In-vehicle device, control method, and program

Abstract

To provide an on-vehicle device, etc., capable of efficiently performing power supply using a machine type relay and a semiconductor switch in a configuration comprising the machine type relay and the semiconductor switch.SOLUTION: An on-vehicle device is mounted on a vehicle and controls power supply to one or more loads. A state of the vehicle includes a normal current state where current consumption of the loads is a normal current and a low current state where the current consumption of the loads is small. The on-vehicle device comprises: a machine type relay which is connected between a battery power source of the vehicle and the loads; a first semiconductor relay which is connected in parallel with the machine type relay; a first control circuit which turns on the machine type relay in a case where the vehicle is in the normal current state, and turns off the machine type relay in a case where the vehicle is in the low current state; and a second control circuit which turns off the first semiconductor relay in the case where the vehicle is in the normal current state, and turns on the first semiconductor relay in the case where the vehicle is in the low current state.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an in-vehicle device, a control method, and a program.

Background Art

[0002] A vehicle is equipped with a power supply control device (see, for example, Patent Document 1) that controls power supply from a battery to a load. In the power supply control device described in Patent Document 1, a semiconductor switch is provided in the current path of the current flowing from the battery to the load, and the power supply from the battery to the load is controlled by switching the semiconductor switch on or off.

[0003] The semiconductor switch has a control terminal. For example, when the semiconductor switch is a FET (Field Effect Transistor), the control terminal is the gate. The resistance value between both ends of the semiconductor switch changes according to the voltage of the control terminal. By adjusting the voltage of the control terminal, the resistance value between both ends of the semiconductor switch is adjusted to a sufficiently small value, and the semiconductor switch is switched on. By adjusting the voltage of the control terminal, the resistance value between both ends of the semiconductor switch is adjusted to a sufficiently large value, and the semiconductor switch is switched off.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the power supply control device of Document 1, in a configuration including a mechanical relay and a semiconductor relay, the aspect of power supply using these mechanical relay and semiconductor relay is not considered.

[0006] This disclosure aims to provide an in-vehicle device, etc., that can efficiently supply power using mechanical relays and semiconductor switches in a configuration comprising these mechanical relays and semiconductor switches. [Means for solving the problem]

[0007] An in-vehicle device according to one embodiment of the present disclosure is an in-vehicle device mounted on a vehicle that controls the supply of power to one or more loads, wherein the state of the vehicle includes a normal current state in which the current consumption of the load is normal current and a low current state in which the current consumption of the load is less than normal current, and comprises a mechanical relay connected between the vehicle's battery power supply and the load, a first semiconductor relay connected in parallel with the mechanical relay, a first control circuit that turns on the mechanical relay when the vehicle is in the normal current state and turns off the mechanical relay when the vehicle is in the low current state, and a second control circuit that turns off the first semiconductor relay when the vehicle is in the normal current state and turns on the first semiconductor relay when the vehicle is in the low current state.

[0008] A control method according to one embodiment of the present disclosure is a control method for an on-board device mounted on a vehicle that controls the supply of power to a load, wherein the on-board device comprises a mechanical relay connected between a battery power source and a load, and a first semiconductor relay connected in parallel with the mechanical relay, wherein the control method turns on the mechanical relay when the vehicle is in a normal current state, turns off the mechanical relay when the vehicle is in a low current state, turns off the first semiconductor relay when the vehicle is in a normal current state, and turns on the first semiconductor relay when the vehicle is in a low current state.

[0009] A program according to one embodiment of the present disclosure is a program that causes a computer to execute a process to control an on-board device mounted in a vehicle that controls the supply of power to a load, wherein the on-board device comprises a mechanical relay connected between a battery power source and a load, and a first semiconductor relay connected in parallel with the mechanical relay, and the program causes the computer to execute a process to turn on the mechanical relay when the vehicle is in a normal current state, turn off the mechanical relay when the vehicle is in a low current state, turn off the first semiconductor relay when the vehicle is in a normal current state, and turn on the first semiconductor relay when the vehicle is in a low current state. [Effects of the Invention]

[0010] In an in-vehicle device according to one embodiment of this disclosure, it is possible to efficiently supply power using mechanical relays and semiconductor switches. [Brief explanation of the drawing]

[0011] [Figure 1] This is a block diagram showing the main components of the power supply system in Embodiment 1. [Figure 2] This is a block diagram showing the main components of the microcontroller in Embodiment 1. [Figure 3] This flowchart shows the control processing procedure by the second control circuit in Embodiment 1. [Figure 4] This is a flowchart showing the control processing procedure by the microcontroller in Embodiment 1. [Figure 5] This is a block diagram showing the main components of the power supply system in Embodiment 2. [Figure 6] This is a block diagram showing the main components of the microcontroller in Embodiment 2. [Figure 7] This flowchart shows the control processing procedure by the second control circuit in Embodiment 2. [Figure 8] This is a flowchart showing the control processing procedure by the microcontroller in Embodiment 2. [Figure 9]It is a block diagram showing the main configuration of the power supply system in Embodiment 3. [Figure 10] It is a block diagram showing the main configuration of the microcomputer in Embodiment 3. [Figure 11] It is a flowchart showing the control processing procedure by the microcomputer in Embodiment 3. [Figure 12] It is a block diagram showing the main configuration of the power supply system in Embodiment 4. [Figure 13] It is a block diagram showing the main configuration of the power supply system in Embodiment 5.

Modes for Carrying Out the Invention

[0012] [Description of Embodiments of the Present Invention] First, the embodiments of the present invention will be listed and described. At least a part of the embodiments described below may be arbitrarily combined.

[0013] (1) An in-vehicle device according to an aspect of the present disclosure is an in-vehicle device mounted on a vehicle and controlling power supply to one or more loads, wherein the state of the vehicle includes a normal current state in which the consumption current of the load is a normal current and a low current state in which the consumption current of the load is smaller than the normal current, a mechanical relay connected between the battery power supply of the vehicle and the load, a first semiconductor relay connected in parallel with the mechanical relay, a first control circuit that turns on the mechanical relay when the vehicle is in the normal current state and turns off the mechanical relay when the vehicle is in the low current state, and a second control circuit that turns off the first semiconductor relay when the vehicle is in the normal current state and turns on the first semiconductor relay when the vehicle is in the low current state.

[0014] In this embodiment, power supplied from the battery power source is supplied to the load via an on-board device. That is, the on-board device operates as a power supply control device. When the vehicle is running, normal current flows from the battery power source to the load, and when the vehicle is stopped, a low current (dark current) flows from the battery power source to the load. The value of the low current is lower than the value of the normal current, for example, 10mA to 100mA. The value of the low current is a low value, for example, about one-hundredth or one-thousandth of the value of the normal current. When the vehicle is stopped, the current supplied to the vehicle's load is reduced to a low current, thereby reducing the consumption of the battery power source. The vehicle starts, for example, when the power switch or ignition switch is on, and stops when it is off. Normal current flows from the battery power source to the load via a mechanical relay provided in the on-board device. The vehicle may also be configured such that normal current flows to the load when there are occupants in the vehicle, and low current flows to the load when there are no occupants in the vehicle. As the number of times a mechanical relay is switched on or off (number of contacts) increases, there is a concern that the mechanical relay will deteriorate. When operating a load in a low-current state where a low current flows, it is possible to reduce the number of times current flows through the mechanical relay by supplying current to the load via the first semiconductor relay instead of the mechanical relay. This reduces the number of contacts of the mechanical relay and makes it possible to supply power to the load efficiently. When the vehicle is in a low-current state, the current value flowing to the load is low, so it is possible to reduce the influence of the on-resistance value of the first semiconductor relay. For this reason, for example, a semiconductor with a relatively low rated current value and low cost (for example, an N-channel type FET (Field Effect Transistor)) can be used for the first semiconductor relay, making it possible to realize the configuration according to this embodiment while reducing product cost. Note that a P-channel type FET, transistor, thyristor, or IPD (Intelligent Power Device) may be used for the first semiconductor relay.

[0015] (2) The in-vehicle device according to one aspect of the present disclosure includes a processing unit capable of determining the state of the vehicle. The processing unit determines the state of the vehicle, acquires a first voltage value at a location downstream of the mechanical relay and the first semiconductor relay in the current path and upstream of the load, and based on the determination result of the state of the vehicle and the first voltage value, determines whether the mechanical relay or the first semiconductor relay has failed. When it is determined that the mechanical relay or the first semiconductor relay has failed, the determination result is output.

[0016] In this aspect, when the current value flowing through the load is equal to or greater than a predetermined threshold value (state threshold value), the processing unit determines that the vehicle is in a normal current state. When it is less than the state threshold value, the processing unit determines that the vehicle is in a low current state. Note that the processing unit may determine the state of the vehicle based on the current value flowing from the battery power source to the in-vehicle device. Also, the state threshold value may be a fixed value, or a value that varies according to the remaining capacity of the battery power source or the operating status of the load. When the vehicle is in a normal current state, the first voltage value between the mechanical relay and the load is acquired. When the acquired first voltage value is less than a predetermined value, it is determined that the mechanical relay has an off failure where it cannot turn on. Also, when the vehicle is in a low current state, the processing unit acquires the first voltage value between the first semiconductor relay and the load. When the acquired first voltage value is less than a predetermined value, it is determined that the first semiconductor relay has an off failure where it cannot turn on. When the processing unit determines that the mechanical relay or the first semiconductor relay has failed, for example, by outputting the determination result to a display device such as a panel of a navigation device in the vehicle or an HMI (Human Machine Interface), it is possible to notify the passenger that a failure has occurred. Note that the external server located outside the vehicle may be notified that a failure has occurred.

[0017] (3) In the in-vehicle device according to one aspect of the present disclosure, when the processing unit determines that the first semiconductor relay has failed, the processing unit causes the mechanical relay to turn on in the first control circuit.

[0018] In this embodiment, if the first semiconductor relay fails to turn off and it becomes impossible to supply current to the load via the first semiconductor relay when the vehicle is in a low-current state, it is possible to continue supplying current to the load by turning on the mechanical relay.

[0019] (4) An in-vehicle device according to one aspect of the present disclosure includes a first semiconductor relay which is an N-channel FET with its drain located upstream of the source in the current path, and a second semiconductor relay which is an N-channel FET connected in series with the first semiconductor relay and with its source located upstream of the drain in the current path, wherein the second control circuit turns off the second semiconductor relay when the vehicle is in a normal current state and turns on the second semiconductor relay when the vehicle is in a low current state.

[0020] In this embodiment, the first semiconductor relay is an N-channel FET, and its drain is located upstream of the source. Therefore, when the first semiconductor relay is off, no current flows from the battery power supply to the load. However, if the only semiconductor relay between the power supply and the load is the first semiconductor relay, the effect of the body diode may cause current to flow from the load to the battery power supply if it is accidentally reversed. The second semiconductor relay is also an N-channel FET like the first semiconductor relay, but its source is located upstream of the drain. Therefore, when the second semiconductor relay is off, the effect of the body diode prevents current from flowing from the load to the power supply. Thus, when both the first and second semiconductor relays are off, no current flows from the battery power supply to the load or from the load to the battery power supply, and there is no need to provide any other mechanism to interrupt the current in the event of a reverse connection. Note that either the first or second semiconductor relay may be provided on the upstream side.

[0021] (5) An in-vehicle device according to one aspect of the present disclosure includes a processing unit capable of determining the state of the vehicle, the processing unit determines the state of the vehicle, obtains a first voltage value at a location in the current path that is downstream of the mechanical relay, the first semiconductor relay, and the second semiconductor relay and upstream of the load, obtains a second voltage value at a location in the current path between the first semiconductor relay and the second semiconductor relay, determines whether the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed based on the determination result of the state of the vehicle, the first voltage value, and the second voltage value, and outputs the determination result if it is determined that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed.

[0022] In this embodiment, when the vehicle is in a normal current state, the processing unit acquires a first voltage between the mechanical relay and the load, and if the acquired first voltage is less than a predetermined value, it determines that the mechanical relay is in an off-state fault and will not turn on. When the vehicle is in a low current state, the processing unit acquires a first voltage between the semiconductor relay downstream of the first or second semiconductor relay and the load. The processing unit also acquires a second voltage value between the first and second semiconductor relays. If both the first and second voltage values ​​are less than a predetermined value, the processing unit determines that the semiconductor relay located upstream is in an off-state fault. If the first voltage value is less than a predetermined value and the second voltage value is equal to or greater than a predetermined value, the processing unit determines that the semiconductor relay located downstream is in an off-state fault. When the processing unit determines that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed, it can notify the passenger of the failure by outputting the determination result.

[0023] (6) In an in-vehicle device according to one aspect of the present disclosure, the processing unit determines that the first semiconductor relay or the second semiconductor relay has failed, and instructs the first control circuit to turn on the mechanical relay.

[0024] In this embodiment, if the first semiconductor relay or the second semiconductor relay fails to turn off and the vehicle is in a low-current state, making it impossible to supply current to the load via the first and second semiconductor relays, it is possible to continue supplying current to the load by turning on the mechanical relay.

[0025] (7) An in-vehicle device according to one aspect of the present disclosure includes a second semiconductor relay connected in parallel with the first semiconductor relay, wherein the second control circuit turns off the second semiconductor relay when the vehicle is in a normal current state and turns on the second semiconductor relay when the vehicle is in a low current state.

[0026] In this embodiment, since the first semiconductor relay and the second semiconductor relay are connected in parallel, even if one of them fails to turn off when the vehicle is in a low-current state, it is possible to continue supplying current from the battery power to the load without turning on the mechanical relay.

[0027] (8) An in-vehicle device according to one aspect of the present disclosure comprises a resistor disposed downstream of the first semiconductor relay in the current path, a fault detection circuit that outputs a resistance voltage value that rises when the voltage value across the ends of the resistor rises, and a processing unit capable of determining the state of the vehicle. The processing unit determines the state of the vehicle, obtains a first voltage value at a location downstream of the mechanical relay, the first semiconductor relay, and the second semiconductor relay in the current path and upstream of the load, and the resistance voltage value output by the fault detection circuit, determines whether the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed based on the determination result of the state of the vehicle, the first voltage value, and the resistance voltage value, and outputs the determination result if it determines that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed.

[0028] In this embodiment, when the vehicle is in a normal current state, the processing unit acquires a first voltage value between the mechanical relay and the load, and determines that the mechanical relay is in an off-fault state if the acquired first voltage value is less than a predetermined value. When the vehicle is in a low current state, the processing unit acquires a first voltage between the semiconductor relay downstream of the first semiconductor relay or the second semiconductor relay and the load. The processing unit also acquires the resistance voltage value output by the fault detection circuit. The resistance voltage value is proportional to the voltage value across the resistor, and the resistance voltage value increases when the voltage value across the resistor increases. A lower threshold and an upper threshold are set as thresholds related to the resistance voltage value. The lower threshold is less than the upper threshold and greater than zero. When the vehicle is in a low current state, if the first voltage value is greater than or equal to a predetermined value and the resistance voltage value is less than the lower threshold, the processing unit determines that the first semiconductor relay is in an off-fault state. When the first voltage value is greater than or equal to a predetermined value and the resistance voltage value is greater than or equal to the upper threshold, the processing unit determines that the second semiconductor relay is in an off-fault state. Furthermore, if the first voltage value obtained when the vehicle is in a low-current state is less than a predetermined value, the processing unit determines that the first semiconductor relay and the second semiconductor relay are in an off state. If the processing unit determines that a mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed, it can notify the passenger of the failure by outputting the determination result.

[0029] (9) In an in-vehicle device according to one aspect of the present disclosure, if the processing unit determines that the first semiconductor relay and the second semiconductor relay have failed, the first control circuit is instructed to turn on the mechanical relay.

[0030] In this embodiment, if the first semiconductor relay and the second semiconductor relay fail to turn off, and the vehicle is in a low-current state, making it impossible to supply current to the load via the first or second semiconductor relay, it is possible to continue supplying current to the load by turning on the mechanical relay.

[0031] (10) An in-vehicle device according to one aspect of the present disclosure comprises a first semiconductor relay which is an N-channel FET with its drain located upstream of the source in the current path, and a second semiconductor relay which is an N-channel FET connected in series with the first semiconductor relay and has its drain located upstream of the source in the current path, wherein the second control circuit turns off the second semiconductor relay when the vehicle is in a normal current state and turns on the second semiconductor relay when the vehicle is in a low current state.

[0032] In this embodiment, both the first and second semiconductor relays are N-channel type FETs with their drains located upstream of the source, and the first and second semiconductor relays are connected in series. When there is only one semiconductor relay, it is not possible to interrupt the current when that relay fails to turn off. By connecting the first and second semiconductor relays in series, it is possible to interrupt the current by turning off the other relay even if one of them fails to turn on.

[0033] (11) An in-vehicle device according to one aspect of the present disclosure includes a processing unit capable of determining the state of the vehicle, the processing unit determines the state of the vehicle, obtains a first voltage value at a location in the current path that is downstream of the mechanical relay, the first semiconductor relay, and the second semiconductor relay and upstream of the load, obtains a second voltage value at a location in the current path between the first semiconductor relay and the second semiconductor relay, determines whether the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed based on the determination result of the state of the vehicle, the first voltage value, and the second voltage value, and outputs the determination result if it is determined that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed.

[0034] In this embodiment, when the vehicle is in a normal current state, the processing unit acquires a first voltage between the mechanical relay and the load, and if the acquired first voltage is less than a predetermined value, it determines that the mechanical relay is in an off state and does not turn on. When the vehicle is in a low current state, the processing unit acquires a first voltage between the semiconductor relay downstream of the first or second semiconductor relay and the load. The processing unit also acquires a second voltage value between the first and second semiconductor relays. If both the first and second voltage values ​​are less than a predetermined value, the processing unit determines that the semiconductor relay located upstream is in an off state. If the first voltage value is less than a predetermined value and the second voltage value is equal to or greater than a predetermined value, the processing unit determines that the downstream semiconductor relay is in an off state. When the processing unit determines that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed, it can notify the passenger of the failure by outputting the determination result.

[0035] (12) In an in-vehicle device according to one aspect of the present disclosure, the processing unit determines that the first semiconductor relay or the second semiconductor relay has failed, and instructs the first control circuit to turn on the mechanical relay.

[0036] In this embodiment, if the first semiconductor relay or the second semiconductor relay fails to turn off and the vehicle is in a low-current state, making it impossible to supply current to the load via the first and second semiconductor relays, it is possible to continue supplying current to the load by turning on the mechanical relay.

[0037] (13) An in-vehicle device according to one aspect of the present disclosure, wherein the first semiconductor relay is a P-channel type FET in which the source is located upstream of the drain in the current path, and the second control circuit turns off the first semiconductor relay by increasing the voltage applied to the gate of the first semiconductor relay when the vehicle is in a normal current state, and turns on the first semiconductor relay by decreasing the voltage applied to the gate of the first semiconductor relay when the vehicle is in a low current state.

[0038] In this embodiment, the first semiconductor relay is a P-channel type FET, and the second control circuit can keep the first semiconductor relay in the off state by applying a voltage to the gate of the first semiconductor relay using current from the battery power supply that is equivalent to the voltage applied to the source of the first semiconductor relay when the vehicle is in a normal current state. Furthermore, when the vehicle is in a low current state, the second control circuit can turn on the first semiconductor by stepping down the voltage applied to the gate of the first semiconductor relay. As a result, the voltage applied to the gate of the first semiconductor relay can be reduced when the vehicle is in a low current state, thereby reducing the power consumption of the battery power supply when the vehicle is stopped.

[0039] (14) An in-vehicle device according to one aspect of the present disclosure includes a processing unit capable of determining the state of the vehicle, the processing unit determines the state of the vehicle, obtains a first voltage value at a location in the current path that is downstream of the mechanical relay and the first semiconductor relay and upstream of the load, determines whether the mechanical relay or the first semiconductor relay has failed based on the determination result of the state of the vehicle and the first voltage value, and outputs the determination result if it is determined that the mechanical relay or the first semiconductor relay has failed.

[0040] In this embodiment, when the vehicle is in a normal current state, the processing unit acquires a first voltage value between the mechanical relay and the load, and if the acquired first voltage value is less than a predetermined value, it determines that the mechanical relay is in an off state and does not turn on. Also, when the vehicle is in a low current state, the processing unit acquires a first voltage value between the first semiconductor relay and the load, and if the acquired first voltage value is less than a predetermined value, it determines that the first semiconductor relay is in an off state and does not turn on. If the processing unit determines that the mechanical relay or the first semiconductor relay has failed, it can notify the passenger of the failure by outputting the determination result.

[0041] (15) In an in-vehicle device according to one aspect of the present disclosure, the processing unit determines that the first semiconductor relay has failed and instructs the first control circuit to turn on the mechanical relay.

[0042] In this embodiment, if the first semiconductor relay fails to turn off and it becomes impossible to supply current to the load via the first semiconductor relay when the vehicle is in a low-current state, it is possible to continue supplying current to the load by turning on the mechanical relay.

[0043] (16) A control method according to one aspect of the present disclosure is a control method for an on-board device mounted on a vehicle and controlling the supply of power to a load, the on-board device comprising a mechanical relay connected between a battery power source and a load, and a first semiconductor relay connected in parallel with the mechanical relay, wherein the mechanical relay is turned on when the vehicle is in a normal current state, the mechanical relay is turned off when the vehicle is in a low current state, the first semiconductor relay is turned off when the vehicle is in a normal current state, and the first semiconductor relay is turned on when the vehicle is in a low current state.

[0044] In this embodiment, power can be supplied efficiently using mechanical relays and semiconductor switches.

[0045] (17) A program according to one aspect of the present disclosure is a program that causes a computer to execute a process to control an on-board device mounted in a vehicle that controls the supply of power to a load, wherein the on-board device comprises a mechanical relay connected between a battery power source and a load, and a first semiconductor relay connected in parallel with the mechanical relay, and the program causes the computer to execute a process to turn on the mechanical relay when the vehicle is in a normal current state, to turn off the mechanical relay when the vehicle is in a low current state, to turn off the first semiconductor relay when the vehicle is in a normal current state, and to turn on the first semiconductor relay when the vehicle is in a low current state.

[0046] In this embodiment, power can be supplied efficiently using mechanical relays and semiconductor switches.

[0047] [Details of the embodiments of this disclosure] Specific examples of power supply control devices according to the embodiments of this disclosure will be described below with reference to the drawings. However, the present invention is not limited to these examples and is intended to include all modifications within the meaning and scope of the claims as indicated by the claims.

[0048] (Embodiment 1) Figure 1 is a block diagram showing the main components of the power supply system 1 in Embodiment 1. In Figure 1, current lines are shown by solid lines, and signal lines are shown by dashed lines. The power supply system 1 is mounted on a vehicle and comprises an on-board device 10, a battery power supply 11, and loads 13. The battery power supply 11 is a power supply that outputs DC current. The on-board device 10 is connected to the positive terminal of the battery power supply 11 and one end of a plurality of loads 13. The on-board device 10 is, for example, an ECU (Electronic Control Unit) that controls the current from the battery power supply 11 to the loads 13. The negative terminal of the battery power supply 11 and the other end of the loads 13 are grounded. In the following description, the battery power supply 11 side of the current path from the battery power supply 11 to the loads 13 is referred to as the upstream of the current, and the loads 13 side is referred to as the downstream of the current.

[0049] When the vehicle is started, the battery power supply 11 supplies power (normal current) to operate the loads. When the vehicle is stopped, the battery power supply 11 supplies power at a low current, which is lower than the normal current. The loads 13 to which low current power is supplied are loads that need to operate even when the vehicle is stopped, such as interior lights or security devices. The microcontroller 4 can determine whether the vehicle is in a normal current state or a low current state based on the current values ​​(load current values) of the power supplied to multiple loads 13. Alternatively, the microcontroller 4 may determine whether the vehicle is in a normal current state or a low current state based on the current values ​​supplied from the battery power supply 11 to the onboard equipment.

[0050] Load 13 is an electrical device. When power is supplied to Load 13, Load 13 operates. When the power supply to Load 13 is stopped, Load 13 stops operating. Note that the number of Load 13 connected to the vehicle-mounted device 10 is not limited to one; multiple Load 13 may be connected to the vehicle-mounted device 10.

[0051] The in-vehicle device 10 includes a mechanical relay 2, a first semiconductor relay 31, a microcomputer (MPC) 4, a first control circuit 51, a second control circuit 52, a first voltage detection unit 61, a reverse current prevention element 7, a fuse-cutting element 8, and a pull-up resistor R. These are mounted on a common circuit board. Note that some of the above components may be mounted outside the in-vehicle device 10.

[0052] Mechanical relay 2 is a contact relay that turns on when, for example, current flows through its built-in coil 21, and the conductor 22, attracted by the resulting magnetic force, connects to the current path. Mechanical relay 2 turns on when current flows from the first control circuit 51 to the coil 21, and turns off when the current stops. When mechanical relay 2 is on, current flows from the battery power supply 11 to the load 13, and when mechanical relay 2 is off, no current flows.

[0053] In this embodiment, the first semiconductor relay 31 is, for example, an N-channel FET. The first semiconductor relay 31 is arranged in parallel with the mechanical relay 2 between the battery power supply 11 and the load 13. The first semiconductor relay 31 is also connected to the current path such that its drain is located upstream of the source. The first semiconductor relay 31 turns on when a voltage is applied to its gate from the second control circuit 52, and turns off when the voltage application to the gate stops. When the first semiconductor relay 31 is on, current flows from the battery power supply 11 to the load 13, and when the first semiconductor relay 31 is off, no current flows.

[0054] The first control circuit 51 switches the mechanical relay 2 on or off by controlling the current supplied to the coil 21 of the mechanical relay 2. The first control circuit 51 is an electronic device such as an FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), or ASSP (Application Specific Standard Product). Alternatively, the first control circuit 51 may be a software processing unit such as a microcomputer or DSP (Digital Signal Processor). When the first control circuit 51 receives a signal (Hi voltage) from the microcontroller 4 indicating an instruction to turn on the mechanical relay 2, it turns on the mechanical relay 2 by supplying power to the coil 21 of the mechanical relay 2. When the first control circuit 51 receives a signal (Low voltage) from the microcontroller 4 indicating an instruction to turn off the mechanical relay 2, or when no signal is received, it turns off the mechanical relay 2 by stopping the current supplied to the coil 21 of the mechanical relay 2.

[0055] The second control circuit 52 switches the first semiconductor relay 31 on or off by applying a voltage to the gate of the first semiconductor relay 31. The second control circuit 52 is an electronic device such as an FPGA, ASIC, or ASSP. The second control circuit 52 may also be a software processing unit such as a microcontroller or DSP. When the second control circuit 52 receives a signal (Low voltage) from the microcontroller 4 indicating an instruction to turn off the first semiconductor relay 31, it does not apply a voltage to the gate of the first semiconductor relay 31 and turns off the first semiconductor relay 31. Conversely, when the second control circuit 52 receives a Hi voltage, it considers that a signal indicating an instruction to turn on the first semiconductor relay 31 has been received from the microcontroller 4, applies a voltage to the gate of the first semiconductor relay 31, and turns on the first semiconductor relay 31.

[0056] The pull-up resistor R is connected to the signal lines from the battery power supply 11 and the microcontroller 4 to the second control circuit 52. When the microcontroller 4 stops operating at low current and stops outputting a signal to the second control circuit 52, the voltage of the power that energizes the pull-up resistor R is applied to the signal line from the microcontroller 4 to the second control circuit 52, and a Hi voltage (Hi-Z voltage) is input to the second control circuit 52. As a result, when the microcontroller 4 stops operating, a voltage equivalent to that applied to the second control circuit 52 when the microcontroller 4 outputs a signal indicating an instruction to turn on the first semiconductor relay 31 is applied. This makes it possible for the second control circuit 52 to control the first semiconductor relay 31 even when the microcontroller 4 is stopped. Alternatively, the second control circuit 52 may be configured integrally with the first semiconductor relay 31 by an IPD (Integrated Power Distribution). In this case, it is possible to reduce the power consumed in low current conditions compared to when it is controlled by the microcontroller 4.

[0057] The first voltage detection unit 61 detects a first voltage value at a location downstream of the mechanical relay 2 and the first semiconductor relay 31 and upstream of the load 13. Specifically, the first voltage detection unit 61 can detect a first voltage value at a location downstream of the mechanical relay 2 and upstream of the load 13 when the mechanical relay 2 is turned on, and a first voltage value at a location downstream of the first semiconductor relay 31 and upstream of the load 13 when the first semiconductor relay 31 is turned on. The first voltage detection unit 61 outputs the detected first voltage value to the microcontroller 4.

[0058] The reverse current prevention element 7 is, for example, a diode. The reverse current prevention element 7 is provided upstream of the mechanical relay 2 and the first semiconductor relay 31. The reverse current prevention element 7 interrupts the current flowing from the load 13 to the battery power supply 11 in the event of an accidental reverse connection.

[0059] The fuse 8 is a fuse or a fusible link, etc. One fuse 8 is provided downstream of the mechanical relay 2 and the first semiconductor relay 31, and upstream of each load 13. If a current exceeding the reference current flows through the fuse 8, the fuse 8 will blow. When a current exceeding the reference current flows, the fuse 8 blows, protecting the mechanical relay 2 and the first semiconductor relay 31.

[0060] Figure 2 is a block diagram showing the main components of the microcontroller 4 in Embodiment 1. The microcontroller 4 includes an input unit 41, a storage unit 42, a control unit 43, a first output unit 441, a first A / D conversion unit 451, an external output unit 46, and a current determination unit 48. These are connected to an internal bus 47.

[0061] The input unit 41 receives the sum of the current values ​​of the power supplied to the multiple loads 13 (load current value). The input unit 41 may also receive the current value supplied from the battery power supply 11 to the on-board device (device current value). When the load current value is input to the input unit 41, the input unit 41 notifies the current determination unit 48 of the input load current value.

[0062] The memory unit 42 is a non-volatile memory. The memory unit 42 stores a computer program P (program product). The control unit 43 has a processing element that executes processing, such as a CPU (Central Processing Unit), and functions as a processing unit. The processing element of the control unit 43 executes the following processes by executing the computer program P: the first control circuit 51 switches the mechanical relay 2 on or off; the second control circuit 52 switches the first semiconductor relay 31 on or off; the mechanical relay 2 or the first semiconductor relay 31 fails; and the mechanical relay 2 or the first semiconductor relay 31 fails.

[0063] The computer program P may also be stored in a storage medium A in a manner readable by the processing elements of the control unit 43. In this case, the computer program P read from the storage medium A by a reading device (not shown) is written to the storage unit 42. The storage medium A is an optical disc, a flexible disc, a magnetic disc, a magneto-optical disc, or a semiconductor memory, etc. Optical discs include CD (Compact Disc)-ROM (Read Only Memory), DVD (Digital Versatile Disc)-ROM, or BD (Blu-ray® Disc), etc. Magnetic discs include, for example, hard disks. Alternatively, the computer program P may be downloaded from a device (not shown) connected to a communication network (not shown), and the downloaded computer program P may be written to the storage unit 42.

[0064] Furthermore, the memory unit 42 stores thresholds (state thresholds) for the current determination unit 48 to determine the state of the vehicle, and predetermined values ​​for determining a failure of the mechanical relay 2 or the first semiconductor relay 31.

[0065] The current determination unit 48 determines the state of the vehicle based on the load current value notified from the input unit 41. The current determination unit 48 reads a state threshold from the storage unit 42 and compares the load current value with the state threshold. If the load current value is equal to or greater than the state threshold, the current determination unit 48 determines that the vehicle is in a normal current state. If the load current value is less than the state threshold, the current determination unit 48 determines that the vehicle is in a low current state. The current determination unit 48 outputs the determined state of the vehicle to the control unit 43. The current determination unit 48 may also determine the state of the vehicle based on the current value (device current value) supplied to the on-board device from the battery power supply 11. The current determination unit 48 may perform the above processing using a processing element such as a CPU and be configured as a functional unit of the control unit 43. The current determination unit 48 may also perform the above processing using an analog element such as a comparator.

[0066] The first output unit 441 outputs a signal to the first control circuit 51 indicating an instruction to switch the mechanical relay 2 on or off. The control unit 43 instructs the first output unit 441 to switch the mechanical relay 2 on or off. The first output unit 441 switches the signal it outputs to the first control circuit 51 according to the instruction of the control unit 43. As a result, the mechanical relay 2 is switched on or off. Specifically, the first output unit 441 causes the first control circuit 51 to switch the mechanical relay 2 by outputting a Low voltage or a High voltage to the first control circuit 51.

[0067] The second output unit 442 outputs a signal to the second control circuit 52 indicating an instruction to switch the first semiconductor relay 31 on or off. The control unit 43 instructs the second output unit 442 to switch the first semiconductor relay 31 on or off. The second output unit 442 switches the signal it outputs to the second control circuit 52 according to the instruction of the control unit 43. Specifically, the second output unit 442 causes the second control circuit 52 to switch the first semiconductor relay 31 by outputting a Low voltage or a High voltage to the first control circuit 51. Note that if the microcontroller 4 is stopped, the second output unit 442 does not output a signal.

[0068] The first A / D converter 451 receives voltage information relating to the first analog voltage value from the first voltage detection unit 61. When analog voltage information is input to the first A / D converter 451, it converts the input analog voltage information into digital voltage information. The control unit 43 obtains the digital voltage information converted by the first A / D converter 451 from the first A / D converter 451.

[0069] The external output unit 46 outputs the failure determination result of the mechanical relay 2 or the first semiconductor relay 31 to a display device such as a navigation device or HMI. The control unit 43 determines whether the mechanical relay 2 or the first semiconductor relay 31 has failed based on the acquired vehicle status and the first voltage value acquired from the first A / D converter 451. If the control unit 43 determines that the mechanical relay 2 or the first semiconductor relay 31 has failed, it instructs the external output unit 46 to output the determination result. The external output unit 46 outputs the determination result to the display device according to the instruction of the control unit 43. The display device that has acquired the determination result displays the determination result. That is, if the control unit 43 determines that the mechanical relay 2 has failed, the display device will display that the mechanical relay 2 has failed, and if the control unit 43 determines that the first semiconductor relay 31 has failed, the display device will display that the first semiconductor relay 31 has failed.

[0070] The microcontroller 4 may include a communication unit that uses a communication protocol such as Ethernet (registered trademark) or CAN (Control Area Network). The microcontroller 4 may communicate with other in-vehicle ECUs via this communication unit and obtain, for example, an operating signal indicating an instruction to operate the load 13.

[0071] Figure 3 is a flowchart showing the control processing procedure by the second control circuit 52 in Embodiment 1. The second control circuit 52 acquires a signal from the microcontroller 4 (S1). The second control circuit 52 determines whether the signal acquired from the microcontroller 4 is an instruction to turn on the first semiconductor relay 31 (S2). The second control circuit 52 determines that it has acquired an instruction to turn on the first semiconductor relay 31 from the microcontroller 4 if a Hi voltage is applied, and determines that it has acquired an instruction to turn off the first semiconductor relay 31 from the microcontroller 4 if a Low voltage is applied.

[0072] If the signal is an instruction to turn on the first semiconductor relay 31 (S2: YES), the second control circuit 52 turns on the first semiconductor relay 31 (S3). If the first semiconductor relay 31 is already on in S3, the second control circuit 52 keeps the first semiconductor relay 31 in the on state.

[0073] If the signal instructs the first semiconductor relay 31 to turn off (S2:NO), the second control circuit 52 turns off the first semiconductor relay 31 (S4). If the first semiconductor relay 31 is already off in S4, the second control circuit 52 keeps the first semiconductor relay 31 in the off state. After executing S3 or S4, the second control circuit 52 returns the process to S1 and repeats the same process.

[0074] Figure 4 is a flowchart showing the control processing procedure by the microcontroller 4 in Embodiment 1. The control unit 43 of the microcontroller 4 acquires the vehicle status from the current determination unit 48 (S11). The control unit 43 determines whether the acquired vehicle status is in a normal current state or not (S12).

[0075] If the vehicle is in a normal current state (S12: YES), the control unit 43 instructs the second control circuit 52 to turn off the first semiconductor relay 31 (S13). If the first semiconductor relay 31 is already off in S13, the control unit 43 holds the first semiconductor relay 31 in the off state. The control unit 43 instructs the first control circuit 51 to turn on the mechanical relay 2 (S14). If the mechanical relay 2 is already on in S14, the control unit 43 holds the mechanical relay 2 in the on state.

[0076] The control unit 43 acquires the first voltage value detected by the first voltage detection unit 61 (S15). The control unit 43 determines whether the acquired first voltage value is equal to or greater than a predetermined value (S16).

[0077] If the first voltage value is greater than or equal to a predetermined value (S16: YES), the control unit 43 returns the process to S1. If the first voltage value is less than a predetermined value (S16: NO), the control unit 43 determines that the mechanical relay 2 is in an off state (S17). The control unit 43 outputs the determination result that the mechanical relay 2 is in an off state to the display device (S18) and terminates the process.

[0078] If the vehicle is not in a normal current state, i.e., in a low current state (S12:NO), the control unit 43 instructs the first control circuit 51 to turn off the mechanical relay 2 (S19). If the mechanical relay 2 is already off in S19, the control unit 43 keeps the mechanical relay 2 in the off state.

[0079] The control unit 43 causes the second control circuit 52 to turn on the first semiconductor relay 31 (S20). In S20, the control unit 43 causes the second control circuit 52 to turn on the first semiconductor relay 31 by stopping the output of a signal to the second control circuit 52. If the first semiconductor relay 31 is already on in S20, the control unit 43 keeps the first semiconductor relay 31 in the on state.

[0080] The control unit 43 acquires the first voltage value detected by the first voltage detection unit 61 (S21). The control unit 43 determines whether the acquired first voltage value is greater than or equal to a predetermined value (S22). The predetermined value in S22 may be the same as the predetermined value in S16, or it may be a different value.

[0081] If the first voltage value is greater than or equal to a predetermined value (S22: YES), the control unit 43 returns the process to S11. Before returning the process to S11, the control unit 43 may output a determination result indicating that the first semiconductor relay 31 is functioning normally to the display device. If the first voltage value is less than a predetermined value (S22: NO), the control unit 43 determines that the first semiconductor relay 31 is in an off state (S23). The control unit 43 causes the first control circuit 51 to turn on the mechanical relay 2 (S24). The control unit 43 outputs the determination result that the first semiconductor relay 31 is in an off state to the display device (S25) and terminates the process.

[0082] With the above configuration and processing, in the case of a low current state, current can be supplied to the load via the first semiconductor relay 31 without going through the mechanical relay 2, thereby reducing the number of times current is supplied through the mechanical relay 2. This reduces the number of contacts of the mechanical relay 2 and enables efficient power supply to the load. In the case of an off failure of the first semiconductor relay 31, it is possible to continue supplying current to the load 13 via the mechanical relay 2.

[0083] (Embodiment 2) In Embodiment 1, the number of semiconductor relays in the in-vehicle device 10 is one. However, the number of semiconductor relays in the in-vehicle device 10 may be two. The following describes the differences between Embodiment 2 and Embodiment 1. Except for the configuration described later. Other components are the same as in Embodiment 1. Therefore, the components common to Embodiment 1 include: The same reference numerals as in Embodiment 1 are used, and their descriptions are omitted.

[0084] Figure 5 is a block diagram showing the main components of the power supply system in Embodiment 2. The in-vehicle device 10 in Embodiment 2 includes a second semiconductor relay 32. The second semiconductor relay 32 is connected in series with the first semiconductor relay 31. In this embodiment, the second semiconductor relay 32 is provided upstream of the first semiconductor relay 31, but it may also be provided downstream of the first semiconductor relay 31. The second semiconductor relay 32 is, for example, an N-channel FET, and is provided such that its source is located upstream of the drain. When the first semiconductor relay 31 and the second semiconductor relay 32 are off, the first semiconductor relay 31 interrupts the current flowing from the battery power supply 11 to the load 13, and the second semiconductor relay 32 interrupts the current flowing from the load 13 to the battery power supply 11. This prevents current from flowing backward even if the devices are accidentally reversed.

[0085] In Embodiment 2, the second control circuit 52 switches the second semiconductor relay 32 on or off by applying a voltage to the gate of the second semiconductor relay 32. When a Hi voltage is applied, the second control circuit 52 turns on the first semiconductor relay 31 and the second semiconductor relay 32. When a Low voltage is applied, the second control circuit 52 turns off the first semiconductor relay 31 and the second semiconductor relay 32.

[0086] The in-vehicle device 10 in Embodiment 2 includes a second voltage detection unit 62. The second voltage detection unit detects a second voltage value at a location downstream of the second semiconductor relay 32 and upstream of the first semiconductor relay 31, that is, between the first semiconductor relay 31 and the second semiconductor relay 32. The second voltage detection unit 62 outputs the detected second voltage value to the microcontroller 4. In this embodiment, the voltage detected by the first voltage detection unit is the first voltage value.

[0087] Figure 6 is a block diagram showing the main components of the microcontroller 4 in Embodiment 2. The microcontroller 4 in Embodiment 2 includes a second A / D converter 452. Voltage information relating to the second analog voltage value is input to the second A / D converter 452 from the second voltage detection unit 62. When analog voltage information is input to the second A / D converter 452, it converts the input analog voltage information into digital voltage information. The control unit 43 acquires the digital voltage information converted by the second A / D converter 452 from the second A / D converter 452.

[0088] The control unit 43 determines whether the mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32 has failed, based on the vehicle status determined by the current determination unit 48, the first voltage value obtained from the first A / D conversion unit 451, and the second voltage value obtained from the second A / D conversion unit 452.

[0089] Figure 7 is a flowchart showing the control processing procedure by the second control circuit 52 in Embodiment 2. The second control circuit 52 acquires a signal from the microcontroller 4 (S31). The second control circuit 52 determines whether the signal acquired from the microcontroller 4 is an instruction to turn on the first semiconductor relay 31 and the second semiconductor relay 32 (S32). The second control circuit 52 determines that if a Hi voltage is applied, it has acquired an instruction from the microcontroller 4 to turn on the first semiconductor relay 31 and the second semiconductor relay 32, and if a Low voltage is applied, it has acquired an instruction from the microcontroller 4 to turn off the first semiconductor relay 31 and the second semiconductor relay 32.

[0090] If the signal is an instruction to turn on the first semiconductor relay 31 and the second semiconductor relay 32 (S32: YES), the second control circuit 52 turns on the first semiconductor relay 31 and the second semiconductor relay 32 (S33). If the first semiconductor relay 31 and the second semiconductor relay 32 are already turned on in S33, the second control circuit 52 maintains the first semiconductor relay 31 and the second semiconductor relay 32 in the turned-on state.

[0091] If the signal is an instruction to turn off the first semiconductor relay 31 and the second semiconductor relay 32 (S32: NO), the second control circuit 52 turns off the first semiconductor relay 31 and the second semiconductor relay 32 (S34). If the first semiconductor relay 31 and the second semiconductor relay 32 are already off in S34, the second control circuit 52 maintains the off state for the first semiconductor relay 31 and the second semiconductor relay 32. After executing S33 or S34, the second control circuit 52 returns the process to S31 and repeats the same process.

[0092] Figure 8 is a flowchart showing the control processing procedure by the microcontroller 4 in Embodiment 2. The processing in S41 to S48 is the same as the processing in S11 to S18 shown in Figure 4. In S43, the control unit 43 causes the second control circuit 52 to turn off the first semiconductor relay 31 and the second semiconductor relay 32.

[0093] If the vehicle is not in a normal current state in S42, i.e., in a low current state (S42:NO), the control unit 43 of the microcontroller 4 instructs the first control circuit 51 to turn off the mechanical relay 2 (S49). The control unit 43 instructs the second control circuit 52 to turn on the first semiconductor relay 31 and the second semiconductor relay 32 (S50).

[0094] The control unit 43 obtains a first voltage value from the first voltage detection unit 61 and a second voltage value from the second voltage detection unit 62 (S51). The control unit 43 determines whether the first voltage value is greater than or equal to a predetermined value (S52). If the first voltage value is greater than or equal to the predetermined value (S52: YES), the control unit 43 returns the process to S41. If the first voltage value is less than the predetermined value (S52: NO), the control unit 43 determines whether the second voltage value is greater than or equal to a predetermined value (S53). The predetermined value in S53 may be the same as the predetermined value in S46 or S52, or it may be a different value from the predetermined values ​​in S46 and S52.

[0095] If the second voltage value is greater than or equal to a predetermined value (S53: YES), the control unit 43 determines that the first semiconductor relay 31 is in an off state (S54). If the second voltage value is less than a predetermined value (S53: NO), the control unit 43 determines that the second semiconductor relay 32 is in an off state (S55). After executing S54 or S55, the control unit 43 causes the first control circuit 51 to turn on the mechanical relay 2 (S56). The control unit 43 outputs the determination result from S54 or S55 to the display device (S57) and terminates the process.

[0096] With the above configuration and processing, when the first semiconductor relay 31 and the second semiconductor relay 32 are off, no current flows from the battery power supply to the load or from the load to the battery power supply, and there is no need to provide any other mechanism to interrupt the current in the event of reverse connection. The memory unit 42 of the microcontroller 4 may store a table in its management items (fields) that includes the vehicle status, the first voltage value, the second voltage value, and the fault status. The fault status field stores the type of faulty relay. In this case, the control unit 43 may determine the fault of the mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32 by comparing the acquired vehicle status, the first voltage value and the second voltage value actually detected with the information stored in the table.

[0097] (Embodiment 3) In Embodiment 2, the second semiconductor relay 32 is connected in series with the first semiconductor relay 31. However, the second semiconductor relay 32 may also be connected in parallel with the first semiconductor relay 31. The following describes the differences between Embodiment 3 and Embodiment 2. Except for the configuration described later, all other configurations are the same as those in Embodiment 2. Therefore, components common to both Embodiment 2 and Embodiment 3 are given the same reference numerals and their descriptions are omitted.

[0098] Figure 9 is a block diagram showing the main components of the power supply system in Embodiment 3. In Embodiment 3, the second semiconductor relay 32 is connected in parallel with the first semiconductor relay 31. The second semiconductor relay 32 is, for example, an N-channel FET, and is provided such that its drain is located upstream of the source.

[0099] A first resistor 91 is provided downstream of the first semiconductor relay 31, and a second resistor 92 is provided downstream of the second semiconductor relay 32. Both ends of the first resistor 91 are connected to the fault detection circuit 9. In other words, the first resistor 91 functions as a shunt resistor.

[0100] The fault detection circuit 9 draws current from the connection node between the first semiconductor relay 31 and the first resistor 91, and outputs an analog voltage value (resistance voltage value) proportional to the voltage value across the first resistor 91 based on the drawn current. Specifically, the fault detection circuit 9 may be a circuit similar to the current detection circuit disclosed in Japanese Patent Application Publication No. 2021-109477. That is, the fault detection circuit 9 includes a variable resistor (e.g., a P-channel type FET) whose resistance value changes according to the voltage value across the first resistor 91, and outputs the voltage value after stepping down by the variable resistor as the resistance voltage value.

[0101] In Embodiment 3, the second control circuit 52, similar to Embodiment 2, turns on the first semiconductor relay 31 and the second semiconductor relay 32 when the vehicle is in a low current state.

[0102] Figure 10 is a block diagram showing the main components of the microcontroller 4 in Embodiment 3. The second A / D converter 452 of the microcontroller 4 in Embodiment 3 receives voltage information related to the analog resistance voltage value from the fault detection circuit 9. When analog voltage information is input to the second A / D converter 452, it converts the input analog voltage information into digital voltage information. The control unit 43 acquires the digital voltage information converted by the second A / D converter 452 from the second A / D converter 452.

[0103] In Embodiment 3, the memory unit 42 of the microcontroller 4 stores a lower threshold and an upper threshold as threshold values ​​related to the resistance voltage value. The lower threshold is less than the upper threshold and greater than zero. The control unit 43 of the microcontroller 4 determines whether the mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32 has failed based on the determined state of the vehicle, the first voltage value obtained from the first A / D converter 451, and the resistance voltage value obtained from the second A / D converter 452. Specifically, if the resistance voltage value is less than the lower threshold when the current is low, the control unit 43 determines that the first semiconductor relay 31 has an off failure. Also, if the resistance voltage value is greater than or equal to the upper threshold when the current is low, the control unit 43 determines that the second semiconductor relay 32 has an off failure.

[0104] Figure 11 is a flowchart showing the control processing procedure by the microcontroller 4 in Embodiment 3. Steps S61 to S68 are the same as steps S41 to S48 in Figure 8. If the vehicle is not in a normal current state, i.e., in a low current state (S62: NO), the control unit 43 of the microcontroller 4 turns off the mechanical relay 2 (S69). The control unit 43 causes the second control circuit 52 to turn on the first semiconductor relay 31 and the second semiconductor relay 32 (S70).

[0105] The control unit 43 obtains a first voltage value from the first voltage detection unit 61 (S71). The control unit 43 determines whether the first voltage value is equal to or greater than a predetermined value (S72).

[0106] If the first voltage value is less than a predetermined value (S72: NO), the control unit 43 determines that the first semiconductor relay 31 and the second semiconductor relay 32 are in an off state (S73). The control unit 43 causes the first control circuit 51 to turn on the mechanical relay 2 (S74). The control unit 43 outputs the determination result from S73 to the display device (S75) and terminates the process.

[0107] If the first voltage value is greater than or equal to a predetermined value (S72: YES), the control unit 43 obtains the resistance voltage value from the fault detection circuit 9 (S76). The control unit 43 determines whether the resistance voltage value is greater than or equal to a lower threshold (S77). If the resistance voltage value is less than the lower threshold (S77: NO), the control unit 43 determines that the first semiconductor relay 31 is in an off state (S78).

[0108] If the resistance voltage value is greater than or equal to the lower threshold (S77:YES), the control unit 43 determines whether the resistance voltage value is greater than or equal to the upper threshold (S79). If the resistance voltage value is less than the upper threshold (S79:NO), the control unit 43 returns the process to S61. If the resistance voltage value is greater than or equal to the upper threshold (S79:YES), the control unit 43 determines that the second semiconductor relay 32 is in an off state (S80).

[0109] The control unit 43 outputs the determination result from S78 or S80 to the display device (S81) and terminates the process.

[0110] With the above configuration and processing, even if either the first semiconductor relay 31 or the second semiconductor relay 32 fails to turn off, it is possible to continue supplying power to the load via the other semiconductor relay.

[0111] (Embodiment 4) In Embodiment 2, the second semiconductor relay 32 is provided such that its drain is located upstream of its source. However, the second semiconductor relay 32 may also be provided such that its source is located upstream of its drain. The following describes the differences between Embodiment 4 and Embodiment 2. Except for the configuration described later, all other configurations are the same as those in Embodiment 2. Therefore, components common to both Embodiment 4 and Embodiment 2 are given the same reference numerals and their descriptions are omitted.

[0112] Figure 12 is a block diagram showing the main components of the power supply system 1 in Embodiment 4. In Embodiment 4, the second semiconductor relay 32 of the in-vehicle device 10 is configured such that its drain is located upstream of the source and it is connected in series with the first semiconductor relay 31. In Figure 12, the second semiconductor relay 32 is located upstream of the first semiconductor relay 31, but it may also be located downstream of the first semiconductor relay 31.

[0113] Furthermore, a reverse current prevention element 7 is provided upstream of the mechanical relay 2 and the first semiconductor relay 31. This makes it possible to interrupt the current flowing from the load 13 to the battery power supply 11 in the event of an accidental reverse connection.

[0114] The configuration of the microcontroller 4, the processing by the second control circuit 52, and the processing by the microcontroller 4 in Embodiment 4 are the same as in Embodiment 2.

[0115] With the above configuration, even if one of the first semiconductor relay 31 or the second semiconductor relay 32 fails to turn off, the current can be interrupted by turning off the other semiconductor relay.

[0116] (Embodiment 5) In Embodiment 1, the first semiconductor relay 31 is an N-channel type FET. However, the first semiconductor relay 31 may also be a P-channel type FET. The following describes the differences between Embodiment 5 and Embodiment 1. Except for the configuration described later, all other configurations are the same as those in Embodiment 1. Therefore, components common to Embodiment 1 are given the same reference numerals as in Embodiment 2, and their descriptions are omitted.

[0117] Figure 13 is a block diagram showing the main components of the power supply system in Embodiment 5. The first semiconductor relay 31 of the in-vehicle device 10 in Embodiment 5 is a P-channel type FET with its source located upstream of the drain. When the vehicle is in a normal current state, the second control circuit 52 applies a voltage to the gate of the first semiconductor relay 31 that is equivalent to the voltage applied to the source of the first semiconductor relay 31, turning the first semiconductor relay 31 into an off state where no current flows. When the vehicle is in a low current state, the second control circuit 52 steps down the voltage applied to the gate of the first semiconductor relay 31, thereby allowing current to flow through the first semiconductor relay 31. on Set it to that state.

[0118] The configuration of the microcontroller 4, the processing by the second control circuit 52, and the processing by the microcontroller 4 in Embodiment 5 are the same as in Embodiment 1.

[0119] With the above configuration, the second control circuit 52 can lower the voltage applied to the gate of the first semiconductor relay 31 when the vehicle is in a low current state, It is possible to reduce the power consumption of the battery power supply 11 while the vehicle is stopped.

[0120] (modified version) In each of the embodiments described above, the control unit 43 of the microcontroller 4 determines whether the mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32 is in an off state, but is not limited to this. The control unit 43 may also determine an on state, where the mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32 does not turn off, based on the vehicle status, a first voltage value, a second voltage value, or a resistance voltage value. The control unit 43 may determine the off state and on state of the mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32 and output the faulty relay and the type of fault to a display device.

[0121] In each of the embodiments described above, the first control circuit 51 switches the mechanical relay 2 on or off, and the second control circuit 52 switches the first semiconductor relay 31 and the second semiconductor relay 32 on or off, but is not limited to this. The mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32 may be controlled to be switched on or off by the microcontroller 4. The second control circuit 52 may also switch the first semiconductor relay 31 and the second semiconductor relay 32 on or off based on a signal from the microcontroller 4.

[0122] The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the claims and scope equivalent to the claims. Furthermore, the independent and dependent claims described in the claims can be combined with each other in any combination, regardless of the form of reference. In addition, the claims use a multi-claim format in which claims refer to two or more other claims (multi-claim format), but are not limited to this. They may also be described using a multi-claim format in which at least one multi-claim refers to another multi-claim (multi-multi-claim format). [Explanation of symbols]

[0123] 1. Power System 10 Onboard equipment 11 Battery power 13 Load 2 Mechanical relays 31. First Semiconductor Relay 32. Second Semiconductor Relay 4. Microcomputer (Microcomputer) 41 Input section 42 Storage section 43 Control Unit 44 Output section 46 External Output Section 48 Current judgment section 51 First Control Circuit 52 Second Control Circuit 61 First voltage detection unit 62 Second Voltage Detection Unit 9. Fault detection circuit 91 1st resistance 92 2nd resistor A storage medium P Computer Program

Claims

1. An on-board device mounted in a vehicle that controls the supply of power to one or more loads, The condition of the aforementioned vehicle is, The vehicle is started, the power switch or ignition switch is on, or there are occupants inside the vehicle, and the load's current consumption is normal current, and When the vehicle is stopped, the power switch or ignition switch is off, or there are no occupants in the vehicle, and the load's current consumption is low, which is less than the normal current, Includes, A mechanical relay connected between the vehicle's battery power supply and the load, A first semiconductor relay connected in parallel with the aforementioned mechanical relay, A first control circuit that turns on the mechanical relay when the vehicle is in a normal current state, and turns off the mechanical relay when the vehicle is in a low current state, A second control circuit that turns off the first semiconductor relay when the vehicle is in a normal current state, and turns on the first semiconductor relay when the vehicle is in a low current state. Equipped with In-vehicle device.

2. An on-board device mounted on a vehicle that controls the supply of power to one or more loads, The state of the vehicle includes a normal current state in which the load's current consumption is normal current, and a low current state in which the load's current consumption is less than normal current. A mechanical relay connected between the vehicle's battery power supply and the load, A first semiconductor relay connected in parallel with the aforementioned mechanical relay, A first control circuit that turns on the mechanical relay when the vehicle is in a normal current state, and turns off the mechanical relay when the vehicle is in a low current state, A second control circuit that turns off the first semiconductor relay when the vehicle is in a normal current state, and turns on the first semiconductor relay when the vehicle is in a low current state, A processing unit capable of determining the state of the vehicle and Equipped with, The aforementioned processing unit, Determine the state of the vehicle, A first voltage value is obtained at a point in the current path that is downstream of the mechanical relay and the first semiconductor relay and upstream of the load. Based on the determination result of the vehicle's condition and the first voltage value, it is determined whether the mechanical relay or the first semiconductor relay has failed. If it is determined that the mechanical relay or the first semiconductor relay has failed, the determination result is output. If the vehicle is in a low-current state and it is determined that the first semiconductor relay has failed, the first control circuit will turn on the mechanical relay. In-vehicle device.

3. The system includes a processing unit capable of determining the state of the vehicle, The aforementioned processing unit, Determine the state of the vehicle, A first voltage value is obtained at a point in the current path that is downstream of the mechanical relay and the first semiconductor relay and upstream of the load. Based on the determination result of the vehicle's condition and the first voltage value, it is determined whether the mechanical relay or the first semiconductor relay has failed. If it is determined that the mechanical relay or the first semiconductor relay has failed, the determination result is output. The in-vehicle device according to claim 1.

4. The aforementioned processing unit, If it is determined that the first semiconductor relay has failed, the first control circuit is instructed to turn on the mechanical relay. The in-vehicle device according to claim 3.

5. The first semiconductor relay is an N-channel FET in which the drain is located upstream of the source in the current path. The system includes a second semiconductor relay, which is an N-channel type FET connected in series with the first semiconductor relay, and whose source is located upstream of the drain in the current path. The second control circuit turns off the second semiconductor relay when the vehicle is in a normal current state, and turns on the second semiconductor relay when the vehicle is in a low current state. The in-vehicle device according to claim 1.

6. The system includes a processing unit capable of determining the state of the vehicle, The aforementioned processing unit, Determine the state of the vehicle, A first voltage value is obtained at a point in the current path that is downstream of the mechanical relay, the first semiconductor relay, and the second semiconductor relay, and upstream of the load. The second voltage value is obtained at the point between the first semiconductor relay and the second semiconductor relay in the current path. Based on the determination result of the vehicle's condition, the first voltage value, and the second voltage value, it is determined whether the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed. If it is determined that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed, the determination result is output. The in-vehicle device according to claim 5.

7. The aforementioned processing unit, If it is determined that the first semiconductor relay or the second semiconductor relay has failed, the first control circuit is instructed to turn on the mechanical relay. The in-vehicle device according to claim 6.

8. The first semiconductor relay is connected in parallel with a second semiconductor relay, The second control circuit turns off the second semiconductor relay when the vehicle is in a normal current state, and turns on the second semiconductor relay when the vehicle is in a low current state. The in-vehicle device according to claim 1.

9. A resistor located downstream of the first semiconductor relay in the current path, A fault detection circuit that outputs a resistance voltage value that rises when the voltage value across the resistor increases, A processing unit capable of determining the state of the vehicle and Equipped with, The aforementioned processing unit, Determine the state of the vehicle, The first voltage value at a point in the current path that is downstream of the mechanical relay, the first semiconductor relay, and the second semiconductor relay and upstream of the load, and the resistance voltage value output by the fault detection circuit are obtained. Based on the determination result of the vehicle's condition, the first voltage value, and the resistance voltage value, it is determined whether the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed. If it is determined that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed, the determination result is output. The in-vehicle device according to claim 8.

10. The aforementioned processing unit, If it is determined that the first semiconductor relay and the second semiconductor relay have failed, the first control circuit is instructed to turn on the mechanical relay. The in-vehicle device according to claim 9.

11. The first semiconductor relay is an N-channel FET in which the drain is located upstream of the source in the current path. The system includes a second semiconductor relay, which is an N-channel type FET connected in series with the first semiconductor relay, and in the current path, the drain is located upstream of the source. The second control circuit turns off the second semiconductor relay when the vehicle is in a normal current state, and turns on the second semiconductor relay when the vehicle is in a low current state. The in-vehicle device according to claim 1.

12. The system includes a processing unit capable of determining the state of the vehicle, The aforementioned processing unit, Determine the state of the vehicle, A first voltage value is obtained at a point in the current path that is downstream of the mechanical relay, the first semiconductor relay, and the second semiconductor relay, and upstream of the load. The second voltage value is obtained at the point between the first semiconductor relay and the second semiconductor relay in the current path. Based on the determination result of the vehicle's condition, the first voltage value, and the second voltage value, it is determined whether the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed. If it is determined that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed, the determination result is output. The in-vehicle device according to claim 11.

13. The aforementioned processing unit, If it is determined that the first semiconductor relay or the second semiconductor relay has failed, the first control circuit is instructed to turn on the mechanical relay. The in-vehicle device according to claim 12.

14. The first semiconductor relay is a P-channel type FET in which the source is located upstream of the drain in the current path. The second control circuit turns off the first semiconductor relay by increasing the voltage applied to the gate of the first semiconductor relay when the vehicle is in a normal current state, and turns on the first semiconductor relay by decreasing the voltage applied to the gate of the first semiconductor relay when the vehicle is in a low current state. The in-vehicle device according to claim 1.

15. The system includes a processing unit capable of determining the state of the vehicle, The aforementioned processing unit, Determine the state of the vehicle, A first voltage value is obtained at a point in the current path that is downstream of the mechanical relay and the first semiconductor relay and upstream of the load. Based on the determination result of the vehicle's condition and the first voltage value, it is determined whether the mechanical relay or the first semiconductor relay has failed. If it is determined that the mechanical relay or the first semiconductor relay has failed, the determination result is output. The in-vehicle device according to claim 14.

16. The aforementioned processing unit, If it is determined that the first semiconductor relay has failed, the first control circuit is instructed to turn on the mechanical relay. The in-vehicle device according to claim 15.

17. A control method for an on-board device mounted on a vehicle that controls the supply of power to a load, The in-vehicle device is A mechanical relay connected between the battery power supply and the load, A first semiconductor relay connected in parallel with the aforementioned mechanical relay and Equipped with, The condition of the aforementioned vehicle is, The vehicle is started, the power switch or ignition switch is on, or there are occupants inside the vehicle, and the load's current consumption is normal current, and When the vehicle is stopped, the power switch or ignition switch is off, or there are no occupants in the vehicle, and the load's current consumption is low, which is less than the normal current, Includes, When the vehicle is in a normal current state, the mechanical relay is turned on. If the vehicle is in a low current state, the mechanical relay is turned off. When the vehicle is in a normal current state, the first semiconductor relay is turned off. When the vehicle is in a low current state, the first semiconductor relay is turned on. Control method.

18. A control method for an on-board device mounted on a vehicle that controls the supply of power to a load, The in-vehicle device is A mechanical relay connected between the battery power supply and the load, A first semiconductor relay connected in parallel with the aforementioned mechanical relay and Equipped with, When the vehicle is in a normal current state, the mechanical relay is turned on. If the vehicle is in a low current state, the mechanical relay is turned off. When the vehicle is in a normal current state, the first semiconductor relay is turned off. When the vehicle is in a low current state, the first semiconductor relay is turned on. Determine the state of the vehicle, A first voltage value is obtained at a point in the current path that is downstream of the mechanical relay and the first semiconductor relay and upstream of the load. Based on the determination result of the vehicle's condition and the first voltage value, it is determined whether the mechanical relay or the first semiconductor relay has failed. If it is determined that the mechanical relay or the first semiconductor relay has failed, the determination result is output. If it is determined that the first semiconductor relay has failed while the vehicle is in a low-current state, the mechanical relay is turned on. Control method.

19. The computer executes a process to control the onboard device installed in the vehicle that controls the power supply to the load. It is a program that makes it happen. The in-vehicle device is A mechanical relay connected between the battery power supply and the load, A first semiconductor relay connected in parallel with the aforementioned mechanical relay and Equipped with, The condition of the aforementioned vehicle is, The vehicle is started, the power switch or ignition switch is on, or there are occupants inside the vehicle, and the load's current consumption is normal current, and When the vehicle is stopped, the power switch or ignition switch is off, or there are no occupants in the vehicle, and the load's current consumption is low, which is less than the normal current, Includes, When the vehicle is in a normal current state, the mechanical relay is turned on. If the vehicle is in a low current state, the mechanical relay is turned off. When the vehicle is in a normal current state, the first semiconductor relay is turned off. When the vehicle is in a low current state, the first semiconductor relay is turned on. A program that instructs a computer to perform a process.

20. A computer executes a process to control an on-board device mounted on a vehicle that controls the supply of power to a load. It is a program that makes it happen. The in-vehicle device is A mechanical relay connected between the battery power supply and the load, A first semiconductor relay connected in parallel with the aforementioned mechanical relay and Equipped with, When the vehicle is in a normal current state, the mechanical relay is turned on. If the vehicle is in a low current state, the mechanical relay is turned off. When the vehicle is in a normal current state, the first semiconductor relay is turned off. When the vehicle is in a low current state, the first semiconductor relay is turned on. Determine the state of the vehicle, A first voltage value is obtained at a point in the current path that is downstream of the mechanical relay and the first semiconductor relay and upstream of the load. Based on the determination result of the vehicle's condition and the first voltage value, it is determined whether the mechanical relay or the first semiconductor relay has failed. If it is determined that the mechanical relay or the first semiconductor relay has failed, the determination result is output. If it is determined that the first semiconductor relay has failed while the vehicle is in a low-current state, the mechanical relay is turned on. A program that instructs a computer to perform a process.

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