Vehicle-mounted control device

Abstract

A vehicle-mounted control device (30) comprises control units (for example, a first control unit (51) and a second control unit (52)). When the start switch of a vehicle is in an off state, if the remaining amount of a first battery (for example, a low-voltage battery (2)) is greater than a threshold, the control units control a first switch unit (41) and a second switch unit (42) to be in off states, and, if the remaining amount of the first battery becomes less than or equal to the threshold, the control units switch the second switch unit (42) to be in an on state while maintaining the first switch unit (41) in the off state.

Description

Vehicle-mounted control device

[0001] The present disclosure relates to a vehicle-mounted control device.

[0002] Patent Document 1 discloses a power supply system applied to a power supply monitoring device. This power supply system includes a first system having a first power supply and a second power supply having a second power supply. The first system and the second system can be connected to each other by an inter-system switch. The first power supply has a converter that generates an operating voltage for an electrical load. The second power supply has a storage battery that can be charged by the converter. The power supply monitoring device includes a charge control unit and a dark current supply unit. The charge control unit closes the inter-system switch and causes the voltage generation unit to charge the storage battery under the system operating state. The dark current supply unit closes the inter-system switch and causes the storage battery to supply dark current to the electrical load under the system stop state.

[0003] Under the system stop state, voltage generation by the converter has stopped. When the SOC of the storage battery drops to the capacity threshold, the converter starts up and the storage battery is charged by the converter. When the SOC of the storage battery rises to the upper limit value, the converter stops and charging of the storage battery is stopped.

[0004] Japanese Unexamined Patent Application Publication No. 2023-90443

[0005] In the configuration of Patent Document 1, there is a problem that under the system stop state, the charge and discharge of the storage battery are repeated, and the power loss associated with the charge and discharge tends to increase.

[0006] An object of the present disclosure is to provide a technology capable of continuing the supply of dark current to a load while suppressing the power loss associated with charge and discharge even after the storage battery becomes insufficient in remaining amount due to the supply of dark current from the storage battery to the load.

[0007] The in-vehicle control device of the present disclosure is an in-vehicle control device included in an in-vehicle system comprising: a first battery; a second battery; a first conductive path provided between the first battery and the second battery; a second conductive path provided between the first conductive path and the second battery; a first load electrically connected to the first conductive path; and a second load electrically connected to the second conductive path, wherein the control device comprises: a first switch unit provided between the first battery and the first conductive path; a second switch unit provided between the first conductive path and the second conductive path; and a control unit that controls the first switch unit and the second switch unit, wherein the first switch unit switches between an ON state that allows current to flow from the first conductive path to the first battery and an OFF state that prevents current from flowing from the first conductive path to the first battery, and when in the OFF state, it allows current to flow from the first battery to the first conductive path. The second switch unit switches between an ON state, which allows current to flow from the second conductive path to the first conductive path, and an OFF state, which prevents current from flowing from the second conductive path to the first conductive path. The control unit, when the vehicle's start switch is OFF and the remaining charge of the first battery exceeds a threshold, controls the first switch unit and the second switch unit to the OFF state. When the remaining charge of the first battery falls below the threshold, the control unit switches the second switch unit to the ON state while keeping the first switch unit in the OFF state.

[0008] According to the technology disclosed herein, even after the battery becomes depleted, the supply of dark current from the battery to the load can be continued while suppressing power loss associated with charging and discharging.

[0009] Figure 1 is a schematic diagram showing an in-vehicle system equipped with an in-vehicle control device according to the first embodiment. Figure 2 is a conceptual diagram illustrating the operation of the in-vehicle system when the start switch is ON in the first embodiment. Figure 3 is a conceptual diagram illustrating the operation of the in-vehicle system when the start switch is OFF and the low-voltage battery charge is sufficient in the first embodiment. Figure 4 is a conceptual diagram illustrating the operation of the in-vehicle system when the start switch is OFF and the low-voltage battery charge is low in the first embodiment.

[0010] [Description of Embodiments of the Disclosure] First, embodiments of the Disclosure will be listed and described.

[0011] [1] An in-vehicle control device included in an in-vehicle system comprising: a first battery; a second battery; a first conductive path provided between the first battery and the second battery; a second conductive path provided between the first conductive path and the second battery; a first load electrically connected to the first conductive path; and a second load electrically connected to the second conductive path, comprising: a first switch unit provided between the first battery and the first conductive path; a second switch unit provided between the first conductive path and the second conductive path; and a control unit that controls the first switch unit and the second switch unit, wherein the first switch unit switches between an ON state that allows current to flow from the first conductive path to the first battery and an OFF state that prevents current from flowing from the first conductive path to the first battery, and when in the OFF state, it allows current to flow from the first battery to the first conductive path. The second switch unit switches between an ON state that allows current to flow from the second conductive path to the first conductive path and an OFF state that prevents current from flowing from the second conductive path to the first conductive path. The control unit controls the first switch unit and the second switch unit to the OFF state when the vehicle's start switch is OFF and the remaining charge of the first battery exceeds a threshold, and switches the second switch unit to the ON state while keeping the first switch unit OFF when the remaining charge of the first battery falls below the threshold.

[0012] The control unit of the above-mentioned in-vehicle control device controls the first and second switch units to the OFF state when the vehicle's start switch is OFF and the remaining charge of the first battery exceeds a threshold. This allows the first battery to supply quiescent current to the first load, the second battery to supply quiescent current to the second load, and the second switch unit to interrupt the current supply from the second battery to the first conductive path. When the remaining charge of the first battery falls below the threshold, the control unit switches the second switch unit to the ON state while keeping the first switch unit in the OFF state. This allows the second battery to supply quiescent current to the first load without charging the first battery. In other words, with this configuration, the supply of quiescent current to the first load can be continued without repeatedly charging and discharging the first battery, thus suppressing power loss associated with charging and discharging while continuing to supply quiescent current to the first load.

[0013] [2] The in-vehicle control device according to [1], comprising a first ECU having the first switch section and a second ECU having the second switch section.

[0014] This configuration makes it possible to achieve a system that continuously supplies dark current to the first load while suppressing power loss associated with charging and discharging, by utilizing the first and second switch sections provided in separate ECUs.

[0015] [3] The in-vehicle control device according to [2], comprising a third switch section provided between the first conductive path and the second switch section, wherein the third switch section switches between an ON state that allows bidirectional current flow through itself and an OFF state that prevents current from flowing from the first conductive path side to the second conductive path side, and the third switch section is provided in the first ECU.

[0016] With this configuration, when the first switch is in the off state, it is possible to prevent current from flowing from one end of the first conductive path to the outside of the first ECU, and when the third switch is in the off state, it is possible to prevent current from flowing from the other end of the first conductive path to the outside of the first ECU.

[0017] [4] The in-vehicle control device according to [3], wherein the first ECU comprises a first control unit which constitutes a part of the control unit, the second ECU comprises a second control unit which constitutes a part of the control unit, the first control unit switches the third switch unit to the ON state and transmits a notification signal to the second control unit when it determines that the remaining charge of the first battery has fallen below the threshold, and the second control unit switches the second switch unit to the ON state when it receives the notification signal.

[0018] With this configuration, the first ECU can switch the third switch unit to the ON state when it determines that the remaining charge of the first battery has fallen below a threshold, thereby allowing current to flow from the second conductive path to the first conductive path via the third switch unit. Furthermore, the second ECU can switch the second switch unit to the ON state when the remaining charge of the first battery falls below a threshold, without having to determine itself that the remaining charge of the first battery has fallen below a threshold.

[0019] [5] The in-vehicle control device according to any one of [2] to [4], wherein the first ECU and the second ECU are zone ECUs.

[0020] The above-described in-vehicle control device can be applied to vehicles with a zone architecture.

[0021] [6] The in-vehicle control device according to any one of [1] to [5], wherein the first battery is a low-voltage battery, the second battery is a high-voltage battery, and a voltage conversion unit is provided between the second conductive path and the high-voltage battery, and the voltage conversion unit steps down the voltage input from the high-voltage battery and outputs it to the second conductive path when the remaining charge of the low-voltage battery falls below the threshold.

[0022] With this configuration, the low-voltage battery, which is prone to running low on charge, is monitored, and when the remaining charge of the low-voltage battery falls below a threshold, power can be supplied to the first load from the high-voltage battery.

[0023] [Details of Embodiments of the Disclosure] 1. First Embodiment 1-1. Diagram 1 of the configuration of the in-vehicle system 1 shows an in-vehicle system 1 equipped with an in-vehicle control device 30 of the first embodiment. The in-vehicle system 1 is a system mounted on a vehicle. The in-vehicle system 1 comprises a low-voltage battery 2, a detection unit 3, a high-voltage battery 4, a voltage conversion unit 5, a voltage control unit 6, a communication line 7, a first conductive path 11, a second conductive path 12, a third conductive path 13, a fourth conductive path 14, a fifth conductive path 15, a first load 21, a second load 22, a third load 23, and an in-vehicle control device 30.

[0024] The low-voltage battery 2 is a battery with a lower output voltage than the high-voltage battery 4. The low-voltage battery 2 is composed of, for example, a lithium-ion battery or a lead-acid battery. The detection unit 3 detects the remaining charge of the low-voltage battery 2, or information necessary for measuring the remaining charge of the low-voltage battery 2. The remaining charge of the low-voltage battery 2 may be, for example, the State of Charge (SOC) of the low-voltage battery 2, or the voltage of the low-voltage battery 2. Information necessary for measuring the remaining charge of the low-voltage battery 2 may be, for example, the voltage of the low-voltage battery 2 or the current flowing through the low-voltage battery 2. The detection unit 3 may be configured as part of a battery module including the low-voltage battery 2, or it may be provided separately from the battery module.

[0025] The high-voltage battery 4 is a battery with a higher output voltage than the low-voltage battery 2. The high-voltage battery 4 is composed of, for example, a lithium-ion battery.

[0026] The first conductive path 11 is provided between the low-voltage battery 2 and the high-voltage battery 4. The second conductive path 12 is provided between the first conductive path 11 and the high-voltage battery 4. The third conductive path 13 is provided between the second conductive path 12 and the high-voltage battery 4. The fourth conductive path 14 is provided between the third conductive path 13 and the high-voltage battery 4. The fifth conductive path 15 is provided between the low-voltage battery 2 and the first conductive path 11.

[0027] The voltage conversion unit 5 is provided between the fourth conductive path 14 and the high-voltage battery 4. The voltage conversion unit 5 performs a conversion operation in which it steps down the voltage input from the high-voltage battery 4 and outputs it to the fourth conductive path 14.

[0028] The voltage control unit 6 is configured to include, for example, a microcomputer. The voltage control unit 6 includes, for example, a processor such as a CPU, memory such as ROM or RAM, and a communication interface. The voltage control unit 6 controls the voltage conversion unit 5. The first control unit 51 can communicate via a communication line 7 or the like.

[0029] The first load 21 is electrically connected to the first conductive path 11. In the example shown in Figure 1, the first load 21 is connected to the first conductive path 11 without a switch, but it may be connected to the first conductive path 11 via a switch. Multiple first loads 21 connected to the first conductive path 11 may be provided.

[0030] The second load 22 is electrically connected to the second conductive path 12. In the example shown in Figure 1, the second load 22 is connected to the second conductive path 12 without a switch, but it may be connected to the second conductive path 12 via a switch. Multiple second loads 22 connected to the second conductive path 12 may be provided.

[0031] The third load 23 is electrically connected to the third conductive path 13. In the example shown in Figure 1, the third load 23 is connected to the third conductive path 13 without a switch, but it may also be connected to the third conductive path 13 via a switch. Multiple third loads 23 connected to the third conductive path 13 may be provided.

[0032] 1-2. Configuration of the On-board Control Device 30 The on-board control device 30 comprises a first ECU 31, a second ECU 32, and a third ECU 33. The first ECU 31, the second ECU 32, and the third ECU 33 are Electronic Control Units.

[0033] In this embodiment, the first ECU 31, the second ECU 32, and the third ECU 33 are zone ECUs. A zone ECU is an ECU that is located in each of a plurality of zones within a vehicle and controls the equipment provided in the corresponding zone. The first ECU 31 is located, for example, in the zone on the front and left side of the vehicle with respect to the direction of travel. The second ECU 32 is located, for example, in the zone on the front and right side of the vehicle with respect to the direction of travel. The third ECU 33 is located, for example, in the zone on the rear side of the vehicle with respect to the direction of travel.

[0034] The first ECU 31 comprises a first circuit board 34, a first switch unit 41, a third switch unit 43, and a first control unit 51. The first conductive path 11, the first switch unit 41, the third switch unit 43, and the first control unit 51 are installed on the first circuit board 34.

[0035] The first switch unit 41 is provided between the low-voltage battery 2 and the first conductive path 11. One end of the first switch unit 41 is electrically connected to one end of the fifth conductive path 15, and the other end of the first switch unit 41 is electrically connected to one end of the first conductive path 11. The first switch unit 41 switches between an ON state, which allows current to flow from the first conductive path 11 to the low-voltage battery 2 through it, and an OFF state, which prevents current from flowing from the first conductive path 11 to the low-voltage battery 2 through it. When the first switch unit 41 is in the OFF state, it allows current to flow from the low-voltage battery 2 to the first conductive path 11 through it. When the first switch unit 41 is in the ON state, it allows current to flow from the low-voltage battery 2 to the first conductive path 11 through it. In this embodiment, the first switch unit 41 is composed of a Field Effect Transistor (FET), more specifically, an N-channel MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). When the first switch unit 41 is in the off state, it allows current to flow from the low-voltage battery 2 side to the first conductive path 11 side via its body diode 41A. The first switch unit 41 is a normally-off type, turning on when a high-level signal is applied to its input (specifically, its gate), and turning off when a low-level signal is applied to its input (specifically, its gate).

[0036] The third switch unit 43 is provided between the first conductive path 11 and the second conductive path 12. One end of the third switch unit 43 is electrically connected to the other end of the first conductive path 11. The third switch unit 43 switches between an ON state, which allows current to flow from the first conductive path 11 to the second conductive path 12 through it, and an OFF state, which prevents current from flowing from the first conductive path 11 to the second conductive path 12 through it. When the third switch unit 43 is in the OFF state, it allows current to flow from the second conductive path 12 to the first conductive path 11 through it. When the third switch unit 43 is in the ON state, it allows current to flow from the second conductive path 12 to the first conductive path 11 through it. In this embodiment, the third switch unit 43 is composed of a Field Effect Transistor (FET), more specifically, an N-channel MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). When the third switch unit 43 is in the off state, it allows current to flow from the second conductive path 12 to the first conductive path 11 through itself via its body diode 43A. The third switch unit 43 is normally off, turning on when a high-level signal is applied to its input (specifically, its gate), and turning off when a low-level signal is applied to its input (specifically, its gate).

[0037] The first control unit 51 is configured to include, for example, a microcomputer. The first control unit 51 includes, for example, a processor such as a CPU, memory such as ROM or RAM, a communication interface, etc. The first control unit 51 controls the first switch unit 41 and the third switch unit 43. The first control unit 51 is capable of communication via a communication line 7 or the like.

[0038] The second ECU 32 comprises a second circuit board 35, a second switch unit 42, a fourth switch unit 44, and a second control unit 52. The second conductive path 12, the second switch unit 42, the fourth switch unit 44, and the second control unit 52 are installed on the second circuit board 35.

[0039] The second switch unit 42 is provided between the first conductive path 11 and the second conductive path 12. One end of the second switch unit 42 is electrically connected to the other end of the third switch unit 43, and the other end of the second switch unit 42 is electrically connected to one end of the second conductive path 12. The second switch unit 42 switches between an ON state, which allows current to flow from the second conductive path 12 to the first conductive path 11 through it, and an OFF state, which prevents current from flowing from the second conductive path 12 to the first conductive path 11 through it. When the second switch unit 42 is in the OFF state, it allows current to flow from the first conductive path 11 to the second conductive path 12 through it. When the second switch unit 42 is in the ON state, it allows current to flow from the first conductive path 11 to the second conductive path 12 through it. In this embodiment, the second switch unit 42 is composed of a Field Effect Transistor (FET), more specifically, an N-channel MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). When the second switch unit 42 is in the off state, it allows current to flow from the first conduction path 11 to the second conduction path 12 through its body diode 42A. The second switch unit 42 is normally off, turning on when a high-level signal is applied to its input (specifically, its gate), and turning off when a low-level signal is applied to its input (specifically, its gate).

[0040] The fourth switch unit 44 is provided between the second conductive path 12 and the third conductive path 13. One end of the fourth switch unit 44 is electrically connected to the other end of the second conductive path 12, and the other end of the fourth switch unit 44 is electrically connected to one end of the third conductive path 13. The fourth switch unit 44 switches between an ON state, which allows current to flow from the second conductive path 12 to the third conductive path 13 through it, and an OFF state, which prevents current from flowing from the second conductive path 12 to the third conductive path 13 through it. When the fourth switch unit 44 is in the OFF state, it allows current to flow from the third conductive path 13 to the second conductive path 12 through it. When the fourth switch unit 44 is in the ON state, it allows current to flow from the third conductive path 13 to the second conductive path 12 through it. In this embodiment, the fourth switch unit 44 is composed of a Field Effect Transistor (FET), more specifically, an N-channel MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). When the fourth switch unit 44 is in the off state, it allows current to flow from the third conduction path 13 to the second conduction path 12 through itself via its body diode 44A. The fourth switch unit 44 is normally off, turning on when a high-level signal is applied to its input (specifically, its gate), and turning off when a low-level signal is applied to its input (specifically, its gate).

[0041] The second control unit 52 is configured to include, for example, a microcomputer. The second control unit 52 includes, for example, a processor such as a CPU, memory such as ROM or RAM, a communication interface, etc. The second control unit 52 controls the second switch unit 42 and the fourth switch unit 44. The second control unit 52 can communicate via a communication line 7 or the like.

[0042] The third ECU 33 comprises a third circuit board 36, a fifth switch unit 45, and a third control unit 53. The third conductive path 13, the fifth switch unit 45, and the third control unit 53 are installed on the third circuit board 36.

[0043] The fifth switch unit 45 is provided between the third conductive path 13 and the fourth conductive path 14. One end of the fifth switch unit 45 is electrically connected to the other end of the third conductive path 13, and the other end of the fifth switch unit 45 is electrically connected to one end of the fourth conductive path 14. The fifth switch unit 45 switches between an on state that allows current to flow from the third conductive path 13 side to the fourth conductive path 14 side through itself and an off state that prevents current from flowing from the third conductive path 13 side to the fourth conductive path 14 side through itself. When in the off state, the fifth switch unit 45 allows current to flow from the fourth conductive path 14 side to the third conductive path 13 side through itself. When in the on state, the fifth switch unit 45 allows current to flow from the fourth conductive path 14 side to the third conductive path 13 side through itself. In the present embodiment, the fifth switch unit 45 is constituted by a FET (Field Effect Transistor), and more specifically, is constituted by an N-channel type MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). When in the off state, the fifth switch unit 45 allows current to flow from the fourth conductive path 14 side to the third conductive path 13 side through its body diode 45A.

[0044] The third control unit 53 is configured to include, for example, a microcomputer. The third control unit 53 includes, for example, a processor such as a CPU, a memory such as a ROM and a RAM, a communication interface, and the like. The third control unit 53 controls the fifth switch unit 45. The third control unit 53 can communicate via a communication line 7 or the like. The first control unit 51, the second control unit 52, and the third control unit 53 correspond to an example of a control unit.

[0045] 1-3. Operation of the On-board Control Device 30 When the vehicle's start switch is ON, the first control unit 51 controls the first switch unit 41 and the third switch unit 43 to the ON state, the second control unit 52 controls the second switch unit 42 and the fourth switch unit 44 to the ON state, the third control unit 53 controls the fifth switch unit 45 to the ON state, and the voltage control unit 6 causes the voltage conversion unit 5 to perform a conversion operation. As a result, as shown in Figure 2, the power supplied from the high-voltage battery 4 is converted to voltage by the voltage conversion unit 5 and supplied to the first load 21, the second load 22, the third load 23, and the low-voltage battery 2. The start switch is, for example, an ignition switch or a power switch. The first control unit 51, the second control unit 52, and the third control unit 53 receive a signal indicating the ON / OFF state of the start switch, for example via a communication line 7, and determine the ON / OFF state of the vehicle's start switch based on that signal.

[0046] When the vehicle's start switch is turned off, the first control unit 51 turns off the first switch unit 41 and the third switch unit 43, the second control unit 52 turns off the second switch unit 42 and the fourth switch unit 44, and the third control unit 53 turns off the fifth switch unit 45. The voltage control unit 6 causes the voltage conversion unit 5 to continue the conversion operation. As a result, as shown in Figure 3, the flow of current is interrupted between the first conductive path 11 and the second conductive path 12. Dark current is then supplied from the low-voltage battery 2 to the first load 21 via the body diode 41A of the first switch unit 41. Dark current from the high-voltage battery 4 is converted to voltage by the voltage conversion unit 5 and supplied to the third load 23 via the body diode 45A of the fifth switch unit 45, and supplied to the second load 22 via the body diode 44A of the fourth switch unit 44 and the body diode 45A of the fifth switch unit 45.

[0047] As the state shown in Figure 3 continues, the remaining charge of the low-voltage battery 2 decreases. The first control unit 51 monitors the remaining charge of the low-voltage battery 2 when the start switch is off. Based on the detection result output from the detection unit 3, the first control unit 51 determines the remaining charge of the low-voltage battery 2.

[0048] The first control unit 51 repeatedly determines whether or not the remaining amount of the low-voltage battery 2 has become less than or equal to the threshold value. The remaining amount of the low-voltage battery 2 becoming less than or equal to the threshold value means that the remaining amount of the low-voltage battery 2 is insufficient. When the first control unit 51 determines that the remaining amount of the low-voltage battery 2 exceeds the threshold value, the first switch unit 41 and the third switch unit 43 are maintained in the off state.

[0049] When the first control unit 51 determines that the remaining amount of the low-voltage battery 2 has become less than or equal to the threshold value, as shown in FIG. 4, while maintaining the first switch unit 41 in the off state, an on signal is given to the third switch unit 43 to switch the third switch unit 43 to the on state. Then, the first control unit 51 transmits a notification signal to the second control unit 52 via the communication line 7. The notification signal is a signal for notifying that the remaining amount of the low-voltage battery 2 has become less than or equal to the threshold value. When receiving the notification signal, the second control unit 52 gives an on signal to the second switch unit 42 while maintaining the fourth switch unit 44 in the off state to switch the second switch unit 42 to the on state. Thereby, while cutting off the power supply to the low-voltage battery 2, the power from the high-voltage battery 4 can be voltage-converted by the voltage conversion unit 5 and supplied to the first load 21, the second load 22, and the third load 23.

[0050] Note that when the remaining amount of the low-voltage battery 2 becomes less than or equal to the threshold value, the first control unit 51 may maintain the third switch unit 43 in the off state, the second control unit 52 may switch the fourth switch unit 44 to the on state, and the third control unit 53 may switch the fifth switch unit 45 to the on state.

[0051] 1-4. Effects of the First Embodiment When the start switch is off, the in-vehicle control device 30 controls the first switch unit 41 and the second switch unit 42 to the off state when the remaining charge of the low-voltage battery 2 exceeds a threshold. This allows the low-voltage battery 2 to supply dark current to the first load 21, the high-voltage battery 4 to supply dark current to the second load 22, and the second switch unit 42 to interrupt the current supply from the high-voltage battery 4 to the first conductive path 11. When the remaining charge of the low-voltage battery 2 falls below the threshold, the in-vehicle control device 30 switches the second switch unit 42 to the on state while keeping the first switch unit 41 in the off state. This allows dark current to be supplied from the high-voltage battery 4 to the first load 21 without charging the low-voltage battery 2. In other words, the in-vehicle control device 30 allows the supply of dark current to the first load 21 to be continued without repeatedly charging and discharging the low-voltage battery 2, thus allowing the supply of dark current to the first load 21 to be continued while suppressing power loss associated with charging and discharging.

[0052] According to the in-vehicle control device 30, by utilizing the first switch unit 41 and the second switch unit 42 provided in separate ECUs, it is possible to realize a configuration that continues to supply dark current to the first load 21 while suppressing power loss associated with charging and discharging.

[0053] According to the in-vehicle control device 30, when the first switch unit 41 is in the off state, it is possible to prevent current from flowing from one end of the first conductive path 11 to the outside of the first ECU 31, and when the third switch unit 43 is in the off state, it is possible to prevent current from flowing from the other end of the first conductive path 11 to the outside of the first ECU 31.

[0054] According to the in-vehicle control device 30, the first ECU 31 can switch the third switch unit 43 to the ON state when it determines that the remaining charge of the low-voltage battery 2 has fallen below a threshold, thereby allowing current to flow from the second conductive path 12 to the first conductive path 11 via the third switch unit 43. Furthermore, the second ECU 32 can switch the second switch unit 42 to the ON state when the remaining charge of the low-voltage battery 2 falls below a threshold, without having to determine itself that the remaining charge of the low-voltage battery 2 has fallen below a threshold.

[0055] The in-vehicle control device 30 can be applied to vehicles with a zone architecture.

[0056] According to the in-vehicle control device 30, the low-voltage battery 2, which is prone to running out of charge, is monitored, and when the remaining charge of the low-voltage battery 2 falls below a threshold, power can be supplied from the high-voltage battery 4 to the first load 21.

[0057] <Other Embodiments> This disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of the features of the embodiments described above or below is possible as long as it does not contradict the original. Furthermore, any feature of the embodiments described above or below may be omitted unless explicitly stated as essential. In addition, the embodiments described above may be modified as follows.

[0058] In the first embodiment described above, the first battery was a low-voltage battery and the second battery was a high-voltage battery, but the configuration is not limited to this. For example, the output voltage of the first battery and the output voltage of the second battery may be the same.

[0059] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is indicated by the claims, and all modifications within the meaning and scope of the claims are intended to be included.

[0060] 1...In-vehicle system 2...Low-voltage battery (first battery) 3...Detection unit 4...High-voltage battery (second battery) 5...Voltage conversion unit 6...Voltage control unit 7...Communication line 11...First conductive path 12...Second conductive path 13...Third conductive path 14...Fourth conductive path 15...Fifth conductive path 21...First load 22...Second load 23...Third load 30...In-vehicle control device 31...First ECU 32...Second ECU 33...Third ECU 34...First circuit board 35...Second circuit board 36...Third circuit board 41...First switch unit 41A...Body diode 42...Second switch unit 42A...Body diode 43...Third switch unit 43A...Body diode 44...Fourth switch unit 44A...Body diode 45...Fifth switch unit 45A...Body diode 51...First control unit (control unit) 52...Second control unit (control unit) 53...Third control unit (control unit)

Claims

1. An in-vehicle control device included in an in-vehicle system comprising: a first battery; a second battery; a first conductive path provided between the first battery and the second battery; a second conductive path provided between the first conductive path and the second battery; a first load electrically connected to the first conductive path; and a second load electrically connected to the second conductive path, comprising: a first switch unit provided between the first battery and the first conductive path; a second switch unit provided between the first conductive path and the second conductive path; and a control unit that controls the first switch unit and the second switch unit, wherein the first switch unit switches between an ON state that allows current to flow from the first conductive path to the first battery and an OFF state that prevents current from flowing from the first conductive path to the first battery, and when in the OFF state, allows current to flow from the first battery to the first conductive path. The second switch unit switches between an ON state that allows current to flow from the second conductive path to the first conductive path and an OFF state that prevents current from flowing from the second conductive path to the first conductive path. The control unit controls the first switch unit and the second switch unit to the OFF state when the vehicle's start switch is OFF and the remaining charge of the first battery exceeds a threshold, and switches the second switch unit to the ON state while keeping the first switch unit OFF when the remaining charge of the first battery falls below the threshold.

2. The in-vehicle control device according to claim 1, comprising a first ECU having the first switch section and a second ECU having the second switch section.

3. The in-vehicle control device according to claim 2, further comprising a third switch section provided between the first conductive path and the second switch section, wherein the third switch section switches between an ON state that allows bidirectional current flow through itself and an OFF state that prevents current from flowing from the first conductive path to the second conductive path, and the third switch section is provided in the first ECU.

4. The in-vehicle control device according to claim 3, wherein the first ECU comprises a first control unit which constitutes a part of the control unit, the second ECU comprises a second control unit which constitutes a part of the control unit, the first control unit switches the third switch unit to the ON state and transmits a notification signal to the second control unit when it determines that the remaining charge of the first battery has fallen below the threshold, and the second control unit switches the second switch unit to the ON state when it receives the notification signal.

5. The in-vehicle control device according to any one of claims 2 to 4, wherein the first ECU and the second ECU are zone ECUs.

6. The in-vehicle control device according to any one of claims 1 to 4, wherein the first battery is a low-voltage battery, the second battery is a high-voltage battery, and a voltage conversion unit is provided between the second conductive path and the high-voltage battery, and the voltage conversion unit steps down the voltage input from the high-voltage battery and outputs it to the second conductive path when the remaining charge of the low-voltage battery falls below the threshold.

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