JP7754355B2 - Method for controlling backup power storage device and vehicle power supply system - Google Patents

Description

This article relates to a method for controlling a backup power storage device and a vehicle power supply system.

Conventionally, vehicles have been known that include a main power storage device that supplies power to an electrical load mounted on the vehicle, and a backup power storage device that supplies power to the electrical load in the event of a power failure in which the main power storage device is unable to normally supply power to the electrical load (see, for example, Patent Document 1).

Specifically, the vehicle described in Patent Document 1 is an autonomous driving-compatible vehicle equipped with a main battery (equivalent to a main power storage device) and a sub-battery (equivalent to a backup power storage device). The vehicle control device described in the document extracts curves on the autonomous driving route based on map information, and charges the sub-battery before entering the curve based on the power consumed during curve driving from entering the extracted curve to exiting it and the amount of power stored in the sub-battery so that the amount of power stored in the sub-battery after curve driving is equal to or exceeds a predetermined threshold at which fail-operation is possible.

Japanese Patent Application Laid-Open No. 2020-21706

However, the vehicle control device described in Patent Document 1 above leaves room for improvement in terms of improving safety in the event of a power failure of the main battery.

This specification discloses technology that improves safety in the event of a power failure in the main power storage device.

A control method for a backup power storage device that backs up a main power storage device that supplies power to an electrical load mounted on a vehicle, the control method comprising: a determination step of determining whether the vehicle's driving conditions are such that preparations should be made for a power failure in which power is no longer normally supplied from the main power storage device to the electrical load; and a preparation step of preparing the backup power storage device so that it can start backup operations in a short period of time when the power failure occurs, if the determination step determines that the driving conditions are such that preparations should be made for a power failure.

This improves safety in the event of a power failure in the main power storage device.

FIG. 1 is a block diagram showing an electrical configuration of a vehicle according to a first embodiment; Schematic diagram of the power supply system A block diagram showing the electrical configuration of a backup power storage device. Backup preparation process flowchart Backup process flowchart Schematic diagram of a power supply system according to a third embodiment. FIG. 10 is a block diagram showing the electrical configuration of a backup power storage device according to a fourth embodiment.

(Outline of this embodiment)
(1) According to one aspect of the present invention, a control method for a backup power storage device that backs up a main power storage device that supplies power to an electrical load mounted on a vehicle includes a determination step of determining whether the driving conditions of the vehicle are such that preparations should be made for a power failure in which power is no longer normally supplied from the main power storage device to the electrical load, and a preparation step of preparing the backup power storage device so that it can start backup in a short time when the power failure occurs, if it is determined in the determination step that the driving conditions are such that preparations should be made for the power failure.

"Vehicle driving conditions" is not limited to current driving conditions, but may also be driving conditions in the near future. "Backing up the main power storage device" means supplying power to an electrical load in place of the main power storage device or in cooperation with the main power storage device. "Short period" means that the time from when a power failure occurs in the main power storage device to when backup begins is shorter than if the above-mentioned preparations are not made. "Power failure" can also be rephrased as "power supply failure."

If a power failure occurs in the main power storage device while the vehicle is running, it may become difficult to run the vehicle safely due to loss of control of the vehicle, etc. In the case of a vehicle equipped with a backup power storage device, even if a power failure occurs in the main power storage device, power is supplied to the electrical load from the backup power storage device, improving safety in the event of a power failure in the main power storage device.
However, since the vehicle continues to run between the time a power failure occurs in the main power storage device and the time backup begins, safety is reduced if backup cannot be started in a short time even if a backup power storage device is provided.

The inventors of the present application have discovered that a backup power storage device may need to be prepared before it can begin backup. Since it takes a certain amount of time to prepare for backup, if the backup is not prepared, it may not be possible to start backup in a short time if a power failure occurs in the main power storage device.

In the invention described in Patent Document 1, the sub-battery is charged before entering a curve. However, charging the sub-battery does not shorten the time between a power failure in the main battery and the start of backup. In other words, the invention described in Patent Document 1 does not prepare for the start of backup in a short period of time when a power failure in the main battery occurs. For this reason, there is room for improvement in terms of improving safety in the event of a power failure in the main battery.

According to the above control method, if it is determined that the vehicle's driving conditions require preparation for a power failure in which the main power storage device no longer supplies power to the electrical load normally (hereinafter simply referred to as a "power failure of the main power storage device"), the backup power storage device is prepared to begin backup in a short period of time in the event of a power failure of the main power storage device, so that backup can begin in a short period of time in the event of a power failure of the main power storage device. This improves safety in the event of a power failure of the main power storage device.

(2) According to one aspect of the present invention, the driving conditions for which the vehicle should be prepared for power failure may be at least one of the following: driving on a congested road, driving in an urban area, driving at night, driving in the rain, there are other vehicles around the vehicle, driving on a road with people on the sidewalk, and driving in autonomous mode.

When driving on a congested road, there is a higher possibility that other vehicles are around the vehicle than when driving on a road without congested traffic, and if a power failure occurs in the main power storage device and safe driving becomes difficult, there is a possibility of the vehicle colliding with another vehicle. Therefore, the risk is high if a power failure occurs in the main power storage device. For this reason, driving on a congested road can be said to be a driving situation that requires preparations to improve safety in the event of a power failure in the main power storage device (in other words, a driving situation in which preparations should be made for a power failure in the main power storage device).
When driving in urban areas, there is a higher likelihood of there being more vehicles on the roads and people crossing the roads than when driving in suburban areas, so if a power failure occurs in the main power storage device and safe driving becomes difficult, there is a possibility of contact with other vehicles or people. For this reason, the risk of a power failure in the main power storage device is high.

If a power failure occurs in the main power storage device while driving at night, the headlights will turn off. Since it is difficult to drive the vehicle safely when the headlights are off, the risk of a power failure in the main power storage device is higher than when driving during the day.
Visibility is poorer when driving in the rain than when driving on sunny days, so if a power failure occurs in the main power storage device and safe driving becomes difficult, the poor visibility makes it more difficult to avoid other vehicles or people, which increases the risk of a power failure in the main power storage device.

Even when there is no traffic jam, there may be other vehicles around the vehicle. In a situation where there are other vehicles around the vehicle, if a power failure occurs in the main power storage device and safe driving becomes difficult, there is a possibility of the vehicle colliding with another vehicle. For this reason, the risk of a power failure in the main power storage device is higher than when there are no other vehicles around the vehicle.
Even outside urban areas, there may be people on the sidewalk. When driving on a road with people on the sidewalk, there is a higher chance of people crossing the road than when driving on a road without people on the sidewalk. Therefore, if a power failure occurs in the main power storage device and safe driving becomes difficult, there is a possibility of contact with a person. Therefore, there is a high risk if a power failure occurs in the main power storage device.

In autonomous vehicles, if power supply to electrical loads is lost during autonomous driving, safe driving may become difficult. For this reason, in the case of vehicles that can switch between autonomous and manual driving, the risk of a power failure in the main power storage device is higher when driving in autonomous mode than when driving manually.

The above control method improves safety in the event of a power failure in the main power storage device, as the driving conditions that require preparation for a power failure in the main power storage device are at least one of the following: driving on congested roads, driving in urban areas, driving at night, driving in the rain, there are other vehicles around the vehicle, driving on roads with people on the sidewalk, and driving in autonomous mode.

While it is not necessarily true that there is a high probability that other vehicles or people are around the vehicle when driving at night, in the rain, or in autonomous driving mode, there is a high probability that other vehicles or people are around the vehicle when driving on congested roads, in urban areas, when there are other vehicles around the vehicle, or when driving on roads with people on the sidewalk. The invention described in Patent Document 1 above is intended to prevent fail-operation from becoming impossible after driving around a curve, but does not sufficiently consider improving the safety of third parties in the event of a power failure of the main battery.

In contrast, the above control method prepares for backup when the vehicle is traveling on a congested road, in an urban area, or on a road with other vehicles around the vehicle or people on the sidewalk, thereby improving the safety of not only the vehicle's occupants but also third parties around the vehicle. Therefore, safety is ensured from a more comprehensive perspective than the invention described in Patent Document 1.

(3) According to one aspect of the present invention, a control method for a backup power storage device that backs up a main power storage device that supplies power to an electrical load mounted on a vehicle may include a prediction step of predicting an abnormality in the main power storage device, and a preparation step of, in response to an abnormality predicted in the prediction step, preparing the backup power storage device so that it can start backup in a short period of time when a power failure occurs in which power is no longer normally supplied from the main power storage device to the electrical load.

The above preparation process includes not only the case where preparation is always made when an abnormality is predicted, but also the case where preparation is made when other conditions are met in addition to the abnormality being predicted. For this reason, there are cases where a backup is not prepared even if an abnormality is predicted.
According to the above control method, in response to prediction of an abnormality in the main power storage device, the backup power storage device is prepared to start backup in a short time in the event of a power failure in the main power storage device, so that backup can start in a short time in the event of a power failure in the main power storage device, thereby improving safety in the event of a power failure in the main power storage device.

(4) According to one aspect of the present invention, the backup power storage device comprises a power storage element, a first current interruption device connected in series to the power storage element, and a management device that operates using power supplied from the power storage element, the management device switching the first current interruption device to a cut-off state when the main power storage device is not being backed up, and switching the first current interruption device to a conducting state when the main power storage device is being backed up; the management device transitions to a power saving mode when the main power storage device is not being backed up, and the control method may transition the management device to a normal mode in the preparation step.

According to the above control method, when the main storage device is not being backed up, the first current interruption device is set to an interrupted state, thereby preventing the charge state of the backup storage device from decreasing due to the minute dark current flowing from the backup storage device to the electrical load.
According to the control method described above, when the main power storage device is not backed up, the management device switches to a power saving mode. Because the management device operates using power supplied from the power storage elements, switching to the power saving mode also reduces the power consumption of the power storage elements by the management device.

However, in power saving mode, it takes longer for the management device to power the first current interruption device than in normal mode, so backup cannot be started in a short time when a power failure occurs in the main power storage device.
According to the above control method, when it is determined that the driving situation requires preparation for a power failure of the main power storage device, the management device is switched to the normal mode, so that the first current interruption device can be switched to the conducting state in a short time when a power failure of the main power storage device occurs. Therefore, backup can be started in a short time when a power failure of the main power storage device occurs.

(5) According to one aspect of the present invention, the backup power storage device includes a power storage element and a first current interruption device connected in series to the power storage element, and the control method includes a step of switching the first current interruption device to an interrupted state when the main power storage device is not being backed up, and the first current interruption device may be switched to an energized state during the preparation step.

According to the above control method, when the main storage device is not being backed up, the first current interruption device is set to an interrupted state, thereby preventing the charge state of the backup storage device from decreasing due to the minute dark current flowing from the backup storage device to the electrical load.
It takes a certain amount of time to switch the first current interruption device from an interrupted state to an energized state. For example, if a contact switch such as a relay is used as the first current interruption device, it takes a long time, from several tens of milliseconds to several hundreds of milliseconds, to switch from an interrupted state to an energized state. Even if the first current interruption device is a semiconductor switch such as a field effect transistor (FET), a certain amount of time is required. For this reason, if the first current interruption device is switched to an energized state after a power failure occurs in the main power storage device, backup cannot be started in a short time.
According to the above control method, if it is determined that the driving conditions require preparation for a power failure of the main power storage device, the first current interruption device is energized, so backup can be started in a shorter time than if the first current interruption device is energized after a power failure of the main power storage device occurs.

(6) According to one aspect of the present invention, a second current interruption device is provided between the electrical load and the backup power storage device, and the control method may include a step of energizing the second current interruption device when the power failure occurs.

According to the above control method, when a power failure occurs, the second current interruption device is energized, allowing the backup storage device to back up the main storage device.

(7) According to one aspect of the present invention, in the preparation step, a storage element included in the backup storage device may be heated.

The temperature of the storage element of a backup energy storage device may drop while the device is in standby mode. A low temperature in the storage element reduces the output voltage. When backup begins, the temperature of the storage element rises due to the flow of current, which in turn increases the output voltage. However, it takes time for the output voltage to rise to the rated voltage, and it may not be possible to start backup at the rated voltage in a short time.
According to the above control method, when it is determined that the driving conditions require preparation for a power failure of the main power storage device, the storage element is heated, so that backup at the rated voltage can be started in a short time when a power failure of the main power storage device occurs.

(8) According to one aspect of the present invention, the method may include a step of slowing the communication speed between a control device provided in the vehicle and a management device provided in the backup power storage device below a reference speed when the backup power storage device does not back up the main power storage device, and the preparation step may return the communication speed between the control device and the management device to the reference speed.

If the communication speed between the control device equipped in the vehicle and the management device equipped in the backup power storage device is slow, when the vehicle's control device detects a power failure in the main power storage device and instructs the backup power storage device to back up, it takes time for the management device for the backup power storage device to receive the instruction.
According to the above control method, when it is determined that the driving situation requires preparation for a power failure of the main power storage device, the communication speed between the control device provided in the vehicle and the management device provided in the backup power storage device is returned to the reference speed, thereby shortening the time until the management device for the backup power storage device receives a backup instruction when a power failure of the main power storage device occurs. As a result, backup can be started in a short time when a power failure of the main power storage device occurs.

(9) According to one aspect of the present invention, the method may include a step of charging the backup power storage device when the determination step determines that the driving situation is such that preparation for a power failure is necessary.

If the state of charge (SOC) of the backup power storage device is low, there is a possibility that it will not be able to supply sufficient power to the electrical load when backup is required.
According to the above control method, if it is determined that the driving conditions require preparation for a power failure of the main power storage device, the backup power storage device is charged in advance, thereby increasing the possibility that sufficient power can be supplied to the electrical load when backup is required.

(10) According to one aspect of the present invention, the method may include a step of canceling the preparation state of the backup power storage device if, after preparation in the preparation step, the driving conditions of the vehicle are no longer conditions that require preparation for the power failure.

Maintaining a backup ready state (prepared state) may require the consumption of power from the backup storage device or the main storage device. According to the control method described above, the prepared state is canceled when the driving conditions no longer require preparation for a power failure of the main storage device, thereby reducing power consumption from the backup storage device or the main storage device.

(11) According to one aspect of the present invention, the method may include a step of discharging the backup power storage device to reduce its state of charge if, after preparation in the preparation step, the vehicle's driving conditions are no longer conditions that require preparation for the power failure.

Storage devices are prone to deterioration if they are maintained at a high state of charge. According to the above control method, when the driving conditions are no longer such that preparation for a power failure of the main storage device is necessary, the state of charge of the backup storage device is reduced, thereby suppressing deterioration of the backup storage device.

(12) According to one aspect of the present invention, the method may include a step of charging the backup power storage device in response to an abnormality being predicted in the prediction step.

The above control method charges the backup storage device in advance when an abnormality in the main storage device is predicted, increasing the likelihood that sufficient power will be able to be supplied to the electrical load when backup is needed.

(13) According to one aspect of the present invention, the method may include a step of canceling the preparation state of the backup power storage device if, after preparation in the preparation step, an abnormality in the main power storage device is no longer predicted.

The above control method cancels the standby state when an abnormality in the main power storage device is no longer predicted, thereby reducing power consumption in the backup power storage device or the main power storage device.

(14) According to one aspect of the present invention, the method may include a step of discharging the backup power storage device to reduce its state of charge if, after preparation in the preparation step, an abnormality in the main power storage device is no longer predicted.

The above control method reduces the state of charge of the backup storage device when an abnormality in the main storage device is no longer predicted, thereby suppressing deterioration of the backup storage device.

The invention disclosed in this specification can be realized in various forms, such as an apparatus, a method, a computer program for implementing the functions of these apparatus or methods, and a recording medium on which the computer program is recorded.

<Embodiment 1>
The first embodiment will be described with reference to Figures 1 to 5. In the following description, the reference numerals of the drawings may be omitted for the same components, with some exceptions.

(1) Electrical Configuration of Vehicle The electrical configuration of a vehicle 1 according to the first embodiment will be described with reference to Fig. 1 . The vehicle 1 is an electric vehicle and an autonomous vehicle. The vehicle 1 includes a vehicle ECU (Electronic Control Unit) 11, a memory unit 12, various sensors 13, an autonomous driving control unit 14, an electric motor 25 that drives the vehicle 1, auxiliary machinery 26 (an example of an electrical load), a wireless communication unit 16, and a power supply system 17. The vehicle ECU 11 is an example of a control device included in the vehicle 1.

The vehicle ECU 11 is a computer that controls each part of the vehicle 1. The vehicle ECU 11 is equipped with a CPU 11A, a ROM 11B, a RAM 11C, and a first communication unit 11D. The ROM 11B stores various control programs executed by the CPU 11A. The first communication unit 11D is a communication circuit that allows the vehicle ECU 11 to communicate with each part of the vehicle 1.

The storage unit 12 stores various data such as map data.
The various sensors 13 are used for automatic driving and for detecting the driving conditions of the vehicle 1, which will be described later. The various sensors 13 include a GPS receiver, a gyro sensor, a vehicle speed sensor, an acceleration sensor, a front detection device, a rear detection device, a left side detection device, a right side detection device, a human presence sensor, etc.
The GPS receiver is a sensor that detects the vehicle's position based on a signal transmitted from a Global Positioning System (GPS), which is one type of satellite positioning system. The GPS receiver may detect the vehicle's position based on a signal transmitted from a satellite positioning system other than GPS. The gyro sensor is a sensor that detects the angular velocity of the vehicle 1. The vehicle speed sensor is a sensor that detects the speed of the vehicle 1. The acceleration sensor is a sensor that detects the acceleration of the vehicle 1.

The front detection device, rear detection device, left side detection device, and right side detection device are sensors that detect objects and road facilities (lanes, intersections, traffic lights, etc.) that exist in front of, behind, to the left, and to the right of the vehicle. Cameras, laser radars, millimeter-wave radars, etc. can be used as these detection devices.
The human presence sensor is a device that detects people around the vehicle. For example, an infrared sensor can be used as the human presence sensor. People around the vehicle may be detected by a front detection device, a rear detection device, a left side detection device, and a right side detection device.

The autonomous driving control unit 14 is a computer that controls autonomous driving of the vehicle 1 based on map data stored in the memory unit 12, information detected by the various sensors 13, information acquired by the wireless communication unit 16, etc. The autonomous driving control unit 14 includes a CPU, ROM, RAM, etc. The ROM stores a control program and various data for the CPU to control autonomous driving.
The auxiliary devices 26 are devices that operate on electricity, and include electric power steering, electric brakes, headlights, wipers, air conditioners, and the like.

The wireless communication unit 16 is a circuit for receiving traffic information around the vehicle (such as traffic congestion information, accident/broken-down vehicle/construction information, speed limit/lane restriction information, etc.) from the Intelligent Transport System (ITS). The Intelligent Transport System is a system that transmits road traffic information collected, processed, and edited by the Road Traffic Information and Communication System Center, a general incorporated foundation, to the vehicle 1 via information transmission devices (beacons) installed on the road or via FM multiplex broadcasting.

The wireless communication unit 16 may communicate with a server on the Internet via a wireless access network such as LTE (Long Term Evolution) and receive traffic congestion information, weather information around the vehicle, and the like from the server.
The wireless communication unit 16 may perform vehicle-to-vehicle communication with other vehicles. Vehicle-to-vehicle communication is communication in which vehicles wirelessly transmit and receive information about their own vehicles, such as their positions and speeds, to prevent head-on collisions, right-turn accidents, left-turn accidents, and the like at intersections with poor visibility.

The power supply system 17 will be described with reference to Figure 2. The power supply system 17 includes a drive power storage device 21 that supplies power to the electric motor 25, an auxiliary power storage device 22 (an example of a main power storage device) that supplies power to auxiliary equipment 26, a backup power storage device 23 that backs up the auxiliary power storage device 22, and a DC/DC converter 24. The vehicle ECU 11, the auxiliary power storage device 22, and the backup power storage device 23 are an example of a power supply system according to embodiment 1.

The backup power storage device 23 is a redundant system for the auxiliary power storage device 22, and is connected to the auxiliary devices 26 and DC/DC converter 24 by a power line separate from that of the auxiliary power storage device 22. The backup power storage device 23 does not need to supply power to all of the auxiliary devices 26, but may supply power only to the minimum number of auxiliary devices 26 necessary for safe driving.

The drive storage device 21 is a high-voltage storage device rated at, for example, 100V. The auxiliary storage device 22 and the backup storage device 23 are rated at, for example, 12V. When the auxiliary storage device 22 or the backup storage device 23 is charged while the vehicle 1 is traveling, it is charged by the drive storage device 21. When these storage devices are charged by the drive storage device 21, the voltage is converted by the DC/DC converter 24.

Power failure may occur in the auxiliary storage device 22 due to various causes. For example, if the auxiliary storage device 22 becomes excessively charged (overcharged) due to a malfunction of the DC/DC converter 24, or if the auxiliary storage device 22 becomes excessively discharged (overdischarged) due to a malfunction of the DC/DC converter 24, the first current interruption device 39 (see FIG. 3), described below, may enter an interrupted state (open state, off state, open state), resulting in a power failure. Alternatively, power failure may occur if the first current interruption device 3, described below, remains in an interrupted state due to a malfunction. Alternatively, power failure may occur due to deterioration of the auxiliary storage device 22. Alternatively, power failure may occur due to a break in the power line supplying power from the auxiliary storage device 22 to the auxiliary devices 26.

(2) Electrical Configuration of the Auxiliary Electric Storage Device and the Backup Electric Storage Device The electrical configuration of the auxiliary electric storage device 22 is substantially the same as the electrical configuration of the backup electric storage device 23. Here, the backup electric storage device 23 will be described as an example.
As shown in FIG. 3 , the backup power storage device 23 includes a battery pack 30 including a plurality of battery cells 30A (an example of a power storage element), a BMU 31 (Battery Management Unit), and a communication connector 32. The BMU 31 is an example of a management device included in the backup power storage device 23. The vehicle ECU 11 and the BMU 31 together form a control unit of the power supply system.

The positive electrode side of the battery pack 30 is connected to the positive electrode external terminal 34P via power line 33P, and the negative electrode side is connected to the negative electrode external terminal 34N via power line 33N. The battery pack 30 has 12 battery cells 30A connected in three parallel connections and four in series. In Figure 3, three battery cells 30A connected in parallel are represented by a single battery symbol. The battery cells 30A are secondary batteries that can be repeatedly charged and discharged, and specifically, are lithium-ion secondary batteries, for example.

The BMU 31 includes a current sensor 35, a voltage detection circuit 36, a temperature sensor 37, a first current interruption device 39, and a management unit 38. The current sensor 35 is provided on the power line 33N, and measures the charge/discharge current of the battery pack 30 and outputs the measured current to the management unit 38.
The voltage detection circuit 36 is connected to both ends of each battery cell 30A by a signal line. The voltage detection circuit 36 measures the battery voltage of each battery cell 30A and outputs the measured voltage to the management unit 38. The total voltage of the battery pack 30 is the sum of the voltages of the four battery cells 30A connected in series.
The temperature sensor 37 measures the temperature of the battery cell 30A and outputs the temperature to the management unit 38. Two or more temperature sensors 37 are provided. Each temperature sensor 37 measures the temperature of a different battery cell 30A. However, only one temperature sensor 37 may be provided.

The first current interruption device 39 is provided on the power line 33P. A contact switch (mechanical type) such as a relay, or a semiconductor switch such as a field effect transistor (FET) can be used as the first current interruption device 39. The first current interruption device 39 is switched between a conducting state (closed state, on state, closed state) and a blocking state (open state, off state, open state) by the management unit 38.
The management unit 38 includes a microcomputer 38A in which a CPU, RAM, etc. are integrated into one chip, a storage unit 38B, and a second communication unit 38C. The management unit 38 operates using power supplied from the battery cell 30A. Various programs, data, etc. are stored in the storage unit 38B. The microcomputer 38A executes the programs stored in the storage unit 38B to perform various management processes such as SOC estimation processing and protection processing, which will be described later. The second communication unit 38C is a circuit that allows the management unit 38 to communicate with the vehicle ECU 11.

The communication connector 32 is a connector to which a communication cable is connected so that the management unit 38 can communicate with the vehicle ECU 11.

The SOC estimation process and protection process executed by the management unit 38 will be described below. The SOC estimation process is a process for estimating the SOC of the backup power storage device 23. Methods for estimating the SOC include measuring the current value at predetermined time intervals (e.g., 10 milliseconds) using the current sensor 35 and adding or subtracting the measured current value from an initial value (current integration method), and estimating the SOC from the open circuit voltage (OCV) of the backup power storage device 23.

The protection process is a process for protecting the backup power storage device 23 from abnormalities. The management unit 38 determines that the backup power storage device 23 is abnormal if, for example, the estimated SOC is above a predetermined upper limit (overcharging), the SOC is below a predetermined lower limit (overdischarging), the current value measured by the current sensor 35 is above a predetermined value (overcurrent), or the temperature measured by the temperature sensor 37 is above a predetermined value. If the management unit 38 determines that the backup power storage device 23 is abnormal, it protects the backup power storage device 23 from abnormalities by switching the first current interruption device 39 to an interrupted state. The abnormalities described above are examples, and abnormalities in the backup power storage device 23 are not limited to these.

(3) Backup by Backup Power Storage Device The backup power storage device 23 will be described with reference to Fig. 3. When the backup power storage device 22 for the auxiliary machinery is not being backed up, the management unit 38 of the backup power storage device 23 sets the first current interruption device 39 to an interruption state in order to prevent the power of the backup power storage device 23 from being consumed by dark current flowing from the backup power storage device 23 to the auxiliary machinery 26.

As mentioned above, the management unit 38 operates using power supplied from the battery cell 30A. Therefore, even when the auxiliary power storage device 22 is not being backed up, if the management unit 38 is active, power will be consumed by the management unit 38. For this reason, in order to reduce power consumption, the management unit 38 switches the first current interruption device 39 to an interrupted state and then transitions to sleep mode (an example of a power saving mode). In sleep mode, the power supply to functions other than those waiting for an external activation signal is cut off. This reduces power consumption by the management unit 38.

The vehicle ECU 11 will be described with reference to Figure 1. The vehicle ECU 11 monitors the auxiliary power storage device 22, and in the event of a power failure in the auxiliary power storage device 22, sends a start-up signal to the management unit 38 of the backup power storage device 23 via the first communication unit 11D. As will be described in more detail below, the vehicle ECU 11 may also send a start-up signal to the management unit 38 of the backup power storage device 23 even if a power failure has not occurred in the auxiliary power storage device 22.

A power failure of the auxiliary storage device 22 can be detected by any appropriate method. For example, the vehicle ECU 11 may determine that a power failure of the auxiliary storage device 22 has occurred if the current value of the current flowing from the auxiliary storage device 22 to the auxiliary equipment 26 is equal to or less than a predetermined value, or may determine that a power failure of the auxiliary storage device 22 has occurred if the voltage of the auxiliary storage device 22 has dropped to or below a predetermined value. Alternatively, the management unit 38 of the auxiliary storage device 22 may notify the vehicle ECU 11 that the first current interruption device 39 has been switched to the switched state when the management unit 38 has switched the first current interruption device 39 to the switched state as a result of protection processing. The vehicle ECU 11 may determine that a power failure of the auxiliary storage device 22 has occurred when the vehicle ECU 11 is notified by the auxiliary storage device 22 that the first current interruption device 39 has been switched to the switched state.

The management unit 38 of the backup power storage device 23 starts up (transitions from sleep mode to normal mode) when it receives a start-up signal from the vehicle ECU 11. After the management unit 38 of the backup power storage device 23 starts up, the vehicle ECU 11 instructs the management unit 38 of the backup power storage device 23 to perform a backup. When the management unit 38 of the backup power storage device 23 receives the backup instruction, it switches the first current interruption device 39 of the backup power storage device 23 to a conducting state. This starts the backup.

However, since it takes a certain amount of time to start the management unit 38 of the backup power storage device 23, if the management unit 38 is started after a power failure occurs in the auxiliary power storage device 22, it will take some time for backup to begin. For this reason, the vehicle ECU 11 repeatedly performs a determination process at predetermined time intervals, such as every 5 seconds, while the vehicle 1 is traveling to determine whether the current driving conditions of the vehicle 1 are such that preparation for a power failure in the auxiliary power storage device 22 is necessary. The determination process will be described later. The determination process may be performed not only while the vehicle is traveling, but also while the vehicle is stopped.

When the vehicle ECU 11 determines that the driving situation requires preparation for a power failure of the auxiliary power storage device 22, the vehicle ECU 11 transmits a start signal to the management unit 38 even if a power failure of the auxiliary power storage device 22 has not occurred. This starts the management unit 38 (an example of a preparation process or a preparation step). Starting the management unit 38 is an example of preparation.
If a power failure subsequently occurs in the auxiliary power storage device 22, the management unit 38 of the backup power storage device 23 has already been activated, and therefore the vehicle ECU 11 instructs the management unit 38 of the backup power storage device 23 to perform backup. Therefore, backup can be started in a short time when a power failure occurs in the auxiliary power storage device 22, compared to when the management unit 38 is activated after a power failure occurs in the auxiliary power storage device 22.

(3-1) Judgment process The vehicle ECU 11 judges whether the current driving condition of the vehicle 1 corresponds to at least one of the following (a) to (g), and if so, judges that the driving condition is one in which preparation for a power failure of the auxiliary storage device 22 is required.

(a) Situation when driving on a congested road (b) Situation when driving in an urban area (c) Situation when driving at night (d) Situation when driving in the rain (e) Situation when there are other vehicles around vehicle 1 (f) Situation when driving on a road with people on the sidewalk (g) Situation when driving in autonomous driving mode

The determination of whether the vehicle's driving conditions correspond to the above-mentioned driving conditions will be described below.
(a) Situation of traveling on a congested road The vehicle ECU 11 detects the vehicle's position using the GPS receiver and receives congestion information from an intelligent road traffic system, a server on the Internet, etc. using the wireless communication unit 16. If the detected vehicle position is included in a congested section indicated by the received congestion information, the vehicle ECU 11 determines that the vehicle is traveling on a congested road.

The vehicle ECU 11 determines whether there are other vehicles around the vehicle using the front detection device, rear detection device, left side detection device, right side detection device, and vehicle-to-vehicle communication via the wireless communication unit 16, and also detects the vehicle speed of the vehicle using a vehicle speed sensor, and if there are other vehicles around the vehicle and the vehicle speed of the vehicle is below a predetermined speed, it may determine that the vehicle is traveling on a congested road.
The method for determining whether or not the vehicle is traveling on a congested road is not limited to these, and any other appropriate method can be used.

(b) Driving in an urban area The vehicle ECU 11 detects the vehicle's position from the signal received by the GPS receiver and determines from map data whether the detected vehicle position is in an urban area or a suburban area. If the vehicle position is in an urban area, the vehicle ECU 11 determines that the vehicle is driving in an urban area. The method for determining whether the vehicle is driving in an urban area is not limited to this, and any appropriate method can be used.

(c) Nighttime Driving Situation When the headlights of the vehicle 1 are turned on/off, a corresponding signal is sent to the vehicle ECU 11. The vehicle ECU 11 determines that the vehicle is driving at night when the headlights are on. A nighttime period (start time and end time of nighttime) may be set in advance. The vehicle ECU 11 may determine that the vehicle is driving at night when the current time is included in the nighttime period. The method of determining whether the vehicle is driving at night is not limited to these, and any appropriate method may be used.

(d) Rainy Weather Driving Situation When the wipers of the vehicle 1 are turned on/off, a corresponding signal is transmitted to the vehicle ECU 11. When the wipers are on, the vehicle ECU 11 determines that the vehicle is driving in the rain.
The vehicle ECU 11 may detect the vehicle's position using the GPS receiver and may also receive weather information from an intelligent road traffic system, a server on the Internet, or the like using the wireless communication unit 16. If the detected vehicle position is included in an area that is determined to be rainy in the received weather information, the vehicle ECU 11 may determine that the vehicle is traveling in rainy weather. The method for determining whether the vehicle is traveling in rainy weather is not limited to these, and any appropriate method may be used.

(e) Situation where there is another vehicle around the vehicle The vehicle ECU 11 detects other vehicles around the vehicle 1 (for example, within a radius of 30 meters from the vehicle 1) using the front detection device, rear detection device, left side detection device, and right side detection device. If the number of other vehicles detected is equal to or greater than a predetermined number (for example, one or more), the vehicle ECU 11 determines that there is another vehicle around the vehicle 1. The above-mentioned radius of 30 meters is one example. The radius within which the periphery of the vehicle 1 is defined can be determined as appropriate.
The vehicle ECU 11 may determine, through vehicle-to-vehicle communication, whether or not there is another vehicle around the vehicle 1. The method for determining whether or not there is another vehicle around the vehicle 1 is not limited to these, and any appropriate method may be used for the determination.

(f) Situation when the vehicle 1 is traveling on a road with people on the sidewalk Here, an example will be described in which the vehicle 1 is driving on the left side of the road. The vehicle ECU 11 detects people walking on the sidewalk to the left of the vehicle using a human presence sensor and determines the number of people per unit distance (e.g., per 100 m). If the number of people per unit distance is equal to or greater than a predetermined number (e.g., 10 or more people), the vehicle ECU 11 determines that the vehicle is traveling on a road with people on the sidewalk.
The vehicle ECU 11 may detect a person using the left side detection device, or may detect a person by combining a human presence sensor and the left side detection device. The method of determining whether or not the vehicle is traveling on a road with people on the sidewalk is not limited to these, and any appropriate method may be used.

(g) Automatic driving status Generally, an automatic driving vehicle can switch between automatic driving and manual driving by the driver of the vehicle 1. When the automatic driving status is switched to, the vehicle ECU 11 determines that the vehicle is in an automatic driving status.
Switching between automatic driving and manual driving can also be achieved by a method other than the driver. For example, the vehicle ECU 11 may detect the driver's complexion, facial expression, posture, body temperature, etc. using a camera or other sensor while the vehicle 1 is being driven manually. The vehicle ECU 11 may determine the driver's health condition, drowsiness, etc. from the detection results, and switch to automatic driving if it determines that the driver is in poor health or drowsy.

(3-2) Backup Control by Vehicle ECU The backup preparation process and backup process executed by the vehicle ECU 11 will be described.
The backup preparation process will be described with reference to Fig. 4. The backup preparation process is repeatedly executed at predetermined time intervals, such as every five seconds, while the vehicle 1 is running.
In step S<b>101 , the vehicle ECU 11 detects the driving conditions of the vehicle 1 .
In S102, the vehicle ECU 11 determines whether the detected driving situation is one in which preparation for a power failure of the auxiliary power storage device 22 is required (an example of a determination process or determination step). If the vehicle ECU 11 determines that the driving situation is one in which preparation for a power failure of the auxiliary power storage device 22 is required, the process proceeds to S103, and if the vehicle ECU 11 determines that the driving situation is not one in which preparation for a power failure is required, the process proceeds to S106.

In S103, the vehicle ECU 11 determines whether the backup power storage device 23 is in backup mode. If not, the process proceeds to S104, and if backup mode is in progress, the process ends.
In S104, the vehicle ECU 11 transmits a start signal to the backup power storage device 23 (an example of a preparation process). However, if the management unit 38 has already been activated and the backup is already prepared, the vehicle ECU 11 does not transmit the start signal. In the following description, the state in which the management unit 38 has been activated and the backup is already prepared is referred to as the "preparation state."
In S105, the vehicle ECU 11 controls the DC/DC converter 24 to charge the backup power storage device 23 (an example of a step of charging a backup power storage device).

In S106, the vehicle ECU 11 determines whether the backup power storage device 23 is in a ready state. If it is in a ready state, the process proceeds to S107, and if it is not in a ready state, the process ends.
In S107, the vehicle ECU 11 determines whether the backup power storage device 23 is in backup mode. If not, the process proceeds to S108, and if backup mode is in progress, the process ends.
In S108, the vehicle ECU 11 instructs the backup power storage device 23 to cancel the preparation state. When the instruction to cancel is received, the management unit 38 of the backup power storage device 23 switches the first current interruption device 39 to the interruption state and then transitions to sleep mode (an example of a process for canceling the preparation state). This cancels the preparation state.

The backup process will be described with reference to Fig. 5. The backup process is repeatedly executed at predetermined time intervals, such as every five seconds, while the vehicle 1 is running.
In S201, the vehicle ECU 11 determines whether a power failure has occurred in the auxiliary power storage device 22. If a power failure has occurred, the process proceeds to S202, and if not, the process ends.
In S202, the vehicle ECU 11 determines whether the backup power storage device 23 is in a ready state, and if it is in a ready state, the process proceeds to S203, and if it is not in a ready state, the process proceeds to S204.

In S203, the vehicle ECU 11 instructs the backup power storage device 23 to perform backup.
In S204, the vehicle ECU 11 transmits a start signal to the backup power storage device 23.
In S205, after the management unit 38 of the backup power storage device 23 is started, the vehicle ECU 11 instructs the backup power storage device 23 to perform backup.

(4) Effects of the Embodiment According to the control method for backup power storage device 23 according to the first embodiment, when it is determined that the driving situation requires preparation for a power failure of auxiliary power storage device 22, backup power storage device 23 is prepared so as to start backup in a short time when a power failure occurs in auxiliary power storage device 22, so that backup can be started in a short time when a power failure occurs in auxiliary power storage device 22. This improves safety in the event of a power failure in auxiliary power storage device 22.

According to the above control method, the driving conditions that require preparation for power failure are at least one of the above-mentioned (a) to (g), thereby improving safety in the event of a power failure of the auxiliary storage device 22.
When the vehicle 1 is traveling on a congested road, in an urban area, with other vehicles around the vehicle 1, or on a road with people on the sidewalk, there is a high possibility that other vehicles or people are around the vehicle 1. In the above control method, when the vehicle 1 is traveling in any of these situations, preparations are made to start backup in a short time in the event of a power failure of the auxiliary power storage device 22, thereby improving the safety of not only the occupants of the vehicle 1 but also third parties around the vehicle 1. Therefore, safety is ensured from a more comprehensive perspective than in the invention described in Patent Document 1.

According to the above control method, if it is determined that the driving situation requires preparation for a power failure of the auxiliary storage device 22, the management unit 38 of the backup storage device 23 is activated, so that the first current interruption device 39 can be switched to an energized state in a short time when a power failure occurs in the auxiliary storage device 22. Therefore, backup can be started in a short time when a power failure occurs in the auxiliary storage device 22.

According to the above control method, if it is determined that the driving conditions require preparation for a power failure of the auxiliary storage device 22, the backup storage device 23 is charged in advance, thereby increasing the likelihood that sufficient power can be supplied to the auxiliary devices 26 when backup is required.

According to the above control method, when the driving conditions no longer require preparation for a power failure of the auxiliary storage device 22, the preparation state is canceled (S108), thereby reducing power consumption of the backup storage device 23.

<Embodiment 2>
The configuration of the vehicle 1 according to the second embodiment is substantially the same as that of the first embodiment.
The management unit 38 of the auxiliary power storage device 22 according to the second embodiment predicts an abnormality in the auxiliary power storage device 22 based on the SOC estimated by the SOC estimation process described above, the voltage measured by the voltage detection circuit 36, the temperature measured by the temperature sensor 37, and the like (an example of a prediction process). For example, an SOC of 95% or higher is assumed to indicate an abnormality (overcharging). In this case, the management unit 38 determines that an abnormality is predicted when the SOC changes, for example, from less than 90% to 90% or higher. The same applies to abnormalities such as overdischarge, voltage, and temperature.
When an abnormality in the auxiliary power storage device 22 is predicted, the management unit 38 of the auxiliary power storage device 22 notifies the vehicle ECU 11 that an abnormality in the auxiliary power storage device 22 is predicted.

If an abnormality occurs in the auxiliary storage device 22, the first current interruption device 39 will be shut off. Therefore, if an abnormality in the auxiliary storage device 22 is predicted, there is a possibility that a power failure of the auxiliary storage device 22 will occur in the near future. For this reason, when the vehicle ECU 11 is notified that an abnormality in the auxiliary storage device 22 is predicted, it prepares the backup storage device 23 so that it can start backup in a short period of time if a power failure occurs in the auxiliary storage device 22. This preparation is the same as in embodiment 1, so a description thereof will be omitted.

As in the first embodiment, when the vehicle ECU 11 is notified that an abnormality in the auxiliary power storage device 22 is predicted, the vehicle ECU 11 charges the backup power storage device 23 .
When an abnormality is no longer predicted, the auxiliary power storage device 22 notifies the vehicle ECU 11 that an abnormality is no longer predicted. When the vehicle ECU 11 is notified that an abnormality in the auxiliary power storage device 22 is no longer predicted, the vehicle ECU 11 cancels the standby state of the backup power storage device 23 and further discharges the backup power storage device 23 to reduce the SOC.

According to the control method of embodiment 2, if an abnormality in the auxiliary storage device 22 is predicted, the backup storage device 23 is prepared to start backup in a short time when a power failure occurs in the auxiliary storage device 22. Therefore, backup can be started in a short time when a power failure occurs in the auxiliary storage device 22, compared to when backup preparations are made after a power failure occurs in the auxiliary storage device 22. This improves safety in the event of a power failure in the auxiliary storage device 22.

According to the control method of embodiment 2, the backup power storage device 23 is charged in advance in response to a predicted abnormality in the auxiliary power storage device 22, thereby increasing the likelihood that sufficient power can be supplied to the auxiliary devices 26 when backup is required.

According to the control method of embodiment 2, the standby state is canceled when an abnormality in the auxiliary storage device 22 is no longer predicted, thereby reducing power consumption in the backup storage device 23.

According to the control method of embodiment 2, when an abnormality in the auxiliary storage device 22 is no longer predicted, the SOC of the backup storage device 23 is reduced, thereby suppressing deterioration of the backup storage device 23.

<Embodiment 3>
The third embodiment will be described with reference to Fig. 6. The third embodiment is a modification of the first or second embodiment. Here, the third embodiment will be described as a modification of the first embodiment.
6, in the third embodiment, a second current interruption device 40 is provided between the backup power storage device 23 and the auxiliary machinery 26. The second current interruption device 40 is opened and closed by the vehicle ECU 11.

When the management unit 38 of the backup power storage device 23 according to the third embodiment is not backing up the auxiliary power storage device 22, it transitions to a low-frequency mode (an example of a power-saving mode) in which the operating clock is slower than in normal mode, rather than to a sleep mode. Because the operating clock is slow in low-frequency mode, when the vehicle ECU 11 instructs the backup power storage device 23 to perform backup, it takes time for the management unit 38 to place the first current interruption device 39 in an energized state.

For this reason, when the vehicle ECU 11 according to the third embodiment determines that the driving situation requires preparation for a power failure of the auxiliary power storage device 22, it instructs the management unit 38 of the backup power storage device 23 to energize the first current interruption device 39. In the low-frequency mode, the operating clock is low but the management unit 38 of the backup power storage device 23 is active, so upon receiving the instruction, the management unit 38 of the backup power storage device 23 energizes the first current interruption device 39. The energization of the first current interruption device 39 of the backup power storage device 23 is an example of preparation.
If a power failure subsequently occurs in the auxiliary power storage device 22, the vehicle ECU 11 energizes the second current interruption device 40. Because the first current interruption device 39 of the backup power storage device 23 is already energized, the backup starts immediately when the second current interruption device 40 is energized.

According to the control method of embodiment 3, if it is determined that the driving conditions require preparation for a power failure of the auxiliary electric storage device 22, the first current interruption device 39 is energized, thereby enabling backup to begin in a shorter time than if the first current interruption device 39 were energized after a power failure of the auxiliary electric storage device 22 occurs.

According to the control method of embodiment 3, when a power failure occurs, the second current interruption device 40 is energized, allowing the backup power storage device 23 to back up the auxiliary power storage device 22.

<Fourth Embodiment>
A fourth embodiment will be described with reference to Fig. 7. The fourth embodiment is a modification of the first to third embodiments. Here, the fourth embodiment will be described as a modification of the first embodiment.
7, the backup power storage device 23 according to the fourth embodiment includes a heater 41 (an example of a heating unit) therein for heating the battery cell 30A. The power supplied to the heater 41 is supplied from the battery cell 30A.

The management unit 38 of the backup power storage device 23 according to the fourth embodiment also transitions to the low frequency mode when the auxiliary power storage device 22 is not backed up.
When the vehicle ECU 11 according to the fourth embodiment determines that the driving situation requires preparation for a power failure of the auxiliary power storage device 22, it instructs the management unit 38 of the backup power storage device 23 to heat the battery cells 30A. Upon receiving the instruction, the management unit 38 of the backup power storage device 23 energizes the heater 41 to heat the battery cells 30A. Heating the battery cells 30A is an example of preparation.

If a power failure subsequently occurs in the auxiliary power storage device 22, the vehicle ECU 11 instructs the management unit 38 of the backup power storage device 23 to perform backup. Because the voltage of the battery cell 30A of the backup power storage device 23 has already risen to the rated voltage due to heating, backup at the rated voltage begins immediately when the first current interrupter 39 is energized.

According to the control method of embodiment 4, if it is determined that the driving conditions require preparation for a power failure of the auxiliary power storage device 22, the battery cell 30A is heated, so that backup at the rated voltage can be started in a short time when a power failure occurs in the auxiliary power storage device 22.

<Embodiment 5>
The fifth embodiment is a modification of the first to fourth embodiments. Here, it will be described as a modification of the first embodiment.
The management unit 38 of the backup power storage device 23 according to the fifth embodiment also transitions to the low frequency mode when the auxiliary power storage device 22 is not backed up.
In the fifth embodiment, the communication speed between the first communication unit 11D of the vehicle ECU 11 and the second communication unit 38C of the backup power storage device 23 is variable. When the auxiliary power storage device 22 is not being backed up, the management unit 38 of the backup power storage device 23 slows the communication speed of the second communication unit 38C below the reference speed in order to reduce power consumption.

When the vehicle ECU 11 according to the fifth embodiment determines that the driving situation requires preparation for a power failure of the auxiliary power storage device 22, it instructs the management unit 38 of the backup power storage device 23 to return the communication speed of the second communication unit 38C to the reference speed. Upon receiving this instruction, the management unit 38 of the backup power storage device 23 returns the communication speed of the second communication unit 38C to the reference speed. In other words, the management unit 38 of the backup power storage device 23 increases the communication speed of the second communication unit 38C. Returning to the reference speed is an example of preparation.

If a power failure subsequently occurs in the auxiliary power storage device 22, the vehicle ECU 11 instructs the management unit 38 to perform backup. Upon receiving the backup instruction, the management unit 38 switches the first current interruption device 39 to a conducting state, thereby starting backup. Because the communication speed between the first communication unit 11D and the second communication unit 38C has returned to the reference speed, when the auxiliary power storage device 22 instructs the management unit 38 of the backup power storage device 23 to perform backup, the backup instruction is received by the management unit 38 of the backup power storage device 23 in a short period of time. Therefore, when a power failure occurs in the auxiliary power storage device 22, the backup power storage device 23 can start backup in a short period of time.

According to the control method of embodiment 5, if it is determined that the driving situation requires preparation for a power failure of the auxiliary power storage device 22, the communication speed between the vehicle ECU 11 and the management unit 38 of the backup power storage device 23 is returned to the reference speed. This reduces the time it takes for the management unit 38 of the backup power storage device 23 to receive a backup command when a power failure of the auxiliary power storage device 22 occurs. Therefore, backup can be started in a short time when a power failure of the auxiliary power storage device 22 occurs.

<Embodiment 6>
The sixth embodiment is a modification of the first to fifth embodiments. Here, it will be described as a modification of the first embodiment.
After canceling the preparation state in S108 shown in FIG. 4 , the vehicle ECU 11 according to the sixth embodiment instructs the management unit 38 of the backup power storage device 23 to discharge. When the management unit 38 of the backup power storage device 23 receives the discharge instruction, it energizes the first current interrupting device 39. This causes power to be supplied from the backup power storage device 23 to the auxiliary machinery 26, and the backup power storage device 23 is discharged (an example of a process for reducing the state of charge). When the SOC of the backup power storage device 23 drops to, for example, 50%, the management unit 38 of the backup power storage device 23 switches the first current interrupting device 39 to an interrupted state, thereby stopping the discharge.

According to the control method of the sixth embodiment, when the driving conditions are no longer such that preparation for a power failure of the auxiliary storage device 22 is necessary, the SOC of the backup storage device 23 is reduced, thereby suppressing deterioration of the backup storage device 23.

<Other Embodiments>
The technology disclosed in this specification is not limited to the embodiments described above and in the drawings, and for example, the following embodiments are also included in the technical scope disclosed in this specification.

(1) In the above embodiment, the vehicle 1 is an electric vehicle, but the vehicle 1 may also be an engine vehicle. In the case of an engine vehicle, the auxiliary storage device 22 is used as a starting storage device that supplies power to a starter motor provided in an engine starting device of the vehicle 1, and is also used as an auxiliary storage device that supplies power to the auxiliary devices 26. In the case of an engine vehicle, the auxiliary storage device 22 and the backup storage device 23 are charged by a vehicle generator (alternator). The vehicle 1 may also be a hybrid vehicle.

(2) In the above embodiment, the vehicle 1 is an autonomous vehicle, but the vehicle 1 may also be a manually driven vehicle.

(3) In the above embodiment, the driving conditions for which preparation for a power failure is required are exemplified by (a) to (g), but the driving conditions for which preparation for a power failure is required are not limited to these. For example, driving conditions for which preparation for a power failure is required may be driving in an urban area and on a road with people on the sidewalk, or driving at night and in the rain. Alternatively, because the risk of a power failure in the auxiliary power storage device 22 is high when the vehicle 1 is traveling at high speeds, a driving condition for which preparation for a power failure is required may be a vehicle speed at or above a predetermined value (e.g., 80 km/h).

(4) In the above embodiment, the current driving situation is used as an example of the driving situation of vehicle 1, but the driving situation of vehicle 1 may also be a driving situation in the near future. For example, if vehicle 1 is scheduled to enter an urban area in the near future on the set driving route, the driving situation in the near future of vehicle 1 is a driving situation in which preparations should be made for a power failure of the auxiliary power storage device 22. For this reason, backup preparations may be made before entering an urban area. Alternatively, if the start of the nighttime hours is scheduled for the near future, backup preparations may be made before the start of the nighttime hours.

(5) In the above-described second embodiment, a case where a backup is prepared when an abnormality in the auxiliary storage device 22 is predicted is described as an example. In contrast, even if an abnormality in the auxiliary storage device 22 is predicted, a backup may not be prepared if the vehicle 1 is not traveling. In other words, a backup may be prepared when an abnormality in the auxiliary storage device 22 is predicted and the vehicle 1 is traveling.

(6) In the above second embodiment, abnormalities in the auxiliary power storage device 22 are described using examples such as SOC abnormalities (overcharging, overdischarging), voltage abnormalities, and temperature abnormalities, but abnormalities in the auxiliary power storage device 22 are not limited to these. For example, abnormalities in the SOH (State of Health), which indicates the health state or degradation state of the auxiliary power storage device 22, may also be present.

(7) In the above-described second embodiment, if an abnormality in the auxiliary power storage device 22 is predicted, the management unit 38 of the auxiliary power storage device 22 notifies the vehicle ECU 11 that an abnormality is predicted. In contrast, the management unit 38 of the auxiliary power storage device 22 may send an activation signal to the management unit 38 of the backup power storage device 23 instead of notifying the vehicle ECU 11 that an abnormality is predicted. Sending an activation signal to the management unit 38 of the backup power storage device 23 activates the management unit 38 of the backup power storage device 23, thereby preparing the backup. Communication between the management unit 38 of the auxiliary power storage device 22 and the management unit 38 of the backup power storage device 23 may be performed via the vehicle ECU 11, or the management unit 38 of the auxiliary power storage device 22 and the management unit 38 of the backup power storage device 23 may communicate directly.

(8) In the above second embodiment, the management unit 38 of the auxiliary storage device 22 predicts an abnormality in the auxiliary storage device 22. However, information for predicting an abnormality in the auxiliary storage device 22 (such as a current value) may be transmitted to the vehicle ECU 11, and the vehicle ECU 11 may predict an abnormality in the auxiliary storage device 22.

(9) In the above fourth embodiment, an example was described in which the heater 41 was provided inside the backup power storage device 23. However, the heater 41 may be provided outside the backup power storage device 23 and in the vicinity of the backup power storage device 23. In this case, the auxiliary power storage device 22 may supply power to the heater 41, or the backup power storage device 23 may supply power to the heater 41.

(10) In the above-described fourth embodiment, the heater 41 is used to heat the battery cell 30A, but the method for heating the battery cell 30A is not limited to this. For example, in the first embodiment, the backup power storage device 23 is charged in S105. When the backup power storage device 23 is charged, the temperature of the battery cell 30A rises, and as a result, the battery cell 30A is heated.

(11) In the sixth embodiment described above, the SOC of the backup power storage device 23 is reduced by supplying power to the auxiliary machinery 26. However, a discharge resistor may be provided inside or outside the backup power storage device 23, and power may be discharged through the discharge resistor.

(12) In the above embodiment, some or all of the processing performed by the vehicle ECU 11 may be performed by the management unit 38 of the backup power storage device 23.

(13) In the above embodiment, the auxiliary storage device 22 and the backup storage device 23 are both rated at 12V. However, the ratings of the auxiliary storage device 22 and the backup storage device 23 are not limited to this. For example, the auxiliary storage device 22 may be rated at 24V and the backup storage device 23 may be rated at 12V. The auxiliary storage device 22 may be rated at 48V and the backup storage device 23 may be rated at 12V. The auxiliary storage device 22 may be rated at 48V and the backup storage device 23 may be rated at 24V. The auxiliary storage device 22 may be rated at 48V and the backup storage device 23 may be rated at 48V. If the rated voltage of the backup storage device 23 is lower than the rated voltage of the auxiliary storage device 22, the voltage is converted by a DC/DC converter.

(14) In the above embodiment, a lithium-ion secondary battery was used as an example of the storage element, but the storage element may also be a capacitor that involves an electrochemical reaction.

1 Vehicle 11 Vehicle ECU (an example of a control device or control unit)
22. Auxiliary power storage device (an example of a main power storage device)
23 Backup power storage device 26 Auxiliary equipment (an example of an electrical load)
30A battery cell (an example of a storage element)
31 BMU (an example of a management device or control unit)
39 First current interruption device 40 Second current interruption device 41 Heater (an example of a heating unit)

Claims (4)

A control method for a backup power storage device that backs up a main power storage device that supplies power to an electrical load mounted on a vehicle, comprising:
a determination step of determining whether the vehicle is in a driving state in which preparation for a power failure is required, in which power is not normally supplied from the main power storage device to the electrical load;
a preparation step of preparing the backup power storage device so that the backup power storage device can start backup in a short time when the power failure occurs, when the determination step determines that the driving situation is one in which preparation for the power failure is required;
Including,
The method for controlling a backup power storage device, wherein the driving situation for which preparation for a power failure is required is a situation in which an abnormality in the main power storage device is predicted or a driving situation in the near future. 2. A method for controlling a backup power storage device according to claim 1, comprising:
A control method for a backup storage device, in which a situation in which an abnormality in the main storage device is predicted is determined based on at least one of the SOC, current, voltage, temperature, and SOH of a storage element provided in the storage device. 2. A method for controlling a backup power storage device according to claim 1, comprising:
The method for controlling a backup power storage device, wherein the driving situation in the near future is at least one of a situation in which the vehicle will be driving on a congested road in the near future, a situation in which the vehicle will enter an urban area in the near future, a situation in which the vehicle will be driving at night in the near future, a situation in which the vehicle will be driving in the rain in the near future, a situation in which there are other vehicles around the vehicle in the near future, a situation in which the vehicle will be driving on a road with people on the sidewalk in the near future, and a situation in which the vehicle will be driving autonomously in the near future. A power supply system for a vehicle, comprising:
a main power storage device that supplies power to an electrical load mounted on the vehicle;
a backup power storage device that backs up the main power storage device;
A control unit;
Equipped with
The control unit
a determination process for determining whether the vehicle is in a driving state in which preparation for a power failure, in which power is not normally supplied from the main power storage device to the electrical load, is required;
a preparation process for preparing the backup power storage device so that the backup power storage device can start backup in a short time when the power failure occurs, when the determination process determines that the driving situation is one in which preparation for the power failure is required;
Run
The driving situation in which the power failure should be prepared for is a situation in which an abnormality in the main power storage device is predicted or a driving situation in the near future.
Vehicle power system.