Power supply system and method for controlling the same

Abstract

To provide a power supply system and a method for controlling the power supply system that prevent the discharge of an additional battery due to a dark current in a load.SOLUTION: A power supply system, which is installed in a vehicle having a normal driving mode by a driver and an autonomous driving mode, comprises a first load circuit, a second load circuit, a first relay, a second relay, and a controller. The first load circuit is connected to a first load, which operates with electric power from a main battery and is required for continuation of the normal driving mode. The second load circuit is connected to a second load, which operates with electric power from the main battery or an additional battery and is required for continuation of the autonomous driving mode. The first relay is provided to a feeder connecting the first and second loads to allow or disallow conduction between the first and second load circuits. The second relay allows or disallows conduction between the additional battery and the second load. The controller determines whether the driving mode of the vehicle is the normal driving mode or the autonomous driving mode.SELECTED DRAWING: Figure 1

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 load's dark current.

[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 load's dark current.

Means for Solving the Problems

[0006] The present invention relates to a power supply system mounted on a vehicle having a normal driving mode by a driver and an automatic driving mode. The power supply system includes a first load circuit that operates by power from a main battery and to which a first load necessary for continuing the normal driving mode is connected, a second load circuit that operates by power from the main battery or an additional battery and to which a second load necessary for continuing the automatic driving mode 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, and a controller that determines whether the driving mode of the vehicle is the normal driving mode or the automatic driving mode, thereby solving the above problems.

Advantages of the Invention

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

Brief Description of the Drawings

[0008]

Figure 1

Figure 2A

Figure 2B

Embodiments 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 the hands-off mode) will be described as an example. In the hands-off mode, the driving support device executes some driving tasks on behalf of the driver, but the driver needs to take back the control of the driving and prepare to drive manually when requested by the driving support device. Also, in the hands-off mode, a redundant function is required to continue autonomous driving 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 required to continue autonomous driving cannot be supplied to the load, and it may 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, the discharge of the additional battery due to the leakage current of the load is prevented by the configuration and method described below, and the power required to continue autonomous driving can be supplied to the load in the automatic driving mode. 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, 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, as shown in FIG. 1. 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 as a main battery conventionally mounted on an engine vehicle. 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 a predetermined remaining battery level or more.

[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, and the like. In a state where the ignition switch 68 of the vehicle is on (hereinafter also referred to as a state where the vehicle is drivable), 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 drivable state of the vehicle indicates a state independent of the vehicle speed 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 idle 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 specified 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 source by the lead battery 11. In other words, the lithium-ion battery 21 is a backup power supply for supplying 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: Battery Management System). 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 causes the power charged in the lithium-ion battery 21 to be output to the second load, discharging 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. Therefore, the capacity of the lithium-ion battery 21 is set to an appropriate capacity such that, for example, the time for continuing to travel 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 maintained 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 and supplies power. Power is supplied to the load actuator 12 included in the first load circuit 1, 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 interruption 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, a normally open type relay is used as the main relay 4. Examples of the main relay 4 include a mechanical relay (also referred to as a mechanical type relay), a semiconductor relay, and the like. The mechanical relay has contacts and mechanically opens and closes the contacts by electromagnetic action to switch on and off. The semiconductor relay is composed of semiconductors and electronic components such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) without contacts, and switches on and off by an electrical signal. In this embodiment, as the main relay 4, a semiconductor relay having a self-cutoff / connection 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 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 to the main relay 4, the maintenance of the on state is released, and the main relay 4 turns on or off again according to the opening / closing control signal. When the main relay 4 is a semiconductor relay as in this 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 state (on) of the main relay 4" represents a state in which the terminals of the main relay 4 are conducting, and "the off state (off) of the main relay 4" represents a state in which the terminals of the main relay 4 are insulated (cut off).

[0027] 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. Examples of the additional relay 5 include a mechanical relay, a semiconductor relay, etc., similar to the main relay 4. In this embodiment, a mechanical relay will be described as an example of the additional relay 5.

[0028] An opening / closing control signal is input to the additional relay 5 from the controller 6, and the additional relay 5 turns on or off according to the input opening / closing control signal. Further, a conduction maintenance command or a release command is input to the additional relay 5 from the controller 6 separately from the opening / closing control signal. Once a conduction maintenance command is input to the additional relay 5, it 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 conduction maintenance command is input to the additional relay 5, the maintenance of the on state is released, and it 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 (interrupted state).

[0029] In addition, in this embodiment, the conduction or interruption of the additional relay 5 by the opening / closing control signal will be described as an example, 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.

[0030] 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: Electronic Control unit) having a memory storing a program and a CPU or the like that executes the program stored in this memory. Note that as an operation circuit, an MPU, a DSP, an ASIC, an FPGA, etc. can be used instead of or together with the CPU. The controller 6 realizes various functions by the CPU executing the program stored in the ROM. The functions realized by the controller 6 will be described later.

[0031] 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.

[0032] 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.

[0033] The automatic driving mode switch 62 is a switch operable 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 automatic driving mode is started when the driver turns on the automatic driving mode switch 62. Also, when the driving mode of the vehicle is the automatic driving mode, the normal driving mode is started when the driver turns off the automatic driving mode switch 62. 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 driving assistance system 70.

[0034] 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 to each component included in the first load circuit 1, for example. The detection result by the first voltage sensor 63 is output to the controller 6. Also, as in this embodiment, when a semiconductor relay having a self-cutoff / connection function is used as the main relay 4, the detection result by the first voltage sensor 63 is also output to the main relay 4.

[0035] 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 to each load included in the second load circuit 2, for example. The detection result by the second voltage sensor 64 is output to the controller 6. Also, as in this embodiment, when a semiconductor relay having a self-cutoff / connection function is used as the main relay 4, the detection result by the second voltage sensor 64 is also output to the main relay 4.

[0036] 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 steering operation by the driver. The information on the steering operation by the driver detected by the torque sensor 67 is output to the controller 6.

[0037] The ignition switch 68 is a start switch (also referred to as 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 the 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 (ON display) for starting the drive source of the vehicle or the display (OFF display) for stopping the drive source of the vehicle, the ignition switch 68 may be provided with a display (ACC display) for energizing an electrical system such as car navigation or audio that has no relation to 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.

[0038] The advanced driving assistance system 70 is a system for assisting a 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 display for notifying the driver that some abnormality has occurred in the automatic driving mode and prompting the driver to perform a driving operation. The buzzer 72 outputs a warning sound for notifying the driver that some abnormality has occurred in the automatic driving mode and prompting the driver to perform a driving operation.

[0039] Next, with reference to FIGS. 2A and 2B, the functions realized by the controller 6 will be described. 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 a state where the ignition switch 68 is off (the parking state of the vehicle).

[0040] 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. When the additional relay 5 and each load included in the second load circuit 2 are conducted in the parking state of the vehicle, the lithium ion battery 21 is discharged by the dark current of the load. By the processing in this step, the connection 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.

[0041] Here, in the flowcharts shown in FIGS. 2A and 2B, the processing of the controller 6 performed before outputting the opening 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 opening control signal to the main relay 4, and when the main relay 4 is in the off state, does not output the opening 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 from being interrupted.

[0042] 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 by the current sensor 61.

[0043] 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.

[0044] 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 controller 6 makes a negative determination, the process proceeds to step S3. If the controller 6 makes an affirmative determination, it 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 processing of the controller 6 is waiting in step S2, since the additional relay 5 is turned off by the processing in 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.

[0045] In step S3, the controller 6 outputs a close control signal to the main relay 4 and an open control signal to the additional relay 5. Note that since the processing for the main relay 4 is the same as in step S1, the controller 6 may not output a close control signal to the main relay 4.

[0046] Also in step S3, when the additional relay 5 is in the off state, the controller 6 may switch the additional relay 5 from off to on at the timing when a vehicle speed equal to or higher than a predetermined speed is detected. For example, when the controller 6 detects from the detection result of the vehicle speed sensor 69 that the vehicle speed of the vehicle has reached a certain number of km / h or more, it may output an open control signal to the additional relay 5 at the detected timing. The predetermined speed is a previously determined speed.

[0047] In step S4, 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, it 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 a load for each load included in the second load circuit 2, it 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, it 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, it 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, the controller 6 determines that the driving mode of the vehicle is the normal driving mode. When it is determined that the driving mode of the vehicle is the automatic driving mode, the process proceeds to step S5, and when it is determined that the driving mode of the vehicle is the normal driving mode, the process proceeds to step S12 shown in FIG. 2B.

[0048] In addition, 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. Further, 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.

[0049] In step S5, the controller 6 outputs a release command to the main relay 4 and outputs a conduction maintenance command to the additional relay 5. As described for the additional relay 5, the conduction maintenance command is a command having a force to maintain the on state. For this reason, for example, even if an opening / closing control signal is input to the additional relay 5 for some reason, if a 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. When the driving mode of the vehicle is determined to be the automatic driving mode, 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 predetermined intervals (for example, every 100 ms). Thereby, in the automatic 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 controllable by the 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 the release command.

[0050] In step S6, 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 of 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 of 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 S7. 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 S8.

[0051] In step S7, the controller 6 outputs a closed control signal to the main relay 4 and the additional relay 5. In the example of FIG. 2A, step S7 is described for comparison with step S8. However, due to the processing in step S1 or step S3, the main relay 4 is on, and due to the processing in step S5, the additional relay 5 is on. Therefore, the controller 6 may omit the processing in step S7. When the processing in step S7 ends, the process returns to step S4, and again, the driving mode of the vehicle is determined. In a state where the vehicle can travel in the automatic driving mode, if no voltage abnormality occurs in the power supply system 100, the processing from step S4 to step S7 is repeatedly executed, so both the main relay 4 and the additional relay 5 maintain the on state.

[0052] If an affirmative determination is made in step S6, the process proceeds to step S8. In step S8, the controller 6 outputs an open control signal to the main relay 4 and a closed 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 the predetermined voltage range in the automatic driving mode. On the other hand, in the automatic 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 S5. 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 automatic driving mode, each load included in the second load circuit 2 can continue to operate by 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 S5, the controller 6 may not output a closed control signal to the additional relay 5.

[0053] 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.

[0054] In step S9, the controller 6 outputs a warning display signal to the display device 71 in order to notify the driver that an abnormality has occurred in the automatic driving mode. The controller 6 may also 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 also output a warning sound signal to the buzzer 72. By the processing in this step, the driver is urged 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 that has been performed by the driving support device. Since the additional relay 5 maintains the on state by the processing in step S5, 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.

[0055] 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 S10, 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 obtains a signal of the driver's braking operation from the brake switch 66, or obtains a signal of the driver's steering operation 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.

[0056] In step S11, the controller 6 outputs a closing control signal to the main relay 4 and the additional relay 5. Due to the conduction maintenance command being input to the additional relay 5 by the process of step S5, the controller 6 may not need to output the closing control signal to the additional relay 5. Also, the controller 6 may output a cancellation command for the conduction maintenance command output in step S5 to the additional relay 5. When the process in step S11 ends, the controller 6 ends the processes shown in FIGS. 2A and 2B.

[0057] In step S4, when it is determined that the driving mode of the vehicle is the normal driving mode, the process proceeds to step S12 shown in FIG. 2B. In step S12, 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, the controller 6 outputs a conduction maintenance command to the main relay 4 at a predetermined cycle (for example, every 100 ms) until a release command is output to the main relay 4. 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-shutdown / connection function as in the present embodiment, by this step, the self-shutdown / 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-shutdown / 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.

[0058] In step S13, 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 S13 is a step corresponding to step S6, the description of step S6 is incorporated for the description of step S13. 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 S14.

[0059] If a negative determination is made in step S13, the process returns to step S4, and the driving mode of the vehicle is determined again. When the vehicle is in a drivable state in the normal driving mode and no voltage abnormality occurs in the power supply system 100, the processes of step S4, step S12, and step S13 are repeatedly executed, so both the main relay 4 and the additional relay 5 maintain the on state. During the repeated execution of the processes of step S4, step S12, and step S13, if the ignition switch 68 is turned off, the controller 6 determines that the vehicle has shifted from a drivable state 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.

[0060] Here, the state of the power supply system 100 that may occur when the additional relay 5 switches 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 will be described. For example, when the processes of step S4, step S12, and step S13 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 switches 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 switch from on to off due to the self-cutoff / connection function when detecting the surge voltage. However, since the self-cutoff / connection function of the main relay 4 is invalidated by the process in step S12 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 switching 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.

[0061] Returning to FIG. 2B, if an affirmative determination is made in step S13, the process proceeds to step S14. In step S14, the controller 6 outputs a close 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 its 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 S12. As described above, since the main relay 4 is in the 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 even in this step, but the main relay 4 maintains its on state by the processing in step S12. Note that since a conduction maintenance command has been input to the main relay 4 by the processing in step S12, the controller 6 may not output a close control signal to the main relay 4.

[0062] In step S15, the controller 6 determines whether or not the voltage abnormality that occurred in step S13 continues based on the circuit voltage of the second load circuit 2. Since step S15 corresponds to the steps corresponding to step S6 and step S13, the descriptions of step S6 and step S13 are incorporated for the description of step S15. 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 S11 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 S15 until an affirmative determination is made.

[0063] While waiting in step S15, if the ignition switch 68 is turned off, the controller 6 determines that the vehicle has shifted from a drivable state 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. Further, the controller 6 may output a release command for the conduction maintenance command output in step S12 to the main relay 4.

[0064] If a negative determination is made in step S15, the process proceeds to step S11 shown in FIG. 2A. In step S11, 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 S12, 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 S12 to the main relay 4. When the process in step S11 is completed, the controller 6 ends the processes shown in FIGS. 2A and 2B.

[0065] Note that when the process proceeds from step S15 to step S11 and then the ignition switch 68 is turned off, the controller 6 determines that the vehicle has shifted from a drivable state 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. Further, the controller 6 may output a release command for the conduction maintenance command output in step S12 to the main relay 4.

[0066] 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 driving mode and an autonomous driving 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 driving 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 autonomous driving 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, when the controller 6 determines that the driving mode of the vehicle is the normal driving mode (determined as the normal driving mode in step S4 of FIG. 2A), when the circuit voltage of the second load circuit 2 goes out of the predetermined voltage range (YES in step S13 of FIG. 2B), the additional relay 5 is switched from on to off (step S14 of FIG. 2B). On the other hand, when the controller 6 determines that the driving mode of the vehicle is the autonomous driving mode (determined as the autonomous driving mode in step S4 of FIG. 2A), regardless of the circuit voltage of the second load circuit 2, the on state of the additional relay 5 is maintained (steps S7 and S8 of FIG. 2A).

[0067] Since the additional relay 5 can cut off the connection 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 standby current of the load and the remaining battery level of the lithium-ion battery 21 from decreasing. As a result, even if a situation occurs in which the main relay 4 is turned off while the vehicle is in a state where it can travel in the autonomous driving mode, the lithium-ion battery 21 can supply power to each load included in the second load circuit 2 to continue autonomous driving. Also, it is possible to prevent the so-called over-discharge of the lithium-ion battery 21, in which the lithium-ion battery 21 continues to discharge in a state where the voltage has dropped below the end-of-discharge voltage. As a result, deterioration of the lithium-ion battery 21 can be alleviated, and the battery life of the lithium-ion battery 21 can be extended. Also, by providing the additional relay 5, there is a concern that in the autonomous driving mode, the additional relay 5 may suddenly turn off for some reason, cutting off the connection between the lithium-ion battery 21, which is a backup power supply, and each load included in the second load circuit 2. However, in the power supply system 100 and the control method of the power supply system 100 of the present embodiment, in the autonomous driving mode, since the additional relay 5 maintains the on state, it is possible to prevent the connection between the lithium-ion battery 21 and each load included in the second load circuit 2 from being cut off. 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 remaining battery level of the lithium-ion battery 21 from decreasing due to standby current discharge and ensure the backup operation by the lithium-ion battery 21.

[0068] Also, in the present embodiment, when the controller 6 determines that the driving mode of the vehicle is the autonomous driving mode (determined to be the autonomous driving mode in step S4 of FIG. 2A), the controller 6 outputs a conduction maintenance command for maintaining the on state to the additional relay 5 (step S5 of FIG. 2A). As a result, in the autonomous driving mode, since the on state of the additional relay 5 can be maintained, the connection between the lithium-ion battery 21 and the second load circuit 2 is maintained in a conductive state. As a result, even if a situation occurs in which the main relay 4 is turned off in the autonomous driving mode, each load included in the second load circuit 2 can continue the autonomous driving of the vehicle.

[0069] Also, in the present embodiment, the conduction maintenance command output to the additional relay 5 is a command to maintain the ON state of the additional relay 5 regardless of the circuit voltage of the second load circuit 2 and the switching of the main relay 4 from ON to OFF (step S5 in FIG. 2A). Thereby, even if a signal corresponding to the open control signal is input to the additional relay 5 due to the circuit voltage of the second load circuit 2 or the switching of the main relay 4 from ON to OFF, the ON state of the additional relay 5 can be maintained.

[0070] Also, in the present embodiment, when the controller 6 determines that the driving mode of the vehicle is the normal driving mode (determined to be the normal driving mode in step S4 of FIG. 2A), the controller 6 outputs a release command for releasing the conduction maintenance command to the additional relay 5 (step S12 in FIG. 2B). Thereby, in the normal driving mode, the ON and OFF of the additional relay 5 can be controlled by the open / close control signal. As a result, as in the present embodiment, the controller 6 can turn off the additional relay 5 when it is determined that the circuit voltage of the second load circuit 2 is outside the predetermined voltage range in the normal driving mode (step S14 in FIG. 2B).

[0071] 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 the open control signal to the main relay 4. When the main relay 4 is in the OFF state, the controller 6 does not output the 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, without requiring complicated processing, by only monitoring the state of the main relay 4 and the state of the additional relay 5, it is possible to prevent the power supply to the second load circuit 2 side from being cut off, and thus the arithmetic load of the controller 6 can be reduced and the processing speed can be improved.

[0072] Also, in this embodiment, the controller 6 determines whether the vehicle is in a parked state. When it is determined that the vehicle is in a parked state, the additional relay 5 is turned off. As a result, in the parked state of the vehicle, since the connection between the lithium-ion battery 21 and each load included in the second load circuit 2 is interrupted, it is possible to prevent the lithium-ion battery 21 from being discharged by the leakage current of the load. Since it is possible to prevent the reduction of the remaining battery level of the lithium-ion battery 21 due to the leakage current discharge, each load included in the second load circuit 2 can operate as specified by the power from the lithium-ion battery 21. Also, the output voltage of the lithium-ion battery 21 can be maintained at a voltage for each load to operate as specified.

[0073] Also, in this embodiment, when the additional relay 5 is in the off state, the controller 6 switches the additional relay 5 from off to on at the timing when a vehicle speed equal to or higher than a predetermined speed is detected (step S3 in FIG. 2A). Thereby, for example, in accordance with the start timing of the vehicle, the lithium-ion battery 21 and each load included in the second load circuit 2 can be connected.

[0074] Also, in this embodiment, the main relay 4 is a normally open type relay, and the additional relay 5 is a normally closed type relay. Thereby, before the main relay 4 is electrically connected to the lead battery 11 or the alternator 14 during vehicle manufacture or the like, the main relay 4 can be turned off in advance. Similarly, before the additional relay 5 is electrically connected to the lithium-ion battery 21, the additional relay 5 can be turned on in advance. The state of each relay can be controlled in advance without requiring an opening / closing control signal.

[0075] Note that the embodiments described above are described to facilitate the understanding of the present invention, and are not described 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.

[0076] In the above-described embodiment, in the flowchart of FIG. 2A, when proceeding to step S11 through steps S8 to S10, the additional relay 5 maintains the on state, but the controller 6 may turn off the additional relay 5 according to the remaining battery level of the lithium-ion battery 21. When the controller 6 determines that the driving mode of the vehicle is the autonomous driving mode, if the circuit voltage of the second load circuit 2 is outside the predetermined voltage range, the main relay 4 is switched from on to off (step S8 in FIG. 2A). After the driving mode of the vehicle shifts from the autonomous driving mode to the normal driving mode (step S10 in FIG. 2A), if the remaining battery level of the lithium-ion battery 21 is equal to or less than the predetermined remaining level, the additional relay 5 may be switched from on to off. For the calculation of the remaining battery level of the lithium-ion battery 21 performed by the controller 6, a known calculation method known at the time of filing this application can be used. Since over-discharge of the lithium-ion battery 21 can be prevented, deterioration of the lithium-ion battery 21 can be mitigated, and the battery life of the lithium-ion battery 21 can be extended.

[0077] 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. Further, 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, as the generator of the first load circuit, a generator, a motor generator, or the like may be used. Additionally, 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 autonomous driving mode may be changed according to the specifications of the vehicle and the driving support device. Moreover, 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. Also, in the above-described embodiment, the case where a semiconductor relay having a self-cutoff / connection function is used as the main relay 4 is shown. However, as the main relay 4, a semiconductor relay without a self-cutoff / connection function or a mechanical relay may be used. Further, in the above-described embodiment, the case where a mechanical relay is used as the additional relay 5 is shown. However, as the additional relay 5, a semiconductor relay may be used.

[0078] Also, in the above-described embodiment, the power supply system and the control method of the power supply system according to the present invention were described by taking as an example the case of applying them 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.

[0079] In the above-described embodiment, the power supply system and the control method of the power supply system according to the present invention were 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 the 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 operation mode of the vehicle can be applied to a vehicle equipped with a power supply system.

[0080] In the above-described embodiment, the control procedure of proceeding to step S11 after the operation mode of the vehicle shifts from the automatic operation mode to the normal operation mode in step S10 of FIG. 2A was described by taking as an example. However, after the process of step S10, it may proceed to step S12 shown in FIG. 2B in the same manner as when the operation mode of the vehicle is determined to be the normal operation mode in step S4.

[0081] In the above-described embodiment, the case where it is determined whether or not the circuit voltage of the second load circuit 2 is outside a predetermined voltage range in step S6 of FIG. 2A, steps S13 and S15 of FIG. 2B has been described. However, since the first load circuit 1 and the second load circuit 2 are conducted by the main relay 4 in any step, in each step, the controller 6 may determine whether or not 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 S13 of FIG. 2B has been described. However, in the normal operation 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 operation mode of the vehicle is the normal operation mode (determined as the normal operation mode in step S4 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 being 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 operation 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 alleviated.

[0082] In the above-described embodiment, as an example of the condition for the controller 6 to turn off the main relay 4 in step S6 of FIG. 2A, the condition that the circuit voltage of the second load circuit 2 is outside a predetermined voltage range has been described. However, in step S6, 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 S13 of FIG. 2B, the condition that the circuit voltage of the second load circuit 2 is outside a predetermined voltage range has been described. However, in step S13, 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.

Explanation of Signs

[0083] 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 having a normal driving mode by a driver and an autonomous driving mode, comprising: a first load circuit that operates by power from a main battery and to which a first load necessary for continuation of the normal driving mode is connected; a second load circuit that operates by power from the main battery or an additional battery and to which a second load necessary for continuation of the autonomous driving mode 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 driving mode of the vehicle; and wherein the controller: when determining that the driving mode is the normal driving mode, switches the second relay from on to off when the circuit voltage of the second load circuit is outside a predetermined voltage range; when determining that the driving mode is the autonomous driving mode, maintains the on state of the second relay regardless of the circuit voltage of the second load circuit.

2. The power supply system according to claim 1, wherein the controller outputs a first command for maintaining the on state to the second relay when determining that the driving mode is the autonomous driving mode.

3. The power supply system according to claim 2, wherein the first command is a command for maintaining the on state of the second relay regardless of the circuit voltage of the second load circuit and the switching of the first relay from on to off.

4. The power supply system according to claim 2 or 3, wherein the controller outputs a second command for canceling the first command to the second relay when determining that the driving mode is the normal driving mode.

5. 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 it off to the first relay; when the first relay is in an off state, does not output a control signal for turning it off to the second relay.

6. The controller: determines whether or not the vehicle is in a parked state; when determining that the vehicle is in a parked state, turns off the second relay.

7. The power supply system according to any one of claims 1 to 6, wherein when the second relay is in an off state, the controller switches the second relay from off to on at the timing when the vehicle speed of the vehicle is detected to be equal to or higher than a predetermined speed.

8. The controller When it is determined that the driving mode is the automatic driving mode, if the circuit voltage of the second load circuit is outside the predetermined voltage range, the first relay is switched from on to off. The power supply system according to any one of claims 1 to 7, wherein after the driving mode shifts from the automatic driving mode to the normal driving mode, if the remaining battery level of the additional battery becomes equal to or lower than a predetermined value, the second relay is turned off.

9. The first relay is a normally open type relay, The power supply system according to any one of claims 1 to 8, wherein the second relay is a normally closed type relay.

10. A control method for a power supply system mounted on a vehicle having a normal driving mode by a driver and an automatic driving mode, which is executed by a controller, The power supply system includes A first load circuit that operates with power from the main battery and to which a first load necessary for continuing the normal driving mode is connected; A second load circuit that operates with power from the main battery or the additional battery and to which a second load necessary for continuing the automatic driving mode 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; And a controller that determines the driving mode of the vehicle. The controller When it is determined that the driving mode is the normal driving mode, if the circuit voltage of the second load circuit is outside the predetermined voltage range, the second relay is switched from on to off. A control method for a power supply system, wherein when it is determined that the driving mode is the automatic driving mode, the on state of the second relay is maintained regardless of the circuit voltage of the second load circuit.

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