On-board device

Abstract

An on-board device according to the present disclosure comprises: a plurality of opening / closing devices that are provided in parallel with a power line from a power source device mounted in a vehicle; a control unit that controls the output of power of each of the opening / closing devices to a downstream side in a flow direction of a current from the power source device by applying voltage to each of the opening / closing devices; a first determination circuit that is provided to each of the opening / closing devices, and that outputs a first determination result indicating whether or not the application state of the voltage applied to the opening / closing device by the control unit corresponds to the output state of the power output to the downstream side by the opening / closing device; and a second determination circuit that outputs a second determination result obtained by determining whether all of the first determination results output by the plurality of first determination circuits indicate that the application state corresponds to the output state. The control unit acquires the second determination result from the second determination circuit, and determines the presence or absence of an opening / closing device which is in a failure state among the plurality of opening / closing devices on the basis of the acquired second determination result.

Description

In-vehicle device

[0001] This application claims priority to Japanese Patent Application No. 2023-200167, filed November 27, 2023, and incorporates by reference all of the contents of said Japanese application.

[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] A semiconductor switch has a control end. For example, if the semiconductor switch is a FET (Field Effect Transistor), the control end is a gate. The resistance value across the semiconductor switch varies depending on the voltage at the control end. By adjusting the voltage at the control end, the resistance value across the semiconductor switch is adjusted to a sufficiently small value, and the semiconductor switch is turned on. By adjusting the voltage at the control end, the resistance value across the semiconductor switch is adjusted to a sufficiently large value, and the semiconductor switch is turned off.

[0004] JP 2013-143905 A

[0005] An in-vehicle device according to one embodiment of the present disclosure includes a plurality of opening / closing devices arranged in parallel to a power line from a power supply device mounted on a vehicle; a control unit that applies a voltage to each of the opening / closing devices to control the output of power from each of the opening / closing devices to the downstream side in the direction of current flow from the power supply device; a first determination circuit that is provided in each of the opening / closing devices and outputs a first determination result indicating whether the state of voltage applied to the opening / closing device by the control unit corresponds to the state of power output from the opening / closing device to the downstream side; and a second determination circuit that outputs a second determination result that determines whether all of the first determination results output by each of the plurality of first determination circuits indicate correspondence, and the control unit acquires the second determination result from the second determination circuit and, based on the acquired second determination result, determines whether any of the plurality of opening / closing devices is in a faulty state.

[0006] 1 is a block diagram showing a configuration of a main part of an in-vehicle device according to a first embodiment. FIG. 2 is a block diagram showing an example configuration of a microcomputer of the in-vehicle device according to the first embodiment. FIG. 3 is a timing chart showing inputs and outputs of a first determination circuit according to a second embodiment. FIG. 4 is a flowchart showing the procedure of a failure determination process according to the second embodiment. FIG. 5 is a block diagram showing a configuration of a main part of an in-vehicle device according to a third embodiment. FIG. 6 is a timing chart showing inputs and outputs of a first determination circuit according to the third embodiment. FIG. 7 is a block diagram showing a configuration of a main part of an in-vehicle device according to a fourth embodiment. FIG. 8 is a timing chart showing inputs and outputs of a first determination circuit according to the fourth embodiment. FIG. 9 is a block diagram showing a configuration of a main part of a power supply system according to a fifth embodiment. FIG. 10 is a block diagram showing an example connection between a microcomputer and an IPD of the in-vehicle device according to the fifth embodiment. FIG. 11 is a flowchart showing the procedure of a failure determination process according to the fifth embodiment.

[0007] [Problem to be Solved by the Present Disclosure] However, the power supply control device of Document 1 does not take into consideration the viewpoint of efficiently determining the fault state of the switchgear.

[0008] The present disclosure has been made in consideration of the above circumstances, and aims to provide an in-vehicle device or the like that can efficiently determine a fault state of a switching device.

[0009] Effect of the Present Disclosure An in-vehicle device according to an embodiment of the present disclosure can efficiently determine a fault state of a switching device.

[0010] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. At least some of the embodiments described below may be combined in any combination.

[0011] (1) An in-vehicle device according to one aspect of the present disclosure includes a plurality of opening / closing devices arranged in parallel to a power line from a power supply device mounted on a vehicle; a control unit that applies a voltage to each of the opening / closing devices to control the output of power from each of the opening / closing devices to the downstream side in the direction of current flow from the power supply device; a first determination circuit that is arranged in each of the opening / closing devices and outputs a first determination result indicating whether the state of voltage applied to the opening / closing device by the control unit corresponds to the state of power output from the opening / closing device to the downstream side; and a second determination circuit that outputs a second determination result that determines whether all of the first determination results output by each of the plurality of first determination circuits indicate correspondence, and the control unit acquires the second determination result from the second determination circuit and, based on the acquired second determination result, determines whether any of the plurality of opening / closing devices is in a faulty state.

[0012] In this aspect, the switching device is, for example, an intelligent power device (IPD). When a voltage is applied from the control unit, the switching device outputs power supplied from an upstream power supply device to a load connected downstream. That is, the switching device functions as a switch that switches the power output to the load based on the state of the voltage applied from the control unit. The switching device may experience fault conditions, including an open-circuit fault state in which the switching device does not output power to the downstream side despite being applied a high-level voltage from the control unit, or a short-circuit fault state in which the switching device outputs power to the downstream side despite being applied a low-level voltage lower than the high-level voltage from the control unit. One first determination circuit is provided for each of the switching devices included in the on-board device. The first determination circuit determines whether the state of voltage applied from the control unit to each switching device corresponds (matches) with the state of power output from each switching device to the downstream side, and outputs the determination result (first determination result) to the second determination circuit. The second determination circuit receives the first determination results from each of the first determination circuits. The second determination circuit determines whether all of the first determination results input from each of the multiple first determination circuits indicate that the state of voltage application from the control unit to each switching device corresponds to the state of power output by each switching device to the downstream side, and outputs the determination result (second determination result) to the control device. That is, if all of the switching devices equipped with first determination circuits connected to the second determination circuit are not in a fault state, the second determination result is output, indicating that all of the first determination results indicate the correspondence. If at least one of the multiple switching devices equipped with first determination circuits connected to the second determination circuit is in a fault state, the second determination result is output, indicating that at least one of the first determination results indicates the non-correspondence. If the second determination result obtained from the second determination circuit indicates that all of the first determination results indicate the correspondence, the control unit can determine that all of the switching devices equipped with first determination circuits connected to the second determination circuit are not in a fault state.Furthermore, when the second determination result obtained from the second determination circuit indicates that at least one of the first determination results indicates incompatibility, the control unit can determine that one of the multiple switching devices, each having a first determination circuit connected to the second determination circuit, is in a fault state. Since the control unit can determine whether or not a switching device is in a fault state based solely on the second determination result, the control unit can efficiently determine the fault state of the switching device. In other words, a microcomputer including the control unit does not need to have pin terminals (PINs) corresponding to each of the multiple first determination circuits. By using pin terminals to which the second determination results from the second determination circuit are input, an increase in the number of terminals (pins) required for the microcomputer or the like can be suppressed.

[0013] (2) In an in-vehicle device according to one aspect of the present disclosure, the first determination circuit is connected to a control line connecting the control unit and the switching device and a power line connecting the switching device and a downstream load, and acquires the voltage application state from the control line and the power output state from the power line.

[0014] In this aspect, the control unit is connected to the switchgear via one pin terminal and a control line, and the control unit applies a voltage to the switchgear via the control line. The switchgear is connected to a load via a power line. The switchgear outputs power supplied from an upstream power supply to a downstream load. The first determination circuit is connected to the control line connecting the control unit and the switchgear, and is capable of acquiring an application status indicating whether the control unit is applying a low-level voltage or a high-level voltage to the switchgear. The first determination circuit is also connected to the power line connecting the switchgear and the load, and is capable of acquiring a power output status indicating whether the voltage value of the power output by the switchgear is higher than a predetermined threshold. As described above, the control unit is connected to one switchgear via one pin terminal (PIN). Furthermore, one second determination circuit is provided for each of the multiple switchgears, and the control unit is connected to the second determination circuit via one pin terminal. Because the first control circuit acquires the power output status from the power line, the control unit does not need to acquire the power output status of all switchgears, and the control line for acquiring the power output status is not connected to a pin terminal of the microcomputer equipped with the control unit. This reduces the number of pin terminals used to connect one switching device to a microcomputer equipped with a control unit, making it possible to connect a large number of switching devices to the control unit.

[0015] (3) In an in-vehicle device according to one aspect of the present disclosure, the first determination circuit outputs a low-level voltage indicating that the voltage application state corresponds to the power output state if, when the control unit applies a high-level voltage to the opening / closing device, the voltage value of the power output by the opening / closing device to the downstream side is higher than a predetermined threshold, or when the control unit applies a low-level voltage to the opening / closing device, the voltage value of the power output by the opening / closing device to the downstream side is equal to or lower than the predetermined threshold; and outputs a high-level voltage indicating that the voltage application state does not correspond to the power output state if, when the control unit applies a high-level voltage to the opening / closing device, the voltage value of the power output by the opening / closing device to the downstream side is equal to or lower than the predetermined threshold, or when the control unit applies a low-level voltage to the opening / closing device, the voltage value of the power output by the opening / closing device to the downstream side is higher than the predetermined threshold.

[0016] In this aspect, the first determination circuit is configured with an exclusive OR circuit (XOR circuit), and when the level of the voltage applied to the switchgear by the control unit matches the level of the voltage value of the power output by the switchgear to the downstream side relative to a threshold, the first determination circuit outputs a low-level voltage as the first determination result. Furthermore, when the level of the voltage applied to the switchgear by the control unit does not match the level of the voltage value of the power output by the switchgear to the downstream side relative to a threshold, the first determination circuit outputs a high-level voltage as the first determination result. Thus, when the switchgear is in a fault state, the first determination circuit can output a high-level voltage as the first determination result indicating that the applied voltage state and the output power state do not correspond.

[0017] (4) In an in-vehicle device according to one aspect of the present disclosure, the second determination circuit acquires each of the voltages output by the plurality of first determination circuits, and if all of the voltages acquired from the first determination circuits are low-level voltages, outputs a low-level voltage to the control unit, and if at least one of the voltages acquired from the first determination circuits is high-level voltage, outputs a high-level voltage to the control unit.

[0018] In this aspect, the second determination circuit is configured with a logical sum circuit (OR circuit), and when all of the voltages (first determination results) acquired from the plurality of first determination circuits are low-level voltages, the second determination circuit outputs a low-level voltage (a signal indicating that all of the first determination results correspond) to the control unit as the second determination result. Furthermore, when at least one of the voltages (first determination results) acquired from the plurality of first determination circuits is high-level voltage, the second determination circuit outputs a high-level voltage (a signal indicating that at least one of the first determination results does not correspond) to the control unit as the second determination result. This allows the second determination circuit to output a high-level voltage to the control unit when at least one of the switching devices in which the first determination circuits connected to the second determination circuit are provided is in a fault state.

[0019] (5) In an in-vehicle device according to one aspect of the present disclosure, when a high-level voltage is input from the second judgment circuit, the control unit determines that at least one of the plurality of opening and closing devices is in a fault state.

[0020] In this aspect, when at least one of the switching devices provided with the first determination circuit connected to the second determination circuit is in a fault state, the second determination circuit outputs a high-level voltage to the control unit as the second determination result, so that the control unit can determine whether or not any switching device is in a fault state based only on the second determination result obtained from the second determination circuit.

[0021] (6) In an in-vehicle device according to one aspect of the present disclosure, the control unit acquires the voltage output by the second judgment circuit at a predetermined period, and if the voltage acquired from the second judgment circuit is a high-level voltage a predetermined number of times or more in succession, determines that at least one of the multiple opening and closing devices is in a faulty state.

[0022] In this aspect, after the control unit applies a high-level voltage to the switching device, the switching device outputs power downstream. Therefore, a time difference (turn-on delay time or turn-off delay time) occurs between the time when the first determination circuit acquires the voltage application state and the time when it acquires the power output state due to the switching characteristics of the switching device. Even when the switching device is in a normal state, the application state and the output state do not match during the period from when the first determination circuit acquires the voltage application state to when it acquires the power output state, so the first control circuit outputs a high-level voltage. Accordingly, the second determination circuit also outputs a high-level voltage for the time difference. Therefore, the control unit may acquire a high-level voltage from the second determination circuit even when there is no switching device in a faulty state. Note that when there is no switching device in a faulty state, the time for which the second determination circuit outputs a high-level voltage is very short. Therefore, the control unit periodically acquires the voltage output by the second determination circuit at a predetermined time interval, and if the acquired voltage is a high-level voltage a predetermined number of times or more in succession, i.e., if a high-level voltage is output from the second determination circuit for a predetermined period of time or more, the control unit determines that at least one of the switching devices provided with the first determination circuit connected to the second determination circuit is in a fault state. This makes it possible for the control unit to prevent or reduce erroneous determinations that a switching device is in a fault state when no switching device is in a fault state.

[0023] (7) An in-vehicle device according to an aspect of the present disclosure includes a time constant increasing circuit that increases a time constant of an input of a voltage application state to the first determination circuit.

[0024] In this aspect, after the control unit applies a high-level voltage to the switching device, the switching device outputs power downstream, resulting in a time lag between the time the first determination circuit acquires the voltage application status and the time it acquires the power output status. Even when the switching device is in a normal state, the application status and the output status do not match between the time the first determination circuit acquires the voltage application status and the time it acquires the power output status, causing the first control circuit to output a high-level voltage. By providing an RC filter (time constant increasing circuit) composed of, for example, a resistor and a capacitor, between the control line through which the control unit applies voltage to the switching device and the first determination circuit, it is possible to increase the time constant of the voltage application status signal input to the first determination circuit. This slows the rise or fall of the voltage application status signal input to the first determination circuit, thereby shortening the time it takes the first control circuit to output a high-level voltage. This makes it possible to prevent or reduce erroneous determinations by the control unit that a switching device is in a faulty state when no switching device is in a faulty state. The time constant increasing circuit may be, for example, a coil.

[0025] (8) An in-vehicle device according to one aspect of the present disclosure includes a time constant increasing circuit that increases a time constant of the output of the first determination result from the first determination circuit.

[0026] In this embodiment, after the control unit applies a high-level voltage to the switching device, the switching device outputs power downstream, resulting in a time lag between when the first determination circuit acquires the voltage application status and when it acquires the power output status. Even when the switching device is in a normal state, the application status and output status do not match between when the first determination circuit acquires the voltage application status and when it acquires the power output status, causing the first control circuit to output a high-level voltage. By providing an RC filter (time constant increasing circuit) composed of, for example, a resistor and a capacitor between the first determination circuit and the second determination circuit, the rise or fall of the signal (voltage) indicating the first determination result output by the first control circuit and input to the second determination circuit becomes slow (low responsive), thereby shortening the time during which the high-level voltage is input to the second determination circuit. This makes it possible to prevent or reduce erroneous determinations by the control unit that a switching device is in a faulty state when no switching device is in a faulty state. Note that the time constant increasing circuit may, for example, use a coil.

[0027] (9) In the in-vehicle device according to one aspect of the present disclosure, the first determination circuit is configured by an exclusive OR circuit, and the second determination circuit is configured by an OR circuit.

[0028] In this aspect, the first determination circuit is configured with an exclusive OR circuit (XOR circuit), and the second determination circuit is configured with an OR circuit (OR circuit). This makes it possible to determine the presence or absence of a faulty switching device with a less expensive configuration than when determining the presence or absence of a faulty switching device using software processing alone. Note that the first determination circuit and the second determination circuit may be configured as an integrated circuit, or may be configured in an integrated circuit (hardware processing unit) such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0029] (10) In one aspect of the in-vehicle device of the present disclosure, the control unit acquires the second judgment result and determines whether at least one of the multiple opening and closing devices is in a faulty state based on the second judgment result.If it is determined that at least one of the opening and closing devices is in a faulty state, the control unit acquires a current value corresponding to the power output downstream from the opening and closing device and determines whether the opening and closing device is in a faulty state based on the voltage application state to the opening and closing device, the current value acquired from the opening and closing device, and the input current value of the power supplied from the power supply device.

[0030] In this aspect, when the control unit determines that at least one of the switching devices, each including a first determination circuit connected to the second determination circuit, is in a fault state, the control unit determines whether each switching device is in a fault state based on the voltage applied to each switching device and the current value corresponding to the power output by each switching device. Note that if a switching device is in a fault state, a current detection terminal that detects a current value corresponding to the power output downstream may also be damaged, and the current value acquired by the control unit from the switching device may not match the current value of the power actually output downstream by the switching device. The control unit can determine whether the switching device is in a fault state even if the current detection terminal of the switching device is damaged by determining whether the current value of the power supplied to the in-vehicle device (input current value) corresponds to the current value acquired from the switching device. This allows the control unit to identify the switching device in a fault state. Note that the control unit may also acquire a voltage value converted from the current value transmitted by the switching device using a pull-down resistor and determine whether the switching device is in a fault state based on the acquired voltage value.

[0031] [Details of the embodiment of the present disclosure] Specific examples of a power supply control device according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0032] (Embodiment 1) Fig. 1 is a block diagram showing the main configuration of an on-vehicle device 3 according to embodiment 1. In Fig. 1, power lines are indicated by solid lines and control lines are indicated by dashed lines. The on-vehicle device 3 is, for example, an individual ECU (Electronic Control Unit) mounted on a vehicle M. The on-vehicle device 3 may be a left-zone ECU mounted in the left zone of the vehicle M or a right-zone ECU mounted in the right zone. The on-vehicle device 3 is connected to the positive electrode of a power supply device 1 and one end of a load 4. The negative electrode of the power supply device 1 and the other end of the load 4 are grounded. In the following description, in the current path from the power supply device 1 to the load 4, the power supply device 1 side is referred to as the upstream side of the current, and the load 4 side is referred to as the downstream side of the current.

[0033] The in-vehicle device 3 includes a microcomputer (MCU) 31, a plurality of IPDs (Intelligent Power Devices) 32, first determination circuits 33 equal in number to the IPDs 32, and second determination circuits 34. The in-vehicle device 3 may also include a plurality of second determination circuits. The IPDs 32 correspond to a switching device, and the MCU 31 controls the output of power downstream of the IPDs 32 by applying a high-level voltage or a low-level voltage lower than the high-level voltage, and obtains a second determination result from the second determination circuit. Details of the second determination result will be described later.

[0034] In this embodiment, the in-vehicle device 3 includes three IPDs 32, IPDs 32a to 32c. However, the in-vehicle device 3 may include two, four, or more IPDs 32. The IPDs 32 receive power from the power supply device 1 and control the power output to the load 4 based on the voltage applied from the microcomputer 31. Specifically, the IPDs 32 include, for example, an N-channel field effect transistor (FET). The drain of the FET is connected to the power supply device 1, and the source is connected to the load 4. The gate of the FET is connected to the microcomputer 31, and the voltage applied to the IPD 32 is applied to the gate of the FET. As a result, when a high-level voltage is applied to the IPD 32, the IPD 32 outputs power to the downstream load 4. On the other hand, when a low-level voltage is applied to the IPD 32, the IPD 32 does not output power to the downstream load 4. The switching device (IPD 32) may be configured using a P-channel FET, a mechanical relay, or the like.

[0035] The in-vehicle device 3 includes three first determination circuits, 33a to 33c. One first determination circuit 33 is provided for each IPD 32. The first determination circuit 33 is connected to a control line connecting the microcomputer 31 and the IPD 32 and a power line connecting the IPD 32 and the load 4. The first determination circuit acquires, from the control line connecting the microcomputer 31 and the IPD 32, a voltage application state indicating whether the microcomputer 31 is applying a high-level voltage or a low-level voltage to the IPD 32. The first control circuit also acquires, from the power line connecting the IPD 32 and the load 4, a power output state indicating whether the voltage value of the power output by the IPD 32 to the load 4 is higher than a predetermined threshold.

[0036] The first determination circuit outputs a high-level voltage or a low-level voltage to the second determination circuit 34 as a first determination result indicating whether the acquired voltage application state and power output state correspond to each other. Specifically, when the microcomputer 31 applies a high-level voltage to the IPD 32 and the voltage value of the power output from the IPD 32 to the downstream side is higher than a predetermined threshold, or when the microcomputer 31 applies a low-level voltage to the IPD 32 and the voltage value of the power output from the IPD 32 to the downstream side is equal to or lower than the predetermined threshold, the first determination circuit 33 outputs a low-level voltage indicating that the voltage application state and power output state correspond to each other. When the microcomputer 31 applies a high-level voltage to the IPD 32 and the voltage value of the power output from the IPD 32 to the downstream side is equal to or lower than a predetermined threshold, or when the microcomputer 31 applies a low-level voltage to the IPD 32 and the voltage value of the power output from the IPD 32 to the downstream side is higher than the predetermined threshold, the first determination circuit 33 outputs a high-level voltage indicating that the voltage application state and the power output state do not correspond. That is, the first determination circuit is configured by an exclusive OR (XOR) circuit.

[0037] In this embodiment, the in-vehicle device 3 includes the same number of first determination circuits 33 as the IPDs 32, but the number of first determination circuits 33 may be different from the number of IPDs 32. In other words, there may be an IPD 32 that does not include a first determination circuit 33.

[0038] The second determination circuit 34 acquires the first determination results from each of the multiple first determination circuits 33a to 33c. The second determination circuit 34 may acquire the first determination results from two, four, or more first determination circuits 33. In this embodiment, the in-vehicle device 3 includes one second determination circuit 34, and all of the first determination circuits 33 included in the in-vehicle device 3 are connected to the single second determination circuit 34, but this is not limited to this. The in-vehicle device 3 may also be configured to include multiple second determination circuits 34, and each of the multiple first determination circuits 33 may be connected to one of the second determination circuits 34.

[0039] Based on the first determination results acquired from the first determination circuits 33a to 33c, the second determination circuit 34 outputs to the microcomputer 31 a second determination result indicating whether all of the first determination results indicate that the voltage application state and power output state of the IPD 32 correspond to each other. Specifically, if all of the first determination circuits 33a to 33c connected to the second determination circuit 34 output a low-level voltage, the second determination circuit 34 outputs a low-level voltage. If at least one of the first determination circuits 33a to 33c outputs a high-level voltage, the second determination circuit 34 outputs a high-level voltage. That is, the second determination circuit 34 is configured as a logical sum circuit (OR circuit). As a result, if all of the first determination results acquired by the second determination circuit 34 indicate that the voltage application state and power output state of the IPD 32 correspond to each other, the second determination circuit 34 outputs a low-level voltage indicating that all of the first determination results indicate that the application state and output state correspond to each other. Furthermore, if at least one of the first judgment results obtained by the second judgment circuit 34 indicates that the voltage application state and the power output state of the IPD 32 do not correspond, the second judgment circuit 34 outputs a high-level voltage indicating that at least one of the first judgment results indicates that the application state and the output state do not correspond.

[0040] 2 is a block diagram showing an example of the configuration of the microcomputer 31 of the in-vehicle device 3 according to embodiment 1. The microcomputer 31 includes a control unit 311, a storage unit 312, and an input / output I / F 313. These are connected to an internal bus 315.

[0041] The control unit 311 has a processing element, such as a CPU (Central Processing Unit), that executes processing, and functions as a processing unit. The processing element of the control unit 311 reads and executes a computer program P stored in the storage unit 312, thereby executing processing to control the output of power to the downstream side of each IPD 32 and processing to determine whether or not any IPD 32 is in a faulty state. Note that the processing executed by the control unit 311 may be executed by an external device connected to the in-vehicle device 3 wirelessly or via a wire.

[0042] The storage unit 312 is a non-volatile memory. A computer program P is stored in the storage unit 312. The computer program P may be provided to the microcomputer 31 using a non-transitory storage medium A on which the computer program P is readably recorded. The storage medium A is, for example, a portable memory. If the storage medium A is a portable memory, the processing element of the control unit 311 may read the computer program P from the storage medium A using a reading device (not shown). The read computer program P is stored in the storage unit 312. Furthermore, the computer program P may be provided to the microcomputer 31 by a communication unit (not shown) of the microcomputer 31 communicating with an external device. The storage unit 312 also stores thresholds and coefficients, which will be described later. The thresholds and coefficients stored in the storage unit 312 may be changed by reprogramming, for example, depending on the load 4 connected to the in-vehicle device 3 or the type of IPD 32 provided in the in-vehicle device 3. The thresholds and coefficients stored in the storage unit 312 may also be updated through communication with an external device.

[0043] The input / output I / F 313 is connected to the plurality of IPDs 32 via control lines. The input / output I / F 313 switches the voltage applied (output) to the IPDs 32 between a high-level voltage and a low-level voltage in accordance with an instruction from the control unit 311. The input / output I / F 313 also receives as input the second determination result output by the second determination circuit 34. The control unit 311 acquires the second determination result input to the input / output I / F 313.

[0044] The input / output I / F 313 of the microcomputer 31 has a plurality of pin terminals (PIN(1), PIN(2), ... PIN(n)). In this embodiment, the IPD 32a is connected to PIN(1) of the microcomputer 31 via a control line. The IPD 32b is connected to PIN(2) of the microcomputer 31 via a control line. The IPD 32c is connected to PIN(3) of the microcomputer 31 via a control line. When the number of IPDs 32 is three, the second determination circuit 34 is connected to, for example, PIN(4) of the microcomputer 31 via a control line, but the pin terminal to which the second determination circuit 34 is connected is not limited to this.

[0045] The control unit 311 of the microcomputer 31 applies voltage to the IPDs 32a to 32c via PINs (1) to (3) and controls the output of power to the load 4 downstream of the IPDs 32a to 32c. The control unit 311 also acquires the second judgment result output from the second judgment circuit 34 via PIN (4) and determines whether any of the IPDs 32a to 32c is in a faulty state based on the acquired second judgment result. Specifically, if a low-level voltage is output from the second judgment circuit, the control unit 311 determines that no IPD 32 is in a faulty state. If a high-level voltage is output from the second judgment circuit, the control unit 311 determines that any of the IPDs 32a to 32c is in a faulty state. In other words, the control unit 311 can determine whether any of the three IPDs 32 is in a faulty state based on the output or input from the four pin terminals. When the control unit 311 determines that any of the IPDs 32 is in a faulty state, the control unit 311 may transmit, for example, to the power supply device 1, a signal requesting the power supply device 1 to stop power supply to the in-vehicle device 3. Furthermore, the control unit 311 may execute a process of identifying the IPD 32 in a faulty state.

[0046] According to the above configuration, the control unit 311 of the microcomputer 31 can determine whether or not the IPD 32 is in a faulty state based on the voltage indicating the second determination result output from the second determination circuit 34. Furthermore, the microcomputer 31 can determine whether or not the IPD 32 is in a faulty state based on inputs and outputs at the same number of pin terminals as the IPDs 32 and at the pin terminals to which the second determination circuit 34 is connected. This reduces the number of pin terminals used to connect one IPD 32, and allows a large number of IPDs 32 to be connected to the microcomputer 31. This allows the control unit 311 to efficiently determine the faulty state of the switching device (IPD 32).

[0047] (Embodiment 2) The control unit 311 of the microcomputer 31 according to embodiment 2 acquires, at a predetermined cycle, a voltage indicating the second determination result output by the second determination circuit 34, and if the acquired voltage is a high-level voltage a predetermined number of times or more in succession, determines that at least one IPD 32 among the IPDs 32a to 32c is in a fault state. Differences between embodiment 2 and embodiment 1 will be described below. Except for the configuration described below, the other configurations are common to embodiment 1. Therefore, components common to embodiment 1 are assigned the same reference numerals as embodiment 1, and descriptions thereof will be omitted.

[0048] 3 is a timing chart showing the input and output of the first determination circuit 33 according to the second embodiment. The first determination circuit 33 receives a voltage indicating the state of voltage application from the microcomputer 31 to the IPD 32 and a voltage value of the power output from the IPD 32 indicating the state of power output from the IPD 32 to the downstream load 4. If the voltage value of the power input to the first determination circuit 33 is higher than a predetermined threshold, a high-level voltage is input to the first determination circuit 33. If the voltage value of the power is equal to or lower than the predetermined threshold, a low-level voltage is input to the first determination circuit 33. That is, the voltage value of the power input to the first determination circuit 33 is converted into a binary value before being input.

[0049] The first determination circuit 33 outputs a low-level voltage as the first state determination result when high-level voltages are input as both the power application state and the power output state, or when low-level voltages are input as both the power application state and the power output state, i.e., when the power application state and the power output match and correspond. Also, when high-level and low-level voltages are input as the power application state or the power output state, i.e., when the power application state and the power output do not match and correspond, the first determination circuit outputs a high-level voltage as the first state determination result.

[0050] When the IPD 32 is not in a fault state, if the voltage applied by the microcomputer 31 is switched from a low-level voltage to a high-level voltage, the IPD 32 starts outputting power. Furthermore, if the voltage applied by the microcomputer 31 is switched from a high-level voltage to a low-level voltage, the IPD 32 starts outputting power. Because the IPD 32 switches between outputting and not outputting power after the applied voltage is switched, a time lag occurs between the point in time when a change in the voltage input to the first determination circuit indicating the applied state of the voltage is detected (application point) and the point in time when a change in the voltage indicating the output state of the power is detected (output point), and the output point is delayed relative to the application point. During the time from the application point to the output point, the power application state and the power output do not match, and the first determination circuit outputs a high-level voltage as the first determination result, even though the IPD 32 is not in a fault state.

[0051] When the first determination circuit 33 outputs a high-level voltage, the second determination circuit 34 outputs a high-level voltage to the microcomputer 31 as the second determination result. Therefore, the control unit 311 of the microcomputer 31 may obtain a high-level voltage as the second determination result even when no IPD 32 is in a faulty state. Therefore, the control unit 311 of the microcomputer 31 obtains a voltage indicating the second determination result at a predetermined cycle, and if the obtained voltage is a high-level voltage a predetermined number of times or more in succession, determines that at least one IPD 32 among the IPDs 32a to 32c is in a faulty state. The predetermined cycle is, for example, a cycle with an interval equal to the time difference between the application time and the output time (the turn-on time or turn-off time due to the switching characteristics of the IPD 32). In this case, the predetermined number of times is two. That is, if the voltage obtained as the second determination result is a high-level voltage two times in succession, the control unit 311 determines that one of the IPDs 32a to 32c is in a faulty state. The predetermined period and the predetermined number of times are not limited to those described above, and the shorter the predetermined period, the greater the predetermined number of times.

[0052] 4 is a flowchart showing the procedure of the fault determination process according to the second embodiment. The control unit 311 of the microcomputer 31 acquires a voltage indicating the second determination result output from the second determination circuit 34 (S1). The control unit 311 determines whether the voltage indicating the second determination result is a high-level voltage (S2). If the voltage indicating the second determination result is not a high-level voltage (S2: NO), the control unit 311 returns to S1 and acquires the voltage indicating the second determination result again. Note that the voltage acquisition in S1 is performed at a predetermined cycle. If the voltage indicating the second determination result is a high-level voltage (S2: YES), the control unit 311 determines whether the acquired voltage is a high-level voltage a predetermined number of times in succession (S3). If the acquired voltage is not a high-level voltage a predetermined number of times in succession (S3: NO), the control unit 311 returns to S1. If the acquired voltage is a high-level voltage for a predetermined number of consecutive times (S3: YES), the control unit 311 determines that one of the IPDs 32a to 32c is in a faulty state (there is an IPD 32 in a faulty state) (S4), and terminates the processing.

[0053] According to the above processing, even if there is no IPD 32 in a faulty state and the control unit 311 of the microcontroller 31 obtains a high-level voltage as the second judgment result, it is possible to prevent or reduce the erroneous judgment that any of the IPDs 32 is in a faulty state.

[0054] (Embodiment 3) An in-vehicle device 3 according to embodiment 3 includes a time constant increasing circuit that increases the time constant of the input of the voltage application state from the microcomputer 31 to the IPD 32 to the first determination circuit 33. Differences between embodiment 3 and embodiment 1 will be described below. Except for the configuration described below, the other configurations are common to embodiment 1. Therefore, components common to embodiment 1 are assigned the same reference numerals as embodiment 1, and descriptions thereof will be omitted.

[0055] 5 is a block diagram showing the configuration of a main part of an in-vehicle device 3 according to embodiment 3. The in-vehicle device 3 according to embodiment 3 includes a time constant increasing circuit 35 provided for each first determination circuit 33. The time constant increasing circuit 35 is configured with a resistor 351 and a capacitor 352, and is provided between the control line connecting the microcomputer 31 and the IPD 32 and the first determination circuit 33. That is, the time constant increasing circuit is configured with an RC filter.

[0056] FIG. 6 is a timing chart showing the input and output of the first determination circuit 33 according to the third embodiment. The time constant increasing circuit 35 increases the time constant when the voltage indicating the voltage application state to the IPD 32, which is input to the first determination circuit 33, is switched, thereby slowing the rise or fall of the signal indicating the voltage. The first determination circuit 33 determines that a high-level voltage has been input when the voltage value indicating the application state exceeds a predetermined value (e.g., the average value of the low-level voltage and the high-level voltage), and determines that a low-level voltage has been input when the voltage value indicating the application state falls below the predetermined value. As a result, the application time (the time when the switching of the applied voltage is detected) is delayed compared to when the time constant increasing circuit 35 is not provided (see FIG. 3), and the time difference between the application time and the output time is shortened. When the IPD 32 is not in a fault state, the first determination circuit outputs a high-level voltage for a shorter period of time, and accordingly, the second determination circuit 34 outputs a high-level voltage to the microcomputer 31 for a shorter period of time.

[0057] According to the above configuration, when the IPD 32 is not in a faulty state, it is possible to shorten the time during which the voltage indicating the second determination result, which is acquired by the control unit 311 of the microcomputer 31 from the second determination circuit 34, is at a high level. This makes it possible to prevent or reduce the number of times that the control unit 311 of the microcomputer 31 erroneously determines that any of the IPDs 32 is in a faulty state when there is no IPD 32 in a faulty state.

[0058] (Fourth embodiment) The in-vehicle device 3 according to the fourth embodiment includes a time constant increasing circuit that increases the time constant of the voltage output indicating the first determination result from the first determination circuit 33. Differences between the first embodiment and the fourth embodiment will be described below. Except for the configuration described below, the fourth embodiment is identical to the first embodiment. Therefore, components that are identical to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and descriptions thereof will be omitted.

[0059] 7 is a block diagram showing the main configuration of an in-vehicle device 3 according to embodiment 4. The in-vehicle device 3 according to embodiment 3 includes a time constant increasing circuit 35 provided for each first determination circuit 33. The time constant increasing circuit 35 is configured with a resistor 351 and a capacitor 352, and is provided between the first determination circuit 33 and the second determination circuit 34. That is, the time constant increasing circuit is configured with an RC filter.

[0060] FIG. 8 is a timing chart showing the input and output of the first determination circuit 33 according to the fourth embodiment. In FIG. 8 , the voltage indicating the first determination result represents the voltage input to the second determination circuit 34 via the time constant increasing circuit 35. The time constant increasing circuit 35 increases the time constant when the voltage indicating the first determination result output by the first determination circuit 33 is switched, thereby slowing the rise or fall of the signal indicating the voltage. The second determination circuit 34 determines that a high-level voltage has been input when the voltage indicating the first determination result exceeds a predetermined value (e.g., the average value of the low-level voltage and the high-level voltage), and determines that a low-level voltage has been input when the voltage indicating the applied state falls below the predetermined value. The time constant increasing circuit 35 increases the time constant of the signal indicating the voltage indicating the first determination result, thereby reducing the rate at which the voltage indicating the applied state and the voltage indicating the output state increase during the time between the application point and the output point due to the difference between the voltage indicating the applied state and the voltage indicating the output state. Before the voltage indicating the first determination result becomes higher than a predetermined value, the voltage indicating the application state and the voltage indicating the output state match, and the first determination circuit 33 outputs a low-level voltage, so that when the IPD 32 is not in a fault state, a high-level voltage is prevented from being input to the second determination circuit 34. Accordingly, when the IPD 32 is not in a fault state, the second determination circuit 34 is prevented from outputting a high-level voltage to the microcomputer 31.

[0061] According to the above configuration, when the IPD 32 is not in a faulty state, the control unit 311 of the microcomputer 31 is prevented from acquiring a high-level voltage as the second determination result from the second determination circuit 34. This makes it possible to prevent or reduce the possibility of the control unit 311 of the microcomputer 31 erroneously determining that any of the IPDs 32 is in a faulty state when there is no IPD 32 in a faulty state.

[0062] (Fifth Embodiment) When the control unit 311 of the microcomputer 31 according to the fifth embodiment determines, based on the acquired second determination result, that at least one IPD 32 is in a fault state, the control unit 311 acquires a current value corresponding to the power output downstream from the IPD 32, and determines whether each IPD 32 is in a fault state based on the state of voltage application to the IPD 32, the current value acquired from the IPD 32, and the input current value of the power supplied from the power supply device 1, thereby identifying the IPD 32 in a fault state. Differences between the fifth embodiment and the first embodiment will be described below. Except for the configuration described below, the fifth embodiment is identical to the first embodiment. Therefore, components identical to those in the first embodiment will be assigned the same reference numerals as those in the first embodiment, and descriptions thereof will be omitted.

[0063] FIG. 9 is a block diagram showing the main configuration of a power supply system S according to a fifth embodiment. The power supply system S is mounted on a vehicle M and includes a power supply device 1, an upstream device 2, an on-board device 3, and multiple loads 4. The power supply device 1 is a power supply that outputs direct current. The upstream device 2 may be an integrated ECU mounted on the vehicle M and is connected to the positive terminal of the power supply device 1 and the on-board device 3. The on-board device 3 is connected to the upstream device 2 and one end of the multiple loads 4. The negative terminal of the power supply device 1 and the other end of the load 4 are grounded. The upstream device 2 may be a front zone ECU mounted in the front zone of the vehicle M, and the on-board device 3 may be a left zone ECU mounted in the left zone or a right zone ECU mounted in the right zone of the vehicle M. In the following description, the power supply device 1 side of the current path from the power supply device 1 to the load 4 is referred to as the upstream side of the current, and the load 4 side is referred to as the downstream side of the current. Note that the first determination circuit 33 and the second determination circuit 34 are omitted from FIG. 9 .

[0064] The upstream device 2 includes a microcomputer 21 and an IPD (Intelligent Power Device) 22. Power supplied from the power supply device 1 is output downstream via the IPD 22 of the upstream device 2. The IPD 22 corresponds to an upstream switching device. The microcomputer 21 controls the output of power downstream of the IPD 22 and acquires the current value of the power output downstream by the IPD 22. The power output downstream via the IPD 22 is supplied to the in-vehicle device 3.

[0065] The in-vehicle device 3 includes a microcomputer 31 and a plurality of IPDs 32. Power supplied from the power supply device 1 to the in-vehicle device 3 via the IPD 22 of the upstream device 2 is distributed to the plurality of IPDs 32 and output to a downstream load 4 via each IPD 32. The IPDs 32 correspond to switching devices. The microcomputer 31 controls the output of power downstream of the IPDs 32 and acquires a current value corresponding to the power output downstream by the IPDs 32.

[0066] The microcomputer 21 of the upstream device 2 and the microcomputer 31 of the in-vehicle device 3 are connected by a communication bus B and can communicate using a communication protocol such as CAN (Control Area Network), CAN-FD, or Ethernet (registered trademark). The microcomputer 21 of the upstream device 2 transmits to the microcomputer 31 of the in-vehicle device 3 the current value of the power output by the IPD 22 downstream, i.e., the current value (input current value) of the power supplied to the in-vehicle device 3. The IPD 22 (upstream switching device) and the IPD 32 (switching device) may be provided in a single ECU. In this case, the IPD 22 (upstream switching device) and the IPD 32 (switching device) may be controlled by the same microcomputer. The microcomputer 31 of the individual ECU may control the output of power downstream of the IPD 22 of the upstream device 2 and may also acquire the current value of the power output downstream by the IPD 22.

[0067] FIG. 10 is a block diagram showing an example of a connection between a microcomputer 31 and an IPD 32 of an in-vehicle device 3 according to a fifth embodiment. FIG. 10 illustrates an example of a connection between one IPD 32 (IPD 32a) and the microcomputer 31, and the other IPDs 32 are not shown. The microcomputer 31 according to the fifth embodiment includes an in-vehicle communication unit 314. The in-vehicle communication unit 314 is an input / output interface using a communication protocol such as CAN, CAN-FD, or Ethernet (registered trademark). The control unit 311 communicates with the integrated ECU 2 or other in-vehicle devices via the in-vehicle communication unit 314. The in-vehicle communication unit 314 acquires, from the microcomputer 21 of the integrated ECU 2, the current value (input current value) of the power output downstream by the IPD 22 of the integrated ECU 2, i.e., the current value of the power supplied to the individual ECU 3.

[0068] The IPD 32 includes a power receiving terminal 321, a power output terminal 322, a voltage application terminal 323, and a current value detection terminal 324. A power line connecting the IPD 22 of the integrated ECU 2 and the IPD 32 of the individual ECU is connected to the power receiving terminal 321, and the power receiving terminal 321 receives power supplied from the upstream side.

[0069] The power output terminal 322 is connected to a power line that connects the IPD 32 and a load, and outputs the power received by the power receiving terminal 321 to the downstream load 4 .

[0070] The voltage application terminal 323 is connected to the input / output I / F 313 of the microcomputer 31 via a control line. In this embodiment, the voltage application terminal 323 is connected to PIN (1) of the input / output I / F 313. The power output from the power output terminal 322 is controlled based on the state of voltage applied from the microcomputer 31 to the voltage application terminal 323. Specifically, the IPD 32 includes, for example, an N-channel field effect transistor (FET). The drain of the FET is connected to the power receiving terminal 321, and the source is the power output terminal 322. The gate of the FET is connected to the voltage application terminal 323, and the voltage applied to the voltage application terminal 323 is applied to the gate of the FET. As a result, when a high-level voltage is applied to the voltage application terminal 323, the power received by the power receiving terminal 321 (power supplied to the IPD 32) is output from the power output terminal 322 to the downstream load 4 via the FET. When a low-level voltage is applied to the voltage application terminal 323, no power is output from the power output terminal 322 to the downstream load 4. The switching device (IPD 32) may be configured by a P-channel FET, a mechanical relay, or the like.

[0071] The current detection terminal 324 is connected to the input / output I / F 313 of the microcomputer 31 via a control line. In this embodiment, the current detection terminal 324 is connected to PIN (2) of the input / output I / F 313. The current detection terminal 324 outputs to the microcomputer 31 a current value corresponding to the power output from the power output terminal 322. Specifically, the IPD 32 includes, for example, a current detection circuit. The current detection circuit is connected between the source of the FET and the power output terminal 322. The current detection terminal 324 is also connected to the current detection circuit and outputs to the microcomputer 31 a current value obtained by multiplying the current value of the power output from the power output terminal 322, detected by the current detection circuit, by a predetermined coefficient. A pull-down resistor Rd is connected between the power output terminal 322 and the microcomputer 31. This allows the microcomputer 31 to obtain a voltage value proportional to the current value output from the current detection terminal 324. That is, the microcomputer 31 can acquire a voltage value that is proportional to the current value (output current value) of the power output from the power output terminal 322 of the IPD 32 .

[0072] As described above, each of the other IPDs 32 included in the individual ECU 3 also includes a power receiving terminal 321, a power output terminal 322, a voltage application terminal 323, and a current value detection terminal 324. In addition, each IPD 32 is connected to two pin terminals (PIN) of the microcomputer 31.

[0073] The first determination circuit 33 is connected to a control line connecting PIN (1) of the microcomputer 31 and the voltage application terminal 323 of the IPD 32 and to a power line connecting the power output terminal 322 of the IPD 32 and the load 4. The second determination circuit 34 is connected to the first determination circuit 33 and a pin terminal of the microcomputer 31. When the number of IPDs 32 is three, the second determination circuit 34 is connected to, for example, PIN (7) of the microcomputer 31, but the pin terminal to which the second determination circuit 34 is connected is not limited to this.

[0074] FIG. 11 is a flowchart showing the procedure of the failure determination process according to the fifth embodiment. The control unit 311 of the microcomputer 31 acquires a second determination result from the second determination circuit 34 (S11). Based on the acquired second determination result, the control unit 311 determines whether or not any IPD 32 is in a failed state (S12). Note that if the control unit 311 acquires a high-level voltage as the second determination result in S12, it determines that any IPD 32 is in a failed state. If the control unit 311 acquires a low-level voltage as the second determination result, it determines that no IPD 32 is in a failed state. If no IPD 32 is in a failed state (S12: NO), the control unit 311 returns the process to S11. If any IPD 32 is in a failed state (S12: YES), the control unit 311 identifies an IPD 32 to be subjected to failure determination (S13). Note that in S13, the control unit 311 sequentially identifies the IPDs 32a to 32c as targets for failure determination. That is, when S13 is executed for the first time, the IPD 32a is specified as the object to be determined for failure, and when S13 is executed for the second time after the process is returned, the IPD 32b is specified as the object to be determined for failure.

[0075] The control unit 311 acquires the state of voltage application to the IPD 32 (S14). The control unit 311 acquires the current value (output current value) of the power output from the power output terminal 322 of the IPD 32 from the IPD 32 that is the target of failure detection (S15). The control unit 311 also acquires the output current values ​​of other IPDs 32 that are not the target of failure detection (S16). The control unit 311 acquires the output current value of the IPD 32 by calculating it based on the voltage value acquired at the pin terminal connected to the current value detection terminal of the IPD 32 in S2 and S3. The control unit 311 acquires the input current value for the individual ECU 3 from the microcomputer 21 of the integrated ECU 2 (S17).

[0076] The control unit 311 of the microcomputer 31 determines whether the voltage applied to the IPD 32 being subjected to fault detection is a high-level voltage (S18). If the voltage applied to the IPD 32 is a high-level voltage (S18: YES), the control unit 311 determines whether the output current value of the IPD 32 being subjected to fault detection is equal to or greater than a predetermined threshold (S19). The threshold in S19 is the current value of the interruption characteristic with the minimum current value among the interruption characteristics for loads expected to be connected to the IPD 32. Note that the control unit 311 may also determine whether the IPD 32 is outputting a current, i.e., whether the output current value is greater than 0 A or 0 A. If the output current value of the IPD 32 being subjected to fault detection is equal to or greater than the predetermined threshold (S19: YES), the control unit 311 determines whether the input current value to the IPD 32 matches the sum of the output current values ​​of all the IPDs 32 included in the individual ECUs 3 (S20). If the sum of the input current value and the output current value matches (S20: YES), the control unit 311 determines that the IPD 32 being subjected to fault detection is in a normal state (S21). If the output current value of the IPD 32 being subjected to fault detection is not equal to or greater than a predetermined threshold (is less than the threshold) (S19: NO), or if the sum of the input current value and the output current value does not match (S20: NO), the control unit 311 determines that the IPD 32 being subjected to fault detection is in an open circuit fault state (S22). Note that if the control unit 311 determines that the IPD 32 is in an open circuit fault state, the control unit 311 may, for example, stop control of the IPD 32 determined to be in an open circuit fault state.

[0077] If the voltage applied to the IPD 32 is not a high-level voltage (i.e., a low-level voltage) (S18: NO), the control unit 311 determines whether the output current value of the IPD 32 being subjected to fault detection is equal to or greater than a predetermined threshold (S23). The threshold in S10 is the current value of the interruption characteristic with the minimum current value among the interruption characteristics for the loads expected to be connected to the IPD 32. Note that the control unit 311 may also determine whether the IPD 32 is outputting a current, i.e., whether the output current value is greater than 0 A or 0 A. If the output current value of the IPD 32 being subjected to fault detection is not equal to or greater than the predetermined threshold (i.e., less than the threshold) (S23: NO), the control unit 311 determines whether the input current value to the IPD 32 matches the sum of the output current values ​​of all the IPDs 32 included in the individual ECU 3 (S24). If the input current value and the sum of the output current values ​​match (S24: YES), the control unit 311 determines that the IPD 32 being subjected to fault detection is in a normal state (S25). If the output current value of the IPD 32 that is the failure determination target is equal to or greater than a predetermined threshold value (S23: YES), or if the sum of the input current value and the output current value does not match (S24: NO), the control unit 311 determines that the IPD 32 that is the failure determination target is in a short-circuit failure state (S26). Note that, if it is determined that the IPD 32 is in a short-circuit failure state, the control unit 311 may, for example, send a signal to the microcomputer 21 of the integrated ECU 2 to request that power supply to the individual ECUs 3 be stopped.

[0078] After determining the state of the IPD 32 in S21, S22, S25, or S26, the control unit 311 determines whether all IPDs 32 provided with first determination circuits 33 connected to the second determination circuit 34 that output the second determination result have been subject to failure determination (S27). If all IPDs 32 have not been subject to failure determination (S27: NO), the control unit 311 returns the process to S13, changes the IPD 32 subject to failure determination, and continues the failure determination process. If all IPDs 32 have been subject to failure determination (S27: YES), the control unit 311 ends the process. Note that the control unit 311 may store the state of the IPD 32 determined in S21, S22, S25, or S26 in a determination result table stored in the storage unit.

[0079] According to the above configuration and processing, the control unit 311 can identify an IPD 32 in a faulty state. While the determination of whether or not an IPD 32 is in a faulty state is periodically performed, the determination of whether or not each IPD 32 is in a faulty state is performed in an event-driven manner triggered by the determination of at least one IPD 32 being in a faulty state. The control unit 311 determines whether or not an IPD 32 is in a faulty state by simple processing based on the voltage indicating the second determination result. When it is determined that at least one IPD 32 is in a faulty state, the control unit 311 determines whether or not each IPD 32 is in a faulty state, thereby efficiently determining the fault state of the switching device (IPD 32). The storage unit 312 of the microcomputer 31 may store a table (fault determination table) that stores the state of the IPD 32 for conditions such as the voltage application state, the output current value of the IPD 32, and whether the sum of the input current value and the output current value matches. The control unit 311 may determine the state of the IPD 32 based on the fault determination table.

[0080] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The technical features described in each embodiment may be combined with one another, and the scope of the present invention is intended to include all modifications within the scope of the claims and equivalents thereto. Furthermore, independent and dependent claims described in the claims may be combined with one another in any and all combinations, regardless of the reference format. Furthermore, while the claims use a format in which a claim references two or more other claims (multiple claim format), this is not limiting. Multiple claims (multiple multiple claims) that reference at least one other claim may also be used.

[0081] REFERENCE SIGNS LIST 1 Power supply device 2 Upstream device 21 Microcomputer (microcomputer) 22 IPD 3 In-vehicle device 31 Microcomputer (microcomputer) 311 Control unit 312 Storage unit 313 Input / output I / F 314 In-vehicle communication unit 315 Internal bus 32 IPD 321 Power receiving terminal 322 Power output terminal 323 Voltage application terminal 324 Current value detection terminal 33 First determination circuit 34 Second determination circuit 35 Time constant increasing circuit 4 Load A Storage medium B Communication bus M Vehicle P Computer program S Power supply system

Claims

1. An on-vehicle device comprising: a plurality of opening / closing devices provided in parallel on a power line extending from a power supply device mounted on a vehicle; a control unit that applies a voltage to each of the opening / closing devices to control the output of power from each of the opening / closing devices to the downstream side in the direction of current flow from the power supply device; a first determination circuit that is provided in each of the opening / closing devices and outputs a first determination result indicating whether or not a state of voltage application by the control unit to the opening / closing device corresponds to a state of power output by the opening / closing device to the downstream side; and a second determination circuit that outputs a second determination result determining whether or not all of the first determination results output by each of the plurality of first determination circuits indicate a correspondence; wherein the control unit obtains the second determination result from the second determination circuit, and determines whether or not any of the plurality of opening / closing devices is in a faulty state based on the obtained second determination result.

2. The in-vehicle device according to claim 1, wherein the first determination circuit is connected to a control line connecting the control unit and the switching device, and to a power line connecting the switching device and a downstream load, and obtains the voltage application state from the control line, and obtains the power output state from the power line.

3. The in-vehicle device according to claim 1 or 2, wherein the first determination circuit: outputs a low-level voltage indicating that the voltage application state and the power output state correspond to each other if, when the control unit applies a high-level voltage to the opening / closing device, the voltage value of the power output by the opening / closing device to the downstream side is higher than a predetermined threshold, or when the control unit applies a low-level voltage to the opening / closing device, the voltage value of the power output by the opening / closing device to the downstream side is equal to or lower than a predetermined threshold; and outputs a high-level voltage indicating that the voltage application state and the power output state do not correspond to each other if, when the control unit applies a high-level voltage to the opening / closing device, the voltage value of the power output by the opening / closing device to the downstream side is equal to or lower than a predetermined threshold, or when the control unit applies a low-level voltage to the opening / closing device, the voltage value of the power output by the opening / closing device to the downstream side is higher than the predetermined threshold.

4. The in-vehicle device according to claim 3, wherein the second determination circuit acquires each of the voltages output by the plurality of first determination circuits, and outputs a low-level voltage to the control unit when all of the voltages acquired from the respective first determination circuits are low-level voltages, and outputs a high-level voltage to the control unit when at least one of the voltages acquired from the respective first determination circuits is a high-level voltage.

5. The in-vehicle device according to claim 4, wherein the control unit determines that at least one of the plurality of opening / closing devices is in a fault state when a high-level voltage is input from the second determination circuit.

6. The in-vehicle device according to claim 4, wherein the control unit acquires the voltage output by the second determination circuit at a predetermined period, and if the voltage acquired from the second determination circuit is a high-level voltage a predetermined number of times or more in succession, determines that at least one of the plurality of opening and closing devices is in a fault state.

7. The in-vehicle device according to claim 1 or 2, further comprising a time constant increasing circuit that increases the time constant of the input of the voltage application state to the first determination circuit.

8. The in-vehicle device according to claim 1 or 2, further comprising a time constant increasing circuit that increases the time constant of the output of the first judgment result from the first judgment circuit.

9. The in-vehicle device according to claim 1 or 2, wherein the first judgment circuit is constituted by an exclusive OR circuit, and the second judgment circuit is constituted by a logical OR circuit.

10. The in-vehicle device described in claim 1 or 2, wherein the control unit acquires the second judgment result, and judges whether or not at least one of the multiple opening / closing devices is in a faulty state based on the second judgment result, and if it is determined that at least one of the opening / closing devices is in a faulty state, acquires a current value corresponding to the power output from the opening / closing device to the downstream side, and judges whether or not the opening / closing device is in a faulty state based on the voltage application state to the opening / closing device, the current value acquired from the opening / closing device, and the input current value of the power supplied from the power supply device.

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