Fully Charged Capacity Measuring Device

Abstract

To provide a full charge capacity measuring device capable of measuring the full charge capacity of a sub-battery while holding a storage rate necessary for backup power supply of a system.SOLUTION: A full charge capacity measuring device for measuring a full charge capacity of a sub-battery provided for backup of a main battery for supplying power to an automatic operation system, comprises: an acquisition unit for acquiring a temperature of the sub-battery; a determination unit for determining whether or not the current temperature of the sub-battery is less than a lower limit temperature at which the automatic operation system can operate; and a measurement control unit for performing measurement control of the full charge capacity of the sub-battery when the current temperature is less than the lower limit temperature.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an apparatus for measuring the full charge capacity of a battery.

Background Art

[0002] Patent Document 1 discloses a full charge capacity calculation device that calculates the full charge capacity of a battery based on the charge and discharge amount of the battery during one trip from when the start switch of a vehicle is turned on until it is turned off.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A sub-battery provided for backup of the main battery needs to always maintain a high state of charge (SOC) in case of a failure of the main battery. For this reason, a method of measuring the full charge capacity by once discharging the state of charge to a predetermined low state of charge (low SOC) and then recharging until it reaches a predetermined high state of charge (high SOC) cannot be easily applied to the sub-battery.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a full charge capacity measurement device capable of measuring the full charge capacity of a sub-battery while maintaining the state of charge necessary for backup power supply of the system.

Means for Solving the Problems

[0006] In order to solve the above problems, one aspect of the disclosed technology is a fully charged capacity measuring device that measures the fully charged capacity of a sub-battery provided for backup of a main battery that supplies power to an autonomous driving system, the fully charged capacity measuring device including: an acquisition unit that acquires the temperature of the sub-battery; a determination unit that determines whether the current temperature of the sub-battery is lower than the lower limit temperature at which the autonomous driving system can operate; and a measurement control unit that performs measurement control of the fully charged capacity of the sub-battery when the current temperature is lower than the lower limit temperature.

Effect of the Invention

[0007] According to the fully charged capacity measuring device of the present disclosure, since the measurement control of the fully charged capacity of the sub-battery is performed only when the temperature of the battery when the autonomous driving system does not operate is low, it is possible to measure the fully charged capacity of the sub-battery while maintaining the power storage rate required for backup power supply of systems other than the autonomous driving system.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Mode for Carrying Out the Invention

[0009] The fully charged capacity measuring device of the present disclosure performs measurement control of the fully charged capacity of the sub-battery at a low temperature of the sub-battery when the autonomous driving system does not operate and backup power supply to the autonomous driving system does not occur. Thereby, it is possible to achieve both maintaining the power storage rate required for backup power supply of the system and measuring the fully charged capacity of the sub-battery. Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0010] <Embodiment> [Configuration] FIG. 1 is a functional block diagram of a power supply system 10 including a full charge capacity measurement device 500 according to an embodiment of the present disclosure and its peripheral parts. The power supply system 10 illustrated in FIG. 1 includes a main battery 100, a DCDC converter 200, a sub-battery 300, and a full charge capacity measurement device 500. In FIG. 1, connection lines through which power flows are shown as solid lines, and connection lines through which detection signals, control signals, etc. flow are shown as dotted lines.

[0011] The power supply system 10 shown in FIG. 1 is mounted on a vehicle equipped with an automatic driving system or the like. In the following embodiments, the case where the power supply system 10 is mounted on a vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a battery electric vehicle (BEV) that uses an electric motor as a power source will be taken as an example to explain the control of the full charge capacity measurement device 500 according to the present embodiment.

[0012] The main battery 100 is a secondary battery configured to be chargeable and dischargeable, and is, for example, a lead storage battery. The main battery 100 is connected to the DCDC converter 200, and supplies the power stored in itself to the sub-battery 300, the first in-vehicle load 410, and the second in-vehicle load 420 via the DCDC converter 200. This main battery 100 functions as a main battery that supplies power to the first in-vehicle load 410 and the second in-vehicle load 420 during normal times when no abnormality such as a power supply failure occurs.

[0013] The DCDC converter 200 is a power converter that connects the main battery 100 to the sub - battery 300, the first in - vehicle load 410, and the second in - vehicle load 420, and supplies the power of the main battery 100 to the sub - battery 300, the first in - vehicle load 410, and the second in - vehicle load 420. When supplying power, the DCDC converter 200 can convert the voltage of the main battery 100, which is the input voltage, to a predetermined voltage and output it.

[0014] The sub - battery 300 is a secondary battery configured to be chargeable and dischargeable, for example, a lithium iron phosphate - based lithium - ion battery (LFP battery). The sub - battery 300 is connected to the DCDC converter 200, the first in - vehicle load 410, and the second in - vehicle load 420, and supplies the power it stores to the first in - vehicle load 410 and the second in - vehicle load 420, or charges the power output from the main battery 100 via the DCDC converter 200. This sub - battery 300 functions as a backup battery that supplies power to the first in - vehicle load 410 and the second in - vehicle load 420 in an emergency such as when the main battery 100 fails.

[0015] The first in - vehicle load 410 and the second in - vehicle load 420 are configured as electronic control units (ECUs: Electronic Control Unit) or systems mounted on the vehicle. The first in - vehicle load 410 in this embodiment is a load that requires a redundant power supply only when the vehicle is executing autonomous driving. Examples of this first in - vehicle load 410 include ECUs and systems such as electric power steering (EPS) and advanced driver assistance systems (ADAS). The second in - vehicle load 420 in this embodiment is a load that requires a redundant power supply not only when the vehicle is executing autonomous driving but also when manual driving is being performed by the driver. Examples of this second in - vehicle load 420 include ECUs and systems such as shift - by - wire (SBW) and electric brake (EBK). Note that the vehicle may be equipped with not only the first in - vehicle load 410 and the second in - vehicle load 420 illustrated in FIG. 1 but also loads that do not require a redundant power supply.

[0016] The full charge capacity measurement device 500 is configured to measure the full charge capacity of the sub - battery 300. This full charge capacity measurement device 500 includes an acquisition unit 510, a determination unit 520, a calculation unit 530, and a measurement control unit 540.

[0017] The acquisition unit 510 acquires the temperature of the sub - battery 300. The temperature of the sub - battery 300 can be acquired via a detection element (not shown) such as a temperature sensor provided in the sub - battery 300.

[0018] The determination unit 520 compares the current temperature of the sub - battery 300 acquired by the acquisition unit 510 with the lower limit temperature at which the automatic driving system mounted on the vehicle can operate, and determines whether the current temperature is lower than the lower limit temperature. This lower limit temperature is the minimum temperature required for the sub - battery 300 when the automatic driving system executes the automatic driving function and is defined in advance.

[0019] The calculation unit 530 calculates various values related to the sub - battery 300. Specifically, the calculation unit 530 calculates the temperature difference between the current temperature of the sub - battery 300 and the lower limit temperature at which the automatic driving system can operate. Also, the calculation unit 530 calculates the charge - discharge value that the sub - battery 300 can output at the current temperature based on the current temperature of the sub - battery 300. Further, the calculation unit 530 calculates the time (estimated value) required until the completion of the full charge capacity measurement process of the sub - battery 300 by the measurement control unit 540 based on the charge - discharge value that the sub - battery 300 can output at the current temperature. Also, the calculation unit 530 calculates the time (estimated value) required for the temperature of the sub - battery 300 to rise to the lower limit temperature at which the automatic driving system can operate based on the temperature difference between the current temperature of the sub - battery 300 and the lower limit temperature at which the automatic driving system can operate and the charge - discharge value that the sub - battery 300 can output at the current temperature.

[0020] The measurement control unit 540 is configured to control the full charge capacity measurement process of the sub-battery 300. If the current temperature of the sub-battery 300 is a low temperature at which the automatic driving system does not operate, the measurement control unit 540 performs the measurement of the full charge capacity of the sub-battery 300. For the measurement of the full charge capacity of the sub-battery 300, well-known techniques can be used, such as measuring or estimating based on information obtained by discharging the state of charge to a predetermined low SOC once and then recharging until reaching a predetermined high SOC.

[0021] Note that part or all of the full charge capacity measurement device 500 described above can typically be configured as an electronic control unit including a processor, a memory, an input / output interface, and the like. The electronic control unit realizes all or some of the functions performed by the acquisition unit 510, the determination unit 520, the calculation unit 530, and the measurement control unit 540 by the processor reading and executing the program stored in the memory.

[0022] [Control] Next, with further reference to FIGS. 2A, 2B, and 2C, the control performed by the full charge capacity measurement device 500 according to an embodiment of the present disclosure will be described. FIGS. 2A, 2B, and 2C are flowcharts showing the processing procedures of the full charge capacity measurement control of the sub-battery 300 executed by the full charge capacity measurement device 500. The process of FIG. 2A, the process of FIG. 2B, and the process of FIG. 2C are respectively connected by connectors X, Y, and Z. The full charge capacity measurement control of the sub-battery 300 is started, for example, when the full charge capacity measurement device 500 is requested to measure the full charge capacity of the sub-battery 300.

[0023] (Step S201) The determination unit 520 of the full charge capacity measurement device 500 determines whether the current temperature T1 [°C] of the sub-battery 300 acquired by the acquisition unit 510 is lower than a predetermined lower limit temperature T2 [°C] at which the automatic driving system can operate. By this determination, it is possible to grasp whether it is necessary for the sub-battery 300 to prepare backup power for automatic driving.

[0024] When the determination unit 520 determines that the current temperature T1 is less than the lower limit temperature T2 (T1 < T2) (step S201, yes), the process proceeds to step S202. On the other hand, when the determination unit 520 determines that the current temperature T1 is greater than or equal to the lower limit temperature T2 (T1 ≥ T2) (step S201, no), since the state of charge of the sub-battery 300 cannot be decreased, the full charge capacity measurement control of the present sub-battery 300 ends.

[0025] (Step S202) The calculation unit 530 of the full charge capacity measurement device 500 calculates the temperature difference ΔT [°C], which is the difference between the current temperature T1 of the sub-battery 300 and the lower limit temperature T2 at which the automatic driving system can operate (ΔT = T2 - T1). When the temperature difference ΔT between the current temperature T1 and the lower limit temperature T2 is calculated by the calculation unit 530, the process proceeds to step S203.

[0026] (Step S203) The calculation unit 530 of the full charge capacity measurement device 500 calculates the charge and discharge value that the sub-battery 300 at the current temperature T1 can output. The charge and discharge value that this sub-battery 300 can output is the sum of the discharge value, which is the power output from the sub-battery 300 to the main battery 100 via the DCDC converter 200 (which may include the power output from the sub-battery 300 to the first vehicle-mounted load 410 and the second vehicle-mounted load 420), and the charge value, which is the power input to the sub-battery 300 from the main battery 100 via the DCDC converter 200. When the charge and discharge value that the sub-battery 300 at the current temperature T1 can output is calculated by the calculation unit 530, the process proceeds to step S204.

[0027] (Step S204) The calculation unit 530 of the full charge capacity measurement device 500 calculates a first estimated time t1 [seconds], which is the time estimated to be required until the measurement process of the full charge capacity of the sub-battery 300 is completed, based on the charge and discharge values that the sub-battery 300 at the current temperature T1 can output. This first estimated time t1 includes at least the time for discharging the sub-battery 300 from the current state of charge (current SOC) to a predetermined low state of charge (low SOC) at the calculated discharge value, and the time for charging the sub-battery 300 from the low SOC to a predetermined high state of charge (high SOC) at the calculated charge value. When the first estimated time t1 until the measurement process of the full charge capacity of the sub-battery 300 is completed is calculated by the calculation unit 530, the process proceeds to step S205.

[0028] (Step S205) The calculation unit 530 of the full charge capacity measurement device 500 calculates a second estimated time t2 [seconds], which is the time estimated to be required for the temperature of the sub-battery 300 to rise from the current temperature T1 to the lower limit temperature T2 due to the heat generation of the sub-battery 300 accompanying the measurement process of the full charge capacity of the sub-battery 300. When the second estimated time t2 until the temperature of the sub-battery 300 rises from the current temperature T1 to the lower limit temperature T2 is calculated by the calculation unit 530, the process proceeds to step S206.

[0029] (Step S206) The measurement control unit 540 of the full charge capacity measurement device 500 determines whether the first estimated time t1 until the measurement process of the full charge capacity of the sub-battery 300 calculated by the calculation unit 530 is shorter than the second estimated time t2 required for the temperature of the sub-battery 300 to rise from the current temperature T1 to the lower limit temperature T2. By this determination, it is possible to grasp whether there is a possibility that the automatic operation will operate during the full charge capacity measurement process.

[0030] When the measurement control unit 540 determines that the first estimated time t1 is shorter than the second estimated time t2 (t1 < t2) (step S206, yes), the process proceeds to step S207. On the other hand, when the measurement control unit 540 determines that the first estimated time t1 is longer than the second estimated time t2 (t1 ≧ t2) (step S206, no), since the charge storage rate of the sub-battery 300 cannot be decreased, the measurement control of the full charge capacity of this sub-battery 300 ends.

[0031] (Step S207) The measurement control unit 540 of the full charge capacity measurement device 500 starts a discharge process of discharging the power of the sub-battery 300 to decrease the charge storage rate. This discharge process is preferably carried out by transferring power from the sub-battery 300 to the main battery 100. When the discharge process of the sub-battery 300 is started by the measurement control unit 540, the process proceeds to step S208.

[0032] (Step S208) The measurement control unit 540 of the full charge capacity measurement device 500 determines again whether the first estimated time t1 until the measurement process of the full charge capacity of the sub-battery 300 is completed is shorter than the second estimated time t2 required for the temperature of the sub-battery 300 to rise from the current temperature T1 to the lower limit temperature T2.

[0033] When the measurement control unit 540 determines that the first estimated time t1 is shorter than the second estimated time t2 (t1 < t2) (step S208, yes), the process proceeds to step S209. On the other hand, when the measurement control unit 540 determines that the first estimated time t1 is longer than the second estimated time t2 (t1 ≧ t2) (step S208, no), the process proceeds to step S213.

[0034] (Step S209) The measurement control unit 540 of the full charge capacity measurement device 500 determines whether the charge storage rate of the sub-battery 300 has decreased to a predetermined low charge storage rate (low SOC). This low SOC can be determined in advance according to the performance and capacity of the sub-battery 300, etc.

[0035] When the measurement control unit 540 determines that the state of charge of the sub - battery 300 has decreased to a low state of charge (step S209, yes), the process proceeds to step S210. On the other hand, when the measurement control unit 540 determines that the state of charge of the sub - battery 300 has not yet decreased to a low state of charge (step S209, no), the process proceeds to step S208.

[0036] (Step S210) The measurement control unit 540 of the full - charge capacity measurement device 500 ends the discharge process of discharging the power of the sub - battery 300 to reduce the state of charge, and starts a charging process of supplying power to the sub - battery 300 to increase the state of charge. This charging process is typically implemented by power transfer from the main battery 100 to the sub - battery 300. When the discharge process of the sub - battery 300 is ended by the measurement control unit 540 and the charging process of the sub - battery 300 is started, the process proceeds to step S211.

[0037] (Step S211) The measurement control unit 540 of the full - charge capacity measurement device 500 determines again whether the first estimated time t1 until the measurement process of the full - charge capacity of the sub - battery 300 is completed is shorter than the second estimated time t2 required for the temperature of the sub - battery 300 to rise from the current temperature T1 to the lower - limit temperature T2.

[0038] When the measurement control unit 540 determines that the first estimated time t1 is shorter than the second estimated time t2 (t1 < t2) (step S211, yes), the process proceeds to step S212. On the other hand, when the measurement control unit 540 determines that the first estimated time t1 is longer than the second estimated time t2 (t1 ≧ t2) (step S211, no), the process proceeds to step S213.

[0039] (Step S212) The measurement control unit 540 of the full - charge capacity measurement device 500 determines whether the state of charge of the sub - battery 300 has increased to a predetermined high state of charge (high SOC). This high SOC can be determined in advance according to the performance and capacity of the sub - battery 300, etc.

[0040] When the measurement control unit 540 determines that the state of charge of the sub-battery 300 has increased to a high state of charge (step S212, yes), the process proceeds to step S213. On the other hand, when the measurement control unit 540 determines that the state of charge of the sub-battery 300 has not yet increased to a high state of charge (step S212, no), the process proceeds to step S211.

[0041] (Step S213) The measurement control unit 540 of the full charge capacity measurement device 500 stops the discharging process or the charging process of the sub-battery 300 that is in progress. Thereby, the measurement control of the full charge capacity of this sub-battery 300 ends.

[0042] (Step S214) The measurement control unit 540 of the full charge capacity measurement device 500 ends the charging process of supplying power to the sub-battery 300 to increase the state of charge. When the charging process of the sub-battery 300 is ended by the measurement control unit 540, the process proceeds to step S215.

[0043] (Step S215) The measurement control unit 540 of the full charge capacity measurement device 500 calculates the full charge capacity of the sub-battery 300 based on the data obtained by the discharging process and the charging process of the sub-battery 300. Specifically, the full charge capacity FCC [Ah] of the sub-battery 300 can be derived by the following formula based on the state of charge SOC_V1 [%] calculated from the open circuit voltage V1 and the state of charge SOC_V2 [%] calculated from the open circuit voltage V2 when charging with a charge amount C [Ah] is performed between the open circuit voltage V1 and the open circuit voltage V2 (V1 < V2). When the full charge capacity of the sub-battery 300 is calculated by the measurement control unit 540, the process proceeds to step S216. FCC = C × 100 / (SOC_V2 - SOC_V1)

[0044] (Step S216) The determination unit 520 of the fully charged capacity measurement device 500 determines whether the current temperature T1 of the sub-battery 300 is equal to or higher than the lower limit temperature T2 at which the automatic driving system can operate. Through this determination, it is possible to ascertain whether the sub-battery 300 can prepare backup power for automatic driving.

[0045] If the determination unit 520 determines that the current temperature T1 is lower than the lower limit temperature T2 (T1 < T2) (step S216, no), the process proceeds to step S217. On the other hand, if the determination unit 520 determines that the current temperature T1 is equal to or higher than the lower limit temperature T2 (T1 ≥ T2) (step S216, yes), it is determined that the sub-battery 300 is in a state where it can output backup power for automatic driving, and the measurement control of the fully charged capacity of this sub-battery 300 ends.

[0046] (Step S217) The measurement control unit 540 of the fully charged capacity measurement device 500 performs a temperature increase process on the sub-battery 300. This temperature increase process is, for example, a process of increasing the temperature of the sub-battery 300 by performing a discharge process or a charge process on the sub-battery 300 while maintaining the state of charge rate of the sub-battery 300 near a high state of charge (high SOC) to cause the sub-battery 300 to generate heat. When the measurement control unit 540 performs the temperature increase process on the sub-battery 300, the process proceeds to step S216.

[0047] <Function and Effect> As described above, according to the fully charged capacity measurement device 500 according to an embodiment of the present disclosure, for the sub-battery 300 provided for backup of the main battery 100 that supplies power to loads (the first in-vehicle load 410, the second in-vehicle load 420) including the automatic driving system, when the temperature of the sub-battery 300 is a low temperature at which the operation of the automatic driving system does not occur, the measurement control of the fully charged capacity is performed.

[0048] Through such control, it is possible to measure the fully charged capacity of the sub-battery 300 while maintaining the state of charge rate necessary for backup power supply to systems other than the automatic driving system.

[0049] As described above, one embodiment of the present disclosure has been explained. However, the present disclosure can be understood not only as the fully charged capacity measurement device described above, but also as a control method executed by a fully charged capacity measurement device including a processor and a memory, a control program for the control method, a computer-readable non-transitory recording medium storing the control program, or a vehicle equipped with the fully charged capacity measurement device, etc.

Industrial Applicability

[0050] The fully charged capacity measurement device of the present disclosure can be used when measuring the fully charged capacity of a battery, etc.

Explanation of Signs

[0051] 10 Power supply system 100 Main battery 200 DCDC converter 300 Sub-battery 410 First in-vehicle load 420 Second in-vehicle load 500 Fully charged capacity measurement device 510 Acquisition unit 520 Determination unit 530 Calculation unit 540 Measurement control unit

Claims

1. A full charge capacity measuring device for measuring the full charge capacity of a sub-battery provided for backup of a main battery that supplies power to an automatic driving system, an acquisition unit that acquires the temperature of the sub-battery, a determination unit that determines whether the current temperature of the sub-battery is less than a lower limit temperature, which is the minimum temperature required for the sub-battery for the automatic driving system to execute an automatic driving function, and a measurement control unit that performs measurement control of the full charge capacity of the sub-battery only when the current temperature is less than the lower limit temperature. Full charge capacity measuring device.

2. The full charge capacity measuring device further includes a calculation unit that calculates a first estimated time required until the measurement of the full charge capacity of the sub-battery is completed based on the charge and discharge value that the sub-battery with the current temperature can output, and a second estimated time required for the temperature of the sub-battery to rise from the current temperature to the lower limit temperature by the implementation of the measurement control of the full charge capacity, and the measurement control unit executes the measurement process of the full charge capacity of the sub-battery when the first estimated time is less than the second estimated time. The full charge capacity measuring device according to claim 1.

3. After the measurement control unit starts the measurement process of the full charge capacity of the sub-battery, if the first estimated time recalculated by the calculation unit during the measurement process becomes equal to or greater than the second estimated time, the measurement control unit stops the measurement process of the full charge capacity. The full charge capacity measuring device according to claim 2.

4. After the measurement control unit completes the measurement of the full charge capacity of the sub-battery, it charges the sub-battery until the temperature of the sub-battery reaches the lower limit temperature. The full charge capacity measuring device according to claim 1 or 2.

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