On-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 technology]

[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 a current path of a 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 end. For example, when the semiconductor switch is a FET (Field Effect Transistor), the control end is a gate. The resistance value between both ends of the semiconductor switch changes according to the voltage at the control end. By adjusting the voltage at the control end, 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 at the control end, 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] JP 2013-143905 A Summary of the Invention [Problem 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, no consideration is given to the viewpoint of power supply using the mechanical relay and the semiconductor relay.

[0006] An object of the present disclosure is to provide an in-vehicle device or the like that is configured to include a mechanical relay and a semiconductor switch and that can efficiently supply power using the mechanical relay and the semiconductor switch. [Means for solving the problem]

[0007] An on-board device according to one embodiment of the present disclosure is an on-board device that is mounted on a vehicle and controls power supply to one or more loads, the state of the vehicle including a normal current state in which the current consumption of the load is a normal current and a low current state in which the current consumption of the load is smaller than the normal current, and the device includes a mechanical relay connected between a battery power source 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.

[0008] A control method according to one embodiment of the present disclosure is a control method for an on-board device that is mounted on a vehicle and controls power supply 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, and when the vehicle is in a normal current state, the mechanical relay is turned on, when 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, and when the vehicle is in a low current state, the first semiconductor relay is turned on.

[0009] A program according to one embodiment of the present disclosure is a program that causes a computer to execute a process for controlling an on-board device that is mounted on a vehicle and controls power supply to a load, the on-board device having 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 causes the computer to execute a process for turning on the mechanical relay when the vehicle is in a normal current state, turning off the mechanical relay when the vehicle is in a low current state, turning off the first semiconductor relay when the vehicle is in a normal current state, and turning on the first semiconductor relay when the vehicle is in a low current state. Effect of the Invention

[0010] In the in-vehicle device according to an embodiment of the present disclosure, it is possible to efficiently supply power using a mechanical relay and a semiconductor switch. [Brief description of the drawings]

[0011] [Figure 1] 1 is a block diagram showing a configuration of a main part of a power supply system according to a first embodiment. [Diagram 2] 1 is a block diagram showing a configuration of a main part of a microcomputer according to a first embodiment. [Diagram 3] 5 is a flowchart showing a control process procedure by a second control circuit in the first embodiment. [Figure 4] 4 is a flowchart showing a control process procedure performed by a microcomputer in the first embodiment. [Diagram 5] FIG. 11 is a block diagram showing the configuration of a main part of a power supply system according to a second embodiment. [Figure 6] FIG. 11 is a block diagram showing the main configuration of a microcomputer according to a second embodiment. [Figure 7] 10 is a flowchart showing a control process procedure performed by a second control circuit in the second embodiment. [Figure 8] 10 is a flowchart showing a control process procedure performed by a microcomputer in the second embodiment. [Figure 9]FIG. 11 is a block diagram showing a configuration of a main part of a power supply system according to a third embodiment. [Figure 10] FIG. 11 is a block diagram showing the configuration of a main part of a microcomputer according to a third embodiment. [Figure 11] 11 is a flowchart showing a control process procedure performed by a microcomputer in the third embodiment. [Figure 12] FIG. 11 is a block diagram showing a configuration of a main part of a power supply system according to a fourth embodiment. [Figure 13] FIG. 13 is a block diagram showing a configuration of a main part of a power supply system according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [Description of the embodiment 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 on-board device according to one embodiment of the present disclosure is an on-board device that is mounted on a vehicle and controls power supply 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 a normal current and a low current state in which the current consumption of the load is smaller than the normal current, and the on-board device includes a mechanical relay connected between a battery power source 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, the power supplied from the battery power source is supplied to the load via the in-vehicle device. That is, the in-vehicle device operates as a power supply control device. When the vehicle is started, a 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 current value of the low current is lower than the current value of the normal current, for example, 10 mA to 100 mA. The current value of the low current is a low value, for example, about one hundredth or one thousandth of the current value of the normal current. When the vehicle is stopped, the current supplied to the load of the vehicle is made low, thereby reducing consumption of the battery power source. For example, the vehicle starts when the power switch or the ignition switch is on, and stops when the power switch or the ignition switch is off. The normal current flows from the battery power source to the load via a mechanical relay provided in the in-vehicle device. Note that the vehicle may be in an embodiment in which a normal current flows to the load when there is an occupant in the vehicle, and a low current flows to the load when there is no occupant in the vehicle. When the number of times (number of contacts) that the mechanical relay is switched on or off increases, there is a concern that the deterioration of the mechanical relay will progress. When a load is operated in a low current state in which a low current flows, the number of times that a current flows through the mechanical relay can be reduced by passing a current to the load through the first semiconductor relay without passing through 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 through the load is low, so that 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, and the configuration according to this embodiment can be realized with reduced product costs. Note that a P-channel type FET, transistor, thyristor, IPD (Intelligent Power Device), or the like may be used for the first semiconductor relay.

[0015] (2) An in-vehicle device according to one embodiment of the present disclosure includes a processing unit capable of determining a state of the vehicle, wherein the processing unit determines the state of the vehicle, acquires a first voltage value at a point 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 a determination result if it is determined that the mechanical relay or the first semiconductor relay has failed.

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

[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, it causes the first control circuit to turn on the mechanical relay.

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

[0019] (4) In an in-vehicle device according to one embodiment of the present disclosure, the first semiconductor relay is an N-channel FET having a drain arranged upstream of a source in a current path, and the device further includes a second semiconductor relay connected in series with the first semiconductor relay and having a source arranged upstream of a drain in a current path, and 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 the drain is disposed upstream of the source, so that when the first semiconductor relay is off, no current flows from the battery power source to the load. However, when the first semiconductor relay is the only semiconductor relay between the power source and the load, there is a risk that a current will flow from the load to the battery power source in the event of erroneous reverse connection due to the effect of the body diode. The second semiconductor relay is an N-channel FET like the first semiconductor, but the source is disposed upstream of the drain, so that when the second semiconductor relay is off, it is possible to prevent a current from flowing from the load to the power source due to the effect of the body diode. Therefore, when the first semiconductor relay and the second semiconductor relay are off, no current flows from the battery power source to the load and from the load to the battery power source, and there is no need to provide a mechanism for blocking the current in the event of reverse connection. It should be noted that either the first semiconductor relay or the second semiconductor relay may be provided upstream.

[0021] (5) An in-vehicle device according to one embodiment of the present disclosure includes a processing unit capable of determining a state of the vehicle, wherein the processing unit determines the state of the vehicle, acquires a 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, acquires a second voltage value at a point in the current path between the first semiconductor relay and the second semiconductor relay, and determines whether or not the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed based on a result of the determination of the state of the vehicle, the first voltage value, and the second voltage value. If it is determined that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed, the processing unit outputs a determination result.

[0022] In this aspect, the processing unit acquires a first voltage between the mechanical relay and the load when the vehicle is in a normal current state, and when the acquired first voltage is less than a predetermined value, determines that an off failure occurs in which the mechanical relay does not turn on. When the vehicle is in a low current state, the processing unit acquires a first voltage between the load and a semiconductor relay downstream of the first semiconductor relay or the second semiconductor relay. In addition, the processing unit acquires a second voltage value between the first semiconductor relay and the second semiconductor relay. When both the first voltage value and the second voltage value are less than a predetermined value, the processing unit determines that the semiconductor relay arranged on the upstream side has an off failure. When 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 arranged on the downstream side has an off failure. When the processing unit determines that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has a failure, it is possible to notify the passenger that a failure has occurred by outputting a determination result.

[0023] (6) In the in-vehicle device according to one embodiment of the present disclosure, when the processing unit determines that the first semiconductor relay or the second semiconductor relay has failed, it causes 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 it becomes impossible to pass current to the load via the first semiconductor relay and the second semiconductor relay when the vehicle is in a low current state, it is possible to continue passing current to the load by turning on the mechanical relay.

[0025] (7) An in-vehicle device according to one embodiment of the present disclosure includes a second semiconductor relay connected in parallel to the first semiconductor relay, and 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 experiences an off failure when the vehicle is in a low current state, it is possible to continue flowing current from the battery power source to the load without turning on the mechanical relay.

[0027] (8) An in-vehicle device according to one embodiment of the present disclosure includes a resistor arranged downstream of the first semiconductor relay in a current path, a fault detection circuit that outputs a resistance voltage value that increases when a voltage value between both ends of the resistor increases, and a processing unit capable of determining a state of the vehicle, wherein the processing unit determines a state of the vehicle, acquires a 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, determines whether the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed based on a determination result of the state of the vehicle, the first voltage value, and the resistance voltage value, and outputs a determination result if it is determined that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed.

[0028] In this aspect, the processing unit acquires a first voltage value between the mechanical relay and the load when the vehicle is in a normal current state, and determines that the mechanical relay is not turned on due to an off-failure when 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 load and a semiconductor relay downstream of the first semiconductor relay or the second semiconductor relay. The processing unit also acquires a resistance voltage value output by the failure detection circuit. The resistance voltage value is proportional to a voltage value between both ends of the resistor, and when the voltage value between both ends of the resistor increases, the resistance voltage value also 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 exceeds zero. When the vehicle is in a low current state, if the resistance voltage value is less than the lower threshold when the first voltage value is equal to or greater than a predetermined value, the processing unit determines that the first semiconductor relay is in an off-failure. When the resistance voltage value is equal to or greater than the upper threshold when the first voltage value is equal to or greater than a predetermined value, the processing unit determines that the second semiconductor relay is in an off-failure. Furthermore, when the first voltage value acquired while the vehicle is in a low current state is less than a predetermined value, the processor determines that the first semiconductor relay and the second semiconductor relay have an off failure. When the processor determines that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed, it is possible to notify the passenger of the occurrence of the failure by outputting the determination result.

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

[0030] In this embodiment, when the first semiconductor relay and the second semiconductor relay fail to turn off and it becomes impossible to pass current to the load through the first semiconductor relay or the second semiconductor relay while the vehicle is in a low current state, it is possible to continue passing current to the load by turning on the mechanical relay.

[0031] (10) In one embodiment of the in-vehicle device of the present disclosure, the first semiconductor relay is an N-channel FET having a drain arranged upstream of a source in a current path, and the second semiconductor relay is connected in series with the first semiconductor relay and is an N-channel FET having a drain arranged upstream of a source in a current path, and 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, the first semiconductor relay and the second semiconductor relay are both N-channel FETs in which the drain is disposed upstream of the source, and the first semiconductor relay and the second semiconductor relay are connected in series. If there is only one semiconductor relay, the current cannot be cut off in the event of an on-fault in which the semiconductor relay does not turn off. By connecting the first semiconductor relay and the second semiconductor relay in series, even if an on-fault occurs in one of them, it is possible to cut off the current by turning off the other.

[0033] (11) An in-vehicle device according to one embodiment of the present disclosure includes a processing unit capable of determining a state of the vehicle, wherein the processing unit determines the state of the vehicle, acquires a 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, acquires a second voltage value at a point in the current path between the first semiconductor relay and the second semiconductor relay, determines whether or not the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed based on a result of the determination of the state of the vehicle, the first voltage value, and the second voltage value, and outputs a determination result if it is determined that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed.

[0034] In this aspect, the processing unit acquires a first voltage between the mechanical relay and the load when the vehicle is in a normal current state, and when the acquired first voltage is less than a predetermined value, determines that an off failure occurs in which the mechanical relay does not turn on. When the vehicle is in a low current state, the processing unit acquires a first voltage between the load and a semiconductor relay downstream of the first semiconductor relay or the second semiconductor relay. In addition, the processing unit acquires a second voltage value between the first semiconductor relay and the second semiconductor relay. When both the first voltage value and the second voltage value are less than a predetermined value, the processing unit determines that the semiconductor relay arranged on the upstream side has an off failure. When 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 has an off failure. When the processing unit determines that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has a failure, it is possible to notify the passenger that a failure has occurred by outputting a determination result.

[0035] (12) In the in-vehicle device according to one aspect of the present disclosure, when the processing unit determines that the first semiconductor relay or the second semiconductor relay has failed, it causes 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 it becomes impossible to pass current to the load via the first semiconductor relay and the second semiconductor relay when the vehicle is in a low current state, it is possible to continue passing current to the load by turning on the mechanical relay.

[0037] (13) In an in-vehicle device according to one embodiment of the present disclosure, the first semiconductor relay is a P-channel FET having a source arranged upstream of a drain in a current path, and the second control circuit turns off the first semiconductor relay by increasing a voltage applied to a 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 FET, and the second control circuit, when in a normal current state, is capable of keeping the first semiconductor relay in an off state by applying a voltage equivalent to the voltage applied to the source of the first semiconductor relay to the gate using a current from the battery power source. Also, when the vehicle is in a low current state, the second control circuit is capable of turning on the first semiconductor relay by lowering the voltage applied to the gate of the first semiconductor relay. This makes it possible to lower the voltage applied to the gate of the first semiconductor relay when the vehicle is in a low current state, thereby reducing the power consumption of the battery power source while the vehicle is stopped.

[0039] (14) An in-vehicle device according to one embodiment of the present disclosure includes a processing unit capable of determining a state of the vehicle, wherein the processing unit determines the state of the vehicle, acquires a first voltage value at a point 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 a determination result if it is determined that the mechanical relay or the first semiconductor relay has failed.

[0040] In this aspect, the processing unit, when the vehicle is in a normal current state, acquires a first voltage value between the mechanical relay and the load, and when the acquired first voltage value is less than a predetermined value, determines that an off failure has occurred in which the mechanical relay 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 when the acquired first voltage value is less than a predetermined value, determines that an off failure has occurred in which the first semiconductor relay does not turn on. When the processing unit determines that the mechanical relay or the first semiconductor relay has failed, it is possible to notify the passenger that a failure has occurred by outputting a determination result.

[0041] (15) 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, it causes 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 pass current to the load through the first semiconductor relay when the vehicle is in a low current state, it is possible to continue passing current to the load by turning on the mechanical relay.

[0043] (16) A control method according to one embodiment of the present disclosure is a control method for an on-board device that is mounted on a vehicle and controls power supply to a load, the on-board device including 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 on-board device 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 the normal current state, and turns on the first semiconductor relay when the vehicle is in a low current state.

[0044] In this embodiment, power can be efficiently supplied using a mechanical relay and a semiconductor switch.

[0045] (17) A program according to one embodiment of the present disclosure is a program that causes a computer to execute a process for controlling an on-board device that is mounted on a vehicle and controls power supply to a load, the on-board device having 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 causes the computer to execute a process for turning on the mechanical relay when the vehicle is in a normal current state, turning off the mechanical relay when the vehicle is in a low current state, turning off the first semiconductor relay when the vehicle is in the normal current state, and turning on the first semiconductor relay when the vehicle is in a low current state.

[0046] In this embodiment, power can be efficiently supplied using a mechanical relay and a semiconductor switch.

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

[0048] (Embodiment 1) FIG. 1 is a block diagram showing a main configuration of a power supply system 1 in the first embodiment. In FIG. 1, current lines are indicated by solid lines, and signal lines are indicated by dashed lines. The power supply system 1 is mounted on a vehicle, and includes an in-vehicle device 10, a battery power supply 11, and a load 13. The battery power supply 11 is a power supply that outputs a direct current. The in-vehicle device 10 is connected to a positive electrode of the battery power supply 11 and one end of a plurality of loads 13. The in-vehicle device 10 is, for example, an ECU (Electronic Control Unit) that controls a current from the battery power supply 11 to the load 13. The negative electrode of the battery power supply 11 and the other end of the load 13 are grounded. In the following description, in the current path from the battery power supply 11 to the load 13, the battery power supply 11 side is the upstream of the current, and the load 13 side is the downstream of the current.

[0049] When the vehicle is started, the battery power supply 11 supplies a current (normal current) for operating the load. When the vehicle is stopped, the battery power supply 11 supplies a low-current power whose current value is lower than the normal current. The load 13 to which the low-current power is supplied is a load that needs to be operated even when the vehicle is stopped, such as an interior light or a security device. The microcomputer 4 can determine whether the vehicle is in a normal current state or a low-current state based on the current value (load current value) of the power supplied to the multiple loads 13. The microcomputer 4 may also determine whether the vehicle is in a normal current state or a low-current state based on the current value passed from the battery power supply 11 to the in-vehicle device.

[0050] The load 13 is an electric device. When power is supplied to the load 13, the load 13 operates. When power supply to the load 13 is stopped, the load 13 stops operating. Note that the number of loads 13 connected to the in-vehicle device 10 is not limited to one, and multiple loads 13 may be connected to the in-vehicle device 10.

[0051] The in-vehicle device 10 includes a mechanical relay 2, a first semiconductor relay 31, a microcomputer 4, a first control circuit 51, a second control circuit 52, a first voltage detection unit 61, a backflow prevention element 7, a fusing element 8, and a pull-up resistor R. These are installed on a common substrate. Note that some of the above-mentioned components may be installed outside the in-vehicle device 10.

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

[0053] In this embodiment, the first semiconductor relay 31 is, for example, an N-channel type FET. The first semiconductor relay 31 is arranged between the battery power supply 11 and the load 13 so as to be connected in parallel with the mechanical relay 2. The first semiconductor relay 31 is also connected to a current path so that the drain is arranged upstream of the source. The first semiconductor relay 31 is turned on when a voltage is applied to the gate from the second control circuit 52, and is turned off when the application of the voltage to the gate is stopped. When the first semiconductor relay 31 is on, a 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 to the coil 21 of the mechanical relay 2. The first control circuit 51 is, for example, an electronic device such as a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or an application specific standard product (ASSP). The first control circuit 51 may be a software processing unit such as a microcomputer or a digital signal processor (DSP). When a signal (Hi voltage) indicating an instruction to turn on the mechanical relay 2 is input from the microcomputer 4, the first control circuit 51 turns on the mechanical relay 2 by supplying power to the coil 21 of the mechanical relay 2. When a signal (Low voltage) indicating an instruction to turn off the mechanical relay 2 is input from the microcomputer 4 or when no signal is input, the first control circuit 51 turns off the mechanical relay 2 by stopping the current 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, for example, an electronic device such as an FPGA, an ASIC, or an ASSP. The second control circuit 52 may be a software processing unit such as a microcomputer or a DSP. When a signal (Low voltage) indicating an instruction to turn off the first semiconductor relay 31 is input from the microcomputer 4, the second control circuit 52 does not apply a voltage to the gate of the first semiconductor relay 31 and turns off the first semiconductor relay 31. When a Hi voltage is input, the second control circuit 52 assumes that a signal indicating an instruction to turn on the first semiconductor relay 31 is input from the microcomputer 4, and applies a voltage to the gate of the first semiconductor relay 31 to turn on the first semiconductor relay 31.

[0056] The pull-up resistor R is connected to the battery power source 11 and a signal line from the microcomputer 4 to the second control circuit 52. When the microcomputer 4 stops operating during 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 microcomputer 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 microcomputer 4 stops operating, a voltage equivalent to the case where the microcomputer 4 outputs a signal indicating an instruction to turn on the first semiconductor relay 31 is applied to the second control circuit 52. As a result, even when the operation of the microcomputer 4 is stopped, the second control circuit 52 can control the first semiconductor relay 31. The second control circuit 52 may be configured by an IPD integrally with the first semiconductor relay 31. In this case, it is possible to reduce the power consumed in a low current state compared to when the second control circuit 52 is controlled by the microcomputer 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. That is, 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 microcomputer 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 cuts off the current flowing from the load 13 to the battery power supply 11 in the event of erroneous reverse connection.

[0059] The fusing element 8 is a fuse or a fusible link, etc. One fusing element 8 is provided downstream of the mechanical relay 2 and the first semiconductor relay 31 and upstream of each load 13. When a current equal to or greater than a reference current flows through the fusing element 8, the fusing element 8 melts. When a current equal to or greater than the reference current flows, the fusing element 8 melts, thereby protecting the mechanical relay 2 and the first semiconductor relay 31.

[0060] 2 is a block diagram showing the main configuration of the microcomputer 4 in the embodiment 1. The microcomputer 4 has 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 a sum of current values ​​(load current value) of power supplied to the multiple loads 13. The input unit 41 may also receive a current value (device current value) flowing from the battery power source 11 to the in-vehicle device. 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 storage unit 42 is a non-volatile memory. The storage unit 42 stores a computer program P (program product). The control unit 43 has a processing element that executes processing, for example, a CPU (Central Processing Unit), and functions as a processing unit. The processing element of the control unit 43 executes the computer program P to execute a process of causing the first control circuit 51 to switch the mechanical relay 2 on or off, a process of causing the second control circuit 52 to switch the first semiconductor relay 31 on or off, a process of determining a fault in the mechanical relay 2 or the first semiconductor relay 31, and a process of outputting a fault determination result of the mechanical relay 2 or the first semiconductor relay 31.

[0063] The computer program P may be stored in the storage medium A so that the processing element of the control unit 43 can read it. 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 disk, a flexible disk, a magnetic disk, a magneto-optical disk, a semiconductor memory, or the like. The optical disk is a CD (Compact Disc)-ROM (Read Only Memory), a DVD (Digital Versatile Disc)-ROM, a BD (Blu-ray (registered trademark) Disc), or the like. The magnetic disk is, for example, a hard disk. The computer program P may also 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] The storage unit 42 also stores a threshold value (state threshold value) for the current determination unit 48 to determine the state of the vehicle, a predetermined value for determining whether the mechanical relay 2 or the first semiconductor relay 31 has failed, and the like.

[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 out the 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 determine the state of the vehicle based on the current value (device current value) flowing from the battery power source 11 to the in-vehicle device. The current determination unit 48 may execute the above-mentioned process using a processing element such as a CPU, for example, and may be configured as one functional unit of the control unit 43. The current determination unit 48 may execute the above-mentioned process using an analog element such as a comparator.

[0066] The first output unit 441 outputs a signal indicating an instruction to switch the mechanical relay 2 on or off to the first control circuit 51. 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 to be output to the first control circuit 51 in accordance with the instruction of the control unit 43. This switches the mechanical relay 2 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 Hi voltage to the first control circuit 51.

[0067] The second output unit 442 outputs a signal indicating an instruction to switch the first semiconductor relay 31 on or off to the second control circuit 52. 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 to be output to the second control circuit 52 in accordance with the instruction of the control unit 43. Specifically, the second output unit 442 outputs a Low voltage or a Hi voltage to the first control circuit 51, thereby causing the second control circuit 52 to switch the first semiconductor relay 31. Note that when the microcomputer 4 is stopped operating, the second output unit 442 does not output a signal.

[0068] The first A / D conversion unit 451 receives voltage information related to the analog first voltage value from the first voltage detection unit 61. When the first A / D conversion unit 451 receives analog voltage information, the first A / D conversion unit 451 converts the input analog voltage information into digital voltage information. The control unit 43 acquires the digital voltage information converted by the first A / D conversion unit 451 from the first A / D conversion unit 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 an HMI. The control unit 43 determines whether or not the mechanical relay 2 or the first semiconductor relay 31 has failed based on the acquired vehicle state and the first voltage value acquired from the first A / D conversion unit 451. When 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, when the control unit 43 determines that the mechanical relay 2 has failed, the display device displays a message that the mechanical relay 2 has failed, and when the control unit 43 determines that the first semiconductor relay 31 has failed, the display device displays a message that the first semiconductor relay 31 has failed.

[0070] The microcomputer 4 may include a communication unit that uses a communication protocol such as Ethernet (registered trademark) or CAN (Control Area Network). The microcomputer 4 may communicate with another vehicle-mounted ECU via the communication unit and obtain, for example, an actuation signal indicating an instruction to actuate the load 13.

[0071] 3 is a flowchart showing a control process procedure by the second control circuit 52 in the first embodiment. The second control circuit 52 acquires a signal from the microcomputer 4 (S1). The second control circuit 52 determines whether or not the signal acquired from the microcomputer 4 is an instruction to turn on the first semiconductor relay 31 (S2). When a Hi voltage is applied, the second control circuit 52 determines that an instruction to turn on the first semiconductor relay 31 is acquired from the microcomputer 4, and when a Low voltage is applied, the second control circuit 52 determines that an instruction to turn off the first semiconductor relay 31 is acquired from the microcomputer 4.

[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). Note that 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 is an instruction to turn off the first semiconductor relay 31 (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] 4 is a flowchart showing a control process procedure by the microcomputer 4 in the embodiment 1. The control unit 43 of the microcomputer 4 acquires the vehicle state from the current determination unit 48 (S11). The control unit 43 determines whether the acquired vehicle state is a normal current state or not (S12).

[0075] If the vehicle is in a normal current state (S12: YES), the control unit 43 causes 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 causes 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 equal to or greater than the predetermined value (S16: YES), the control unit 43 returns the process to S1. If the first voltage value is less than the predetermined value (S16: NO), the control unit 43 determines that the mechanical relay 2 has an OFF fault (S17). The control unit 43 outputs the determination result that the mechanical relay 2 has an OFF fault to the display device (S18), and ends the process.

[0078] If the vehicle is not in a normal current state, that is, if the vehicle is in a low current state (S12: NO), the control unit 43 causes the first control circuit 51 to turn off the mechanical relay 2 (S19). Note that 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 stops outputting a signal to the second control circuit 52, thereby causing the second control circuit 52 to turn on the first semiconductor relay 31. Note that 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 equal to or greater than a predetermined value (S22). Note that the predetermined value in S22 may be the same as the predetermined value in S16, or may be a different value.

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

[0082] According to the above configuration and processing, in a low current state, it is possible to reduce the number of times that current is passed through the mechanical relay 2 by passing current to the load through the first semiconductor relay 31 rather than through the mechanical relay 2. This reduces the number of contacts of the mechanical relay 2 and makes it possible to supply power to the load efficiently. Note that, if the first semiconductor relay 31 has an OFF failure, it is possible to continue passing current to the load 13 through the mechanical relay 2.

[0083] (Embodiment 2) In the first embodiment, the in-vehicle device 10 has one semiconductor relay. However, the in-vehicle device 10 may have two semiconductor relays. The following describes the second embodiment and the differences from the first embodiment. The rest of the configuration is the same as in the first embodiment. Therefore, the components common to the first embodiment include: The same reference symbols as in the first embodiment are used and their explanations are omitted.

[0084] FIG. 5 is a block diagram showing a main configuration of a power supply system in the second embodiment. The in-vehicle device 10 in the second embodiment 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 on the upstream side of the first semiconductor relay 31, but may be provided on the downstream side of the first semiconductor relay 31. The second semiconductor relay 32 is, for example, an N-channel type FET, and is provided so that the source is disposed on the upstream side with respect to the drain. When the first semiconductor relay 31 and the second semiconductor relay 32 are off, the first semiconductor relay 31 cuts off the current flowing from the battery power supply 11 to the load 13, and the second semiconductor relay 32 cuts off the current flowing from the load 13 to the battery power supply 11. This makes it possible to prevent the current from flowing backwards even if the two are erroneously connected in reverse.

[0085] The second control circuit 52 in the second embodiment 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 the second embodiment includes a second voltage detection unit 62. The second voltage detection unit detects a second voltage value downstream of the second semiconductor relay 32 and upstream of the first semiconductor relay 31, i.e., a second voltage value at a location 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 microcomputer 4. Note that in this embodiment, the voltage detected by the first voltage detection unit is the first voltage value.

[0087] 6 is a block diagram showing a main configuration of the microcomputer 4 in the second embodiment. The microcomputer 4 in the second embodiment includes a second A / D conversion unit 452. The second A / D conversion unit 452 receives voltage information related to the analog second voltage value from the second voltage detection unit 62. When analog voltage information is received, the second A / D conversion unit 452 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 conversion unit 452 from the second A / D conversion unit 452.

[0088] The control unit 43 determines whether or not the mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32 has failed based on the state of the vehicle determined by the current determination unit 48, the first voltage value acquired from the first A / D conversion unit 451, and the second voltage value acquired from the second A / D conversion unit 452.

[0089] 7 is a flowchart showing a control process procedure by the second control circuit 52 in the second embodiment. The second control circuit 52 acquires a signal from the microcomputer 4 (S31). The second control circuit 52 determines whether the signal acquired from the microcomputer 4 is an instruction to turn on the first semiconductor relay 31 and the second semiconductor relay 32 (S32). When a Hi voltage is applied, the second control circuit 52 determines that an instruction to turn on the first semiconductor relay 31 and the second semiconductor relay 32 is acquired from the microcomputer 4, and when a Low voltage is applied, the second control circuit 52 determines that an instruction to turn off the first semiconductor relay 31 and the second semiconductor relay 32 is acquired from the microcomputer 4.

[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). Note that if the first semiconductor relay 31 and the second semiconductor relay 32 are already on in S33, the second control circuit 52 keeps the first semiconductor relay 31 and the second semiconductor relay 32 in the 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). Note that, if the first semiconductor relay 31 and the second semiconductor relay 32 are already off in S34, the second control circuit 52 keeps the first semiconductor relay 31 and the second semiconductor relay 32 in the off state. After executing S33 or S34, the second control circuit 52 returns the process to S31 and repeats the same process.

[0092] Fig. 8 is a flowchart showing a control process procedure by the microcomputer 4 in embodiment 2. The processes in S41 to S48 are similar to the processes in S11 to S18 shown in Fig. 4. In addition, 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 the normal current state in S42, i.e., in the low current state (S42: NO), the control unit 43 of the microcomputer 4 causes the first control circuit 51 to turn off the mechanical relay 2 (S49). The control unit 43 causes 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 or not the first voltage value is equal to or greater than a predetermined value (S52). If the first voltage value is equal to or greater than 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 or not the second voltage value is equal to or greater than a predetermined value (S53). Note that the predetermined value in S53 may be the same as the predetermined value in S46 or S52, or may be a value different from the predetermined values ​​in S46 and S52.

[0095] If the second voltage value is equal to or greater than the predetermined value (S53: YES), the control unit 43 determines that the first semiconductor relay 31 has an OFF failure (S54). If the second voltage value is less than the predetermined value (S53: NO), the control unit 43 determines that the second semiconductor relay 32 has an OFF failure (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 in S54 or S55 to the display device (S57), and ends the process.

[0096] According to 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 source to the load and from the load to the battery power source, and there is no need to provide a mechanism for cutting off the current in the case of reverse connection. The storage unit 42 of the microcomputer 4 may store a table including the vehicle state, the first voltage value, the second voltage value, and the fault state in the management items (fields). The type of the faulty relay is stored in the fault state field. 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 collating the acquired vehicle state and the actually detected first voltage value and second voltage value with the information stored in the table.

[0097] (Embodiment 3) In the second embodiment, the second semiconductor relay 32 is connected in series with the first semiconductor relay 31. However, the second semiconductor relay 32 may 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 below, the configuration is the same as embodiment 2. Therefore, the components common to embodiment 2 are given the same reference numerals as embodiment 2, and the description thereof will be omitted.

[0098] 9 is a block diagram showing a configuration of a main part of a power supply system according to embodiment 3. The second semiconductor relay 32 according to embodiment 3 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 the drain is disposed 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. That is, the first resistor 91 functions as a shunt resistor.

[0100] The fault detection circuit 9 draws in a 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 between both ends of 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 JP 2021-109477 A. That is, the fault detection circuit 9 includes a variable resistor (e.g., a P-channel FET) whose resistance value changes depending on the voltage value between both ends of the first resistor 91, and outputs the voltage value after being stepped down by the variable resistor as the resistance voltage value.

[0101] Similar to the second embodiment, the second control circuit 52 in the third embodiment turns on the first semiconductor relay 31 and the second semiconductor relay 32 when the vehicle is in a low current state.

[0102] 10 is a block diagram showing a configuration of a main part of the microcomputer 4 in the third embodiment. Voltage information relating to an analog resistance voltage value is input from the fault detection circuit 9 to the second A / D conversion unit 452 of the microcomputer 4 in the third embodiment. When analog voltage information is input, the second A / D conversion unit 452 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 conversion unit 452 from the second A / D conversion unit 452.

[0103] The storage unit 42 of the microcomputer 4 in the third embodiment stores a lower threshold and an upper threshold as thresholds related to the resistance voltage value. The lower threshold is less than the upper threshold and exceeds zero. The control unit 43 of the microcomputer 4 determines whether the mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32 has failed based on the determined vehicle state, the first voltage value acquired from the first A / D conversion unit 451, and the resistance voltage value acquired from the second A / D conversion unit 452. Specifically, when the resistance voltage value is less than the lower threshold in a low current state, the control unit 43 determines that the first semiconductor relay 31 has an off failure. Also, when the resistance voltage value is equal to or greater than the upper threshold in a low current state, the control unit 43 determines that the second semiconductor relay 32 has an off failure.

[0104] Fig. 11 is a flowchart showing a control process procedure by the microcomputer 4 in the third embodiment. Steps S61 to S68 are similar to steps S41 to S48 in Fig. 8. If the vehicle is not in the normal current state in S62, that is, in the low current state (S62: NO), the control unit 43 of the microcomputer 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 acquires a first voltage value from the first voltage detection unit 61 (S71). The control unit 43 determines whether or not the first voltage value is equal to or greater than a predetermined value (S72).

[0106] If the first voltage value is less than the predetermined value (S72: NO), the control unit 43 determines that the first semiconductor relay 31 and the second semiconductor relay 32 have an OFF failure (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 in S73 to the display device (S75) and ends the process.

[0107] If the first voltage value is equal to or greater than the predetermined value (S72: YES), the control unit 43 acquires a resistance voltage value from the fault detection circuit 9 (S76). The control unit 43 determines whether the resistance voltage value is equal to or greater than 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 has an off fault (S78).

[0108] If the resistance voltage value is equal to or greater than the lower threshold (S77: YES), the control unit 43 determines whether the resistance voltage value is equal to or greater than 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 equal to or greater than the upper threshold (S79: YES), the control unit 43 determines that the second semiconductor relay 32 has an OFF failure (S80).

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

[0110] According to the above configuration and processing, even if one of the first semiconductor relay 31 or the second semiconductor relay 32 experiences an OFF fault, it is possible to continue supplying power to the load via the other semiconductor relay.

[0111] (Embodiment 4) In the second embodiment, the second semiconductor relay 32 is provided such that the drain is disposed upstream of the source. However, the second semiconductor relay 32 may be provided such that the source is disposed upstream of the drain. The following describes the differences between embodiment 4 and embodiment 2. Except for the configuration described below, the configuration is the same as embodiment 2. Therefore, the components common to embodiment 2 are given the same reference numerals as embodiment 2, and the description thereof will be omitted.

[0112] Fig. 12 is a block diagram showing a configuration of a main part of a power supply system 1 according to embodiment 4. The second semiconductor relay 32 of the in-vehicle device 10 according to embodiment 4 is provided so that the drain is disposed upstream of the source and is connected in series with the first semiconductor relay 31. In Fig. 12, the second semiconductor relay 32 is provided upstream of the first semiconductor relay 31, but may be provided downstream of the first semiconductor relay 31.

[0113] In addition, 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 cut off the current flowing from the load 13 to the battery power supply 11 in the event of erroneous reverse connection.

[0114] The configuration of the microcomputer 4, the processing by the second control circuit 52, and the processing by the microcomputer 4 in the fourth embodiment are similar to those in the second embodiment.

[0115] According to the above configuration, even if an on-fault occurs in which one of the first semiconductor relay 31 or the second semiconductor relay 32 does not turn off, it is possible to interrupt the current by turning off the other semiconductor relay.

[0116] (Embodiment 5) In the first embodiment, the first semiconductor relay 31 is an N-channel FET. However, the first semiconductor relay 31 may be a P-channel FET. The following describes the differences between embodiment 5 and embodiment 1. Except for the configuration described below, the configuration is the same as embodiment 1. Therefore, the components common to embodiment 1 are given the same reference numerals as embodiment 2, and the description thereof will be omitted.

[0117] 13 is a block diagram showing a configuration of a main part of a power supply system according to the fifth embodiment. The first semiconductor relay 31 of the in-vehicle device 10 according to the fifth embodiment is a P-channel FET in which the source is provided upstream of the drain. When the vehicle is in a normal current state, the second control circuit 52 applies a voltage equivalent to the voltage applied to the source of the first semiconductor relay 31 to the gate, thereby turning the first semiconductor relay 31 off so that no current flows. When the vehicle is in a low current state, the second control circuit 52 lowers the voltage applied to the gate of the first semiconductor relay 31 to turn the first semiconductor relay 31 off so that current flows.

[0118] The configuration of the microcomputer 4, the processing by the second control circuit 52, and the processing by the microcomputer 4 in the fifth embodiment are similar to those in the first embodiment.

[0119] According to the above-mentioned configuration, the second control circuit 52 can reduce 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] (Modification) In each of the above-described embodiments, the control unit 43 of the microcomputer 4 determines whether the mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32 has an OFF failure, but this is not limited to the above. The control unit 43 may determine an ON failure in which the mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32 does not turn off based on the vehicle state, the first voltage value, the second voltage value, or the resistance voltage value. The control unit 43 may determine an OFF failure or an ON failure of the mechanical relay 2, the first semiconductor relay 31, or the second semiconductor relay 32, and output the failed relay and the type of failure to a display device.

[0121] In each of the above-described embodiments, 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 this is not limited to the above. 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 microcomputer 4. Furthermore, the second control circuit 52 may switch the first semiconductor relay 31 and the second semiconductor relay 32 on or off based on a signal from the microcomputer 4.

[0122] The embodiments disclosed herein should be considered to be illustrative in all respects 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 scope of the claims and equivalents to the scope of the claims. In addition, the independent claims and dependent claims described in the claims can be combined with each other in all combinations regardless of the reference format. Furthermore, the claims use a format in which a claim references two or more other claims (multiple claim format), but this is not limited to this. A format in which a multiple claim (multi-multi claim) that references at least one multiple claim may be used. [Explanation of symbols]

[0123] 1 Power System 10 Onboard equipment 11 Battery Power 13 Load 2. Mechanical Relays 31 First solid-state relay 32 Second semiconductor relay 4. 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 in-vehicle device that is mounted on a vehicle and controls power supply to one or more loads, the state of the vehicle includes a normal current state in which the current consumption of the load is a normal current, and a low current state in which the current consumption of the load is smaller than the normal current; a mechanical relay connected between a battery power source 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 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 In-vehicle device.

2. A processing unit capable of determining a state of the vehicle, The processing unit includes: determining a state of the vehicle; acquiring a first voltage value at a point in a current path that is downstream of the mechanical relay and the first semiconductor relay and upstream of the load; determining whether or not the mechanical relay or the first semiconductor relay has failed based on the result of the determination of the vehicle state and the first voltage value; When it is determined that the mechanical relay or the first semiconductor relay has failed, a determination result is output. The in-vehicle device according to claim 1 .

3. The processing unit includes: When it is determined that the first semiconductor relay has failed, the first control circuit causes the mechanical relay to be turned on. The vehicle-mounted device according to claim 2 .

4. the first semiconductor relay is an N-channel FET having a drain disposed upstream of a source in a current path, a second semiconductor relay which is an N-channel FET connected in series with the first semiconductor relay and has a source disposed upstream of a drain in a 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 .

5. A processing unit capable of determining a state of the vehicle, The processing unit includes: determining a state of the vehicle; acquiring a first voltage value at a point downstream of the mechanical relay, the first semiconductor relay, and the second semiconductor relay and upstream of the load in a current path; acquiring a second voltage value at a point between the first semiconductor relay and the second semiconductor relay in a current path; determining whether or not the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed based on the result of the determination of the state of the vehicle, the first voltage value, and the second voltage value; When it is determined that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed, a determination result is output. The vehicle-mounted device according to claim 4.

6. The processing unit includes: When it is determined that the first semiconductor relay or the second semiconductor relay has failed, the first control circuit causes the mechanical relay to be turned on. The vehicle-mounted device according to claim 5 .

7. a second semiconductor relay connected in parallel to the first 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 .

8. A resistor disposed downstream of the first semiconductor relay in a current path; a fault detection circuit that outputs a resistor voltage value that increases when the voltage value across the resistor increases; A processing unit capable of determining a state of the vehicle; Equipped with The processing unit includes: determining a state of the vehicle; acquiring a first voltage value at a point downstream of the mechanical relay, the first semiconductor relay, and the second semiconductor relay and upstream of the load in a current path, and the resistance voltage value output by the fault detection circuit; determining whether or not the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed based on the result of the determination of the vehicle state, the first voltage value, and the resistance voltage value; When it is determined that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed, a determination result is output. The vehicle-mounted device according to claim 7.

9. The processing unit includes: When it is determined that the first semiconductor relay and the second semiconductor relay have failed, the first control circuit causes the mechanical relay to be turned on. The in-vehicle device according to claim 8.

10. the first semiconductor relay is an N-channel FET having a drain disposed upstream of a source in a current path, a second semiconductor relay which is an N-channel FET connected in series with the first semiconductor relay and has a drain disposed upstream of a source in a 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 .

11. A processing unit capable of determining a state of the vehicle, The processing unit includes: determining a state of the vehicle; acquiring a first voltage value at a point downstream of the mechanical relay, the first semiconductor relay, and the second semiconductor relay and upstream of the load in a current path; acquiring a second voltage value at a point between the first semiconductor relay and the second semiconductor relay in a current path; determining whether or not the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed based on the result of the determination of the state of the vehicle, the first voltage value, and the second voltage value; When it is determined that the mechanical relay, the first semiconductor relay, or the second semiconductor relay has failed, a determination result is output. The in-vehicle device according to claim 10.

12. The processing unit includes: When it is determined that the first semiconductor relay or the second semiconductor relay has failed, the first control circuit causes the mechanical relay to be turned on. The in-vehicle device according to claim 11.

13. the first semiconductor relay is a P-channel FET having a source disposed upstream of a drain in a current path; The second control circuit turns off the first semiconductor relay by increasing a voltage applied to a gate of the first semiconductor relay when the vehicle is in a normal current state, and turns on the first semiconductor relay by decreasing a 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 .

14. A processing unit capable of determining a state of the vehicle, The processing unit includes: determining a state of the vehicle; acquiring a first voltage value at a point in a current path that is downstream of the mechanical relay and the first semiconductor relay and upstream of the load; determining whether or not the mechanical relay or the first semiconductor relay has failed based on the result of the determination of the vehicle state and the first voltage value; When it is determined that the mechanical relay or the first semiconductor relay has failed, a determination result is output. The in-vehicle device according to claim 13.

15. The processing unit includes: When it is determined that the first semiconductor relay has failed, the first control circuit causes the mechanical relay to be turned on. The in-vehicle device according to claim 14.

16. A method for controlling an in-vehicle device that is mounted on a vehicle and controls power supply to a load, comprising: The in-vehicle device includes: a mechanical relay connected between the battery power source and the load; a first semiconductor relay connected in parallel with the mechanical relay; Equipped with When the vehicle is in a normal current state, turning on the mechanical relay; turning off the mechanical relay when the vehicle is in a low current state; When the vehicle is in a normal current state, turning off the first semiconductor relay; When the vehicle is in a low current state, turn on the first semiconductor relay. Control methods.

17. A program for causing a computer to execute a process for controlling an in-vehicle device that is mounted on a vehicle and controls power supply to a load, The in-vehicle device includes: a mechanical relay connected between the battery power source and the load; a first semiconductor relay connected in parallel with the mechanical relay; Equipped with When the vehicle is in a normal current state, turning on the mechanical relay; turning off the mechanical relay when the vehicle is in a low current state; When the vehicle is in a normal current state, turning off the first semiconductor relay; When the vehicle is in a low current state, turn on the first semiconductor relay. A program that causes a computer to carry out processing.

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