Method for controlling backup power storage device and vehicle power supply system

Abstract

To provide a control method for a backup power storage device and a power supply system for a vehicle that can improve safety in an event of a power failure of a main power storage device.SOLUTION: The control method for a backup power storage device backs up a power storage device for an auxiliary device (main power storage device) that supplies power to the auxiliary device installed in a vehicle. The control method includes a determination step S102 for determining whether the driving conditions of the vehicle are such that the vehicle should be prepared for a power failure in which power is not normally supplied to the auxiliary device from the power storage device for the auxiliary device and a preparation process S104 for preparing the backup power storage device to start backing up in a short time in an event of a power failure of an auxiliary power storage device 22 if the determination step determines that the driving conditions are such that the system should be prepared for power failures.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a control method for a backup power storage device and a power supply system for a vehicle. [Background technology]

[0002] Conventionally, there is known a vehicle that includes 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).

[0003] Specifically, the vehicle described in Patent Document 1 is an autonomous driving compatible vehicle, and 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 charge stored in the sub-battery so that the charge stored in the sub-battery after curve driving is equal to or greater than a threshold value that allows a predetermined fail-operation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-21706 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the vehicle control device described in Patent Document 1 above has room for improvement in terms of improving safety in the event of a power failure of the main battery.

[0006] This specification discloses a technique for improving safety in the event of a power failure in a main power storage device. [Means for solving the problem]

[0007] 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 including: 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 making preparations so that the backup power storage device 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. Effect of the Invention

[0008] This can improve safety in the event of a power failure in the main power storage device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing an electrical configuration of a vehicle according to a first embodiment. [Diagram 2] Schematic diagram of power supply system [Diagram 3] A block diagram showing an electrical configuration of a backup power storage device. [Figure 4] Flowchart of backup preparation process [Diagram 5] Backup process flowchart [Figure 6] Schematic diagram of a power supply system according to a third embodiment. [Figure 7] FIG. 13 is a block diagram showing an electrical configuration of a backup power storage device according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (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 a driving condition of the vehicle is one 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, and a preparation step of making preparations so that the backup power storage device can start backup in a short period of time when the power failure occurs if it is determined in the determination step that the driving condition is one in which preparation for the power failure is required.

[0011] The "vehicle driving conditions" are not limited to the current driving conditions, and may be driving conditions in the near future. "Backing up the main power storage device" means supplying power to an electric 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 starts is shorter than in the case where the above-mentioned preparations are not made. "Power fail" can also be rephrased as "power supply failure."

[0012] 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 until 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.

[0013] The inventors of the present application have found that a backup power storage device may need to be prepared in order to start a backup. Since the preparation for the backup takes a certain amount of time, if the backup is not prepared, it may not be possible to start the backup in a short time when a power failure occurs in the main power storage device.

[0014] In the invention described in the above-mentioned 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 starts. In other words, the invention described in Patent Document 1 does not prepare to start backup in a short time when a power failure occurs in the main battery. For this reason, there is room for improvement in improving safety when a power failure occurs in the main battery.

[0015] According to the above control method, when it is determined that the vehicle is in a driving state in which it is necessary to prepare for a power failure in which the main power storage device is no longer able to normally supply power to the electric 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 when a power failure of the main power storage device occurs.

[0016] (2) According to one aspect of the present invention, the driving conditions in which the vehicle should be prepared for power failure may be at least one of a condition in which the vehicle is driving on a congested road, a condition in which the vehicle is driving in an urban area, a condition in which the vehicle is driving at night, a condition in which the vehicle is driving in the rain, a condition in which there are other vehicles around the vehicle, a condition in which the vehicle is driving on a road with people on the sidewalk, and a condition in which the vehicle is driving autonomously.

[0017] 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 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 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 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.

[0018] 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.

[0019] 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.

[0020] 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 the vehicle is running in autonomous driving mode than when the vehicle is running in manual driving mode.

[0021] According to the above control method, driving conditions in which power failure of the main power storage device should be prepared for are at least one of the following conditions: 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 driving mode, thereby improving safety in the event of power failure of the main power storage device.

[0022] While it is not necessarily true that there is a high possibility of other vehicles or people around the vehicle when driving at night, in the rain, or in autonomous driving mode, there is a high possibility of other vehicles or people around the vehicle 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. The invention described in Patent Document 1 above is intended to prevent the failure of fail operation after driving around a curve, but has not been fully considered in terms of improving the safety of third parties in the event of a power failure of the main battery.

[0023] In contrast, according to the above control method, 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, the safety of not only the vehicle occupants but also third parties around the vehicle is improved, thereby ensuring safety from a more comprehensive perspective than the invention described in Patent Document 1.

[0024] (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 to be able to 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.

[0025] 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.

[0026] (4) According to one aspect of the present invention, the backup energy storage device includes a storage element, a first current interruption device connected in series to the storage element, and a management device operated by power supplied from the storage element, the management device placing the first current interruption device in an interrupted state when the main energy storage device is not being backed up, and placing the first current interruption device in an energized state when the main energy storage device is being backed up, the management device transitioning to a power saving mode when the main energy storage device is not being backed up, and the control method may transition the management device to a normal mode in the preparation step.

[0027] According to the above control method, the first current interruption device is set to an interrupted state when the main storage device is not being backed up, 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.

[0028] However, in the power saving mode, it takes longer for the management device to switch the first current interruption device to an energized 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 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.

[0029] (5) According to one aspect of the present invention, the backup energy 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 energy storage device is not being backed up, and the first current interruption device may be brought into an energized state in the preparation step.

[0030] According to the above control method, the first current interruption device is set to an interrupted state when the main storage device is not being backed up, 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, 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 main power 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.

[0031] (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 bringing the second current interruption device into an energized state when the power failure occurs.

[0032] According to the above control method, when a power failure occurs, the second current interruption device is brought into a conducting state, whereby the main power storage device can be backed up by the backup power storage device.

[0033] (7) According to one aspect of the present invention, in the preparation step, a power storage element included in the backup power storage device may be heated.

[0034] The temperature of the storage element of a backup power storage device may drop during 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.

[0035] (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.

[0036] 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.

[0037] (9) According to one aspect of the present invention, the method may include charging the backup power storage device when the determining step determines that the driving situation is one in which preparation for a power fail is required.

[0038] If the state of charge (SOC) of a 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 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.

[0039] (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, after preparation in the preparation step, the driving conditions of the vehicle are no longer those that require preparation for a power fail.

[0040] In order to maintain a state in which the backup is prepared (preparation state), power from the backup power storage device or the main power storage device may be consumed. According to the above control method, when the driving situation is no longer one in which preparation for a power failure of the main power storage device is required, the preparation state is cancelled, so that power consumption of the backup power storage device or the main power storage device can be suppressed.

[0041] (11) According to one aspect of the present invention, the method may include a step of discharging the backup power storage device to reduce a state of charge when, after preparation in the preparation step, the driving conditions of the vehicle are no longer those that require preparation for a power fail.

[0042] A power storage device is prone to degradation if it is 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 power storage device, the state of charge of the backup power storage device is lowered, thereby suppressing degradation of the backup power storage device.

[0043] (12) According to one aspect of the present invention, the method may include charging the backup power storage device in response to an abnormality being predicted in the prediction step.

[0044] 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, thereby increasing the likelihood that sufficient power can be supplied to the electrical load when backup is needed.

[0045] (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 when, after preparation in the preparation step, no abnormality in the main power storage device is foreseen.

[0046] According to the above control method, when an abnormality in the main power storage device is no longer predicted, the standby state is cancelled, so that power consumption in the backup power storage device or the main power storage device can be reduced.

[0047] (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 when, after preparation in the preparation step, no abnormality in the main storage device is foreseen.

[0048] According to the above control method, when an abnormality in the main power storage device is no longer predicted, the state of charge of the backup power storage device is lowered, thereby making it possible to suppress deterioration of the backup power storage device.

[0049] 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.

[0050] <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.

[0051] (1) Vehicle electrical configuration 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), 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 electric 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.

[0052] The vehicle ECU 11 is a computer that controls each part of the vehicle 1. The vehicle ECU 11 includes 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.

[0053] 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 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 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.

[0054] 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, on the left side, and on the right side 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.

[0055] 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 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, air conditioners, etc.

[0056] 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.) around the vehicle from an 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.

[0057] 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.

[0058] The power supply system 17 will be described with reference to Fig. 2. The power supply system 17 includes a driving power storage device 21 that supplies power to an electric motor 25, an auxiliary power storage device 22 (an example of a main power storage device) that supplies power to auxiliary devices 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 the first embodiment.

[0059] The backup power storage device 23 is a redundant system of 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 that of the auxiliary power storage device 22. The backup power storage device 23 does not need to supply power to all the auxiliary devices 26, and may supply power only to the minimum amount of the auxiliary devices 26 required for safe driving.

[0060] The driving power storage device 21 is a high-voltage power storage device rated at, for example, 100 V. The auxiliary power storage device 22 and the backup power storage device 23 are rated at, for example, 12 V. When the auxiliary power storage device 22 and the backup power storage device 23 are charged while the vehicle 1 is traveling, they are charged by the driving power storage device 21. When these power storage devices are charged by the driving power storage device 21, the voltage is converted by the DC / DC converter 24.

[0061] The auxiliary power storage device 22 may experience a power failure due to various causes. For example, if the auxiliary power storage device 22 is excessively charged (overcharged) due to a failure of the DC / DC converter 24, or if the auxiliary power storage device 22 is not charged and is excessively discharged (overdischarged) due to a failure of the DC / DC converter 24, a first current interrupting 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 a first current interrupting device 3 described later remains in an interrupted state due to a failure. Alternatively, a power failure may occur when the auxiliary power storage device 22 deteriorates. Alternatively, a power failure may occur when a power line that supplies power from the auxiliary power storage device 22 to the auxiliary devices 26 is broken.

[0062] (2) Electrical configuration of the auxiliary power storage device and the backup power storage device The electrical configuration of the auxiliary power storage device 22 is substantially the same as that 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 consisting of 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.

[0063] The positive electrode side of the battery pack 30 is connected to a positive electrode external terminal 34P via a power line 33P, and the negative electrode side is connected to a negative electrode external terminal 34N via a power line 33N. The battery pack 30 has 12 battery cells 30A connected in three parallel connections 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.

[0064] 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.

[0065] 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 by the management unit 38 between a conducting state (closed state, on state, closed state) and a blocking state (open state, off state, open state). 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.

[0066] The communication connector 32 is a connector to which a communication cable for communication between the management unit 38 and the vehicle ECU 11 is connected.

[0067] The following describes the SOC estimation process and protection process executed by management unit 38. The SOC estimation process is a process for estimating the SOC of backup power storage device 23. Methods for estimating the SOC include a method of measuring a current value at a predetermined time interval (such as 10 milliseconds) using current sensor 35 and adding or subtracting the measured current value from an initial value (current integration method), and a method of estimating the SOC from the open circuit voltage (OCV) of backup power storage device 23.

[0068] The protection process is a process for protecting the backup power storage device 23 from an abnormality. The management unit 38 determines that the backup power storage device 23 is abnormal when, for example, the estimated SOC is equal to or higher than a predetermined upper limit (overcharging), the SOC is equal to or lower than a predetermined lower limit (overdischarging), the current value measured by the current sensor 35 is equal to or higher than a predetermined value (overcurrent), or 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 power storage device 23 is abnormal, it protects the backup power storage device 23 from the abnormality by setting the first current interruption device 39 to an interrupted state. The abnormalities described above are merely examples, and the abnormality of the backup power storage device 23 is not limited to these.

[0069] (3) Backup using a 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.

[0070] As described 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 is consumed by the management unit 38. Therefore, in order to reduce power consumption, the management unit 38 transitions to a sleep mode (an example of a power saving mode) after the first current interruption device 39 is switched to an interrupted state. In the sleep mode, power supply to functions other than the function waiting for an external activation signal is cut off. This reduces power consumption by the management unit 38.

[0071] The vehicle ECU 11 will be described with reference to Fig. 1. The vehicle ECU 11 monitors the auxiliary power storage device 22, and when a power failure occurs in the auxiliary power storage device 22, transmits a start-up signal to the management unit 38 of the backup power storage device 23 via the first communication unit 11D. Although details will be described later, there are also cases where the vehicle ECU 11 transmits a start-up signal to the management unit 38 of the backup power storage device 23 even when a power failure does not occur in the auxiliary power storage device 22.

[0072] A power failure of the auxiliary power 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 power storage device 22 has occurred when the current value of the current flowing from the auxiliary power 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 power storage device 22 has occurred when the voltage of the auxiliary power storage device 22 has dropped to or less than a predetermined value. Alternatively, when the management unit 38 of the auxiliary power 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 power 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 power storage device 22 has occurred.

[0073] The management unit 38 of the backup power storage device 23 starts up (shifts 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 backup. When the management unit 38 of the backup power storage device 23 is instructed to perform backup, it switches the first current interruption device 39 of the backup power storage device 23 to a conducting state. This starts the backup.

[0074] However, since it takes a certain amount of time to start up management unit 38 of backup power storage device 23, if management unit 38 is started after a power failure occurs in auxiliary power storage device 22, it takes time until backup starts. For this reason, vehicle ECU 11 repeatedly executes a determination process at a predetermined time interval, such as an interval of 5 seconds, while vehicle 1 is running to determine whether or not the current driving situation of vehicle 1 is a driving situation in which power failure of auxiliary power storage device 22 should be prepared. The determination process will be described later. The determination process may be executed not only while vehicle 1 is running, but also while vehicle 1 is stopped.

[0075] 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 the case where the management unit 38 is activated after a power failure occurs in the auxiliary power storage device 22.

[0076] (3-1) Judgment processing The vehicle ECU 11 determines whether the current driving conditions of the vehicle 1 correspond to at least one of the following (a) to (g), and if so, determines that the driving conditions require preparation for a power failure of the auxiliary power storage device 22.

[0077] (a) Driving on a congested road (b) Driving in urban areas (c) Driving at night (d) Driving in the rain (e) Vehicle 1 is surrounded by other vehicles (f) Driving on a road where people are walking on the sidewalk (g) Situation when driving autonomously

[0078] The determination as to whether or not the vehicle's driving conditions correspond to the above-mentioned driving conditions will be described below. (a) 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. If the detected vehicle position is included in a congestion section indicated by the received congestion information, the vehicle ECU 11 determines that the vehicle is traveling on a congested road.

[0079] 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 by a vehicle speed sensor.If there are other vehicles around the vehicle and the vehicle speed of the vehicle is equal to or lower than a predetermined speed, the vehicle ECU 11 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.

[0080] (b) Driving in urban areas The vehicle ECU 11 detects the vehicle 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 traveling in an urban area. The method of judging whether the vehicle is traveling in an urban area is not limited to this, and any other appropriate method can be used.

[0081] (c) Driving at night When the headlights of the vehicle 1 are turned on / off, a corresponding signal is sent to the vehicle ECU 11. When the headlights are on, the vehicle ECU 11 determines that the vehicle is driving at night. The nighttime period (start time and end time of the nighttime period) may be set in advance. The vehicle ECU 11 may determine that the vehicle is driving at night if 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.

[0082] (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 traveling 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 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 of determining whether or not the vehicle is traveling in rainy weather is not limited to these, and any appropriate method may be used.

[0083] (e) There are other vehicles around the vehicle. The vehicle ECU 11 detects other vehicles around the vehicle 1 (for example, within a 30 m radius from the vehicle 1) using the forward 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 are other vehicles around the vehicle 1. The above-mentioned radius of 30 m is one example. The radius within a certain number of meters from the vehicle itself that is defined as the periphery of the vehicle 1 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 these, and the determination can be made by any appropriate method.

[0084] (f) Driving on a road where people are walking on the sidewalk Here, an example will be described in which the vehicle 1 drives 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 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.

[0085] (g) Situation when driving autonomously Generally, in an autonomous vehicle, the driver of the vehicle 1 can switch between autonomous driving and manual driving. When the vehicle is switched to autonomous driving, the vehicle ECU 11 determines that the vehicle is traveling in autonomous 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 complexion, facial expression, posture, body temperature, etc., using a camera or other sensor 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 switch to automatic driving when it determines that the driver is in poor health or drowsy.

[0086] (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 S101, the vehicle ECU 11 detects the running state 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.

[0087] In S103, the vehicle ECU 11 determines whether 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, vehicle ECU 11 transmits a start signal to backup power storage device 23 (an example of preparation processing or preparation step). However, if management unit 38 has already been activated and backup is already prepared, vehicle ECU 11 does not transmit the start signal. In the following description, the state in which management unit 38 is activated and 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 process of charging a backup power storage device).

[0088] In S106, 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 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 or not, and 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 management unit 38 of the backup power storage device 23 receives the instruction to cancel, the management unit 38 puts the first current interruption device 39 into 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.

[0089] 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 5 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.

[0090] 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 power storage device 23 for backup. 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.

[0091] (4) Effects of the embodiment According to the control method for the backup power storage device 23 of 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 when a power failure occurs in the auxiliary power storage device 22.

[0092] According to the above control method, the driving conditions in which power failure should be prepared for 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 the vehicle 1, 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.

[0093] According to the above control method, when it is determined that the driving situation requires preparation for a power failure of the auxiliary power storage device 22, the management unit 38 of the backup power storage device 23 is activated, so that the first current interruption device 39 can be brought into a conducting state in a short time when a power failure occurs in the auxiliary power storage device 22. Therefore, backup can be started in a short time when a power failure occurs in the auxiliary power storage device 22.

[0094] According to the above control method, when 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.

[0095] According to the above control method, when the driving conditions are no longer such that preparation for a power failure of the auxiliary power storage device 22 is required, the preparation state is cancelled (S108), so that power consumption of the backup power storage device 23 can be suppressed.

[0096] <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). 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 from, for example, 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.

[0097] When the auxiliary power storage device 22 becomes abnormal, the first current interruption device 39 enters an interrupted state, so that when an abnormality in the auxiliary power storage device 22 is predicted, a power failure in the auxiliary power storage device 22 may occur in the near future. For this reason, when the vehicle ECU 11 is notified that an abnormality in the auxiliary power storage device 22 is predicted, the vehicle ECU 11 prepares so that the backup power storage device 23 can start backup in a short time when a power failure occurs in the auxiliary power storage device 22. This preparation is similar to that in the first embodiment, and therefore a description thereof will be omitted.

[0098] As in the first embodiment, when the vehicle ECU 11 is notified that an abnormality is predicted in the power storage device 22 for auxiliary machinery, the vehicle ECU 11 charges the power storage device 23 for backup. When the abnormality is no longer predicted, the auxiliary power 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 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 lower the SOC.

[0099] According to the control method of the second embodiment, when an abnormality in the auxiliary power storage device 22 is predicted, the backup power storage device 23 is prepared to start backup in a short time when a power failure occurs in the auxiliary power storage device 22. Therefore, backup can be started in a short time when a power failure occurs in the auxiliary power storage device 22, compared to when backup preparation is made after a power failure occurs in the auxiliary power storage device 22. Therefore, safety is improved when a power failure occurs in the auxiliary power storage device 22.

[0100] 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, thereby increasing the possibility that sufficient power can be supplied to the auxiliary devices 26 when backup is needed.

[0101] According to the control method of the second embodiment, when an abnormality in the auxiliary power storage device 22 is no longer predicted, the preparation state is cancelled, so that the power consumption of the backup power storage device 23 can be suppressed.

[0102] 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, so that deterioration of the backup storage device 23 can be suppressed.

[0103] <Embodiment 3> The third embodiment will be described with reference to Fig. 6. The third embodiment is a modification of the first embodiment or the 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.

[0104] When the management unit 38 of the backup power storage device 23 according to the third embodiment does not back up the auxiliary power storage device 22, the management unit 38 transitions to a low-frequency mode (one example of a power saving mode) having a lower operating clock than the normal mode, rather than to a sleep mode. Since the operating clock is low 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.

[0105] 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 interrupting device 40. Since the first current interrupting device 39 of the backup power storage device 23 is already energized, the backup starts immediately when the second current interrupting device 40 is energized.

[0106] According to the control method of embodiment 3, when it is determined that the driving conditions require preparation for a power failure of the auxiliary storage device 22, the first current interruption device 39 is turned on, so that backup can be started in a shorter time than when the first current interruption device 39 is turned on after a power failure of the auxiliary storage device 22 occurs.

[0107] According to the control method of the third embodiment, when a power failure occurs, the second current interruption device 40 is brought into a conducting state, so that the auxiliary power storage device 22 can be backed up by the backup power storage device 23.

[0108] <Embodiment 4> The fourth embodiment will be described with reference to Fig. 7. The fourth embodiment is a modification of the first to third embodiments. Here, it 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 section) for heating the battery cell 30A therein. Electric power supplied to the heater 41 is supplied by the battery cell 30A.

[0109] 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.

[0110] If a power failure occurs in the auxiliary power storage device 22 thereafter, the vehicle ECU 11 instructs the management unit 38 of the backup power storage device 23 to perform backup. Since 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 is immediately started when the first current interrupt device 39 is switched to a conducting state.

[0111] According to the control method of embodiment 4, when it is determined that the driving conditions are such that preparation for a power failure of the auxiliary power storage device 22 is necessary, the battery cell 30A is heated, so that backup at the rated voltage can be started in a short time when a power failure of the auxiliary power storage device 22 occurs.

[0112] <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 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.

[0113] 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 the 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.

[0114] When a power failure occurs in the auxiliary power storage device 22 thereafter, 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 an energized state. This starts the backup. Since 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 a backup, the backup instruction is received by the management unit 38 of the backup power storage device 23 in a short time. Therefore, when a power failure occurs in the auxiliary power storage device 22, the backup power storage device 23 can start the backup in a short time.

[0115] 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 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, so that it is possible to reduce the time until the management unit 38 of the backup power storage device 23 receives a backup instruction when a power failure occurs in the auxiliary power storage device 22. Therefore, it is possible to start the backup in a short time when a power failure occurs in the auxiliary power storage device 22.

[0116] <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 instructed to discharge, the management unit 38 of the backup power storage device 23 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 an interrupted state.

[0117] 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.

[0118] <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.

[0119] (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.

[0120] (2) In the above embodiment, the vehicle 1 is an autonomous vehicle. However, the vehicle 1 may be a manually driven vehicle.

[0121] (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 driving condition in an urban area and a driving condition on a road with people on the sidewalk, or a driving condition at night and a driving condition 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 driving condition in which the vehicle speed is equal to or higher than a predetermined value (e.g., 80 km / h).

[0122] (4) In the above embodiment, the current driving situation is described as an example of the driving situation of the vehicle 1, but the driving situation of the vehicle 1 may be a driving situation in the near future. For example, when the vehicle 1 enters an urban area in the near future on the set driving route, the driving situation in the near future of the vehicle 1 is a driving situation in which a power failure of the auxiliary power storage device 22 should be prepared. For this reason, a backup may be prepared before entering the urban area. Alternatively, when 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.

[0123] (5) In the above-described second embodiment, a case has been exemplified in which a backup is prepared when an abnormality is predicted in the auxiliary power storage device 22. In contrast, even if an abnormality is predicted in the auxiliary power storage device 22, a backup may not be prepared when the vehicle 1 is not running. In other words, a backup may be prepared when an abnormality is predicted in the auxiliary power storage device 22 and the vehicle 1 is running.

[0124] (6) In the above-described second embodiment, the abnormality of the auxiliary power storage device 22 is described by taking as examples an abnormality of the SOC (overcharging, overdischarging), an abnormality of the voltage, an abnormality of the temperature, and the like, but the abnormality of the auxiliary power storage device 22 is not limited to these. For example, the abnormality may be an abnormality of the SOH (State Of Health) indicating the health state or deterioration state of the auxiliary power storage device 22.

[0125] (7) In the above-described second embodiment, 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 the abnormality is predicted. In contrast, the management unit 38 of the auxiliary power storage device 22 may transmit a start 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. When the start signal is transmitted to the management unit 38 of the backup power storage device 23, the management unit 38 of the backup power storage device 23 is started, so that a backup is prepared. The 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 directly communicate with each other.

[0126] (8) In the above embodiment 2, an example has been described in which the management unit 38 of the auxiliary power storage device 22 predicts an abnormality in the auxiliary power storage device 22. However, information (such as a current value) for predicting an abnormality in the auxiliary power storage device 22 may be transmitted to the vehicle ECU 11, and the vehicle ECU 11 may predict an abnormality in the auxiliary power storage device 22.

[0127] (9) In the fourth embodiment described above, 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.

[0128] (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.

[0129] (11) In the 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.

[0130] (12) In the above embodiment, a part or all of the processes executed by the vehicle ECU 11 may be executed by the management unit 38 of the backup power storage device 23 .

[0131] (13) In the above embodiment, the auxiliary power storage device 22 and the backup power storage device 23 are both rated at 12V. However, the ratings of the auxiliary power storage device 22 and the backup power storage device 23 are not limited thereto. For example, the auxiliary power storage device 22 may be rated at 24V and the backup power storage device 23 may be rated at 12V. The auxiliary power storage device 22 may be rated at 48V and the backup power storage device 23 may be rated at 12V. The auxiliary power storage device 22 may be rated at 48V and the backup power storage device 23 may be rated at 24V. The auxiliary power storage device 22 may be rated at 48V and the backup power storage device 23 may be rated at 48V. When the rated voltage of the backup power storage device 23 is lower than the rated voltage of the auxiliary power storage device 22, the voltage is converted by a DC / DC converter.

[0132] (14) In the above embodiment, a lithium ion secondary battery is used as an example of the power storage element. However, the power storage element may be a capacitor that involves an electrochemical reaction. [Explanation of symbols]

[0133] 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 unit, a control unit) 39 First current interruption device 40 Second current interrupter 41 Heater (an example of a heating unit)

Claims

1. 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 in which 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:

2. A method for controlling a backup power storage device according to claim 1, comprising the steps of: 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.

3. 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.

4. 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.

5. A method for controlling the backup power storage device according to claim 4, comprising: 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.

6. 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.

7. 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.

8. 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.

9. 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 those in which preparation for a power fail is required.

10. 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.

11. 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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