JP7769596B2 - 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.

In vehicles equipped with functional units that function to ensure traffic safety, such as autonomous driving, it is important to stabilize the power supply to these functional units. For this reason, technologies have been proposed for accurately monitoring the state of a vehicle's power supply. For example, Patent Document 1 discloses technology for determining the state of battery degradation by estimating the state of charge of the vehicle's battery.

Japanese Patent Application Laid-Open No. 2019-152551

Technologies for estimating the state of a battery installed in a vehicle are easily affected by the state of the vehicle. For example, the technology described in Patent Document 1 estimates the state of charge on the condition that the battery temperature is lower than a threshold. As such, there is a problem in that it is difficult to accurately estimate or determine the state of the battery depending on the state of the vehicle. For this reason, situations may arise where it is not possible to confirm that there are no problems with the battery state, which has been a challenge when implementing functional units for ensuring traffic safety in vehicles.
In order to solve the above problems, the present application aims to estimate the state of the power source that supplies power to a functional unit in a vehicle equipped with a functional unit that functions to ensure traffic safety, such as autonomous driving, using a method that is less affected by the state of the vehicle, thereby contributing to the development of a sustainable transportation system.

One aspect for achieving the above object is a vehicle power supply system configured by mounting on a vehicle a first power supply system having a first low-voltage power supply and a first power load, a second power supply system having a second low-voltage power supply and a second power load and connected to the first power supply system, and a high-voltage power supply unit capable of outputting a voltage higher than a rated voltage of the first power supply system or the second power supply system, wherein the second power supply system has a switching device capable of switching between a state in which the second low-voltage power supply is connected to the first power supply system so as to be able to supply power from the second low-voltage power supply to the first power supply system, and a state in which the second low-voltage power supply is disconnected from the first power supply system, and a vehicle power supply control device that controls the switching device, and the vehicle power supply control device performs an estimation process that measures an internal resistance of the second low-voltage power supply and estimates whether the second low-voltage power supply is in a deteriorated state. and a vehicle power supply system capable of outputting a signal indicating whether the second low-voltage power supply is in a deteriorated state based on an estimation result of the estimation process, and capable of executing, as the estimation process, a first estimation process that performs estimation by measuring an internal resistance of the second low-voltage power supply when the second low-voltage power supply is being charged, and a second estimation process that performs estimation based on discharge power from the second low-voltage power supply, wherein the second estimation process is executed when the high-voltage power supply unit of the vehicle power supply system is in an on-state, power is being supplied from the high-voltage power supply unit to the first power supply system , and the state of the vehicle satisfies predetermined conditions, wherein the predetermined conditions include the temperature of the second low-voltage power supply being equal to or lower than a first temperature threshold that indicates an extremely low temperature that is unsuitable for measuring an internal resistance value by charging .
A second aspect for achieving the above object is a vehicle power supply system comprising a first power supply system having a first low-voltage power supply and a first power load, a second power supply system having a second low-voltage power supply and a second power load and connected to the first power supply system, and a high-voltage power supply unit capable of outputting a voltage higher than a rated voltage of the first power supply system or the second power supply system, the second power supply system having a switching device capable of switching between a state in which the second low-voltage power supply is connected to the first power supply system so as to be able to supply power from the second low-voltage power supply to the first power supply system, and a state in which the second low-voltage power supply is disconnected from the first power supply system, and a vehicle power supply control device that controls the switching device, and the vehicle power supply control device having an estimation device that measures an internal resistance of the second low-voltage power supply to estimate whether the second low-voltage power supply is in a deteriorated state. and is capable of executing a process to output a signal indicating whether the second low-voltage power supply is in a deteriorated state based on an estimation result of the estimation process, and is capable of executing, as the estimation process, a first estimation process that performs estimation by measuring an internal resistance of the second low-voltage power supply when the second low-voltage power supply is being charged, and a second estimation process that performs estimation based on discharge power from the second low-voltage power supply, and is configured to execute the second estimation process when the high-voltage power supply unit of the vehicle power supply system is in an on state, power is being supplied from the high-voltage power supply unit to the first power supply system, and the state of the vehicle satisfies predetermined conditions, the predetermined conditions including the temperature of the second low-voltage power supply being equal to or higher than a second temperature threshold that indicates a temperature too high to be suitable for charging.
A third aspect for achieving the above object is a vehicle power supply system comprising a first power supply system having a first low-voltage power supply and a first power load, a second power supply system having a second low-voltage power supply and a second power load and connected to the first power supply system, and a high-voltage power supply unit capable of outputting a voltage higher than a rated voltage of the first power supply system or the second power supply system, the second power supply system having a switching device capable of switching between a state in which the second low-voltage power supply is connected to the first power supply system so as to be able to supply power from the second low-voltage power supply to the first power supply system and a state in which the second low-voltage power supply is disconnected from the first power supply system, and a vehicle power supply control device that controls the switching device, the vehicle power supply control device performing an estimation process for measuring an internal resistance of the second low-voltage power supply to estimate whether the second low-voltage power supply is in a deteriorated state, and determining whether the second low-voltage power supply is in a deteriorated state based on an estimation result of the estimation process. and a vehicle power supply system capable of outputting a signal indicating whether the second low-voltage power supply is in a deteriorated state, and capable of executing, as the estimation processes, a first estimation process that performs estimation by measuring an internal resistance of the second low-voltage power supply when the second low-voltage power supply is being charged, and a second estimation process that performs estimation based on discharge power from the second low-voltage power supply, wherein the second estimation process is executed when the high-voltage power supply unit of the vehicle power supply system is in an on-state, is in a state where power is being supplied from the high-voltage power supply unit to the first power supply system, and the state of the vehicle satisfies a predetermined condition, wherein the first low-voltage power supply and the second low-voltage power supply are constituted by batteries that can be charged and discharged, and the predetermined condition includes a remaining capacity of the battery of the first low-voltage power supply being smaller than the remaining capacity of the battery of the second low-voltage power supply.

With the above configuration, the degradation state of the second low-voltage power supply capable of supplying power to the first power load and the second power load can be estimated with high accuracy using a method that is less affected by the state of the vehicle.

1 is a schematic diagram of a vehicle power supply system according to an embodiment; FIG. 3 is an explanatory diagram of an estimation process in the vehicle power supply system. FIG. 3 is an explanatory diagram of an estimation process in the vehicle power supply system. 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. FIG. 10 is an explanatory diagram showing an example of execution timing of a state detection operation.

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 a function of managing the main low-voltage power supply 11 and the backup low-voltage power supply 23. In the vehicle power supply system 1, a charge/discharge management device (not shown) may be attached to the main low-voltage power supply 11. In this case, the backup power supply control device 25 may execute the management function for the main low-voltage power supply 11 by acquiring information from the charge/discharge management device. Similarly, a charge/discharge management device (not shown) may be attached to the backup low-voltage power supply 23, and the backup power supply control device 25 may execute the management function for the backup low-voltage power supply 23 by acquiring information from the charge/discharge management device.
In this embodiment, a configuration will be described in which the backup power supply control device 25 is directly connected to the main low-voltage power supply 11 and the backup low-voltage power supply 23.

The backup power supply control device 25 acquires the remaining capacity of the main low-voltage power supply 11. The backup power supply control device 25 may have the full charge capacity (FCC: Full Charge Capacity) of the main low-voltage power supply 11. In this case, the backup power supply control device 25 may calculate the state of charge (SOC: State of Charge) of the main low-voltage power supply 11 based on the actual remaining capacity (RM: Remaining Capacity) of the main low-voltage power supply 11 and the full charge capacity. The backup power supply control device 25 may calculate the remaining capacity of the main low-voltage power supply 11, for example, by detecting the voltage across the backup low-voltage power supply 23. The backup power supply control device 25 may also calculate the remaining capacity of the main low-voltage power supply 11 by counting the current input and output to and from the main low-voltage power supply 11. The backup power supply control device 25 may use the above-mentioned charge/discharge management device in the process of calculating the remaining capacity of the main low-voltage power supply 11.

The backup power supply control device 25 has the functions of estimating the degradation state of the backup low-voltage power supply 23, detecting the temperature of the backup low-voltage power supply 23, and calculating the remaining capacity of the backup low-voltage power supply 23. The remaining capacity may be the actual remaining capacity (RM) of the backup low-voltage power supply 23 or the state of charge (SOC). The backup power supply control device 25 may also have the full charge capacity (FCC) of the backup low-voltage power supply 23, in which case the backup power supply control device 25 may calculate the state of charge based on the actual remaining capacity and full charge capacity of the backup low-voltage power supply 23.

The backup power supply control device 25 calculates the remaining 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 calculate the remaining 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 use the above-mentioned charge/discharge management device in the process of calculating the remaining capacity of the backup low-voltage power supply 23. The backup power supply control device 25 also acquires the temperature of the backup low-voltage power supply 23 from a temperature detection device installed in the backup low-voltage power supply 23 or the above-mentioned charge/discharge management device.

The process by which the backup power supply control device 25 estimates the degradation state of the backup low-voltage power supply 23 is called the estimation process. Various known methods can be used to estimate or detect the degradation state of the backup low-voltage power supply 23. In this embodiment, the estimation process performed by the backup power supply control device 25 includes, as an example, a first estimation process in which the backup power supply control device 25 estimates the degradation state by taking measurements when the backup low-voltage power supply 23 is being charged, and a second estimation process in which the backup low-voltage power supply 23 is being discharged.

The first estimation process and the second estimation process are, for example, methods of measuring the internal resistance value of the backup low-voltage power supply 23 and estimating the degradation state of the backup low-voltage power supply 23 based on the measured internal resistance value. The first estimation process may be a process of correcting the degradation state by combining the internal resistance value of the backup low-voltage power supply 23 with one or more other pieces of information. Examples of other information include the remaining capacity, state of charge, temperature, cumulative usage time, previously measured internal resistance values, and usage time since the internal resistance value was previously measured for the backup low-voltage power supply 23, but other information may also be used.

In the first estimation process, the backup power supply control device 25 measures the internal resistance of the backup low-voltage power supply 23 while the backup low-voltage power supply 23 is being charged. In the second estimation process, the backup power supply control device 25 measures the internal resistance of the backup low-voltage power supply 23 using the discharge power of the backup low-voltage power supply 23 while the backup low-voltage power supply 23 is being discharged. The backup power supply control device 25 selects whether to execute the first charge/discharge capability estimation process or the second estimation process based on its own judgment or in accordance with instructions from the ECU 50.

In the above configuration, the main low-voltage power supply 11 corresponds to an example of a first low-voltage power supply, the normal load 12 corresponds to an example of a first power load, and the main power supply system 10 corresponds to an example of a first power supply system. The backup low-voltage power supply 23 corresponds to an example of a second low-voltage power supply, the important emergency load 22 corresponds to an example of a second power load, and the backup power supply system 20 corresponds to an example of a second power supply system. The backup power supply control device 25 corresponds to an example of a vehicle power supply control device. The main low-voltage power supply 11 and the backup low-voltage power supply 23 are chargeable and dischargeable batteries as described above.

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.

Furthermore, when the switching device 24 turns on the first switch SW1 or the third switch SW3, the backup power supply system 20 is connected to the main power supply system 10 so that power can be supplied from the backup low-voltage power supply 23 to the main power supply system 10. Therefore, it is possible to operate the normal load 12 using power from the backup low-voltage power supply 23.

[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 may be capable of operating in a normal operation mode and a high-voltage mode. In this case, the high-voltage power supply unit 36 switches between the normal operation mode and the high-voltage mode 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 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 charge state of the backup low-voltage power supply 23 in a shorter time than when the backup low-voltage power supply 23 is charged in normal operation mode. In other words, high-voltage charging refers to an operation in which the high-voltage power supply unit 36 operates in high-voltage mode to quickly charge the backup low-voltage power supply 23. In 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 normal operation mode.

The vehicle power supply system 1 may charge the main low-voltage power supply 11, as well as the backup low-voltage power supply 23, with power output by the high-voltage power supply unit 36. In this case, if the voltage output by the high-voltage power supply unit 36 is higher than the output voltage of the main low-voltage power supply 11, charging of the main low-voltage power supply 11 is performed. If the high-voltage power supply 31 is equipped with a battery that supports high-voltage charging, the vehicle power supply system 1 may operate the high-voltage power supply unit 36 in high-voltage mode to perform high-voltage charging of the main low-voltage power supply 11 as well as the backup low-voltage power supply 23.

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 estimates the deterioration state of the backup low-voltage power supply 23 via the backup power supply control device 25. The backup power supply control device 25 outputs a signal based on the deterioration state of the backup low-voltage power supply 23.

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, or 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, 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, such as determining whether the state of the backup low-voltage power supply 23 is sufficient to achieve a minimal-risk maneuver. In each process, including this determination, the backup power supply control device 25 references various thresholds, as described below. 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 deterioration state of the backup low-voltage power supply 23 is not appropriate, it outputs a signal indicating that autonomous driving of the vehicle V is prohibited. This signal can 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 ECU 50 starts autonomous driving of vehicle V, it does so on the condition that an permission signal has been input from backup power supply control device 25. Furthermore, if an permission 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 permission signal has been input from backup power supply control device 25 at predetermined time intervals, and terminates autonomous driving if a state in which an permission signal has not been input continues for a predetermined time or longer.

2. Vehicle Power Supply System Operation
The operation of the vehicle power supply system 1 will now be described.
2 and 3 are explanatory diagrams of estimation processes in the vehicle power supply system 1. Fig. 2 shows a first estimation process, and Fig. 3 shows a second estimation process. Figs. 2 and 3 show a schematic diagram of the connection state of the main parts that make up the vehicle power supply system 1.

In the state shown in FIG. 2, the switching device 24 is on, and the backup power system 20 is connected to the high-voltage power supply unit 36. Specifically, the backup power supply control device 25 has turned on at least one of the first switch SW1 and the third switch SW3 of the switching device 24. In particular, it is appropriate that the first switch SW1, which has a large current capacity, is turned on. In addition, the second switch SW2 is on, and the backup low-voltage power supply 23 is connected to the switching device 24. In this state, power output by the high-voltage power supply unit 36 is supplied to the emergency important load 22. In addition, the main low-voltage power supply 11 and the backup low-voltage power supply 23 are charged with power supplied by the high-voltage power supply unit 36.

In the first estimation process, the backup power supply control device 25 measures or acquires the internal resistance value of the backup low-voltage power supply 23 while the backup low-voltage power supply 23 is being charged by the high-voltage power supply unit 36. The backup power supply control device 25 estimates the degradation state of the backup low-voltage power supply 23 based on the internal resistance value of the backup low-voltage power supply 23.

In the state shown in FIG. 3, the switching device 24 is off, and the backup power system 20 and the high-voltage power supply unit 36 are disconnected. Specifically, the backup power supply control device 25 has both the first switch SW1 and the third switch SW3 of the switching device 24 turned off. In this state, power is not supplied from the high-voltage power supply unit 36 to the emergency important load 22 or the backup low-voltage power supply 23. Therefore, when the emergency important load 22 consumes power in the state shown in FIG. 3, power is supplied to the emergency important load 22 from the backup low-voltage power supply 23.

In the second estimation process, the backup power supply control device 25 measures or acquires the internal resistance value of the backup low-voltage power supply 23 when the backup low-voltage power supply 23 is discharging. The backup power supply control device 25 estimates the degradation state of the backup low-voltage power supply 23 based on the internal resistance value of the backup low-voltage power supply 23.

The first estimation process is characterized by its accuracy decreasing depending on the state of the vehicle V and the environment. For example, if the temperature of the backup low-voltage power supply 23 is low, the internal resistance value of the backup low-voltage power supply 23 increases, making it necessary to charge the backup low-voltage power supply 23 at a high voltage. If the temperature of the backup low-voltage power supply 23 is extremely low, the charging voltage of the backup low-voltage power supply 23 will increase to the point where it reaches the upper limit of the voltage that the backup low-voltage power supply 23 can tolerate, which may decrease the accuracy of detecting the internal resistance value.

Furthermore, for example, if the remaining capacity of the main low-voltage power supply 11 is smaller than the remaining capacity of the backup low-voltage power supply 23, much of the power supplied by the high-voltage power supply unit 36 will be used to charge the main low-voltage power supply 11, making it difficult to charge the backup low-voltage power supply 23. As a result, there is a possibility that the internal resistance value of the backup low-voltage power supply 23 will not be detected accurately during charging.

Furthermore, the temperature of the backup low-voltage power supply 23 tends to rise when it is being charged. To protect the backup low-voltage power supply 23, it is desirable not to charge it when the temperature of the backup low-voltage power supply 23 is higher than a predetermined temperature.

As such, depending on the state of the vehicle V, the accuracy of the first estimation process may be reduced, or the first estimation process may not be necessary. In such cases, the vehicle power supply system 1 estimates the degradation state of the backup low-voltage power supply 23 by performing the second estimation process.

Figures 4 and 5 are flowcharts showing the operation of the vehicle power supply system 1. In this embodiment, the operations shown in Figures 4 and 5 are performed by the backup power supply control device 25.

FIG. 4 shows a state detection operation including the backup power supply control device 25 estimating the deterioration state of the backup low-voltage power supply 23 .
The backup power supply control device 25 executes estimation processing at a predetermined timing (step S11), which will be described later with reference to FIG.
The backup power supply control device 25 determines whether the estimated value of the degradation state of the backup low-voltage power supply 23 obtained by the estimation process is equal to or less than a first threshold value (step S12). The estimated value of the degradation state of the backup low-voltage power supply 23 can be considered an estimation result. If the estimated value is equal to or less than the first threshold value, it means that the degradation state of the backup low-voltage power supply 23 is lower than an appropriate range, and it can be said that the degradation of the backup low-voltage power supply 23 is progressing.

If it is determined that the estimated value of the degradation state is equal to or less than the first threshold value (step S12; YES), the backup power supply control device 25 outputs a signal indicating that the backup low-voltage power supply 23 is in a degradation state to the ECU 50 (step S13). In step S13, the backup power supply control device 25 may output a signal indicating that autonomous driving is not permitted to the ECU 50.

If it is determined that the estimated value of the degradation state is not equal to or less than the first threshold value (step S12; NO), the backup power supply control device 25 outputs a signal to the ECU 50 indicating that the backup low-voltage power supply 23 is not in a degradation state (step S14). In step S14, the backup power supply control device 25 may output a signal to the ECU 50 indicating that autonomous driving is permitted.

Figure 5 shows in detail step S11 of Figure 4. In the operations described below, the first temperature threshold corresponds to the first temperature, and the second temperature threshold corresponds to the second temperature.
The backup power supply control device 25 determines whether the high-voltage power supply unit 36 is outputting power (step S21). The state in which the high-voltage power supply unit 36 is outputting power means that the vehicle V is running. If it is determined that the high-voltage power supply unit 36 is not outputting power (step S21; NO), the backup power supply control device 25 ends the operations shown in FIGS. 4 and 5.

If it is determined that the high-voltage power supply unit 36 is outputting power (step S21; YES), the backup power supply control device 25 determines whether the main low-voltage power supply 11 is charging (step S22). If it is determined that the main low-voltage power supply 11 is charging (step S22; YES), the backup power supply control device 25 selects and executes the second estimation process (step S23). If the first estimation process is executed while the main low-voltage power supply 11 is charging, the charging current to the backup low-voltage power supply 23 may be insufficient, which may affect the accuracy of measuring the internal resistance value. For this reason, it is appropriate to execute the second estimation process.

In step S23, the backup power supply control device 25 switches off the first switch SW1 and the third switch SW3 of the switching device 24, operates the emergency important load 22, and measures the internal resistance value of the backup low-voltage power supply 23 while the emergency important load 22 is operating. The ECU 50 may control the operation of the emergency important load 22 in step S23. After the internal resistance value is obtained, the backup power supply control device 25 returns to the operation shown in FIG. 4.

If it is determined that the main low-voltage power supply 11 is not charging (step S22; NO), the backup power supply control device 25 acquires the temperature TB of the backup low-voltage power supply 23 (step S24). The backup power supply control device 25 determines whether the temperature TB is equal to or lower than the first temperature threshold (step S25). If it is determined that the temperature TB is equal to or lower than the first temperature threshold (step S25; YES), the backup power supply control device 25 proceeds to step S23 and executes the second estimation process. The first temperature threshold is a threshold that indicates an extremely low temperature that is not suitable for measuring the internal resistance value due to charging, and is, for example, -15°C.

If it is determined that temperature TB is not equal to or less than the first temperature threshold (step S25; NO), the backup power supply control device 25 determines whether temperature TB is equal to or greater than the second temperature threshold (step S26). If it is determined that temperature TB is equal to or greater than the second temperature threshold (step S26; YES), the backup power supply control device 25 proceeds to step S23 and executes the second estimation process. The second temperature threshold is a threshold that indicates a temperature too high to be suitable for charging, and is, for example, 40°C.

If it is determined that the temperature TB is not equal to or greater than the second temperature threshold (step S26; NO), the backup power supply control device 25 acquires the remaining capacity (here, RMA) of the main low-voltage power supply 11 and the remaining capacity (here, RMB) of the backup low-voltage power supply (step S27). The backup power supply control device 25 determines whether the remaining capacity RMA is smaller than the remaining capacity RMB (step S28). The remaining capacities RMA and RMB may be the state of charge SOC calculated from the remaining capacities.

If it is determined that the remaining capacity RMA is less than the remaining capacity RMB (step S28; YES), the backup power supply control device 25 proceeds to step S23 and performs the second estimation process. The remaining capacity of the main low-voltage power supply 11 may decrease, for example, if the vehicle V has not been used for a relatively long period of time. If the first estimation process is performed when the remaining capacity of the main low-voltage power supply 11 is less than the remaining capacity of the backup low-voltage power supply 23, there is a possibility that sufficient power to charge the backup low-voltage power supply 23 will not be supplied to the backup low-voltage power supply 23, so it is preferable to perform the second estimation process.

If it is determined that the remaining capacity RMA is not less than the remaining capacity RMB (step S28; NO), the backup power supply control device 25 proceeds to step S29 and executes a first estimation process (step S29). In step S29, the backup power supply control device 25 switches on the first switch SW1 of the switching device 24 and measures the internal resistance of the backup low-voltage power supply 23 while it is being charged from the high-voltage power supply unit 36 to the backup low-voltage power supply 23. After the internal resistance value is obtained, the backup power supply control device 25 returns to the operation shown in FIG. 4.

Figure 6 is an explanatory diagram showing an example of the execution timing of the state detection operation, with the horizontal axis representing the passage of time. Figure 6(a) shows the operating state of the vehicle V, Figure 6(b) shows the state of the high-voltage power supply unit 36, and Figure 6(c) shows the state of the backup power supply system 20.

Time T1 is the timing at which, while vehicle V is stopped, an operation performed by the user of vehicle V prior to starting vehicle V is detected. This operation may be, for example, unlocking the doors of vehicle V or operating a remote control for vehicle V.

The high-voltage power supply unit 36 stops supplying power when the vehicle V is stopped. At time T1, the high-voltage power supply unit 36 performs preemptive operation under the control of the ECU 50. Preemptive operation means that the high-voltage power supply unit 36 starts up and supplies power before the normal load 12 or the emergency important load 22 starts operating. Preemptive operation of the high-voltage power supply unit 36 is performed, for example, under the control of the ECU 50 or the backup power supply control device 25.

Next, at time T2, when the vehicle power supply system 1 detects that the SSSW 56 has been operated, it transitions the vehicle V to an ignition-on state. In a vehicle V that does not have an internal combustion engine, the vehicle V transitions to a ready state at time T2. The ready state is a state in which the vehicle V is ready to run. When the vehicle V is in the ignition-on or ready state, it runs in response to user operation. At time T2, the vehicle power supply system 1 supplies power to each component via the high-voltage power supply unit 36.

When the vehicle power supply system 1 detects that the user has operated the SSSW 56 while the ignition is on or in the Ready state, it stops the vehicle V. Here, the vehicle power supply system 1 causes the high-voltage power supply unit 36 to execute extended operation. Extended operation means that the high-voltage power supply unit 36 continues to supply power for a predetermined period of time after the vehicle V has stopped. The length of time for extended operation is set in advance, and the vehicle power supply system 1 ends the extended operation at time T4 and stops the high-voltage power supply unit 36.

The status detection operation by the vehicle power supply system 1 is performed, for example, between time T1 and time T2 and/or between time T3 and time T4. After time T2, a large amount of current is supplied to the normal load 12 and the emergency important load 22, so there is a possibility that a sufficient current cannot be secured to charge the backup low-voltage power supply 23. In contrast, if the status detection operation is performed between time T1 and time T2, a sufficient charging current can be secured, allowing the deterioration state of the backup low-voltage power supply 23 to be estimated with high accuracy. Furthermore, performing the status detection operation before driving the vehicle V has the advantage of being able to estimate the deterioration state of the backup low-voltage power supply 23 before autonomous driving begins and provide information to the user as needed.

Furthermore, for example, if the time from time T1 to time T2 is short, there is a possibility that the ignition will be turned on or the vehicle will transition to the Ready state before the status detection operation is completed. In this regard, there is an advantage to performing the charge detection operation between time T3 and time T4. If the status detection operation is performed between time T3 and time T4, the vehicle power supply system 1 may omit the status detection operation the next time the vehicle V is started. For example, the vehicle power supply system 1 may perform control such that the status detection operation can be omitted for a predetermined time after the status detection operation is performed, by having the ECU 50 count a timer. In this case, the vehicle power supply system 1 may retain the estimated or determined result of the degradation state of the backup low-voltage power supply 23 obtained by the status detection operation until the next time the vehicle V is started.

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 comprising a first power supply system having a first low-voltage power supply and a first power load, a second power supply system having a second low-voltage power supply and a second power load and connected to the first power supply system, and a high-voltage power supply unit capable of outputting a voltage higher than a rated voltage of the first power supply system or the second power supply system, the second power supply system having a switching device capable of switching between a state in which the second low-voltage power supply is connected to the first power supply system so as to be able to supply power from the second low-voltage power supply to the first power supply system, and a state in which the second low-voltage power supply is disconnected from the first power supply system, and a vehicle power supply control device that controls the switching device, the vehicle power supply control device measuring an internal resistance of the second low-voltage power supply and and outputting a signal indicating whether the second low-voltage power supply is in a deteriorated state based on an estimation result of the estimation process, wherein the estimation process is capable of executing a first estimation process that performs estimation by measuring an internal resistance of the second low-voltage power supply when the second low-voltage power supply is being charged, and a second estimation process that performs estimation based on discharge power from the second low-voltage power supply, and wherein the second estimation process is executed when the high-voltage power supply unit of the vehicle power supply system is in an on state, power is being supplied from the high-voltage power supply unit to the first power supply system, and the state of the vehicle satisfies a predetermined condition.
According to configuration 1, in a configuration in which a second low-voltage power supply supplies power to a second power load and a switching device connects the second power supply system and the first power supply system so that power can be supplied from the second low-voltage power supply to a first power load, the degradation state of the second low-voltage power supply can be estimated with high accuracy. This allows the degradation state of the second low-voltage power supply to be estimated using a method that is less affected by the state of the vehicle, ensuring more opportunities to check the state of the second low-voltage power supply. For example, it is possible to avoid a situation in which the first power load or the second power load cannot be operated because the state of the second low-voltage power supply cannot be checked.

(Configuration 2) The vehicle power supply system according to configuration 1, wherein the predetermined condition includes a condition that the temperature of the second low-voltage power supply is equal to or lower than a first temperature.
According to configuration 2, even when it is difficult to estimate using the internal resistance when charging the second low-voltage power supply due to the low temperature of the second low-voltage power supply, the deterioration state of the second low-voltage power supply can be estimated with high accuracy.

(Configuration 3) The vehicle power supply system according to configuration 1 or 2, wherein the predetermined condition includes a condition in which the temperature of the second low-voltage power supply is equal to or higher than a second temperature.
According to configuration 3, even if it is not appropriate to charge the second low-voltage power supply due to the high temperature of the second low-voltage power supply, the degradation state of the second low-voltage power supply can be estimated with high accuracy.

(Configuration 4) The vehicle power supply system according to any one of Configurations 1 to 3, wherein the first low-voltage power supply and the second low-voltage power supply are constituted by chargeable and dischargeable batteries, and the predetermined condition includes a remaining capacity of the battery of the first low-voltage power supply being smaller than a remaining capacity of the battery of the second low-voltage power supply.
According to configuration 4, even when it is difficult to estimate using the internal resistance when charging the second low-voltage power supply due to the fact that the first low-voltage power supply is charged, the deterioration state of the second low-voltage power supply can be estimated with high accuracy.

(Configuration 5) A vehicle power supply system according to any one of configurations 1 to 4, wherein when the vehicle power supply control device executes the second estimation process, the vehicle power supply control device estimates whether the second low-voltage power supply is in a degraded state by measuring the internal resistance of the second low-voltage power supply based on the discharge power discharged by the second low-voltage power supply while the switching device is shut off.
According to configuration 5, the second low-voltage power supply is disconnected from the first power supply system, and the degradation state of the second low-voltage power supply can be estimated with high accuracy based on the discharge power of the second low-voltage power supply. This makes it possible to estimate the degradation state of the second low-voltage power supply with high accuracy using a method that is less susceptible to the influence of power consumption by other circuits in the vehicle power supply system.

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 (4)

a first power supply system having a first low-voltage power supply and a first power load;
a second power supply system including a second low-voltage power supply and a second power load, the second power supply system being connected to the first power supply system;
a high-voltage power supply unit capable of outputting a voltage higher than a rated voltage of the first power supply system or the second power supply system, the high-voltage power supply unit being mounted on a vehicle,
The second power supply system is
a switching device capable of switching between a state in which the second low-voltage power supply is connected to the first power supply system so that power can be supplied from the second low-voltage power supply to the first power supply system, and a state in which the second low-voltage power supply and the first power supply system are disconnected;
a vehicle power supply control device that controls the switching device,
The vehicle power supply control device includes:
an estimation process is performed to measure an internal resistance of the second low-voltage power supply and estimate whether or not the second low-voltage power supply is in a degraded state, and a signal indicating whether or not the second low-voltage power supply is in a degraded state is output based on an estimation result of the estimation process;
As the estimation process, a first estimation process can be executed in which estimation is performed by measuring an internal resistance of the second low-voltage power supply when charging the second low-voltage power supply, and a second estimation process can be executed in which estimation is performed based on discharge power from the second low-voltage power supply,
executes the second estimation process when the high-voltage power supply unit of the vehicle power supply system is in an on state, power is being supplied from the high-voltage power supply unit to the first power supply system, and a state of the vehicle satisfies a predetermined condition;
The predetermined condition includes the temperature of the second low-voltage power supply being equal to or lower than a first temperature threshold value that indicates an extremely low temperature that is unsuitable for measuring an internal resistance value through charging . a first power supply system having a first low-voltage power supply and a first power load;
a second power supply system including a second low-voltage power supply and a second power load, the second power supply system being connected to the first power supply system;
a high-voltage power supply unit capable of outputting a voltage higher than a rated voltage of the first power supply system or the second power supply system, the high-voltage power supply unit being mounted on a vehicle,
The second power supply system is
a switching device capable of switching between a state in which the second low-voltage power supply is connected to the first power supply system so that power can be supplied from the second low-voltage power supply to the first power supply system, and a state in which the second low-voltage power supply and the first power supply system are disconnected;
a vehicle power supply control device that controls the switching device,
The vehicle power supply control device includes:
an estimation process is performed to measure an internal resistance of the second low-voltage power supply and estimate whether or not the second low-voltage power supply is in a degraded state, and a signal indicating whether or not the second low-voltage power supply is in a degraded state is output based on an estimation result of the estimation process;
As the estimation process, a first estimation process can be executed in which estimation is performed by measuring an internal resistance of the second low-voltage power supply when charging the second low-voltage power supply, and a second estimation process can be executed in which estimation is performed based on discharge power from the second low-voltage power supply,
executes the second estimation process when the high-voltage power supply unit of the vehicle power supply system is in an on state, power is being supplied from the high-voltage power supply unit to the first power supply system, and a state of the vehicle satisfies a predetermined condition;
The predetermined condition includes the temperature of the second low-voltage power supply being equal to or higher than a second temperature threshold value that indicates a temperature too high for charging . a first power supply system having a first low-voltage power supply and a first power load;
a second power supply system including a second low-voltage power supply and a second power load, the second power supply system being connected to the first power supply system;
a high-voltage power supply unit capable of outputting a voltage higher than a rated voltage of the first power supply system or the second power supply system, the high-voltage power supply unit being mounted on a vehicle,
The second power supply system is
a switching device capable of switching between a state in which the second low-voltage power supply is connected to the first power supply system so that power can be supplied from the second low-voltage power supply to the first power supply system, and a state in which the second low-voltage power supply and the first power supply system are disconnected;
a vehicle power supply control device that controls the switching device,
The vehicle power supply control device includes:
an estimation process is performed to measure an internal resistance of the second low-voltage power supply and estimate whether or not the second low-voltage power supply is in a degraded state, and a signal indicating whether or not the second low-voltage power supply is in a degraded state is output based on an estimation result of the estimation process;
As the estimation process, a first estimation process can be executed in which estimation is performed by measuring an internal resistance of the second low-voltage power supply when charging the second low-voltage power supply, and a second estimation process can be executed in which estimation is performed based on discharge power from the second low-voltage power supply,
executes the second estimation process when the high-voltage power supply unit of the vehicle power supply system is in an on state, power is being supplied from the high-voltage power supply unit to the first power supply system, and a state of the vehicle satisfies a predetermined condition;
the first low-voltage power supply and the second low-voltage power supply are constituted by chargeable and dischargeable batteries,
The predetermined condition includes a condition in which the remaining capacity of the battery of the first low-voltage power supply is smaller than the remaining capacity of the battery of the second low-voltage power supply. 4. The vehicle power supply system according to claim 1, wherein, when the vehicle power supply control device executes the second estimation process, the vehicle power supply control device estimates whether the second low-voltage power supply is in a deteriorated state by measuring an internal resistance of the second low-voltage power supply based on discharge power discharged by the second low-voltage power supply with the switching device cut off.