JP7697359B2 - Power supply system and method for controlling the power supply system - Google Patents

Description

The present invention relates to a power supply system and a method for controlling a power supply system.

A method for controlling the power supply of an autonomous vehicle having a circuit interrupting mechanism between a first load circuit powered by the main battery and a second load circuit powered by an additional battery is known (Patent Document 1). A load required for the driver to continue normal driving mode is connected to the first load circuit, and an autonomous driving function load that is required for the autonomous driving mode to continue and requires voltage maintenance is connected to the second load circuit. In this method for controlling the power supply of an autonomous vehicle, when the circuit interrupting mechanism is connected and it is determined that power will be drawn from the additional battery to the first load circuit based on the load state detected on the second load circuit side, the circuit interrupting mechanism is cut off.

JP 2017-177857 A

The method for controlling the power supply of an autonomous vehicle described in Patent Document 1 has the problem that the additional battery is discharged due to the dark current of the load because the additional battery cannot be disconnected from the load.

The problem that the present invention aims to solve is to provide a power supply system and a control method for the power supply system that prevent discharge of the additional battery due to the dark current of the load.

The present invention solves the above problems by providing a power supply system mounted on a vehicle having a normal driving mode and an automatic driving mode, the power supply system including a first load circuit that operates on power from the main battery and is connected to a first load necessary for continuing the normal driving mode, a second load circuit that operates on power from the main battery or an additional battery and is connected to a second load necessary for continuing the automatic driving mode, a first relay that is provided in a power supply line that electrically connects the first load and the second load and that connects or disconnects the first load circuit and the second load circuit, a second relay that connects or disconnects the second load and the additional battery, and a controller that determines whether the vehicle is in the normal driving mode or the automatic driving mode.

According to the present invention, the second relay can disconnect the additional battery from the load, thereby preventing the additional battery from discharging due to the dark current of the load.

FIG. 1 is a schematic diagram of a power supply system according to the present embodiment. FIG. 2A is a flowchart showing an example of the procedure of a control method for a power supply system executed by the controller shown in FIG. FIG. 2B is a flowchart showing an example of the procedure of a control method for the power supply system executed by the controller shown in FIG.

The following describes an embodiment of a power supply system and a method for controlling a power supply system according to the present invention with reference to the drawings.

Figure 1 is a schematic diagram of a power supply system 100 according to this embodiment. In this embodiment, a vehicle equipped with the power supply system 100 will be described as an example in which the driving source is an engine and the vehicle has an autonomous driving control function. A vehicle equipped with an autonomous driving control function has a normal driving mode and an autonomous driving mode as driving modes. When set to the normal driving mode, the vehicle runs according to driving operations (steering, accelerator, brake, etc.) performed by the driver. On the other hand, when set to the autonomous driving mode, the vehicle runs according to driving operations performed by a driving assistance device (not shown) in addition to the driver.

In the autonomous driving mode, the content of the driving assistance realized by the autonomous driving control function may differ depending on the driving assistance level. The driving assistance level is a level indicating the degree of intervention when the driving assistance device assists the driving of the vehicle by the autonomous driving control function. The higher the driving assistance level, the lower the contribution of the driver to the driving of the vehicle. Specifically, the driving assistance level can be set using a definition based on SAE J3016 of the Society of Automotive Engineers (SAE). In this embodiment, the driving assistance level realized by the driving assistance device is described as driving assistance level 2. Furthermore, in this embodiment, a vehicle having a mode (also called a hands-off mode) in which the vehicle runs autonomously without the driver touching the steering wheel is described as an example. In the hands-off mode, the driving assistance device executes some driving tasks on behalf of the driver, but the driver needs to regain control of the driving and prepare to drive manually when requested by the driving assistance device. In addition, in the hands-off mode, a redundant function is required to continue autonomous driving until the driver performs driving operation in response to a request from the driving assistance device. As an example of a redundant function, for example, a vehicle with an autonomous 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.

However, mounting an additional battery also poses the problem that the additional battery is discharged by the dark current of the load connected to the additional battery while the vehicle ignition switch is off. If the additional battery discharges due to the dark current of the load, the remaining battery charge of the additional battery decreases, and in the autonomous driving mode, the additional battery may not be able to supply the load with the power required for continuing autonomous driving, and may not function as a backup power supply source. In the power supply system and power supply system control method according to the present invention, the configuration and method described below prevent the additional battery from being discharged due to the dark current of the load, and in the autonomous driving mode, the load can be supplied with the power required for continuing autonomous driving. In the following, the driving assistance device described above will be described as a configuration included in an advanced driver assistance system (ADAS: Advanced Driver Assistance System).

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.

The first load circuit 1 is a load circuit that operates using power from a lead battery 11 (main battery) or an alternator 14, and to which a first load necessary for continuing the above-mentioned normal operation mode is connected. In this embodiment, as shown in FIG. 1, the first load circuit 1 includes a lead battery 11 connected to a 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 operation mode include the load actuator 12 and the starter motor 13.

The lead battery 11 is a secondary battery that has traditionally been installed in engine vehicles as a main battery. The lead battery 11 is charged by an alternator 14, which acts as a generator, so that the remaining battery charge does not decrease. The alternator 14 generates electricity using a rotary drive mechanism (not shown) driven by the engine, and charges the lead battery 11 so that the remaining battery charge is maintained at or above a predetermined remaining battery charge.

The load actuator 12 is an auxiliary device that operates using power from the lead battery 11 or 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. When the vehicle's ignition switch 68 is turned on (hereinafter also referred to as the vehicle's runnable state), the load actuator 12 is supplied with power stored in the lead battery 11 or power generated by the alternator 14. On the other hand, when the vehicle's ignition switch 68 is turned off (hereinafter also referred to as the vehicle's parked state), the load actuator 12 is supplied with power stored in the lead battery 11. The runnable state of the vehicle indicates a state that is unrelated to the vehicle speed, and includes a state in which the vehicle is running and a state in which the vehicle is stopped.

The starter motor 13 is a motor for starting the engine when the vehicle starts and restarts the engine when the vehicle is stopped at idle.

The second load circuit 2 is a load circuit that operates using power from the lead battery 11 or the lithium ion battery 21 (additional battery) and is connected to a second load necessary for continuing the above-mentioned autonomous driving mode. In this 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 autonomous 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 continue operating the actuators according to the specifications, it is necessary to maintain the input voltage to each actuator within the input voltage range determined by the specifications.

The lithium ion battery 21 is a secondary battery added as a new power source to the lead battery 11 to continue the autonomous driving control function of the vehicle. In other words, the lithium ion battery 21 is a backup power supply source that supplies power to each load included in the second load circuit 2 to continue autonomous driving in the autonomous driving mode. 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, the lithium ion battery 21 and the first load circuit 1 are conductive, so that 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 autonomous driving mode, the main relay 4 is switched from on to off when the circuit voltage of the second load circuit 2 falls outside a predetermined voltage range. However, since the additional relay 5 remains on, a conductive state 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, discharging the lithium ion battery 21. Once the main relay 4 switches from on to off in the autonomous driving mode, the main relay 4 remains off until the autonomous driving mode switches to the normal driving mode, so that 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 the time during which the vehicle continues to drive in the autonomous driving mode is at least equal to or longer than the required time.

The lithium ion battery 21 also has a characteristic that its internal resistance is smaller than that of the lead battery 11. Therefore, for example, even if the EPS actuator 22 is activated and consumes a large current, the voltage can be maintained high.

The EPS actuator 22 is an EPS motor that generates an electric assist force, and is a load that must operate in the autonomous 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 reduce steering effort. Here, "EPS" is an abbreviation for "Electric Power Steering."

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

The ADAS actuator 24 is an actuator that performs various driving operation assistance functions to assist the driver in driving operations, and is a load that must operate in the autonomous driving mode. The ADAS actuator 24 is used in the advanced driver assistance system 70.

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 via the power supply line 3 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.

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, a normally open type relay is used as the main relay 4. Examples of the main relay 4 include a mechanical relay (also called a mechanical relay) and a semiconductor relay. A mechanical relay has contacts and mechanically opens and closes the contacts by electromagnetic action to switch on and off. A semiconductor relay does not have contacts and is composed of semiconductors and electronic components such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), and switches on and off by an electric signal. In this embodiment, a semiconductor relay having a self-interrupting/connecting function that autonomously switches on and off for overvoltage protection and overcurrent protection will be described as an example of the main relay 4.

A switching 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 switching control signal. In addition to the switching control signal, a continuity maintenance command or a release command is input from the controller 6 to the main relay 4. Once a continuity maintenance command is input to the main relay 4, the main relay 4 continues to maintain the on state until a release command is input, regardless of whether or not a switching control signal is input. When a release command is input after a continuity maintenance command is input, the main relay 4 releases the maintenance of the on state and turns on or off again according to the switching control signal. In the case where the main relay 4 is a semiconductor relay as in this embodiment, the switching 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 continuity maintenance command is, for example, a signal for disabling the self-shutdown/connection function and maintaining the on state in order to prevent the self-shutdown/connection function from switching from on to off. The release command is, for example, a signal for enabling the self-shutdown/connection function. An example of the self-shutoff/connection function is a protection function that switches 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 in the specifications of the main relay 4. An example of the self-shutoff/connection function is a protection function that switches the main relay 4 from on to off when the current flowing through the main relay 4 (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 in the specifications of the main relay 4. In the following description, "on (on state) of the main relay 4" refers to a state in which the terminals of the main relay 4 are conductive, and "off (off state) of the main relay 4" refers to a state in which the terminals of the main relay 4 are insulated (cut off).

The additional relay 5 is electrically connected to the power supply line 3 on the second load circuit 2 side, and is a battery interrupting mechanism for establishing or interrupting electrical continuity 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 a current sensor 61. In this embodiment, a normally closed type relay is used as the additional relay 5. As with the main relay 4, examples of the additional relay 5 include a mechanical relay and a semiconductor relay. In this embodiment, a mechanical relay will be used as an example of the additional relay 5.

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 continuity maintenance command or a release command is input from the controller 6 to the additional relay 5. Once a continuity maintenance command is input to the additional relay 5, the additional relay 5 continues to maintain the on state until a release command is input, regardless of whether or not the opening/closing control signal is input. When a release command is input after the continuity maintenance command is input, the additional relay 5 releases the maintenance of the on state and turns on or off again according to the opening/closing control signal. In the case where 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, or a voltage stop signal for eliminating the magnetic field to switch from on to off. In addition, the continuity maintenance command is, for example, a forced voltage application signal for continuing to generate a magnetic field and maintaining the on state. In the following explanation, "additional relay 5 on (on state)" refers to a state in which the terminals of additional relay 5 are conductive, and "additional relay 5 off (off state)" refers to a state in which the terminals of additional relay 5 are insulated (cut off).

In addition, in this embodiment, the conduction or interruption of the additional relay 5 by the opening/closing control signal is 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, the power supply system may be configured such that a DCDC converter is provided between the lithium ion battery 21 and the additional relay 5, and the voltage of the lithium ion battery 21 is boosted by the DCDC converter and output. In 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.

Next, the controller 6 will be described. The controller 6 is an electronic control unit (ECU) that is configured by a computer equipped with hardware and software, and has a memory that stores programs and a CPU that executes the programs stored in the memory. Note that as the operating circuit, an MPU, DSP, ASIC, FPGA, etc. can be used instead of or in addition to 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.

As shown in FIG. 1, various information is 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. The controller 6 also executes processing based on the input information, and outputs an opening/closing control signal, a continuity maintenance command, or a release command to the main relay 4 and/or the additional relay 5 based on the execution result. The controller 6 also executes processing based on the input information, and outputs a control command to a display device 71 and a buzzer 72 based on the execution result.

The current sensor 61 is provided between the main relay 4 and the additional relay 5, and detects the direction of the current to the lithium-ion battery 21. The detection result by the current sensor 61 is output to the controller 6.

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

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. Furthermore, when a semiconductor relay having a self-interrupting/connecting 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.

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. Furthermore, when a semiconductor relay having a self-interrupting/connecting 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.

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 braking operation by the driver. Information on the braking 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 due to the steering operation by the driver. Information on the steering operation by the driver detected by the torque sensor 67 is output to the controller 6.

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 driving source is an engine as in this embodiment, when the ignition switch 68 is turned on, the engine starts and the vehicle is ready to run. On the other hand, when the ignition switch 68 is turned off, the engine stops and the vehicle is parked. The ignition switch 68 can be, for example, an engine key type in which the vehicle is started by the occupant turning the vehicle key inserted in the keyhole, or a push start type in which the vehicle is started by the occupant pressing a button. In addition to an indication (ON indication) for starting the driving source of the vehicle or an indication (OFF indication) for stopping the driving source of the vehicle, the ignition switch 68 may also be provided with an indication (ACC indication) for energizing electrical systems such as car navigation and audio that are not related to the running of the vehicle, an indication (START indication) for driving the starter motor 13 to start the air conditioning system, and the like. 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. The detection result by the vehicle speed sensor 69 is output to the controller 6.

The advanced driving assistance system 70 is a system that performs automatic brake control, auto-cruise control, lane keeping control, etc., and assists the driver in driving. The processing results of the advanced driving assistance system 70 are output to the controller 6. The display device 71 displays a warning display to inform the driver that some abnormality has occurred in the autonomous driving mode, and to urge the driver to perform driving operations. The buzzer 72 outputs a warning sound to inform the driver that some abnormality has occurred in the autonomous driving mode, and to urge the driver to perform driving operations.

Next, the functions realized by the controller 6 will be described with reference to Figures 2A and 2B. Figures 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 Figure 1. The procedure of this control method starts with the ignition switch 68 in an OFF state (the vehicle is in a parked state).

In step S1, the controller 6 outputs a close control signal (hereinafter simply referred to as a close control signal) to the main relay 4 to turn on the relay, and outputs an open control signal (hereinafter simply referred to as an open control signal) to turn off the relay to the additional relay 5. When the vehicle is parked, and electrical continuity is established 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. The processing in this step cuts off electrical continuity between the additional relay 5 and each load included in the second load circuit 2, thereby preventing the lithium ion battery 21 from being discharged by the dark current of the load.

2A and 2B, the process 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 this embodiment, the controller 6 controls the opening and closing 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 on the state of the main relay 4 and the state of the additional relay 5, and when the additional relay 5 is in the off state, it does not output the open control signal to the main relay 4, and when the main relay 4 is in the off state, it does not output the open control signal to the additional relay 5. This process is to prevent the main relay 4 and the additional relay 5 from both being turned off, causing a cutoff in the power supply to each load included in the second load circuit.

The information regarding the state of the main relay 4 and the additional relay 5 includes, for example, the detection result of the current sensor 61, and the controller 6 determines the state of the main relay 4 and the additional relay 5 from the detection result of the current sensor 61.

For example, when the current direction detected by the current sensor 61 (hereinafter referred to as the detected current direction) is the direction toward 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. The controller 6 may also determine that both the main relay 4 and the additional relay 5 are in the ON state when the detected current direction is from the lithium ion battery 21 to the first load circuit 1. The controller 6 determines that the main relay 4 is in the OFF state and the additional relay 5 is in the ON state when the detected current direction is from the lithium ion battery 21 to each load included in the second load circuit 2. The controller 6 determines that at least the additional relay 5 is in the OFF state when the detected current direction is not in either direction. Note that the determination method using the detection result of the current sensor 61 is merely an example. For example, when signals indicating an ON state or an OFF state can be acquired 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 acquired from the main relay 4 and the additional relay 5. In the explanation of the following 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 executes the above-mentioned processing before outputting the open control signal.

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 receives an ON signal from the ignition switch 68 indicating that the drive source of the vehicle is activated, the controller 6 determines that the vehicle is not in a parked state, assuming that the vehicle has transitioned from a parked state to a runnable state. On the other hand, when the controller 6 receives an OFF signal from the ignition switch 68 indicating that the drive source of the vehicle is stopped, the controller 6 determines that the vehicle is in a parked state. When the controller 6 makes a negative determination, the controller 6 proceeds to step S3. When the controller 6 makes a positive determination, the controller 6 waits in step S2 until a negative determination is made, that is, until the ignition switch 68 is turned on and the vehicle is in a runnable state. While the controller 6 is waiting in step S2, the additional relay 5 is turned off by the process of step S1, so that the discharge of the lithium ion battery 21 due to the dark current of the load can be prevented. The method for determining whether the vehicle is in a parked state is not limited to a method based on operation information from the ignition switch 68, but may be any other method known at the time of filing of this application.

In step S3, the controller 6 outputs a close control signal to the main relay 4 and outputs 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 does not need to output a close control signal to the main relay 4.

In addition, in step S3, if 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 it detects that the vehicle speed is equal to or greater than a predetermined speed. For example, if the controller 6 detects that the vehicle speed is equal to or greater than several km/h based on the detection result from the vehicle speed sensor 69, it may output an open control signal to the additional relay 5 at the detection timing. The predetermined speed is a speed that is set in advance.

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, the controller 6 may determine that the driving mode of the vehicle is the automatic driving mode when it acquires an on signal from the automatic driving mode switch 62. The controller 6 may also determine that the driving mode of the vehicle is the automatic driving mode when it detects the output of a control signal for operating each load included in the second load circuit 2. The controller 6 may also determine that the driving mode of the vehicle is the automatic driving mode when it acquires a signal indicating that each load included in the second load circuit 2 is operating. The controller 6 determines that the driving mode of the vehicle is the automatic driving mode when any one of the above examples applies. On the other hand, the controller 6 determines that the driving mode of the vehicle is the normal driving mode when none of the above examples applies. 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.

Although the method of determining that the driving mode of the vehicle is the normal driving mode has been described as an example of a method of determining that the driving mode of the vehicle is not the automatic driving mode, the driving mode of the vehicle may be determined to be the normal driving mode by another method. For example, the controller 6 may determine that the driving mode of the vehicle is the normal driving mode when an off signal is acquired from the automatic driving mode switch 62. The controller 6 may also determine that the driving mode of the vehicle is the normal driving mode when a signal of a brake operation by the driver is acquired from the brake switch 66. The controller 6 may also determine that the driving mode of the vehicle is the normal driving mode when a signal of a steering operation by the driver is acquired from the torque sensor 67. The controller 6 may determine that the driving mode of the vehicle is the normal driving mode when any one of the above examples applies. The controller 6 may also obtain 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 receives an on signal from the autonomous driving mode switch 62, it determines that the driving mode of the vehicle is the autonomous driving mode. When the advanced driving assistance system 70 receives an off signal from the autonomous driving mode switch 62, it determines that the driving mode of the vehicle is the normal driving mode. The controller 6 may determine whether the driving mode of the vehicle is the autonomous driving mode or the normal driving mode according to the driving mode signal received from the advanced driving assistance system 70.

In step S5, the controller 6 outputs a release command to the main relay 4 and outputs a continuity maintenance command to the additional relay 5. As explained in the additional relay 5, the continuity maintenance command is a command that has a compulsory 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 continuity 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 continuity maintenance command. If the driving mode of the vehicle is determined to be the automatic driving mode, in this step, the controller 6 keeps the additional relay 5 in the on state. In addition, the controller 6 outputs a continuity maintenance command to the additional relay 5 at predetermined intervals (for example, every 100 ms) until the release command is output to the additional relay 5. This can further reduce the possibility that the additional relay 5 is turned off in the automatic driving mode. On the other hand, the controller 6 outputs a release command to the main relay 4 to make the main relay 4 controllable by the opening/closing control signal. In the present embodiment, when the main relay 4 is a semiconductor relay with a self-shutoff/connection function, the self-shutoff/connection function of the main relay 4 is enabled by a release command.

In step S6, the controller 6 determines whether or not a voltage abnormality has occurred in the power supply system 100 based on the circuit voltage of the second load circuit 2. Based on the detection result of the second voltage sensor 64, the controller 6 determines whether or not the circuit voltage on the additional battery side (circuit voltage of the second load circuit 2) is outside a predetermined voltage range. The predetermined voltage range is a range in units of voltage, and is a range that has been determined in advance. The upper limit 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 of the predetermined range is a voltage value determined to operate each load included in the second load circuit 2 according to specifications. If the controller 6 makes a negative determination, that is, if 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, if the controller 6 makes a positive determination, that is, if it is determined that a voltage abnormality has occurred in the power supply system 100, the process proceeds to step S8.

In step S7, 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 S7 is described for comparison with step S8. However, since the main relay 4 is turned on by the processing of step S1 or step S3, and the additional relay 5 is turned on by the processing of step S5, the controller 6 may omit the processing of step S7. When the processing of step S7 ends, the process returns to step S4, and the driving mode of the vehicle is determined again. When the vehicle is in a state in which it can run in the autonomous driving mode and no voltage abnormality occurs in the power supply system 100, the processing of steps S4 to S7 is repeatedly executed, so that both the main relay 4 and the additional relay 5 remain on.

If the determination in step S6 is affirmative, the process proceeds to step S8. In step S8, the controller 6 outputs an open control signal to the main relay 4 and outputs a close control signal to the additional relay 5. In the automatic driving mode, when the circuit voltage of the second load circuit 2 falls outside a predetermined voltage range, the main relay 4 is switched from on to off. On the other hand, in the automatic driving mode, the additional relay 5 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, by the processing of step S5. By switching 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 an on state, power is supplied from the lithium ion battery 21 to each load included in the second load circuit 2. In other words, in the automatic driving mode, each load included in the second load circuit 2 can continue to operate by power from the lithium ion battery 21 even if the power supply from the first load circuit 1 side is cut off. In addition, since a continuity maintenance command has been input to the additional relay 5 by the processing of step S5, the controller 6 does not need to output a close control signal to the additional relay 5.

In addition, in the case where the main relay 4 is a semiconductor relay having a self-shutoff/connection function as in this embodiment, the switching of the main relay 4 from on to off may be a switching by the self-shutoff/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, the main relay 4 may be switched from on to off by the self-shutoff/connection function. Since the main relay 4 switches from on to off by the self-shutoff/connection function faster 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 shortened, and each load included in the second load circuit 2 can be better protected.

In step S9, the controller 6 outputs a warning display signal to the display device 71 to inform the driver that an abnormality has occurred in the autonomous driving mode. The controller 6 may also output a warning sound signal to the buzzer 72. The controller 6 may also output a warning display signal to the display device 71 and a warning sound signal to the buzzer 72. The processing in this step prompts the driver to transition from the autonomous driving mode to the normal driving mode. In other words, this step is a step for requesting the driver to regain control of the driving that was being performed by the driving assistance device. Since the additional relay 5 is maintained in the on state by the processing in step S5, each load included in the second load circuit 2 is operated by power from the lithium ion battery 21, and the autonomous driving of the vehicle in the autonomous driving mode continues.

Because the condition for canceling the autonomous driving mode is the intervention of an operation by the driver, when the driver performs a driving operation such as braking, accelerating, or steering, in step S10, the controller 6 determines that the vehicle's driving mode has transitioned from the autonomous driving mode to the normal driving mode. For example, when the controller 6 receives a signal of braking operation by the driver from the brake switch 66, or a signal of steering operation by the driver from the torque sensor 67, it determines that the autonomous driving mode has been cancelled and the vehicle's driving mode has transitioned to the normal driving mode.

In step S11, the controller 6 outputs a close control signal to the main relay 4 and the additional relay 5. Because a continuity maintenance command has been input to the additional relay 5 by the process of step S5, the controller 6 does not need to output a close control signal to the additional relay 5. The controller 6 may also output a release command to the additional relay 5 in response to the continuity maintenance command output in step S5. When the process of step S11 ends, the controller 6 ends the process shown in Figures 2A and 2B.

If the operation mode of the vehicle is determined to be the normal operation mode in step S4, the process proceeds to step S12 shown in FIG. 2B. In step S12, the controller 6 outputs a continuity maintenance command to the main relay 4 and outputs a release command to the additional relay 5. As described in the main relay 4, the continuity maintenance command is a command that has a compulsory force to maintain the on state. For this reason, for example, even if an opening/closing control signal is input to the main relay 4 for some reason, if a continuity 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 continuity maintenance command. If the operation mode of the vehicle is determined to be the normal operation mode, in this step, the controller 6 maintains the main relay 4 in the on state. In addition, the controller 6 outputs a continuity maintenance command to the main relay 4 at predetermined intervals (for example, every 100 ms) until it outputs a release command to the main relay 4. This can further reduce the possibility that the main relay 4 will be turned off in the normal operation mode. In the case where the main relay 4 is a semiconductor relay having a self-shutoff/connection function as in this embodiment, this step disables the self-shutoff/connection function of the main relay 4, thereby preventing the main relay 4 from switching from on to off due to the self-shutoff/connection function. Meanwhile, the controller 6 outputs a release command to the additional relay 5, making the additional relay 5 controllable by the opening/closing control signal.

In step S13, the controller 6 determines whether or not 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 corresponds to step S6, the explanation of step S13 is based on the explanation of step S6. If the controller 6 makes a negative determination, i.e., if 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, if the controller 6 makes a positive determination, i.e., if it is determined that a voltage abnormality has occurred in the power supply system 100, the process proceeds to step S14.

If a negative determination is made in step S13, the process returns to step S4, and the vehicle operation mode is determined again. If no voltage abnormality occurs in the power supply system 100 when the vehicle is in a normal operation mode and capable of running, the processes of steps S4, S12, and S13 are repeatedly executed, so that the main relay 4 and the additional relay 5 both remain in the on state. If the ignition switch 68 is turned off while the processes of steps S4, S12, and S13 are repeatedly executed, the controller 6 determines that the vehicle has transitioned from a state capable of running 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, as in the process of step S1. The main relay 4 remains in the on state, and the additional relay 5 switches from on to off.

Here, a state of the power supply system 100 that may occur when the additional relay 5 is switched from on to off from a state in which the first load circuit 1 and the second load circuit 2 are conductive and current flows from the first load circuit 1 side to the second load circuit side will be described. For example, when the processes of steps S4, S12, and S13 are repeatedly executed, the main relay 4 and the additional relay 5 both maintain the on state, so that the 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 this embodiment, when the additional relay 5 is switched from on to off, a counter 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 counter electromotive force becomes a surge voltage that is generated instantaneously 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-interrupting/connecting function as in this embodiment, the main relay 4 may switch from on to off due to the self-interrupting/connecting function when it detects a surge voltage. However, because the self-shutoff/connection function of the main relay 4 is disabled by the process in step S12 and the main relay 4 remains on, even if a surge voltage is input to the main relay 4 by switching the additional relay 5 from on to off, the main relay 4 can be prevented from switching from on to off. This allows power to continue to be supplied from the first load circuit 1 to each load included in the second load circuit 2, and the circuit voltage of the second load circuit 2 can be maintained.

Returning to FIG. 2B, if the determination in step S13 is affirmative, the process proceeds to step S14. In step S14, the controller 6 outputs a close control signal to the main relay 4 and outputs an open control signal to the additional relay 5. In the normal operation mode, when the circuit voltage of the second load circuit 2 falls outside the predetermined voltage range, the additional relay 5 switches from on to off. On the other hand, in the normal operation mode, the main relay 4 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 falls outside the predetermined voltage range, as a result of the processing in step S12. As described above, since the additional relay 5 switches from on to off while the main relay 4 is on, there is a risk of a surge voltage occurring due to the switching of the additional relay 5 in this step as well, but the main relay 4 maintains the on state as a result of the processing in step S12. Note that, since a continuity maintenance command has been input to the main relay 4 by the processing in step S12, the controller 6 does not need to output a close control signal to the main relay 4.

In step S15, the controller 6 determines whether 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 step S6 and step S13, the explanation of step S15 is based on the explanation of step S6 and step S13. If the controller 6 makes a negative determination, i.e., 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 the controller 6 makes a positive determination, i.e., if it is determined that the voltage abnormality continues to occur in the power supply system 100, the process waits in step S15 until a positive determination is made.

If the ignition switch 68 is turned off while waiting in step S15, the controller 6 determines that the vehicle has transitioned 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, similar to the processing in step S1. The controller 6 may also output a release command to the main relay 4 in response to the continuity maintenance command output in step S12.

If a negative determination is made in step S15, the process proceeds to step S11 shown in FIG. 2A, where the controller 6 outputs a close control signal to the main relay 4 and the additional relay 5. Since a continuity maintenance command has been input to the main relay 4 by the process of step S12, the controller 6 does not need to output a close control signal to the main relay 4. The controller 6 may also output a release command to the main relay 4 in response to the continuity maintenance command output in step S12. When the process of step S11 ends, the controller 6 ends the process shown in FIG. 2A and FIG. 2B.

When the process proceeds from step S15 to step S11 and the ignition switch 68 is then turned off, the controller 6 determines that the vehicle has transitioned 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, similar to the process of step S1. The controller 6 may also output a release command to the main relay 4 in response to the continuity maintenance command output in step S12.

As described above, the power supply system 100 according to this embodiment is a power supply system mounted on a vehicle having a normal driving mode and an automatic driving mode controlled 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 with power from a lead battery 11 or an alternator 14, and is connected to a load actuator 12 and a starter motor 13 required for continuing the normal driving mode. The second load circuit 2 operates with power from a lead battery 11 or a lithium ion battery 21, and is connected to an EPS actuator 22, an ABS actuator 23, and an ADAS actuator 24 required for continuing the automatic driving mode. The main relay 4 is provided on a power supply line 3 that electrically connects the first load circuit 1 and the second load circuit 2, and provides conduction or interruption between the first load circuit 1 and the second load circuit 2. The additional relay 5 provides conduction or interruption between the lithium ion battery 21 and each load included in the second load circuit 2. In this embodiment, when the driving mode of the vehicle is the automatic driving mode (determined as the automatic driving mode in step S4 of FIG. 2A) and the circuit voltage of the second load circuit 2 falls outside a predetermined voltage range (YES in step S6 of FIG. 2A), the main relay 4 is switched from ON to OFF. When the driving mode of the vehicle is determined to be the normal driving mode (determined as the normal driving mode in step S4 of FIG. 2A), the controller 6 maintains the ON state of the main relay 4 regardless of the circuit voltage of the second load circuit 2 (steps S3 and S14 of FIG. 2B).

Since the additional relay 5 can cut off between the lithium ion battery 21 and each load included in the second load circuit 2, it is possible to prevent the lithium ion battery 21 from discharging due to the dark current of the load and the remaining battery level of the lithium ion battery 21 from decreasing when the vehicle is parked. As a result, even if the main relay 4 is turned off when the vehicle is in an 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. In addition, it is possible to prevent the lithium ion battery 21 from continuing to discharge when the voltage becomes lower than the discharge end voltage, that is, the overdischarge of the lithium ion battery 21. As a result, it is possible to mitigate the deterioration of the lithium ion battery 21 and extend the battery life of the lithium ion battery 21. In addition, by providing the additional relay 5, there is a concern that a surge voltage will be generated when the additional relay 5 is switched from on to off in the normal driving mode, and the main relay 4 will be switched from on to off due to the surge voltage. However, in the power supply system 100 and the control method for the power supply system 100 of this embodiment, the main relay 4 is maintained in the on state in the normal operation mode, so that the main relay 4 can be prevented from switching from on to off due to the surge voltage. As a result, power can be continuously supplied from the first load circuit 1 side to each load included in the second load circuit 2, and the circuit voltage of the second load circuit 2 can be maintained. In other words, according to the power supply system 100 and the control method for the power supply system 100 of this embodiment, it is possible to prevent the remaining battery charge of the lithium ion battery 21 from decreasing due to dark current discharge, and to maintain the circuit voltage of the second load circuit 2 with the voltage from the first load circuit 1 side.

In addition, in this embodiment, when the controller 6 determines that the vehicle's driving mode is the normal driving mode (determined to be the normal driving mode in step S4 in FIG. 2A), it outputs a continuity maintenance command to the main relay 4 to maintain the on state (step S12 in FIG. 2B). This allows the main relay 4 to be maintained in the on state in the normal driving mode, so that the continuity between the first load circuit 1 and the second load circuit 2 is maintained. As a result, in the normal driving mode, it is possible to prevent the main relay 4 from switching from on to off due to an external factor such as a surge voltage.

In addition, in this embodiment, the continuity maintenance command output to the main relay 4 is a command to maintain the on state of the main relay 4 regardless of the circuit voltage of the second load circuit 2 and the switching of the additional relay 5 from on to off (step S12 in FIG. 2B). As a result, even if a signal equivalent to an open control signal is input to the main relay 4 due to the circuit voltage of the second load circuit 2 or the switching of the additional relay 5 from on to off, the on state of the main relay 4 can be maintained.

In addition, in this embodiment, when the controller 6 determines that the vehicle's driving mode is the autonomous driving mode (determined to be the autonomous driving mode in step S4 of FIG. 2A), it outputs a release command to the main relay 4 to release the continuity maintenance command (step S5 of FIG. 2A). This allows the main relay 4 to be turned on and off by the opening and closing control signal in the autonomous driving mode. As a result, as in this embodiment, when the controller 6 determines that the circuit voltage of the second load circuit 2 is outside a predetermined voltage range in the autonomous driving mode, it can turn off the main relay 4 (step S8 of FIG. 2A).

In addition, in this embodiment, the main relay 4 has a self-shutoff/connection function that switches from on to off when the circuit voltage of the second load circuit 2 becomes an abnormal voltage, and the maintain continuity command is a command to disable the self-shutoff/connection function of the main relay 4, and the release command is a command to enable the self-shutoff/connection function of the main relay 4. The main relay 4 can be switched from on to off faster than when the open control signal of the controller 6 switches the main relay 4 from on to off, and the circuits included in the second load circuit 2 can be better protected when an abnormal voltage occurs.

In addition, in this embodiment, when the controller 6 determines that the vehicle is in the normal driving mode (determined to be in the automatic driving mode in step S4 of FIG. 2A), if the circuit voltage of the second load circuit 2 falls outside a predetermined voltage range, it turns off the additional relay 5 (step S14 of FIG. 2B). Since the main relay 4 maintains the on state, the circuit voltage of the second load circuit 2 can be stabilized even if a surge voltage occurs when the additional relay 5 switches from on to off. As a result, each load included in the second load circuit 2 can be protected.

In addition, in this embodiment, the controller 6 determines whether the vehicle is in a parked state, and if it determines that the vehicle is in a parked state, turns off the additional relay 5. This provides the same effect as described above. When the vehicle is parked, the lithium ion battery 21 is disconnected from each load included in the second load circuit 2, so that the lithium ion battery 21 can be prevented from being discharged due to the dark current of the load. Since the decrease in the remaining battery charge of the lithium ion battery 21 due to dark current discharge can be prevented, each load included in the second load circuit 2 can operate according to specifications using power from the lithium ion battery 21.

In addition, in this embodiment, the controller 6 acquires information regarding the state of the main relay 4 and the state of the additional relay 5, and when the additional relay 5 is in the off state, it does not output an open control signal to the main relay 4, and when the main relay 4 is in the off state, it does not output an open control signal to the additional relay 5. As a result, 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. In addition, since it is possible to prevent the power supply to the second load circuit 2 from being interrupted by simply monitoring the state of the main relay 4 and the state of the additional relay 5 without requiring complex processing, it is possible to reduce the calculation load of the controller 6 and improve the processing speed.

The above-described embodiments are described to facilitate 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 modifications and equivalents that fall within the technical scope of the present invention.

In the above embodiment, when the controller 6 determines that the driving mode of the vehicle is the normal driving mode, the controller 6 turns off the additional relay 5 when the circuit voltage of the second load circuit 2 falls outside the predetermined voltage range, and when the controller 6 determines that the vehicle is in a parked state, the controller 6 turns off the additional relay 5. However, when a current of a predetermined current value or more flows to the lithium ion battery 21 through the additional relay 5, the controller 6 does not have to turn off the additional relay 5. The predetermined current value is a current that is predetermined based on a surge voltage generated by switching the additional relay 5 from on to off. For example, in step S14 of FIG. 2B, the controller 6 acquires information on the current flowing through the additional relay 5 from a current sensor (not shown) connected in series to the additional relay 5. Then, when the current flowing to the lithium ion battery 21 through the additional relay 5 is a predetermined current value or more, the controller 6 does not output an open control signal to the additional relay 5 even if the circuit voltage of the second load circuit 2 is outside the predetermined voltage range. For example, even if the controller 6 determines that the vehicle is in a parked state, if the current flowing to the lithium ion battery 21 via the additional relay 5 is equal to or greater than a predetermined current value, the controller 6 does not output an open control signal to the additional relay 5 even if the vehicle is in a parked state. The greater the current value of the current flowing through the additional relay 5, the more likely a surge voltage is to occur when switching from on to off, so the occurrence of the surge voltage can be suppressed.

In the above embodiment, the lead battery 11 is used as the main battery, but a secondary battery such as a lithium ion battery or a nickel hydrogen battery may be used as the main battery. In the above embodiment, the lithium ion battery 21 is used as the additional battery, but multiple batteries may be used as the additional battery, or a combination of a capacitor and a DCDC converter may be used, or a nickel hydrogen battery may be used. In the above embodiment, the alternator 14 is used as the generator of the first load circuit 1, but a generator, a motor generator, or the like may be used as the generator of the first load circuit. In the above embodiment, 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, but the loads required to continue the automatic driving mode may be changed depending on the specifications of the vehicle and the specifications of the driving assistance device. In the above embodiment, the additional relay 5 and the lithium ion battery 21 are not included in the second load circuit 2, but the second load circuit 2 may include the additional relay 5 and the lithium ion battery 21. In the above embodiment, a semiconductor relay having a self-shutoff/connection function is used as the main relay 4, but a semiconductor relay or a mechanical relay not having a self-shutoff/connection function may be used as the main relay 4. In the above embodiment, a mechanical relay is used as the additional relay 5, but a semiconductor relay may be used as the additional relay 5.

In the above-described embodiment, the power supply system and the power supply system control method according to the present invention are described as being applied to a vehicle having a hands-off mode with driving assistance level 2. However, the power supply system and the power supply system control method according to the present invention can also be applied to a vehicle with driving assistance level 3.

In the above-mentioned embodiment, the power supply system and the control method of the power supply system according to the present invention are applied to a vehicle whose driving source is an engine (engine automobile). 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 whose driving source is a battery (electric automobile), a vehicle whose driving source is an engine and a battery (hybrid automobile), and a vehicle whose driving source is a fuel cell (fuel cell automobile). In short, the power supply system can be applied to a vehicle equipped with a first load circuit that operates with power from the main battery and is connected to a first load necessary for continuing the normal driving mode, a second load circuit that operates with power from the additional battery and is connected to a second load necessary for continuing the automatic driving mode, a first relay that is provided on a power supply line electrically connecting the first load and the second load and that connects or disconnects between the first load circuit and the second load circuit, a second relay that connects or disconnects between the additional battery and the second load, and a controller that determines the driving mode of the vehicle.

In the above embodiment, the control procedure is described as an example in which the vehicle's driving mode transitions from the autonomous driving mode to the normal driving mode in step S10 in FIG. 2A and then proceeds to step S11. However, after processing in step S10, the process may proceed to step S12 shown in FIG. 2B, as in the case where the vehicle's driving mode is determined to be the normal driving mode in step S4.

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 the predetermined voltage range in step S6 in FIG. 2A, and in steps S13 and S15 in FIG. 2B is determined. However, since the first load circuit 1 and the second load circuit 2 are conductive through the main relay 4 in each step, the controller 6 may determine whether or not the circuit voltage of the first load circuit 1 is outside the predetermined voltage range in each step. In the above-described embodiment, the case where the additional relay 5 is switched from on to off by the controller 6 in step S13 in FIG. 2B when the circuit voltage of the second load circuit 2 is outside the predetermined voltage range is described. However, when the driving mode of the vehicle is the normal driving mode, the condition for switching the additional relay 5 from on to off may be when the current flowing through the additional relay 5 is equal to or greater than a predetermined current threshold. For example, when the driving mode of the vehicle is determined to be the normal driving mode (determined to be the normal driving mode in step S4 in 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 in units of current and is determined based on the contact life of the additional relay 5. 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. As a result, when an excessive current flows through the additional relay 5 in the normal operation mode, the additional relay 5 can be switched from on to off to slow the rate at which the contacts of the additional relay 5 wear out.

In the above embodiment, the condition that the circuit voltage of the second load circuit 2 is outside the predetermined voltage range has been described as an example of the condition that the controller 6 turns off the main relay 4 in step S6 of FIG. 2A. 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 of the predetermined voltage range, or when the circuit voltage of the second load circuit 2 is higher than the upper limit of the predetermined voltage range. Similarly, in the above embodiment, the condition that the circuit voltage of the second load circuit 2 is outside the predetermined voltage range has been described as an example of the condition that the controller 6 turns off the additional relay 5 in step S13 of FIG. 2B. 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 of the predetermined voltage range, or when the circuit voltage of the second load circuit 2 is higher than the upper limit of the predetermined voltage range.

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...Automatic 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 (10)

A power supply system mounted on a vehicle having a normal driving mode by a driver and an automatic driving mode,
a first load circuit that is operated by power from a main battery and to which a first load necessary for continuing the normal operation mode is connected;
a second load circuit that operates using 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 electrically connecting the first load and the second load, the first relay establishing or interrupting conduction between the first load circuit and the second load circuit;
a second relay for establishing or interrupting conduction between the additional battery and the second load;
a controller for determining a driving mode of the vehicle;
When the operation mode is the automatic operation mode, the first relay is switched from on to off when a circuit voltage of the second load circuit falls outside a predetermined voltage range,
When the controller determines that the operation mode is the normal operation mode, the controller maintains the first relay in an on state regardless of the circuit voltage of the second load circuit. The power supply system according to claim 1, wherein the controller outputs a first command to the first relay to maintain the on state when the operation mode is determined to be the normal operation mode. The power supply system according to claim 2, wherein the first command is a command to maintain the on state of the first relay, regardless of the circuit voltage of the second load circuit and the switching of the second relay from on to off. The power supply system according to claim 2 or 3, wherein the controller outputs a second command to the first relay to cancel the first command when the operation mode is determined to be the automatic operation mode. the first relay has a self-shutoff/connection function of switching from on to off when a circuit voltage of the second load circuit becomes an abnormal voltage;
the first command is a command to disable the self-shutoff/connection function of the first relay,
The power supply system according to claim 4 , wherein the second command is a command to activate the self-shutoff/connection function of the first relay. The power supply system according to any one of claims 1 to 5, wherein the controller, when determining that the operation mode is the normal operation mode, turns off the second relay when the circuit voltage of the second load circuit falls outside the predetermined voltage range. The controller:
determining whether the vehicle is in a parked state;
7. The power supply system according to claim 1, wherein when it is determined that the vehicle is in a parked state, the second relay is turned off. The power supply system according to claim 6 or 7, wherein the controller does not turn off the second relay when a current equal to or greater than a predetermined current value flows to the additional battery through the second relay. The controller:
Obtaining information regarding a state of the first relay and a state of the second relay;
When the second relay is in an off state, a command to turn off the first relay is not outputted to the first relay;
9. The power supply system according to claim 1, wherein when the first relay is in an off state, a command to turn off the second relay is not output to the second relay. 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, the control method being executed by a controller, the control method comprising:
The power supply system includes:
a first load circuit that is operated by power from a main battery and to which a first load necessary for continuing the normal operation mode is connected;
a second load circuit that operates using 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 electrically connecting the first load and the second load, the first relay establishing or interrupting conduction between the first load circuit and the second load circuit;
a second relay for establishing or interrupting conduction between the additional battery and the second load;
a controller for determining a driving mode of the vehicle;
The controller:
When the operation mode is determined to be the automatic operation mode, if a circuit voltage of the second load circuit falls outside a predetermined voltage range, the first relay is switched from on to off;
A control method for a power supply system, comprising: when the operation mode is determined to be the normal operation mode, maintaining the first relay in an on state regardless of the circuit voltage of the second load circuit.