JP7639287B2 - Method for controlling backup power storage device and vehicle power supply system - Google Patents

Description

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

Conventionally, vehicles are known that are equipped with 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 no longer able 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 vehicle that is equipped with a main battery (corresponding to a main power storage device) and a sub-battery (corresponding 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 charge stored in the sub-battery so that the amount of charge stored in the sub-battery after curve driving is equal to or greater than a threshold at which a specified fail operation is possible.

JP 2020-21706 A

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 in 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 electric load mounted on a vehicle, the control method including a determination step of determining whether the driving conditions of the vehicle are such that a power failure should be prepared for, in which the main power storage device will no longer normally supply power to the electric 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 the determination step determines that the driving conditions are such that a power failure should be prepared for.

This can improve 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 of the present invention; Schematic diagram of power supply system A block diagram showing an 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. 13 is a block diagram showing an 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 for a power failure are required in which power is no longer normally supplied from the main power storage device to the electrical load, and a preparation step of making preparations so that the backup power storage device can begin backup in a short period of time when the power failure occurs, if it is determined in the determination step that the driving conditions are such that preparations for the power failure are required.

"Vehicle driving conditions" are 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 of time" means that the time from when a power failure occurs in the main power storage device to when backup begins is shorter than in the case where the above-mentioned preparations are not made. "Power fail" 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 during the period from when a power failure occurs in the main power storage device to when backup begins, safety is reduced if backup cannot begin in a short period of 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 in order to start a backup. Since it takes a certain amount of time to prepare the backup, if the backup is not prepared, it may not be possible to start the backup in a short time if a power failure occurs in the main power storage device.

In the invention described in the aforementioned Patent Document 1, the sub-battery is charged before entering a curve. However, charging the sub-battery does not shorten the time from when a power failure occurs in the main battery until backup begins. In other words, the invention described in Patent Document 1 does not prepare for backup to begin in a short time when a power failure occurs in the main battery. 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 are such that it should be prepared for a power failure in which the main power storage device will no longer be able to normally supply power to the electrical load (hereinafter simply referred to as a "power failure of the main power storage device"), the backup power storage device is prepared to start backup in a short time when a power failure of the main power storage device occurs, so that backup can start in a short time when a power failure of the main power storage device occurs. 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 a power failure may be at least one of the following conditions: 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 driving mode.

When driving on a congested road, there is a higher possibility that there are other vehicles around the vehicle than when driving on a road that is not congested, and therefore, if a power failure occurs in the main power storage device and safe driving becomes difficult, there is a possibility that the vehicle may collide with another vehicle. Therefore, the risk is high when a power failure occurs in the main power storage device. For this reason, it can be said that a driving situation when driving on a congested road is 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 probability of there being many 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. Therefore, 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 turned off, the risk of a power failure in the main power storage device is higher than when driving during the day.
Since visibility is poorer when driving in the rain than when driving on a sunny day, when 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 and 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 that the vehicle may collide with the other vehicles. For this reason, the risk of a power failure in the main power storage device is higher than in a situation where 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. If a power failure occurs in the main power storage device and safe driving becomes difficult, there is a possibility of contact with people. For this reason, there is a high risk when a power failure occurs in the main power storage device.

In autonomous vehicles, if power supply to the electrical load is cut off 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 autonomously than when driving manually.

According to the above control method, the driving conditions in which the vehicle should be prepared for a power failure of the main power storage device are at least one of the following conditions: 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 driving mode, thereby improving safety in the event of a power failure of the main power storage device.

When driving at night, in the rain, or in autonomous driving mode, it is not necessarily likely that there are other vehicles or people around the vehicle; however, when driving on congested roads, in urban areas, when there are other vehicles around the vehicle, and when driving on roads with people on the sidewalk, there is a high possibility that there are other vehicles or people around the vehicle. The invention described in Patent Document 1 mentioned above is intended to prevent fail operation from becoming impossible after driving around a curve, but sufficient consideration has not been given to improving the safety of third parties in the event of a power failure of the main battery.

In contrast, according to the above control method, if 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, the method prepares for a backup, improving the safety of not only the vehicle 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 method for controlling 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 for predicting an abnormality in the main power storage device, and a preparation step for preparing the backup power storage device to start backup in a short time in response to a power failure that prevents the main power storage device from normally supplying power to the electrical load when an abnormality is predicted in the prediction step.

The above preparation process includes not only the case where preparation is always performed when an abnormality is predicted, but also the case where preparation is performed when another condition is met in addition to the abnormality being predicted. For this reason, even if an abnormality is predicted, a backup may not be prepared.
According to the above control method, in response to prediction of an abnormality in the main power storage device, the backup power storage device prepares to start backup in a short time when a power failure occurs in the main power storage device, so that backup can start in a short time when a power failure occurs 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 storage device includes a storage element, a first current interruption device connected in series to the storage element, and a management device that operates with power supplied from the storage element, the management device setting the first current interruption device to a cut-off state when the main storage device is not being backed up, and setting the first current interruption device to a conductive state when the main storage device is being backed up, the management device transitioning to a power saving mode when the main 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 a decrease in the state of charge of the backup storage device due to minute dark currents flowing from the backup storage device to the electrical load.
According to the above control method, when the main power storage device is not backed up, the management device goes into a power saving mode. Since the management device operates using power supplied from the power storage element, the power consumption of the power storage element by the management device is also reduced when the management device goes into the power saving mode.

However, in the power saving mode, it takes longer for the management device to switch the first current interruption device to a conductive state than in the 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 a 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 storage device includes a storage element and a first current interruption device connected in series to the storage element, and the control method includes a step of bringing the first current interruption device into an interrupted state when the main storage device is not being backed up, and the first current interruption device may be brought into an energized state 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 a decrease in the state of charge of the backup storage device due to minute dark currents 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, when a contact switch such as a relay is used as the first current interruption device, it takes a long time of several tens to several hundreds of ms to switch from an interrupted state to an energized state. Even if the first current interruption device is a semiconductor switch such as a FET (Field Effect Transistor), a certain amount of time is required. For this reason, if the main storage device is switched to an energized state after a power failure occurs, backup cannot be started 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 first current interruption device is turned on, so that backup can be started in a shorter time than when the first current interruption device is turned on 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, so that the main storage device can be backed up by the backup storage device.

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

The temperature of the storage element of a backup power storage device may drop while in standby. If the temperature of the storage element is low, the output voltage drops. When backup starts, 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 includes a step of slowing down 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 in the preparation step, the communication speed between the control device and the management device may be returned 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 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, so that the time until the management device of the backup power storage device receives a backup instruction when a power failure of the main power storage device occurs can be shortened. Therefore, 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 one in which preparation for a power failure is required.

If the state of charge (SOC) of the backup power storage device is low, there is a possibility that the backup power storage device will not be able to supply sufficient power to an electric load when backup power is required.
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 backup power storage device is charged in advance, thereby increasing the likelihood 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 when the driving conditions of the vehicle are no longer those that require preparation for the power fail after the preparation step.

In order to maintain a state in which the backup is prepared (prepared state), power from the backup storage device or the main storage device may be consumed. 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 required, the prepared state is cancelled, so that power consumption from the backup storage device or the main storage device can be reduced.

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

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 it is necessary to prepare for a power failure of the main storage device, the state of charge of the backup storage device is lowered, 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.

According to the above control method, the backup storage device is charged in advance in response to a predicted abnormality in the main storage device, increasing the likelihood that sufficient power can be supplied to the electrical load when a backup is required.

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

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

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

According to the above control method, when an abnormality in the main storage device is no longer predicted, the charge state of the backup storage device is lowered, 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>
A 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 11 (electronic control unit: electronic control unit), a memory unit 12, various sensors 13, an autonomous driving control unit 14, an electric motor 25 that drives the vehicle 1, auxiliary equipment 26 (an example of an electric load), a wireless communication unit 16, and a power supply system 17. The vehicle ECU 11 is an example of a control unit 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, etc. 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 of the satellite positioning systems. 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 automatic driving control unit 14 is a computer that controls automatic 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 automatic driving control unit 14 includes a CPU, a ROM, a RAM, etc. The ROM stores a control program and various data for the CPU to control the automatic driving.
The auxiliary devices 26 are devices that operate on electricity, and include electric power steering, electric brakes, headlights, wipers, an air conditioner, and the like.

The wireless communication unit 16 is a circuit for receiving traffic information (traffic jam information, accident/broken-down vehicle/construction information, speed regulation/lane regulation 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 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 for vehicles to wirelessly transmit and receive vehicle information such as their positions and speeds to each other in order 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 FIG. 2. The power supply system 17 includes a drive storage device 21 that supplies power to the electric motor 25, an auxiliary storage device 22 (an example of a main storage device) that supplies power to the auxiliary devices 26, a backup storage device 23 that backs up the auxiliary storage device 22, and a DC/DC converter 24. The vehicle ECU 11, the auxiliary storage device 22, and the backup storage device 23 are an example of a power supply system according to the first embodiment.

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 the DC/DC converter 24 by a power line separate from the auxiliary power storage device 22. The backup power storage device 23 does not need to supply power to all the auxiliary devices 26, but may supply power only to the minimum amount of auxiliary devices 26 required for safe driving.

The drive storage device 21 is a high-voltage storage device rated at, for example, 100 V. The auxiliary storage device 22 and the backup storage device 23 are rated at, for example, 12 V. When the auxiliary storage device 22 and the backup storage device 23 are charged while the vehicle 1 is traveling, they are 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.

The auxiliary storage device 22 may experience a power failure due to various causes. For example, if the auxiliary storage device 22 is excessively charged (overcharged) due to a failure of the DC/DC converter 24, or if the auxiliary storage device 22 is not charged and is excessively discharged (overdischarged) due to a failure of the DC/DC converter 24, the first current interrupt device 39 (see FIG. 3) described later may be in an interrupted state (open state, off state, open state), causing a power failure. Alternatively, a power failure may occur when the first current interrupt device 3 described later remains in an interrupted state due to a failure. Alternatively, a power failure may occur due to deterioration of the auxiliary storage device 22. Alternatively, a power failure may occur due to a break in the power line that supplies power from the auxiliary storage device 22 to the auxiliary devices 26.

(2) Electrical Configuration of Auxiliary Power Storage Device and Backup Power Storage Device The electrical configuration of the auxiliary power storage device 22 is substantially the same as the electrical configuration of the backup power storage device 23. Here, the backup power 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 a power line 33P, and the negative electrode side is connected to the negative electrode external terminal 34N via a power line 33N. The battery pack 30 has 12 battery cells 30A connected in three parallel configurations and four in series. In FIG. 3, the three battery cells 30A connected in parallel are represented by one battery symbol. The battery cells 30A are secondary batteries that can be repeatedly charged and discharged, and specifically, for example, lithium-ion secondary batteries.

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. The number of temperature sensors 37 may be only one.

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 FET (Field Effect Transistor) 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 an SOC estimation process and a protection process, 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. The SOC estimation process is a process for estimating the SOC of the backup power storage device 23. Methods for estimating the SOC include a method in which the current sensor 35 measures the current value at a predetermined time interval (e.g., 10 milliseconds) and estimates the SOC by adding or subtracting the measured current value from an initial value (current integration method), and a method in which the SOC is estimated from the open circuit voltage (OCV) of the backup power storage device 23.

The protection process is a process for protecting the backup storage device 23 from abnormalities. The management unit 38 determines that the backup storage device 23 is abnormal, for example, when the estimated SOC is equal to or higher than a predetermined upper limit (overcharging), when the SOC is equal to or lower than a predetermined lower limit (overdischarging), when the current value measured by the current sensor 35 is equal to or higher than a predetermined value (overcurrent), or when the temperature measured by the temperature sensor 37 is equal to or higher than a predetermined value. When the management unit 38 determines that the backup storage device 23 is abnormal, it protects the backup 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 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 auxiliary power storage device 22 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 interrupted state in order to suppress consumption of power of the backup power storage device 23 due to dark current flowing from the backup power storage device 23 to the auxiliary devices 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 activated, power will be consumed by the management unit 38. Therefore, in order to reduce power consumption, the management unit 38 switches to a sleep mode (an example of a power saving mode) after switching the first current interruption device 39 to an interrupted state. In the sleep mode, power supply to functions other than the function waiting for an external start-up signal is cut off. This reduces power consumption by the management unit 38.

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

A power failure of the auxiliary storage device 22 can be detected by an appropriate method. For example, the vehicle ECU 11 may determine that a power failure of the auxiliary storage device 22 has occurred when the current value of the current flowing from the auxiliary storage device 22 to the auxiliary devices 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 when the voltage of the auxiliary storage device 22 has dropped to or less than a predetermined value. Alternatively, when the management unit 38 of the auxiliary storage device 22 has put the first current interruption device 39 into an interrupted state by the protection process, the management unit 38 may notify the vehicle ECU 11 that the first current interruption device 39 has been put into an interrupted state. When the vehicle ECU 11 is notified by the auxiliary storage device 22 that the first current interruption device 39 has been put into an interrupted state, the vehicle ECU 11 may determine that a power failure of the auxiliary storage device 22 has occurred.

The management unit 38 of the backup power storage device 23 starts up when it receives a start-up signal from the vehicle ECU 11 (switching from sleep mode to normal mode). 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 is instructed to perform a backup, 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 storage device 23, if the management unit 38 is started after a power failure occurs in the auxiliary storage device 22, it takes time for the backup to start. For this reason, the vehicle ECU 11 repeatedly executes a judgment process at a predetermined time interval, such as an interval of 5 seconds, while the vehicle 1 is running to judge whether the current driving conditions of the vehicle 1 are driving conditions that require preparation for a power failure of the auxiliary storage device 22. The judgment process will be described later. The judgment process may be executed not only while the vehicle is running, 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 up the management unit 38 (an example of a preparation process or a preparation step). Starting up the management unit 38 is an example of preparation.
If a power failure occurs in the auxiliary power storage device 22 thereafter, since the management unit 38 of the backup power storage device 23 has already been activated, 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, as compared with a case in which 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 requires preparation for a power failure of the auxiliary power storage device 22.

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

The determination as to whether or not the vehicle's driving conditions correspond to the above-mentioned driving conditions will be described below.
(a) State of driving on a congested road The vehicle ECU 11 detects the vehicle's position by the GPS receiver, and receives congestion information from an intelligent road traffic system, a server on the Internet, etc. by the wireless communication unit 16. When 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 driving on a congested road.

The vehicle ECU 11 determines whether there are other vehicles around the vehicle by using the forward detection device, rear detection device, left side detection device, and right side detection device, as well as vehicle-to-vehicle communication via the wireless communication unit 16, and may also detect the speed of the vehicle using a vehicle speed sensor.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 for the determination.

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

(c) Night driving status 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 or not the vehicle is driving at night is not limited to these, and any appropriate method may be used.

(d) Driving in the Rain 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 position using the GPS receiver and may also receive weather information from an intelligent road transport 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 of 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 m around 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 by the vehicle ECU 11 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 m is one example. The radius within which the surroundings of the vehicle 1 are defined can be determined appropriately.
The vehicle ECU 11 may determine whether or not there is another vehicle around the vehicle 1 by vehicle-to-vehicle communication. The method for determining whether or not there is another vehicle around the vehicle 1 is not limited to the above, and the determination can be made by any appropriate method.

(f) A situation where 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 traveling on the left side of the road and keeps to the left. 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 the determination can be made by any appropriate method.

(g) Situation in which the vehicle is traveling in an automatic driving mode Generally, in an automatic driving vehicle, the driver of the vehicle 1 can switch between automatic driving and manual driving. When the vehicle is switched to automatic driving, the vehicle ECU 11 determines that the vehicle is traveling in an automatic driving mode.
Switching between automatic driving and manual driving can also be achieved by a method other than switching by the driver. For example, the vehicle ECU 11 may detect the driver's facial color, expression, posture, body temperature, etc., using a camera or other sensors when 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 may switch to automatic driving when it is determined 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 5 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 judges whether or not 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 judgment process or judgment step). If the vehicle ECU 11 judges 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 judges 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 or not the backup power storage device 23 is in backup mode. If the backup power storage device 23 is not in backup mode, the process proceeds to S104. If the backup power storage device 23 is in backup mode, 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 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 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 the backup power storage device 23 is in a ready state, the process proceeds to S107, and if the backup power storage device 23 is not in a ready state, the process ends.
In S107, the vehicle ECU 11 determines whether or not the backup power storage device 23 is in backup mode. If the backup power storage device 23 is not in backup mode, the process proceeds to S108. If the backup power storage device 23 is in backup mode, the process ends.
In S108, the vehicle ECU 11 instructs the backup power storage device 23 to cancel the preparation state. When the management unit 38 of the backup power storage device 23 receives the instruction to cancel, the management unit 38 switches the first current interruption device 39 to an interruption state, and then transitions to a sleep mode (an example of a process for canceling the preparation state). This cancels the preparation state.

The backup process will now 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 or not 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 step S203, the vehicle ECU 11 instructs the backup power storage device 23 to perform backup.
In step 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) Effect of the embodiment According to the control method for the 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 the auxiliary power storage device 22, the backup power storage device 23 prepares to start backup in a short time when a power failure occurs in the auxiliary power storage device 22, so that backup can be started in a short time when a power failure occurs in the auxiliary power storage device 22. This improves safety in the event of a power failure in the auxiliary power storage device 22.

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

According to the above control method, when 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 a conducting 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, so that there is a high possibility that sufficient power can be supplied to the auxiliary devices 26 when a backup is required.

According to the above control method, when the driving conditions are no longer such that preparation for a power failure of the auxiliary storage device 22 is required, the preparation state is cancelled (S108), so that power consumption of the backup storage device 23 can be reduced.

<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 above-mentioned SOC estimation process, 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 or prediction process). For example, it is assumed that an abnormality (overcharging) occurs when the SOC is 95% or more. 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 more. 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.

When an abnormality occurs in the auxiliary storage device 22, the first current interruption device 39 is shut off, so 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 so that the backup storage device 23 can start backup in a short time if a power failure occurs in the auxiliary storage device 22. This preparation is the same as in embodiment 1, so a description will be omitted.

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

According to the control method of the second embodiment, when 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 preparation is started after a power failure occurs in the auxiliary storage device 22. This improves safety when a power failure occurs in the auxiliary storage device 22.

According to the control method of the second embodiment, the backup power storage device 23 is charged in advance in response to a predicted abnormality in the auxiliary power storage device 22, so that there is a high possibility that sufficient power can be supplied to the auxiliary devices 26 when a backup is required.

According to the control method of the second embodiment, when an abnormality in the auxiliary storage device 22 is no longer predicted, the standby state is cancelled, so that power consumption in the backup storage device 23 can be reduced.

According to the control method of the second embodiment, 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>
A 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 lower than in the normal mode, rather than to a sleep mode. Since the operating clock is lower in the 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 turn on 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 when the management unit 38 of the backup power storage device 23 receives the instruction, it turns on the first current interruption device 39. Turning on 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. Since 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 the third embodiment, when it is determined that the driving situation requires preparation for a power failure of the auxiliary storage device 22, the first current interruption device 39 is energized, so that backup can be started in a shorter time than when the first current interruption device 39 is energized after a power failure of the auxiliary storage device 22 occurs.

According to the control method of the third embodiment, when a power failure occurs, the second current interruption device 40 is energized, so that the auxiliary storage device 22 can be backed up by the backup storage device 23.

<Embodiment 4>
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) for heating the battery cell 30A therein. Electric power supplied to the heater 41 is supplied by 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 being 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 cell 30A. Upon receiving the instruction, the management unit 38 of the backup power storage device 23 energizes the heater 41 to heat the battery cell 30A. Heating the battery cell 30A is an example of preparation.

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

According to the control method of the fourth embodiment, when it is determined that the driving conditions require preparation for a power failure of the auxiliary 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 storage device 22.

<Embodiment 5>
The fifth embodiment is a modification of the first to fourth embodiments. Here, the fifth embodiment 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 being 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 makes the communication speed of the second communication unit 38C slower than a reference speed in order to suppress 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 storage device 22, it instructs the management unit 38 of the backup storage device 23 to return the communication speed of the second communication unit 38C to the reference speed. Upon receiving the instruction, the management unit 38 of the backup 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 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 storage device 22, the vehicle ECU 11 instructs the management unit 38 to perform a backup. When the management unit 38 receives the backup instruction, it switches the first current interruption device 39 to a conducting state. This starts the 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 storage device 22 instructs the management unit 38 of the backup storage device 23 to perform a backup, the backup instruction is received by the management unit 38 of the backup storage device 23 in a short time. Therefore, when a power failure occurs in the auxiliary storage device 22, the backup storage device 23 can start a backup in a short time.

According to the control method of the fifth embodiment, when it is determined that the driving situation requires preparation for a power failure of the auxiliary storage device 22, the communication speed between the vehicle ECU 11 and the management unit 38 of the backup storage device 23 is returned to the reference speed, so that the time until the management unit 38 of the backup storage device 23 receives a backup instruction when a power failure of the auxiliary storage device 22 occurs can be shortened. Therefore, when a power failure of the auxiliary storage device 22 occurs, backup can be started in a short time.

<Embodiment 6>
The sixth embodiment is a modification of the first to fifth embodiments. Here, the sixth embodiment 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 is instructed to discharge, it sets the first current interrupt device 39 to a conducting state. As a result, power is 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 of lowering 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 stops discharging by setting the first current interrupt device 39 to a cut-off state.

According to the control method of the sixth embodiment, when the driving conditions are no longer such that it is necessary to prepare for a power failure of the auxiliary storage device 22, 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 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 be a hybrid vehicle.

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

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

(4) In the above embodiment, the current driving condition is described as an example of the driving condition of vehicle 1, but the driving condition of vehicle 1 may be a driving condition in the near future. For example, if vehicle 1 will enter an urban area in the near future on the set driving route, the driving condition of vehicle 1 in the near future is a driving condition that requires preparation for a power failure of the auxiliary power storage device 22. For this reason, a backup may be prepared before entering the urban area. Alternatively, if the start time of the nighttime period is in the near future, a backup may be prepared before the start time of the nighttime period.

(5) In the above embodiment 2, 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, the abnormality of the auxiliary storage device 22 is described by taking as examples an abnormality in the SOC (overcharging, overdischarging), an abnormality in voltage, an abnormality in temperature, etc., but the abnormality of the auxiliary storage device 22 is not limited to these. For example, the abnormality may be an abnormality in the SOH (State of Health) indicating the health state or deterioration state of the auxiliary storage device 22.

(7) In the above-mentioned second embodiment, when an abnormality in the auxiliary storage device 22 is predicted, the management unit 38 of the auxiliary storage device 22 notifies the vehicle ECU 11 that an abnormality is predicted. In contrast, the management unit 38 of the auxiliary storage device 22 may send a start signal to the management unit 38 of the backup storage device 23 instead of notifying the vehicle ECU 11 that an abnormality is predicted. When a start signal is sent to the management unit 38 of the backup storage device 23, the management unit 38 of the backup storage device 23 starts up, and a backup is prepared. The communication between the management unit 38 of the auxiliary storage device 22 and the management unit 38 of the backup storage device 23 may be performed via the vehicle ECU 11, or the management unit 38 of the auxiliary storage device 22 and the management unit 38 of the backup storage device 23 may communicate directly.

(8) In the above embodiment 2, 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, the heater 41 is 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 embodiment 4, the heater 41 is used to heat the battery cell 30A, but the method of heating the battery cell 30A is not limited to this. For example, in embodiment 1, 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 increases, and as a result, the battery cell 30A is heated.

(11) In the above sixth embodiment, 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 the backup power storage device 23 may be discharged through the discharge resistor.

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

(13) In the above embodiment, the rated voltage of the auxiliary storage device 22 and the backup storage device 23 is 12V. However, the rated voltage of the auxiliary storage device 22 and the backup storage device 23 is not limited to this. For example, the rated voltage of the auxiliary storage device 22 may be 24V and the rated voltage of the backup storage device 23 may be 12V. The rated voltage of the auxiliary storage device 22 may be 48V and the rated voltage of the backup storage device 23 may be 12V. The rated voltage of the auxiliary storage device 22 may be 48V and the rated voltage of the backup storage device 23 may be 24V. The rated voltage of the auxiliary storage device 22 may be 48V and the rated voltage of the backup storage device 23 may be 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 is used as an example of the storage element, but the storage element may be a capacitor that involves an electrochemical reaction.

1 Vehicle 11 Vehicle ECU (an example of a control device or control unit)
22. Storage device for auxiliary equipment (an example of a main 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 (11)

A method for controlling a backup power storage device that backs up a main power storage device that supplies power to an electric load mounted on a vehicle, comprising:
a determination step of determining whether or not a driving condition of the vehicle is a driving condition in which a power failure should be prepared for when power is not normally supplied from the main power storage device to the electric 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 should be performed ;
A method for controlling a backup power storage device, comprising: 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 conditions for which power failure should be prepared are at least one of a condition in which the vehicle is traveling on a congested road, a condition in which the vehicle is traveling in an urban area, a condition in which the vehicle is traveling at night, a condition in which the vehicle is traveling in the rain, a condition in which there are other vehicles around the vehicle, a condition in which the vehicle is traveling on a road with people on the sidewalk, and a condition in which the vehicle is traveling in autonomous driving mode. A method for controlling the backup power storage device according to claim 1 or 2 , comprising:
The backup power storage device is
A storage element;
A first current interruption device connected in series to the storage element;
a management device that operates using power supplied from the storage element, the management device setting the first current interruption device in an interrupted state when the main storage device is not being backed up, and setting the first current interruption device in an energized state when the main storage device is being backed up;
Equipped with
the management device transitions to a power saving mode when the main power storage device is not backed up;
In the control method, the management device is caused to transition to a normal mode in the preparation step. A method for controlling the backup power storage device according to claim 1 or 2 , comprising:
The backup power storage device is
A storage element;
A first current interruption device connected in series to the storage element;
Equipped with
The control method includes:
a step of bringing the first current interruption device into an interrupted state when the main power storage device is not backed up;
The method for controlling a backup power storage device, wherein the preparation step brings the first current interruption device into an energized state. A method for controlling a backup power storage device according to claim 4 , comprising the steps of:
a second current interruption device is provided between the electric load and the backup power storage device;
The control method includes a step of placing the second current interruption device in a conducting state when the power failure occurs. A method for controlling the backup power storage device according to any one of claims 1 to 5 , comprising:
The method for controlling a backup power storage device, wherein in the preparation step, a power storage element included in the backup power storage device is heated. A method for controlling the backup power storage device according to any one of claims 1 to 6 , comprising:
a step of slowing down a 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,
The method for controlling a backup power storage device, wherein in the preparation step, the communication speed between the control device and the management device is returned to the reference speed. A method for controlling the backup power storage device according to claim 1 or 2, comprising:
The method for controlling a backup power storage device includes the step of charging the backup power storage device when it is determined in the determination step that the driving situation is one in which preparation for a power failure should be made. A method for controlling the backup power storage device according to claim 1 or 2, comprising:
A method for controlling a backup power storage device, comprising a step of canceling the preparation state of the backup power storage device when, after preparation in the preparation step, the driving conditions of the vehicle are no longer driving conditions that require preparation for a power fail. A method for controlling the backup power storage device according to claim 1 or 2, comprising:
A method for controlling a backup power storage device, comprising a step of discharging the backup power storage device to reduce its state of charge when, after preparation in the preparation step, the driving conditions of the vehicle are no longer driving conditions that require preparation for a power fail. 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 is
a determination process for determining whether or not a driving condition of the vehicle is a driving condition in which a power failure in which power is not normally supplied from the main power storage device to the electric load should be prepared;
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 should be performed ;
to run the vehicle's power system.

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