Battery control device, vehicle, battery control method, and non-transitory computer-readable recording medium

Abstract

The present disclosure provides a battery control device, a vehicle, a battery control method, and a non-transitory computer-readable recording medium. The battery control device calculates the outputtable power of a second battery that can replace a first battery supplying power to an onboard device of a vehicle, measures the temperature of the second battery, and determines whether the second battery should replace the first battery using different methods depending on whether the measured temperature is above a preset temperature.

Description

Technical Field

[0001] The present disclosure relates to a battery control device, a vehicle, a battery control method, and a non-transitory computer-readable recording medium. Background Art

[0002] Japanese Patent Gazette No. 2020-156228 discloses a battery control device for a vehicle, which determines the minimum temperature at which the auxiliary battery can ensure the power required for backup of the main battery based on the temperature, charge level (State of Charge: SOC) and calculated output power of the auxiliary battery, thereby determining whether backup is possible. Summary of the Invention

[0003] Problems to be solved by the invention

[0004] In Japanese Patent Application Laid-Open No. 2020-156228, the available output power is estimated based on the battery's resistance. However, batteries tend to experience a significant increase in resistance when temperatures drop from normal to low. Therefore, when determining backup availability based on the estimated available output power, the difference between the available output power and the battery's minimum guaranteed power is more likely to occur at low temperatures, making the determination more accurate. On the other hand, the difference between the available output power and the battery's minimum guaranteed power is less likely to occur at high temperatures, potentially leading to erroneous determinations.

[0005] The present disclosure aims to provide a battery control device, a vehicle, and a battery control method that can ensure accuracy in determining whether another battery can be used for backup based on the power that can be output by the battery, regardless of temperature changes.

[0006] Means for solving problems

[0007] A battery control device according to a first aspect of the present disclosure includes: a memory; and a processor connected to the memory, the processor being configured to calculate outputtable power from a second battery capable of supplying power to on-board equipment of a vehicle in place of a first battery, measure the temperature of the second battery, and determine whether the second battery is to replace the first battery using different methods depending on whether the measured temperature is equal to or higher than a preset set temperature.

[0008] The battery control device of the first embodiment calculates the output power that can be output by the second battery. The second battery is a battery that can replace the first battery to supply power to the vehicle's onboard equipment. Furthermore, the battery control device determines whether the second battery is to replace the first battery. The battery control device makes this determination using different methods depending on whether the measured temperature is above a preset set temperature. By changing the determination method based on the preset set temperature, the battery control device ensures accuracy in determining whether backup for other batteries can be performed based on the output power of the battery, regardless of temperature fluctuations.

[0009] In the battery control device of the second embodiment of the present disclosure, the processor is configured to set the required power required by the vehicle as a threshold value, and when the measured temperature is higher than the set temperature and the outputtable power is higher than the threshold value, determine that the second battery replaces the first battery.

[0010] The battery control device of the second embodiment sets the required power of the vehicle as a threshold value. When the measured temperature is above the set temperature and the available output power is higher than the threshold value, the device determines that the second battery is replacing the first battery. This battery control device ensures accuracy in high-temperature determinations by making a determination based on a threshold value appropriate for actual usage environments when the battery temperature is above the set temperature.

[0011] In the battery control device according to the third aspect of the present disclosure, the processor is configured to add power that takes into account an error of the sensor to the threshold value.

[0012] According to the battery control device of the third aspect, by adding the power that takes into account the sensor error to the threshold value, the determination condition is tightened, thereby ensuring accuracy in determining that the second battery is replacing the first battery.

[0013] In the battery control device according to the fourth aspect of the present disclosure, the processor is configured to add electric power that takes into account changes in ambient temperature to the threshold value.

[0014] According to the battery control device of the fourth aspect, by adding electric power that takes into account changes in ambient temperature to the threshold value, the determination condition is tightened, thereby ensuring accuracy in determining whether the second battery replaces the first battery.

[0015] In the battery control device according to the fifth aspect of the present disclosure, the processor is configured to add electric power that takes into account a fluctuation range of a charge amount to the threshold value.

[0016] According to the battery control device of the fifth aspect, the determination condition is tightened by adding the electric power in consideration of the variation range of the charge amount to the threshold value, thereby ensuring accuracy in determining whether the second battery replaces the first battery.

[0017] In the battery control device of the sixth aspect of the present disclosure, the memory stores a correspondence between the temperature of the second battery and the minimum guaranteed power guaranteed by the second battery, and the processor is configured to determine that the second battery is to replace the first battery when the measured temperature is lower than the set temperature and the output power is higher than the guaranteed power at the evaluation temperature.

[0018] A battery control device according to a sixth aspect determines that the second battery is replacing the first battery when the measured temperature is lower than a set temperature and the output power at the evaluation temperature is higher than the guaranteed power. This battery control device makes this determination based on the guaranteed power corresponding to the battery temperature when the battery temperature is lower than the set temperature, thereby ensuring accuracy in the determination at low temperatures.

[0019] In the battery control device of the seventh aspect of the present disclosure, the processor is configured to set the evaluation temperature when the outputtable power is higher than the guaranteed power as the temperature increase start temperature when the outside air temperature drops when the evaluation temperature is increased and the determination is repeated.

[0020] The battery control device of the seventh embodiment increases the evaluation temperature, repeatedly performs determinations, and sets the evaluation temperature at which the outputtable power exceeds the guaranteed power as the temperature at which the temperature is increased when the outside temperature drops. This battery control device can set the temperature at which the second battery becomes a substitute for the first battery.

[0021] The eighth aspect of the present disclosure is a vehicle comprising: the battery control device described in any one of the first to seventh aspects; the on-board equipment, which includes equipment for implementing automatic driving; the first battery; and the second battery, wherein the processor is configured to switch the source of power supply to the on-board equipment from the first battery to the second battery when it is determined that the second battery becomes a replacement for the first battery.

[0022] The vehicle of the eighth aspect is configured such that onboard equipment for autonomous driving receives power from either a first battery or a second battery. If the vehicle determines that the second battery has been designated as a replacement for the first battery, the vehicle can switch the power supply source for the onboard equipment from the first battery to the second battery. Therefore, this vehicle can provide redundancy in the power supply of the autonomous vehicle.

[0023] A ninth aspect of the present disclosure is a battery control method, wherein a processor calculates outputtable power from a second battery that can replace a first battery for supplying power to an on-board device of a vehicle to supply power to the on-board device, measures the temperature of the second battery, and determines whether the second battery is to replace the first battery by different methods depending on whether the measured temperature is above a predetermined set temperature.

[0024] A ninth aspect of the battery control method uses a computer to calculate the outputtable power that a second battery can output. The second battery is as described above. Furthermore, in this battery control method, the computer determines whether the second battery should replace the first battery, but this determination is made using a different method depending on whether the measured temperature is above a preset set temperature. This battery control method, by varying the determination method based on the preset set temperature, ensures accuracy in determining whether a battery can serve as a backup for another battery based on its outputtable power, regardless of temperature fluctuations.

[0025] The first to ninth aspects can also be implemented as a non-transitory computer-readable recording medium having the determination program recorded thereon.

[0026] Effects of the Invention

[0027] According to the present disclosure, when determining whether backup for another storage battery is possible based on the power that can be output by the storage battery, the accuracy of the determination can be ensured regardless of temperature changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is an example of a schematic diagram of a vehicle and power supply system.

[0029] Figure 2 This is a block diagram showing an example of the hardware configuration of the control unit.

[0030] Figure 3 This is a block diagram showing an example of the structure of the ROM in the control unit.

[0031] Figure 4This is a block diagram showing an example of the functional configuration of the CPU in the control unit.

[0032] Figure 5 This is a flowchart showing an example of the flow of backup determination processing.

[0033] Figure 6 A diagram for explaining determination based on outputtable power. DETAILED DESCRIPTION

[0034] Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

[0035] (Overall structure)

[0036] Figure 1 FIG. 1 is a diagram showing a schematic configuration of a power supply system 10 including a battery control device according to this embodiment. Figure 1 As shown, a power supply system 10 according to this embodiment is installed in a vehicle 12 capable of switching between manual and automatic driving. This power supply system 10 includes a power supply unit 14, a main battery 16, a sub-battery 18, a control unit 20 serving as a battery control device, primary system equipment 22, secondary system equipment 24, a switching circuit 26, a sensor 32, and a heater 34.

[0037] The power supply unit 14, the main battery 16, and the primary system equipment 22 are electrically connected to the switching circuit 26. In addition, the sub-battery 18 and the secondary system equipment 24 are electrically connected to the switching circuit 26, respectively.

[0038] The power supply unit 14 may be a device capable of outputting predetermined power, such as an AC generator or a DC-DC converter. The power output by the power supply unit 14 is supplied to the main battery 16 and the primary system device 22 , and is also output to the switching circuit 26 .

[0039] Main battery 16 is a rechargeable, dischargeable secondary battery, such as a lead acid battery or a lithium battery. Main battery 16 is an example of a first battery. Main battery 16 stores power output by power supply unit 14 and outputs its stored power to primary system equipment 22 and switching circuit 26.

[0040] The auxiliary battery 18 in this embodiment is a lithium battery. Furthermore, the auxiliary battery 18 is not limited to a lithium battery as long as it is a chargeable and dischargeable secondary battery such as a lead-acid battery. The auxiliary battery 18 is an example of a second battery. The auxiliary battery 18 stores power output from the power supply unit 14 and the main battery 16, and outputs its stored power to the secondary system equipment 24, etc. When the vehicle 12 is operating autonomously, even if the main battery 16 fails, the auxiliary battery 18 replaces the main battery 16 to maintain power supply to the secondary system equipment 24 responsible for autonomous driving. In other words, the auxiliary battery 18 is provided redundantly to provide a backup for the main battery 16.

[0041] The control unit 20 has a function of controlling the switching circuit 26 and a function of controlling the heater 34. The details of the control unit 20 will be described later.

[0042] The primary system device 22 is a known vehicle-mounted device that operates using the power output from the power supply unit 14 and the power stored in the main battery 16 .

[0043] Secondary system devices 24 are known onboard devices that operate using the power output from the power supply unit 14, the power stored in the main battery 16, and the power stored in the sub-battery 18. These secondary system devices 24 include onboard devices required for autonomous driving. Secondary system devices 24 are configured to operate using at least one of the power output from the power supply unit 14 and the power stored in the main battery 16 during manual driving, and also operate using the power stored in the sub-battery 18 during autonomous driving.

[0044] The switching circuit 26 switches the power supply source for the secondary system device 24. The switching circuit 26 includes a switch circuit that switches the power connection destination and a DC-DC converter that converts the voltage of the power supplied from the power supply unit 14 and the main battery 16.

[0045] The sensor 32 is located near the sub-battery 18 and includes multiple sensors for monitoring the status of the sub-battery 18. These sensors 32 include a voltage sensor for measuring the terminal voltage of the sub-battery 18, a current sensor for measuring the current flowing into or out of the sub-battery 18, and a temperature sensor for measuring the temperature of the sub-battery 18. The signals from each of the sensors 32 are acquired by the control unit 20, thereby enabling the control unit 20 to understand the status of the sub-battery 18.

[0046] The heater 34 is provided near the sub-battery 18 and is a device for heating the sub-battery 18. For example, a heat exchanger or the like that utilizes heat generated by the engine is used for the heater 34. The heater 34 is controlled by the control unit 20.

[0047] (Control Department)

[0048] The control unit 20 is exemplified by an automatic driving ECU (Electronic Control Unit), and controls the switching circuit 26 based on vehicle information (ignition on / off state, manual driving / automatic driving state, etc.) acquired from vehicle-mounted devices constituting the secondary system device 24 .

[0049] When the vehicle 12 is in manual driving mode, the control unit 20 supplies the power output by the power supply unit 14 and / or the power stored in the main battery 16 to the secondary system device 24. On the other hand, when the vehicle 12 is in automatic driving mode and the determination unit 230 (described later) determines that the sub-battery 18 is capable of backup, the control unit 20 enables the power stored in the sub-battery 18 to be supplied to the secondary system device 24.

[0050] Furthermore, the control unit 20 controls the state of heating by the heater 34 based on the temperature of the sub-battery 18 obtained from the sensor 32 .

[0051] like Figure 2 As shown, the control unit 20 is configured to include a CPU (Central Processing Unit) 20A, which is an example of a hardware processor; a ROM (Read Only Memory) 20B, a RAM (Random Access Memory) 20C, which corresponds to a memory; an input / output interface (I / F) 20D; and a communication I / F 20E. The CPU 20A, ROM 20B, RAM 20C, I / O I / F 20D, and communication I / F 20E are connected to each other via an internal bus 20F so as to be able to communicate with each other.

[0052] The CPU 20A is a central processing unit that executes various programs or controls various components. Specifically, the CPU 20A reads programs from the ROM 20B and executes the programs using the RAM 20C as a work area.

[0053] ROM 20B as a storage unit stores various programs and various data. Figure 3 As shown, the ROM 20B of this embodiment stores a determination program 100 and determination data 110 .

[0054] The determination program 100 is a program for controlling the control unit 20 .

[0055] The judgment data 110 stores data related to a threshold value for determining whether the sub-battery 18 serves as a backup for the main battery 16, that is, a judgment threshold value. The judgment data 110 includes a judgment map 110A and a judgment parameter 110B. The judgment map 110A is data that defines the correspondence between the temperature of the sub-battery 18 and the minimum guaranteed power of the sub-battery 18 (see Figure 6 This guaranteed power is obtained based on the battery characteristics of the most degraded sub-battery 18 within the guaranteed number of years.

[0056] Furthermore, judgment parameter 110B stores the sum of (1) the required power required by vehicle 12, (2) the power taking into account the error of sensor 32, (3) the power taking into account changes in ambient temperature, and (4) the power taking into account the range of variation in the state of charge (SOC) as a constant value. This constant value is set in accordance with the actual usage environment of vehicle 12. The following supplementary explanation is provided for each power value (1) to (4).

[0057] The "required power required by the vehicle 12" in (1) above refers to the minimum power required for the vehicle 12 to travel, that is, the power required for performing so-called evasive driving, which means driving the vehicle 12 until it stops in a safe place in an emergency during automatic driving.

[0058] The "power that takes into account the errors of the sensor 32" in (2) above refers to, for example, power calculated based on the maximum errors of the voltage sensor and the current sensor. Furthermore, the error of the temperature sensor may be considered in addition to or instead of considering the errors of the voltage sensor and the current sensor.

[0059] The "power that takes into account changes in ambient temperature" in (3) above refers to power calculated based on the change in ambient temperature. Here, the change in ambient temperature refers to the temperature drop that is expected in actual usage environments, based on market information. For example, if the battery is affected by the cabin temperature, the difference between the current temperature and the air conditioner's minimum set temperature represents the temperature drop.

[0060] The "power taking into account the SOC variation range" in (4) above refers to the power calculated based on the SOC range that may exist during control. Here, the SOC variation range refers to the range of the controlled SOC when charging and discharging are performed in the battery system.

[0061] The RAM 20C temporarily stores programs and data as a work area.

[0062] The input / output I / F 20D is an interface for communicating with the switching circuit 26 , the sensor 32 , and the heater 34 .

[0063] The communication I / F 20E is an interface for connecting to other ECUs installed in the vehicle 12. This interface uses, for example, a communication standard based on the CAN protocol. If the determination unit 230, described later, determines that the sub-battery 18 is not providing backup for the main battery 16, the control unit 20 can output an abnormality notification via the communication I / F 20E.

[0064] Furthermore, the control unit 20 may include a memory in addition to or instead of the ROM 20B. The memory may be formed of, for example, a HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0065] like Figure 4 As shown, in the control unit 20 of this embodiment, the CPU 20A functions as the calculation unit 200 , the measurement unit 210 , the threshold setting unit 220 , the determination unit 230 , the temperature setting unit 240 , and the switching unit 250 by executing the determination program 100 .

[0066] Calculation unit 200 has a function of calculating the outputtable power that can be outputted from sub-battery 18. The outputtable power can be calculated, for example, using the method disclosed in Japanese Patent Application Laid-Open No. 2020-156228. Calculation unit 200 in this embodiment calculates the outputtable power based on waveforms during charging and discharging of sub-battery 18.

[0067] The measuring unit 210 has a function of measuring the temperature of the sub-battery 18. Specifically, the measuring unit 210 measures the temperature based on information acquired from the temperature sensor among the sensors 32.

[0068] Threshold setting unit 220 has the function of setting a threshold value for determining whether sub-battery 18 serves as a backup for main battery 16. In this embodiment, the threshold values ​​are set differently based on a preset set temperature. Specifically, when the temperature of sub-battery 18 is below the set temperature, threshold setting unit 220 sets the power value for each temperature specified in determination map 110A as the threshold value. Furthermore, when the temperature of sub-battery 18 is above the set temperature, threshold setting unit 220 sets the fixed value specified in determination parameter 110B as the threshold value. Furthermore, when determination map 110A is set as the threshold value, it is preferable to set the set temperature to a temperature that provides a sufficient difference from the outputtable power.

[0069] Determination unit 230 has a function of determining whether sub-battery 18 is serving as a backup for main battery 16. Determination unit 230 in this embodiment determines that sub-battery 18 is capable of backup when the output power is higher than a determination threshold. As described above, the determination threshold is set based on different data depending on whether the temperature of sub-battery 18 is higher than a set temperature. In other words, determination unit 230 performs a determination using different methods depending on whether the temperature of sub-battery 18 is higher than a set temperature. Furthermore, in the backup determination process described later, when the power value of determination map 110A is set as the determination threshold, determination unit 230 increases the temperature (hereinafter referred to as the "evaluation temperature") on the referenced determination map 110A and repeats the determination.

[0070] Temperature setting unit 240 has the function of setting a temperature at which the temperature rises when the outside air temperature drops. If the temperature of the sub-battery 18 is below the set temperature, and if determination unit 230 increases the evaluation temperature and repeats the determination, temperature setting unit 240 sets the temperature rise start temperature to the evaluation temperature at which the outputtable power exceeds the guaranteed power. Furthermore, if the sub-battery 18 temperature is above the set temperature, temperature setting unit 240 sets the temperature rise start temperature as the temperature obtained by subtracting a predetermined value from the current sub-battery 18 temperature. As mentioned above, this predetermined value is based on market information and is the amount of temperature drop that is expected in actual usage environments. If the battery is affected by the interior temperature, the difference between the current temperature and the air conditioner's minimum set temperature can be used.

[0071] Switching unit 250 has a function of switching the source of power supplied to secondary system device 24 from main battery 16 to sub-battery 18. Switching unit 250 in this embodiment switches the source of power supplied to secondary system device 24 from main battery 16 to sub-battery 18 when determination unit 230 determines that sub-battery 18 is replacing main battery 16.

[0072] (Control process)

[0073] use Figure 5 The following flowchart illustrates the battery control method of this embodiment, specifically, the flow of the backup determination process executed by the control unit 20. The process in the control unit 20 is implemented by causing the CPU 20A to function as the calculation unit 200, measurement unit 210, threshold setting unit 220, determination unit 230, temperature setting unit 240, and switching unit 250 described above.

[0074] exist Figure 5 In step S100, CPU 20A calculates the outputtable power of sub-battery 18. This outputtable power may be not only the outputtable power at the current temperature of sub-battery 18 but also an estimated value of the outputtable power at a predetermined temperature.

[0075] In step S101, the CPU 20A determines whether the temperature of the sub-battery 18 is lower than the set temperature. If the CPU 20A determines that the temperature of the sub-battery 18 is lower than the set temperature (if step S101 returns "YES"), the process proceeds to step S102. On the other hand, if the CPU 20A determines that the temperature of the sub-battery 18 is not lower than the set temperature, that is, if the temperature of the sub-battery 18 is higher than the set temperature (if step S101 returns "NO"), the process proceeds to step S110.

[0076] In step S102 , CPU 20A sets a value of -15 to a variable N. This variable N is referred to as an evaluation temperature in step S104 described later.

[0077] Next, a loop process based on the variable N is executed from step S103 to step S108.

[0078] In step S104, the CPU 20A sets a determination threshold based on the determination map 110A. The CPU 20A refers to the determination map 110A and sets the power value corresponding to the evaluation temperature, that is, the current variable N, as the determination threshold.

[0079] In step S105 , the CPU 20A sets the variable N to the temperature at which the heater 34 starts heating.

[0080] In step S106, the CPU 20A determines whether the output power of the secondary battery 18 exceeds the judgment threshold. The CPU 20A makes this determination by comparing the output power at the evaluation temperature with the power value on the judgment map 110A, which is set as the judgment threshold. If the CPU 20A determines that the output power exceeds the judgment threshold (if step S106 returns yes), the CPU 20A interrupts the loop processing and ends the backup judgment process. On the other hand, if the CPU 20A determines that the output power does not exceed the judgment threshold, that is, that the output power is below the judgment threshold (if step S106 returns no), the process proceeds to step S107.

[0081] In step S107 , the CPU 20A adds 1 to the variable N.

[0082] In step S108, the CPU 20A determines whether the variable N is greater than 0. If the CPU 20A determines that the variable N is greater than 0, the loop processing ends. On the other hand, if the CPU 20A determines that the variable N is not greater than 0, that is, if the variable N is less than 0, the CPU 20A returns to step S103 and continues the loop processing.

[0083] In step S109, CPU 20A issues an abnormality notification. This causes control unit 20, acting as the autonomous driving ECU, to control the vehicle 12 so as not to issue permission to switch from manual to autonomous driving. Furthermore, by transmitting the abnormality notification to other ECUs, such as the meter ECU, the driver of vehicle 12 can be informed that autonomous driving is no longer possible.

[0084] In step S110 , the CPU 20A sets the constant value of the determination parameter 110B as the determination threshold value.

[0085] In step S111 , CPU 20A sets a temperature obtained by subtracting a predetermined value from the current temperature of sub-battery 18 as a temperature increase start temperature.

[0086] In step S112, the CPU 20A determines whether the output power of the sub-battery 18 exceeds the judgment threshold. The CPU 20A makes this determination by comparing the output power at the current temperature of the sub-battery 18 with the constant value of the judgment parameter 110B set as the judgment threshold. If the CPU 20A determines that the output power does not exceed the judgment threshold, i.e., that the output power is below the judgment threshold (no in step S112), the CPU 20A proceeds to step S109. On the other hand, if the CPU 20A determines that the output power exceeds the judgment threshold (yes in step S112), the CPU 20A terminates the backup determination process.

[0087] (Summary of Implementation Methods)

[0088] In control unit 20 of the present embodiment, calculation unit 200 calculates the outputtable power that can be outputted from sub-battery 18 , and determination unit 230 is configured to determine whether sub-battery 18 serves as a backup for main battery 16 .

[0089] Here, through Figure 6 Supplementary explanation is given on the case where the backup is determined based on the calculated output power. Figure 6 In the graph, L0 represents the output power of the battery relative to temperature, and L1 represents the minimum guaranteed power of the battery. Furthermore, L2 represents the total of the required power required by the vehicle 12, the power taking into account errors in the sensor 32, the power taking into account changes in ambient temperature, and the power taking into account the range of variation in the charge level.

[0090] As shown by L0 and L1, the battery's resistance tends to rise significantly when it changes from room temperature (i.e., the temperature under normal usage conditions) to low temperatures. Therefore, the power drops dramatically from room temperature to low temperatures. On the other hand, the power changes more gradually from room temperature to high temperatures. This tendency indicates that when comparing the difference between L0, which represents the output power, and L1, which represents the battery's guaranteed power, the difference D1 at low temperatures is greater than the difference D2 at high temperatures, making it easier to ensure accurate judgment.

[0091] Therefore, in this embodiment, the temperature setting is set to a certain level, indicating the difference between L0, which indicates the outputtable power, and L1, which indicates the guaranteed power of the battery. Determination unit 230 uses different methods to determine whether the temperature of sub-battery 18 is above a predetermined set temperature. Determination unit 230 in this embodiment uses the guaranteed power corresponding to the sub-battery 18 temperature as the determination threshold when the sub-battery 18 temperature is below the set temperature, and performs the determination. This ensures accuracy in low-temperature determinations.

[0092] On the other hand, when the battery is at a high temperature, the difference D2 between L0, indicating the output power, and L1, indicating the guaranteed battery power, is smaller than the difference D1 at a low temperature. Therefore, a judgment method that uses the guaranteed power as the judgment threshold may result in an erroneous judgment. Therefore, when the sub-battery 18 is at a set temperature or above, judgment unit 230 in this embodiment performs a judgment based on a threshold value that matches the actual usage environment. As an example, when the power that matches the actual usage environment is represented as L2, when the battery is at a high temperature, the difference D3 between L0, indicating the output power, and L2, indicating the power that matches the actual usage environment, is greater than the difference D2. This ensures the accuracy of the judgment at high temperatures.

[0093] As described above, according to this embodiment, by changing the determination method based on the preset temperature, when determining whether backup for the main battery 16 is possible based on the power outputtable by the sub-battery 18 , the determination accuracy can be ensured regardless of temperature changes.

[0094] Furthermore, while this embodiment utilizes a threshold value appropriate to the actual usage environment when the temperature of the sub-battery 18 is above a set temperature, this threshold value is the sum of the required power required by the vehicle 12, power accounting for sensor 32 errors, power accounting for ambient temperature fluctuations, and power accounting for the SOC fluctuation range. When determining whether the sub-battery 18 serves as a backup for the main battery 16, at least the required power required by the vehicle 12 may be used as the threshold value. However, in this embodiment, power accounting for sensor 32 errors, power accounting for ambient temperature fluctuations, and power accounting for the SOC fluctuation range are added to the threshold value as a safety margin. This ensures accurate determination of whether the sub-battery 18 serves as a backup for the main battery 16.

[0095] In this embodiment, as Figure 5 As shown in the loop processing from steps S103 to S108, the determination unit 230 increases the variable N corresponding to the evaluation temperature and repeats the determination. Furthermore, the temperature setting unit 240 sets the evaluation temperature (i.e., variable N) at which the outputtable power exceeds the guaranteed power threshold, which serves as the determination threshold, as the temperature increase start temperature when the outside temperature drops (see step S105). Thus, according to this embodiment, the temperature at which the sub-battery 18 serves as a backup for the main battery 16 can be set. Specifically, by controlling the heater 34 so that the temperature of the sub-battery 18 does not fall below the temperature increase start temperature, the sub-battery 18 can be ensured to serve as a backup power source.

[0096] The power supply system 10, including the control unit 20 of this embodiment, is mounted on a vehicle 12. Furthermore, the vehicle 12 is configured so that secondary system devices 24, including onboard devices for autonomous driving, receive power from either the main battery 16 or the sub-battery 18. In the vehicle 12 of this embodiment, the switching unit 250 can switch the power supply source for the secondary system devices 24 from the main battery 16 to the sub-battery 18 when it determines that the sub-battery 18 is serving as a backup for the main battery 16. Therefore, the vehicle 12 of this embodiment can maintain redundancy in the power supply of the autonomous vehicle.

[0097] Exam Preparation

[0098] In addition, in the above-mentioned embodiment, each process executed by CPU20A reading software (program) can also be executed by various processors other than CPU. As the processor in this case, FPGA (Field-Programmable Gate Array) and other PLD (Programmable Logic Device) whose circuit structure can be changed after manufacturing, and ASIC (Application Specific Integrated Circuit) as a dedicated circuit having a processor including a circuit structure specially designed for executing specific processes can be exemplified. In addition, each of the above-mentioned processes can be executed by one of these various processors, or by a combination of two or more processors of the same type or different types (for example, multiple FPGAs, and a combination of a CPU and an FPGA, etc.). In addition, the hardware structure of these various processors can also be a circuit composed of a combination of circuit elements such as semiconductor elements.

[0099] In addition, in the above embodiment, each program is pre-stored (installed) in a non-temporary recording medium that can be read by a computer. For example, the judgment program 100 in the control unit 20 is pre-stored in the ROM 20B. However, it is not limited to this. Each program can also be provided in a non-temporary recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), and a USB (Universal Serial Bus) memory. In addition, the program can also be downloaded from an external device via a network.

[0100] The processing flow described in the above embodiment is merely an example, and unnecessary steps may be deleted, new steps may be added, or the processing order may be changed without departing from the gist of the invention.

Claims

1. A battery control device comprising: Memory; a processor connected to the memory, The memory stores a correspondence between a temperature of a second battery capable of supplying power to the vehicle-mounted device in place of the first battery and a minimum guaranteed power guaranteed by the second battery. The processor is configured to: The outputtable power of the second storage battery is calculated, and measuring the temperature of the second battery, and Whether the second storage battery will replace the first storage battery is determined by different methods depending on whether the measured temperature is above a preset temperature. When the measured temperature is higher than the set temperature, a first determination threshold value, which is a fixed value, is compared with the outputtable power, and when the outputtable power is higher than the first determination threshold value, it is determined that the second storage battery is replacing the first storage battery. If the measured temperature is lower than the set temperature, the measured temperature is set as the evaluation temperature, and a second judgment threshold corresponding to the evaluation temperature is compared with the outputtable power. If it is determined that the outputtable power is below the second judgment threshold, the evaluation temperature is increased, and the comparison between the second judgment threshold and the outputtable power is repeated until the outputtable power exceeds the second judgment threshold. If the outputtable power exceeds the second judgment threshold, it is determined that the second storage battery has become a replacement for the first storage battery. The first judgment threshold is the minimum electric power required for the vehicle to travel. The second determination threshold is the guaranteed power.

2. The battery control device according to claim 1, wherein: The processor is configured to add power that takes into account an error of the sensor to the first determination threshold.

3. The battery control device according to claim 1 or 2, wherein: The processor is configured to add electric power in consideration of a change in ambient temperature to the first determination threshold.

4. The battery control device according to claim 1 or 2, wherein: The processor is configured to add electric power in consideration of a variation range of a charge amount to the first determination threshold.

5. The battery control device according to claim 1, wherein: The processor is configured to set the evaluation temperature when the outputtable power is higher than the guaranteed power as a temperature increase start temperature when the outside air temperature decreases, when the evaluation temperature is increased and determination is repeated.

6. A vehicle comprising: The battery control device according to any one of claims 1 to 5; The vehicle-mounted equipment includes equipment for implementing autonomous driving; the first storage battery; the second battery, The processor is configured to: When it is determined that the second battery replaces the first battery, the source of power supplied to the in-vehicle device is switched from the first battery to the second battery.

7. A battery control method, wherein: Through the processor, The outputtable power that can be outputted from the second storage battery that can supply power to the onboard equipment of the vehicle instead of the first storage battery that supplies power to the onboard equipment of the vehicle is calculated, and The temperature of the second battery is measured, and whether the second battery is to be used as a replacement for the first battery is determined by different methods depending on whether the measured temperature is above a preset temperature. When the measured temperature is higher than the set temperature, a first determination threshold value, i.e., a fixed value, which is the minimum power required for traveling the vehicle, is compared with the outputtable power. When the outputtable power is higher than the first determination threshold value, it is determined that the second battery is replacing the first battery. When the measured temperature is lower than the set temperature, based on the correspondence between the temperature of the second battery and a second judgment threshold, i.e., the minimum guaranteed power guaranteed by the second battery, the measured temperature is set as an evaluation temperature and the second judgment threshold corresponding to the evaluation temperature is compared with the outputtable power. When it is determined that the outputtable power is below the second judgment threshold, the evaluation temperature is increased and the comparison between the second judgment threshold and the outputtable power is repeated until the outputtable power is higher than the guaranteed power. When the outputtable power is higher than the guaranteed power, it is determined that the second battery has become a replacement for the first battery.

8. A non-transitory computer-readable recording medium having a judgment program recorded thereon, the judgment program causing a computer to execute the following processing, namely, The outputtable power that can be outputted from the second storage battery that can supply power to the onboard equipment of the vehicle instead of the first storage battery that supplies power to the onboard equipment of the vehicle is calculated, and measuring the temperature of the second battery, and Whether the second storage battery will replace the first storage battery is determined by different methods depending on whether the measured temperature is above a preset temperature. When the measured temperature is higher than the set temperature, a first determination threshold value, i.e., a fixed value, which is the minimum power required for traveling the vehicle, is compared with the outputtable power. When the outputtable power is higher than the first determination threshold value, it is determined that the second battery is replacing the first battery. When the measured temperature is lower than the set temperature, based on the correspondence between the temperature of the second battery and a second judgment threshold, i.e., the minimum guaranteed power guaranteed by the second battery, the measured temperature is set as an evaluation temperature and the second judgment threshold corresponding to the evaluation temperature is compared with the outputtable power. When it is determined that the outputtable power is below the second judgment threshold, the evaluation temperature is increased and the comparison between the second judgment threshold and the outputtable power is repeated until the outputtable power is higher than the guaranteed power. When the outputtable power is higher than the guaranteed power, it is determined that the second battery has become a replacement for the first battery.

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