Battery capacity difference evaluation method and device, electronic equipment and readable storage medium

Abstract

The invention discloses a battery capacity difference evaluation method, a battery is a lithium iron phosphate battery, the battery comprises a plurality of battery cell monomers, and the evaluation method comprises the following steps: respectively determining a first voltage difference, a first battery charge state, a second battery charge state, a second voltage difference and a first battery charge state variation of the battery in two charging processes; determining a first capacity difference coefficient of the battery according to a difference value between the first battery charge state and the second battery charge state in each charging process; determining a first capacity difference proportionality coefficient and a second capacity difference proportionality coefficient in the two charging processes of the battery according to the first capacity difference coefficient, the first voltage difference, the second voltage difference and the first battery charge state variable quantity; and evaluating the attenuation degree of the battery capacity difference according to the difference between the first capacity difference proportionality coefficient and the second capacity difference proportionality coefficient. The method is more accurate in battery capacity difference evaluation. The invention further discloses a battery capacity difference evaluation device, electronic equipment and a computer readable storage medium.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a method for evaluating battery capacity difference, a device for evaluating battery capacity difference, an electronic device, and a computer-readable storage medium. Background Art

[0002] In the field of new energy storage products, such as new energy vehicles, the problem of poor battery capacity has always been a difficult problem that has plagued relevant battery manufacturers and technical R&D personnel. There are usually multiple battery cells in the battery, and the consistency between each battery cell is poor. The battery state of charge (SOC) of each battery cell is different, and there are differences in the capacity of multiple battery cells in the battery. In actual use, the battery will discharge. When the voltage of a certain battery cell among all the battery cells in the battery drops to a certain level, further discharge will be prohibited. The problem of poor capacity of multiple battery cells in the battery will not only lead to a decline in battery performance, but also shorten the battery life. The problem of poor battery capacity will have a huge impact on the reputation and market influence of the relevant manufacturers' brands. It is necessary to further establish and improve the control and evaluation methods of poor battery capacity.

[0003] At present, lithium iron phosphate batteries are widely used in the field of new energy vehicles. When evaluating the capacity difference of lithium iron phosphate batteries, the existing technology usually directly calculates the size of the capacity difference in each charging process and evaluates based on the size of the capacity difference. When calculating the capacity difference, the existing technology only considers the change in the battery's state of charge, or only considers the change in current and voltage. However, due to the characteristics of lithium iron phosphate batteries, there will be a long plateau period in the voltage change during the charging process, which makes it difficult to accurately calculate the change in the battery's state of charge, and it is also difficult to accurately calculate the change in current or voltage, which leads to inaccurate calculation of the capacity difference. Due to the inaccurate calculation of the capacity difference, it is also difficult for the existing technology to accurately evaluate the capacity difference attenuation of the battery during use. Summary of the invention

[0004] The present invention proposes a method for evaluating battery capacity difference to solve the above problem.

[0005] In a first aspect, an embodiment of the present invention discloses a method for evaluating battery capacity difference, wherein the battery is a lithium iron phosphate battery, and the battery includes a plurality of battery cells. The evaluation method includes:

[0006] Respectively determining a first voltage difference, a first battery state of charge, a second battery state of charge, a second voltage difference and a change in the first battery state of charge during two charging processes of the battery;

[0007] Among them, the battery can obtain a maximum cell single-cell voltage change curve during each charging process, the maximum cell single-cell voltage change curve is a curve composed of the maximum cell single-cell voltages of all cell single-cells of the battery at multiple moments during the charging process and has a first plateau period and a second plateau period, the first voltage difference is the difference between the maximum cell single-cell voltage and the minimum cell single-cell voltage corresponding to the beginning of the first plateau period of the maximum cell single-cell voltage change curve, the first battery state of charge is the battery state of charge corresponding to the end of the first plateau period of the maximum cell single-cell voltage change curve, the second battery state of charge is the battery state of charge corresponding to the beginning of the second plateau period of the maximum cell single-cell voltage change curve, the second voltage difference is the difference between the maximum cell single-cell voltage and the minimum cell single-cell voltage corresponding to the end of the second plateau period of the maximum cell single-cell voltage change curve, and the first battery state of charge change amount is the change amount of the battery state of charge jump when the maximum cell single-cell voltage of the battery exceeds the battery full voltage threshold during the charging process;

[0008] Determine a first capacity difference coefficient of the battery in each charging process according to a difference between a first battery state of charge and a second battery state of charge in each charging process;

[0009] The first capacity difference coefficient is used to reflect the capacity difference of the battery during each charging process;

[0010] Determine a capacity difference proportional coefficient of the battery in each charging process according to the first capacity difference coefficient, the first voltage difference, the second voltage difference and the change in the first battery state of charge in each charging process, which are respectively recorded as the first capacity difference proportional coefficient and the second capacity difference proportional coefficient;

[0011] The attenuation degree of the battery capacity difference is evaluated according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient.

[0012] By adopting the above technical scheme, the battery capacity difference evaluation method of the present invention determines the change amount of the battery state of charge in the time period through the battery state of charge corresponding to the end of the first plateau period and the beginning of the second plateau period of the highest battery cell voltage change curve, so as to determine the battery capacity difference. Since the battery capacity difference does not change during each charging process, the present invention also establishes the capacity difference proportional coefficient of the battery during each charging process by determining the battery capacity difference corresponding to the beginning of the first plateau period and the end of the second plateau period of the highest battery cell voltage change curve, thereby reducing the influence of errors or other influencing factors on the capacity difference calculation, and the change of the capacity difference proportional coefficient during different charging processes can more accurately evaluate the attenuation degree of the battery capacity difference during use.

[0013] According to another specific embodiment of the present invention, determining a first capacity difference coefficient of a battery in each charging process according to a difference between a first battery state of charge and a second battery state of charge in each charging process specifically includes:

[0014] Determine the temperature variation coefficient from the end of the first plateau period to the beginning of the second plateau period of the maximum cell voltage variation curve during each charging process; the temperature variation coefficient is used to indicate the degree of change of the battery temperature with the maximum cell voltage from the end of the first plateau period to the beginning of the second plateau period;

[0015] A first capacity difference coefficient of the battery in each charging process is determined according to the temperature variation coefficient in each charging process and the difference between the first battery state of charge and the second battery state of charge.

[0016] According to another specific embodiment of the present invention, determining the temperature variation coefficient from the end of the first plateau period to the beginning of the second plateau period of the maximum cell voltage variation curve during each charging process specifically includes:

[0017] Determine the first minimum temperature of all the battery cells in the battery corresponding to the end of the first plateau period of the maximum battery cell voltage change curve during each charging process, and the second maximum temperature of all the battery cells in the battery corresponding to the beginning of the second plateau period;

[0018] Determine the basic temperature variation coefficient according to the variation of the maximum cell voltage with the battery temperature in the first plateau period of the maximum cell voltage variation curve;

[0019] The temperature variation coefficient is determined according to the difference between the first minimum temperature and the second maximum temperature and the basic temperature variation coefficient.

[0020] According to another specific embodiment of the present invention, the capacity difference proportional coefficient of the battery in each charging process is determined according to the first capacity difference coefficient, the first voltage difference, the second voltage difference and the change in the first battery state of charge in each charging process, which are respectively recorded as the first capacity difference proportional coefficient and the second capacity difference proportional coefficient, specifically including:

[0021] Determine a first proportional coefficient according to the first capacity difference coefficient and the first voltage difference during each charging process, determine a second proportional coefficient according to the first capacity difference coefficient and the second voltage difference, and determine a third proportional coefficient according to the first capacity difference coefficient and the change in the state of charge of the first battery;

[0022] Determine a first proportional base coefficient corresponding to the first proportional coefficient, a second proportional base coefficient corresponding to the second proportional coefficient, and a third proportional base coefficient corresponding to the third proportional coefficient according to the proportional relationship among the first proportional coefficient, the second proportional coefficient, and the third proportional coefficient in each charging process;

[0023] The first capacity difference proportional coefficient and the second capacity difference proportional coefficient are determined according to the product of the first proportional base coefficient, the second proportional base coefficient and the third proportional base coefficient in each charging process.

[0024] According to another specific embodiment of the present invention, the attenuation degree of the battery capacity difference is evaluated according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient, specifically including:

[0025] The attenuation degree of the battery capacity difference is evaluated according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient and the difference between the first battery state of charge and the second battery state of charge.

[0026] According to another specific embodiment of the present invention, the attenuation degree of the battery capacity difference is evaluated according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient, specifically including:

[0027] Determine a difference ratio between the second capacity difference proportional coefficient and the first capacity difference proportional coefficient;

[0028] The difference ratio indicates the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient, the second capacity difference proportional coefficient is the capacity difference proportional coefficient corresponding to the second charging process during the two charging processes, and the first capacity difference proportional coefficient is the capacity difference proportional coefficient corresponding to the first charging process during the two charging processes;

[0029] The attenuation degree of the battery capacity difference is evaluated based on the difference ratio.

[0030] According to another specific embodiment of the present invention, evaluating the attenuation degree of the battery capacity difference according to the difference ratio specifically includes:

[0031] In the case where the change in the difference between the first battery state of charge and the second battery state of charge during two charging processes does not exceed the first threshold, when the difference ratio does not exceed the first proportional threshold, it indicates that the battery capacity difference is naturally decaying; when the difference ratio exceeds the first proportional threshold and does not exceed the second proportional threshold, it indicates that the battery capacity difference is aggravatedly decayed; when the difference ratio exceeds the second proportional threshold, it indicates that the battery capacity difference is normally decaying;

[0032] When the change amount of the difference between the first battery state of charge and the second battery state of charge during the two charging processes exceeds the first threshold, when the difference ratio is not lower than the third ratio threshold, it indicates that the battery capacity difference is normally attenuated;

[0033] The first ratio threshold value<the second ratio threshold value<the third ratio threshold value, and the first threshold value is a lower limit of a change in a difference between the first battery state of charge and the second battery state of charge when the battery is seriously aged.

[0034] In a second aspect, an embodiment of the present invention discloses a device for evaluating battery capacity difference, wherein the battery is a lithium iron phosphate battery, and the battery includes a plurality of battery cells. The evaluation device includes:

[0035] A parameter acquisition module, used to respectively determine a first voltage difference, a first battery state of charge, a second battery state of charge, a second voltage difference and a change in the first battery state of charge during two charging processes of the battery;

[0036] Among them, the battery can obtain a maximum cell single-cell voltage change curve during each charging process, the maximum cell single-cell voltage change curve is a curve composed of the maximum cell single-cell voltages of all cell single-cells of the battery at multiple moments during the charging process and has a first plateau period and a second plateau period, the first voltage difference is the difference between the maximum cell single-cell voltage and the minimum cell single-cell voltage corresponding to the beginning of the first plateau period of the maximum cell single-cell voltage change curve, the first battery state of charge is the battery state of charge corresponding to the end of the first plateau period of the maximum cell single-cell voltage change curve, the second battery state of charge is the battery state of charge corresponding to the beginning of the second plateau period of the maximum cell single-cell voltage change curve, the second voltage difference is the difference between the maximum cell single-cell voltage and the minimum cell single-cell voltage corresponding to the end of the second plateau period of the maximum cell single-cell voltage change curve, and the first battery state of charge change amount is the change amount of the battery state of charge jump when the maximum cell single-cell voltage of the battery exceeds the battery full voltage threshold during the charging process;

[0037] A capacity difference determination module, used to determine a first capacity difference coefficient of the battery in each charging process according to a difference between a first battery state of charge and a second battery state of charge in each charging process;

[0038] A proportional coefficient determination module, used to determine the capacity difference proportional coefficient of the battery in each charging process according to the first capacity difference coefficient, the first voltage difference, the second voltage difference and the change in the first battery state of charge in each charging process, which are recorded as the first capacity difference proportional coefficient and the second capacity difference proportional coefficient respectively;

[0039] The capacity difference evaluation module is used to evaluate the attenuation degree of the battery capacity difference according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient.

[0040] By adopting the above technical scheme, the battery capacity difference evaluation device of the present invention determines the change amount of the battery state of charge in the time period through the battery state of charge corresponding to the end of the first plateau period and the beginning of the second plateau period of the highest battery cell voltage change curve, so as to determine the battery capacity difference. Since the battery capacity difference does not change during each charging process, the present invention also establishes the capacity difference proportional coefficient of the battery during each charging process by determining the battery capacity difference corresponding to the beginning of the first plateau period and the end of the second plateau period of the highest battery cell voltage change curve, thereby reducing the influence of errors or other influencing factors on the capacity difference calculation, and the change of the capacity difference proportional coefficient during different charging processes can more accurately evaluate the attenuation degree of the battery capacity difference during use.

[0041] In a third aspect, an embodiment of the present invention discloses an electronic device, including a processor and a memory, wherein the memory stores at least one instruction, and when the at least one instruction is executed by the processor, the battery capacity difference evaluation method in any of the aforementioned embodiments is implemented.

[0042] By adopting the above technical solution, the electronic device determines the change amount of the battery state of charge in the time period through the battery state of charge corresponding to the end of the first plateau period and the beginning of the second plateau period of the highest battery cell voltage change curve, so as to determine the battery capacity difference. Since the battery capacity difference does not change during each charging process, the present invention also establishes the capacity difference proportional coefficient of the battery during each charging process by determining the battery capacity difference corresponding to the beginning of the first plateau period and the end of the second plateau period of the highest battery cell voltage change curve, thereby reducing the influence of errors or other influencing factors on the capacity difference calculation, and the change of the capacity difference proportional coefficient during different charging processes can more accurately evaluate the attenuation degree of the battery capacity difference during use.

[0043] In a fourth aspect, an embodiment of the present invention discloses a computer-readable storage medium, in which at least one instruction is stored. When the at least one instruction is executed, the battery capacity difference evaluation method in any of the aforementioned embodiments is implemented.

[0044] By adopting the above technical solution, the computer-readable storage medium can determine the change in the battery state of charge during the time period through the battery state of charge corresponding to the end of the first plateau period and the beginning of the second plateau period of the highest battery cell voltage change curve, so as to determine the battery capacity difference. Since the battery capacity difference does not change during each charging process, the present invention also establishes the capacity difference proportional coefficient of the battery during each charging process by determining the battery capacity difference corresponding to the beginning of the first plateau period and the end of the second plateau period of the highest battery cell voltage change curve, thereby reducing the influence of errors or other influencing factors on the capacity difference calculation, and the change of the capacity difference proportional coefficient during different charging processes can more accurately evaluate the attenuation degree of the battery capacity difference during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram showing the process of the method for evaluating battery capacity difference in an embodiment of the present invention Figure 1 ;

[0046] Figure 2 Schematic diagram showing the process of the method for evaluating battery capacity difference in an embodiment of the present invention Figure 2 ;

[0047] Figure 3 Schematic diagram showing the process of the method for evaluating battery capacity difference in an embodiment of the present invention Figure 3 ;

[0048] Figure 4 Schematic diagram showing the process of the method for evaluating battery capacity difference in an embodiment of the present invention Figure 4 ;

[0049] Figure 5 Schematic diagram showing the process of the method for evaluating battery capacity difference in an embodiment of the present invention Figure 5 ;

[0050] Figure 6 A schematic diagram showing the structure of a device for evaluating battery capacity difference in an embodiment of the present invention;

[0051] Figure 7 A schematic diagram showing the structure of an electronic device in an embodiment of the present invention is shown;

[0052] Figure 8 A schematic diagram showing a maximum cell voltage variation curve and a minimum cell voltage variation curve during charging in an embodiment of the present invention;

[0053] Fig. 9 A schematic diagram showing a curve of a change in the state of charge of a battery during a charging process in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may extend based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0055] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0056] The terms “first”, “second”, etc. are only used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0057] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0058] The inventors carefully studied the prior art and found that the prior art did not fully consider the factors affecting the capacity difference when evaluating the battery capacity difference, nor could it accurately analyze the changing trend of the battery capacity difference during use, making it difficult to accurately predict the later working performance of the battery. The inventors hope to solve the above problems.

[0059] First, refer to Figure 1 The present invention provides a method for evaluating the battery capacity difference. The battery is a lithium iron phosphate battery. The battery includes a plurality of battery cells. The method for evaluating the battery capacity difference includes the following steps:

[0060] S1: respectively determining a first voltage difference, a first battery state of charge, a second battery state of charge, a second voltage difference and a change in the first battery state of charge during two charging processes of the battery.

[0061] Among them, the battery can obtain the highest cell voltage change curve during each charging process. The highest cell voltage change curve is a curve composed of the highest cell voltages of all cell of the battery at multiple moments during the charging process and has a first plateau period and a second plateau period. During each charging process, the voltages of all cell of the battery can be collected in real time, and the highest voltage (i.e., the highest cell voltage) among all cell at each moment can be found, so that the highest cell voltage change curve can be drawn. In addition, during each charging process, after the voltages of all cell of the battery are collected in real time, the lowest voltage (i.e., the lowest cell voltage) among all cell at each moment can also be found, and the lowest cell voltage change curve can be drawn accordingly. Due to its electrochemical characteristics, lithium iron phosphate battery will have a voltage plateau during the charging process. In the process of charging the lithium iron phosphate battery from empty to fully charged, there will be two plateaus, that is, the highest cell voltage change curve has two plateaus, namely the first plateau period and the second plateau period, and the lowest cell voltage change curve also has two plateaus. Reference Figure 8 , Figure 8The maximum cell voltage change curve and the minimum cell voltage change curve are shown. According to the maximum cell voltage change curve, the corresponding time point can be found to determine the maximum cell voltage, the minimum cell voltage or the battery charge state corresponding to the corresponding time point.

[0062] In the first plateau period or the second plateau period, although the battery state of charge will increase, the voltage increases very slowly. It can be considered that the voltage remains basically unchanged, which is not conducive to determining the corresponding battery state of charge according to the voltage value, and the difference between the highest battery cell voltage and the lowest battery cell voltage in the plateau period is very small, and it is difficult to accurately establish the relationship between the battery voltage change and the battery state of charge change. The error will be large, and it is difficult to accurately determine the capacity difference. In addition, the highest battery cell voltage change curve will appear in the plateau period before the lowest battery cell voltage change curve. Therefore, the four time nodes are selected when the highest battery cell voltage change curve determines the beginning of the first plateau period, the end of the first plateau period, the beginning of the second plateau period, and the end of the second plateau period, and then one or more parameters of the highest battery cell voltage, the lowest battery cell voltage, and the battery state of charge are determined according to the above four time nodes, and then the above first voltage difference, the first battery state of charge, the second battery state of charge, the second voltage difference, and the change in the first battery state of charge are obtained, which helps to improve the accuracy of the capacity difference calculation and the accuracy of the capacity difference evaluation.

[0063] More specifically, at the beginning of the first plateau period, the highest cell voltage and the lowest cell voltage at this time are determined, wherein the lowest cell voltage can be directly obtained after detecting the voltages of all cell units and comparing the minimum value, or can be obtained after reading the data at the corresponding time point on the lowest cell voltage change curve. The first voltage difference can be obtained by calculating the difference between the highest cell voltage and the lowest cell voltage corresponding to the beginning of the first plateau period of the highest cell voltage change curve. At the end of the second plateau period, the highest cell voltage and the lowest cell voltage are determined at this time, and the second voltage difference can be obtained by calculating the difference between the highest cell voltage and the lowest cell voltage corresponding to the end of the second plateau period of the highest cell voltage change curve.

[0064] In addition, there is a time period between the first plateau period and the second plateau period of the highest cell voltage change curve when the voltage rises faster than the plateau period. During this time period, the change of the battery state of charge (SOC) can be determined more accurately. Therefore, at the end of the first plateau period of the highest cell voltage change curve, the corresponding battery state of charge is determined to be the first battery state of charge, and at the beginning of the second plateau period of the highest cell voltage change curve, the corresponding battery state of charge is determined to be the second battery state of charge. Among them, the first battery state of charge and the second battery state of charge are the states of charge of the battery, for example, they can be the battery state of charge calculated by taking the average of all battery states of charge of all cell units in the battery.

[0065] When charging a battery, usually when the voltage of one cell exceeds the voltage threshold corresponding to the battery being fully charged, the battery is considered to be fully charged and charging will be stopped. During the charging process, the highest cell voltage will first exceed the battery full voltage threshold. The battery full voltage threshold may be, for example, around 3.65V. When the highest cell voltage exceeds the battery full voltage threshold, even if the battery state of charge (SOC) has not reached 100% at this time, the battery state of charge will be forced to jump to 100%, that is, the battery state of charge will jump, such as Fig. 9 As shown, the charging current will become extremely small at this time, and the highest cell voltage will be prevented from further increasing. The charging circuit will be cut off in time to stop charging to protect the battery. In this embodiment, it is also necessary to determine the change in the battery state of charge when the highest cell voltage of the battery exceeds the first battery state of charge change during the charging process. For example, a curve of the change in the battery state of charge during the charging process can be drawn, such as Fig. 9 ,exist Fig. 9 The time when the battery state of charge jumps is found in the change curve shown, and then the first battery state of charge change amount is determined. For another example, when the battery state of charge jumps, the first battery state of charge change amount can be calculated by calculating how much the battery state of charge rises in a short time, where the short time can be about 2 minutes, for example. If the time is too long, the charging circuit of the battery has not been disconnected, and there may be a risk of overcharging. If the time is too short, it may be difficult to accurately calculate the first battery state of charge change amount.

[0066] S2: Determine a first capacity difference coefficient of the battery in each charging process according to a difference between the first battery state of charge and the second battery state of charge in each charging process.

[0067] Among them, the first capacity difference coefficient is used to reflect the capacity difference of the battery during each charging process. Specifically, the product of the first capacity difference coefficient and the nominal capacity can be calculated to obtain the capacity difference. The nominal capacity can be, for example, the capacity designed when the battery leaves the factory. In this embodiment, it is necessary to understand the relative gap between the first battery state of charge and the second battery state of charge. Even if there is an error when measuring the first battery state of charge and the second battery state of charge, the error can be basically eliminated after subtracting the two. The calculation method is simple and the accuracy is higher. If voltage is selected for calculation, multiple influencing factors such as current and temperature must also be considered. The calculation method is more complicated and the accuracy is lower.

[0068] S3: Determine a capacity difference proportional coefficient of the battery in each charging process according to the first capacity difference coefficient, the first voltage difference, the second voltage difference and the change in the first battery state of charge in each charging process, which are recorded as the first capacity difference proportional coefficient and the second capacity difference proportional coefficient respectively.

[0069] Among them, since the battery capacity difference does not change during one charging process, and the capacity difference can be determined based on the product of the capacity difference coefficient and the nominal capacity, the nominal capacity of a battery will not change during use, so the capacity difference coefficient of the battery will not change during one charging process. Therefore, the first capacity difference coefficient can be used as a reference to determine the capacity difference coefficient at other times during the entire charging process, and then combined with the first capacity difference coefficient, the first voltage difference, the second voltage difference and the change in the first battery state of charge, the capacity difference proportional coefficient in each charging process can be determined. The capacity difference proportional coefficients corresponding to the two charging processes can be the first capacity difference proportional coefficient and the second capacity difference proportional coefficient, respectively.

[0070] By only determining the first capacity difference coefficient and determining the capacity difference proportional coefficient based on the first capacity difference coefficient, there is no need to directly calculate the capacity difference, which helps to simplify the calculation and can also ensure the accuracy of the determined capacity difference proportional coefficient.

[0071] Furthermore, in other embodiments, the capacity difference of the battery during each charging process can be determined according to the difference between the first battery state of charge and the second battery state of charge, and the capacity difference proportional coefficient can be determined according to the capacity difference, the first voltage difference, the second voltage difference and the change in the first battery state of charge.

[0072] S4: Evaluate the attenuation degree of the battery capacity difference according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient.

[0073] Among them, according to the difference in the capacity difference proportional coefficients of the two charging processes, that is, the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient, the attenuation degree of the battery capacity difference can be more accurately evaluated and the capacity difference attenuation trend can be understood.

[0074] By adopting the above technical scheme, the battery capacity difference evaluation method of the present invention determines the change amount of the battery state of charge in the time period through the battery state of charge corresponding to the end of the first plateau period and the beginning of the second plateau period of the highest battery cell voltage change curve, so as to determine the battery capacity difference. Since the battery capacity difference does not change during each charging process, the present invention also establishes the capacity difference proportional coefficient of the battery during each charging process by determining the battery capacity difference corresponding to the beginning of the first plateau period and the end of the second plateau period of the highest battery cell voltage change curve, thereby reducing the influence of errors or other influencing factors on the capacity difference calculation, and the change of the capacity difference proportional coefficient during different charging processes can more accurately evaluate the attenuation degree of the battery capacity difference during use.

[0075] Further, refer to Figure 2 , step S2 in the aforementioned embodiment further includes the following steps:

[0076] S21: Determine the temperature variation coefficient from the end of the first plateau period to the beginning of the second plateau period of the maximum cell voltage variation curve during each charging process.

[0077] The temperature variation coefficient is used to indicate the degree of change of the battery temperature with the maximum battery cell voltage from the end of the first plateau period to the beginning of the second plateau period.

[0078] S22: Determine a first capacity difference coefficient of the battery in each charging process according to the temperature variation coefficient in each charging process and the difference between the first battery state of charge and the second battery state of charge.

[0079] The first capacity difference coefficient can be calculated using the following formula 1 and formula 2:

[0080] ΔQ=ΔSOC2*t(Formula 1)

[0081] ΔSOC2=SOC3-SOC2 (Formula 2)

[0082] Wherein, ΔQ is the first capacity difference coefficient, SOC2 is the first battery state of charge, SOC3 is the second battery state of charge, ΔSOC2 is the difference between the first battery state of charge SOC2 and the second battery state of charge SOC3, and t is the temperature variation coefficient.

[0083] Since the temperature of the battery will rise during the charging process, and the duration from the end of the first plateau period to the beginning of the second plateau period is relatively long, which can last about ten minutes or even dozens of minutes, the temperature changes significantly, which will have a greater impact on the capacity difference, that is, it will have a greater impact on the capacity difference coefficient, which cannot be ignored. By introducing the temperature variation coefficient, the influence of temperature on the calculation of the battery capacity difference can be fully considered, and the accuracy of the calculation of the first capacity difference coefficient can be further improved.

[0084] Further, refer to Figure 3 In the above embodiment, step S21 further includes the following steps:

[0085] S211: Determine the first minimum temperature of all battery cells in the battery corresponding to the end of the first plateau of the maximum battery cell voltage variation curve during each charging process, and the second maximum temperature of all battery cells in the battery corresponding to the beginning of the second plateau.

[0086] Among them, multiple temperature sensors may be provided in the battery, and the temperature sensors are used to measure the temperature of the battery cells in the battery. Exemplarily, in the battery, the ratio of the number of battery cells to the number of temperature sensors may be 3:1 to 4:1. During the entire charging process, the temperature sensor measures the temperature of the battery cells. At the end of the first plateau period, the minimum temperature among the temperatures measured by the multiple temperature sensors is the first minimum temperature. At the beginning of the second plateau period, the maximum temperature among the temperatures measured by the multiple temperature sensors is the second maximum temperature.

[0087] S212: Determine a basic temperature variation coefficient according to a variation of the maximum battery cell voltage with the battery temperature in a first plateau period of the maximum battery cell voltage variation curve.

[0088] Among them, the first plateau period in the maximum battery cell voltage change curve lasts for a long time, the temperature changes significantly, the voltage increases slowly, and it is in the period when the battery just starts to charge. At this time, the battery temperature is still relatively low, which is conducive to more accurate and rapid determination of the battery's basic temperature variation coefficient. The basic temperature variation coefficient can be used to indicate the change of the maximum battery cell voltage with the battery temperature. The basic temperature variation coefficient can be determined more specifically based on the temperature change during the battery charging process. Different types of batteries have different basic temperature variation coefficients.

[0089] S213: Determine the temperature variation coefficient according to the difference between the first lowest temperature and the second highest temperature and the basic temperature variation coefficient.

[0090] The temperature variation coefficient can be determined by the following formula 3:

[0091] t=(T MAX -T MIN )*d(Formula 3)

[0092] Where t is the temperature variation coefficient, T MAX is the second highest temperature, T MIN is the first minimum temperature, and d is the basic temperature variation coefficient.

[0093] By adopting the above method, the relationship between the battery temperature change and the voltage increase from the end of the first plateau period to the beginning of the second plateau period of the highest cell voltage change curve during charging can be accurately determined, thereby facilitating accurate calculation of the battery capacity difference.

[0094] Further, refer to Figure 4 In the above embodiments, step S3 further includes the following steps:

[0095] S31: determining a first proportional coefficient according to the first capacity difference coefficient and the first voltage difference during each charging process, determining a second proportional coefficient according to the first capacity difference coefficient and the second voltage difference, and determining a third proportional coefficient according to the first capacity difference coefficient and the change in the first battery state of charge.

[0096] Specifically, the first proportional coefficient, the second proportional coefficient, and the third proportional coefficient may be determined according to the following Formula 4, Formula 5, and Formula 6:

[0097] ΔU1=U1max-U1min (Formula 4)

[0098] ΔU4=U4max-U4min (Formula 5)

[0099] ΔQ=ΔSOC2*t=A*ΔU1=B*ΔSOC5=C*ΔU4 (Formula 6)

[0100] Among them, U1max is the highest cell voltage corresponding to the beginning of the first plateau period of the highest cell voltage change curve, U1min is the lowest cell voltage corresponding to the beginning of the first plateau period of the highest cell voltage change curve, ΔU1 is the first voltage difference, U4max is the highest cell voltage corresponding to the end of the second plateau period of the highest cell voltage change curve, U4min is the lowest cell voltage corresponding to the end of the second plateau period of the highest cell voltage change curve, ΔU4 is the second voltage difference, ΔSOC5 is the change in the first battery state of charge, ΔQ is the first capacity difference coefficient, t is the temperature change coefficient, ΔSOC2 is the difference between the first battery state of charge SOC2 and the second battery state of charge SOC3, A is the first proportional coefficient, B is the second proportional coefficient, and C is the third proportional coefficient.

[0101] S32: Determine a first proportional base coefficient corresponding to the first proportional coefficient, a second proportional base coefficient corresponding to the second proportional coefficient, and a third proportional base coefficient corresponding to the third proportional coefficient according to the proportional relationship among the first proportional coefficient, the second proportional coefficient, and the third proportional coefficient in each charging process.

[0102] After determining the first proportional coefficient A, the second proportional coefficient B, and the third proportional coefficient C through the above formula 6, the proportional relationship between the three can be obtained accordingly, and then the first proportional base coefficient a corresponding to the first proportional coefficient A, the second proportional base coefficient b corresponding to the second proportional coefficient B, and the third proportional base coefficient c corresponding to the third proportional coefficient C can be determined according to the proportional relationship between the three. Exemplarily, when A is 6, B is 4, and C is 2, the proportional relationship between the three is A:B:C=3:2:1, at this time a can be 3, b can be 2, and c can be 1.

[0103] In other embodiments, there is no need to directly calculate the specific values ​​of the first proportional coefficient A, the second proportional coefficient B, and the third proportional coefficient C. It is only necessary to determine the proportional relationship between the first proportional coefficient A, the second proportional coefficient B, and the third proportional coefficient C through Formula 6, and then obtain the corresponding basic proportional coefficients a, b, and c of the three, which can simplify the calculation.

[0104] S33: determining a first capacity difference proportional coefficient and a second capacity difference proportional coefficient according to the product of the first proportional base coefficient, the second proportional base coefficient and the third proportional base coefficient in each charging process.

[0105] Among them, in this embodiment, taking the first charging process of the two charging processes as the first proportional basic coefficient a1, the second proportional basic coefficient b1, the third proportional basic coefficient c1, and the second charging process as the first proportional basic coefficient a2, the second proportional basic coefficient b2, and the third proportional basic coefficient c2 as an example, the first capacity difference proportional coefficient D1 is a1*b1*c1, and the second capacity difference proportional coefficient D2 is a2*b2*c2.

[0106] Further, in the above embodiments, step S4 may include the following steps: evaluating the attenuation degree of the battery capacity difference according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient and the difference between the first battery state of charge and the second battery state of charge.

[0107] Specifically, the difference between the first battery state of charge and the second battery state of charge can reflect the degree of battery aging. When the battery aging is serious (for example, long battery usage time will cause serious battery aging), a looser evaluation standard can be set to evaluate the attenuation degree of the battery capacity difference. When the battery aging is not serious (for example, the battery is in short use and the battery is a new battery), at this time, a stricter evaluation standard can be set to evaluate the attenuation degree of the battery capacity difference. By comprehensively considering the degree of battery aging and the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient, different evaluation standards are set in a targeted manner, which can further improve the accuracy of the evaluation of the battery capacity difference attenuation degree, ensure the use of the battery, and promptly repair or replace the battery when an abnormality is found.

[0108] Further, refer to Figure 5 In the above embodiments, step S4 may further include the following steps:

[0109] S41: Determine a difference ratio between the second capacity difference proportional coefficient and the first capacity difference proportional coefficient.

[0110] The difference ratio indicates the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient, the second capacity difference proportional coefficient is the capacity difference proportional coefficient corresponding to the second charging process in the two charging processes, and the first capacity difference proportional coefficient is the capacity difference proportional coefficient corresponding to the first charging process in the two charging processes. Specifically, in this embodiment, the difference ratio may be, for example, D2 / D1, that is, (a2*b2*c2) / (a1*b1*c1).

[0111] S42: Evaluate the attenuation degree of the battery capacity difference according to the difference ratio.

[0112] When the change in the difference between the first battery state of charge and the second battery state of charge during two charging processes does not exceed the first threshold: when the difference ratio does not exceed the first proportional threshold, it indicates that the battery capacity difference decays naturally; when the difference ratio exceeds the first proportional threshold and does not exceed the second proportional threshold, it indicates that the battery capacity difference decays aggravatedly; when the difference ratio exceeds the second proportional threshold, it indicates that the battery capacity difference decays normally.

[0113] When the change in the difference between the first battery state of charge and the second battery state of charge during two charging processes exceeds the first threshold value: when the difference ratio is not lower than the third ratio threshold value, it indicates that the battery capacity difference is normally attenuated.

[0114] The first ratio threshold value<the second ratio threshold value<the third ratio threshold value, and the first threshold value is a lower limit of a change in a difference between the first battery state of charge and the second battery state of charge when the battery is seriously aged.

[0115] In addition, when the change in the difference between the first battery state of charge and the second battery state of charge during the two charging processes exceeds the first threshold, when the difference ratio is lower than the third ratio threshold, it indicates that the battery capacity difference is naturally attenuated.

[0116] For example, a standard battery state of charge ΔSOC0 is set at the factory. Based on ΔSOC0, the change of ΔSOC2 relative to ΔSOC0 during the two charging processes can be calculated respectively, and then the change of ΔSOC2 during the two charging processes can be obtained. In one embodiment, when the change of ΔSOC2 does not exceed the first threshold, it can be considered that the aging degree of the battery is not serious; when the change of ΔSOC2 exceeds the first threshold, it can be considered that the aging degree of the battery is serious. In another embodiment, when the change of ΔSOC2 is lower than the first threshold, it can be considered that the aging degree of the battery is not serious; when the change of ΔSOC2 is not lower than the first threshold, it can be considered that the aging degree of the battery is serious. For example, the change of ΔSOC2 relative to ΔSOC0 and the change of ΔSOC2 during the two charging processes can be expressed in percentages, and the first threshold can be set to 10-15% accordingly. In other embodiments, the change of ΔSOC2 relative to ΔSOC0 and the change of ΔSOC2 during the two charging processes can also be expressed in other forms, and the first threshold can also be expressed in other forms accordingly, which can be adjusted according to actual conditions. The value of the first threshold value may also be changed according to actual conditions, as long as it can reflect the aging degree of the battery.

[0117] Furthermore, for batteries whose ΔSOC2 variation exceeds the first threshold value during the two charging processes, i.e., severely aged batteries, more attention needs to be paid so that the batteries can be repaired or replaced in time to improve safety. Batteries whose battery capacity difference is often attenuated also need to be paid more attention so that they can be maintained and processed in time to improve safety.

[0118] In addition, the first ratio threshold, the second ratio threshold and the third ratio threshold can also be determined according to actual conditions. Specifically, the historical data of the use of lithium iron phosphate batteries can be paid attention to, and the data of natural attenuation, aggravated attenuation and abnormal attenuation of battery capacity difference can be found out according to the historical data, and the corresponding data changes can be observed to determine the first ratio threshold, the second ratio threshold and the third ratio threshold.

[0119] Exemplarily, the difference between the first battery state of charge and the second battery state of charge is ΔSOC2, and the difference ratio is (a2*b2*c2) / (a1*b1*c1). The first ratio threshold may be, for example, 1.1-1.3, the second ratio threshold may be, for example, 1.46-1.55, and the third ratio threshold may be, for example, 1.76-1.83.

[0120] In a more specific embodiment, when the change in ΔSOC2 does not exceed 15%, when (a2*b2*c2) / (a1*b1*c1)≤1.2, the battery capacity difference is considered to be naturally decaying; when 1.2<(a2*b2*c2) / (a1*b1*c1)≤1.5, the battery capacity difference is considered to be aggravated by decay; when (a2*b2*c2) / (a1*b1*c1)>1.5, the battery capacity difference is considered to be normally decaying.

[0121] When the change in ΔSOC2 exceeds 15%, when (a2*b2*c2) / (a1*b1*c1)≥1.8, the capacity difference is considered to be normally decaying; when (a2*b2*c2) / (a1*b1*c1)<1.8, the capacity difference is considered to be naturally decaying.

[0122] By adopting the above method, by establishing a proportional relationship between different parameters in each charging process, and then determining the capacity difference proportional coefficient corresponding to each charging process, and then evaluating the battery capacity difference attenuation degree according to the ratio of the capacity difference coefficients of the two charging processes, it is helpful to establish a standardized measurement, eliminate the influence of errors or deviations that may exist in different charging processes, understand the relative change of capacity difference, and reduce the amount of calculation. There is no need to actually calculate the size of the capacity difference, and the accurate determination of the proportional coefficient will not be affected by the error in the capacity difference calculation. It can simplify data analysis and help improve the accuracy of the evaluation of the battery capacity difference attenuation degree.

[0123] Furthermore, in each of the above embodiments, the two charging processes are two adjacent charging processes for fully charging the battery. More specifically, each charging process can be a process from a dead battery state to a fully charged state after the battery is fully discharged. The battery can be, for example, a battery for a new energy vehicle. In actual use, users usually charge the battery once every 2-7 days, and the time interval between the two charging processes can be, for example, 2-7 days. More specifically, the time interval can be, for example, 7 days. By detecting the capacity difference proportional coefficient of each of the two charging processes, and then determining the change in the capacity difference proportional coefficient, it is helpful to monitor the attenuation degree of the battery capacity difference during use.

[0124] When the two charging processes are adjacent and the time interval between the two charging processes is 2-7 days, the battery capacity difference can be evaluated in time to determine whether the battery capacity difference has abnormal attenuation. When the battery capacity difference is found to have abnormal attenuation, it is considered that there is a capacity difference safety risk in the battery, so that an early warning can be issued in advance to remind users or relevant maintenance personnel to deal with it in time, for example, the capacity difference percentage can be reduced, the capacity difference can be suppressed from increasing, or batteries with hidden dangers of capacity difference can be eliminated.

[0125] In other embodiments, the capacity difference of lithium iron phosphate batteries used in different products can be evaluated to obtain the capacity difference proportional coefficients of the lithium iron phosphate batteries corresponding to different products during the charging process, and then the capacity difference proportional coefficients can be sorted. For example, based on the sorting results, about 10% of products with relatively poor quality can be identified for key attention analysis and tracking to prevent abnormalities, thereby being able to focus on after-sales services more specifically, saving labor costs, and improving the accuracy and timeliness of after-sales services.

[0126] The battery capacity difference evaluation method provided by the present invention determines the capacity difference proportional coefficient corresponding to each charging process between two charging processes by combining temperature changes, battery charge state changes and voltage changes, and then evaluates the attenuation degree of the battery capacity difference according to the change of the capacity difference proportional coefficient between the two charging processes, which helps to improve the accuracy of the evaluation.

[0127] Second, reference Figure 6 The embodiment of the present invention discloses a battery capacity difference evaluation device 1. The battery is a lithium iron phosphate battery, and the battery includes a plurality of battery cells. The battery capacity difference evaluation device 1 includes a parameter acquisition module 11, a capacity difference determination module 12, a proportional coefficient determination module 13 and a capacity difference evaluation module 14.

[0128] The parameter acquisition module 11 is connected to the capacity difference determination module 12 , the capacity difference determination module 12 is connected to the proportionality coefficient determination module 13 , and the proportionality coefficient determination module 13 is connected to the capacity difference evaluation module 14 .

[0129] Continue to refer Figure 6 The parameter acquisition module 11 is used to respectively determine the first voltage difference, the first battery state of charge, the second battery state of charge, the second voltage difference and the change in the first battery state of charge during two charging processes of the battery.

[0130] Among them, the battery can obtain a maximum cell voltage change curve during each charging process. The maximum cell voltage change curve is a curve composed of the maximum cell voltages of all cell units of the battery at multiple moments during the charging process and has a first plateau period and a second plateau period. The first voltage difference is the difference between the maximum cell voltage and the minimum cell voltage corresponding to the beginning of the first plateau period of the maximum cell voltage change curve. The first battery state of charge is the battery state of charge corresponding to the end of the first plateau period of the maximum cell voltage change curve. The second battery state of charge is the battery state of charge corresponding to the beginning of the second plateau period of the maximum cell voltage change curve. The second voltage difference is the difference between the maximum cell voltage and the minimum cell voltage corresponding to the end of the second plateau period of the maximum cell voltage change curve. The change amount of the first battery state of charge is the change amount of the battery state of charge jump when the maximum cell voltage of the battery exceeds the battery full voltage threshold during the charging process.

[0131] The capacity difference determination module 12 is used to determine a first capacity difference coefficient of the battery in each charging process according to a difference between a first battery state of charge and a second battery state of charge in each charging process.

[0132] The proportional coefficient determination module 13 is used to determine the capacity difference proportional coefficient of the battery in each charging process according to the first capacity difference coefficient, the first voltage difference, the second voltage difference and the change in the first battery state of charge in each charging process, which are recorded as the first capacity difference proportional coefficient and the second capacity difference proportional coefficient respectively.

[0133] The capacity difference evaluation module 14 is used to evaluate the attenuation degree of the battery capacity difference according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient.

[0134] By adopting the above technical scheme, the battery capacity difference evaluation device 1 of the present invention determines the change amount of the battery state of charge in the time period through the battery state of charge corresponding to the end of the first plateau period and the beginning of the second plateau period of the highest battery cell voltage change curve, so as to determine the battery capacity difference. Since the battery capacity difference does not change during each charging process, the present invention also establishes the capacity difference proportional coefficient of the battery during each charging process by determining the battery capacity difference corresponding to the beginning of the first plateau period and the end of the second plateau period of the highest battery cell voltage change curve, thereby reducing the influence of errors or other influencing factors on the capacity difference calculation, and the attenuation degree of the battery capacity difference during use can be more accurately evaluated through the change of the capacity difference proportional coefficient in different charging processes.

[0135] Furthermore, the capacity difference determination module 12 is also used to execute steps S21, S22, S211, S212 and S213 and related steps in the aforementioned embodiment. The proportional coefficient determination module 13 is also used to execute steps S31, S32 and S33 and related steps in the aforementioned embodiment. The capacity difference evaluation module 14 is also used to execute steps S41 and S42 and related steps in the aforementioned embodiment.

[0136] Thirdly, reference Figure 7 The embodiment of the present invention discloses an electronic device 2, including a processor 22 and a memory 21, wherein the memory 21 stores at least one instruction, and when the at least one instruction is executed by the processor 22, the battery capacity difference evaluation method in any of the above embodiments is implemented. The memory 21 may include, for example, a system memory, a fixed non-volatile storage medium, etc. The system memory may store, for example, an operating system, an application program, a boot loader (BootLoader), and other programs.

[0137] By adopting the above technical solution, the electronic device 2 determines the change amount of the battery state of charge in the time period through the battery state of charge corresponding to the end of the first plateau period and the beginning of the second plateau period of the highest battery cell voltage change curve, so as to determine the battery capacity difference. Since the battery capacity difference does not change during each charging process, the present invention also establishes the capacity difference proportional coefficient of the battery during each charging process by determining the battery capacity difference corresponding to the beginning of the first plateau period and the end of the second plateau period of the highest battery cell voltage change curve, thereby reducing the influence of errors or other influencing factors on the capacity difference calculation, and the change of the capacity difference proportional coefficient during different charging processes can more accurately evaluate the attenuation degree of the battery capacity difference during use.

[0138] In a fourth aspect, an embodiment of the present invention discloses a computer-readable storage medium, in which at least one instruction is stored. When the at least one instruction is executed, the battery capacity difference evaluation method in any of the aforementioned embodiments is implemented.

[0139] By adopting the above technical solution, the computer-readable storage medium can determine the change in the battery state of charge during the time period through the battery state of charge corresponding to the end of the first plateau period and the beginning of the second plateau period of the highest battery cell voltage change curve, so as to determine the battery capacity difference. Since the battery capacity difference does not change during each charging process, the present invention also establishes the capacity difference proportional coefficient of the battery during each charging process by determining the battery capacity difference corresponding to the beginning of the first plateau period and the end of the second plateau period of the highest battery cell voltage change curve, thereby reducing the influence of errors or other influencing factors on the capacity difference calculation, and the change of the capacity difference proportional coefficient during different charging processes can more accurately evaluate the attenuation degree of the battery capacity difference during use.

[0140] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable non-transient storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0141] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0142] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0143] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0144] Although the present invention has been illustrated and described with reference to certain preferred embodiments of the present invention, it should be understood by those skilled in the art that the above is a further detailed description of the present invention in conjunction with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. Those skilled in the art may make various changes in form and details, including making several simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A method for evaluating battery capacity difference, characterized in that: The battery is a lithium iron phosphate battery, the battery includes a plurality of battery cells, and the evaluation method includes: Respectively determining a first voltage difference, a first battery state of charge, a second battery state of charge, a second voltage difference and a change in the first battery state of charge of the battery during two charging processes; Wherein, the battery can obtain a maximum cell voltage change curve during each charging process, the maximum cell voltage change curve is a curve composed of the maximum cell voltages of all cell monomers of the battery at multiple moments during the charging process and has a first plateau period and a second plateau period, the first voltage difference is the difference between the maximum cell voltage and the minimum cell voltage corresponding to the beginning of the first plateau period of the maximum cell voltage change curve, the first battery state of charge is the battery state of charge corresponding to the end of the first plateau period of the maximum cell voltage change curve, the second battery state of charge is the battery state of charge corresponding to the beginning of the second plateau period of the maximum cell voltage change curve, the second voltage difference is the difference between the maximum cell voltage and the minimum cell voltage corresponding to the end of the second plateau period of the maximum cell voltage change curve, and the first battery state of charge change amount is the change amount of the battery state of charge jump when the maximum cell voltage of the battery exceeds the battery full voltage threshold during the charging process; Determine a first capacity difference coefficient of the battery in each charging process according to a difference between the first battery state of charge and the second battery state of charge in each charging process; Wherein, the first capacity difference coefficient is used to reflect the capacity difference of the battery during each charging process; Determine a capacity difference proportional coefficient of the battery in each charging process according to the first capacity difference coefficient, the first voltage difference, the second voltage difference and the first battery state of charge change in each charging process, which are recorded as a first capacity difference proportional coefficient and a second capacity difference proportional coefficient respectively; The attenuation degree of the battery capacity difference is evaluated according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient.

2. The method for evaluating battery capacity difference according to claim 1, wherein: Determining a first capacity difference coefficient of the battery in each charging process according to a difference between the first battery state of charge and the second battery state of charge in each charging process specifically includes: Determine the temperature variation coefficient of the maximum battery cell voltage variation curve from the end of the first plateau period to the beginning of the second plateau period during each charging process; the temperature variation coefficient is used to indicate the degree of change of the battery temperature with the maximum battery cell voltage from the end of the first plateau period to the beginning of the second plateau period; The first capacity difference coefficient of the battery in each charging process is determined according to the temperature variation coefficient in each charging process and the difference between the first battery state of charge and the second battery state of charge.

3. The method for evaluating battery capacity difference according to claim 2, wherein: The determining of the temperature variation coefficient from the end of the first plateau period to the beginning of the second plateau period of the maximum cell voltage variation curve during each charging process specifically includes: Determine the first minimum temperature of all the battery cells in the battery corresponding to the end of the first plateau period of the maximum battery cell voltage change curve during each charging process, and the second maximum temperature of all the battery cells in the battery corresponding to the beginning of the second plateau period; Determine a basic temperature variation coefficient according to a variation of the maximum battery cell voltage with the battery temperature in the first plateau period of the maximum battery cell voltage variation curve; The temperature variation coefficient is determined according to a difference between the first minimum temperature and the second maximum temperature and the basic temperature variation coefficient.

4. The method for evaluating battery capacity difference according to claim 1, wherein: The method of determining the capacity difference proportional coefficient of the battery in each charging process according to the first capacity difference coefficient, the first voltage difference, the second voltage difference and the first battery state of charge change in each charging process, which are respectively recorded as the first capacity difference proportional coefficient and the second capacity difference proportional coefficient, specifically includes: Determine a first proportional coefficient according to the first capacity difference coefficient and the first voltage difference in each charging process, determine a second proportional coefficient according to the first capacity difference coefficient and the second voltage difference, and determine a third proportional coefficient according to the first capacity difference coefficient and the change in the first battery state of charge; Determine a first proportional base coefficient corresponding to the first proportional coefficient, a second proportional base coefficient corresponding to the second proportional coefficient, and a third proportional base coefficient corresponding to the third proportional coefficient according to a proportional relationship among the first proportional coefficient, the second proportional coefficient, and the third proportional coefficient in each charging process; The first capacity difference proportional coefficient and the second capacity difference proportional coefficient are determined according to the product of the first proportional base coefficient, the second proportional base coefficient and the third proportional base coefficient in each charging process.

5. The method for evaluating battery capacity difference according to claim 1, wherein: The evaluating the attenuation degree of the battery capacity difference according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient specifically includes: The attenuation degree of the battery capacity difference is evaluated according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient and the difference between the first battery state of charge and the second battery state of charge.

6. The method for evaluating battery capacity difference according to claim 1, wherein: The evaluating the attenuation degree of the battery capacity difference according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient specifically includes: Determine a difference ratio between the second capacity difference proportional coefficient and the first capacity difference proportional coefficient; The difference ratio indicates the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient, the second capacity difference proportional coefficient is the capacity difference proportional coefficient corresponding to the second charging process during the two charging processes, and the first capacity difference proportional coefficient is the capacity difference proportional coefficient corresponding to the first charging process during the two charging processes; The attenuation degree of the battery capacity difference is evaluated according to the difference ratio.

7. The method for evaluating battery capacity difference according to claim 6, wherein: The step of evaluating the attenuation degree of the battery capacity difference according to the difference ratio specifically includes: In the case where the change in the difference between the first battery state of charge and the second battery state of charge during two charging processes does not exceed a first threshold, when the difference ratio does not exceed a first proportional threshold, it indicates that the battery capacity difference is naturally decayed; when the difference ratio exceeds the first proportional threshold and does not exceed a second proportional threshold, it indicates that the battery capacity difference is aggravatedly decayed; when the difference ratio exceeds the second proportional threshold, it indicates that the battery capacity difference is normally decayed; When the change in the difference between the first battery state of charge and the second battery state of charge during two charging processes exceeds the first threshold, when the difference ratio is not lower than a third ratio threshold, it indicates that the battery capacity difference is normally attenuated; Among them, the first ratio threshold<the second ratio threshold<the third ratio threshold, and the first threshold is the lower limit of the change in the difference between the first battery state of charge and the second battery state of charge when the battery is seriously aged.

8. A device for evaluating battery capacity difference, characterized in that: The battery is a lithium iron phosphate battery, the battery includes a plurality of battery cells, and the evaluation device includes: a parameter acquisition module, used to respectively determine a first voltage difference, a first battery state of charge, a second battery state of charge, a second voltage difference and a change in the first battery state of charge of the battery during two charging processes; Wherein, the battery can obtain a maximum cell voltage change curve during each charging process, the maximum cell voltage change curve is a curve composed of the maximum cell voltages of all cell monomers of the battery at multiple moments during the charging process and has a first plateau period and a second plateau period, the first voltage difference is the difference between the maximum cell voltage and the minimum cell voltage corresponding to the beginning of the first plateau period of the maximum cell voltage change curve, the first battery state of charge is the battery state of charge corresponding to the end of the first plateau period of the maximum cell voltage change curve, the second battery state of charge is the battery state of charge corresponding to the beginning of the second plateau period of the maximum cell voltage change curve, the second voltage difference is the difference between the maximum cell voltage and the minimum cell voltage corresponding to the end of the second plateau period of the maximum cell voltage change curve, and the first battery state of charge change amount is the change amount of the battery state of charge jump when the maximum cell voltage of the battery exceeds the battery full voltage threshold during the charging process; a capacity difference determination module, configured to determine a first capacity difference coefficient of the battery in each charging process according to a difference between the first battery state of charge and the second battery state of charge in each charging process; Wherein, the first capacity difference coefficient is used to reflect the capacity difference of the battery during each charging process; a proportional coefficient determination module, configured to determine the capacity difference proportional coefficient of the battery in each charging process according to the first capacity difference coefficient, the first voltage difference, the second voltage difference and the first battery state of charge change in each charging process, which are recorded as the first capacity difference proportional coefficient and the second capacity difference proportional coefficient respectively; The capacity difference evaluation module is used to evaluate the attenuation degree of the battery capacity difference according to the difference between the first capacity difference proportional coefficient and the second capacity difference proportional coefficient.

9. An electronic device, characterized in that: The electronic device includes a processor and a memory, wherein the memory stores at least one instruction, and when the at least one instruction is executed by the processor, the battery capacity difference assessment method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed, the battery capacity difference evaluation method according to any one of claims 1 to 7 is implemented.

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