Battery degradation determination device

Abstract

To provide a technique for appropriately determining degradation of a vehicle battery.SOLUTION: A parking time acquisition unit 34 acquires a parking time of a vehicle. A battery information acquisition unit 36 acquires the voltage value of a vehicle battery 12. A voltage correction unit 38 corrects the acquired voltage value when the parking time is shorter than a predetermined time. A degradation determination unit 40 determines degradation of the vehicle battery 12 on the basis of the corrected voltage value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for determining the deterioration of a vehicle battery. [Background technology]

[0002] Patent Document 1 discloses a battery life prediction system in which various parameters representing the state of a vehicle battery are transmitted from the vehicle to a battery life prediction device each time the vehicle's ignition switch is turned on. The battery life prediction device predicts the remaining life of the vehicle battery based on time-series data of the degradation index of the vehicle battery and a trained prediction model. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-148560 Summary of the Invention [Problem to be solved by the invention]

[0004] In secondary batteries such as vehicle auxiliary batteries, charging causes a concentration difference in the battery fluid, which increases the electromotive force near the electrodes and generates a polarization voltage. Therefore, even after charging is completed, if the voltage of the vehicle battery is measured while the effects of charge polarization remain, the measured voltage value will be higher than the actual value. When using voltage values ​​to determine the deterioration of a vehicle battery, it is assumed that the voltage values ​​measured over time are accurate. Therefore, using voltage values ​​that include the effects of charge polarization makes it difficult to properly perform the deterioration determination process for the vehicle battery.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a technology for appropriately determining the deterioration of a vehicle battery. [Means for solving the problem]

[0006] In order to solve the above problem, a battery deterioration determination device according to one embodiment of the present invention includes a means for acquiring the parking time of a vehicle, a means for acquiring the voltage value of the vehicle battery, a means for correcting the acquired voltage value if the parking time is shorter than a predetermined time, and a means for determining the deterioration of the vehicle battery based on the corrected voltage value. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram illustrating a functional configuration of the battery deterioration determination system. [Figure 2] FIG. 1(a) is a diagram showing the relationship between the voltage value of a vehicle battery and the parking time of the vehicle, FIG. 1(b) is a map showing the relationship between the charge polarization voltage and the elapsed time, and FIG. 1(c) is a diagram showing an example of correction in which the voltage value of the current day is replaced with the voltage value of the previous day. [Figure 3] FIG. 10 is a flowchart showing a process for removing the influence of charging polarization from a voltage value. DETAILED DESCRIPTION OF THE INVENTION

[0008] 1 shows the functional configuration of a battery degradation determination system 1 according to an embodiment. The battery degradation determination system 1 includes a vehicle system 10 mounted on a vehicle and a battery degradation determination device 30 provided outside the vehicle. The battery degradation determination device 30 may be provided as a server device managed by an operator of the battery degradation determination system 1. The vehicle system 10 and the battery degradation determination device 30 are connected to each other so as to be able to communicate with each other via a network 2 such as the Internet.

[0009] The vehicle may be a vehicle that uses only an internal combustion engine as a driving force source, or may be an electrically powered vehicle that uses an electric motor as a driving force source. Electrically powered vehicles include, for example, battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fuel cell electric vehicles (FCEVs). The vehicle may be a vehicle driven by a driver or an autonomous vehicle.

[0010] The vehicle system 10 includes a vehicle battery 12 that supplies power to on-board devices, a sensor 14 that measures the state of the vehicle battery 12, a control unit 16 that performs power supply management including management of the vehicle battery 12, and a communication unit 18 that communicates with an external battery degradation determination device 30. The vehicle battery 12 may be an auxiliary battery that is a rechargeable secondary battery, and may be charged while the vehicle is running.

[0011] The control unit 16 measures the parking time of the vehicle based on the OFF and ON operations of the vehicle's ignition switch. Specifically, when a trip ends, the control unit 16 stores the time when the ignition switch was turned OFF, and the next time the ignition switch is turned ON, measures the time from the OFF operation to the ON operation as the parking time. In this embodiment, the measured parking time corresponds to the time when the vehicle battery 12 was not charged (non-charging time).

[0012] The sensor 14 measures various parameters indicating the battery state, such as the voltage value, current value, temperature, and charge amount of the vehicle battery 12. The sensor 14 may measure the air temperature as a parameter indicating the battery state, instead of the temperature of the vehicle battery 12. The sensor 14 supplies the various measured parameters to the control unit 16. Note that some or all of the various parameters may be measured by the control unit 16.

[0013] When the vehicle ignition switch is turned on, the control unit 16 collects various parameters indicating the battery state as battery information. When the vehicle ignition switch is turned on, the control unit 16 transmits the measured parking time and the collected battery information to the battery degradation determination device 30 via the communication unit 18.

[0014] The battery degradation determination device 30 includes a communication unit 32, a parking time acquisition unit 34, a battery information acquisition unit 36, a voltage correction unit 38, and a degradation determination unit 40. When the communication unit 32 receives the parking time and battery information transmitted from the vehicle, the parking time acquisition unit 34 acquires the parking time of the vehicle, and the battery information acquisition unit 36 ​​acquires battery information indicating the state of the vehicle battery 12. If multiple trips are made in a day, the parking time acquisition unit 34 and the battery information acquisition unit 36 ​​acquire the parking time and battery information, respectively, at the start of each trip.

[0015] 2(a) shows the relationship between the voltage value of the vehicle battery and the parking time of the vehicle. Fig. 2(a) shows the relationship between the voltage value and the parking time acquired over a 10-day period. If the communication unit 32 receives parking time and battery information from the same vehicle multiple times in a day, the lowest voltage value for that day and the parking time received together with that voltage value are also shown.

[0016] When the vehicle battery 12 is charged, a concentration difference occurs in the battery fluid, causing an increase in electromotive force near the electrodes and generating a polarization voltage. Therefore, even after charging is completed, if the voltage of the vehicle battery is measured while the effects of charge polarization remain, the measured voltage will be higher than the actual voltage. Because the vehicle battery 12 is charged while the vehicle is running, if the time between turning the ignition switch off and the next time it is turned on (non-charging time) is short, the voltage measured when the ignition switch is turned on will include a voltage value due to charge polarization, resulting in a voltage value higher than the actual voltage.

[0017] Figure 2(b) is a map showing the relationship between charge polarization voltage and the time elapsed since the end of charging for each battery liquid temperature. This map may be derived by statistically processing battery information collected from many vehicles in the past. As shown in this map, at each battery liquid temperature, a very large charge polarization voltage remains within 0.5 hours after the end of charging, while charge polarization is almost completely eliminated 6 hours after the end of charging. In terms of the relationship with battery liquid temperature, the higher the battery liquid temperature, the more quickly the effects of charge polarization tend to converge.

[0018] Looking at the voltage values ​​over the 10 days shown in Figure 2(a), the minimum voltage value fluctuates significantly from day to day. This is thought to be because the parking time (non-charging time) was short on the second, fourth, sixth, eighth, and tenth days, and charge polarization had not yet been resolved when the voltage was measured. Therefore, it is preferable for the battery degradation determination device 30 to remove the effects of charge polarization from the measured voltage value.

[0019] FIG. 3 shows a flowchart for removing the effects of charge polarization from voltage values. The voltage correction unit 38 determines whether the parking time for one day is less than a predetermined time T (S10). The predetermined time T is set to a time that allows charge polarization to be sufficiently eliminated, and may be, for example, six hours. If the parking time for one day is equal to or greater than the predetermined time T (N in S10), charge polarization is eliminated, and the measured voltage value is not affected by charge polarization. Therefore, the voltage correction unit 38 does not correct the measured voltage value. Referring to FIG. 2(a), since the parking time on the first, third, fifth, seventh, and ninth days is six hours or more, the voltage correction unit 38 does not correct the voltage values ​​measured on the first, third, fifth, seventh, and ninth days.

[0020] On the other hand, if the parking time for one day is less than the predetermined time T (Y in S10), the measured voltage value may be affected by charge polarization. In FIG. 2(a), the parking time on the second, fourth, sixth, eighth, and tenth days is less than six hours, and the voltage values ​​measured on these days may contain charge polarization voltage. Therefore, the voltage correction unit 38 compares the voltage value for that day with the voltage value for the previous day and determines whether the voltage value for that day is higher than the voltage value for the previous day (S12). If the voltage value for that day is equal to or lower than the voltage value for the previous day (N in S12), it is determined that the voltage value for that day does not contain charge polarization voltage, and therefore the voltage correction unit 38 does not correct the voltage value for that day.

[0021] On the other hand, if the voltage value on the current day is higher than the voltage value on the previous day (Y in S12), the voltage correction unit 38 determines that the voltage value on the current day includes a charge polarization voltage. In Fig. 2(a), the voltage values ​​on the second, fourth, sixth, eighth, and tenth days are higher than the voltage values ​​on the first, third, fifth, seventh, and ninth days, respectively. Therefore, the voltage correction unit 38 performs a correction process to remove the influence of charge polarization from the voltage values ​​on the second, fourth, sixth, eighth, and tenth days.

[0022] For example, the voltage correction unit 38 may perform a correction process to replace the voltage value of the current day with the voltage value of the previous day. Thus, the voltage correction unit 38 changes the voltage value of the second day to the voltage value of the first day, the voltage value of the fourth day to the voltage value of the third day, the voltage value of the sixth day to the voltage value of the fifth day, the voltage value of the eighth day to the voltage value of the seventh day, and the voltage value of the tenth day to the voltage value of the ninth day. Figure 2(c) shows an example of a correction in which the voltage values ​​on the second, fourth, sixth, eighth, and tenth days are replaced with the voltage values ​​of the previous days. By performing a correction process to replace the voltage values ​​in this way, the effects of charge polarization can be removed from the voltage values.

[0023] The degradation determination unit 40 determines the degradation of the vehicle battery 12 based on the corrected voltage value. For example, the degradation determination unit 40 may input the corrected voltage value into a trained prediction model disclosed in Patent Document 1 to determine the degradation of the vehicle battery 12. The degradation determination unit 40 can appropriately perform the degradation determination by using a voltage value from which the influence of charge polarization has been removed. Note that the degradation determination unit 40 may also determine the degradation of the vehicle battery 12 using a different determination method based on the corrected voltage value.

[0024] The voltage correction unit 38 may correct the voltage value based on the parking time and / or battery temperature. In this case, the voltage correction unit 38 may use the map shown in Figure 2(b) to derive the voltage value due to charge polarization from the parking time and / or battery temperature, and perform correction processing to subtract the voltage value due to charge polarization from the measured voltage value. The voltage correction unit 38 may also correct the voltage value using air temperature instead of battery temperature.

[0025] The present invention has been described above based on the embodiments. However, the embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each treatment process, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0026] 1···Battery deterioration determination system, 2···Network, 10···Vehicle system, 12···Vehicle battery, 14···Sensor, 16···Control unit, 18···Communication unit, 30···Battery deterioration determination device, 32···Communication unit, 34···Parking time acquisition unit, 36···Battery information acquisition unit, 38···Voltage correction unit, 40···Deterioration determination unit

Claims

[Claim 1] A means for obtaining a parking time of the vehicle; means for acquiring a voltage value of a vehicle battery; means for correcting the acquired voltage value when the parking time is shorter than a predetermined time; a means for determining deterioration of the vehicle battery based on the corrected voltage value; A battery deterioration determination device comprising:

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