Method and device for determining SOH (state of health) of battery and vehicle

Abstract

The invention provides a battery SOH determination method and device and a vehicle. The method for determining the SOH of the battery comprises the following steps: acquiring the actual ampere-hour quantity of the battery from a preset electric quantity to a full electric quantity in a battery charging process; determining the actual value of the SOH of the battery according to the actual ampere-hour quantity; and according to the actual value of the SOH of the battery, the theoretical value of the SOH of the battery and the forgetting factor, determining the current value of the SOH of the battery. In the process of determining the SOH of the battery, the actual value of the SOH of the battery, the theoretical value of the SOH of the battery and the forgetting factor are considered, and the influence degree of the actual value of the SOH and the theoretical value of the SOH of the battery on the current value of the SOH of the battery can be determined through the forgetting factor, so that the current value of the SOH is more accurate.

Description

Technical Field

[0001] The present application relates to the technical field of estimating the health degree of a battery, and particularly to a method and device for determining the SOH of a battery and a vehicle. Background Art

[0002] With the popularization of new energy vehicles, the safety, stability, and performance of battery management systems have become hot research topics. Among them, the State of Health (SOH) of a battery, as a quantitative index of the health state of the battery, intuitively characterizes the aging degree of the battery. The SOH is defined as the ratio of the current capacity (fully charged or fully discharged) of the battery to the rated capacity at the time of leaving the factory. Generally, it is considered that when the SOH decays to 70%, the battery reaches the end of its service life, and at this time, a new battery needs to be replaced, otherwise there will be a risk in use.

[0003] Therefore, accurately estimating the SOH is of extremely important significance for the use and management of batteries. Currently, the general method is to estimate the SOH of the battery through the State of Charge (SOC) of the battery. At the same time, the SOH of the battery will inversely affect the calculation of the SOC of the battery. When the data quality is poor and the SOC of the battery is inaccurate, the convergence condition cannot be achieved, resulting in calculation divergence and a large deviation in the estimated SOH of the battery. Summary of the Invention

[0004] The present application provides a method and device for determining the SOH of a battery with high accuracy and a vehicle.

[0005] The present application provides a method for determining the SOH of a battery, including:

[0006] During the charging process of the battery, obtaining the actual ampere-hour amount of the battery from a preset power to a full charge;

[0007] Determining the actual value of the SOH of the battery according to the actual ampere-hour amount;

[0008] Determining the current value of the SOH of the battery according to the actual value of the SOH of the battery, the theoretical value of the SOH of the battery, and a forgetting factor.

[0009] Optionally, the forgetting factor is determined according to the current performance parameters of the battery; the current performance parameters include at least one of the cumulative charge and discharge times, the cumulative charge and discharge power, the temperature, the model, and the charge and discharge rate.

[0010] Optionally, the forgetting factor is determined through the following steps:

[0011] For different current performance parameters, obtaining multiple groups of the theoretical value of the SOH of the battery and the corresponding actual value of the SOH of the battery;

[0012] Input the theoretical values of the SOH of multiple groups of the batteries and the corresponding actual values of the SOH of the batteries into the training model to obtain the corresponding relationship between the theoretical values of the SOH of the batteries and the corresponding actual values of the SOH of the batteries under different current performance parameters;

[0013] Determine the forgetting factor according to the corresponding relationship between the theoretical values of the SOH of the batteries and the corresponding actual values of the SOH of the batteries under different current performance parameters.

[0014] Optionally, the determining the current value of the SOH of the battery according to the actual value of the SOH of the battery, the theoretical value of the SOH of the battery, and the forgetting factor includes:

[0015] Determine the current value of the SOH of the battery according to the following formula;

[0016] SOH 当前 =α*SOH 理论 +(1 - α)*SOH 实际

[0017] where SOH 当前 is the current value of the SOH of the battery, SOH 理论 is the theoretical value of the SOH of the battery, SOH 实际 is the actual value of the SOH of the battery, and α is the forgetting factor.

[0018] Optionally, the value range of the forgetting factor is: 75% ≤ α ≤ 85%.

[0019] Optionally, the determining the actual value of the SOH of the battery according to the actual ampere - hour quantity includes:

[0020] Determine the theoretical ampere - hour quantity of the battery from the preset power to the full power according to the theoretical value of the SOH of the battery;

[0021] Determine the actual value of the SOH of the battery according to the theoretical ampere - hour quantity, the actual ampere - hour quantity, and the theoretical value of the SOH of the battery.

[0022] Optionally, the preset power is between 95% of the full power and the full power.

[0023] This application provides a computer - readable storage medium, on which a program is stored. When the program is executed by a processor, the method for determining the SOH of the battery described in any one of the above is implemented.

[0024] This application provides a device for determining the SOH of a battery, including one or more processors for implementing the method for determining the SOH of the battery described in any one of the above.

[0025] The present application also provides a vehicle, including:

[0026] a battery; and

[0027] a determining device for the SOH of the battery as described above, electrically connected to the battery.

[0028] In some embodiments, during the charging process of the battery, the actual ampere-hour amount of the battery from a preset power to full power is obtained; according to the actual ampere-hour amount, the actual value of the SOH of the battery is determined; according to the actual value of the SOH of the battery, the theoretical value of the SOH of the battery, and the forgetting factor, the current value of the SOH of the battery is determined; through the forgetting factor, the influence degree of the actual value of the SOH and the theoretical value of the SOH of the battery on the current value of the SOH of the battery can be determined, making the current value of the SOH more accurate.

[0029] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0031] Figure 1 Shown is a flowchart of an embodiment of a method for determining the SOH of the battery of the present application.

[0032] Figure 2 Shown is a schematic diagram of the SOC change of the battery during the charging process.

[0033] Figure 3 Shown is a schematic diagram of the voltage change of the battery during the charging process.

[0034] Figure 4 Shown is a schematic diagram of the aging curve of the battery.

[0035] Figure 5 Shown is a structural block diagram of an embodiment of a device for determining the SOH of the battery of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The present application provides a method, a device, and a vehicle for determining the SOH of a battery. The following will describe in detail the method, the device, and the vehicle for determining the SOH of the battery of the present application with reference to the accompanying drawings. Without conflict, the features in the following embodiments and implementation manners can be combined with each other.

[0037] Figure 1 Shown is a flowchart of an embodiment of a method 10 for determining the SOH of the battery of the present application. As Figure 1As shown, the method 10 for determining the SOH of a battery includes steps 11 to 13.

[0038] Step 11, during the charging process of the battery, obtain the actual ampere-hour amount of the battery from a preset power level to a full charge.

[0039] The preset power level is less than the full charge. During the charging process of the battery, starting from when the battery charge reaches the preset power level until the battery charge reaches the full charge, determine the actual ampere-hour amount received by the battery. The actual ampere-hour amount reflects the actual amount of electricity received by the battery.

[0040] The actual ampere-hour amount can be determined by formula (1).

[0041]

[0042] Where, △Ah 实际 is the actual ampere-hour amount, t1 is the moment when the battery charge reaches the preset power level, and t2 is the moment when the battery charge reaches the full charge.

[0043] Figure 2 Shown is a schematic diagram of the change in the SOC of the battery during the charging process.

[0044] Figure 3 Shown is a schematic diagram of the change in the voltage of the battery during the charging process.

[0045] In some embodiments, the preset power level is between 95% of the full charge and the full charge.

[0046] Estimating the SOH of the battery requires relying on the voltage-current characteristics of the battery. As Figure 3 shown, in the early stage of battery charging, that is, when the SOC of the battery is small, the voltage change of the battery is small, while in the later stage of battery charging, that is, when the SOC of the battery is large, the voltage change of the battery is large. Therefore, setting the preset power level as the battery being in the later stage of charging can obtain more effective data and improve the accuracy of battery SOH estimation.

[0047] In some embodiments, the preset power level is 99% of the full charge. In this way, the actual ampere-hour amount of the battery from the preset power level to the full charge can be obtained relatively quickly, improving the processing speed.

[0048] Step 12, determine the actual value of the SOH of the battery according to the actual ampere-hour amount.

[0049] The actual ampere-hour amount reflects the actual value of the SOH of the battery.

[0050] In some embodiments, step 12 includes:

[0051] According to the theoretical value of the SOH of the battery, determine the theoretical ampere-hour amount of the battery from the preset power level to the full charge;

[0052] Determine the actual value of the battery's SOH based on the theoretical ampere-hour quantity, the actual ampere-hour quantity, and the theoretical value of the battery's SOH.

[0053] The theoretical ampere-hour quantity of the battery from the preset power level to the full power level can be determined by formula (2).

[0054] △Ah 理论 = SOH 理论 *C 额定 *(1 - preset power level / full power level) Formula (2)

[0055] Where, △Ah 理论 is the theoretical ampere-hour quantity, SOH 理论 is the theoretical value of the battery's SOH, C 额定 is the rated capacity of the battery.

[0056] The theoretical value of the battery's SOH and the rated capacity of the battery are known quantities.

[0057] The actual value of the battery's SOH can be determined by formula (3).

[0058]

[0059] Where, SOH 实际 is the actual value of the battery's SOH.

[0060] Step 13, determine the current value of the battery's SOH based on the actual value of the battery's SOH, the theoretical value of the battery's SOH, and the forgetting factor.

[0061] After obtaining the actual value of the battery's SOH and the theoretical value of the battery's SOH, determine the current value of the battery's SOH according to the forgetting factor. The forgetting factor is used to adjust the influence degree of the actual value of the battery's SOH and the theoretical value of the battery's SOH on the current value of the battery's SOH. The forgetting factor can be a static value determined according to the aging model of the pre-tested battery, or a dynamic value that changes with the actual operating conditions of the battery. The forgetting factor can reflect the changing trend of the battery performance over time. During multiple charging processes of the battery, the SOH of the battery can be dynamically determined according to the forgetting factor, avoiding the problem of large deviation caused by estimating the SOH through the SOC of the battery.

[0062] By comprehensively considering the actual value of the battery's SOH, the theoretical value of the battery's SOH, and the forgetting factor, the current value of the battery's SOH can be determined more accurately, and the health state of the battery can be predicted better.

[0063] In some embodiments, during the process of battery charging, the actual ampere-hour amount of the battery from a preset power level to a full charge is obtained; according to the actual ampere-hour amount, the actual value of the SOH of the battery is determined; according to the actual value of the SOH of the battery, the theoretical value of the SOH of the battery, and the forgetting factor, the current value of the SOH of the battery is determined; the forgetting factor can determine the influence degree of the actual value of the SOH and the theoretical value of the SOH of the battery on the current value of the SOH of the battery, making the current value of the SOH more accurate.

[0064] In some embodiments, the method 10 for determining the SOH of the battery further includes: during the process of battery charging, before the battery reaches the preset power level, the current value of the SOH of the battery is determined according to the OCV (Open Circuit Voltage) of the battery. The current value of the SOH of the battery is estimated by analyzing the change in the shape of the OCV curve of the battery under different aging degrees.

[0065] In some embodiments, the forgetting factor is determined according to the current performance parameters of the battery; the current performance parameters include at least one of the cumulative charge-discharge times, the cumulative charge-discharge power, the temperature, the model, and the charge-discharge rate.

[0066] As the number of charge-discharge cycles increases, irreversible changes will occur in the internal structure and chemical composition of the battery, resulting in a decrease in capacity and performance degradation. Therefore, the cumulative charge-discharge times is an important indicator for measuring the aging degree of the battery. Determining the forgetting factor according to the cumulative charge-discharge times enables the forgetting factor to adapt to the aging degree of the battery and better conform to the current state of the battery.

[0067] The cumulative charge-discharge power is also an important indicator reflecting the usage degree and degradation state of the battery. A high cumulative charge-discharge power requires more charge transfer, accelerating the physical and chemical processes inside the battery and possibly causing accelerated performance degradation of the battery. Determining the forgetting factor according to the cumulative charge-discharge power can also make the forgetting factor reflect the aging degree of the battery.

[0068] The operating temperature of the battery has a significant impact on the performance of the battery. High temperature will accelerate the aging process of the battery, while low temperature may cause a temporary decrease in battery performance. Therefore, the temperature information of the battery is a key factor for adjusting the forgetting factor.

[0069] Batteries of different models have different design characteristics and expected lifetimes. For example, certain types of lithium-ion batteries may be more suitable for high-energy-density applications, while other types may be more suitable for applications requiring long cycle lifetimes. Determining the forgetting factor according to the model of the battery enables the forgetting factor to reflect the performance characteristics of different types of batteries.

[0070] The charge and discharge rate refers to the ratio of the magnitude of the battery's charge and discharge current to the rated capacity of the battery. High-rate charge and discharge will cause greater stress on the battery and accelerate battery degradation. Therefore, determining the forgetting factor based on the charge and discharge rate helps to more accurately evaluate the current health status of the battery.

[0071] In some embodiments, the forgetting factor is determined through the following steps:

[0072] For different current performance parameters, obtain multiple sets of theoretical values of the SOH of the battery and the corresponding actual values of the SOH of the battery;

[0073] Input the multiple sets of theoretical values of the SOH of the battery and the corresponding actual values of the SOH of the battery into the training model to obtain the correspondence between the theoretical values of the SOH of the battery and the corresponding actual values of the SOH of the battery under different current performance parameters;

[0074] Determine the forgetting factor according to the correspondence between the theoretical values of the SOH of the battery and the corresponding actual values of the SOH of the battery under different current performance parameters.

[0075] The theoretical value of the SOH is a known quantity, and the actual value of the SOH can be obtained through experimental measurement. Design multiple sets of different current performance parameters, such as different cumulative charge and discharge times, cumulative charge and discharge amounts, temperatures, battery models, etc., and measure the actual values of the SOH of the battery respectively.

[0076] Take the multiple sets of theoretical values of the SOH of the battery and the actual values of the SOH as the training data set and input them into the training model to train the model so that the model learns the relationship between the theoretical value of the SOH and the actual value of the SOH, that is, how the theoretical value of the SOH is associated with the actual value of the SOH under different current performance parameters. The training model includes but is not limited to linear regression models, non-linear regression models, neural network models, etc. According to the obtained data of the multiple sets of theoretical values of the SOH of the battery and the corresponding actual values of the SOH of the battery, the corresponding training model can be selected.

[0077] After the model training is completed, by analyzing the accuracy of the model's prediction of the current value of the SOH of the battery under different current performance parameters, a suitable forgetting factor can be determined. The forgetting factor is used to adjust the weights of the theoretical value of the SOH and the actual value of the SOH when predicting the current value of the SOH of the battery.

[0078] Through the machine learning model, a more accurate forgetting factor can be obtained, so as to more accurately predict the current value of the SOH of the battery.

[0079] In some embodiments, step 13 includes: determining the current value of the SOH of the battery according to formula (4);

[0080] SOH 当前 = α * SOH 理论 + (1 - α) * SOH 实际 Formula (4)

[0081] Wherein, SOH 当前 is the current value of the SOH of the battery, SOH 理论 is the theoretical value of the SOH of the battery, SOH 实际 is the actual value of the SOH of the battery, and α is the forgetting factor.

[0082] The forgetting factor can be a static value obtained based on experience or experiments. Determining the forgetting factor as a static value can quickly obtain the current value of the SOH of the battery according to the theoretical value of the SOH of the battery and the actual value of the SOH of the battery, improving the data processing speed. According to Formula (4), the larger the forgetting factor α, the closer the current value of SOH is to the theoretical value of SOH, and the smaller the forgetting factor α, the closer the current value of SOH is to the actual value of SOH.

[0083] In some embodiments, the value range of the forgetting factor is: 75% ≤ α ≤ 85%. Preferably, the forgetting factor is 80%.

[0084] The specific value of the forgetting factor can be obtained through data fitting. According to prior knowledge, the SOH of the battery usually gradually decays from 100% to 80% along with 3000 full charges. Figure 4 The following is a schematic diagram of the aging curve of the battery of the present application, wherein the abscissa is the cumulative number of full charges, and the ordinate is the SOH of the battery. The aging curve of the battery can be obtained according to test data or experience. According to the Figure 4 aging curve of the battery shown below, the SOH after each full charge of the battery is obtained, and the numerical value of SOH is substituted into Formula (4) to obtain Formula (5).

[0085] SOH 当前1 = α * SOH 理论1 + (1 - α) * SOH 实际1 ;

[0086] SOH 当前2 = α * SOH 理论2 + (1 - α) * SOH 实际2 ;

[0087] ……… Formula (5)

[0088] SOH 当前3000 = α * SOH 理论3000 + (1 - α) * SOH 实际3000 .

[0089] Wherein, SOH 当前1 = SOH 实际1= 100%; SOH 当前3000 = SOH 实际3000 = 80%; SOH 当前1 ~ SOH 当前3000 The value is obtained from the aging curve of the battery.

[0090] By performing data fitting on formula (5), the forgetting factor α = 0.8021 can be obtained.

[0091] Figure 5 The following shows a structural block diagram of an embodiment of the SOH determination device for the battery of the present application.

[0092] As Figure 5 shown, the SOH determination device for the battery includes one or more processors 21 for implementing the SOH determination method 10 for the battery as described above.

[0093] In some embodiments, the SOH determination device for the battery may include a computer-readable storage medium 22. The computer-readable storage medium 22 may store a program that can be called by the processor 21 and may include a non-volatile storage medium. In some embodiments, the SOH determination device for the battery may include a memory 23 and an interface 24. In some embodiments, the SOH determination device for the battery may also include other hardware according to actual applications.

[0094] The computer-readable storage medium 22 of the embodiment of the present application stores a program thereon. When the program is executed by the processor 21, it is used to implement the SOH determination method 10 for the battery as described above.

[0095] The present application may be in the form of a computer program product implemented on one or more computer-readable storage media 22 (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing program codes. The computer-readable storage media 22 include permanent and non-permanent, removable and non-removable media and may implement information storage by any method or technology. The information may be computer-readable instructions, data structures, program modules, or other data. Examples of the computer-readable storage media 22 include but are not limited to: phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information accessible by a computing device.

[0096] The present application further provides a vehicle, including: a battery and a determination device for the SOH of the battery as described above. The determination device for the SOH of the battery is electrically connected to the battery and is used to determine the current value of the SOH of the battery.

Claims

1. A method for determining the SOH of a battery, characterized in that: include: During the charging process of the battery, obtaining the actual ampere-hour of the battery from a preset power level to a full power level; Determining an actual value of the SOH of the battery according to the actual ampere-hour value; The current value of the SOH of the battery is determined according to the actual value of the SOH of the battery, the theoretical value of the SOH of the battery, and a forgetting factor.

2. The method for determining the SOH of a battery according to claim 1, characterized in that: The forgetting factor is determined according to the current performance parameters of the battery; the current performance parameters include at least one of the cumulative number of charge and discharge times, the cumulative charge and discharge quantity, the temperature, the model, and the charge and discharge rate.

3. The method for determining the SOH of a battery according to claim 1, characterized in that: The forgetting factor is determined by the following steps: For different current performance parameters, obtaining theoretical values ​​of SOH of multiple groups of the batteries and corresponding actual values ​​of SOH of the batteries; Inputting multiple groups of theoretical values ​​of the SOH of the battery and corresponding actual values ​​of the SOH of the battery into a training model to obtain a corresponding relationship between the theoretical value of the SOH of the battery and the corresponding actual value of the SOH of the battery under different current performance parameters; The forgetting factor is determined according to a corresponding relationship between a theoretical value of the SOH of the battery and a corresponding actual value of the SOH of the battery under different current performance parameters.

4. The method for determining the SOH of a battery according to claim 1, characterized in that: The determining the current value of the SOH of the battery according to the actual value of the SOH of the battery, the theoretical value of the SOH of the battery, and the forgetting factor includes: According to the following formula, the current value of the SOH of the battery is determined; SOH 当前 =α*SOH 理论 +(1-α)*SO 3 H 实际 Among them, SOH 当前 is the current value of the battery's SOH, SOH 理论 is the theoretical value of the SOH of the battery, SOH 实际 is the actual value of the SOH of the battery, and α is the forgetting factor.

5. The method for determining the SOH of a battery according to claim 4, characterized in that: The value range of the forgetting factor is: 75%≤α≤85%.

6. The method for determining the SOH of a battery according to claim 1, characterized in that: Determining the actual value of the SOH of the battery according to the actual ampere-hour value includes: Determining a theoretical ampere-hour of the battery from a preset power level to a full power level according to a theoretical value of the SOH of the battery; An actual value of the SOH of the battery is determined according to the theoretical ampere-hour value, the actual ampere-hour value, and a theoretical value of the SOH of the battery.

7. The method for determining the SOH of a battery according to claim 1, characterized in that: The preset power level is between 95% of the full power level and the full power level.

8. A computer-readable storage medium, characterized in that: A program is stored thereon, and when the program is executed by a processor, the method for determining the SOH of a battery according to any one of claims 1 to 7 is implemented.

9. A device for determining the SOH of a battery, characterized in that: The method comprises one or more processors for implementing the method for determining the SOH of a battery according to any one of claims 1 to 7.

10. A vehicle, characterized in that: include: Battery; and The device for determining the SOH of a battery as claimed in claim 9, electrically connected to the battery.

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