JP7658396B2 - Battery management device and method - Google Patents

Description

This disclosure relates to a battery management device and management method.

Electric vehicles (EVs) and hybrid vehicles are equipped with batteries to supply power to the driving source. Batteries gradually deteriorate with repeated use. Also, the speed of deterioration may increase depending on the battery's usage conditions. Therefore, it is known to predict the degree of battery deterioration based on the battery's usage history.

For example, Patent Document 1 discloses a method for predicting the degree of battery deterioration from a deterioration curve that corresponds to the method of using the battery.

For example, Patent Document 2 discloses a method of correcting the expansion curve and degradation curve based on the usage history and environmental conditions, and predicting the degree of degradation of the battery based on the corrected expansion curve and degradation curve.

JP 2013-084198 A JP 2020-071035 A

However, in the invention described in Patent Document 1, if the predicted value of the deterioration degree deviates significantly from the deterioration curve, it predicts sudden deterioration. Since the predicted value has an error and varies with respect to the deterioration curve, there is a risk of misjudging the deterioration degree of the battery.

Even in the invention described in Patent Document 2, the data on the usage history varies with respect to the deterioration curve, so there is a risk of erroneous judgment of the degree of deterioration of the battery.

The objective of this disclosure is to provide a battery management device and management method that can prevent erroneous determination of the degree of deterioration of a battery.

In order to achieve the above object, the battery management device according to the present disclosure includes:
A battery management device provided for each vehicle equipped with a battery for supplying power to a driving power source,
an acquisition unit that acquires a usage history of the battery and a deterioration level of the battery ;
a calculation unit that calculates an approximation line specific to the vehicle that indicates a relationship between the usage history and the deterioration level based on the usage history and the deterioration level that have been acquired in the past, and calculates a judgment reference line specific to the vehicle with respect to the approximation line based on a variation in the deterioration level that has been acquired in the past;
a determination unit that determines whether the newly acquired deterioration degree is within an allowable range based on the determination reference line ;
Equipped with
If the newly acquired degree of deterioration is within the acceptable range, the determination unit updates the approximation line using the newly acquired degree of deterioration, and if the newly acquired degree of deterioration is outside the acceptable range, the determination unit does not update the approximation line using the newly acquired degree of deterioration.

In addition, the battery management method according to the present disclosure includes:
A method for managing a battery provided for each vehicle equipped with a battery for supplying power to a driving power source, the method comprising:
Acquiring a usage history of the battery and a deterioration level of the battery;
calculating an approximation line specific to the vehicle that indicates a relationship between the usage history and the deterioration degree based on the usage history and the deterioration degree that have been acquired in the past, and calculating a judgment reference line specific to the vehicle with respect to the approximation line based on a variation in the deterioration degree that has been acquired in the past;
determining whether the newly acquired deterioration degree is within an allowable range based on the determination reference line ;
If the newly acquired degree of deterioration is within the acceptable range, the approximation line is updated using the newly acquired degree of deterioration, and if the newly acquired degree of deterioration is outside the acceptable range, the approximation line is not updated using the newly acquired degree of deterioration.

This disclosure makes it possible to prevent erroneous determination of the degree of battery deterioration.

FIG. 1 is a diagram illustrating an example of a battery management device according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating an example of accumulated data accumulated in the storage unit. FIG. 3 is a scatter diagram according to this embodiment. FIG. 4 is a scatter diagram according to a comparative example.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
1 is a diagram illustrating an example of a battery management device according to an embodiment of the present disclosure. The battery management device according to the present embodiment can be applied to commercial vehicles such as trucks and buses, but can also be applied to vehicles such as passenger cars.

The vehicle 10 to which the battery management device of this embodiment is applied is an electric vehicle (EV) or a hybrid vehicle. The EV 10 is equipped with a battery (not shown) for supplying power to a driving power source (motor). The battery gradually deteriorates according to the number of cycles, which is the number of times the battery is repeatedly charged and discharged. It is also known that the deterioration speed of the battery increases according to the usage conditions. In the following explanation, the power supply destination, such as a motor to which power is supplied from the battery, may be referred to as a "load".

EV 10 is provided with a vehicle control unit 30 (Vehicle Control Unit: VCU). VCU 30 judges the state of EV 10 and executes control to maintain EV 10 in an optimal state. Specifically, if VCU 30 detects an abnormality in EV 10, it controls the motor to stop EV 10. VCU 30 monitors the battery and acquires the operating time of the battery. VCU 30 acquires the mileage of EV 10. VCU 30 also controls the power supply from the battery to the load by changing the voltage between the battery and the load. VCU 30 also controls a charger (not shown) so that the charging power when charging the battery does not exceed the chargeable power.

The battery operating time and the driving distance of the EV 10 are sent from the VCU 30 to the battery management device 20.

The battery has a temperature sensor (not shown) and a voltage sensor (not shown). The temperature sensor detects the temperature of the battery and the temperature surrounding the battery. The voltage sensor detects the voltage of the battery.

EV 10 is provided with a monitoring unit 40 that monitors the usage status of the battery. The monitoring unit 40 obtains the detection results of the temperature sensor and the voltage sensor, and identifies the remaining capacity rate (State Of Health: SOH) based on the obtained detection results. The monitoring unit 40 also obtains the number of cycles of the battery. The number of cycles is a parameter that defines the number of charge/discharge cycles in which the battery is discharged from a charge amount equal to or greater than a first remaining amount to a charge amount equal to or less than a second remaining amount, and then charged again to a charge amount equal to or greater than the first remaining amount as 1. Note that the first remaining amount may be higher than the second remaining amount, and the first remaining amount may be considered to be fully charged. The monitoring unit 40 monitors the remaining amount of the battery, etc., and obtains the number of cycles that the battery has gone through.

The monitoring unit 40 performs control to use the battery safely and effectively. Specifically, the monitoring unit 40 controls a relay (not shown) that connects/disconnects the battery and the load based on the detection results of the temperature sensor and the voltage sensor.

The detection results of the temperature sensor and the voltage sensor, the number of cycles, and the SOH are sent from the monitoring unit 40 to the battery management device 20. The detection results of the temperature sensor and the voltage sensor, and the number of cycles correspond to the "battery usage history" in this disclosure. The SOH corresponds to the "degree of deterioration of the battery" in this disclosure.

A battery management device 20 is provided for each vehicle 10. The battery management device 20 includes a control unit 21 and a memory unit 25. In FIG. 1, the arrows indicate the main data flows, and there may be data flows not shown in FIG. 1. In FIG. 1, each functional block indicates a functional configuration, not a hardware (device) configuration. Therefore, the functional blocks shown in FIG. 1 may be implemented in a single device, or may be implemented separately in multiple devices. Data may be exchanged between functional blocks via any means, such as a data bus or a controller area network (CAN bus).

The management device 20 may be provided for multiple vehicles 10. In one example of this case, the management device 20 is provided in a server (not shown). Each of the vehicles 10 and the server has a communication unit, and the vehicles 10 and the server communicate with each other via a network.

The storage unit 25 is a storage device such as a ROM (Read Only Memory) that stores the BIOS (Basic Input System) of the computer that realizes the management device 20, a RAM (Random Access Memory) that serves as the working area of the management device 20, an HDD (Hard Disk Drive) or an SSD (Solid State Drive) that stores the OS (Operating System), application programs, and various information referenced when the application programs are executed.

The control unit 21 is a processor such as a CPU (Central Processing Unit) or a GPU (Graphic Processing Unit) of the management device 20, and functions as an acquisition unit 22, a calculation unit 23, and a determination unit 24 by executing a program stored in the memory unit 25.

Figure 1 shows an example in which the management device 20 is configured as a single device. However, the management device 20 may be realized by, for example, multiple processors, memory, and other computing sources. In this case, each part constituting the control unit 21 is realized by at least one of the multiple different processors executing a program. Note that, when the management device 20 is configured as a single device, the management device 20 may be configured as, for example, all of the VCU 30 and the monitoring unit 40 shown in Figure 1. When the management device 20 is configured as multiple devices, the management device 20 may be configured as, for example, each of the VCU 30 and the monitoring unit 40, or may be configured as a combination of any two devices and one other device.

The acquisition unit 22 acquires the battery usage history (detection results of the temperature sensor and voltage sensor, and the number of cycles) from the monitoring unit 40. The acquisition unit 22 also acquires the SOH from the monitoring unit 40.

The memory unit 25 stores the battery usage history and SOH acquired by the acquisition unit 22. FIG. 2 is a diagram showing an example of accumulated data stored in the memory unit 25. As shown in FIG. 2, the memory unit 25 accumulates data on the SOH, operating time, mileage, and accumulated power for each date. Here, "operating time" is the operating time of the battery, "mileage" is the mileage of the EV 10, and "accumulated power" is the accumulated power consumption of the battery. It can be said that the memory unit 25 stores data on the SOH, operating time, mileage, and accumulated power in association with the timing at which each data was acquired.

The calculation unit 23 calculates an approximation line that indicates the relationship between the usage history and the deterioration level based on the usage history and SOH acquired in the past. Note that, here, the "usage history and deterioration level acquired in the past" refers to the usage history and SOH acquired before the calculation of the approximation line. Also, the "approximation line" is called an approximation curve or a deterioration curve. A publicly known method is used to calculate the approximation line. For example, the calculation unit 23 calculates the approximation line by plotting the accumulated data accumulated in the storage unit 25 on a scatter diagram with the horizontal axis being "date" and the vertical axis being SOH. Note that, in the present disclosure, the accumulated data used to calculate the approximation line is not limited to "date". For example, it may be "mileage" or "accumulated power amount".

Figure 3 is a scatter diagram in this embodiment. In Figure 3, the horizontal axis indicates "date" and the vertical axis indicates "SOH." As shown in Figure 3, the scatter diagram plots SOH corresponding to date. In Figure 3, the plotted SOH are indicated as S11, S12, S13, S14, S15, and S21.

The calculation unit 23 calculates a judgment reference line for the approximation line based on the variation in SOH obtained in the past. Specifically, the calculation unit 23 calculates the "variance" or "standard deviation" that represents the variation in SOH based on a scatter diagram in which the SOH is plotted. The calculation unit 23 calculates the judgment reference line based on the calculated "variance" or "standard deviation." In FIG. 3, the "approximation line La" is shown by a dotted line, the "judgment reference line Lr" is shown by a dashed line, and the "life line Lb (use limit)" is shown by a dashed line.

The calculation unit 23 calculates the approximation line La based on S11, S12, S13, S14, and S15 (hereinafter collectively referred to as S11 to S15), which are the SOH acquired before acquiring the SOH 21. The calculation unit 23 also calculates a judgment reference line Lr for the approximation line La based on the variation in the SOH. For example, the calculation unit 23 multiplies the approximation line La obtained from the past SOH data by a coefficient of 1 or less to obtain the judgment reference line Lr. Here, the coefficient is determined based on the variation in S11 to S15, for example, based on the standard deviation.

The determination unit 24 determines whether the newly acquired SOH is greater than the SOH expected from the determination reference line Lr. The determination unit 24 also updates the approximation line La using the newly acquired SOH according to the determination result. If the newly acquired SOH is greater than the SOH expected from the determination reference line Lr, the determination unit 24 determines that the SOH is within the allowable range for the approximation line La, and updates the approximation line La using the SOH. On the other hand, if the newly acquired SOH is equal to or less than the SOH expected from the determination reference line Lr, the determination unit 24 determines that the SOH is outside the allowable range for the approximation line La, and does not update the approximation line La using the SOH.

Specifically, if the SOH shown in S21 is newly acquired after S11 to S15, the SOH is equal to or lower than the SOH expected from the judgment reference line Lr, so the judgment unit 24 does not update the approximation line La to the approximation line La1 specified using S11 to S15 and S21. In other words, the approximation line calculated based on the plotted SOHs S11, S12, S13, S14, S15, and S21 is not changed from the approximation line La to the approximation line La1. On the other hand, if the SOH (S16, S17) shown in FIG. 3 is newly acquired, the SOH is higher than the SOH expected from the judgment reference line Lr, so the judgment unit 24 updates the approximation line La using the acquired SOH (S16, S17).

The identification unit 26 identifies the estimated life of the battery based on the approximation line La. The identification unit 26 identifies the estimated life Da of the battery from the intersection of the approximation line La and the life line Lb. The identification unit 26 determines the date on which the SOH reaches the life line Lb along the approximation line La as the estimated life Da. In FIG. 3, the plot shown in S30 indicates the SOH corresponding to the estimated life. The estimated life Da identified by the identification unit 26 is stored in the memory unit 25. The estimated life Da is transmitted to a management server that manages the EV 10 via a communication unit (not shown). The estimated life Da may be notified to the user of the EV 10 by displaying it on a display device of the EV 10.

According to the battery management device 20 of this embodiment, when updating the relationship between the battery's usage history and the degree of deterioration from the battery's usage history and the degree of deterioration, and determining the estimated lifespan of the battery based on the relationship, parameters outside the allowable range based on the variation in the battery's usage history and degree of deterioration previously acquired are not used to update the relationship. It is possible to prevent the determined estimated lifespan from changing significantly due to the influence of parameters that have changed significantly temporarily.

Next, a comparative example will be described with reference to FIG. 4. In the comparative example, the judgment reference line Lr is not used to judge whether or not the newly acquired SOH is within the allowable range. FIG. 4 is a scatter plot according to the comparative example. The horizontal axis in FIG. 4 indicates "date," and the vertical axis indicates "SOH." The same reference numerals are used for the components described in FIG. 3, and the description will be omitted.

In the comparative example, the judgment reference line Lr is not calculated. In FIG. 4, the newly acquired SOH, which varies with respect to the approximation line La, is shown as S21. At this time, the calculation unit 23 updates the approximation line from the approximation line La to the approximation line La1 based on the plotted SOHs S11 to S15 and S21. That is, in the comparative example, even if the newly acquired SOH (S21) is significantly different from the variation of the SOH (S11 to S15) acquired up to that point, the SOH is used to calculate the approximation line. Based on the updated approximation line La1, the identification unit 26 identifies the date on which the SOH reaches the life line Lb as the estimated life. As shown in FIG. 4, the identification unit 26 identifies the date Da1 on which the SOH reaches the life line Lb as the estimated life based on the estimated SOH S31. The estimated lifespan obtained in the comparative example is suddenly shortened from the estimated lifespan Da based on the approximation line La calculated in S11 to S15 to the estimated lifespan Da1 based on the approximation line La1 calculated in S11 to S15 and S21. Even if the obtained SOH deviates from the variation in the SOH obtained up to that point, the SOH is used to calculate the approximation line, so the inaccurate SOH due to erroneous detection of the SOH, etc., results in an inaccurate evaluation.

The battery management device 20 in this embodiment includes an acquisition unit 22 that acquires the battery usage history and SOH, a calculation unit 23 that calculates an approximation line La that represents the relationship between the usage history and the SOH based on the usage history and SOH acquired in the past, and a determination unit 24 that determines whether the newly acquired SOH is within an acceptable range for the approximation line La.

With the above configuration, the newly acquired SOH is determined to be within an acceptable range for the approximation line La, making it possible to prevent erroneous determination of the battery's degree of deterioration. In addition, since the approximation line calculated based on the newly acquired SOH is not changed from the approximation line La, it is possible to prevent the battery life estimated based on the approximation line La from being shortened.

In the above embodiment, the judgment reference line Lr is set as the allowable range, where the SOH for the usage history (date) is smaller than the approximation line La, and when the newly acquired SOH is higher than the judgment reference line Lr, it is judged to be within the allowable range, but this is not limited to the above. For example, the judgment reference line Lu may be set as the allowable range, where the SOH for the usage history (date) is larger than the approximation line La, and when the newly acquired SOH is lower than the judgment reference line Lu, it is judged to be within the allowable range. For example, such a setting is effective when the SOH error occurs as a large value.
Furthermore, an upper limit and a lower limit may be set for the approximation line La, and an allowable range may be set that includes the approximation line La. For example, the above-mentioned judgment reference line Lu and judgment reference line Lr may be used as the upper limit and the lower limit, respectively.

In addition, in the battery management device 20 in the above embodiment, the allowable range is set based on the variation in SOH acquired in the past. This allows the allowable range to be adjusted according to the variation in SOH, making it possible to improve the accuracy of determining the deterioration level of the battery. Although the judgment reference line Lr for the approximation line La is set using the variation in SOH, the variation can be determined using known statistics such as the above-mentioned variance and standard deviation. In addition, the allowable range may be set in advance as a fixed value, or can be changed arbitrarily by the user. The allowable range can be set simply as an upper and lower margin set for the approximation line, regardless of the setting of the judgment reference line.
In the above embodiment, the estimated lifespan is determined using an approximation line of the SOH versus date, but this is not limited to the above. The estimated lifespan may be determined using other usage histories, such as the detection results of a temperature sensor, the detection results of a voltage sensor, or an approximation line of the SOH versus the number of cycles.

In addition, in the battery management device 20 in the above embodiment, the calculation unit 23 calculates a judgment reference line Lr for the approximation line La based on the variation in the deterioration level previously obtained, and the judgment unit 24 judges whether or not the newly obtained deterioration level is within an acceptable range based on the judgment reference line Lr. This makes it possible to adjust the judgment reference line Lr according to the variation in SOH, thereby improving the accuracy of the judgment of the deterioration level of the battery.

In addition, the above embodiments are merely examples of concrete ways of implementing the present disclosure, and the technical scope of the present disclosure should not be interpreted in a limiting manner based on them. In other words, the present disclosure can be implemented in various forms without departing from its gist or main features.

This disclosure is suitable for use in vehicles equipped with a battery management device that is required to prevent erroneous determination of the battery's deterioration level.

La Approximation line Lb Life line Lr Judgment reference line 10 Electric vehicle (EV)
20 Battery management device 21 Control unit 22 Acquisition unit 23 Calculation unit 24 Determination unit 25 Storage unit 30 VCU
40 Surveillance Department

Claims (8)

A battery management device provided for each vehicle equipped with a battery for supplying power to a driving power source,
an acquisition unit that acquires a usage history of the battery and a deterioration level of the battery;
a calculation unit that calculates an approximation line specific to the vehicle that indicates a relationship between the usage history and the deterioration level based on the usage history and the deterioration level that have been acquired in the past, and calculates a judgment reference line specific to the vehicle with respect to the approximation line based on a variation in the deterioration level that has been acquired in the past;
a determination unit that determines whether the newly acquired deterioration degree is within an allowable range based on the determination reference line;
Equipped with
the determination unit updates the approximation line using the newly acquired deterioration degree when the newly acquired deterioration degree is within the allowable range, and does not update the approximation line using the newly acquired deterioration degree when the newly acquired deterioration degree is outside the allowable range.
Battery management device. The battery management device according to claim 1 , further comprising a specification unit that specifies an estimated lifespan of the battery using the approximation line. The battery management device according to claim 1 , wherein the usage history of the battery includes at least one of the number of cycles of the battery, the usage time, the temperature of the battery, and the voltage of the battery. The battery management device according to claim 1 , wherein the deterioration level of the battery includes a remaining capacity rate of the battery. A method for managing a battery provided for each vehicle equipped with a battery for supplying power to a driving power source, the method comprising:
Acquiring a usage history of the battery and a deterioration level of the battery;
calculating an approximation line specific to the vehicle that indicates a relationship between the usage history and the deterioration degree based on the usage history and the deterioration degree that have been acquired in the past, and calculating a judgment reference line specific to the vehicle with respect to the approximation line based on a variation in the deterioration degree that has been acquired in the past;
determining whether the newly acquired deterioration degree is within an allowable range based on the determination reference line ;
When the newly acquired deterioration degree is within the allowable range, the approximation line is updated using the newly acquired deterioration degree, and when the newly acquired deterioration degree is outside the allowable range, the approximation line is not updated using the newly acquired deterioration degree.
How to manage the battery. The method of claim 5 , further comprising: determining an estimated lifespan of the battery using the approximation line. The battery management method according to claim 5 , wherein the usage history of the battery includes at least one of a number of cycles of the battery, a usage time, a temperature of the battery, and a voltage of the battery. The battery management method according to claim 5 , wherein the degree of deterioration of the battery includes a remaining capacity rate of the battery.