Power supply system and method for controlling a power supply system

Abstract

A power supply system (100) mounted in a vehicle comprises a first load circuit (1), a second load circuit (2), a first relay (4), a second relay (5), and a controller (6). The first load circuit (1) is operated by power from a main battery (11) and is connected to a first load (12) necessary for the continuation of a normal driving mode by a driver. The second load circuit 2 is operated by power from the main battery (11) or an additional battery (21) and is connected to second loads (22 to 24) necessary for the continuation of an autonomous driving mode. The first relay (4) is provided in a feed line (3) connecting the first load (12) and the second loads (22-24), and conducts or interrupts electricity between the first load circuit (1) and the second load circuit (2). The second relay (5) conducts or interrupts electricity between the additional battery (21) and the second loads (22-24). The controller (6) determines the state of a switch (68) for starting the vehicle.

Description

Technical Field

[0001] The present invention relates to a power supply system and a control method for the power supply system.

Background Art

[0002] Conventionally, a control method for an automatic driving vehicle power supply having a circuit interruption mechanism between a first load circuit powered by a main battery and a second load circuit powered by an additional battery has been known (Patent Document 1). A load necessary for the driver to continue the normal driving mode is connected to the first load circuit, and an automatic driving function load necessary for continuing the automatic driving mode and requiring voltage maintenance is connected to the second load circuit. In this control method for the automatic driving vehicle power supply, when it is determined that power is taken from the additional battery to the first load circuit side based on the load state detected on the second load circuit side while the circuit interruption mechanism is connected, the circuit interruption mechanism is cut off.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the control method for the automatic driving vehicle power supply described in Patent Document 1, since the additional battery and the load cannot be disconnected, there is a problem that the additional battery discharges due to the leakage current of the load.

[0005] The problem to be solved by the present invention is to provide a power supply system and a control method for the power supply system that prevent the additional battery from discharging due to the leakage current of the load.

Means for Solving the Problems

[0006] The present invention operates by the power from the main battery,First A first load circuit to which a load is connected, operating with power from a main battery or an auxiliary battery, First a second load circuit to which a load is connected, provided in a power supply line electrically connecting the first load and the second load, First a first relay that conducts or cuts off between the first load circuit and the second load circuit, a second relay that conducts or cuts off between the auxiliary battery and the second load, and a controller that determines the state of a start switch for starting the vehicle, thereby solving the above problems.

Advantages of the Invention

[0007] According to the present invention, since the second relay can cut off between the auxiliary battery and the load, it is possible to prevent the discharge of the auxiliary battery due to the leakage current of the load.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2A

Figure 2B

Figure 3

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of a power supply system and a control method of the power supply system according to the present invention will be described with reference to the drawings.

[0010] FIG. 1 is a schematic configuration diagram of a power supply system 100 according to the present embodiment. In the present embodiment, as a vehicle equipped with the power supply system 100, a vehicle having an engine as a drive source and equipped with an autonomous driving control function will be described as an example. A vehicle equipped with an autonomous driving control function has a normal driving mode and an automatic driving mode as driving modes. When set to the normal driving mode, the vehicle travels by a driving operation (such as a steering operation, an accelerator operation, a brake operation, etc.) by a driver. On the other hand, when set to the automatic driving mode, the vehicle travels by a driving operation by a driving support device (not shown) in addition to the driver.

[0011] In the automatic driving mode, depending on the driving support level, the content of the driving support realized by the autonomous driving control function may be different. The driving support level is a level indicating the degree of intervention when the driving support device supports the driving of the vehicle by the autonomous driving control function. The higher the driving support level, the lower the contribution of the driver to the driving of the vehicle. Specifically, the driving support level can be set using definitions based on SAE J3016 of the Society of Automotive Engineers (SAE). In the present embodiment, the driving support level realized by the driving support device will be described as the driving support level 2. Further, in the present embodiment, a vehicle having a mode in which the vehicle autonomously travels without the driver touching the steering wheel (also referred to as a hands-off mode) will be described as an example. In the hands-off mode, instead of the driver, the driving support device executes some driving tasks, but the driver needs to take back the control of the driving and be prepared to drive manually when requested by the driving support device. Also, in the hands-off mode, a redundant function for continuing autonomous driving is required until the driver performs a driving operation in response to a request from the driving support device. As an example of the redundant function, for example, a vehicle having an automatic driving mode is provided with an additional battery that functions as a backup power supply for the load required for the autonomous driving control function.

[0012] However, by mounting an additional battery, there is also a problem that the additional battery is discharged by the leakage current of the load connected to the additional battery while the ignition switch of the vehicle is off. When the discharge of the additional battery progresses due to the leakage current of the load, the remaining battery level of the additional battery decreases, and in the automatic driving mode, the power necessary for continuing the autonomous driving cannot be supplied to the load, and there are cases where it does not function as a backup power supply. In the power supply system and the control method of the power supply system according to the present invention, by the configuration and method described below, the discharge of the additional battery due to the leakage current of the load is prevented, and in the automatic driving mode, the power necessary for continuing the autonomous driving can be supplied to the load. Hereinafter, the above-described driving support device will be described as a configuration included in an Advanced Driver Assistance System (ADAS).

[0013] As shown in FIG. 1, the power supply system 100 includes a first load circuit 1, a second load circuit 2, a power supply line 3, a main relay 4, an additional relay 5, and a controller 6.

[0014] The first load circuit 1 operates by the power from the lead battery 11 (main battery) or the alternator 14, and is a load circuit to which the first load necessary for continuing the normal driving mode is connected. In the present embodiment, as shown in FIG. 1, the first load circuit 1 includes a lead battery 11 connected to the power supply line 3, a load actuator 12, a starter motor 13, and an alternator 14. Examples of the first load necessary for continuing the normal driving mode include the load actuator 12 and the starter motor 13.

[0015] The lead battery 11 is a secondary battery that has been conventionally mounted on an engine vehicle as a main battery. The lead battery 11 is charged by an alternator 14 as a generator so that the remaining battery level does not decrease. The alternator 14 generates electricity by a rotation drive mechanism (not shown) by the engine, and charges the lead battery 11 so that the remaining battery level is maintained at or above a predetermined remaining battery level.

[0016] The load actuator 12 is an auxiliary machine that operates by the power from the lead battery 11 or the power generated by the alternator 14. Examples of the load actuator 12 include an electric motor that drives a compressor of an air conditioner, a headlight, etc. In a state where the ignition switch 68 of the vehicle is on (hereinafter also referred to as a state where the vehicle can run), the power stored in the lead battery 11 or the power generated by the alternator 14 is supplied to the load actuator 12. On the other hand, in a state where the ignition switch 68 of the vehicle is off (hereinafter also referred to as a state where the vehicle is parked), the power stored in the lead battery 11 is supplied to the load actuator 12. Note that the state where the vehicle can run indicates a state independent of the vehicle speed of the vehicle, and includes a state where the vehicle is running and a state where the vehicle is stopped.

[0017] The starter motor 13 is a motor for starting the engine at the start of the vehicle and restarting the engine at the time of idling stop.

[0018] The second load circuit 2 operates by the power from the lead battery 11 or the lithium ion battery 21 (additional battery), and is a load circuit to which a second load necessary for continuing the above-described automatic driving mode is connected. In the present embodiment, as shown in FIG. 1, the second load circuit 2 includes an EPS actuator 22, an ABS actuator 23, an ADAS actuator 24, and a current sensor 61 connected to the power supply line 3. Examples of the second load necessary for continuing the automatic driving mode include the EPS actuator 22, the ABS actuator 23, and the ADAS actuator 24. The range of the input voltage to these actuators is determined according to the specifications of each actuator, and in order to keep the actuators operating according to the specifications, it is necessary to maintain the input voltage to each actuator within the range of the input voltage defined by the specifications.

[0019] The lithium-ion battery 21 is a secondary battery added as a new power source to continue the autonomous driving control function of the vehicle with respect to the power supply by the lead battery 11. In other words, the lithium-ion battery 21 is a backup power supply that supplies power to each load included in the second load circuit 2 in order to continue autonomous driving in the automatic driving mode. The charging and discharging of the lithium-ion battery 21 are controlled by a battery management system (BMS). In the example of FIG. 1, when the main relay 4 and the additional relay 5 are in the on state, since conduction is established between the lithium-ion battery 21 and the first load circuit 1, the battery management system charges the lithium-ion battery 21 with the power generated by the alternator 14 (generator). As will be described later, when the controller 6 determines that the driving mode of the vehicle is the automatic driving mode, if the circuit voltage of the second load circuit 2 goes out of a predetermined voltage range, the main relay 4 switches from on to off. However, since the additional relay 5 maintains the on state, conduction is maintained between the additional battery and the second load circuit before and after the main relay 4 switches from on to off. The battery management system outputs the power charged in the lithium-ion battery 21 to the second load and discharges the lithium-ion battery 21. Once the main relay 4 switches from on to off in the automatic driving mode, the main relay 4 maintains the off state until shifting from the automatic driving mode to the normal driving mode, so the lithium-ion battery 21 cannot be charged with the power generated by the alternator 14. For this reason, the capacity of the lithium-ion battery 21 is set to an appropriate capacity so that, for example, the time to continue driving in the automatic driving mode is at least the required time or more.

[0020] Also, the lithium-ion battery 21 has a characteristic of having a smaller internal resistance than the lead battery 11. For this reason, for example, even when the EPS actuator 22 operates and consumes a large current, the voltage can be kept high.

[0021] The EPS actuator 22 is an EPS motor that generates an electric assist force and is a load that needs to operate in the automatic driving mode. The EPS actuator 22 is used in an electric power steering system (not shown) that electrically assists the force required for steering operation to lighten the steering force. Here, "EPS" is an abbreviation for "Electric Power Steering".

[0022] The ABS actuator 23 is a pump motor or an electromagnetic valve that drives a hydraulic pump and is a load that needs to operate in the automatic driving mode. The ABS actuator 23 has an electric hydraulic pump and is used in a brake hydraulic pressure control system (not shown) that independently controls the hydraulic pressure of each wheel cylinder based on the hydraulic oil from the master cylinder and the hydraulic pump. Here, "ABS" is an abbreviation for "Antilock Brake System".

[0023] The ADAS actuator 24 is an actuator that performs various driving operation supports to assist the driver's driving operation and is a load that needs to operate in the automatic driving mode. The ADAS actuator 24 is used in the advanced driving assistance system 70.

[0024] The power supply line 3 is a wire harness that electrically connects the first load circuit 1 and the second load circuit 2 for power supply. Power is supplied to the load actuator 12 included in the first load circuit 1, and the EPS actuator 22, the ABS actuator 23, and the ADAS actuator 24 included in the second load circuit 2 via the power supply line 3.

[0025] The main relay 4 is provided on the power supply line 3 between the first load circuit 1 and the second load circuit 2, and is a circuit interrupting mechanism for conducting or interrupting between the first load circuit 1 and the second load circuit 2. One terminal of the main relay 4 is connected to the power supply line 3 on the first load circuit 1 side, and the other terminal of the main relay 4 is connected to the power supply line 3 on the second load circuit 2 side. In this embodiment, as the main relay 4, a normally open type relay is used. Examples of the main relay 4 include a mechanical relay (also referred to as a mechanical type relay), a semiconductor relay, and the like. A mechanical relay has contacts and mechanically opens and closes the contacts by electromagnetic action to switch on and off. A semiconductor relay is composed of semiconductors and electronic components such as MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) without having contacts, and switches on and off by an electrical signal. In this embodiment, as the main relay 4, a semiconductor relay having a self-shutting / connecting function that autonomously switches on and off for overvoltage protection and overcurrent protection will be described as an example.

[0026] An opening / closing control signal is input from the controller 6 to the main relay 4, and the main relay 4 turns on or off according to the input opening / closing control signal. Further, a conduction maintenance command or a release command is input from the controller 6 to the main relay 4 separately from the opening / closing control signal. Once a conduction maintenance command is input to the main relay 4, it continuously maintains the on state regardless of the presence or absence of the input of the opening / closing control signal until a release command is input. When a release command is input after the input of the conduction maintenance command, the main relay 4 releases the maintenance of the on state and turns on or off again according to the opening / closing control signal. When the main relay 4 is a semiconductor relay as in the present embodiment, the opening / closing control signal is, for example, a switching signal for switching a semiconductor such as a switching element from on to off or from off to on. The conduction maintenance command is, for example, a signal for maintaining the on state by invalidating the self-cutoff / connection function in order to prevent switching from on to off by the self-cutoff / connection function. The release command is, for example, a signal for validating the self-cutoff / connection function. Examples of the self-cutoff / connection function include a protection function for switching the main relay 4 from on to off when the voltage applied between the terminals of the main relay 4 (between the terminal connected to the first load circuit 1 and the terminal connected to the second load circuit 2) is an abnormal voltage. The abnormal voltage is, for example, a predetermined overvoltage defined by the specifications of the main relay 4. Examples of the self-cutoff / connection function also include a protection function for switching the main relay 4 from on to off when the current flowing through the main relay 4 (the current flowing from the first load circuit 1 side to the second load circuit 2 side) is an abnormal current. The abnormal current is, for example, a predetermined overcurrent defined by the specifications of the main relay 4. In the following description, "the on (on state) of the main relay 4" represents a state in which the terminals of the main relay 4 are conducting, and "the off (off state) of the main relay 4" represents a state in which the terminals of the main relay 4 are insulated (cut off).

[0027] In this embodiment, as the main relay 4, a semiconductor relay having a self-diagnosis function for autonomously performing a failure diagnosis in addition to the self-cutoff / connection function will be described as an example. When a failure diagnosis start signal is input from the controller 6 to the main relay 4, the main relay 4 performs a failure diagnosis by its self-diagnosis function. In this embodiment, as the failure diagnosis of the main relay 4, a diagnosis of whether or not an on-sticking in which the main relay 4 is stuck in the on state (also referred to as a diagnosis of an on-sticking failure or a short-circuit failure) will be described as an example. The diagnosis of the on-sticking failure of the main relay 4 will be described later.

[0028] The additional relay 5 is electrically connected to the power supply line 3 on the second load circuit 2 side, and is a battery interrupter mechanism for conducting or interrupting between the lithium ion battery 21 and the EPS actuator 22, the ABS actuator 23, and the ADAS actuator 24. One terminal of the additional relay 5 is connected to the lithium ion battery 21, and the other terminal of the additional relay 5 is connected to the power supply line 3 on the second load circuit 2 side via the current sensor 61. In this embodiment, a normally closed type relay is used as the additional relay 5. As the additional relay 5, similar to the main relay 4, for example, a mechanical relay, a semiconductor relay, or the like can be mentioned. In this embodiment, a mechanical relay will be described as an example of the additional relay 5.

[0029] An opening / closing control signal is input from the controller 6 to the additional relay 5, and the additional relay 5 turns on or off according to the input opening / closing control signal. In addition to the opening / closing control signal, a conduction maintenance command or a release command is input from the controller 6 to the additional relay 5. Once a conduction maintenance command is input, the additional relay 5 continues to maintain the on state regardless of the presence or absence of the input of the opening / closing control signal until a release command is input. When a release command is input after the input of the conduction maintenance command, the additional relay 5 releases the maintenance of the on state and turns on or off again according to the opening / closing control signal. When the additional relay 5 is a mechanical relay as in this embodiment, the opening / closing control signal is, for example, a voltage application signal for generating a magnetic field to switch from off to on, and a voltage stop signal for disappearing the magnetic field to switch from on to off. The conduction maintenance command is, for example, a forced voltage application signal for continuously generating a magnetic field to maintain the on state. In the following description, "on (on state) of the additional relay 5" represents a state where the terminals of the additional relay 5 are conducting, and "off (off state) of the additional relay 5" represents a state where the terminals of the additional relay 5 are insulated (blocked state).

[0030] Also, in this embodiment, the conduction or interruption of the additional relay 5 by the opening / closing control signal is taken as an example for explanation, but the conduction or interruption between the lithium-ion battery 21 and each load included in the second load circuit 2 may be performed by other methods. For example, as a power supply system, a DCDC converter may be provided between the lithium-ion battery 21 and the additional relay 5, and a configuration in which the voltage of the lithium-ion battery 21 is boosted by the DCDC converter and output is also conceivable. In the case of this configuration, since the DCDC converter alone can function as a relay, the conduction or interruption between the lithium-ion battery 21 and the additional relay 5 may be performed by controlling the DCDC converter.

[0031] Next, the controller 6 will be described. The controller 6 is composed of a computer equipped with hardware and software, and is an electronic control unit (ECU) having a memory storing programs and a CPU or the like that executes the programs stored in this memory. Note that as the operation circuit, an MPU, a DSP, an ASIC, an FPGA, or the like can be used instead of or together with the CPU. The controller 6 realizes various functions by the CPU executing the programs stored in the ROM. The functions realized by the controller 6 will be described later.

[0032] As shown in FIG. 1, various types of information are input to the controller 6 from a current sensor 61, an automatic driving mode switch 62, a first voltage sensor 63, a second voltage sensor 64, a battery voltage sensor 65, a brake switch 66, a torque sensor 67, an ignition switch 68, a vehicle speed sensor 69, and an advanced driving assistance system 70. Further, the controller 6 executes processing based on the input information, and outputs an opening / closing control signal, a conduction maintenance command, or a release command to the main relay 4 and / or the additional relay 5 based on the execution result. Furthermore, the controller 6 executes processing based on the input information, and outputs a control command to the display device 71 and the buzzer 72 based on the execution result. Also, the controller 6 executes processing based on the input information, and performs a failure diagnosis of the main relay 4 based on the execution result.

[0033] The current sensor 61 is provided between the main relay 4 and the additional relay 5, and detects the direction of the current with respect to the lithium ion battery 21. The detection result by the current sensor 61 is output to the controller 6. Also, as in this embodiment, when the main relay 4 is a semiconductor relay having a self-diagnosis function, the detection result by the current sensor 61 is also output to the main relay 4.

[0034] The automatic driving mode switch 62 is a switch that can be operated by the driver and is a switch for starting the automatic driving mode. When the driving mode of the vehicle is the normal driving mode, the driver turns on the automatic driving mode switch 62 to start the automatic driving mode. Also, when the driving mode of the vehicle is the automatic driving mode, the driver turns off the automatic driving mode switch 62 to start the normal driving mode. The form, installation position, etc. of the automatic driving mode switch 62 are not particularly limited, but as an example of the automatic driving mode switch 62, a button provided on the steering wheel and operable by the driver can be mentioned. Information on the operation of the automatic driving mode switch 62 by the driver is output to the controller 6 and the advanced driver assistance system 70.

[0035] The first voltage sensor 63 detects the circuit voltage of the first load circuit 1. The circuit voltage of the first load circuit 1 is the voltage of the power supply line 3 on the first load circuit 1 side. The first voltage sensor 63 is connected in parallel, for example, to each component included in the first load circuit 1. The detection result by the first voltage sensor 63 is output to the controller 6. Also, when a semiconductor relay having a self-cutoff / connection function is used as the main relay 4 as in this embodiment, the detection result by the first voltage sensor 63 is also output to the main relay 4.

[0036] The second voltage sensor 64 detects the circuit voltage of the second load circuit 2. The circuit voltage of the second load circuit 2 is the voltage of the power supply line 3 on the second load circuit 2 side. The second voltage sensor 64 is connected in parallel, for example, to each load included in the second load circuit 2. The detection result by the second voltage sensor 64 is output to the controller 6. Also, when a semiconductor relay having a self-cutoff / connection function is used as the main relay 4 as in this embodiment, the detection result by the second voltage sensor 64 is also output to the main relay 4.

[0037] The battery voltage sensor 65 detects the battery voltage of the lithium-ion battery 21. The detection result by the battery voltage sensor 65 is output to the controller 6. The brake switch 66 detects the brake operation by the driver. The information on the brake operation by the driver detected by the brake switch 66 is output to the controller 6. The torque sensor 67 detects the steering torque applied to the steering shaft by the driver's steering operation. The information on the steering operation by the driver detected by the torque sensor 67 is output to the controller 6.

[0038] The ignition switch 68 is a start switch (also called a main power switch) for starting the vehicle. In the case of a vehicle whose drive source is an engine as in this embodiment, when the ignition switch 68 is turned on, the engine starts and the vehicle becomes drivable. On the other hand, when the ignition switch 68 is turned off, the engine stops and the vehicle is in a parked state. Examples of the type of ignition switch 68 include an engine key type in which the vehicle is started by the occupant turning the vehicle key inserted into the keyhole, and a push start type in which the vehicle is started by the occupant pressing a button shape. In addition to the display for starting the drive source of the vehicle (ON display) or the display for stopping the drive source of the vehicle (OFF display), the ignition switch 68 may be provided with a display (ACC display) for energizing an electrical system such as a car navigation Ge -tion or audio that has nothing to do with the running of the vehicle, a display (START display) for driving the starter motor 13 and enabling the start of the air conditioning system, etc. The information on the operation of the ignition switch 68 by the driver is output to the controller 6. The vehicle speed sensor 69 detects the vehicle speed of the vehicle. The detection result by the vehicle speed sensor 69 is output to the controller 6.

[0039] The advanced driving assistance system 70 is a system for assisting the driver's driving by performing automatic braking control, auto cruise control, lane keep control, etc. The processing result in the advanced driving assistance system 70 is output to the controller 6. The display device 71 displays a warning message to inform the driver that some abnormality has occurred in the automatic driving mode and to prompt the driver to perform a driving operation. The buzzer 72 outputs a warning sound to inform the driver that some abnormality has occurred in the automatic driving mode and to prompt the driver to perform a driving operation.

[0040] Next, the functions realized by the controller 6 will be described with reference to FIGS. 2A, 2B, and 3. FIGS. 2A and 2B are flowcharts showing an example of the procedure of the control method of the power supply system 100 executed by the controller 6 shown in FIG. 1. Note that the procedure of this control method starts from the state where the ignition switch 68 is off (the parked state of the vehicle).

[0041] In step S1, the controller 6 outputs a close control signal (hereinafter simply referred to as a close control signal) for turning on the relay to the main relay 4, and outputs an open control signal (hereinafter simply referred to as an open control signal) for turning off the relay to the additional relay 5. In the parked state of the vehicle, if conduction occurs between the additional relay 5 and each load included in the second load circuit 2, the lithium-ion battery 21 is discharged by the dark current of the load. By the processing in this step, conduction between the additional relay 5 and each load included in the second load circuit 2 is interrupted, so that the discharge of the lithium-ion battery 21 due to the dark current of the load can be prevented.

[0042] Here, in the flowcharts shown in FIGS. 2A and 2B, the processing of the controller 6 performed before outputting the open control signal to the main relay 4 or the additional relay 5 will be described. In the present embodiment, the controller 6 performs opening / closing control of the main relay 4 and the additional relay 5 so that at least one of the main relay 4 and the additional relay 5 is turned on. Specifically, the controller 6 acquires information regarding the states of the main relay 4 and the additional relay 5, and when the additional relay 5 is in the off state, does not output the open control signal to the main relay 4, and when the main relay 4 is in the off state, does not output the open control signal to the additional relay 5. This processing is to prevent both the main relay 4 and the additional relay 5 from being in the off state and the power supply to each load included in the second load circuit 2 from being interrupted.

[0043] Examples of the information regarding the states of the main relay 4 and the additional relay 5 include the detection results of the current sensor 61, and the controller 6 determines the states of the main relay 4 and the additional relay 5 from the detection results of the current sensor 61. Ru

[0044] For example, when the current direction detected by the current sensor 61 (hereinafter referred to as the detected current direction) is in the direction to the lithium ion battery 21, the controller 6 determines that both the main relay 4 and the additional relay 5 are in the on state. Further, when the detected current direction is in the direction from the lithium ion battery 21 to the first load circuit 1, the controller 6 may determine that both the main relay 4 and the additional relay 5 are in the on state. Further, when the detected current direction is in the direction from the lithium ion battery 21 to each load included in the second load circuit 2, the controller 6 determines that the main relay 4 is in the off state and the additional relay 5 is in the on state. Further, when the detected current direction is not in any direction, the controller 6 determines that at least the additional relay 5 is in the off state. Note that the determination method using the detection result of the current sensor 61 is merely an example. For example, when signals indicating the on state or the off state can be obtained from each of the main relay 4 and the additional relay 5, the controller 6 may determine the states of the main relay 4 and the additional relay 5 based on the signals obtained from the main relay 4 and the additional relay 5. In the description of the subsequent steps, when the controller 6 outputs an open control signal to the main relay 4 or the additional relay 5, it is assumed that the controller 6 has executed the above-described processing before the output of the open control signal.

[0045] Returning to FIG. 2A, in step S2, the controller 6 determines whether the vehicle is in a parked state based on the operation information from the ignition switch 68. When the controller 6 obtains an on signal indicating that the drive source of the vehicle is activated from the ignition switch 68, it determines that the vehicle is not in a parked state, assuming that the vehicle has shifted from the parked state to the drivable state. On the other hand, when the controller 6 obtains an off signal indicating that the drive source of the vehicle is stopped from the ignition switch 68, it determines that the vehicle is in a parked state. If the determination by the controller 6 is negative, the process proceeds to step S3. If the determination by the controller 6 is positive, the process waits in step S2 until a negative determination is made, that is, until the ignition switch 68 is turned on and the vehicle becomes drivable. While the process of the controller 6 is waiting in step S2, since the additional relay 5 is turned off by the process of step S1, it is possible to prevent the discharge of the lithium-ion battery 21 due to the dark current of the load. Note that the method for determining whether the vehicle is in a parked state is not limited to the determination method based on the operation information from the ignition switch 68, and other known determination methods at the time of filing this application may also be used.

[0046] When the process proceeds to step S3, the process of the controller 6 proceeds to step S31 of the subroutine shown in FIG. 3. FIG. 3 is a flowchart showing an example of the subroutine of step S3 shown in FIG. 2A.

[0047] In step S31, the controller 6 outputs a conduction maintenance command to the additional relay 5. When the additional relay 5 is conducting MaintainIt is switched from off to on by a command, and conduction is established between the lithium-ion battery 21 and the power supply line 3 on the second load circuit 2 side. As described for the additional relay 5, the conduction maintenance command is a command having a force to maintain the on state. Therefore, for example, even if an opening / closing control signal is input to the additional relay 5 for some reason, if the conduction maintenance command has been input to the additional relay 5 before that, the additional relay 5 ignores the input opening / closing control signal and forcibly maintains the on state by the conduction maintenance command. Before the failure diagnosis of the main relay 4 is executed, in this step, the controller 6 maintains the additional relay 5 in the on state. Also, until the controller 6 outputs a release command to the additional relay 5, the controller 6 outputs a conduction maintenance command to the additional relay 5 at a predetermined cycle (for example, every 100 ms). Thereby, during the execution of the failure diagnosis of the main relay 4 in step S33 described later, the possibility that the additional relay 5 turns off can be further reduced.

[0048] In step S32, the controller 6 outputs an opening control signal to the main relay 4. When no on-stuck fault has occurred in the main relay 4, the main relay 4 switches from on to off, and the connection between the first load circuit 1 and the second load circuit 2 is interrupted. Even if the connection between the first load circuit 1 and the second load circuit 2 is interrupted due to the turning off of the main relay 4, by the processing in step S31, the voltage of the lithium-ion battery 21 is applied to the terminal on the second load circuit 2 side of the main relay 4. Also, the voltage of the lithium-ion battery 21 is applied to each load included in the second load circuit 2. On the other hand, when an on-stuck fault has occurred in the main relay 4, the main relay 4 does not switch from on to off, and the connection between the first load circuit 1 and the second load circuit 2 remains conductive.

[0049] In step S33, the controller 6 outputs a fault diagnosis start signal to the main relay 4. In the present embodiment, the main relay 4 triggers the execution of a self-diagnosis function based on the input of the fault diagnosis start signal to perform a fault diagnosis. For example, based on the detection results of the first voltage sensor 63 and the second voltage sensor 64, the main relay 4 determines whether the voltage difference between the circuit voltage of the first load circuit 1 and the circuit voltage of the second load circuit 2 is equal to or greater than a predetermined determination voltage. The determination voltage is a voltage threshold defined for determining an on-stuck fault of the relay. When the voltage difference between the circuit voltage of the first load circuit 1 and the circuit voltage of the second load circuit 2 is equal to or greater than the predetermined determination voltage, the main relay 4 determines that no on-stuck fault has occurred. On the other hand, when the voltage difference between the circuit voltage of the first load circuit 1 and the circuit voltage of the second load circuit 2 is less than the predetermined determination voltage, the main relay 4 determines that an on-stuck fault has occurred. Also, for example, based on the detection result of the current sensor 61, the main relay 4 may determine whether current is flowing from the first load circuit 1 side to the second load circuit 2 side via the main relay 4. When current is flowing from the first load circuit 1 side to the second load circuit 2 side via the main relay 4, the main relay 4 determines that an on-stuck fault has occurred. On the other hand, when no current is flowing from the first load circuit 1 side to the second load circuit 2 side via the main relay 4, the main relay 4 determines that no on-stuck fault has occurred. The execution result of the fault diagnosis by the main relay 4 is output to the controller 6.

[0050] In step S34, the controller 6 determines whether the main relay 4 is faulty based on the result of the fault diagnosis in step S33. When the controller 6 obtains a diagnosis result in step S33 that no on-stuck fault has occurred as the fault diagnosis result, the controller 6 determines that the main relay 4 is not faulty. On the other hand, when the controller 6 obtains a diagnosis result in step S33 that an on-stuck fault has occurred as the fault diagnosis result, the controller 6 determines that the main relay 4 is faulty. When a negative determination is made by the controller 6, the process proceeds to step S35, and when an affirmative determination is made by the controller 6, the process proceeds to step S36.

[0051] In step S35, the controller 6 outputs a closing control signal to the main relay 4 and the additional relay 5. Further, the controller 6 outputs a release command for the conduction maintenance command output in step S31 to the additional relay 5. Since the conduction maintenance command has been input to the additional relay 5 by the process of step S31, the controller 6 may not output the closing control signal to the additional relay 5. When the process in step S35 ends, the controller exits the subroutine shown in FIG. 3 and proceeds to step S4 shown in FIG. 2A.

[0052] If an affirmative determination is made in step S34, the process proceeds to step S36. In step S36, the controller 6 outputs a command to prohibit the driving mode of the vehicle from being set to the autonomous driving mode to the advanced driving assistance system 70. When the advanced driving assistance system 70 acquires the command to prohibit setting the autonomous driving mode, for example, it invalidates the on signal from the autonomous driving mode switch 62. Further, the controller 6 may output a warning display signal to the display device 71 in order to notify the driver that setting the autonomous driving mode is prohibited due to a failure of the main relay 4. Further, the controller 6 may output a warning sound signal to the buzzer 72. Further, the controller 6 may output a warning display signal to the display device 71 and output a warning sound signal to the buzzer 72. This is to prohibit the vehicle from traveling in the autonomous driving mode because it has been determined that the main relay 4 has failed. When the process in step S36 ends, the controller exits the subroutine shown in FIG. 3 and proceeds to step S4 shown in FIG. 2A.

[0053] When the processing of step S35 or step S36 in FIG. 3 is completed, the process proceeds to step S4 in FIG. 2A. In step S4, the controller 6 determines whether the main relay 4 is faulty. For example, the controller 6 refers to the determination result of step S34 in FIG. 3 to determine whether the main relay 4 is faulty. If the controller 6 makes an affirmative determination, the process proceeds to step S13 shown in FIG. 2B. If the controller 6 makes a negative determination, the process proceeds to step S5. Note that in this embodiment, the vehicle can run not only when the ignition switch 68 is in the ON state but also when the fault diagnosis of the main relay 4 is completed. That is, the processing of step S3 is performed in the stopped state of the vehicle during the fault diagnosis of the vehicle.

[0054] In step S5, the controller 6 determines whether the driving mode of the vehicle is the automatic driving mode or the normal driving mode. For example, when the controller 6 obtains an ON signal from the automatic driving mode switch 62, the controller 6 may determine that the driving mode of the vehicle is the automatic driving mode. Also, when the controller 6 detects the output of a control signal for operating the load for each load included in the second load circuit 2, the controller 6 may determine that the driving mode of the vehicle is the automatic driving mode. Further, when the controller 6 obtains a signal indicating that each load included in the second load circuit 2 is in operation, the controller 6 may determine that the driving mode of the vehicle is the automatic driving mode. If the controller 6 corresponds to any one of the above-described examples, the controller 6 determines that the driving mode of the vehicle is the automatic driving mode. On the other hand, if none of the above-described examples apply to the controller 6, the controller 6 determines that the driving mode of the vehicle is the normal driving mode. When the driving mode of the vehicle is determined to be the automatic driving mode, the process proceeds to step S6. When the driving mode of the vehicle is determined to be the normal driving mode, the process proceeds to step S13 shown in FIG. 2B.

[0055] Note that, as a method for determining that the driving mode of the vehicle is the normal driving mode, a method for determining that it is not the automatic driving mode was described as an example, but the driving mode of the vehicle may be determined to be the normal driving mode by another method. For example, when the controller 6 acquires an off signal from the automatic driving mode switch 62, the driving mode of the vehicle may be determined to be the normal driving mode. Also, when the controller 6 acquires a signal of a braking operation by the driver from the brake switch 66, the driving mode of the vehicle may be determined to be the normal driving mode. Further, when the controller 6 acquires a signal of a steering operation by the driver from the torque sensor 67, the driving mode of the vehicle may be determined to be the normal driving mode. When the controller 6 corresponds to any one of the above-described examples, the driving mode of the vehicle may be determined to be the normal driving mode. Also, the controller 6 may acquire a driving mode signal indicating the driving mode of the vehicle from the advanced driving assistance system 70, and determine whether the driving mode of the vehicle is the automatic driving mode or the normal driving mode based on the driving mode signal. For example, when the advanced driving assistance system 70 acquires an on signal from the automatic driving mode switch 62, the driving mode of the vehicle is determined to be the automatic driving mode. Also, when the advanced driving assistance system 70 acquires an off signal from the automatic driving mode switch 62, the driving mode of the vehicle is determined to be the normal driving mode. The controller 6 may determine whether the driving mode of the vehicle is the automatic driving mode or the normal driving mode according to the driving mode signal acquired from the advanced driving assistance system 70.

[0056] In step S6, the controller 6 outputs a release command to the main relay 4 and outputs a conduction maintenance command to the additional relay 5. When it is determined that the driving mode of the vehicle is the autonomous driving mode, in this step, the controller 6 keeps the additional relay 5 in the on state. Also, until the controller 6 outputs a release command to the additional relay 5, the controller 6 outputs a conduction maintenance command to the additional relay 5 at a predetermined cycle (for example, every 100 ms). Thereby, in the autonomous driving mode, the possibility that the additional relay 5 turns off can be further reduced. On the other hand, for the main relay 4, the controller 6 outputs a release command to make the main relay 4 in a state controllable by an opening / closing control signal. As in this embodiment, when the main relay 4 is a semiconductor relay having a self-cutoff / connection function, the self-cutoff / connection function of the main relay 4 is activated by a release command.

[0057] In step S7, the controller 6 determines whether a voltage abnormality has occurred in the power supply system 100 based on the circuit voltage of the second load circuit 2. The controller 6 determines whether the circuit voltage on the additional battery side (the circuit voltage of the second load circuit 2) is outside a predetermined voltage range based on the detection result of the second voltage sensor 64. The predetermined voltage range is a range with the unit of voltage and is a predetermined range. The upper limit value in the predetermined voltage range is a voltage value determined to prevent overvoltage to each load included in the second load circuit 2, and the lower limit value in the predetermined range is a voltage value determined to operate each load included in the second load circuit 2 as specified. When a negative determination is made by the controller 6, that is, when it is determined that no voltage abnormality has occurred in the power supply system 100, the process proceeds to step S8. On the other hand, when an affirmative determination is made by the controller 6, that is, when it is determined that a voltage abnormality has occurred in the power supply system 100, the process proceeds to step S9.

[0058] In step S8, the controller 6 outputs a close control signal to the main relay 4 and the additional relay 5. In the example of FIG. 2A, step S8 is described for comparison with step S9. However, since the main relay 4 and the additional relay 5 are on due to the processing in step S3, the controller 6 may omit the processing in step S8. When the processing in step S8 is completed, the process returns to step S5, and again, the driving mode of the vehicle is determined. In a state where the vehicle can travel in the autonomous driving mode, when no voltage abnormality occurs in the power system 100, the processing from step S5 to step S8 is repeatedly executed, so both the main relay 4 and the additional relay 5 maintain the on state.

[0059] If an affirmative determination is made in step S7, the process proceeds to step S9. In step S9, the controller 6 outputs an open control signal to the main relay 4 and a close control signal to the additional relay 5. The main relay 4 switches from on to off when the circuit voltage of the second load circuit 2 goes out of a predetermined voltage range in the autonomous driving mode. On the other hand, in the autonomous driving mode, the additional relay 5 maintains the on state regardless of the circuit voltage of the second load circuit 2 even if the circuit voltage of the second load circuit 2 goes out of the predetermined voltage range due to the processing in step S6. Due to the switching of the main relay 4, the power supply from the first load circuit 1 side to each load included in the second load circuit 2 is cut off. However, since the additional relay 5 maintains the on state, power is supplied to each load included in the second load circuit 2 from the lithium-ion battery 21. That is, in the autonomous driving mode, each load included in the second load circuit 2 can continue to operate with the power from the lithium-ion battery 21 even if the power supply from the first load circuit 1 side is cut off. Since a conduction maintenance command is input to the additional relay 5 due to the processing in step S6, the controller 6 may not output a close control signal to the additional relay 5.

[0060] Also, in the case of the semiconductor relay in which the main relay 4 has a self-cutoff / connection function as in the present embodiment, the switching from on to off of the main relay 4 may be a switching by the self-cutoff / connection function of the main relay 4. For example, when the main relay 4 detects that the circuit voltage of the second load circuit 2 (the terminal voltage of the main relay 4 connected to the second load circuit 2) is outside a predetermined voltage range based on the detection result from the second voltage sensor 64, it may be switched from on to off by the self-cutoff / connection function. Since the main relay 4 is switched from on to off by the self-cutoff / connection function earlier than the open control signal is transmitted from the controller 6 to the main relay 4, the time during which the circuit voltage of the second load circuit 2 is outside the predetermined voltage range can be made shorter, and each load included in the second load circuit 2 can be better protected.

[0061] In step S10, in order for the controller 6 to notify the driver that an abnormality has occurred in the automatic driving mode, the controller 6 outputs a warning display signal to the display device 71. Further, the controller 6 may output a warning sound signal to the buzzer 72. Further, the controller 6 may output a warning display signal to the display device 71 and output a warning sound signal to the buzzer 72. By the processing in this step, the driver is prompted to shift from the automatic driving mode to the normal driving mode. In other words, this step is a step for requesting the driver to take back the control of the driving performed by the driving support device. Since the additional relay 5 maintains the on state by the processing in step S6, each load included in the second load circuit 2 operates with the power from the lithium ion battery 21, and the autonomous driving of the vehicle in the automatic driving mode continues.

[0062] Since the driver's operation intervention is a condition for canceling the automatic driving mode, when the driver performs driving operations such as braking, accelerating, and steering operations, in step S11, the controller 6 determines that the driving mode of the vehicle has shifted from the automatic driving mode to the normal driving mode. For example, when the controller 6 acquires a signal of a braking operation by the driver from the brake switch 66, or acquires a signal of a steering operation by the driver from the torque sensor 67, it determines that the automatic driving mode has been canceled and the driving mode of the vehicle has shifted to the normal driving mode.

[0063] In step S12, the controller 6 outputs a closing control signal to the main relay 4 and the additional relay 5. Since a conduction maintenance command has been input to the additional relay 5 by the process of step S6, the controller 6 may not output the closing control signal to the additional relay 5. Further, the controller 6 may output a cancellation command for the conduction maintenance command output in step S6 to the additional relay 5. When the process in step S12 is completed, the controller 6 ends the processes shown in FIGS. 2A and 2B.

[0064] In step S5, when it is determined that the driving mode of the vehicle is the normal driving mode, the process proceeds to step S13 shown in FIG. 2B. In step S13, the controller 6 outputs a conduction maintenance command to the main relay 4 and outputs a release command to the additional relay 5. As described for the main relay 4, the conduction maintenance command is a command having a force to maintain the on state. Therefore, for example, even if an opening / closing control signal is input to the main relay 4 for some reason, if the conduction maintenance command has been input to the main relay 4 before that, the main relay 4 ignores the input opening / closing control signal and forcibly maintains the on state by the conduction maintenance command. When it is determined that the driving mode of the vehicle is the normal driving mode, in this step, the controller 6 maintains the main relay 4 in the on state. Also, until the controller 6 outputs a release command to the main relay 4, the controller 6 outputs a conduction maintenance command to the main relay 4 at a predetermined cycle (for example, every 100 ms). Thereby, in the normal driving mode, the possibility that the main relay 4 turns off can be further reduced. In the case where the main relay 4 is a semiconductor relay having a self-cutoff / connection function as in the present embodiment, by this step, the self-cutoff / connection function of the main relay 4 is invalidated, so that it is possible to prevent the main relay 4 from switching from on to off due to the self-cutoff / connection function. On the other hand, for the additional relay 5, the controller 6 outputs a release command to make the additional relay 5 controllable by the opening / closing control signal.

[0065] In step S14, the controller 6 determines whether a voltage abnormality has occurred in the power supply system 100 based on the circuit voltage of the second load circuit 2. Since step S14 is a step corresponding to step S7, the description of step S7 is incorporated for the description of step S14. When a negative determination is made by the controller 6, that is, when it is determined that no voltage abnormality has occurred in the power supply system 100, the process returns to step S4 shown in FIG. 2A. On the other hand, when an affirmative determination is made by the controller 6, that is, when it is determined that a voltage abnormality has occurred in the power supply system 100, the process proceeds to step S15.

[0066] If a negative determination is made in step S14, the process returns to step S4, and again, it is determined whether the main relay 4 has failed. Regardless of whether the main relay 4 has failed, in a state where the vehicle can travel in the normal operation mode and no voltage abnormality occurs in the power supply system 100, the processes of step S4 (step S5), step S13, and step S14 are repeatedly executed, so both the main relay 4 and the additional relay 5 maintain the on state. Incidentally, if the ignition switch 68 is turned off while the processes of step S4 (step S5), step S13, and step S14 are repeatedly executed, the controller 6 determines that the vehicle has shifted from a state where it can travel to a parked state, and outputs a close control signal to the main relay 4 and an open control signal to the additional relay 5 in the same manner as the process of step S1. The main relay 4 maintains the on state while the additional relay 5 switches from on to off.

[0067] Here, a description will be given of the state of the power supply system 100 that may occur when the additional relay 5 is switched from on to off from a state where the first load circuit 1 and the second load circuit 2 are conducting and current is flowing from the first load circuit 1 side to the second load circuit side. For example, when the processes of step S5, step S13, and step S14 are repeatedly executed, since both the main relay 4 and the additional relay 5 maintain the on state, current from the first load circuit 1 side is input to the lithium-ion battery 21 via the additional relay 5. When the additional relay 5 is a mechanical relay as in the present embodiment, when the additional relay 5 is switched from on to off, a back electromotive force is generated in the additional relay 5 in an attempt to maintain the current flowing through the coil of the mechanical relay. The back electromotive force becomes a surge voltage that is instantaneously generated and is input to the main relay 4 via the power supply line 3. When the main relay 4 is a semiconductor relay having a self-cutoff / connection function as in the present embodiment, the main relay 4 may be switched from on to off by the self-cutoff / connection function when it detects the surge voltage. However, since the self-cutoff / connection function of the main relay 4 is disabled by the process in step S13 and the main relay 4 maintains the on state, even if the surge voltage is input to the main relay 4 due to the switching of the additional relay 5 from on to off, it is possible to prevent the main relay 4 from being switched from on to off. As a result, power can continue to be supplied to each load included in the second load circuit 2 from the first load circuit 1 side, and the circuit voltage of the second load circuit 2 can be maintained.

[0068] Returning to FIG. 2B, if an affirmative determination is made in step S14, the process proceeds to step S15. In step S15, the controller 6 outputs a closed control signal to the main relay 4 and an open control signal to the additional relay 5. The additional relay 5 switches from on to off when the circuit voltage of the second load circuit 2 falls outside a predetermined voltage range in the normal operation mode. On the other hand, in the normal operation mode, the main relay 4 maintains an on state regardless of the circuit voltage of the second load circuit 2 even if the circuit voltage of the second load circuit 2 falls outside the predetermined voltage range due to the processing in step S13. As described above, since the main relay 4 is in an on state and the additional relay 5 switches from on to off, there is a possibility that a surge voltage will be generated due to the switching of the additional relay 5 also in this step, but the main relay 4 maintains an on state by the processing in step S13. Since a conduction maintenance command has been input to the main relay 4 by the processing in step S13, the controller 6 may not output a closed control signal to the main relay 4.

[0069] In step S16, the controller 6 determines whether the voltage abnormality that occurred in step S14 continues based on the circuit voltage of the second load circuit 2. Whether it can be judged Since step S16 corresponds to the steps corresponding to step S7 and step S14, the descriptions of step S7 and step S14 are incorporated for the description of step S16. If a negative determination is made by the controller 6, that is, if it is determined that no voltage abnormality has occurred in the power supply system 100, the process proceeds to step S12 shown in FIG. 2A. On the other hand, if an affirmative determination is made by the controller 6, that is, if it is determined that the voltage abnormality in the power supply system 100 continues to occur, the process waits in step S16 until an affirmative determination is made.

[0070] While waiting in step S16, if the ignition switch 68 is turned off, the controller 6 determines that the vehicle has shifted from the drivable state to the parked state, and outputs a close control signal to the main relay 4 and an open control signal to the additional relay 5 in the same manner as the process of step S1. Further, the controller 6 may output a release command for the conduction maintenance command output in step S13 to the main relay 4.

[0071] If a negative determination is made in step S16, the process proceeds to step S12 shown in FIG. 2A. In step S12, the controller 6 outputs a close control signal to the main relay 4 and the additional relay 5. Since a conduction maintenance command has been input to the main relay 4 by the process of step S13, the controller 6 may not output a close control signal to the main relay 4. Further, the controller 6 may output a release command for the conduction maintenance command output in step S13 to the main relay 4. When the process in step S12 is completed, the controller 6 ends the processes shown in FIGS. 2A and 2B.

[0072] Note that when the process proceeds from step S16 to step S12 and then the ignition switch 68 is turned off, the controller 6 determines that the vehicle has shifted from the drivable state to the parked state, and outputs a close control signal to the main relay 4 and an open control signal to the additional relay 5 in the same manner as the process of step S1. Further, the controller 6 may output a release command for the conduction maintenance command output in step S13 to the main relay 4.

[0073] As described above, the power supply system 100 according to the present embodiment is a power supply system mounted on a vehicle having a normal operation mode and an automatic operation mode by a driver, and includes a first load circuit 1, a second load circuit 2, a main relay 4, an additional relay 5, and a controller 6. The first load circuit 1 operates by power from the lead battery 11 or the alternator 14, and the load actuator 12 and the starter motor 13 necessary for continuing the normal operation mode are connected thereto. The second load circuit 2 operates by power from the lead battery 11 or the lithium-ion battery 21, and the EPS actuator 22, the ABS actuator 23, and the ADAS actuator 24 necessary for continuing the automatic operation mode are connected thereto. The main relay 4 is provided in the power supply line 3 that electrically connects the first load circuit 1 and the second load circuit 2, and conducts or interrupts between the first load circuit 1 and the second load circuit 2. The additional relay 5 conducts or interrupts between the lithium-ion battery 21 and each load included in the second load circuit 2. In the present embodiment, the main relay 4 is in an on state when the ignition switch 68 is off, and the additional relay 5 is in an off state when the ignition switch 68 is off. When the controller 6 determines that the ignition switch 68 has been switched from off to on (at step S2 in FIG. 2A NO ), after turning on the additional relay 5 (step S31 in FIG. 3), the main relay 4 is turned off (step S32 in FIG. 3). The failure diagnosis of the main relay 4 is executed in a state where the main relay 4 is off and the additional relay 5 is on (step S33 in FIG. 3).

[0074] Since the additional relay 5 can interrupt between the lithium-ion battery 21 and each load included in the second load circuit 2, in the parked state of the vehicle, it is possible to prevent the lithium-ion battery 21 from discharging due to the leakage current of the load and the remaining battery level of the lithium-ion battery 21 from decreasing. As a result, even when a situation occurs in which the main relay 4 is turned off while the vehicle is capable of traveling in the automatic operation mode, the lithium-ion battery 21 can supply power for continuing autonomous driving to each load included in the second load circuit 2. Also, at the end of discharge StopThe lithium-ion battery 21 can be prevented from over-discharging, that is, the state where the lithium-ion battery 21 continues to discharge while the voltage is below a certain level. As a result, the deterioration of the lithium-ion battery 21 can be alleviated, and the battery life of the lithium-ion battery 21 can be extended.

[0075] Here, unlike the power supply system 100 according to the present embodiment, the time required until the failure diagnosis of the main relay is completed will be described using a power supply system according to a comparative example that does not include the additional relay 5 and the lithium-ion battery 21. The power supply system according to the comparative example has the same configuration as the power supply system 100, except that it does not include the additional relay 5 and the lithium-ion battery 21. In the power supply system according to the comparative example, when the ignition switch is switched from off to on while the main relay is on, the failure diagnosis of the main relay is executed with the first load circuit and the second load circuit being in a conductive state. After the vehicle is started, for example, due to voltage fluctuations of the alternator, it takes time for the circuit voltage of the first load circuit to converge to a predetermined voltage. Therefore, the failure diagnosis of the main relay cannot be executed until the circuit voltage of the first load circuit converges to the predetermined voltage, and it takes time to start the failure diagnosis of the main relay. That is, in the power supply system according to the comparative example, there is a problem that it takes time from when the vehicle is started until the failure diagnosis of the main relay is completed. However, in the power supply system 100 and the control method of the power supply system 100 according to the present embodiment, when the ignition switch 68 is switched from off to on, the additional relay 5 is turned on, so the voltage of the lithium-ion battery 21 is applied to the terminals of the main relay 4. Then, after the additional relay 5 is turned on, the main relay 4 is turned off, and the failure diagnosis of the main relay 4 is executed with the first load circuit 1 and the second load circuit 2 being in a disconnected state. After the vehicle is started, the voltage of the lithium-ion battery 21 fluctuates less than the output voltage of the alternator 14. Therefore, the voltage applied to the second load circuit 2 side of the main relay 4 converges earlier than the voltage applied to the first load circuit 1 side of the main relay 4. For this reason, the failure diagnosis of the main relay 4 can be executed based on the circuit voltage of the second load circuit 2 without waiting for the circuit voltage of the first load circuit 1 to stabilize. Compared with the case where the failure diagnosis of the main relay is executed based on the circuit voltage of the first load circuit 1 as in the comparative example, the failure diagnosis of the main relay 4 can be started earlier.That is, according to the power supply system 100 and the control method of the power supply system 100 of the present embodiment, it is possible to prevent the reduction of the battery remaining amount of the lithium-ion battery 21 due to dark current discharge and shorten the time until the failure diagnosis of the main relay 4 is completed.

[0076] Also, in the present embodiment, the controller 6 acquires information regarding the state of the main relay 4 and the state of the additional relay 5. When the additional relay 5 is in the off state, the controller 6 does not output an open control signal to the main relay 4. When the main relay 4 is in the off state, the controller 6 does not output an open control signal to the additional relay 5. Thereby, both the main relay 4 and the additional relay 5 are in the off state, and it is possible to prevent the power supply to each load included in the second load circuit 2 from being interrupted. Further, since it is only necessary to monitor the states of the main relay 4 and the additional relay 5 without requiring complicated processing, it is possible to prevent the power supply to the second load circuit 2 side from being cut off, thereby reducing the arithmetic load of the controller 6 and improving the processing speed.

[0077] Also, in the present embodiment, the controller 6 maintains the on state of the additional relay 5 during the execution of the failure diagnosis of the main relay 4. Thereby, during the execution of the failure diagnosis of the main relay 4, the conduction state is maintained between the lithium-ion battery 21 and each load included in the second load circuit 2. As a result, even if the failure diagnosis of the main relay 4 is executed in a state where the first load circuit 1 and the second load circuit 2 are disconnected, each load included in the second load circuit 2 can continue to be supplied with power from the lithium-ion battery 21, and the circuit voltage of the second load circuit 2 can be maintained.

[0078] Also, in the present embodiment, when the controller 6 determines that the main relay 4 has failed (YES in step S34 of FIG. 3), the controller 6 outputs a command to prohibit the vehicle operation mode from being set to the automatic operation mode. Thereby, it is possible to prohibit the vehicle from traveling in the automatic operation mode in a state where the main relay 4 has failed.

[0079] Note that the embodiments described above are provided to facilitate the understanding of the present invention, and are not provided to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[0080] In the above-described embodiment, the case where the failure diagnosis of the main relay 4 is completed and the driving mode of the vehicle is determined to be the normal driving mode (determined to be the normal driving mode in step S6 of FIG. 2A), and the on state of the additional relay 5 is maintained has been described. However, after the failure diagnosis of the main relay 4 is completed, the controller 6 may switch the additional relay 5 from on to off when the driving mode of the vehicle is determined to be the normal driving mode. Thereby, for example, in a stopped state of the vehicle, it is possible to prevent the lithium ion battery 21 from discharging with respect to the load connected to the lithium ion battery 21, and it is possible to prevent a decrease in the remaining battery level of the lithium ion battery 21.

[0081] In the above-described embodiment, the case where the failure diagnosis of the main relay 4 is executed after the ignition switch 68 is switched from off to on has been described. However, the failure diagnosis of the main relay 4 may be executed after the ignition switch 68 is switched from on to off. For example, the controller 6 determines whether the ignition switch 68 has been switched from on to off, and if it is determined that the ignition switch 68 has been switched from on to off, a failure diagnosis start signal may be output to the main relay 4. At this time, unlike step S33 in FIG. 3, the controller 6 may output the failure diagnosis start signal to the main relay 4 with the main relay 4 turned on. This is because the time required for the failure diagnosis of the main relay 4 to be completed may be long after the vehicle has shifted to the parking state. Further, when the failure diagnosis of the main relay 4 is executed after the ignition switch 68 is switched from on to off, the controller 6 determines whether the ignition switch 68 has been switched from off to on within a predetermined interval when the ignition switch 68 is next switched from off to on. Then, when the controller 6 determines that the ignition switch 68 has been switched from off to on within a predetermined interval, the controller 6 does not output the failure diagnosis start signal to the main relay 4 even if the ignition switch 68 is switched from off to on. The predetermined interval is a period determined based on the specifications of the main relay 4. It is possible to prevent the failure diagnosis of the main relay 4 from being executed within a short period, and the time from when the vehicle starts to when the vehicle starts to run can be shortened.

[0082] Also, in the above-described embodiment, in step S32 of FIG. 3, the case where the controller 6 switches the additional relay 5 from off to on without controlling the circuit voltage of the first load circuit 1 was described. However, the controller 6 may switch the additional relay 5 from off to on after controlling the circuit voltage of the first load circuit 1. For example, the controller 6 may set the circuit voltage of the first load circuit 1 to the voltage of the lithium-ion battery 21 by controlling the alternator 14 before turning on the additional relay 5. Then, after the circuit voltage of the first load circuit 1 corresponds to the voltage of the lithium-ion battery 21, the controller 6 may switch the additional relay 5 from off to on. Thereby, when the additional relay 5 is switched from off to on, it is possible to prevent an inrush current from flowing through the additional relay 5 due to the voltage difference between the circuit voltage of the first load circuit 1 and the voltage of the lithium-ion battery 21. As a result, it is possible to suppress the failure of the additional relay 5 and also to slow down the speed at which the contacts of the additional relay 5 wear. Note that after the additional relay 5 is turned on, the controller 6 controls the alternator 14 to set the circuit voltage of the first load circuit to the voltage for the vehicle to run in order to operate each load included in the first load circuit 1 according to the specifications.

[0083] Also, in the above-described embodiment, as the failure diagnosis of the main relay 4, the case where it is diagnosed whether or not an on-stuck has occurred in the main relay 4 was described. However, the failure diagnosis of the main relay 4 may be an on-stuck failure diagnosis and a diagnosis of whether or not an off-stuck that is stuck in the off state has occurred (also referred to as an off-stuck failure diagnosis or an open failure diagnosis). For example, after the on-stuck failure diagnosis is completed, the controller 6 outputs a close control signal to the main relay 4. The main relay 4 may execute a diagnosis of an off-stuck failure by its self-diagnosis function. For example, based on the detection result of the current sensor 61, the main relay 4 may determine from the first load circuit 1 side through the main relay 4 to the second load circuit 2Determine whether current is flowing in the lateral direction. When current is flowing from the first load circuit 1 side to the second load circuit 2 side through the main relay 4, the main relay 4 determines that no off-stuck fault has occurred. On the other hand, when no current is flowing from the first load circuit 1 side to the second load circuit 2 side through the main relay 4, the main relay 4 determines that an off-stuck fault has occurred. And when a diagnostic result indicating that at least one of the on-stuck fault and the off-stuck fault has occurred is obtained, the controller 6 determines that the main relay 4 is faulty. On the other hand, when a diagnostic result indicating that no faults have occurred is obtained, the controller 6 determines that the main relay 4 is not faulty.

[0084] Also, in the above-described embodiment, the case where the lead battery 11 is used as the main battery is shown. However, as the main battery, a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery may be used. Also, in the above-described embodiment, the case where the lithium-ion battery 21 is used as the additional battery is shown. However, as the additional battery, a plurality of batteries may be used, or a combination of a capacitor and a DCDC converter may be used, or a nickel-metal hydride battery may be used. Also, in the above-described embodiment, the case where the alternator 14 is used as the generator of the first load circuit 1 is shown. However, for the first load circuit 1As the generator, a generator, a motor generator, or the like may be used. In the above-described embodiment, the case where the EPS actuator 22, the ABS actuator 23, and the ADAS actuator 24 are used as the loads included in the second load circuit 2 is shown. However, the loads necessary for the continuation of the automatic driving mode may be changed according to the specifications of the vehicle and the driving support device. In the above-described embodiment, the case where the additional relay 5 and the lithium ion battery 21 are not included in the second load circuit 2 is shown. However, the second load circuit 2 may include the additional relay 5 and the lithium ion battery 21. In the above-described embodiment, the case where a semiconductor relay having a self-cutoff / connection function and a self-diagnosis function is used as the main relay 4 is shown. However, as the main relay 4, a semiconductor relay having no self-cutoff / connection function, a semiconductor relay having no self-diagnosis function, a semiconductor relay having neither a self-cutoff / connection function nor a self-diagnosis function, or a mechanical relay may be used. Note that Me When a semiconductor relay having no self-diagnosis function is used as the in-relay 4, the failure diagnosis of the main relay 4 is executed by the controller 6. For example, the controller 6 executes the failure diagnosis of the main relay 4 in step S33 of FIG. 3. The method of failure diagnosis is the same as that described in the above-described embodiment. In the above-described embodiment, the case where a mechanical relay is used as the additional relay 5 is shown. However, a semiconductor relay may be used as the additional relay 5.

[0085] In the above-described embodiment, the power supply system and the control method of the power supply system according to the present invention are described by taking as an example the case where they are applied to a vehicle having a hands-off mode at driving support level 2. However, the power supply system and the control method of the power supply system according to the present invention can also be applied to vehicles at driving support level 3.

[0086] In the above-described embodiment, the power supply system and the control method of the power supply system according to the present invention have been described by taking as an example the case where they are applied to a vehicle (engine vehicle) whose drive source is an engine. However, the power supply system and the control method of the power supply system according to the present invention can also be applied to a vehicle (electric vehicle) whose drive source is a battery, a vehicle (hybrid vehicle) whose drive source is an engine and a battery, and a vehicle (fuel cell vehicle) whose drive source is a fuel cell. In short, a first load circuit that operates by the power from the main battery and to which a first load necessary for continuing the normal operation mode is connected, and a second load circuit that operates by the power from the additional battery and to which a second load necessary for continuing the automatic operation mode is connected, and a first relay provided in a power supply line that electrically connects the first load and the second load and that conducts or cuts off between the first load circuit and the second load circuit, a second relay that conducts or cuts off between the additional battery and the second load, and a controller that determines the state of the ignition switch 68 can be applied to a vehicle equipped with a power supply system.

[0087] In the above-described embodiment, the control procedure of proceeding to step S12 after the driving mode of the vehicle has shifted from the automatic driving mode to the normal driving mode in step S11 of FIG. 2A has been described by taking as an example. However, after the process of step S11, it may proceed to step S13 shown in FIG. 2B in the same manner as when it is determined in step S5 that the driving mode of the vehicle is the normal driving mode.

[0088] In the above-described embodiment, the case where it is determined whether the circuit voltage of the second load circuit 2 is outside a predetermined voltage range in step S7 of FIG. 2A, steps S14 and S16 of FIG. 2B has been described. However, since the first load circuit 1 and the second load circuit 2 are electrically connected by the main relay 4 in any step, in each step, the controller 6 may determine whether the circuit voltage of the first load circuit 1 is outside a predetermined voltage range. Also, in the above-described embodiment, the case where the additional relay 5 is switched from on to off by the controller 6 when the circuit voltage of the second load circuit 2 is outside a predetermined voltage range in step S14 of FIG. 2B has been described. However, in the normal driving mode of the vehicle, the condition for switching the additional relay 5 from on to off may be that the current flowing through the additional relay 5 is equal to or greater than a predetermined current threshold. For example, when it is determined that the driving mode of the vehicle is the normal driving mode (determined as the normal driving mode in step S5 of FIG. 2A), the controller 6 compares the current flowing through the additional relay 5 with a predetermined current threshold based on the detection result from the current sensor 61. The direction of the current flowing through the additional relay 5 is not particularly limited, and the controller 6 compares the absolute value of the current flowing through the additional relay 5 with a predetermined current threshold. The predetermined current threshold is a current threshold determined based on the contact life of the additional relay 5 with the unit of current. When the absolute value of the current flowing through the additional relay 5 is equal to or greater than the predetermined current threshold, the controller 6 outputs an open control signal to the additional relay 5. Thereby, in the normal driving mode, when an excessive current flows through the additional relay 5, by switching the additional relay 5 from on to off, the speed at which the contacts of the additional relay 5 wear can be reduced.

[0089] In the above-described embodiment, as an example of the condition for the controller 6 to turn off the main relay 4 in step S7 of FIG. 2A, the condition that the circuit voltage of the second load circuit 2 is outside a predetermined voltage range was described. However, in step S7, the controller 6 may turn off the main relay 4 when the circuit voltage of the second load circuit 2 is lower than the lower limit value of the predetermined voltage range or when the circuit voltage of the second load circuit 2 is higher than the upper limit value of the predetermined voltage range. Similarly, in the above-described embodiment, as an example of the condition for the controller 6 to turn off the additional relay 5 in step S14 of FIG. 2B, the condition that the circuit voltage of the second load circuit 2 is outside a predetermined voltage range was described. However, in step S14, the controller 6 may turn off the additional relay 5 when the circuit voltage of the second load circuit 2 is lower than the lower limit value of the predetermined voltage range or when the circuit voltage of the second load circuit 2 is higher than the upper limit value of the predetermined voltage range.

Description of Reference Numerals

[0090] 1…First load circuit 11…Lead battery 12…Load actuator 13…Starter motor 14…Alternator 2…Second load circuit 21…Lithium-ion battery 22…EPS actuator 23…ABS actuator 24…ADAS actuator 3…Power supply line 4…Main relay 5…Additional relay 6…Controller 61…Current sensor 62…Autonomous driving mode switch 63…First voltage sensor 64…Second voltage sensor 65…Battery voltage sensor 66…Brake switch 67…Torque sensor 68…Ignition switch 69…Vehicle speed sensor 70…Advanced driving assistance system 71…Display device 72…Buzzer 100…Power supply system

Claims

1. A power supply system mounted on a vehicle, comprising: a first load circuit that operates by power from the main battery and to which a first load is connected; a second load circuit that operates by power from the main battery or an additional battery and to which a second load is connected; a first relay provided in a power supply line that electrically connects the first load and the second load and that conducts or interrupts between the first load circuit and the second load circuit; a second relay that conducts or interrupts between the additional battery and the second load; a controller that determines the state of a start switch for starting the vehicle; wherein the first relay is in an on state when the start switch is off; wherein the second relay is in an off state when the start switch is off; wherein the controller, when determining that the start switch has switched from off to on, turns on the second relay and then turns off the first relay; a power supply system in which the failure diagnosis of the first relay is executed in a state where the first relay is off and the second relay is on.

2. The controller: acquires information regarding the state of the first relay and the state of the second relay; when the second relay is in an off state, does not output a control signal for turning off to the first relay; when the first relay is in an off state, does not output a control signal for turning off to the second relay. The power supply system according to claim 1.

3. The controller maintains the on state of the second relay during execution of the failure diagnosis. The power supply system according to claim 1 or 2.

4. The first load is a load necessary for continuation of the normal operation mode, the second load is a load necessary for continuation of the autonomous driving mode, and the controller, after the failure diagnosis is completed, when determining that the operation mode of the vehicle is the normal operation mode, switches the second relay from on to off. The power supply system according to any one of claims 1 to 3.

5. The controller determines whether the start switch has switched from on to off, and the failure diagnosis is executed after the start switch has switched from on to off. The power supply system according to any one of claims 1 to 4.

6. The controller: determines whether the switching of the start switch from off to on has occurred within a predetermined interval. When it is determined that the switching of the start switch from off to on is performed within a predetermined interval, even if the start switch is switched from off to on, the power supply system according to claim 5 that does not start the failure diagnosis.

7. The first load operates by power from the main battery or the generator, The controller, Before turning on the second relay, by controlling the generator, the circuit voltage of the first load circuit is set to the voltage of the additional battery, The power supply system according to any one of claims 1 to 6, wherein after the circuit voltage of the first load circuit corresponds to the voltage of the additional battery, the second relay is switched from off to on.

8. The power supply system according to claim 7, wherein after the second relay is turned on, the controller controls the generator to set the circuit voltage of the first load circuit to a voltage for the vehicle to travel.

9. The power supply system according to any one of claims 1 to 8, wherein when the controller determines that the first relay is faulty, the controller outputs a command prohibiting the driving mode of the vehicle from being set to the automatic driving mode.

10. A control method for a power supply system mounted on a vehicle, which is executed by a controller, The power supply system is, A first load circuit that operates by power from the main battery and to which a first load is connected, A second load circuit that operates by power from the main battery or an additional battery and to which a second load is connected, A first relay provided in a power supply line that electrically connects the first load and the second load and conducts or cuts off between the first load circuit and the second load circuit, A second relay that conducts or cuts off between the additional battery and the second load, A controller that determines the state of a start switch for starting the vehicle, and is provided with, The first relay is in an on state when the start switch is off, The second relay is in an off state when the start switch is off, A control method for a power supply system, wherein when the controller determines that the start switch has been switched from off to on, after turning on the second relay, the controller turns off the first relay and executes a failure diagnosis of the first relay.

11. The first load is a load necessary for continuing the normal driving mode, The power supply system according to any one of claims 1 to 9, wherein the second load is a load necessary for continuing the automatic driving mode.

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