JP7815073B2 - Vehicle Power System - Google Patents

Description

The present invention relates to a vehicle power supply system.

In recent years, there has been an increase in efforts to provide access to sustainable transportation systems that take into consideration vulnerable traffic users. To achieve this, we are focusing on research and development to further improve road safety and convenience through research and development in preventive safety. We are also focusing on research and development in autonomous driving as one technology that contributes to preventive safety.

Vehicles equipped with functional units that function to ensure traffic safety, such as autonomous driving, require a stable power supply to these functional units. For example, Patent Document 1 discloses a system that can supply power to a load functioning for autonomous driving from a first power source and a third power source, which are the vehicle's power sources, and can also supply power from a second power source that is capable of charging and discharging.

Japanese Patent Application Laid-Open No. 2021-142810

The system disclosed in Patent Document 1 makes it possible to reliably operate the load that functions to ensure safety by providing redundant power supply to the load. In such a system, if power supply from the second power source to the load cannot be provided, it is conceivable that the load will not operate in order to ensure high safety. This may result in fewer opportunities to use the functional unit that ensures safety, which has been an issue.
In order to solve the above problems, the present application aims to suppress the decrease in opportunities to use functional parts due to power supply in vehicles equipped with functional parts that function to ensure traffic safety, such as autonomous driving, and ultimately contribute to the development of sustainable transportation systems.

One aspect for achieving the above object is a vehicle power supply system that is mounted on a vehicle capable of at least partial autonomous driving in an autonomous driving mode that allows the driver to be exempt from steering operations, and that includes a main power supply system having a main low-voltage power supply and a normal load, a backup power supply system having a backup low-voltage power supply and an important emergency load and connected to the main power supply system, and a high-voltage power supply unit capable of outputting a voltage higher than the rated voltage of the backup power supply system, wherein the backup power supply system has a backup power supply control device that monitors the status of the backup low-voltage power supply and controls the input and output of power from the backup low-voltage power supply, and the backup power supply control device is capable of executing an estimation process to estimate a suppliable power amount indicating the amount of power or power that can be supplied from the backup low-voltage power supply to the important emergency load, and when the vehicle is not autonomously driving in the autonomous driving mode, the backup power supply control device executes the estimation process, and when the suppliable power amount estimated in the estimation process is equal to or greater than a first threshold value, If the second threshold is exceeded, the backup power supply control device outputs a signal indicating that the vehicle is permitted to drive autonomously in the autonomous driving mode; when the vehicle is driving autonomously in the autonomous driving mode, the backup power supply control device executes the estimation process, and if the available power supply estimated in the estimation process is less than a second threshold, outputs a signal indicating that the vehicle is prohibited from driving autonomously in the autonomous driving mode; when the vehicle is driving autonomously in the autonomous driving mode, the backup power supply control device executes the estimation process, and if the available power supply estimated in the estimation process is less than or equal to a third threshold, outputs a signal indicating that the vehicle is permitted to continue in the autonomous driving mode and is permitted to charge the backup low-voltage power supply with power generated by the high-voltage power supply unit; the first threshold is a threshold related to the amount of power or power determined based on the amount of power required to operate the emergency important load when the vehicle is driving autonomously in the autonomous driving mode.

With the above configuration, a vehicle capable of at least partial autonomous driving can continue autonomous driving even if the available power supply from the backup low-voltage power supply decreases. This prevents a decrease in opportunities to use autonomous driving due to the supply of power to loads related to autonomous driving. This increases the opportunities and time during which the vehicle can perform autonomous driving, thereby improving marketability.

1 is a schematic diagram of a vehicle power supply system according to an embodiment; FIG. 10 is a diagram showing an example of the configuration of an important load in an emergency. 3 is a flowchart showing the operation of the vehicle power supply system. 3 is a flowchart showing the operation of the vehicle power supply system. 3 is a timing chart showing the operation of the vehicle power supply system.

One embodiment of a vehicle power supply system of the present invention will be described below with reference to the accompanying drawings.

[1. Configuration of vehicle power supply system]
[1-1. Overall configuration of vehicle power supply system]
Fig. 1 is a schematic diagram of a vehicle power supply system 1. In Fig. 1, solid lines indicate power lines and dashed lines indicate signal lines.

In this embodiment, the vehicle power supply system 1 of the vehicle V includes a main power supply system 10, a backup power supply system 20 connected to the main power supply system 10, a high-voltage power supply system 30, and a step-down device 40. The high-voltage power supply system 30 is connected to the main power supply system 10 and the backup power supply system 20 via the step-down device 40. The step-down device 40 steps down the power flowing through the high-voltage power supply system 30 and outputs it to the main power supply system 10 and/or the backup power supply system 20. The step-down device 40 is, for example, a DC/DC converter.

In this embodiment, as an example, the vehicle V is an electric vehicle equipped with a rotating electric machine MG as a power source for traveling. The rotating electric machine MG is, for example, a three-phase motor, and generates driving force using power supplied by an inverter unit (not shown), causing the vehicle V to travel. The vehicle V is equipped with a drive unit 321 equipped with the rotating electric machine MG, which will be described later. The vehicle V is equipped with a high-voltage power supply 31 that supplies driving power to the drive unit 321. The drive unit 321 is a load that receives a supply of high-voltage power output by the high-voltage power supply 31, and is included in the high-voltage load 32, which will be described later.

The vehicle V may be a vehicle equipped with an internal combustion engine. The internal combustion engine may function as a power source for driving the vehicle V. Alternatively, the internal combustion engine may function as a power source for driving a generator (not shown) and charge the high-voltage power supply 31 described below. In other words, the vehicle V may be an electric vehicle without an internal combustion engine, a hybrid vehicle equipped with an internal combustion engine and a rotating electric machine MG for driving the vehicle, or a vehicle driven by an internal combustion engine. The vehicle V is, for example, a vehicle capable of autonomous driving or automatic driving. When the vehicle V is equipped with an internal combustion engine, the high-voltage load 32 supplied with power from the high-voltage power supply 31 includes, for example, a starter motor.

[1-2. Configuration of main power supply system]
The main power supply system 10 includes a main low-voltage power supply 11 and a normal load 12 .

The main low-voltage power supply 11 is a power supply with a lower voltage than the high-voltage power supply 31. The main low-voltage power supply 11 outputs, for example, a direct current of 12 V. The main low-voltage power supply 11 is, for example, a secondary battery that can be charged and discharged. Specifically, the main low-voltage power supply 11 may be a lead battery, a lithium-ion battery, a lithium polymer battery, a lithium iron phosphate battery, a metal hydride battery, or other batteries.

The main low-voltage power supply 11 is provided on the connection line L11. One end of the connection line L11 is connected to a contact C11 formed on the connection line L10, and the other end is connected to a ground line having a reference potential of the vehicle power supply system 1. The positive side of the main low-voltage power supply 11 is connected to the contact C11 side of the connection line L11, and the negative side is connected to the ground line side of the connection line L11.

A normal load 12 is connected to one end of the connection line L10. The normal load 12 (EL in the figure) is an electric power load mounted on the vehicle V. The normal load 12 may be a single device or may include multiple devices. In this embodiment, the normal load 12 is a functional unit that performs functions related to the running of the vehicle V. The normal load 12 includes, for example, loads that perform functions related to running operations, stopping operations, or driving control of the vehicle V. The normal load 12 operates at a lower voltage than the high-voltage load 32, and therefore can be called a low-voltage load in comparison with the high-voltage load 32. The normal load 12 may also include devices in the vehicle V that are known as auxiliary equipment.

Specifically, the normal load 12 includes an ECU 50 (Electronic Control Unit) capable of executing operational control of the vehicle V. The ECU 50 shown in FIG. 1 may be composed of a single ECU, or may include multiple ECUs. For example, the normal load 12 may include some of the multiple ECUs provided in the vehicle V. Furthermore, the normal load 12 may include a control unit (not shown) that is mounted on the vehicle V and is different from the ECU 50.

The normal load 12 may also include an auxiliary load used for braking the vehicle V, such as an automatic braking system. The normal load 12 may also include an auxiliary load used for steering the vehicle V, such as an automatic steering system. The normal load 12 may also include an auxiliary load used for acquiring external information about the vehicle V, such as LiDAR (Light Detection and Ranging). The normal load 12 may also include instruments such as a wiper system, a power window system, and a meter panel.

[1-3. Configuration of backup power supply system]
The backup power supply system 20 includes a backup power supply unit 21 and an important emergency load 22 .

The backup power supply unit 21 includes a backup low-voltage power supply 23, a switching device 24, and a backup power supply control device 25 that controls the switching device 24.

The backup power supply unit 21 has a first external connection terminal T211, a second external connection terminal T212, and a ground terminal T213. The other end of the connection line L10 is connected to the first external connection terminal T211. The ground terminal T213 is connected to the ground line.

The emergency important load 22 (EL in the figure) is an electric power load mounted on the vehicle V. The emergency important load 22 may be a single device or may include multiple devices. The emergency important load 22 operates at a lower voltage than the high-voltage load 32, and therefore can be called a low-voltage load in comparison with the high-voltage load 32.

The emergency important load 22 is connected to the second external connection terminal T212 of the backup power supply unit 21 via the connection line L21.

The switching device 24 has a first terminal T241, a second terminal T242, and a third terminal T243. The first terminal T241 is connected to the first external connection terminal T211 of the backup power supply unit 21 by a connection line L211. The second terminal T242 is connected to the second external connection terminal T212 of the backup power supply unit 21 by a connection line L212.

The switching device 24 includes a connection line L241 connecting the first terminal T241 and the second terminal T242. A first switch SW1 is provided on the connection line L241. In this embodiment, the first switch SW1 is a switch with a normally open (N.O.) contact. That is, when no operation signal is applied to the first switch SW1, the first switch SW1 is maintained in an OFF state, and is a contact that maintains the connection line L241 in an interrupted state. When an operation signal is applied, the first switch SW1 switches to an ON state, connecting the first terminal T241 and the second terminal T242.

For example, if the first switch SW1 is configured as an electromagnetic switch that opens and closes using electromagnetic force, the first switch SW1 is maintained in an off state when no electromagnetic force is generated by the operating current, and maintains the connection line L241 in an interrupted state.
The first switch SW1 may be an electromagnetic switch such as an electromagnetic contactor, an electromagnetic switch, or a relay, or may be a semiconductor switch element, or may be a circuit such as a DC/DC converter having a switching function.

The switching device 24 includes a connection line L242 that connects the connection line L241 and the third terminal T243. One end of the connection line L242 is connected to the connection line L241 at a contact C241 formed between the first switch SW1 of the connection line L241 and the second terminal T242, and the other end is connected to the third terminal T243.

A second switch SW2 is provided on the connection line L242. When the second switch SW2 is in the on state, it connects the connection line L242, and when it is in the off state, it disconnects the connection line L242.

The second switch SW2 may be an electromagnetic switch such as an electromagnetic contactor, electromagnetic switch, or relay, or may be a semiconductor switch element, or may be a circuit with a switching function such as a DC/DC converter. In this embodiment, the second switch SW2 is a DC/DC converter. Therefore, as described below, when the second switch SW2 is in the on state, it can step up or step down the voltage output from the connection line L242 to the contact C241. In other words, the second switch SW2 in this embodiment has the function of connecting and disconnecting the connection line L242 and the function of converting the voltage output from the connection line L242 to the contact C241.

The switching device 24 includes a connection line L243 connected in parallel to the connection line L241. One end of the connection line L243 is connected to a contact C242 formed between the first terminal T241 of the connection line L241 and the first switch SW1. The other end of the connection line L243 is connected to a contact C243 formed between the contact C241 of the connection line L241 and the second terminal T242. A third switch SW3 is provided on the connection line L243.

In this embodiment, the third switch SW3 is a switch with a normally closed (N.C.) contact. That is, the third switch SW3 is a contact that is maintained in the ON state when no operation signal is applied to the third switch SW3. When an operation signal is applied to the third switch SW3, the third switch SW3 switches to the OFF state, bringing the connection line L243 into a connected state.

For example, if the third switch SW3 is configured as an electromagnetic switch that opens and closes using electromagnetic force, the third switch SW3 is maintained in an on state when no electromagnetic force is generated by the operating current, and maintains the connection line L243 in a connected state.
The third switch SW3 may be an electromagnetic switch such as an electromagnetic contactor, an electromagnetic switch, or a relay, or may be a semiconductor switch element, or may be a circuit such as a DC/DC converter having a switching function.

In this embodiment, the first switch SW1 and the third switch SW3 are modularized as a switch module 241. The specific configuration of the switch module 241 is not limited; for example, the switch module 241 may be a single semiconductor device or a circuit including multiple devices.

The switching device 24 includes a connection line L244 that connects the connection line L241 to the ground line. One end of the connection line L244 is connected to a contact C244 formed between the first switch SW1 of the connection line L241 and the contact C241. The other end of the connection line L244 is connected to the ground line. A capacitor CP is provided on the connection line L244.

The backup low-voltage power supply 23 is a power supply with a lower voltage than the high-voltage power supply 31. The backup low-voltage power supply 23 outputs a direct current of, for example, 12 V. The backup low-voltage power supply 23 is, for example, a secondary battery that can be charged and discharged. Specifically, the backup low-voltage power supply 23 may be a lead battery, a lithium-ion battery, a lithium polymer battery, a lithium iron phosphate battery, a metal hydride battery, or other batteries.

The backup low-voltage power supply 23 is connected to the connection line L213. One end of the connection line L213 is connected to the third terminal T243 of the switching device 24. The other end of the connection line L213 is connected to the ground line. The backup low-voltage power supply 23 is connected to the connection line L213 so that its positive side is on the third terminal T243 side of the switching device 24 and its negative side is on the ground line side.

When the second switch SW2 is in the on state, the backup low-voltage power supply 23 supplies power to the backup power supply system 20 from the connection line L213 through the connection line L242 of the switching device 24. The power output from the backup low-voltage power supply 23 is stepped up or down to the desired voltage by the second switch SW2 and supplied to the backup power supply system 20. When the second switch SW2 is in the off state, the connection line L242 of the switching device 24 is cut off, so no power is supplied from the backup low-voltage power supply 23 to the backup power supply system 20.

As described above, in the backup power supply system 20, a first switch SW1 having a normally open contact and a third switch SW3 having a normally closed contact are connected in parallel between the first terminal T241 and the second terminal T242.

When at least one of the first switch SW1 and the third switch SW3 is in the on state, the backup power supply system 20 is connected to the main power supply system 10. In this state, power can be supplied from the backup low-voltage power supply 23 to the main power supply system 10 via the first external connection terminal T211, and power can also be supplied from the main low-voltage power supply 11 to the emergency important load 22.

On the other hand, when both the first switch SW1 and the third switch SW3 are in the off state, the connection between the backup power supply system 20 and the main power supply system 10 is cut off.

The backup power supply control device 25 (BMS in the figure) is connected to the first switch SW1, the second switch SW2, and the third switch SW3 via signal lines. The backup power supply control device 25 controls the switching of the first switch SW1, the second switch SW2, and the third switch SW3 under the control of the ECU 50. The backup power supply control device 25 includes a processor such as a CPU (Central Processing Unit), and controls the backup power system 20 through collaboration between software and hardware by executing a program using the processor. In this case, the backup power supply control device 25 may include a memory unit that stores programs and data, such as a ROM (Read Only Memory). The backup power supply control device 25 may also be configured as programmed hardware.

The backup power supply control device 25 outputs operation signals to each of the first switch SW1, second switch SW2, and third switch SW3 via signal lines. The backup power supply control device 25 can switch each of the first switch SW1, second switch SW2, and third switch SW3 between a state in which an operation signal is output and a state in which an operation signal is not output.

The first switch SW1 is a normally open switch. The backup power supply control device 25 outputs an operation signal to the first switch SW1 to switch the first switch SW1 from an off state to an on state. The third switch SW3 is a normally closed switch. The backup power supply control device 25 outputs an operation signal to the third switch SW3 to switch the third switch SW3 from an on state to an off state.

The backup power supply control device 25 outputs an operation signal to the second switch SW2, thereby switching the second switch SW2 between an on state and an off state. The backup power supply control device 25 also outputs an operation signal to the second switch SW2, thereby controlling the voltage increase or decrease of the second switch SW2. In other words, the backup power supply control device 25 controls the output voltage of the second switch SW2.

The backup power supply control device 25 operates by receiving power from, for example, the high-voltage power supply unit 36 or the backup low-voltage power supply 23.

The backup power supply control device 25 has the function of detecting the state of charge of the backup low-voltage power supply 23. The state of charge of the backup low-voltage power supply 23 is, for example, the SOC (State of Charge). The backup power supply control device 25 detects the remaining battery capacity of the backup low-voltage power supply 23, for example, by detecting the voltage across the backup low-voltage power supply 23. The backup power supply control device 25 may also detect the remaining battery capacity of the backup low-voltage power supply 23 by counting the current input and output to and from the backup low-voltage power supply 23. The backup power supply control device 25 may calculate the SOC, for example, based on the full charge capacity (FCC: Full Charge Capacity) of the backup low-voltage power supply 23 and the RM (Remaining Capacity) indicating the actual remaining capacity. Using these functions, the backup power supply control device 25 executes an estimation process to estimate the available power supply, which is the amount of power (e.g., in watt-hours [Wh]) or power (e.g., in watts [W]) that the backup low-voltage power supply 23 can output. The estimation process is a process to estimate the available power supply, which indicates the amount of power or power that the backup low-voltage power supply 23 can supply to the emergency important load 22, and can be rephrased as an available power supply estimation process.

In this embodiment, the important emergency load 22 is a functional unit that performs functions related to the driving of the vehicle V, and includes, for example, a load that performs functions related to driving operations, stopping operations, or driving control of the vehicle V. The important emergency load 22 includes a load that performs functions to respond to an emergency while the vehicle V is driving. Specifically, the important emergency load 22 includes a load that performs functions related to the execution of a minimal risk maneuver (MRM) related to the driving of the vehicle V. For example, MRM includes operations or controls that correspond to at least one of the minimum driving operations, stopping operations, and driving controls required to safely move the vehicle V to the shoulder of the road and stop it even if the driving force of the drive source is lost.

The emergency important load 22 may include part or all of the aforementioned ECU 50, which is capable of executing driving control of the vehicle V. The emergency important load 22 may be a control unit mounted on the vehicle V and may include a control unit (not shown) different from the ECU 50.

Some of the loads included in the emergency important loads 22 may overlap with the loads included in the normal loads 12 of the main power supply system 10. That is, some of the normal loads 12 may also be emergency important loads 22, and these loads will belong to both the main power supply system 10 and the backup power supply system 20. This configuration allows the emergency important loads 22 to be made redundant. In other words, the emergency important loads 22 that overlap with the normal loads 12 of the main power supply system 10 can operate using power supplied to the main power supply system 10 and can also operate using power supplied to the backup power supply system 20. Therefore, the emergency important loads 22 that overlap with the normal loads 12 of the main power supply system 10 can operate even if an abnormality occurs in the main power supply system 10, and can also operate even if an abnormality occurs in the backup power supply system 20.

[1-4. Configuration of high-voltage power supply system]
The high-voltage power supply system 30 includes a high-voltage power supply 31 and a high-voltage load 32 .

The high-voltage power supply 31 is a power supply that supplies power at a higher voltage than the main low-voltage power supply 11 and the backup low-voltage power supply 23. The high-voltage power supply 31 is connected to a connection line L31. One end of the connection line L31 is connected to a ground line, and the negative side of the high-voltage power supply 31 is connected to the ground line side of the connection line L31.

The high-voltage load 32 is an electric power load that operates at a higher voltage than the normal load 12 and the important emergency load 22, and is powered by electric power supplied from the high-voltage power supply 31. In this embodiment, the high-voltage load 32 includes a drive unit 321 that drives the vehicle V, and an air conditioning device 322 (A/C in the figure) that conditions the air inside the passenger compartment of the vehicle V.

The drive unit 321 includes a rotating electric machine MG and a power control unit PCU that controls the rotating electric machine MG. The power control unit PCU includes a DC/DC converter (not shown) and an inverter (not shown), etc.

The drive unit 321 is connected to the other end of the connection line L31. The drive unit 321 converts the DC power supplied from the high-voltage power supply 31 into three-phase AC power using the power control unit PCU and supplies it to the rotating electric machine MG. As a result, the rotating electric machine MG generates power to drive the vehicle V using the power from the high-voltage power supply 31.

The air conditioning unit 322 is connected to a connection line L32, which connects to the connection line L31 at a contact C31 formed between the high-voltage power supply 31 and the drive unit 321 of the connection line L31. The air conditioning unit 322 operates using power from the high-voltage power supply 31.

The step-down device 40 is provided on the connection line L40. One end of the connection line L40 is connected to contact C32, and the other end is connected to contact C12. Contact C32 is a contact formed between the high-voltage power supply 31 and contact C31 of the connection line L31. Contact C12 is a contact formed between contact C11 of the connection line L10 and the other end of the connection line L10. Here, the other end of the connection line L10 corresponds to the first external connection terminal T211 of the backup power supply system 20.

In this way, the high-voltage power supply system 30 is connected to the main power supply system 10 and the backup power supply system 20 via the step-down device 40.

The step-down device 40 reduces the voltage of the power flowing through the high-voltage power supply system 30. The step-down device 40 is, for example, a DC/DC converter. The step-down device 40 reduces the voltage output by the high-voltage power supply system 30 and supplies it to the main power supply system 10 and the backup power supply system 20.

The step-down device 40 can be switched between a connected state and a disconnected state. When the step-down device 40 is in a connected state, the high-voltage power supply system 30 is connected to the main power supply system 10 and the backup power supply system 20 via the connection line L40 and the step-down device 40. When the step-down device 40 is in a disconnected state, the high-voltage power supply system 30 is disconnected from the main power supply system 10 and the backup power supply system 20.

The high-voltage power supply 31 may be a power generation device mounted on the vehicle V, or a battery mounted on the vehicle V. Examples of batteries include secondary batteries that can be charged and discharged. Specifically, a lithium-ion battery, lithium polymer battery, lithium iron phosphate battery, metal hydride battery, or other battery can be used as the high-voltage power supply 31. In this case, the high-voltage power supply 31 outputs a direct current of, for example, 200 V.

When the high-voltage power supply 31 includes a secondary battery, the high-voltage power supply 31 may also include a power generation device that supplies power to the secondary battery. Alternatively, the high-voltage power supply 31 may consist solely of a power generation device. For example, a rotating electric machine MG may be used as the power generation device. For example, when braking the vehicle V, the rotating electric machine MG may function as a regenerative brake, and the regenerative power generated by the rotating electric machine MG may be used as the high-voltage power supply 31. Furthermore, when the vehicle V has an internal combustion engine, the vehicle V includes a generator driven by the power of the internal combustion engine. This generator may be used as the high-voltage power supply 31. The generator outputs the generated AC current via a boost circuit or rectifier circuit (not shown). Alternatively, the AC current output by the generator may be supplied to the step-down device 40 directly or via a boost circuit or rectifier circuit (not shown).

The high-voltage power supply 31 and the step-down device 40 constitute a high-voltage power supply unit 36. The high-voltage power supply unit 36 is capable of outputting a voltage higher than the rated voltage of the backup power supply system 20. The high-voltage power supply unit 36 may also be capable of outputting a voltage higher than the rated voltage of the main low-voltage power supply 11.
The high-voltage power supply unit 36 is configured by a high-voltage power supply 31 formed, for example, from a secondary battery, and a step-down device 40. When the high-voltage power supply 31 is configured by a generator driven by an internal combustion engine, a boost circuit or a rectifier circuit (not shown) connected to the generator may be used as a component replacing the step-down device 40. In other words, the high-voltage power supply unit 36 may be configured by the generator and its peripheral circuits.

The high-voltage power supply unit 36 is capable of operating in at least a normal operation mode and a high-voltage mode, and switches between the normal operation mode and the high-voltage mode, for example, under the control of the ECU 50. The normal operation mode is an operation mode intended to supply power to the normal load 12 and the emergency important load 22. The output voltage of the high-voltage power supply unit 36 in the normal operation mode is a voltage within the range of the rated input voltage of the normal load 12 and the emergency important load 22. For example, in a vehicle V in which the rated output voltage of the main low-voltage power supply 11 and the backup low-voltage power supply 23 is 12 V, the high-voltage power supply unit 36 outputs a voltage in the range of 12 V to 15 V in the normal operation mode.

The high-voltage mode is an operating mode intended to charge the backup low-voltage power supply 23 with power supplied by the high-voltage power supply unit 36. The output voltage of the high-voltage power supply unit 36 in high-voltage mode is capable of charging the backup low-voltage power supply 23, and is preferably a voltage that allows high-voltage charging of the backup low-voltage power supply 23.

Even in the normal operation mode, if the output voltage of the high-voltage power supply unit 36 is higher than the output voltage of the backup low-voltage power supply 23, the backup low-voltage power supply 23 is charged by the power of the high-voltage power supply unit 36. High-voltage charging refers to an operation that increases the state of charge of the backup low-voltage power supply 23 in a shorter time than when the backup low-voltage power supply 23 is charged in the normal operation mode. In other words, high-voltage charging refers to an operation in which the high-voltage power supply unit 36 operates in the high-voltage mode to quickly charge the backup low-voltage power supply 23. In the high-voltage mode, the high-voltage power supply unit 36 outputs a voltage that is, for example, two or three times or more than that in the normal operation mode.
Furthermore, when the backup low-voltage power supply 23 is charged by the power output from the high-voltage power supply unit 36, the main low-voltage power supply 11 may be charged at the same time.

The vehicle power supply system 1 includes an ECU 50. As described above, the ECU 50 may include multiple ECUs, or may be a single device. The ECU 50 corresponds to an example of a vehicle control device.

The ECU 50 is connected by signal lines to the normal load 12, the emergency important load 22, the backup power supply control device 25, and the high-voltage load 32. The devices to which the ECU 50 is connected are not limited to those listed above. The ECU 50 may also be connected to devices installed in the vehicle V that are not shown in FIG. 1.

The ECU 50 includes a processor such as a CPU, and controls each part of the vehicle power supply system 1 through collaboration between software and hardware by executing a program using the processor. In this case, the ECU 50 may also include a memory unit, such as a ROM, that stores programs and data. The memory unit may also be configured as programmed hardware.

An operation unit 55 is connected to the ECU 50. The operation unit 55 includes switches and the like operated by the user of the vehicle V. For example, the operation unit 55 includes a start/stop switch (SSSW) 56 that the user operates to instruct the vehicle V to start and stop. The operation unit 55 also includes switches and the like that the user uses to instruct the vehicle V to perform autonomous driving. The operation unit 55 may be a wireless communication device that is wirelessly connected to a remote control device (not shown) and detects operations performed by the remote control device. Here, the user of the vehicle V is, for example, the driver of the vehicle V, but may also include someone other than the driver who uses the vehicle V.

When the vehicle V is stopped, the vehicle power supply system 1 is in an off state. When the vehicle power supply system 1 is in an off state, the ECU 50 remains operable using power supplied from the high-voltage power supply 31. This state may be what is known as a sleep state or a low-power consumption state. In the sleep state or low-power consumption state, the ECU 50 may be in a state in which, for example, power supply to some of the ECU 50's components is stopped. Furthermore, in the sleep state or low-power consumption state, the operating clock rate of the ECU 50 and the sampling frequency at which the ECU 50 detects the state of the operation unit 55 or the states of various sensors may be set to a longer cycle than when the vehicle V is operating.

When the vehicle power supply system 1 is in the off state, power is supplied to the normal load 12 and the emergency important load 22. This is to operate the emergency important load 22 and the normal load 12 while the vehicle power supply system 1 is in the off state. For example, the ECU 50 may monitor the detection values of a sensor included in the emergency important load 22 or a sensor connected to the emergency important load 22. Another example is a case where a camera included in the emergency important load 22 performs a function of monitoring the surroundings of a parked vehicle V. In such cases, to operate the emergency important load 22, power is supplied from the high-voltage power supply unit 36 to the emergency important load 22. Power is also supplied from the high-voltage power supply unit 36 to the normal load 12. This power is referred to as dark current. As described above, because the third switch SW3 is normally closed, power can be supplied from the main power supply system 10 to the emergency important load 22 via the third switch SW3 even when the backup power supply control device 25 is stopped.

In the vehicle power supply system 1, when the vehicle V is in a startup state, power is supplied from the high-voltage power supply 31 to each component of the main power supply system 10. Furthermore, power is supplied from the high-voltage power supply unit 36 to the main power supply system 10 and the emergency important load 22. When the vehicle V is in a stopped state, as described above, a dark current flows from the high-voltage power supply unit 36 to the emergency important load 22.

If a short circuit or ground fault occurs in the main power supply system 10, the power supply from the high-voltage power supply unit 36 to the emergency important load 22 may be stopped to protect the vehicle power supply system 1. For example, fuses (not shown) are provided at multiple locations in the circuits that make up the vehicle power supply system 1. If a ground fault or short circuit occurs, the fuses provided in the connection lines L31, L32, L40, etc. will blow, stopping the power supply from the high-voltage power supply unit 36 to the emergency important load 22. The protection function may also shut off the output of the step-down device 40.

Even in such a case, the vehicle power supply system 1 can supply power from the backup low-voltage power supply 23 to the emergency important load 22 so that the power supply to the emergency important load 22 is not interrupted. This function realizes minimal-risk maneuvers while the vehicle V is autonomously driving. Specifically, by switching the second switch SW2 on, the backup low-voltage power supply 23 is connected to the connection line L212, and power supply from the backup low-voltage power supply 23 to the emergency important load 22 begins. Alternatively, while the emergency important load 22 is operating during startup of the vehicle V, the backup power supply control device 25 may keep the second switch SW2 in the OFF state to prepare for a situation in which the power supply from the step-down device 40 to the backup power supply system 20 is interrupted. In this case, the output voltage of the second switch SW2 may be adjusted in accordance with the output voltage of the step-down device 40 so that current does not flow from the second switch SW2 toward the step-down device 40.

In order to achieve minimal-risk maneuvers, the ECU 50 sets the condition for the vehicle V to perform autonomous driving as being that the backup low-voltage power supply 23 is able to supply power to the emergency critical load 22.

The operating state in which vehicle V is performing autonomous driving is called autonomous driving mode. In autonomous driving mode, vehicle V drives without requiring at least steering operation by the driver. That is, in autonomous driving mode, autonomous driving control unit 220 drives vehicle V without requiring steering by the user, using at least lane keeping control unit 221 and steering control unit 222. In autonomous driving mode, autonomous driving control unit 220 performs partial autonomous driving. Partial autonomous driving means executing some of the autonomous driving-related functions possessed by autonomous driving control unit 220. For example, this may or may not include steering by lane keeping control unit 221 and steering control unit 222, while executing autonomous driving functions by brake control unit 223 and driving control unit 224.

The ECU 50 executes autonomous driving of the vehicle V when triggered by operation of the operation unit 55 or a preset operating state of the vehicle V. That is, it initiates the autonomous driving mode of the vehicle V. In this case, the ECU 50 controls the autonomous driving control unit 220 to start autonomous driving. Furthermore, while the vehicle V is performing autonomous driving, the ECU 50 stops the autonomous driving of the vehicle V when triggered by operation of the operation unit 55 or a preset operating state of the vehicle V. In this case, the ECU 50 controls the autonomous driving control unit 220 to end the autonomous driving mode, stop autonomous driving, and transition to normal driving mode. The normal driving mode is an operating mode that requires steering by the user to drive the vehicle V.

The ECU 50 causes the backup power supply control device 25 to estimate the available power supply of the backup low-voltage power supply 23. In this case, the backup power supply control device 25 estimates the available power supply and outputs the estimated value or a signal based on the estimated value.

When the backup power supply control device 25 outputs a signal, it means that the backup power supply control device 25 outputs a signal indicating that autonomous driving of the vehicle V is permitted, a signal indicating that continuation of autonomous driving of the vehicle V is permitted, and a signal indicating that autonomous driving of the vehicle V is prohibited. These signals may be output by the ECU 50 or another control device based on estimated values, but this embodiment describes an example in which the backup power supply control device 25 outputs them.

When the ECU 50 starts autonomous driving of the vehicle V, the backup power supply control device 25 performs estimation processing to determine whether the power that can be supplied from the backup low-voltage power supply 23 is sufficient to achieve a minimal-risk maneuver. In making this determination, the backup power supply control device 25 references various thresholds, which will be described later. These thresholds are held or stored in advance by the ECU 50 or the backup power supply control device 25.

If the backup power supply control device 25 determines that the backup low-voltage power supply 23 does not have sufficient power to supply, it outputs a signal indicating that autonomous driving of the vehicle V is to be prohibited. This signal may be called, for example, a prohibition signal. If the prohibition signal is input from the backup power supply control device 25, the ECU 50 does not start autonomous driving. Furthermore, if the prohibition signal is input from the backup power supply control device 25 while autonomous driving of the vehicle V is being performed, the ECU 50 terminates autonomous driving.

When the backup power supply control device 25 determines that the backup low-voltage power supply 23 has sufficient power to supply, or when the power supply is insufficient but can be restored by charging, it outputs a signal indicating that autonomous driving of the vehicle V is permitted, or a signal indicating that continuation of autonomous driving of the vehicle V is permitted. These signals can be referred to as, for example, permission signals.

When autonomous driving of vehicle V is initiated, ECU 50 initiates autonomous driving of vehicle V on the condition that an authorization signal has been input from backup power supply control device 25. Furthermore, if an authorization signal is input from backup power supply control device 25 while autonomous driving of vehicle V is being performed, ECU 50 continues autonomous driving. While autonomous driving of vehicle V is being performed, ECU 50 determines whether an authorization signal has been input from backup power supply control device 25 at predetermined time intervals, and terminates autonomous driving if the state in which an authorization signal has not been input continues for a predetermined time or longer.

[1-5. Configuration of important loads in emergencies]
FIG. 2 is a block diagram showing an example of the configuration of the emergency important load 22. As shown in FIG.
2 illustrates an autonomous driving control unit 220 as an example of a functional unit included in the emergency important load 22. The autonomous driving control unit 220 includes, for example, a lane keeping control unit 221, a steering control unit 222, a brake control unit 223, and a driving control unit 224. Each functional unit constituting the autonomous driving control unit 220 may be configured with multiple ECUs, or the multiple functional units shown in FIG. 2 may be configured with a single ECU, and the autonomous driving control unit 220 may be a single ECU. Furthermore, the autonomous driving control unit 220 may be configured with a device having a control function different from an ECU, or may be realized by a computer executing software.

Figure 2 shows a sensing unit 61, an electric steering unit 62, a brake drive device 63, and a throttle control device 64 as examples of functional units included in the emergency important load 22. Some or all of these may be included in the normal load 12. In addition, the emergency important load 22 may have functional units and drive units not shown in Figure 2.

The sensing unit 61 includes one or more sensors that detect the conditions outside the vehicle V and the driving conditions of the vehicle V. The sensing unit 61 may be, for example, the above-mentioned LiDAR, a camera, a 4D sensor composed of radar and/or laser, an acceleration sensor, a gyro sensor, a geomagnetic sensor, a GNSS (Global Navigation Satellite System) unit, etc. The sensing unit 61 may be a unit that integrates multiple sensors, or the sensors included in the sensing unit 61 may be individually connected to the autonomous driving control unit 220.

While vehicle V is performing autonomous driving, sensing unit 61 outputs information necessary for vehicle V to perform autonomous driving to autonomous driving control unit 220 in accordance with the control of autonomous driving control unit 220. When vehicle V is not performing autonomous driving, sensing unit 61 outputs information, such as information for vehicle V's car navigation system to display the position of vehicle V, to autonomous driving control unit 220 and ECU 50.

The electric steering unit 62 controls the steering device of the vehicle V. For example, the electric steering unit 62 controls the steering of the vehicle V by operating a motor connected to a steering gearbox (not shown).

The electric steering unit 62 drives the steering device of the vehicle V in accordance with the control of the autonomous driving control unit 220 while the vehicle V is performing autonomous driving. This allows the vehicle V to travel without the user performing steering operations. When the vehicle V is not performing autonomous driving, the electric steering unit 62 operates the steering device of the vehicle V in response to user operation via the operation unit 55 or a steering wheel (not shown).

The brake drive device 63 controls the braking device of the vehicle V. For example, the brake drive device 63 operates the brake system of the vehicle V using a motor or hydraulic device to decelerate, stop, and maintain the stopped state of the vehicle V.

The brake drive device 63 controls the braking device in accordance with the control of the autonomous driving control unit 220 while the vehicle V is performing autonomous driving. This allows the vehicle V to perform autonomous driving, automatically slowing down and stopping the vehicle without the user operating the brakes. When the vehicle V is not performing autonomous driving, the brake drive device 63 operates the braking device of the vehicle V in response to user operation via the operation unit 55 or a brake pedal (not shown).

The throttle control device 64 controls the drive source that drives the vehicle V. In vehicles V equipped with an internal combustion engine, the throttle control device 64 controls the supply of fuel to the internal combustion engine, and in vehicles V equipped with a motor as a drive source, the throttle control device 64 controls the rotation of the motor.

The throttle control device 64 controls the drive source in accordance with the control of the autonomous driving control unit 220 while the vehicle V is performing autonomous driving. As a result, the vehicle V performs autonomous driving that automatically accelerates the vehicle V without the user performing any operation for acceleration, such as throttle operation. When the vehicle V is not performing autonomous driving, the throttle control device 64 operates the drive source of the vehicle V in response to user operation via the operation unit 55 or an accelerator pedal (not shown).

The lane keeping control unit 221 and steering control unit 222 implement the lane keeping function included in the autonomous driving function of the vehicle V. For example, the lane keeping control unit 221 calculates the steering amount and steering direction of the vehicle V based on information detected by the sensing unit 61 so that the vehicle V maintains a state in which it is traveling at an appropriate position relative to the lane. The steering control unit 222 controls the electric steering unit 62 based on the steering amount and steering direction calculated by the lane keeping control unit 221, and steers the vehicle V so that the vehicle V maintains a state in which it is traveling at an appropriate position relative to the lane.

The brake control unit 223 controls the brake drive device 63 to realize the brake control function included in the autonomous driving function of the vehicle V. For example, the brake control unit 223 causes the brake drive device 63 to maintain an appropriate driving speed of the vehicle V. Also, for example, the brake control unit 223 causes the brake drive device 63 to maintain an appropriate distance from other vehicles or obstacles located in the direction of travel of the vehicle V. Also, for example, the brake control unit 223 causes the brake drive device 63 to apply braking to avoid collision with people or objects located in the direction of travel of the vehicle V or around the vehicle V. Also, for example, the brake control unit 223 causes the brake drive device 63 to maintain the stopped state of the vehicle V while the vehicle V is stopped.

The driving control unit 224 controls the throttle control device 64 to realize the acceleration control function included in the autonomous driving function of the vehicle V. For example, the driving control unit 224 causes the throttle control device 64 to maintain an appropriate driving speed of the vehicle V.

In this way, the autonomous driving control unit 220 included in the emergency important load 22 controls the functional units of the vehicle V to cause the vehicle V to perform autonomous driving. The autonomous driving of the vehicle V includes at least the lane keeping function performed by the lane keeping control unit 221 and the steering control unit 222. Furthermore, the autonomous driving of the vehicle V may also include control to stop the vehicle V at a safe position on the road in the event of a so-called emergency.

2. Vehicle Power Supply System Operation
The operation of the vehicle power supply system 1 will now be described.
3 and 4 are flowcharts showing the operation of the vehicle power supply system 1. Fig. 3 shows the operation when the vehicle V starts autonomous driving, and Fig. 4 shows the operation while the vehicle V is performing autonomous driving. In this embodiment, an example will be described in which the backup power supply control device 25 performs the operations shown in Figs. 3 and 4 as described above, but there is no limitation to the ECU 50 or another control device performing these operations.

The backup power supply control device 25 detects a trigger that causes the ECU 50 to start autonomous driving (step S11). Step S11, for example, involves outputting a signal to the backup power supply control device 25 notifying the ECU 50 that it will start autonomous driving.

The backup power supply control device 25 performs an estimation process to estimate the available power that the backup low-voltage power supply 23 can supply to the emergency critical load 22 (step S12). The backup power supply control device 25 compares the estimated value obtained in the estimation process with a first threshold value and determines whether the estimated value is equal to or less than the first threshold value (step S13).

If it is determined that the estimated value is less than or equal to the first threshold value (step S13; YES), the backup power supply control device 25 outputs a signal indicating that autonomous driving is prohibited, i.e., a prohibition signal, to the ECU 50 (step S14), and terminates this processing. If it is determined that the estimated value is not less than or equal to the first threshold value (step S13; NO), the backup power supply control device 25 outputs a signal indicating that autonomous driving is permitted, i.e., a permission signal, to the ECU 50 (step S15), and terminates this processing.

3, the ECU 50 can start autonomous driving of the vehicle V when the backup low-voltage power supply 23 can supply sufficient power.
In addition, the backup power supply control device 25 may perform the operation of Figure 3 at a predetermined period when the vehicle V is not executing the autonomous driving mode and no trigger for starting the autonomous driving mode has occurred.

In FIG. 4, the backup power supply control device 25 determines whether the vehicle V is performing autonomous driving (step S21). If the vehicle V is not performing autonomous driving (step S21; NO), the backup power supply control device 25 waits.

If the vehicle V is performing autonomous driving (step S21; YES), the backup power supply control device 25 performs estimation processing (step S22). The backup power supply control device 25 compares the estimated value obtained in the estimation processing with a second threshold value and determines whether the estimated value is less than the second threshold value (step S23).

If it is determined that the estimated value is less than the second threshold value (step S23; YES), the backup power supply control device 25 outputs a signal indicating that autonomous driving is prohibited, i.e., a prohibition signal, to the ECU 50 (step S24), and ends this processing. The prohibition signal output by the backup power supply control device 25 in step S24 is a signal indicating that continuation of autonomous driving is prohibited.

If it is determined that the estimated value is not less than the second threshold (step S23; NO), the backup power supply control device 25 determines whether the estimated value is less than or equal to the third threshold (step S25).

If it is determined that the estimated value is equal to or less than the third threshold (step S23; YES), the backup power supply control device 25 outputs a signal instructing the high-voltage power supply unit 36 to operate in high-voltage mode to charge the backup low-voltage power supply 23 (step S26). This causes the ECU 50 to control the high-voltage power supply 31 and/or the step-down device 40 to operate the high-voltage power supply unit 36 in high-voltage mode. The ECU 50 or backup power supply control device 25 also turns on the second switch SW2 to connect the high-voltage power supply unit 36 to the backup low-voltage power supply 23. This causes the backup low-voltage power supply 23 to be charged with high-voltage power output by the high-voltage power supply unit 36.

The backup power supply control device 25 then outputs a signal to the ECU 50 indicating that autonomous driving of the vehicle V is permitted (step S27), and this processing ends. The prohibition signal output by the backup power supply control device 25 in step S27 is a signal indicating that continuation of autonomous driving is permitted.

If it is determined that the estimated value is not less than the third threshold value (step S23; NO), the backup power supply control device 25 proceeds to step S27.

FIG. 5 is a timing chart showing the operation of the vehicle power supply system 1.
Figure 5(a) shows the operating modes of vehicle V, Figure 5(b) shows the operating modes of high-voltage power supply unit 36, and Figure 5(c) shows the control of high-voltage power supply unit 36 by ECU 50. Figure 5(d) shows the state of backup power supply system 20. Figure 5(e) is a graph showing the available power supply estimated by backup power supply control device 25, with the vertical axis representing the available power supply or amount of power and the horizontal axis representing time. Figure 5(e) shows a first threshold value TH1, a second threshold value TH2, and a third threshold value TH3.

In this embodiment, the third threshold TH3 is the same as or lower than the first threshold TH1. The second threshold TH2 is lower than the third threshold TH3. The first threshold TH1 is a threshold related to the amount of power or electricity determined based on the amount of power required to operate the emergency important load 22 when the vehicle V is operating autonomously in the autonomous driving mode.

At time T1, vehicle V is traveling in normal traveling mode. At this time, the power that can be supplied by backup low-voltage power supply 23 is lower than first threshold value TH1. Therefore, backup power supply control device 25 does not determine that backup power supply from backup low-voltage power supply 23 is possible, and continues monitoring the status. ECU 50 instructs high-voltage power supply unit 36 to perform high-voltage charging, and high-voltage power supply unit 36 is supplying power in high-voltage mode.

When high-voltage charging is performed, the power that can be supplied by the backup low-voltage power supply 23 is restored. In the example of Figure 5, the power that can be supplied exceeds the first threshold value TH1 at time T2. In this case, the backup power supply control device 25 determines that backup power supply is possible at time T2. The ECU 50 instructs the high-voltage power supply unit 36 to perform low-voltage charging. Low-voltage charging means charging the backup low-voltage power supply 23 with power output by the high-voltage power supply unit 36 in normal operation mode. In accordance with this instruction, the high-voltage power supply unit 36 supplies power in normal operation mode.

Assume that a trigger to start autonomous driving of vehicle V occurs at time T3. Here, the backup power supply control device 25 outputs a signal indicating that autonomous driving is permitted, because the available power supply at time T3 is higher than the first threshold TH1. ECU 50 starts the autonomous driving mode of vehicle V in accordance with the signal output by backup power supply control device 25.

In the example of FIG. 5, the available power supply of the backup low-voltage power supply 23 decreases after time T3 due to some factor. In this example, at time T4, the estimated available power supply becomes lower than the third threshold value TH3 but higher than the second threshold value TH2. In this case, at time T4, the backup power supply control device 25 outputs a signal instructing charging in high-voltage mode by the operation of step S26. In response to this signal, the ECU 50 instructs the high-voltage power supply unit 36 to perform high-voltage charging. This instruction is issued, for example, at time T5. In accordance with the instruction from the ECU 50, the high-voltage power supply unit 36 executes high-voltage mode. This starts high-voltage charging of the backup low-voltage power supply 23, allowing the vehicle V to continue in autonomous driving mode.

3. Other Embodiments
The above embodiment shows a specific example to which the present invention is applied, and does not limit the form to which the invention is applied.

For example, the method by which the backup power supply control device 25 estimates the available power supply of the backup low-voltage power supply 23 is not limited to the method described above. For example, if the backup low-voltage power supply 23 is equipped with a power supply control device that manages and controls charging and discharging to the backup low-voltage power supply 23, the available power supply may be estimated by the power supply control device continuously or at predetermined time intervals. In this case, the backup power supply control device 25 may obtain an estimated value of the available power supply from the power supply control device of the backup low-voltage power supply 23.

The configuration shown in Figure 1 is one example; for example, the step-down device 40 may be integrated with the high-voltage power supply 31, and power boosted or increased in voltage by the step-down device 40 may be supplied to the high-voltage load 32. Furthermore, the timing chart shown in Figure 5 is merely one example of operation, and the operation of the vehicle power supply system 1 can be modified as appropriate.

4. Configurations supported by the above embodiment
The above embodiment supports the following configurations.

(Configuration 1) A vehicle power supply system is mounted on a vehicle capable of at least partial autonomous driving in an autonomous driving mode that allows at least the driver to be exempt from steering operation, and includes: a main power supply system having a main low-voltage power supply and a normal load; a backup power supply system having a backup low-voltage power supply and an important emergency load and connected to the main power supply system; and a high-voltage power supply unit capable of outputting a voltage higher than a rated voltage of the backup power supply system, wherein the backup power supply system has a backup power supply control device that monitors the state of the backup low-voltage power supply and controls input and output of power from the backup low-voltage power supply, and the backup power supply control device is capable of executing an estimation process to estimate a suppliable power indicating the amount of power or power that can be supplied from the backup low-voltage power supply to the important emergency load, and when the vehicle is not autonomously driving in the autonomous driving mode, the backup power supply control device executes the estimation process, and if the suppliable power estimated by the estimation process is equal to or greater than a first threshold value, when the available power supply estimated by the estimation process is less than a third threshold, the backup power supply control device outputs a signal indicating that the vehicle is permitted to continue in the autonomous driving mode and that the backup low-voltage power supply is permitted to charge with power generated by the high-voltage power supply unit, and the first threshold is a threshold related to an amount of power or power determined based on an amount of power required to operate the emergency important load when the vehicle is autonomously driving in the autonomous driving mode.
According to configuration 1, the autonomous driving mode is avoided when the backup low-voltage power supply's available power is low, and while the autonomous driving mode is being executed, the autonomous driving mode can be continued by charging even if the available power supply of the backup low-voltage power supply decreases. This allows a vehicle that is at least partially capable of autonomous driving to continue autonomous driving even if the available power supply of the backup low-voltage power supply decreases. Therefore, it is possible to prevent a decrease in opportunities to use autonomous driving due to the supply of power to loads related to autonomous driving. This increases the opportunities and time that the vehicle can execute autonomous driving, thereby improving marketability.

(Configuration 2) The vehicle power supply system according to configuration 1, wherein the third threshold is a value indicating an amount of electric power or power equal to or less than the first threshold and is a value indicating an amount of electric power or power greater than the second threshold.
According to configuration 2, a minimum state is maintained in which power can be supplied from the backup low-voltage power supply to important loads in an emergency while the autonomous operation mode is being executed, and it is possible to prevent a decrease in opportunities to use autonomous operation due to the supply of power to loads related to autonomous operation.

(Configuration 3) The vehicle power supply system according to Configuration 1 or 2, wherein the high-voltage power supply unit is capable of operating in a high-voltage mode in which it outputs power at a voltage higher than a rated voltage of the backup power supply system, and a normal voltage mode in which it outputs power at a voltage lower than that in the high-voltage mode, and wherein the backup power supply control device outputs a signal indicating that it is permitted for the high-voltage power supply unit to charge the backup low-voltage power supply with power generated in the high-voltage mode when the available power supply estimated in the estimation process is equal to or less than a third threshold.
According to the third aspect, when the available power supply of the backup low-voltage power supply drops while the autonomous operation mode is being executed, the available power supply can be restored in a shorter time.

1...vehicle power supply system, 10...power supply system, 11...main low-voltage power supply, 12...normal load, 20...backup power supply system, 21...backup power supply unit, 22...critical emergency load, 23...backup low-voltage power supply, 24...switching device, 25...backup power supply control device, 30...high-voltage power supply system, 31...high-voltage power supply, 32...high-voltage load, 36...high-voltage power supply section, 40...step-down device, 50...ECU, 55...operation section, 56...SSSW, 241...switch module, 321...drive unit, 322...air conditioning unit, CP...capacitor, MG...rotating electric machine, PCU...power control unit, SW1...first switch, SW2...second switch, SW3...third switch, V...vehicle.

Claims (2)

A vehicle power supply system is mounted on a vehicle capable of at least partial autonomous driving in an autonomous driving mode that allows and executes the autonomous driving operation by at least a driver, and includes: a main power supply system having a main low-voltage power supply and a normal load; a backup power supply system having a backup low-voltage power supply and an important emergency load and connected to the main power supply system; and a high-voltage power supply unit capable of outputting a voltage higher than the rated voltage of the backup power supply system,
The backup power supply system includes:
a backup power supply control device that monitors the state of the backup low-voltage power supply and controls input and output of power from the backup low-voltage power supply;
the backup power supply control device is capable of executing an estimation process to estimate a supplyable power indicating an amount of power or power that can be supplied from the backup low-voltage power supply to the emergency important load,
When the vehicle is not autonomously driving in the autonomous driving mode, the backup power supply control device
Execute the estimation process,
If the available power supply estimated in the estimation process is equal to or greater than a first threshold, outputting a signal indicating that the vehicle is permitted to autonomously drive in the autonomous driving mode;
When the available power supply estimated in the estimation process is equal to or less than a third threshold, a signal indicating that the vehicle is permitted to autonomously drive in the autonomous driving mode is not output,
When the vehicle is autonomously driving in the autonomous driving mode, the backup power supply control device
Execute the estimation process,
If the available power supply estimated in the estimation process is less than a second threshold, outputting a signal indicating that the vehicle is prohibited from autonomously driving in the autonomous driving mode;
When the vehicle is autonomously driving in the autonomous driving mode, the backup power supply control device
Execute the estimation process,
when the suppliable power estimated in the estimation process is equal to or less than a third threshold, outputting a signal indicating that the vehicle is permitted to continue in the autonomous driving mode and that the backup low-voltage power supply is permitted to be charged with the power generated by the high-voltage power supply unit;
the first threshold is a threshold related to an amount of power or power that is determined in advance based on an amount of power required to operate the emergency important load when the vehicle is autonomously driving in the autonomous driving mode,
the second threshold is a predetermined value lower than the third threshold,
The third threshold is a predetermined value indicating an amount of electric power or power equal to or less than the first threshold, and is a value indicating an amount of electric power or power greater than the second threshold. the high-voltage power supply unit is capable of executing a high-voltage mode in which power is output at a voltage higher than a rated voltage of the backup power supply system, and a normal voltage mode in which power is output at a voltage lower than that of the high-voltage mode;
2. The vehicle power supply system according to claim 1, wherein, when the available power supply estimated in the estimation process is equal to or less than a third threshold, the backup power supply control device outputs a signal indicating that the high-voltage power supply unit is permitted to charge the backup low-voltage power supply with power generated in the high-voltage mode.