through the second power path exceeds the cut-off threshold while the second control is in effect, the control unit performs the cut-off control to switch the switch unit to the off state.

[0017] When the voltage of the first power path falls below a threshold voltage during the first control state, the aforementioned vehicle-mounted control device can quickly begin supplying power from the second power source to the load by controlling the switch to the on state. Furthermore, when the current flowing through the second power path exceeds a cutoff threshold during the second control state, the aforementioned vehicle-mounted control device can more reliably suppress excessive discharge current from the second power source by switching the switch to the off state.

[0018] [5] According to the vehicle-mounted control device described in [1], wherein, The second switching unit includes a voltage conversion unit that performs a voltage conversion operation on the voltage input from the second power supply side, either boosting or bucking it before outputting it to the first power path side. When the voltage conversion operation is performed by the voltage conversion unit, the second switching unit enters a second enabled state; when the voltage conversion operation is stopped by the voltage conversion unit, the second switching unit enters a second disabled state. When the current flowing through the second power path exceeds the limit threshold while the second control is in effect, the control unit causes the voltage conversion unit to perform the voltage conversion operation to suppress the current flowing through the second power path to below the limit threshold.

[0019] When the voltage of the first power path falls below a threshold voltage during the first control state, the aforementioned vehicle-mounted control device can control the voltage output to the load by controlling the first switching unit to a first cut-off state and causing the voltage conversion unit to perform a voltage conversion operation. Furthermore, when the aforementioned vehicle-mounted control device is supplying power from the second power source to the load, and the current flowing through the second power path exceeds a limit threshold, it causes the voltage conversion unit to perform a voltage conversion operation to suppress the current flowing through the second power path to below the limit threshold. Therefore, the aforementioned vehicle-mounted control device easily suppresses the current flowing from the second power source to the load to below the limit threshold.

[0020] [6] The vehicle-mounted control device according to any one of [1] to [5], wherein, The vehicle-mounted control device includes an overcurrent prevention unit located in the first power path. The overcurrent prevention unit prevents overcurrent from flowing through the first power path.

[0021] In the first control state, it is possible that the current flowing through the first power path may become an overcurrent even if the voltage of the first power path is not below the threshold voltage. However, the above-mentioned vehicle control device can prevent overcurrent from flowing through the first power path by means of an overcurrent prevention unit.

[0022] <Details of the embodiments disclosed> 1. First Implementation Method The vehicle system 1 of the first embodiment is a system mounted on a vehicle. The 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, for example, as a DC power source such as a storage battery. The second power supply unit 12 is configured, for example, as a DC power source such as a storage battery. The second power supply unit 12 functions as a backup power source when the first power supply unit 11 fails. The output voltage of the second power supply unit 12 when fully charged may be higher than, lower than, or the same as the output voltage of the first power supply unit 11 when fully charged.

[0024] The first power path 14 is configured, for example, to include a sheathed wire. The first power path 14 is located between the first power source 11 and the load 13. Power is supplied from the first power source 11 to the load 13 via the first power path 14. The second power path 15 is configured, for example, to include a sheathed wire. The second power path 15 is located between the second power source 12 and the first power path 14. Power is supplied from the second power source 12 to the load 13 via both the first power path 14 and the second power path 15.

[0025] The vehicle system 1 includes a vehicle control device 20. The 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 located in the first power path 14 at a position closer to the first power supply unit 11 than the connection portion with the second power path 15. The first switching unit 21 switches between a first permitted state, allowing current to flow from the first power supply unit 11 to the load 13, and a first interrupted state, cutting off current flow from the load 13 to the first power supply unit 11. In this embodiment, when the first switching unit 21 is in the first permitted state, bidirectional current flow through the first switching unit 21 is allowed; when the first switching unit 21 is in the first interrupted state, bidirectional current flow through the first switching unit 21 is interrupted. The first switching unit 21 includes a first switch unit 21A. The first switch unit 21A can be a mechanical switch or a semiconductor switch. By turning the first switch unit 21A into a conducting state, the first switching unit 21 is in the first permitted state; by turning the first switch unit 21A into a disconnected state, the first switching unit 21 is in the first interrupted state.

[0027] A second switching unit 22 is provided in the second power path 15. The second switching unit 22 switches between a second permitted state, allowing current to flow from the second power supply unit 12 side to the first power path 14 side, and a first cut-off state, cutting off current flow from the second power supply unit 12 side to the first power path 14 side. In this embodiment, when the second switching unit 22 is in the second permitted state, bidirectional current flow is allowed through the second switching unit 22; when the second switching unit 22 is in the second cut-off state, bidirectional current flow is cut off through the second switching unit 22. The second switching unit 22 includes a second switching unit 22A and a voltage conversion unit 22B.

[0028] The second switching unit 22A can be configured as a mechanical switch or a semiconductor switch. The second switching unit 22A is an example of a switching unit. The second switching unit 22A switches between a conducting state, which allows current to flow from the second power supply unit 12 side to the first power path 14 side via itself, and a disconnecting state, which cuts off the flow of current from the second power supply unit 12 side to the first power path 14 side via itself. In this embodiment, when the second switching unit 22A is in the conducting state, it allows bidirectional current flow via itself; when the second switching unit 22A is in the disconnecting state, it cuts off the bidirectional current flow via itself.

[0029] The voltage conversion unit 22B is connected in parallel with respect to 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, boosting or bucking the voltage input from the second power supply unit 12 and outputting it to the first power path 14. The voltage conversion unit 22B is, for example, a DC-DC converter.

[0030] When either the second switch 22A is in the ON state or the voltage conversion unit 22B is performing a voltage conversion operation, the second switching unit 22 enters the second enabled state. When the second switch 22A is in the OFF state and the voltage conversion unit 22B stops, the second switching unit 22 enters the second ON state.

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

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

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

[0034] The control unit 26 is configured to include, for example, a microcomputer. When the start condition is met, the control unit 26 performs a first control. The first control is to control the first switching unit 21 to a first enabled state and the second switching unit 22 to a second disabled state. The start condition may be, for example, the vehicle's start switch being switched to the ON state, or other conditions. The start switch may be, for example, an ignition switch, a power switch, etc.

[0035] When the voltage of the first power path 14 falls below a preset threshold voltage while the first control is in effect, the control unit 26 performs a second control. The second control involves controlling the first switching unit 21 to a first off state and the second switching unit 22 to a second enabled state. The threshold voltage is 0V or higher. In the second control, the control unit 26 controls the second switching unit 22A to a conducting state and causes the voltage conversion unit 22B to perform a voltage conversion operation. 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 the target voltage. The target voltage is a voltage that is above the minimum operating voltage of the load 13 and below the maximum operating voltage of the load 13.

[0036] The control unit 26 performs current limiting control while performing the second control. The current limiting control is as follows: when the current flowing through the second power path 15 exceeds the limiting threshold, the voltage conversion unit 22B performs a voltage conversion operation to suppress the current flowing through the second power path 15 to below the limiting threshold.

[0037] When the control unit 26 is in the state of performing the second control, if the current flowing through the second power path 15 exceeds the overcurrent threshold which is greater than the limit threshold, it causes the voltage conversion unit 22B to perform a voltage conversion operation to suppress the current flowing through the second power path 15 to below the limit threshold, and switches the second switch unit 22A to the off state.

[0038] When the above-mentioned starting conditions are met, the control unit 26, for example, performs... Figure 2 The process shown is as follows. Control unit 26 in... Figure 2 In step S11, the first control begins. While performing the first control, the control unit 26 determines in step S12 whether the voltage of the first power path 14 is below a threshold voltage. If the control unit 26 determines that the voltage of the first power path 14 is not below the threshold voltage, it continues to perform the first control and repeats step S12 until it determines that the voltage of the first power path 14 is below the threshold voltage.

[0039] When the control unit 26 determines that the voltage of the first power path 14 is below a threshold voltage, it terminates the first control and begins the second control in step S13. While performing the second control, the control unit 26 determines in step S14 whether the current flowing through the second power path 15 exceeds a limit threshold. When the control unit 26 determines that the current flowing through the second power path 15 does not exceed the limit threshold, it continues to perform the second control and repeats step S14 until it determines that the current flowing through the second power path 15 exceeds the limit threshold.

[0040] When the control unit 26 determines that the current flowing through the second power path 15 exceeds the limit threshold, it initiates suppression control in step S15 by causing the voltage conversion unit 22B to perform a voltage conversion operation to suppress the current flowing through the second power path 15 to below the limit threshold. While performing suppression control, the control unit 26 determines in step S16 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 does not exceed the overcurrent threshold, it continues to perform suppression control and repeats step S16 until it determines that the current flowing through the second power path 15 exceeds the overcurrent threshold.

[0041] When the control unit 26 determines that the current flowing through the second power path 15 exceeds the overcurrent threshold, it continues to perform suppression control and switches the second switch unit 22A to the off state. Afterwards, the control unit 26 terminates the operation. Figure 2 The processing is shown.

[0042] The following description relates to the function and effect of the vehicle-mounted control device 20 of the first embodiment. When the starting conditions are met, the 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 falls below a threshold voltage while power is being supplied from the first power supply unit 11 to the load 13, the 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. Moreover, the vehicle control device 20 performs current limiting control while power is being supplied from the second power supply unit 12 to the load 13, thereby easily suppressing excessive discharge current from the second power supply unit 12, which serves as a backup power source.

[0043] When the voltage of the first power path 14 falls below a threshold voltage during the first control state, the vehicle control device 20 can quickly begin supplying power from the second power supply unit 12 to the load 13 by controlling the second switch unit 22A to the conducting state. Furthermore, the vehicle control device 20 can control the voltage output to the load 13 by causing the voltage conversion unit 22B to perform a voltage conversion operation. Additionally, when the current flowing through the second power path 15 exceeds a limit threshold while power is being supplied from the second power supply unit 12 to the load 13, the vehicle control device 20 causes the voltage conversion unit 22B to perform a voltage conversion operation to suppress the current flowing through the second power path 15 to below the limit threshold. Therefore, the vehicle control device 20 easily suppresses the current flowing from the second power supply unit 12 to the load 13 to below the limit threshold.

[0044] When the operation of the voltage conversion unit 22B alone is insufficient to suppress the current, causing the current flowing through the second power path 15 to exceed 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] In the first control state, it is possible that the current flowing through the first power path 14 may become an overcurrent if the voltage of the first power path 14 is not below the threshold voltage. However, the vehicle control device 20 can prevent the overcurrent from flowing through the first power path 14 by using the overcurrent prevention unit 25.

[0046] 2. Second Implementation Method In the second embodiment, an example in which the second switching unit is composed solely of the second switching unit will be described. Furthermore, in the second embodiment, structures identical to those in the first embodiment are labeled with the same reference numerals, and detailed descriptions are omitted.

[0047] like Figure 3 As shown, the 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 vehicle system 201 includes a vehicle control device 220.

[0048] The vehicle-mounted 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 switching 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 they are otherwise the same. By turning the second switching unit 22A into a conducting state, the second switching unit 222 becomes a second enabled state; by turning the second switching unit 22A into a disconnected state, the second switching unit 222 becomes a second disconnected state.

[0050] When the start conditions are met, control unit 26 performs first control. In the first control, control unit 26 controls the first switch 21A to the on state and the second switch 22A to the off state. When the voltage of the first power path 14 falls below a threshold voltage while the first control is in effect, control unit 26 performs second control. In the second control, control unit 26 controls the first switch 21A to the off state and the second switch 22A to the on state. When the current flowing through the second power path 15 exceeds a cutoff threshold while the second control is in effect, control unit 26 performs cutoff control, switching the second switch 22A to the off state.

[0051] When the above-mentioned starting conditions are met, the control unit 26, for example, performs... Figure 4 The process shown is as follows. Control unit 26 in... Figure 4 In step S21, the first control begins. While performing the first control, the control unit 26 determines in step S22 whether the voltage of the first power path 14 is below a threshold voltage. If the control unit 26 determines that the voltage of the first power path 14 is not below the threshold voltage, it continues to perform the first control and repeats step S22 until it determines that the voltage of the first power path 14 is below the threshold voltage.

[0052] When the control unit 26 determines that the voltage of the first power path 14 is below a threshold voltage, it ends the first control and starts the second control in step S23. While the second control is in progress, in step S24, it determines whether the current flowing through the second power path 15 exceeds a cutoff threshold. When the control unit 26 determines that the current flowing through the second power path 15 does not exceed the cutoff threshold, it continues the second control and repeats step S24 until it determines that the current flowing through the second power path 15 exceeds the cutoff threshold.

[0053] When the control unit 26 determines that the current flowing through the second power path 15 exceeds the cutoff threshold, it switches the second switch unit 22A to the off state in step S25. Afterwards, the control unit 26 terminates the process. Figure 4 The processing is shown.

[0054] In the second embodiment, when the voltage of the first power path 14 falls below a threshold voltage during the first control state, the vehicle-mounted control device 220 can quickly begin supplying power from the second power supply unit 12 to the load 13 by controlling the second switch unit 22A to the on state. Furthermore, when the current flowing through the second power path 15 exceeds a cutoff threshold during the second control state, the vehicle-mounted control device 220 can more reliably suppress excessive discharge current from the second power supply unit 12 by switching the second switch unit 22A to the off state.

[0055] 3. Third Implementation Method In the third embodiment, an example in which the second switching unit consists solely of a voltage conversion unit will be described. Furthermore, in the third embodiment, structures identical to those in the first embodiment are labeled with the same reference numerals, and detailed descriptions are omitted.

[0056] like Figure 5 As shown, the vehicle system 301 of 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 vehicle system 301 includes a vehicle control device 320.

[0057] The vehicle-mounted 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 they are otherwise the same. When the voltage conversion unit 22B performs a voltage conversion operation, the second switching unit 322 enters a second enabled state; when the voltage conversion unit 22B stops the voltage conversion operation, the second switching unit 322 enters a second disabled state.

[0059] When the starting conditions are met, control unit 26 performs first control. In the first control, control unit 26 controls first switch 21A to the on state and second switch 22A to the off state. When the voltage of the first power path 14 falls below a threshold voltage while performing the first control, control unit 26 performs second control. In the second control, control unit 26 controls first switch 21A to the off state and causes voltage conversion unit 22B to perform voltage conversion. In the second control, control unit 26 causes voltage conversion unit 22B to perform voltage conversion so that its output voltage becomes the target voltage. The target voltage is a voltage above the minimum operating voltage of load 13 and below the maximum operating voltage of load 13. When the current flowing through the second power path 15 exceeds a limit threshold while performing the second control, control unit 26 causes voltage conversion unit 22B to perform voltage conversion to suppress the current flowing through the second power path 15 to below the limit threshold.

[0060] When the above-mentioned starting conditions are met, the control unit 26, for example, performs... Figure 6 The process shown is as follows. Control unit 26 in... Figure 6 In step S31, the first control begins. While performing the first control, the control unit 26 determines in step S32 whether the voltage of the first power path 14 is below a threshold voltage. If the control unit 26 determines that the voltage of the first power path 14 is not below the threshold voltage, it continues to perform the first control and repeats step S32 until it determines that the voltage of the first power path 14 is below the threshold voltage.

[0061] When the control unit 26 determines that the voltage of the first power path 14 is below a threshold voltage, it ends the first control and starts the second control in step S33. While the second control is in progress, in step S34, it determines whether the current flowing through the second power path 15 exceeds a limit threshold. When the control unit 26 determines that the current flowing through the second power path 15 does not exceed the limit threshold, it continues the second control and repeats step S34 until it determines that the current flowing through the second power path 15 exceeds the limit threshold.

[0062] When the control unit 26 determines that the current flowing through the second power path 15 exceeds the limit threshold, it initiates suppression control in step S35. Afterwards, the control unit 26 terminates... Figure 6 The processing is shown.

[0063] In the third embodiment, when the voltage of the first power path 14 falls below a threshold voltage during the first control state, the vehicle control device 320 controls the voltage output to the load 13 by controlling the first switching unit 21 to a first cut-off state and causing the voltage conversion unit 22B to perform a voltage conversion operation. Furthermore, when the vehicle control device 320 is supplying power from the second power supply unit 12 to the load 13 and the current flowing through the second power path 15 exceeds a limit threshold, the voltage conversion unit 22B performs a voltage conversion operation to suppress the current flowing through the second power path 15 to below the limit threshold. Therefore, the vehicle control device 320 easily suppresses the current flowing from the second power supply unit 12 to the load 13 to below the limit threshold.

[0064] <Other Implementation Methods> This disclosure is not limited to the embodiments described above and in the accompanying drawings. For example, the features of the embodiments described above or later can be combined in all possible ways without contradiction. Furthermore, any feature of the embodiments described above or later may be omitted unless explicitly stated as essential. Moreover, the embodiments described above may also be modified as follows.

[0065] The above embodiments illustrate the use of a microcomputer. Figure 2 , Figure 4 , Figure 6 The example shown is of processing, but Figure 2 , Figure 4 , Figure 6 The processing shown may be performed, in part or in part, by control circuitry other than a microcomputer.

[0066] Furthermore, the embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of this invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope expressed by the claims or their equivalents. Explanation of reference numerals in the attached figures

[0067] 1…In-vehicle system 11…First Power Supply Section 12…Second Power Supply Section 13…load 14…First power path 15…Second power path 20…Vehicle-mounted control devices 21…First Switching Section 21A…First Switch Section 22…Second Switching Section 22A…Second Switch Section (Switch Section) 22B…Voltage Conversion Section 23…Voltage Detection Section 24… Current Detection Section 25…Overcurrent Prevention Section 26…Control Department 201…In-vehicle system 220…Vehicle-mounted control device 222…Second Switching Unit 301…In-vehicle system 320…Vehicle-mounted control device 322…Second switching section.

Claims

1. A vehicle-mounted control device, comprising a vehicle-mounted system, the vehicle-mounted system including a first power supply unit, a load, a first power path disposed between the first power supply unit and the load, a second power supply unit, and a second power path disposed between the second power supply unit and the first power path. The vehicle-mounted control device has the following features: The first switching unit is located in the first power path at a position closer to the first power source than the connection portion of the second power path. A second switching unit is located in the second power path; and The control unit controls the first switching unit and the second switching unit. The first switching unit switches between a first permitted state that allows current to flow from the first power supply side to the load side and a first interrupted state that cuts off current flow from the load side to the first power supply side. The second switching unit switches between a second permitted state, which allows current to flow from the second power source side to the first power path side, and a second interrupted state, which interrupts current flow from the second power source side to the first power path side. When the start condition is met, the control unit performs a first control, setting the first switching unit to the first permitted state and the second switching unit to the second cut-off state. When the voltage of the first power path falls below a threshold voltage while the first control is in effect, the control unit performs a second control that sets the first switching unit to the first disconnect state and the second switching unit to the second allow state. When the second control is performed, the control unit performs at least one of cut-off control and current limiting control; the cut-off control is as follows: when the current flowing through the second power path exceeds the cut-off threshold, the second switching unit is switched to the second cut-off state; the current limiting control is as follows: when the current flowing through the second power path exceeds the limiting threshold, the second switching unit is controlled to suppress the current flowing through the second power path to below the limiting threshold.

2. The vehicle-mounted control device according to claim 1, wherein, The second switching unit includes a switching unit and a voltage conversion unit arranged in parallel with the switching unit. The switching unit switches between a conducting state, which allows current to flow from the second power source side to the first power path side via itself, and a disconnecting state, which prevents current from flowing from the second power source side to the first power path side via itself. The voltage conversion unit performs a voltage conversion operation, boosting or bucking the voltage input from the second power supply side and outputting it to the first power path side. When the voltage of the first power path is below the threshold voltage under the first control state, the control unit performs the second control, which controls the first switching unit to the first cut-off state, controls the switching unit to the on state, and causes the voltage conversion unit to perform the voltage conversion operation; when the current flowing through the second power path exceeds the limit threshold under the second control state, the control unit causes the voltage conversion unit to perform the voltage conversion operation to suppress the current flowing through the second power path to be below the limit threshold.

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

4. The vehicle-mounted control device according to claim 1, wherein, The second switching unit includes a switch section. By turning the switch section to an ON state, the second switching unit enters a second ON state; by turning the switch section to an OFF state, the second switching unit enters a second OFF state. When the current flowing through the second power path exceeds the cutoff threshold while the second control is in effect, the control unit performs the cutoff control to switch the switch unit to the off state.

5. The vehicle-mounted control device according to claim 1, wherein, The second switching unit includes a voltage conversion unit that performs a voltage conversion operation on the voltage input from the second power supply side, either boosting or bucking it before outputting it to the first power path side. When the voltage conversion operation is performed by the voltage conversion unit, the second switching unit enters a second enabled state; when the voltage conversion operation is stopped by the voltage conversion unit, the second switching unit enters a second disabled state. When the current flowing through the second power path exceeds the limit threshold while the second control is in effect, the control unit causes the voltage conversion unit to perform the voltage conversion operation to suppress the current flowing through the second power path to below the limit threshold.

6. The vehicle-mounted control device according to any one of claims 1 to 5, wherein, The vehicle-mounted control device includes an overcurrent prevention unit located in the first power path. The overcurrent prevention unit prevents overcurrent from flowing through the first power path.

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