In-vehicle device, program, and information processing method

Abstract

An in-vehicle device that performs opening / closing control of an upstream opening / closing device provided on a power supply line from a power supply device installed in a vehicle, and is communicably connected to an in-vehicle ECU provided on the power supply line downstream of the upstream opening / closing device in the direction of the flow of current from the power supply device, the in-vehicle device comprising a control unit that controls the upstream opening / closing device, wherein the control unit determines whether a half-on failure has occurred in the upstream opening / closing device and, if it is determined that a half-on failure has occurred, outputs, to the in-vehicle ECU in stages, an instruction signal for suppressing power consumption.

Description

In-vehicle device, program, and information processing method

[0001] The present technology relates to an in-vehicle device, a program, and an information processing method. The present application claims priority based on Japanese Patent Application No. 2025-068384 filed on April 17, 2025, the entire content of which is incorporated herein by reference.

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

[0003] JP 2013-143905 A

[0004] An in-vehicle device according to an embodiment of the present disclosure performs opening / closing control of an upstream switching device provided on a power line from a power supply device mounted on a vehicle, and is communicably connected to an in-vehicle ECU provided on the power line on the downstream side of the upstream switching device in the flow direction of current from the power supply device, the in-vehicle device comprising a control unit that controls the upstream switching device, wherein the control unit determines whether a half-on failure has occurred in the upstream switching device, and when it is determined that the half-on failure has occurred, outputs an instruction signal for causing the in-vehicle ECU to reduce power consumption in a stepwise manner.

[0005] 1. A schematic diagram illustrating the configuration of an in-vehicle system including the in-vehicle device and the like according to the first embodiment. 2. A block diagram illustrating the internal configuration of the in-vehicle device and the like. 3. A flowchart illustrating processing of the control unit of the in-vehicle device. 4. An explanatory diagram (timing chart) for explaining the output timing of the instruction signal. 5. A block diagram illustrating the internal configuration of an in-vehicle device and the like according to the second embodiment. 6. A flowchart illustrating processing of the control unit of the in-vehicle device. 7. An explanatory diagram illustrating an example of a priority table. 8. An explanatory diagram (timing chart) for explaining the output timing of the instruction signal.

[0006] [Problems this disclosure aims to solve] The power supply control device described in Patent Document 1 does not take into consideration the fact that, when it is determined that a half-on failure has occurred, it outputs an instruction signal to the in-vehicle ECU to suppress power consumption.

[0007] This disclosure is made in view of the above circumstances and aims to provide an in-vehicle device, etc., that can output an instruction signal to the in-vehicle ECU to suppress power consumption when it is determined that a half-on failure has occurred.

[0008] [Effects of this Disclosure] According to one aspect of this disclosure, when it is determined that a half-on failure has occurred, it is possible to provide an in-vehicle device, etc., that outputs an instruction signal to the in-vehicle ECU to suppress power consumption.

[0009] [Description of Embodiments of the Disclosure] First, embodiments of the Disclosure will be listed and described. At least some of the embodiments described below may be combined in any way.

[0010] (1) An in-vehicle device according to one aspect of the present disclosure controls the opening and closing of an upstream switchgear provided on a power line from a power supply device mounted on a vehicle, and is communicated with an in-vehicle ECU provided on the power line downstream of the upstream switchgear in the direction of current flow from the power supply device, and includes a control unit for controlling the upstream switchgear, the control unit determines whether or not a half-on fault has occurred in the upstream switchgear, and if it determines that a half-on fault has occurred, outputs instruction signals to the in-vehicle ECU in stages to suppress power consumption.

[0011] In this embodiment, the on-board device is connected to a power line extending from a power supply unit mounted on the vehicle, and outputs power supplied from the power supply unit to an on-board ECU connected to the on-board device. The on-board device includes, for example, an upstream switchgear (upstream FET) composed of an FET, and the on-board ECU connected to the on-board device is connected to the power supply unit via the upstream switchgear. Furthermore, the on-board device and the on-board ECU are communicated with each other via an on-board network, for example, a CAN bus. Based on CAN frames received via the on-board network, the on-board device controls the opening and closing (on / off control) of the upstream switchgear, and supplies or cuts off power to the on-board ECU located on the power line downstream of the upstream switchgear in the direction of current flow from the power supply unit. The control unit of the on-board device continuously or periodically performs a detection process to detect the occurrence of a fault or abnormality in the upstream switchgear built into the on-board device, and determines whether a half-on fault has occurred based on the result of the fault detection process. When the control unit of the in-vehicle device determines that a half-on fault has occurred, it outputs instruction signals to the in-vehicle ECU in stages to suppress power consumption. As a result, when the in-vehicle ECU first receives the instruction signal from the in-vehicle device, it transitions from a normal mode that does not suppress power consumption to a low-power consumption mode that does suppress power consumption. Then, the in-vehicle ECU suppresses the power consumed by the in-vehicle ECU in stages according to the instruction signals it receives in stages. In other words, the control unit of the in-vehicle device controls the in-vehicle ECU to suppress or reduce power consumption in stages by outputting instruction signals to the in-vehicle ECU in stages. In this way, even if a half-on fault occurs in the upstream switchgear, the power consumption in the in-vehicle ECU can be suppressed in stages according to the instruction signals that are output in stages, that is, the current value flowing to the upstream switchgear can be suppressed in stages, thereby gradually reducing the Joule heat generated in the upstream switchgear and efficiently protecting the upstream switchgear.

[0012] (2) In an in-vehicle device according to one aspect of the present disclosure, the control unit acquires the voltage values ​​across the upstream switchgear, and determines that a half-on fault has occurred when the voltage values ​​across the upstream switchgear become equal to or greater than a predetermined threshold.

[0013] In this embodiment, the control unit of the in-vehicle device acquires the voltage value across the upstream switchgear. If the upstream switchgear is configured as, for example, an n-channel FET, the voltage across it is the potential difference between the drain and source (Vds), and is the value obtained by multiplying the current flowing through the upstream switchgear (FET) by the on-resistance of the upstream switchgear (FET). If the upstream switchgear is connected directly below a power supply unit that outputs a voltage of 12V as, for example, a high-side switch, the control unit of the in-vehicle device may acquire the voltage value at the source terminal of the upstream switchgear (FET) and obtain the voltage value across the upstream switchgear (Vds) by subtracting the voltage value at the source terminal from the output voltage value of the power supply unit (for example, 12V). When a half-on fault occurs, the on-resistance of the upstream switchgear (FET) tends to increase, which increases the voltage value across it (Vds) and decreases the voltage value at the source terminal. The on-board device's memory unit stores a threshold value, such as 1V, and the on-board device's control unit uses a voltage value obtained from a detection unit, such as a voltage sensor located directly below the source terminal of the upstream switchgear (FET), to determine whether the voltage across the upstream switchgear is equal to or greater than the threshold value by subtracting the obtained voltage value from the output voltage value of the power supply unit. The threshold value used to determine a half-on fault is not limited to a value based on the voltage across the terminals (Vds), but may also be set as a threshold obtained by subtracting the voltage drop that occurs when a half-on fault occurs from the output voltage value of the power supply unit (for example, 11V = 12V - 1V). In this case, the on-board device's control unit may determine that a half-on fault has occurred if the voltage value at the source terminal of the upstream switchgear (FET) falls below the threshold value (for example, 11V). In this way, by determining whether a half-on fault has occurred based on a comparison between the voltage across the terminals of the upstream switchgear (Vds), i.e., the voltage value at the source terminal of the upstream switchgear (FET), and a predetermined threshold value, the determination process can be performed with relatively simple calculations.

[0014] (3) An in-vehicle device according to one aspect of the present disclosure includes an in-vehicle ECU which includes a downstream switchgear connected to an in-vehicle load, the downstream switchgear connected in series with the upstream switchgear, and the instruction signal which includes a suppression instruction signal which suppresses the current flowing through the downstream switchgear to the in-vehicle ECU and a sleep instruction signal which causes the in-vehicle ECU to transition to a sleep state, and the control unit which, after determining that a half-on fault has occurred, outputs the suppression instruction signal and, if the voltage value across the upstream switchgear remains above a threshold, outputs the sleep instruction signal which causes the in-vehicle ECU to transition to a sleep state, and maintains the energized state to the in-vehicle ECU without outputting the sleep instruction signal when the voltage value across the upstream switchgear falls below a threshold.

[0015] In this embodiment, an in-vehicle load (actuator), such as a car air conditioner, lamps, or drive motor, is connected to the in-vehicle ECU, and this in-vehicle load is connected via a downstream switchgear (downstream FET) provided in the in-vehicle ECU. Therefore, in the direction of current flow from the power supply, the upstream switchgear (upstream FET) of the in-vehicle device, the downstream switchgear (downstream FET) of the in-vehicle ECU, and the in-vehicle load are connected in series in that order to the power supply, which is the upstreammost device. The in-vehicle ECU controls the switching (on / off control) or PWM control of the downstream switchgear (downstream FET) based on CAN frames received via the in-vehicle network, and controls the drive of the in-vehicle load connected to the downstream switchgear. When a half-on fault occurs, the control unit of the in-vehicle device outputs stepwise instruction signals, first outputting a suppression instruction signal, and then a sleep instruction signal. That is, the multiple instruction signals output in steps include at least a suppression instruction signal and a sleep instruction signal. Upon receiving a suppression instruction signal, the on-board ECU suppresses the current flowing through the downstream switchgear, i.e., the load current flowing to the on-board load via the downstream switchgear. In this case, the on-board ECU may also suppress the load current flowing to the on-board load by turning off (opening) the downstream switchgear and interrupting the current to the on-board load. The suppression instruction signal does not limit the case to turning off (opening) the downstream switchgear; if the downstream switchgear is PWM controlled, the ratio of the time the pulse is on in the duty cycle of the PWM signal may be reduced (for example, from 80% to 40%). In this case, the suppression instruction signal may also include a plurality of suppression instruction signals set in stages. For example, the first suppression instruction signal may reduce the duty cycle (from 100% to 50%), the second suppression instruction signal may reduce the duty cycle (from 50% to 25%), and the third suppression instruction signal may reduce the duty cycle to 0 (25% to 0%: off), that is, turn off (open) the downstream switchgear, thereby gradually suppressing (reducing) the current flowing to the downstream switchgear.In this case, each time such a stepwise suppression instruction signal is output, the control unit may determine whether the voltage value across the upstream switchgear remains above a threshold, and if the voltage value across the upstream switchgear falls below the threshold, it may maintain the power supply to the on-board ECU without outputting any further suppression instruction signals or sleep instruction signals. If the on-board device's control unit outputs a suppression instruction signal but the voltage value across the upstream switchgear remains above a threshold, it outputs a sleep instruction signal to transition the on-board ECU to a sleep state. As a result, the downstream switchgear is in an off (open) state, and the on-board ECU is in a sleep state. Current flows through the on-board device's upstream switchgear to the on-board ECU and the on-board load connected to the on-board ECU. When a half-on fault occurs, stepwise current suppression can be performed by first suppressing the current flowing to the on-board load (load), and then suppressing the current flowing to the on-board ECU. This makes it possible to suppress excessive heat generation in the upstream switchgear even when a half-on failure occurs, while effectively imposing operational restrictions on the on-board ECU and the on-board load connected to the on-board ECU.

[0016] (4) An in-vehicle device according to one aspect of the present disclosure includes an in-vehicle ECU which includes a plurality of downstream switchgears connected in parallel, each of the plurality of downstream switchgears which is connected to an in-vehicle load, and the instruction signal includes a suppression instruction signal which suppresses the current flowing through the downstream switchgears to the in-vehicle ECU and a sleep instruction signal which causes the in-vehicle ECU to transition to a sleep state, and the priority for driving the in-vehicle loads is predetermined, and when the control unit determines that a half-on fault has occurred, it outputs the suppression instruction signal to the downstream switchgear connected to the in-vehicle load with the lowest priority among the plurality of in-vehicle loads, and if the voltage value across the upstream switchgears remains above a threshold, it repeats the process of outputting the suppression instruction signal to the downstream switchgear connected to the in-vehicle load with the next lowest priority.

[0017] In this embodiment, the on-board ECU includes a plurality of downstream switchgears connected in parallel, and each of the plurality of downstream switchgears is connected to a respective on-board load. That is, the on-board ECU performs drive control for these plurality of on-board loads connected in parallel. In performing drive control for these plurality of on-board loads, each on-board load is assigned a predetermined priority according to its importance in vehicle control. When a half-on fault occurs, the control unit of the on-board device outputs a suppression instruction signal to the on-board ECU sequentially for the downstream switchgear connected to the on-board load with the lowest priority, thereby outputting the suppression instruction signal in stages. In response to the suppression instruction signal from the on-board device, the on-board ECU identifies the downstream switchgear that is the target of the suppression instruction signal and turns off the identified downstream switchgear, thereby interrupting the current flowing to the on-board load connected to that downstream switchgear. Each time a suppression instruction signal is output, the control unit of the on-board device determines whether the voltage value (Vds) across the upstream switchgear is above a threshold. If it is above the threshold, it repeats the process of outputting a suppression instruction signal to the downstream switchgear connected to the next lowest priority on-board load. By repeating this process, when the voltage value (Vds) across the upstream switchgear falls below the threshold, the downstream switchgear not targeted by the outputted suppression instruction signal can remain closed (on) without outputting any further suppression instruction signals. Therefore, the drive control of the on-board load connected to that downstream switchgear can continue. In this way, by targeting the suppression instruction signals to the downstream switchgear connected to the lowest priority on-board load in vehicle control, it is expected that even if a half-on failure occurs in the upstream switchgear, the drive control of the relatively higher priority on-board load can be continued. Note that the determination of priority for on-board loads is not limited to being performed by the on-board device, but may also be performed by the on-board ECU. In this case, the control unit of the in-vehicle device may output suppression instruction signals in stages without specifying the downstream switchgear, and the in-vehicle ECU may sequentially open (turn off) the downstream switchgear in order of decreasing priority each time it receives a suppression instruction signal from the in-vehicle device.

[0018] (5) In an in-vehicle device according to one aspect of the present disclosure, the priority of the in-vehicle load is determined based on the ASIL (Automotive Safety Integrity Level) defined for the application used to drive the in-vehicle load.

[0019] In this embodiment, each of the multiple in-vehicle loads connected to the in-vehicle ECU is driven and controlled by executing an application implemented in the in-vehicle ECU. That is, there is a correspondence between the in-vehicle loads connected to the in-vehicle ECU and the application implemented in the in-vehicle ECU. In this case, each application implemented in the in-vehicle ECU is assigned an ASIL (Automotive Safety Integrity Level) level related to the level of automotive safety. Specifically, each of these applications is assigned an ASIL level from D to A, and QM. Information regarding priority using ASIL is stored in a table format (priority table) in a storage area accessible by the control unit of the in-vehicle device, such as the storage unit of the in-vehicle device, and the control unit may output suppression instruction signals in stages by referring to the priority table. In this case, the priority table may include, as management items, a switch number that uniquely identifies the downstream switchgear, the number of the in-vehicle load connected to the downstream switchgear (load number), the state of the downstream switchgear (ON / OFF state), and a drive priority based on the ASIL level. Based on the driving priority of the vehicle load as defined in ASIL, a suppression instruction signal is output in stages to the downstream switchgear to which the vehicle load is connected, thereby gradually reducing the current (sum of load currents) flowing to the upstream switchgear while taking into account the level of vehicle safety.

[0020] (6) In an in-vehicle device according to one aspect of the present disclosure, the control unit outputs the sleep instruction signal if the voltage value across the upstream switch remains above a threshold value even when the suppression instruction signal has been output to all of the downstream switch devices.

[0021] In this embodiment, the control unit of the in-vehicle device outputs a suppression instruction signal to all downstream switchgears provided by the in-vehicle ECU. If the voltage value across the upstream switchgear remains above a threshold, the control unit outputs a sleep instruction signal to the in-vehicle ECU. Upon receiving the sleep instruction signal from the in-vehicle device, the in-vehicle ECU transitions from the normal state (wake-up state) that drives and controls the in-vehicle load to the sleep state, thereby cutting off power to all electronic circuits except those that are necessary. This reduces the power consumption of the in-vehicle ECU. As a result, the current flowing through the upstream switchgear is limited to the current necessary for the sleep-state in-vehicle ECU (dark current), keeping the voltage value across the upstream switchgear below the threshold and protecting the upstream switchgear from overheating.

[0022] (7) A program according to one aspect of the present disclosure controls the opening and closing of an upstream switchgear provided on a power line from a power supply unit mounted in a vehicle, and causes a computer, which is connected to an on-board ECU downstream of the upstream switchgear in the direction of current flow from the power supply unit, to execute processing, the program determines whether or not a half-on fault has occurred in the upstream switchgear, and if it is determined that a half-on fault has occurred, outputs instruction signals to the on-board ECU in stages to suppress power consumption.

[0023] In this embodiment, a program is provided that causes the computer to function as an in-vehicle device that outputs an instruction signal to the in-vehicle ECU to suppress power consumption when it determines that a half-on failure has occurred.

[0024] (8) An information processing method according to one aspect of the present disclosure is an information processing method that controls the opening and closing of an upstream switchgear provided on a power line from a power supply device mounted on a vehicle, and causes a computer that is communicably connected to an on-board ECU provided on the power line downstream of the upstream switchgear in the direction of current flow from the power supply device to perform processing, wherein the method determines whether or not a half-on fault has occurred in the upstream switchgear, and if it is determined that a half-on fault has occurred, outputs instruction signals to the on-board ECU in stages to suppress power consumption.

[0025] In this embodiment, an information processing method is provided that causes a computer to function as an in-vehicle device that outputs an instruction signal to the in-vehicle ECU to suppress power consumption when it determines that a half-on failure has occurred.

[0026] [Details of Embodiments of the Disclosure] The Disclosure will be described in detail based on the drawings illustrating its embodiments. An in-vehicle device 1 according to an embodiment of the Disclosure will be described below with reference to the drawings. However, the Disclosure is not limited to these examples and is intended to include all modifications within the meaning and scope of the claims, as indicated by the claims.

[0027] (Embodiment 1) Hereinafter, embodiments will be described based on the drawings. Figure 1 is a schematic diagram illustrating the configuration of an in-vehicle system S including an in-vehicle device 1 etc. according to Embodiment 1. Figure 2 is a block diagram illustrating the internal configuration of the in-vehicle device 1 etc. The in-vehicle system S consists of an in-vehicle device 1 mounted on a vehicle C, an in-vehicle ECU 2, and an in-vehicle network 3 that connects them in a communicative manner. The in-vehicle network 3 consists of a plurality of communication lines 31. When communication in the in-vehicle network 3 is performed according to a communication protocol such as CAN (Controller Area Network) or CAN-FD, the communication lines 31 correspond to a CAN bus.

[0028] Vehicle C is equipped with a power supply unit 4, which consists of a lead-acid battery, an alternator, or a secondary battery. The power supply unit 4 and the on-board device 1 are connected by a power line 41. The power supply unit 4 and the on-board device 1 are not limited to being directly connected by the power line 41; they may also be indirectly connected through an electrical box (junction box) such as a relay box or fuse box between the power supply unit 4 and the on-board device 1.

[0029] The in-vehicle device 1 and the in-vehicle ECU 2 are connected by a power line 41, and power from the power supply unit 4 is supplied to the in-vehicle ECU 2 via the in-vehicle device 1. The in-vehicle load 5 is connected to the in-vehicle ECU 2 via the power line 41. Therefore, in the direction of current flow from the power supply unit 4, the in-vehicle device 1, the in-vehicle ECU 2, and the in-vehicle load 5 are connected in series in this order to the power supply unit 4, which is the upstream device.

[0030] The in-vehicle device 1 includes, for example, an upstream switchgear 141 (upstream FET) composed of an n-channel FET, and the switching of the upstream switchgear 141 (upstream FET) is controlled by a microcomputer (μC) that constitutes the control unit 11 of the in-vehicle device 1. A power line 41 extending from the power supply unit 4 is connected to the upstream switchgear 141 (upstream FET) and is also branched upstream of the upstream switchgear 141, and the branched power line 41 is connected to the microcomputer (μC) of the in-vehicle device 1.

[0031] The vehicle-mounted ECU 2 includes, for example, a downstream switchgear 242 (downstream FET) composed of an n-channel FET, and the switching of the downstream switchgear 242 (downstream FET) is controlled by a microcomputer (μC) that constitutes the control unit 21 of the vehicle-mounted ECU 2. Power lines 41 extending from the power supply unit 4 via the vehicle-mounted device 1 are connected to the downstream switchgear 242 (downstream FET), and power lines 41 branched between the downstream switchgear 242 are connected to the microcomputer (μC) of the vehicle-mounted ECU 2.

[0032] Thus, the upstream switchgear 141 (upstream FET) of the in-vehicle device 1 functions as a high-side switch for the in-vehicle ECU 2 and in-vehicle load 5 connected to the downstream side. Therefore, in the direction of current flow from the power supply 4, the power supply 4, the upstream switchgear 141 (upstream FET) of the in-vehicle device 1, the downstream switchgear 242 (downstream FET) of the in-vehicle ECU 2, and the in-vehicle load 5 are connected in series in this order by the power line 41. The in-vehicle load 5 is grounded to a common ground such as the chassis of the vehicle C. Alternatively, the in-vehicle ECU 2 and the in-vehicle load 5 may be arranged upstream of the in-vehicle device 1 in the direction of current flow from the power supply 4, in which case the upstream switchgear 141 of the in-vehicle device 1 may function as a low-side switch.

[0033] Inside the in-vehicle device 1, a detection unit 142 is provided, which is connected to a power line 41 branched from the power line 41 between the output side (source terminal) of the upstream switchgear 141 (upstream FET) and the input side (drain terminal) of the downstream switchgear 242 (downstream FET). The detection unit 142 is composed of a voltage sensor equipped with a shunt resistor or the like, and detects the voltage value of the output side (source terminal) of the upstream switchgear 141 (upstream FET), and outputs the detected voltage value to the microcontroller (μC) of the in-vehicle device 1. Alternatively, the detection unit 142 may include a voltage divider circuit composed of two resistors connected in series, and an RC low-pass filter, and output the DC component voltage, which has been divided by the voltage divider circuit and passed through the RC low-pass filter, to the voltage detection terminal of the microcontroller (μC) of the in-vehicle device 1. The microcontroller (μC) of the in-vehicle device 1 may perform AD conversion on the voltage applied from the detection unit 142 via the voltage detection terminal and acquire the AD-converted voltage value periodically or continuously.

[0034] The vehicle load 5 is, for example, an actuator such as a car air conditioner, lamps, or drive motor. The vehicle load 5 is started or stopped by starting or cutting off power supply in accordance with the switching control (on / off control) of the downstream switchgear 242 (downstream FET) provided by the vehicle ECU 2.

[0035] The on-board device 1 functions as a power control device that controls the starting or stopping of the on-board ECU 2, and may be a device with relay functions such as a CAN gateway. Alternatively, the on-board device 1 may be an integrated ECU (vehicle computer) that comprehensively controls the entire vehicle C and has relay functions. In this case, the on-board ECU 2 may be individual ECUs controlled under the on-board device 1 (integrated ECU) and located in each area of ​​the vehicle C. Alternatively, the on-board device 1 may be configured as a body ECU that controls the body system actuators of the vehicle C. Alternatively, the on-board device 1 may be a PLB (Power LAN Box) that, in addition to relaying communications, also functions as a power distribution device that distributes and relays power output from a power supply device 4 such as a secondary battery and supplies power to on-board devices such as actuators. Various on-board equipment such as switches, sensors, or actuators may be connected to the on-board device 1.

[0036] The in-vehicle device 1 includes a control unit 11, a storage unit 12, a communication unit 13, and an input / output interface 14, and further comprises an upstream switchgear 141 (upstream FET) and a detection unit 142. The control unit 11 is composed of a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and performs various control and calculation processes by reading and executing a control program P (program product) and data pre-stored in the storage unit 12.

[0037] The storage unit 12 is composed of volatile memory elements such as RAM (Random Access Memory), non-volatile memory elements such as ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable ROM), or flash memory, or a combination of these storage devices, and stores in advance the control program P (program product) and data referenced during processing. The control program P (program product) stored in the storage unit 12 may be a control program P (program product) read from a recording medium M that the in-vehicle device 1 can read. Alternatively, the control program P (program product) may be downloaded from an external computer (not shown) connected to a communication network (not shown) and stored in the storage unit 12.

[0038] The communication unit 13 is an input / output interface using a communication protocol such as CAN, CAN-FD, or Ethernet (Ethernet / registered trademark), and the control unit 11 communicates with the in-vehicle ECU 2 connected to the in-vehicle network 3 via the communication unit 13. In the in-vehicle device 1, there may be multiple communication units 13.

[0039] The input / output interface 14 is, for example, a communication interface for serial communication. The input / output interface 14 includes multiple terminals (output terminals), and each terminal is connected to a signal line extending to the upstream switchgear 141 (upstream FET) and the detection unit 142, respectively. The signal lines are made up of, for example, a serial cable, a wire harness, or a conductive cable (direct wire) that transmits only one signal.

[0040] The upstream switchgear 141 is composed of a switching element such as an FET (Field Effect Transistor). Alternatively, the upstream switchgear 141 may be composed of an IPD (Intelligent Power Device). The detection unit 142 is composed of a voltage sensor or the like as described above.

[0041] The in-vehicle ECU 2 includes a control unit 21, a storage unit 22, a communication unit 23, and an input / output I / F 24, and further includes a downstream switching device 242 (downstream FET). The control unit 21, storage unit 22, communication unit 23 and input / output I / F 24 of this in-vehicle ECU 2 have the same configuration as the control unit 11, storage unit 12, communication unit 13 and input / output I / F 14 of the in-vehicle device 1.

[0042] The downstream switching device 242 (downstream FET) is connected to the input / output I / F 24 of the in-vehicle ECU 2 via a signal line. The downstream switching device 242 (downstream FET) may be configured by, for example, a switching element such as an FET (Field Effect Transistor), or an IPD (Intelligent Power Device). The in-vehicle load 5 is connected to the output side (source terminal) of the downstream switching device 242 (downstream FET) via a power supply line 41.

[0043] FIG. 3 is a flowchart illustrating the processing of the control unit of the in-vehicle device 1. The control unit 11 of the in-vehicle device 1 regularly performs the following processing when the vehicle C is stopped or started.

[0044] The control unit 11 of the in-vehicle device 1 turns on the upstream switching device 141 (S101). The control unit 11 of the in-vehicle device 1 turns on the upstream switching device 141 based on, for example, a CAN frame or the like received via the in-vehicle network 3. By turning on (closing) the upstream switching device 141, the voltage from the power supply device 4 is applied to the in-vehicle ECU 2 and the in-vehicle load 5 connected to the downstream side of the upstream switching device 141.

[0045] The control unit 21 of the in-vehicle ECU 2 is driven (transitions to a wake-up state) by being brought into an energized state with the power supply device 4 via the upstream switching device 141, and executes the application stored in the storage unit 22 of the in-vehicle ECU 2, thereby performing opening / closing control (on / off control) of the downstream switching device 242, and starting drive control of the in-vehicle load 5 connected to the downstream switching device 242.

[0046] The control unit 11 of the in-vehicle device 1 determines whether the voltage value across the upstream switchgear 141 is above a threshold (S102). A detection unit 142, such as a voltage sensor, is arranged on the output side (source terminal) of the upstream switchgear 141, and the control unit 11 of the in-vehicle device 1 periodically or continuously acquires the voltage value (source terminal voltage value) detected by the detection unit 142. Alternatively, a power line 41 (branched power line) branched from the power line 41 on the output side of the upstream switchgear 141 is connected to the voltage detection terminal of a microcomputer (microcontroller: μC) that constitutes the control unit 11 of the in-vehicle device 1, and the microcontroller periodically or continuously acquires the voltage value (source terminal voltage value) applied via the branched power line. In this case, the branched power line may have a detection unit 142, which is composed of a voltage divider circuit consisting of two resistors connected in series and an RC low-pass filter. The branch power line on which the detection unit 142 is located is connected to the voltage detection terminal of the microcontroller that constitutes the control unit 11 of the in-vehicle device 1. As a result, the DC component voltage, which has been divided by the voltage divider circuit and passed through the RC low-pass filter, is input to the voltage detection terminal of the microcontroller.

[0047] The control unit 11 of the in-vehicle device 1 may periodically acquire voltage values ​​(voltage values ​​at the source terminal of the upstream switchgear 141 (upstream FET)) via the detection unit 142, and store the acquired voltage values ​​in the storage unit 12 of the in-vehicle device 1, associated with the time of acquisition. The control unit 11 of the in-vehicle device 1 calculates the voltage across both ends of the upstream switchgear 141 (upstream FET), i.e., the potential difference between the drain and source (Vds: drain-source voltage value), by subtracting the voltage values ​​acquired via the detection unit 142 from the output voltage value from the power supply device 4 (for example, 12V).

[0048] The control unit 11 of the in-vehicle device 1 determines whether the voltage (Vds) across the upstream switching device 141 is equal to or higher than a threshold (for example, 1V) pre-stored in the storage unit 12 of the in-vehicle device 1 (threshold ≤ Vds). The on-resistance of an N-channel FET is generally 1mΩ or less, and at this time, the voltage (Vds) across the upstream switching device 141 is a relatively small value such as 0.012V. In contrast, when the voltage (Vds) across the two terminals is equal to or higher than the threshold set at, for example, 1V, it is assumed that the resistance value of the on-resistance has increased due to the occurrence of a half-on fault.

[0049] When the voltage value across the two terminals is not equal to or higher than the threshold (S102: NO), that is, when the voltage value across the two terminals is less than the threshold, the control unit 11 of the in-vehicle device 1 determines that no half-on fault has occurred (S1021). The control unit 11 of the in-vehicle device 1 performs loop processing to execute S102 again, thereby continuing the process of monitoring the voltage value across the upstream switching device 141, that is, the process of determining whether a half-on fault has occurred, and maintains the control mode in the normal mode. At this time, the control unit 21 of the in-vehicle ECU 2 performs switching control of the downstream switching device 242 (downstream FET) in the normal mode without suppressing power consumption, and continues drive control for the in-vehicle load 5.

[0050] When the voltage value across the two terminals is equal to or higher than the threshold (S102: YES), the control unit 11 of the in-vehicle device 1 determines that a half-on fault has occurred (S103). When the voltage value across the two terminals is equal to or higher than the threshold, the control unit 11 of the in-vehicle device 1 determines that a half-on fault has occurred in the upstream switching device 141 (upstream FET), and it is assumed that the resistance value of the on-resistance has increased due to the half-on fault. Alternatively, the control unit 11 of the in-vehicle device 1 may determine that a half-on fault has occurred when the voltage value across the two terminals is equal to or higher than the threshold, and a value (Vds×I) obtained by multiplying the voltage value (Vds) across the two terminals by the current value (I) flowing through the upstream switching device 141 is equal to or higher than a predetermined allowable value. At this time, the multiplied value (Vds×I) is used for heat generation calculation in the upstream switching device 141, and the current value (I) flowing through the upstream switching device 141 may be a predetermined fixed value.

[0051] The control unit 11 of the in-vehicle device 1 outputs a suppression instruction signal to the in-vehicle ECU 2 (S104). The control unit 11 of the in-vehicle device 1 outputs a suppression instruction signal to the in-vehicle ECU 2 when it determines that a half-on fault has occurred in the upstream switchgear 141 (upstream FET). In this case, the control unit 11 of the in-vehicle device 1 is not limited to immediately outputting a suppression instruction signal to the in-vehicle ECU 2 when it determines that the half-on fault has occurred, but may also output a suppression instruction signal if the half-on fault continues after a predetermined period of time has elapsed. That is, the control unit 11 of the in-vehicle device 1 may also acquire voltage values ​​from the detection unit 142 multiple times after the half-on fault has occurred, and output a suppression instruction signal if the half-on fault continues after a predetermined period of time has elapsed. Alternatively, when the control unit 11 of the in-vehicle device 1 makes a provisional determination that a half-on fault has occurred based on a single voltage value obtained from the detection unit 142, it may make a final determination of whether or not a half-on fault has occurred by comparing the average, median, or mode of voltage values ​​obtained multiple times from the detection unit 142 over a predetermined period from the time of the provisional determination with a threshold value.

[0052] The suppression instruction signal may be an instruction signal to the on-board ECU 2 to turn off (open) the downstream switchgear 242 (downstream FET) provided in the on-board ECU 2. The control unit 21 of the on-board ECU 2 acquires (receives) the suppression instruction signal from the on-board device 1 and transitions from a normal mode in which power consumption is not suppressed to a low-power consumption mode in which power consumption is suppressed. Then, in response to the acquired suppression instruction signal, the control unit 21 of the on-board ECU 2 executes a process (load current suppression process) to suppress the current flowing through the downstream switchgear 242 (downstream FET) provided in the on-board ECU 2, that is, the load current flowing to the on-board load 5 via the downstream switchgear 242. When executing the load current suppression process, the control unit 21 of the on-board ECU 2 may also suppress the load current flowing to the on-board load 5 by turning off (opening) the downstream switchgear 242 and interrupting the current to the on-board load 5.

[0053] In this embodiment, the control unit 11 of the in-vehicle device 1 outputs an instruction signal to turn off (open) the downstream switchgear 242 (downstream FET) provided by the in-vehicle ECU 2 as a suppression instruction signal, but is not limited to this. When the control unit 21 of the in-vehicle ECU 2 performs PWM control on the downstream switchgear 242, the suppression instruction signal from the in-vehicle device 1 may be an instruction signal that reduces the ratio of the time the pulse is on in the duty cycle of the PWM signal. In this case, the suppression instruction signal may include a plurality of suppression instruction signals set in stages (first suppression instruction signal, second suppression instruction signal, nth suppression instruction signal), for example, the duty cycle may be reduced by the first suppression instruction signal (from 100% to 50%), the duty cycle may be reduced by the second suppression instruction signal (from 50% to 25%), and finally the duty cycle may be reduced to 0 (25% to 0%: off) by the third suppression instruction signal, that is, the current flowing to the downstream switchgear 242 may be reduced in stages.

[0054] The control unit 21 of the in-vehicle ECU 2 may output a plurality of suppression instruction signals (first suppression instruction signal, second suppression instruction signal, nth suppression instruction signal) in a stepwise manner, and each time, it may repeatedly determine whether the voltage value across both ends is above a threshold, similar to the process in S102, and if it is above the threshold, it may output the next suppression instruction signal. In this case, the control unit 21 of the in-vehicle ECU 2 may output all of the plurality of suppression instruction signals in a stepwise manner, that is, it may output a suppression instruction signal to turn off (open) the downstream switchgear 242, and then execute the process in S105.

[0055] The control unit 11 of the in-vehicle device 1 determines whether the voltage value across the upstream switchgear 141 is above a threshold (S105). The control unit 21 of the in-vehicle ECU 2 determines whether the voltage value across the upstream switchgear 141 is above a threshold, similar to the process in S102.

[0056] If the voltage value across both ends is above the threshold (S105: YES), that is, if the state in which the voltage value across both ends is above the threshold is maintained, the control unit 11 of the in-vehicle device 1 outputs a sleep instruction signal to the in-vehicle ECU 2 (S106). If the voltage value across both ends is above the threshold, that is, if a suppression instruction signal is output and the downstream switchgear 242 (downstream FET) is turned off (open) to interrupt the load current flowing to the in-vehicle load 5, but the state in which the voltage value across both ends is above the threshold is maintained, the control unit 11 of the in-vehicle device 1 outputs a sleep instruction signal to the in-vehicle ECU 2. The control unit 21 of the in-vehicle ECU 2 transitions from the wake-up state to the sleep state upon receiving the sleep instruction signal from the in-vehicle device 1. The control unit 21 of the in-vehicle ECU 2, having transitioned to the sleep state, performs the process of turning off the power to all electronic circuits except those that are necessary, thereby reducing the power consumption of the in-vehicle ECU 2 to a minimum.

[0057] After outputting a sleep instruction signal (S106), or when the voltage value across both ends is not above a threshold (S105: NO), i.e., when the voltage value across both ends falls below a certain threshold, the control unit 11 of the in-vehicle device 1 maintains the power supply state to the in-vehicle ECU 2. At this time, the in-vehicle ECU 2 maintains a low power consumption mode.

[0058] Figure 4 is an explanatory diagram (timing chart) illustrating the output timing of the instruction signal. This diagram (timing chart) illustrates the transition from normal mode to low-power mode in the in-vehicle ECU 2 and the displacement of the voltage (Vds) across the upstream switchgear 141. In this timing chart, the horizontal axis represents elapsed time, and on the vertical axis, the upper section represents the transition of the in-vehicle ECU 2 to low-power mode (from OFF to ON), and the lower section represents the displacement of the voltage (Vds) across the switchgear.

[0059] When a half-on fault occurs in the upstream switchgear 141 (upstream FET), the voltage across the upstream switchgear 141 (Vds) increases from a normal value such as 0.012V to an abnormal value (e.g., 5V) that exceeds a threshold (Vds threshold) set at 1V. When the control unit 11 of the in-vehicle device 1 receives such an abnormal voltage across the switchgear (Vds) from the detection unit 142, it outputs a suppression instruction signal (first instruction signal) to the in-vehicle ECU 2, causing the downstream switchgear 242 (downstream FET: SW-1) to turn off (open). Upon receiving the suppression instruction signal (first instruction signal), the control unit 21 of the in-vehicle ECU 2 transitions from a normal mode, which drives and controls the in-vehicle load 5 without suppressing power consumption, to a low-power consumption mode (low-power consumption mode ON) that suppresses power consumption.

[0060] As a result, the voltage across the upstream switchgear 141 where a half-on fault has occurred (Vds) decreases, but it is expected that the decreased voltage across the switchgear (Vds threshold) will remain above a threshold. At this time, the control unit 11 of the in-vehicle device 1 further outputs a sleep instruction signal (next instruction signal) to the in-vehicle ECU 2, causing the in-vehicle ECU 2 to transition from the wake-up state to the sleep state. The in-vehicle ECU 2 receives the sleep instruction signal (next instruction signal) and transitions to the sleep state with the downstream switchgear 242 (downstream FET: SW-1) turned off (open) in response to the suppression instruction signal (first instruction signal). Only a relatively small dark current flows through the in-vehicle ECU 2 once it has transitioned to the sleep state, which allows the voltage across the upstream switchgear 141 (Vds) to remain below the threshold, thus protecting the upstream switchgear 141 from overheating. In this case, power is continuously supplied to the vehicle ECU 2 via the upstream switchgear 141 (upstream FET), and the vehicle ECU 2 maintains a low power consumption mode.

[0061] These suppression instruction signals and sleep instruction signals correspond to or are classified as instruction signals for the in-vehicle ECU 2 to suppress power consumption. In other words, the control unit 11 of the in-vehicle device 1 outputs instruction signals to the in-vehicle ECU 2 to suppress power consumption in stages. The instruction signals output in stages (suppression instruction signals, sleep instruction signals) cause the in-vehicle ECU 2 to suppress power consumption in stages. In other words, the amount of power consumption suppression by the first instruction signal (suppression instruction signal) is less than the amount of power consumption suppression by the next instruction signal (sleep instruction signal). These multiple instruction signals output in stages may be defined in the in-vehicle device 1 and the in-vehicle ECU 2 in such a way.

[0062] (Embodiment 2) Figure 5 is a block diagram illustrating the internal configuration of the in-vehicle device 1, etc., according to Embodiment 2. The in-vehicle system S according to Embodiment 2 is composed of the in-vehicle device 1 and the in-vehicle ECU 2, similar to Embodiment 1. In this case, the block diagram illustrating the internal configuration (hardware configuration) of the in-vehicle device 1 is the same as that of Embodiment 1.

[0063] The in-vehicle ECU 2 is equipped with multiple (five in this embodiment) downstream switchgears 242 (downstream FETs), and each of these downstream switchgears 242 is connected to each of the in-vehicle loads 5. Inside the in-vehicle ECU 2, the power line 41 extending from the in-vehicle device 1 is branched into multiple lines, and each of the branched power lines 41 is connected to a downstream switchgear 242 (downstream FET), thereby forming a parallel circuit in which these downstream switchgears 242 (downstream FETs) are connected in parallel. Therefore, multiple (five in this embodiment) in-vehicle loads 5 are connected to the in-vehicle ECU 2, and a parallel circuit is formed in which these in-vehicle loads 5 are connected in parallel.

[0064] The control unit 21 (μC) of the in-vehicle ECU 2 individually controls the opening and closing of these downstream switchgears 242 (downstream FETs), thereby individually driving the in-vehicle loads 5 connected to the downstream switchgears 242. The memory unit 22 of the in-vehicle ECU 2 stores applications used when driving each of these in-vehicle loads 5, and the control unit 21 of the in-vehicle ECU 2 may execute an application to drive the corresponding in-vehicle load 5, that is, to control the opening and closing of the downstream switchgears 242 (downstream FETs) to which the in-vehicle load 5 is connected. As will be described in detail later, the application corresponding to each of the multiple in-vehicle loads 5 may have an ASIL (Automotive Safety Integrity Level) level related to the level of automotive safety set.

[0065] Figure 6 is a flowchart illustrating the processing of the control unit of the in-vehicle device 1. The control unit 11 of the in-vehicle device 1 routinely performs the following processing when the vehicle C is stopped or started.

[0066] The control unit 11 of the on-board device 1 turns on the upstream switchgear 141 (S201). The control unit 11 of the on-board device 1 determines whether the voltage value across the upstream switchgear 141 is equal to or greater than a threshold (S202). If the voltage value across the ends is not equal to or greater than the threshold (S202: NO), that is, if the voltage value across the ends is less than a threshold, the control unit 11 of the on-board device 1 determines that a half-on fault has not occurred (S2021). If the voltage value across the ends is equal to or greater than the threshold (S202: YES), the control unit 11 of the on-board device 1 determines that a half-on fault has occurred (S203). The control unit 11 of the on-board device 1 performs the processing from S201 to S203 and S2021 in the same manner as the processing S101 to S103 and S1021 of Embodiment 1.

[0067] The control unit 11 of the in-vehicle device 1 outputs a suppression instruction signal to the in-vehicle ECU 2 based on priority (S204). When the control unit 11 of the in-vehicle device 1 determines that a half-on fault has occurred in the upstream switchgear 141 (upstream FET), it outputs a suppression instruction signal to the in-vehicle ECU 2. At this time, immediately after determining that a half-on fault has occurred, the control unit 11 of the in-vehicle device 1 outputs a suppression instruction signal to the in-vehicle ECU 2 to turn off (open) the downstream switchgear 242 (downstream FET) to which the in-vehicle load 5 with the lowest drive priority (drive priority) is connected. In outputting a suppression instruction signal according to the drive priority in this way, the control unit 11 of the in-vehicle device 1 may refer to a priority table stored in the storage unit 12 of the in-vehicle device 1.

[0068] Figure 7 is an explanatory diagram illustrating a priority table. The priority table defines information regarding priority (drive priority) using ASIL (Automotive Safety Integrity Level) in a table format, and the management items include switch number, load number, status, drive priority, and ASIL.

[0069] The switch number management item stores the switch number (SW-1, SW-2, SW-3, SW-4, SW-5) that uniquely identifies the downstream switchgear 242. The load number management item stores the numbers (L-1, L-2, L-3, L-4, L-5) of the on-board load 5 connected to the downstream switchgear 242.

[0070] The status management item stores the status (ON / OFF state) of the downstream switchgear 242. The value stored in the status management item is updated from ON to OFF each time a suppression instruction signal is output to the downstream switchgear 242 by the control unit 11 of the on-board device 1.

[0071] The drive priority management item stores the drive priority based on the ASIL level. In this embodiment, the downstream switchgear 242 is turned off (opened) in order of decreasing drive priority. That is, the lower the drive priority, the earlier it is turned off (the higher the off priority). The ASIL management item stores the ASIL level set for the application that controls the on-board load 5 connected to the downstream switchgear 242. The ASIL level (automobile safety level) ranges from QM being the lowest to D being the highest.

[0072] The control unit 11 of the on-board device 1 determines whether the voltage value across the upstream switchgear 141 is above a threshold (S205). The control unit 11 of the on-board device 1 determines whether the voltage value across the upstream switchgear 141 is above a threshold, similar to process S202 (S102).

[0073] If the voltage value across both ends is above the threshold (S205: YES), that is, if the state in which the voltage value across both ends is above the threshold is maintained, the control unit 11 of the in-vehicle device 1 determines whether or not it has output a suppression instruction signal to all downstream switchgears 242 (S206). When multiple downstream switchgears 242 (downstream FETs) and an in-vehicle load 5 are connected to the in-vehicle ECU 2, it is assumed that even if any of the downstream switchgears 242 are turned off (open), the state in which the voltage value across both ends (Vds) of the upstream switchgear 141 (upstream FET) remains above the threshold will continue.

[0074] The control unit 11 of the in-vehicle device 1 outputs suppression instruction signals to a plurality of downstream switchgears 242 in stages based on the drive priority of the in-vehicle load 5 connected to the downstream switchgears 242, causing the in-vehicle ECU 2 to execute control to turn off (open) these downstream switchgears 242 in stages. Therefore, it is assumed that in a plurality of downstream switchgears 242 (downstream FETs), a state in which only some of the downstream switchgears 242 are turned off (open) is assumed, and the control unit 11 of the in-vehicle device 1 determines whether or not it has output suppression instruction signals to all of the downstream switchgears 242. In this case, the control unit 11 of the in-vehicle device 1 may determine whether or not it has output suppression instruction signals to all of the downstream switchgears 242 by referring to a priority table.

[0075] If no suppression instruction signals have been output to all downstream switchgears 242 (S206: NO), the control unit 11 of the on-board device 1 performs loop processing to execute the process from S204 again. At this time, the control unit 11 of the on-board device 1 generates a suppression instruction signal for the downstream switchgear 242 that was targeted by the suppression instruction signal output last time, targeting the downstream switchgear 242 with the next highest drive priority, and outputs the generated suppression instruction signal to the on-board ECU 2. By referring to the priority table, the control unit 11 of the on-board device 1 can efficiently identify the downstream switchgear 242 that is currently ON and has the lowest drive priority. By repeating the process from S204 again in this way, the downstream switchgears 242 to which the on-board load 5 is connected can be turned OFF (opened) in stages, in order of the lowest drive priority of the on-board load 5.

[0076] If a suppression instruction signal is output to all downstream switchgears 242 (S206: YES), the control unit 11 of the on-board device 1 outputs a sleep instruction signal to the on-board ECU 2 (S207). When a suppression instruction signal is output to all downstream switchgears 242, the load current flowing to all on-board loads 5 connected to the on-board ECU 2 is interrupted. If, despite the load current flowing to all on-board loads 5 being interrupted in this way, the voltage value across both ends remains above a threshold, the control unit 11 of the on-board device 1 outputs a sleep instruction signal to the on-board ECU 2. The control unit 11 of the on-board device 1 performs the process in S207 in the same way as the process in S106 of Embodiment 1.

[0077] After outputting a sleep instruction signal (S207), or when the voltage value across both ends is not above a threshold (S205: NO), i.e., when the voltage value across both ends falls below a certain threshold, the control unit 11 of the in-vehicle device 1 maintains the power supply state to the in-vehicle ECU 2. At this time, the in-vehicle ECU 2 maintains a low power consumption mode.

[0078] Figure 8 is an explanatory diagram (timing chart) illustrating the output timing of the instruction signal. This explanatory diagram (timing chart) illustrates the transition from normal mode to low-power mode in the in-vehicle ECU 2 and the displacement of the voltage (Vds) across the upstream switchgear 141. In this timing chart, the horizontal axis represents elapsed time, and on the vertical axis, the upper section represents the transition of the in-vehicle ECU 2 to low-power mode (from OFF to ON), and the lower section represents the displacement of the voltage (Vds) across the switchgear.

[0079] When a half-on fault occurs in the upstream switchgear 141 (upstream FET), the voltage across the upstream switchgear 141 (Vds) increases from a normal value such as 0.012V to an abnormal value (e.g., 5V) that exceeds a threshold (Vds threshold) set at 1V. When the control unit 11 of the in-vehicle device 1 receives such an abnormal voltage across the ends (Vds) from the detection unit 142, it outputs a suppression instruction signal (initial instruction signal) to the in-vehicle ECU 2, causing the downstream switchgear 242 (downstream FET: SW-1), which has the lowest drive priority, to turn off (open). As a result, the voltage across the ends (Vds) of the upstream switchgear 141 where the half-on fault occurred decreases, but it is expected that the decreased voltage across the ends (Vds) will continue to be above the threshold (Vds threshold).

[0080] In response, the control unit 11 of the in-vehicle device 1 outputs a suppression instruction signal (second instruction signal) to the in-vehicle ECU 2, causing the downstream switchgear 242 (downstream FET: SW-2), which has the second lowest drive priority, to be turned off (open). The output of this suppression instruction signal (second instruction signal) will further decrease the voltage (Vds) across the upstream switchgear 141 where the half-on fault occurred, but it is expected that the reduced voltage (Vds) across the switchgear will remain above the threshold (Vds threshold).

[0081] In response, the control unit 11 of the in-vehicle device 1 outputs a suppression instruction signal (third instruction signal) to the in-vehicle ECU 2, causing the downstream switchgear 242 (downstream FET: SW-3), which has the third lowest drive priority, to be turned off (open). The output of this suppression instruction signal (third instruction signal) will further decrease the voltage (Vds) across the upstream switchgear 141 where the half-on fault occurred, but it is expected that the reduced voltage (Vds) across the switchgear will remain above the threshold (Vds threshold).

[0082] In response, the control unit 11 of the in-vehicle device 1 outputs a suppression instruction signal (the fourth instruction signal) to the in-vehicle ECU 2, causing the downstream switchgear 242 (downstream FET: SW-4), which has the fourth lowest drive priority, to be turned off (open). The output of this suppression instruction signal (the fourth instruction signal) will further decrease the voltage (Vds) across the upstream switchgear 141 where the half-on failure occurred, but it is expected that the reduced voltage (Vds) across the switchgear will remain above the threshold (Vds threshold).

[0083] In this manner, the control unit 11 of the in-vehicle device 1 outputs suppression instruction signals (the 1st to the nth instruction signals) in stages according to the drive priority. The in-vehicle ECU 2 performs a gradual power consumption suppression process by maintaining the off (open) state of the downstream switchgear 242 corresponding to the previous suppression instruction signal, and then turning off (opening) the downstream switchgear 242 with the next drive priority corresponding to the current suppression instruction signal. Even when all downstream switchgear 242 (downstream FETs: SW-1 to SW-n) are ultimately turned off (open), it is assumed that the voltage across them (Vds) will continue to be above a threshold (Vds threshold). At this point, the control unit 11 of the in-vehicle device 1 further outputs a sleep instruction signal (the final instruction signal) to the in-vehicle ECU 2, causing the in-vehicle ECU 2 to transition from the wake-up state to the sleep state. When the in-vehicle ECU 2 transitions to sleep mode, only a relatively small dark current flows through it. This allows the voltage across the upstream switchgear 141 (Vds) to remain below a threshold, protecting the upstream switchgear 141 from overheating. In this state, power to the in-vehicle ECU 2 via the upstream switchgear 141 (upstream FET) continues, and the in-vehicle ECU 2 maintains a low-power mode.

[0084] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims and not in the sense described above, and all modifications within the sense and scope equivalent to the claims are intended to be included.

[0085] With respect to the multiple claims described in the claims, they may be combined with each other regardless of the form of reference. Multiple dependent claims that depend on multiple claims may be described in the claims. Multiple dependent claims that depend on multiple dependent claims may be described. Even if multiple dependent claims that depend on multiple dependent claims are not described, this does not limit the description of multiple dependent claims that depend on multiple dependent claims.

[0086] C Vehicle S In-vehicle system 1 In-vehicle device 11 Control unit 12 Memory unit M Recording medium P Control program (program product) 13 Communication unit 14 Input / output I / F 141 Upstream switchgear (upstream FET) 142 Detection unit 2 In-vehicle ECU 21 Control unit 22 Memory unit 23 Communication unit 24 Input / output I / F 242 Downstream switchgear (downstream FET) 3 In-vehicle network 31 Communication line 4 Power supply unit 41 Power line 5 In-vehicle load

Claims

1. An in-vehicle device that controls the opening and closing of an upstream switchgear provided on a power line from a power supply unit mounted on a vehicle, and is communicated with an in-vehicle ECU provided on the power line downstream of the upstream switchgear in the direction of current flow from the power supply unit, comprising a control unit for controlling the upstream switchgear, the control unit determines whether or not a half-on fault has occurred in the upstream switchgear, and if it determines that a half-on fault has occurred, outputs a stepwise instruction signal to the in-vehicle ECU to suppress power consumption.

2. The in-vehicle device according to claim 1, wherein the control unit acquires the voltage values ​​across the upstream switchgear, and determines that a half-on fault has occurred when the voltage values ​​across the upstream switchgear exceed a predetermined threshold.

3. The in-vehicle ECU includes a downstream switchgear connected to an in-vehicle load, the downstream switchgear is connected in series with the upstream switchgear, the instruction signal includes a suppression instruction signal that suppresses the current flowing through the downstream switchgear to the in-vehicle ECU, and a sleep instruction signal that causes the in-vehicle ECU to transition to a sleep state, the control unit outputs the suppression instruction signal after determining that a half-on fault has occurred, and if the voltage value across the upstream switchgear remains above a threshold, outputs the sleep instruction signal to cause the in-vehicle ECU to transition to a sleep state, and maintains the power supply state to the in-vehicle ECU without outputting the sleep instruction signal when the voltage value across the upstream switchgear falls below a threshold.

4. The in-vehicle ECU includes a plurality of downstream switchgears connected in parallel, each of the plurality of downstream switchgears is connected to an in-vehicle load, the instruction signal includes a suppression instruction signal to the in-vehicle ECU to suppress the current flowing through the downstream switchgears and a sleep instruction signal to cause the in-vehicle ECU to transition to a sleep state, the priority for driving the in-vehicle loads is predetermined, and the control unit, when it determines that a half-on fault has occurred, outputs the suppression instruction signal to the downstream switchgear connected to the in-vehicle load with the lowest priority among the plurality of in-vehicle loads, and if the voltage value across the upstream switchgear remains above a threshold, the control unit repeats the process of outputting the suppression instruction signal to the downstream switchgear connected to the in-vehicle load with the next lowest priority.

5. The in-vehicle device according to claim 4, wherein the priority of the in-vehicle load is determined based on the ASIL (Automotive Safety Integrity Level) defined for the application used to drive the in-vehicle load.

6. The in-vehicle device according to claim 4, wherein even if the control unit outputs the suppression instruction signal to all of the downstream switching devices, if the voltage value across the upstream switching device remains above a threshold value, the control unit outputs the sleep instruction signal.

7. A program that controls the opening and closing of an upstream switchgear provided on a power line from a power supply unit mounted on a vehicle, and causes a computer that is communicatively connected to an on-board ECU provided on the power line downstream of the upstream switchgear in the direction of current flow from the power supply unit to execute processing, wherein the program determines whether or not a half-on fault has occurred in the upstream switchgear, and if it is determined that a half-on fault has occurred, the program executes processing to output instruction signals to the on-board ECU in stages to suppress power consumption.

8. An information processing method that controls the opening and closing of an upstream switchgear provided on a power line from a power supply unit mounted on a vehicle, and causes a computer, which is connected to a vehicle-mounted ECU on the power line downstream of the upstream switchgear in the direction of current flow from the power supply unit, to perform processing, wherein the method determines whether or not a half-on fault has occurred in the upstream switchgear, and if it is determined that a half-on fault has occurred, the method causes the vehicle-mounted ECU to perform processing by outputting instruction signals to suppress power consumption in stages.

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