Battery pack health state evaluation method and device based on fuzzy comprehensive evaluation

Abstract

The invention provides a battery pack health state evaluation method and device based on fuzzy comprehensive evaluation, and the method comprises the steps: obtaining a factor set and a comment set of battery pack health state evaluation, constructing a comprehensive evaluation matrix, carrying out the fuzzy comprehensive evaluation, and obtaining a comprehensive evaluation result. Wherein the factor set comprises indexes of multiple dimensions, specifically, a cycle index index, a consistency index, a safety reliability index and an energy efficiency index, and the indexes reflect the health state of the battery pack of the energy storage system from different dimensions. In the whole process, evaluation results of different evaluation indexes are obtained based on a comment set, and then the influence of different comments and different evaluation indexes on the comprehensive evaluation results is fully considered by adopting a fuzzy comprehensive evaluation method, so that an accurate battery pack health state evaluation result is obtained.

Description

Technical Field

[0001] The present application relates to the technical field of battery detection, and in particular to a method and device for evaluating the health status of a battery pack based on fuzzy comprehensive evaluation. Background Art

[0002] The backup power supply for power-consuming equipment such as automation terminals and communication equipment in the distribution network generally adopts a battery energy storage system. When a failure occurs in the distribution network, the energy storage system plays an irreplaceable role in ensuring the normal operation of automation terminals and communication equipment. However, the battery of the energy storage system is constantly in a state of charge and discharge, so its service life is not long, and its capacity is easily affected by external environmental factors such as temperature and humidity.

[0003] At present, the health status of the battery pack of the energy storage system is mainly achieved through regular manual testing. However, in actual testing work, the judgment of the health status mainly relies on the long-term experience accumulation of the staff, which is highly subjective. Therefore, the current detection effect of the health status of the battery pack of the energy storage system is not good. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a method and device for evaluating the health status of a battery pack based on fuzzy comprehensive evaluation, so as to solve the problem that the prior art has poor detection effect on the health status of a battery pack of an energy storage system.

[0005] The embodiment of the present application provides a battery pack health status evaluation method based on fuzzy comprehensive evaluation, which can be applied to an energy storage system. The method includes:

[0006] Obtaining a factor set and a comment set for evaluating the health status of a battery pack; the evaluation indicators in the factor set include at least two of a cycle number indicator, a consistency indicator, a safety and reliability indicator, and an energy efficiency indicator; different comments in the comment set reflect different health status levels;

[0007] Based on the factor set and comment set, a comprehensive evaluation matrix is ​​constructed;

[0008] A fuzzy comprehensive evaluation is performed according to the comprehensive evaluation matrix to obtain a comprehensive evaluation result, which is used as the battery pack health status evaluation result.

[0009] In the above technical solution, the factor set and comment set for evaluating the health status of the battery pack are obtained, a comprehensive evaluation matrix is ​​constructed, and a fuzzy comprehensive evaluation is performed to obtain a comprehensive evaluation result. Among them, the factor set includes indicators of multiple dimensions, specifically cycle count indicators, consistency indicators, safety and reliability indicators, and energy efficiency indicators. These indicators reflect the health status of the battery pack of the energy storage system from different dimensions. In the whole process, the evaluation results of different evaluation indicators are obtained based on the comment set, and then the fuzzy comprehensive evaluation method is used to fully consider the influence of different comments and different evaluation indicators on the corresponding comprehensive evaluation results, so as to obtain accurate battery pack health status evaluation results.

[0010] In some optional implementations, a comprehensive evaluation matrix is ​​constructed based on the factor set and the comment set, including:

[0011] Obtaining raw data of the battery pack, and calculating evaluation index values ​​of the evaluation indexes according to the raw data;

[0012] According to the evaluation index value and the set evaluation standard value, determine the membership degree of each evaluation index corresponding to different comments;

[0013] According to the membership degree of each evaluation index corresponding to different comments, a single factor evaluation matrix is ​​obtained;

[0014] The set single factor weight matrix is ​​multiplied by the single factor evaluation matrix to obtain a comprehensive evaluation matrix; wherein the value of each element in the single factor weight matrix reflects the influence of the corresponding evaluation index on the health status evaluation of the battery pack;

[0015] According to the comprehensive evaluation matrix, fuzzy comprehensive evaluation is carried out to obtain comprehensive evaluation results, including:

[0016] The comment with the largest membership value in the comprehensive evaluation matrix is ​​taken as the comprehensive evaluation result.

[0017] In some optional embodiments, the cycle number indicator is used to reflect the health status of the battery pack from the dimension of the number of charge and discharge cycles of the battery pack;

[0018] The cycle number index is determined by the total cycle number at the end of the battery pack life and the cumulative cycle number of the battery pack as of the current moment; wherein the cumulative cycle number of the battery pack as of the current moment is determined by the cumulative discharge capacity or the cumulative charge capacity, and the nominal capacity of the battery pack.

[0019] In the above technical solution, considering that as the number of charge and discharge cycles of the battery pack increases, the actual remaining capacity of the battery pack gradually decays until the battery pack reaches the end of its life and cannot be used any more, this embodiment designs a cycle number indicator to reflect the health status of the battery pack from the dimension of the number of charge and discharge cycles of the battery pack. For example, the indicator value is limited to the interval range of [0,1]. The closer the indicator value is to 0, the closer the actual remaining capacity of the battery pack is to the actual remaining capacity at the end of the battery pack's life. If the indicator value is 1, it means that there is no attenuation loss in the capacity of the battery pack; if the indicator value is 0, it means that the battery capacity has decayed to the capacity at the end of the battery life (for example, 80% of the capacity when the battery is not attenuated).

[0020] Specifically, the cycle number index CYC can be calculated by the following method:

[0021]

[0022] Among them, N EOL N is the total number of cycles at the end of the battery life. now Determined by the cumulative number of cycles of the battery pack up to the current moment. N EOL It can be obtained from the battery cycle life test experiment, generally the cumulative number of cycles corresponding to SOH = 80%;

[0023] N now It can be calculated by the following method:

[0024]

[0025] Among them, C accu C is the cumulative discharge capacity or cumulative charge capacity of the battery pack up to the current moment; n is the nominal capacity of the battery pack, I is the discharge or charge current of the battery pack, and t is the total accumulated time.

[0026] In some optional embodiments, the consistency index is used to reflect the health status of the battery pack from the dimension of voltage consistency between battery cells of the battery pack;

[0027] The consistency index is determined by the total number of battery cells in the battery pack and the number of unique battery cells that have consistency issues as of the current moment;

[0028] Among them, the method for determining whether there is a consistency problem with the battery cell includes:

[0029] Determine whether the difference between the voltage of the battery cell and the average voltage of the battery cell of the battery pack is greater than the standard deviation of the battery cell voltage of the battery pack of a set multiple;

[0030] If the standard deviation is greater than the set multiple, there is a consistency problem with the battery cells.

[0031] In the above technical solution, there are multiple battery packs in the energy storage system, and each battery pack includes multiple battery cells. Whether the voltages of the multiple battery cells in the battery pack are consistent will directly affect the operating efficiency and safety of the battery pack. To this end, this embodiment designs a consistency index to reflect the health status of the battery pack from the dimension of voltage consistency between the battery cells of the battery pack. For example, the value range of the consistency index is limited to the interval [0,1]. The closer the value of the consistency index is to 0, the more battery cells in the battery pack have voltage inconsistency problems, that is, the worse the consistency of the battery pack; if the value of the consistency index is 1, it means that there is no consistency problem in the battery pack; if the value of the consistency index is 0, it means that all the cells in the battery pack have consistency problems, but because the consistency between battery cells is relative to each cell, this situation will not actually occur.

[0032] Specifically, the consistency index COS can be calculated as follows:

[0033]

[0034] Where n is the total number of battery cells in the battery pack, m now It is the total number of unique battery cells with consistency issues as of the current moment.

[0035] The method for determining whether there is a consistency problem with the battery cell is as follows:

[0036] At the same time, when There is a consistency problem when There is no consistency problem when . It is the standard deviation of the voltage of the battery cells in the battery pack; is the average voltage of the battery cells in the battery pack; V i is the voltage of the ith battery cell in the battery pack; n is the total number of battery cells in the battery pack.

[0037] In some optional implementations, the safety reliability index is used to reflect the health status of the battery pack from the dimension of the number of battery pack failures;

[0038] The safety reliability index is determined by the cumulative alarm days of each alarm item up to the current moment and the upper limit of the cumulative alarm days of each alarm item;

[0039] The alarm items include at least one of a battery low temperature alarm, a battery high temperature alarm, a battery overvoltage alarm, a battery undervoltage alarm, and a battery insulation abnormality alarm.

[0040] In the above technical solution, the energy storage system may be affected by various working conditions or internal factors during operation, and various faults may occur. In the energy storage system, fault monitoring is usually performed for each battery pack and a corresponding alarm signal is generated, such as monitoring the battery temperature, voltage, and whether there is arc, short circuit, leakage, etc. of the battery pack, so as to perform low battery temperature alarm, high battery temperature alarm, battery overvoltage alarm, battery undervoltage alarm, and battery insulation abnormality alarm. To this end, the present embodiment designs a safety reliability index to reflect the health status of the battery pack from the dimension of the number of times the battery pack fails. For example, the value of the safety reliability index is limited to the interval range of [0,1]. When the value of the safety reliability index is closer to 0, it means that the battery pack has accumulated more faults and is closer to the set cumulative fault limit, that is, the battery safety reliability is lower; if the value of the safety reliability index is 1, it means that the battery pack has not had any faults; if the value of the safety reliability index is 0, it means that the cumulative number of faults of the battery pack has reached the set upper limit.

[0041] Specifically, the safety reliability index can be calculated by the following method:

[0042] Moreover, when When the value of is greater than 1, let SA equal to 0; SA∈[0,1];

[0043] Among them, d i is the cumulative number of alarm days for the ith alarm item as of the current moment, l i is the upper limit of the cumulative alarm days for the ith alarm item, and p is the total number of alarm items.

[0044] In some optional embodiments, the energy efficiency index is used to reflect the health status of the battery pack from the dimension of the charging and discharging efficiency of the battery pack;

[0045] The energy efficiency index is determined by the discharge energy of the battery pack when discharging from the highest value of the set SOC interval to the lowest value of the set SOC interval, and the charging energy of the battery pack when charging from the lowest value of the set SOC interval to the highest value of the set SOC interval.

[0046] In the above technical solution, considering that the charge and discharge efficiency of the battery pack will gradually decrease as the battery pack ages, this embodiment designs an energy efficiency index to reflect the health status of the battery pack from the dimension of the charge and discharge efficiency of the battery pack. For example, the value range of the energy efficiency index is limited to the interval [0,1]. When the value of the energy efficiency index is closer to 0, the charge and discharge efficiency of the battery pack is lower.

[0047] Specifically, the energy efficiency index can be calculated by the following method:

[0048]

[0049] In the formula, E discharge It is the discharge energy of the battery pack when it discharges from the highest value of the set SOC interval to the lowest value of the set SOC interval under a certain discharge condition; E charge It is the charging energy of the battery pack when the battery pack is charged from the lowest value of the set SOC range to the highest value of the set SOC range under a certain charging condition.

[0050] The embodiment of the present application provides a battery pack health status evaluation device based on fuzzy comprehensive evaluation, comprising:

[0051] An acquisition module is used to acquire a factor set and a comment set for evaluating the health status of a battery pack; the evaluation indicators in the factor set include at least two of a cycle number indicator, a consistency indicator, a safety reliability indicator, and an energy efficiency indicator; different comments in the comment set reflect different health status levels;

[0052] A construction module is used to construct a comprehensive evaluation matrix based on the factor set and the comment set;

[0053] The evaluation module is used to perform fuzzy comprehensive evaluation according to the comprehensive evaluation matrix to obtain a comprehensive evaluation result, and use the comprehensive evaluation result as a battery pack health status evaluation result.

[0054] In the above technical solution, the acquisition module is used to obtain the factor set and comment set for evaluating the health status of the battery pack, the construction module is used to construct a comprehensive evaluation matrix, and the evaluation module is used to perform fuzzy comprehensive evaluation to obtain a comprehensive evaluation result. Among them, the factor set includes indicators of multiple dimensions, specifically cycle number indicators, consistency indicators, safety and reliability indicators, and energy efficiency indicators. These indicators reflect the health status of the battery pack of the energy storage system from different dimensions. The device obtains the evaluation results of different evaluation indicators based on the comment set, and then uses the fuzzy comprehensive evaluation method to fully consider the influence of different comments and different evaluation indicators on the corresponding comprehensive evaluation results, so as to obtain accurate battery pack health status evaluation results.

[0055] In some optional implementations, the building blocks specifically include:

[0056] An evaluation index calculation module is used to obtain the original data of the battery pack and calculate the evaluation index value of the evaluation index according to the original data;

[0057] The membership calculation module is used to determine the membership of each evaluation indicator corresponding to different comments according to the evaluation indicator value and the set evaluation standard value;

[0058] The single factor matrix module is used to obtain the single factor evaluation matrix according to the membership degree of each evaluation indicator corresponding to different comments;

[0059] A comprehensive evaluation matrix module is used to multiply the set single factor weight matrix with the single factor evaluation matrix to obtain a comprehensive evaluation matrix; wherein the value of each element in the single factor weight matrix reflects the influence of the corresponding evaluation index on the health status evaluation of the battery pack;

[0060] The evaluation module is also used to take the comment with the largest membership value in the comprehensive evaluation matrix as the comprehensive evaluation result.

[0061] An electronic device provided in an embodiment of the present application includes: a processor and a memory, wherein the memory stores machine-readable instructions executable by the processor, and when the machine-readable instructions are executed by the processor, any of the above methods is performed.

[0062] An embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, any of the above methods is executed. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0064] Figure 1 A flowchart of a method for evaluating the health status of a battery pack based on fuzzy comprehensive evaluation provided in an embodiment of the present application;

[0065] Figure 2 A functional module diagram of a battery pack health status evaluation device based on fuzzy comprehensive evaluation provided in an embodiment of the present application;

[0066] Figure 3 A possible structural diagram of an electronic device provided in an embodiment of the present application.

[0067] Icons: 1-acquisition module, 2-construction module, 3-evaluation module, 41-processor, 42-memory, 43-communication interface, 44-communication bus. DETAILED DESCRIPTION

[0068] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0069] Please refer to Figure 1 , Figure 1A flow chart of the steps of a battery pack health status evaluation method based on fuzzy comprehensive evaluation provided in an embodiment of the present application, the method can be applied to energy storage systems and other battery pack management systems, such as the battery management system BMS of new energy vehicles. In particular, when applied to energy storage systems, it can simultaneously monitor the health of multiple battery packs in the energy storage system. For example, the management terminal of the battery pack communicates with the server, the original data of the battery pack is collected at the management terminal, the management terminal sends the original data to the server, and the evaluation method of this embodiment is executed in the server. Further, the server can feed back the evaluation results to the management terminal. Among them, the management terminal includes but is not limited to personal computers, laptops, smart phones, tablet computers, Internet of Things devices and portable wearable devices. The Internet of Things devices can be smart speakers, smart TVs, smart air conditioners, smart car-mounted devices, etc. Portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc. The server can be implemented as an independent server or a server cluster consisting of multiple servers.

[0070] The method specifically includes:

[0071] Step 100, obtaining a factor set and a comment set for evaluating the health status of a battery pack; the evaluation indicators in the factor set include at least two of a cycle number indicator, a consistency indicator, a safety reliability indicator, and an energy efficiency indicator; different comments in the comment set reflect different health status levels;

[0072] Step 200: construct a comprehensive evaluation matrix based on the factor set and the comment set;

[0073] Step 300: Perform fuzzy comprehensive evaluation according to the comprehensive evaluation matrix to obtain a comprehensive evaluation result, and use the comprehensive evaluation result as a battery pack health status evaluation result.

[0074] In an embodiment of the present application, a factor set and a comment set for evaluating the health status of the battery pack are obtained, a comprehensive evaluation matrix is ​​constructed, a fuzzy comprehensive evaluation is performed, and a comprehensive evaluation result is obtained. Among them, the factor set includes indicators of multiple dimensions, specifically cycle count indicators, consistency indicators, safety and reliability indicators, and energy efficiency indicators. These indicators reflect the health status of the battery pack of the energy storage system from different dimensions. In the whole process, the evaluation results of different evaluation indicators are obtained based on the comment set, and then the fuzzy comprehensive evaluation method is used to fully consider the influence of different comments and different evaluation indicators on the corresponding comprehensive evaluation results, so as to obtain accurate battery pack health status evaluation results.

[0075] In a specific embodiment, in step 100, the factor set U for evaluating the health status of the battery pack is {cycle number index, consistency index, safety and reliability index, energy efficiency index}, and the corresponding comment set V is {excellent, good, average, poor, bad}, wherein the factor set is the evaluation index for evaluating the health status of the battery, and the comment set is the evaluation result of the health status of the battery.

[0076] In step 200, a comprehensive evaluation matrix is ​​constructed based on the factor set and the comment set, which specifically includes:

[0077] Step 210, obtaining raw data of the battery pack, and calculating evaluation index values ​​of the evaluation indexes according to the raw data;

[0078] The raw data of the battery pack includes the basic parameters of the battery pack to be evaluated, as well as the data generated by the battery management system when detecting the battery pack to be evaluated during operation, specifically including the following data: the nominal capacity of the battery, the cycle life test experimental data of the battery, the total voltage, total current, SOC, temperature of the battery pack, the voltage of each battery cell of the battery pack, and the alarm information of the battery pack, wherein the alarm information of the battery pack includes but is not limited to: battery low temperature alarm, battery high temperature alarm, battery overvoltage alarm, battery undervoltage alarm and battery insulation abnormality alarm, etc.

[0079] Based on the original data, the evaluation index values ​​of the four evaluation indicators, namely, the cycle number index, the consistency index, the safety and reliability index, and the energy efficiency index, are calculated. The calculation of the four evaluation indicators is described in detail below:

[0080] About the calculation method of the cycle number indicator:

[0081] The cycle number indicator is used to reflect the health status of the battery pack from the dimension of the number of charge and discharge cycles of the battery pack; the cycle number indicator is determined by the total number of cycles at the end of the battery pack life and the cumulative number of cycles of the battery pack as of the current moment; wherein, the cumulative number of cycles of the battery pack as of the current moment is determined by the cumulative discharge capacity or the cumulative charge capacity, and the nominal capacity of the battery pack.

[0082] In the embodiment of the present application, considering that as the number of charge and discharge cycles of the battery pack increases, the actual remaining capacity of the battery pack gradually decays until the battery pack reaches the end of its life and cannot be used any more, a cycle number indicator is designed in the present embodiment to reflect the health status of the battery pack from the dimension of the number of charge and discharge cycles of the battery pack. For example, the indicator value is limited to the interval range of [0,1]. The closer the indicator value is to 0, the closer the actual remaining capacity of the battery pack is to the actual remaining capacity at the end of the battery pack's life. If the indicator value is 1, it means that there is no attenuation loss in the capacity of the battery pack; if the indicator value is 0, it means that the battery capacity has decayed to the capacity at the end of the battery life (for example, 80% of the capacity when the battery is not attenuated).

[0083] Specifically, the cycle number index CYC can be calculated by the following method:

[0084]

[0085] Among them, N EOL N is the total number of cycles at the end of the battery life. now Determined by the cumulative number of cycles of the battery pack up to the current moment. N EOL It can be obtained from the battery cycle life test experiment, generally the cumulative number of cycles corresponding to SOH = 80%;

[0086] N now It can be calculated by the following method:

[0087]

[0088] Among them, C accu C is the cumulative discharge capacity or cumulative charge capacity of the battery pack up to the current moment; n is the nominal capacity of the battery pack, I is the discharge or charge current of the battery pack, and t is the total accumulated time.

[0089] About the calculation method of consistency index:

[0090] The consistency index is used to reflect the health status of the battery pack from the dimension of voltage consistency between the battery cells of the battery pack; the consistency index is determined by the total number of battery cells in the battery pack and the number of non-repetitive battery cells that have consistency problems as of the current moment; wherein, the method for determining whether there is a consistency problem with the battery cells includes: determining whether the difference between the voltage of the battery cell and the average voltage of the battery cells of the battery pack is greater than a set multiple of the standard deviation of the battery cell voltage of the battery pack; if it is greater than the set multiple of the standard deviation, then the battery cell has a consistency problem.

[0091] In the embodiment of the present application, there are multiple battery packs in the energy storage system, and each battery pack includes multiple battery cells. Whether the voltages of the multiple battery cells in the battery pack are consistent will directly affect the operating efficiency and safety of the battery pack. To this end, this embodiment designs a consistency index to reflect the health status of the battery pack from the dimension of voltage consistency between the battery cells of the battery pack. For example, the value range of the consistency index is limited to the interval [0,1]. When the index value of the consistency index is closer to 0, the more battery cells in the battery pack have voltage inconsistency problems, that is, the worse the consistency of the battery pack; if the value of the consistency index is 1, it means that there is no consistency problem in the battery pack; if the value of the consistency index is 0, it means that all the cells in the battery pack have consistency problems, but because the consistency between battery cells is relative to each cell, this situation will not actually occur.

[0092] Specifically, the consistency index COS can be calculated as follows:

[0093]

[0094] Where n is the total number of battery cells in the battery pack, m now It is the total number of unique battery cells with consistency issues as of the current moment.

[0095] The method for determining whether there is a consistency problem with the battery cell is:

[0096] At the same time, when There is a consistency problem when There is no consistency problem when . It is the standard deviation of the voltage of the battery cells; is the average voltage of the battery cells in the battery pack; V i is the voltage of the ith battery cell in the battery pack; n is the total number of battery cells in the battery pack.

[0097] Specifically, first, obtain the battery pack operation segment data under a certain working condition, for example, the charging SOC range is [30,80], that is, the battery pack starts charging from an SOC value of 30% until the SOC value reaches 80%, the temperature is 25°C, and the charging current rate is 0.5C. Secondly, the battery cell voltage data at each moment of the charging segment is judged according to the above consistency judgment method. If the total number of time points at which a battery cell is judged to have a consistency problem reaches more than half of the total number of time points in the charging segment, and the battery cell has not had a consistency problem before, it is determined that m now The count is increased by 1.

[0098] When actually obtaining the consistency index, it is necessary to judge and calculate the consistency index when encountering a running segment that meets the determined working conditions.

[0099] About the calculation method of safety and reliability index:

[0100] The safety and reliability index is used to reflect the health status of the battery pack from the dimension of the number of times the battery pack fails; the safety and reliability index is determined by the cumulative alarm days of each alarm item as of the current moment, and the upper limit of the cumulative alarm days of each alarm item; wherein the alarm items include at least one of the battery low temperature alarm, the battery high temperature alarm, the battery overvoltage alarm, the battery undervoltage alarm and the battery insulation abnormality alarm.

[0101] In the embodiment of the present application, the energy storage system may be affected by various working conditions or internal factors during operation, and various faults may occur. In the energy storage system, fault monitoring is usually performed for each battery pack and a corresponding alarm signal is generated, such as monitoring the battery temperature, voltage, and whether there is arc, short circuit, leakage, etc. of the battery pack, so as to perform low battery temperature alarm, high battery temperature alarm, battery overvoltage alarm, battery undervoltage alarm, and battery insulation abnormality alarm. To this end, the present embodiment designs a safety reliability index to reflect the health status of the battery pack from the dimension of the number of times the battery pack fails. For example, the value of the safety reliability index is limited to the interval range of [0,1]. When the value of the safety reliability index is closer to 0, it means that the battery pack has accumulated more faults and is closer to the set cumulative fault limit, that is, the battery safety reliability is lower; if the value of the safety reliability index is 1, it means that the battery pack has not had any faults; if the value of the safety reliability index is 0, it means that the cumulative number of faults of the battery pack has reached the set upper limit.

[0102] Specifically, the safety reliability index can be calculated by the following method:

[0103] Moreover, when When the value of is greater than 1, let SA equal to 0; SA∈[0,1];

[0104] Among them, d i is the cumulative number of alarm days for the ith alarm item as of the current moment, l i is the upper limit of the cumulative alarm days for the i-th alarm item, and p is the total number of alarm items. When , SA=0, it means that the deterioration of health status by this indicator has reached the upper limit.

[0105] Specifically, the battery alarm items include but are not limited to common basic alarm items for batteries, such as battery low temperature alarm, battery high temperature alarm, battery overvoltage alarm, battery undervoltage alarm and battery insulation abnormality alarm.

[0106] Among them, when an alarm item alarms multiple times in a single day, the cumulative alarm days of the alarm item will be increased once and only once; in addition, the upper limit of the cumulative alarm days of each alarm item can be determined according to the severity of the alarm item. The higher the severity, the lower the upper limit can be set.

[0107] Regarding the calculation method of energy efficiency index:

[0108] The energy efficiency index is used to reflect the health status of the battery pack from the dimension of the battery pack's charge and discharge efficiency;

[0109] The energy efficiency index is determined by the discharge energy of the battery pack when discharging from the highest value of the set SOC interval to the lowest value of the set SOC interval, and the charging energy of the battery pack when charging from the lowest value of the set SOC interval to the highest value of the set SOC interval.

[0110] In the embodiment of the present application, taking into account that the charge and discharge efficiency of the battery pack will gradually decrease as the battery pack ages, an energy efficiency index is designed in the present embodiment to reflect the health status of the battery pack from the dimension of the charge and discharge efficiency of the battery pack. For example, the value range of the energy efficiency index is limited to the interval [0,1]. When the value of the energy efficiency index is closer to 0, the charge and discharge efficiency of the battery pack is lower.

[0111] Specifically, the energy efficiency index can be calculated by the following method:

[0112]

[0113] In the formula, E discharge It is the discharge energy of the battery pack when it discharges from the highest value of the set SOC interval to the lowest value of the set SOC interval under a certain discharge condition; E charge It is the charging energy of the battery pack when the battery pack is charged from the lowest value of the set SOC range to the highest value of the set SOC range under a certain charging condition.

[0114] Specifically, considering that the charging and discharging conditions of general energy storage systems are relatively stable, firstly, the battery is taken under a certain discharge condition (for example, the temperature of the discharged battery is 25°C, the discharge current ratio is 0.5C, which is actually determined according to the specific daily operating conditions of the energy storage system), and the discharge segment data when the battery is discharged from the highest value of the set SOC interval to the lowest value of the set SOC interval. Then, the charging segment data when the battery is charged from the lowest value of the set SOC interval to the highest value of the set SOC interval under a certain charging condition (for example, the temperature of the charged battery is 25°C, the charging current ratio is 0.2C, which is actually determined according to the specific daily operating conditions of the energy storage system) is taken. Finally, the discharge energy E is calculated respectively. discharge and charging energy E charce :

[0115] E discharge,chaarge =∫0 t Udt

[0116] Wherein, U is the total voltage of the battery pack during discharge or charge; I is the discharge current or charge current of the battery pack; and t is the total discharge duration or charge duration of the discharge segment or charge segment.

[0117] Among them, it should be noted that: (a) the charging condition and the discharging condition of this embodiment are two charging and discharging conditions with similar operating time. Preferably, the charging condition and the discharging condition are just connected. If the actual operating condition cannot be met, a charging and discharging condition that meets the requirements within one week can be taken; (b) the temperature difference between the charging condition and the discharging condition must be less than 5°C; (c) in addition to setting the SOC range, the corresponding discharge segment data and charging segment data can also be obtained by setting the charging cut-off voltage and the discharging cut-off voltage. The charging cut-off voltage and the discharging cut-off voltage are basic performance parameters of the battery. If they cannot be met in the actual operating condition, they can be adjusted up or down according to the actual situation. Once determined, they will not be changed.

[0118] When actually acquiring the energy efficiency index, it is necessary to calculate the energy efficiency index when encountering a segment that meets the determined charging and discharging operating condition.

[0119] Step 220: Determine the degree of membership of each evaluation indicator corresponding to different comments according to the evaluation indicator value and the set evaluation standard value;

[0120] Specifically, the membership functions of each evaluation index to each level of health status are as follows:

[0121]

[0122] Among them, r i1,i2,i3,i4,i5 are the membership degrees of the ith evaluation index in the health status levels of "poor", "relatively poor", "average", "good", and "excellent"; a i1,i2,i3,i4,i5are the evaluation standard values ​​of the ith evaluation index at the health status levels of "poor", "relatively poor", "average", "good", and "excellent"; x i is the i-th evaluation index value; i∈{1,2,3,4};

[0123] Among them, a i1,i2,i3,i4,i5 The method of determining is: Since x i ∈[0,1], and x i The closer it is to 1, the less the indicator affects the battery health status, and the better the battery health status. Conversely, the closer it is to 0, the worse the battery health status. i1,i2,i3,i4,i5 The value of increases in the interval [0,1]. The evaluation criteria of each specific indicator can be determined according to engineering practice or industry experience, or the expert method can be used to analyze the historical data of the cycle number indicator, consistency indicator, safety and reliability indicator and energy efficiency indicator of the battery pack health status evaluation, and analyze the correlation between the evaluation indicators, and construct the evaluation criteria shown in Table 1:

[0124] Table 1. Evaluation criteria for different health status levels of each evaluation index

[0125]

[0126] Among them, taking the cycle number index as an example to illustrate the meaning of the evaluation standard values ​​of each index in the above table, when the index value is greater than 0.9, it is an "excellent" grade; when the index value is ≤0.9 and greater than 0.8, it is a "good" grade; when the index value is ≤0.8 and greater than 0.7, it is a "general" grade; when the index value is ≤0.7 and greater than 0.6, it is a "poor" grade; when the index value is ≤0.6, it is a "bad" grade.

[0127] According to the evaluation index value and the evaluation standard value, the membership degree of each evaluation index corresponding to different comments is determined.

[0128] Step 230, obtaining a single factor evaluation matrix according to the degree of membership of each evaluation indicator corresponding to different comments;

[0129] Specifically, the single factor evaluation matrix R is:

[0130]

[0131] Assume that the evaluation index values ​​calculated at the current moment are: x1 = 0.94, x2 = 0.92, x3 = 0.97, x4 = 0.97, according to the a determined in the above example i1,i2,i3,i4,i5 , then

[0132]

[0133] Step 240: multiply the set single factor weight matrix and the single factor evaluation matrix to obtain a comprehensive evaluation matrix; wherein the value of each element in the single factor weight matrix reflects the influence of the corresponding evaluation index on the health status evaluation of the battery pack;

[0134] The elements in the single factor weight matrix are the influence of each evaluation index on the battery health status evaluation. The higher the influence, the larger the value, and the sum of the weights is equal to 1.

[0135] Assume that, based on experience, the single factor weight matrix A = [0.55 0.2 0.15 0.1], then the comprehensive evaluation matrix B is:

[0136]

[0137] In order, the battery health status comments corresponding to the membership degrees 0, 0, 0, 0.2025, and 0.7975 in the comprehensive evaluation matrix B are 'poor', 'poor', 'average', 'good', and 'excellent'.

[0138] In step 300, a fuzzy comprehensive evaluation is performed according to the comprehensive evaluation matrix to obtain a comprehensive evaluation result, specifically, the comment with the largest membership value in the comprehensive evaluation matrix is ​​taken as the comprehensive evaluation result. Then, the maximum membership value in the comprehensive evaluation matrix B is 0.7975, and its corresponding comment is "excellent", so the current battery pack health status is "excellent".

[0139] In summary, this embodiment designs the cycle number index, consistency index, safety and reliability index and energy efficiency index of the battery pack, and combines the fuzzy comprehensive evaluation method to evaluate the health status of the battery pack from multiple dimensions, and comprehensively considers the sudden changes and gradual changes in the health status of the battery pack. Among them, the safety and reliability index can mainly reflect the sudden changes in the health status caused by sudden failures during daily operation of the battery pack, and the cycle number index, consistency index and energy efficiency index of the battery pack can mainly reflect the gradual changes in the health status caused by daily use and aging of the battery pack. At the same time, there is a certain correlation between the above indicators in theory. Therefore, the multiple evaluation indicators designed by this method can greatly improve the accuracy and robustness of the evaluation method.

[0140] In addition, this method mainly performs real-time evaluation based on data collected and stored during the daily operation of the battery pack. It does not need to disassemble the battery from the equipment for testing and can be performed during the daily operation of the equipment. Therefore, this method has good applicability and can be used for scenarios such as safety monitoring and management of daily operation of battery packs and cascade utilization of the battery pack when it is retired in energy storage systems.

[0141] Please refer to Figure 2 , Figure 2A functional module diagram of a battery pack health status evaluation device based on fuzzy comprehensive evaluation provided in an embodiment of the present application, the device specifically includes: an acquisition module 1, a construction module 2 and an evaluation module 3.

[0142] Among them, the acquisition module 1 is used to obtain the factor set and comment set for evaluating the health status of the battery pack; the evaluation indicators in the factor set include at least two of the cycle number indicator, consistency indicator, safety and reliability indicator and energy efficiency indicator; different comments in the comment set reflect different health status levels. The construction module 2 is used to construct a comprehensive evaluation matrix based on the factor set and the comment set. The evaluation module 3 is used to perform fuzzy comprehensive evaluation based on the comprehensive evaluation matrix to obtain a comprehensive evaluation result, and use the comprehensive evaluation result as the battery pack health status evaluation result.

[0143] In the embodiment of the present application, the acquisition module 1 is used to obtain the factor set and comment set for evaluating the health status of the battery pack, the construction module 2 is used to construct a comprehensive evaluation matrix, and the evaluation module 3 is used to perform fuzzy comprehensive evaluation to obtain a comprehensive evaluation result. Among them, the factor set includes indicators of multiple dimensions, specifically cycle number indicators, consistency indicators, safety and reliability indicators, and energy efficiency indicators. These indicators reflect the health status of the battery pack of the energy storage system from different dimensions. The device obtains the evaluation results of different evaluation indicators based on the comment set, and then uses the fuzzy comprehensive evaluation method to fully consider the influence of different comments and different evaluation indicators on the corresponding comprehensive evaluation results, so as to obtain accurate battery pack health status evaluation results.

[0144] In some optional implementations, the construction module 2 specifically includes: an evaluation index calculation module, a membership degree calculation module, a single factor matrix module and a comprehensive evaluation matrix module.

[0145] Among them, the evaluation index calculation module is used to obtain the original data of the battery pack and calculate the evaluation index value of the evaluation index based on the original data. The membership calculation module is used to determine the membership of each evaluation index corresponding to different comments based on the evaluation index value and the set evaluation standard value. The single factor matrix module is used to obtain the single factor evaluation matrix according to the membership of each evaluation index corresponding to different comments. The comprehensive evaluation matrix module is used to multiply the set single factor weight matrix with the single factor evaluation matrix to obtain a comprehensive evaluation matrix; wherein, the value of each element in the single factor weight matrix reflects the influence of the corresponding evaluation index on the health status evaluation of the battery pack.

[0146] The evaluation module 3 is also used to: take the comment with the largest membership value in the comprehensive evaluation matrix as the comprehensive evaluation result.

[0147] Figure 3 A possible structure of an electronic device provided by an embodiment of the present application is shown. Figure 3The electronic device includes: a processor 41, a memory 42 and a communication interface 43. These components are interconnected and communicate with each other through a communication bus 44 and / or other forms of connection mechanisms (not shown).

[0148] The memory 42 includes one or more (only one is shown in the figure), which may be, but not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), etc. The processor 41 and other possible components may access the memory 42, and read and / or write data therein.

[0149] The processor 41 includes one or more (only one is shown in the figure), which can be an integrated circuit chip with signal processing capabilities. The above-mentioned processor 41 can be a general-purpose processor, including a central processing unit (CPU), a micro control unit (MCU), a network processor (NP) or other conventional processors; it can also be a dedicated processor, including a neural network processor (NPU), a graphics processor (GPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. In addition, when there are multiple processors 41, some of them can be general-purpose processors and the other part can be dedicated processors.

[0150] The communication interface 43 includes one or more (only one is shown in the figure), which can be used to communicate directly or indirectly with other devices to exchange data. The communication interface 43 can include an interface for wired and / or wireless communication.

[0151] One or more computer program instructions may be stored in the memory 42 , and the processor 41 may read and execute these computer program instructions to implement the method provided in the embodiment of the present application.

[0152] Understandably, Figure 3 The structure shown is for illustration only. The electronic device may also include Figure 3 More or fewer components as shown, or with Figure 3 Different structures are shown. Figure 3 The components shown in the figure can be implemented by hardware, software or a combination thereof. The electronic device may be a physical device, such as a PC, a laptop, a tablet computer, a mobile phone, a server, an embedded device, etc., or a virtual device, such as a virtual machine, a virtualized container, etc. Moreover, the electronic device is not limited to a single device, but may also be a combination of multiple devices or a cluster consisting of a large number of devices.

[0153] The present application also provides a computer-readable storage medium on which computer program instructions are stored. When the computer program instructions are read and executed by a computer processor, the method provided by the present application is executed. For example, the computer-readable storage medium can be implemented as Figure 3 A memory 42 in an electronic device.

[0154] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0155] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0156] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0157] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0158] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery pack health status evaluation method based on fuzzy comprehensive evaluation, characterized in that: The method comprises: Obtaining a factor set and a comment set for evaluating the health status of a battery pack; the evaluation indicators in the factor set include at least two of a cycle number indicator, a consistency indicator, a safety and reliability indicator, and an energy efficiency indicator; different comments in the comment set reflect different health status levels; Constructing a comprehensive evaluation matrix based on the factor set and the comment set; A fuzzy comprehensive evaluation is performed according to the comprehensive evaluation matrix to obtain a comprehensive evaluation result, and the comprehensive evaluation result is used as a battery pack health status evaluation result.

2. The method according to claim 1, characterized in that The step of constructing a comprehensive evaluation matrix based on the factor set and the comment set includes: Acquiring raw data of the battery pack, and calculating an evaluation index value of the evaluation index according to the raw data; Determining the degree of membership of each evaluation indicator corresponding to different comments according to the evaluation indicator value and the set evaluation standard value; According to the membership degree of each evaluation indicator corresponding to different comments, a single factor evaluation matrix is ​​obtained; The set single factor weight matrix is ​​multiplied by the single factor evaluation matrix to obtain a comprehensive evaluation matrix; wherein the value of each element in the single factor weight matrix reflects the influence of the corresponding evaluation index on the health status evaluation of the battery pack; The fuzzy comprehensive evaluation is performed according to the comprehensive evaluation matrix to obtain a comprehensive evaluation result, including: The comment with the largest membership value in the comprehensive evaluation matrix is ​​taken as the comprehensive evaluation result.

3. The method according to claim 1, characterized in that The cycle number indicator is used to reflect the health status of the battery pack from the dimension of the number of charge and discharge cycles of the battery pack; The cycle number index is determined by the total cycle number at the end of the battery pack life and the cumulative cycle number of the battery pack up to the current moment; wherein the cumulative cycle number of the battery pack up to the current moment is determined by the cumulative discharge capacity or the cumulative charge capacity, and the nominal capacity of the battery pack.

4. The method according to claim 1, characterized in that The consistency index is used to reflect the health status of the battery pack from the dimension of voltage consistency between the battery cells of the battery pack; The consistency index is determined by the total number of battery cells in the battery pack and the number of non-repeated battery cells that have consistency problems as of the current moment; The method for determining whether the battery cell has a consistency problem includes: Determine whether the difference between the voltage of the battery cell and the average voltage of the battery cells of the battery pack is greater than a set multiple of the standard deviation of the battery cell voltage; If the standard deviation is greater than a set multiple, the battery cell has a consistency problem.

5. The method according to claim 1, characterized in that The safety reliability index is used to reflect the health status of the battery pack from the dimension of the number of battery pack failures; The safety reliability index is determined by the cumulative alarm days of each alarm item up to the current moment and the upper limit of the cumulative alarm days of each alarm item; The alarm items include at least one of a battery low temperature alarm, a battery high temperature alarm, a battery overvoltage alarm, a battery undervoltage alarm, and a battery insulation abnormality alarm.

6. The method according to claim 5, characterized in that The safety and reliability indicators are: Moreover, when When the value of is greater than 1, let SA equal to 0; SA∈[0,1]; Among them, d i is the cumulative number of alarm days for the ith alarm item as of the current moment, l i is the upper limit of the cumulative alarm days for the ith alarm item, and p is the total number of alarm items.

7. The method according to claim 1, characterized in that The energy efficiency index is used to reflect the health status of the battery pack from the dimension of the charging and discharging efficiency of the battery pack; The energy efficiency index is determined by the discharge energy of the battery pack when discharging from the highest value of the set SOC interval to the lowest value of the set SOC interval, and the charge energy of the battery pack when charging from the lowest value of the set SOC interval to the highest value of the set SOC interval.

8. A battery pack health status evaluation device based on fuzzy comprehensive evaluation, characterized in that: include: An acquisition module, used to acquire a factor set and a comment set for evaluating the health status of a battery pack; the evaluation indicators in the factor set include at least two of a cycle number indicator, a consistency indicator, a safety reliability indicator, and an energy efficiency indicator; different comments in the comment set reflect different health status levels; A construction module, used to construct a comprehensive evaluation matrix according to the factor set and the comment set; The evaluation module is used to perform fuzzy comprehensive evaluation according to the comprehensive evaluation matrix to obtain a comprehensive evaluation result, and use the comprehensive evaluation result as a battery pack health status evaluation result.

9. An electronic device, characterized in that: include: A processor and a memory, wherein the memory stores machine-readable instructions executable by the processor, and when the machine-readable instructions are executed by the processor, the method according to any one of claims 1 to 7 is performed.

10. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, which, when executed by a processor, executes the method according to any one of claims 1 to 7.

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