CN106353687B - A method for evaluating the state of health of lithium batteries - Google Patents
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 449
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Abstract
本发明提供一种锂电池健康状态的评估方法，所述方法包括：确定锂电池健康状态的评估因素；计算锂电池健康状态评估因素权重值的初始值；计算锂电池健康状态评估因素权重值的实际值；评估锂电池的健康状态。本发明综合锂电池的端电压变化率、欧姆内阻和极化内阻作为评估因素，提高了锂电池健康状态评估的准确性；采用在脉冲放电结束后，同时测量并计算锂电池端电压变化率、欧姆内阻和极化内阻的方法，保证了锂电池状态测量的状态同一性和时间一致性，提高了锂电池健康状态评估因素的准确性；综合了评估因素的标准差和平均数量指标的影响，更好的反映了评估因素在不同水平时的总体标志变动度，实现了锂电池健康状态的快速准确测量。
The present invention provides a method for evaluating the state of health of a lithium battery. The method includes: determining an evaluation factor for the state of health of a lithium battery; calculating an initial value of the weight value of the evaluation factor for the state of health of the lithium battery; Actual value; evaluates the state of health of the lithium battery. The invention integrates the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery as evaluation factors to improve the accuracy of the lithium battery state of health evaluation; after the pulse discharge is completed, the terminal voltage change rate of the lithium battery is measured and calculated at the same time. The methods of ohmic internal resistance and polarization internal resistance ensure the state identity and time consistency of lithium battery state measurement, and improve the accuracy of lithium battery state of health evaluation factors; the standard deviation and average quantity indicators of evaluation factors are integrated The influence of , better reflects the overall indicator variation of the evaluation factors at different levels, and realizes the rapid and accurate measurement of the health status of lithium batteries.
Description
技术领域technical field
本发明涉及一种评估方法，具体涉及一种锂电池健康状态的评估方法。The invention relates to an evaluation method, in particular to a lithium battery health state evaluation method.
背景技术Background technique
锂电池的SOH反映了锂电池组的安全性能和容量衰减程度,主要描述参数有总容量的衰减和锂电池内阻的变化等；由于意外的锂电池健康往往导致锂电池系统整体功能失效，从应用的角度对锂电池健康状况进行科学的估计和预测，进一步指导锂电池运行和维护，构建锂电池的状态监测和健康管理系统，防止锂电池过充、过放、估计锂电池性能状态和预测锂电池状态演变，是实现锂电池长时间可靠工作的重要参数，对于锂电池系统的任务决策、防止灾难性事故的发生具有重要意义。The SOH of the lithium battery reflects the safety performance and capacity attenuation of the lithium battery pack. The main parameters are the attenuation of the total capacity and the change of the internal resistance of the lithium battery. Due to the unexpected health of the lithium battery, the overall function of the lithium battery system often fails. From the perspective of scientific estimation and prediction of lithium battery health status, further guide lithium battery operation and maintenance, build lithium battery condition monitoring and health management system, prevent lithium battery from overcharge and over discharge, estimate lithium battery performance status and predict lithium battery performance The evolution of battery state is an important parameter to realize long-term reliable operation of lithium battery, which is of great significance for the task decision-making of lithium battery system and the prevention of catastrophic accidents.
目前常用的锂电池健康状态评估方法主要有：At present, the commonly used lithium battery health status assessment methods mainly include:
(1)完全充电(放电)测试方法，这种测试方法简单易行，但花时较长，且深度放电会影响锂电池的使用寿命；(1) Full charge (discharge) test method, which is simple and easy to implement, but takes a long time, and deep discharge will affect the service life of lithium batteries;
(2)循环次数折算法：是一种根据锂电池的使用次数来估算锂电池寿命的方法，该方法将锂电池的寿命等效成循环使用次数，然后根据锂电池循环次数与SOH的关系求得锂电池的SOH。(2) Cycle times conversion method: It is a method of estimating the life of a lithium battery according to the number of times of use of the lithium battery. Obtain the SOH of the lithium battery.
(3)基于锂电池充放电过程中的电流特征、电压特征和温度特征的评估策略，该方法需要对电流值、电压值和温度值进行计算，从而再对锂电池的电流特征、电压特征和温度特征进行提取计算，采用算法较多，计算过程比较繁杂，很难计算准确；(3) An evaluation strategy based on the current characteristics, voltage characteristics and temperature characteristics of the lithium battery during the charging and discharging process. This method needs to calculate the current value, voltage value and temperature value, so that the current characteristics, voltage characteristics and Extraction and calculation of temperature features requires many algorithms, the calculation process is complicated, and it is difficult to calculate accurately;
(4)阻抗分析法：阻抗分析法是当今最前沿的SOH测量方法，可以采用单一频率的交流信号来测量锂电池的SOH，但是这种方法不能反映全频率周期的锂电池SOH；需采用对锂电池输入不同频率的信号，对采集到的数据进行分析来估算锂电池参数进而判断锂电池的健康状态，该方法准确，但需专门的阻抗测试设备进行离线测量；(4) Impedance analysis method: Impedance analysis method is the most cutting-edge SOH measurement method today. It can measure the SOH of a lithium battery with an AC signal of a single frequency, but this method cannot reflect the SOH of a lithium battery with a full frequency cycle; The lithium battery inputs signals of different frequencies, and analyzes the collected data to estimate the parameters of the lithium battery and then judge the health status of the lithium battery. This method is accurate, but requires special impedance testing equipment for offline measurement;
(5)经验模型法：该方法对锂电池进行大量的实验，绘制锂电池的SOH与锂电池某一特征的关系图表，但是该方法针对不同的锂电池需要绘制不同的图表，耗时较长，局限性大。(5) Empirical model method: This method conducts a large number of experiments on lithium batteries, and draws a graph of the relationship between the SOH of the lithium battery and a certain feature of the lithium battery, but this method needs to draw different charts for different lithium batteries, which takes a long time. , the limitation is large.
发明内容SUMMARY OF THE INVENTION
为了克服上述现有技术的不足，本发明提供一种锂电池健康状态的评估方法，以锂电池的端电压变化率、欧姆内阻极化内阻作为锂电池健康状态(State ofHealth，SOH)的三个评估因素，根据这三个评估因素评估锂电池的健康状态。In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a method for evaluating the state of health of a lithium battery. Three evaluation factors, according to which the state of health of the lithium battery is evaluated.
为了实现上述发明目的，本发明采取如下技术方案：In order to realize the above-mentioned purpose of the invention, the present invention adopts the following technical solutions:
本发明提供一种锂电池健康状态的评估方法，所述方法包括：The present invention provides a method for evaluating the state of health of a lithium battery, the method comprising:
确定锂电池健康状态的评估因素；Evaluation factors to determine the state of health of lithium batteries;
计算锂电池健康状态评估因素权重值的初始值；Calculate the initial value of the weight value of the lithium battery state of health assessment factor;
计算锂电池健康状态评估因素权重值的实际值；Calculate the actual value of the weight value of the lithium battery state of health assessment factor;
评估锂电池的健康状态。Assess the state of health of lithium batteries.
所述锂电池健康状态评估因素包括锂电池的端电压变化率、欧姆内阻和极化内阻。The factors for evaluating the state of health of the lithium battery include the rate of change of the terminal voltage, the ohmic internal resistance and the polarization internal resistance of the lithium battery.
所述计算锂电池健康状态评估因素权重值的初始值包括：The initial value for calculating the weight value of the lithium battery state of health evaluation factor includes:
将锂电池的荷电状态调整为设定的荷电状态，并将其置于设定的温度环境中。Adjust the state of charge of the lithium battery to the set state of charge and place it in the set temperature environment.
所述计算锂电池健康状态评估因素权重值的初始值包括：The initial value for calculating the weight value of the lithium battery state of health evaluation factor includes:
确定锂电池的初始状态和衰减状态a、b、c，且a、b、c∈k，k表示锂电池的任意一种衰减状态；Determine the initial state and decay states a, b, and c of the lithium battery, and a, b, and c∈k, k represents any decay state of the lithium battery;
所述计算锂电池健康状态评估因素权重值的初始值包括：The initial value for calculating the weight value of the lithium battery state of health evaluation factor includes:
在锂电池的初始状态下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为初始状态下的截止电压U10时，锂电池停止放电，此时记录锂电池停止放电后初始状态下的突变电压U20，并记录Δt秒后初始状态下的端电压U30，于是，锂电池在初始状态下的端电压变化值ΔU0＝U30-U10；In the initial state of the lithium battery, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 10 in the initial state, the lithium battery stops discharging, and the initial state after the lithium battery stops discharging is recorded. and record the terminal voltage U 30 in the initial state after Δt seconds, so the change value of the terminal voltage of the lithium battery in the initial state ΔU 0 =U 30 -U 10 ;
计算锂电池在初始状态下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the initial state, as follows:
δ0＝ΔU0/Δt (1)δ 0 =ΔU 0 /Δt (1)
RΩ0＝(U20-U10)/I (2)R Ω0 = (U 20 -U 10 )/I (2)
Rd0＝(U30-U20)/I (3)R d0 = (U 30 -U 20 )/I (3)
其中，δ0、RΩ0和Rd0分别为锂电池在初始状态下的端电压变化率、欧姆内阻和极化内阻；Among them, δ 0 , R Ω0 and R d0 are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the initial state, respectively;
锂电池在衰减状态a下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态a下的截止电压U1a时，锂电池停止放电，此时记录锂电池停止放电后衰减状态a下的突变电压U2a，并记录Δt秒后衰减状态a下的端电压U3a，于是，锂电池在衰减状态a下的端电压变化值ΔUa＝U3a-U1a；When the lithium battery is in the decay state a, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1a in the decay state a, the lithium battery stops discharging, and the decay after the lithium battery stops discharging is recorded. The sudden change of voltage U 2a in state a, and the terminal voltage U 3a in decay state a after Δt seconds is recorded, so the change value of terminal voltage of lithium battery in decay state a is ΔU a =U 3a -U 1a ;
计算锂电池在衰减状态a下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state a, as follows:
δa＝ΔUa/Δt (4)δ a =ΔU a /Δt (4)
RΩa＝(U2a-U1a)/I (5)R Ωa =(U 2a -U 1a )/I (5)
Rda＝(U3a-U2a)/I (6)R da =(U 3a -U 2a )/I (6)
其中，δa、RΩa和Rda分别为锂电池在衰减状态a下的端电压变化率、欧姆内阻和极化内阻；Among them, δ a , R Ωa and R da are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state a, respectively;
锂电池在衰减状态b下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态b下的截止电压U1b时，锂电池停止放电，此时记录锂电池停止放电后衰减状态b下的突变电压U2b，并记录Δt秒后衰减状态b下的端电压U3b，于是，锂电池在衰减状态b下的端电压变化值ΔUb＝U3b-U1b；When the lithium battery is in the decay state b, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1b in the decay state b, the lithium battery stops discharging. At this time, the decay after the lithium battery stops discharging is recorded. The sudden change of voltage U 2b in state b, and the terminal voltage U 3b in decay state b after Δt seconds are recorded, so the change value of terminal voltage of lithium battery in decay state b ΔU b =U 3b -U 1b ;
计算锂电池在衰减状态b下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state b, as follows:
δb＝ΔUb/Δt (7)δ b =ΔU b /Δt (7)
RΩb＝(U2b-U1b)/I (8)R Ωb = (U 2b -U 1b )/I (8)
Rdb＝(U3b-U2b)/I (9)R db = (U 3b -U 2b )/I (9)
其中，δb、RΩb和Rdb分别为锂电池在衰减状态b下的端电压变化率、欧姆内阻和极化内阻；Among them, δ b , R Ωb and R db are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state b, respectively;
锂电池在衰减状态c下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态c下的截止电压U1c时，锂电池停止放电，此时记录锂电池停止放电后衰减状态c下的突变电压U2c，并记录Δt秒后衰减状态c下的端电压U3c，于是，锂电池在衰减状态c下的端电压变化值ΔUc＝U3c-U1c；When the lithium battery is in the decay state c, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1c in the decay state c, the lithium battery stops discharging. The sudden change of voltage U 2c in state c, and the terminal voltage U 3c in decay state c after Δt seconds is recorded, so the change value of terminal voltage of lithium battery in decay state c is ΔU c =U 3c -U 1c ;
计算锂电池在衰减状态c下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state c, as follows:
δc＝ΔUc/Δt (10)δ c =ΔU c /Δt (10)
RΩc＝(U2c-U1c)/I (11)R Ωc = (U 2c -U 1c )/I (11)
Rdc＝(U3c-U2c)/I (12)R dc = (U 3c -U 2c )/I (12)
其中，δc、RΩc和Rdc分别为锂电池在衰减状态c下的端电压变化率、欧姆内阻和极化内阻。Among them, δ c , R Ωc and R dc are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state c, respectively.
所述计算锂电池健康状态评估因素权重值的初始值包括：The initial value for calculating the weight value of the lithium battery state of health evaluation factor includes:
设初始状态下锂电池的初始容量为Q0，衰减状态a、b、c下锂电池的剩余容量分别为Qa、Qb和Qc，衰减状态a、b、c下锂电池的健康状态分别表示为：Let the initial capacity of the lithium battery in the initial state be Q 0 , the remaining capacities of the lithium battery in the decay states a, b, and c are Q a , Q b and Q c , respectively, and the health state of the lithium battery in the decay states a, b, and c They are respectively expressed as:
其中，SOHa、SOHb、SOHc分别为衰减状态a、b、c下锂电池的健康状态。Among them, SOH a , SOH b , and SOH c are the health states of the lithium battery in the decay states a, b, and c, respectively.
所述计算锂电池健康状态评估因素权重值的初始值包括：The initial value for calculating the weight value of the lithium battery state of health evaluation factor includes:
根据式(13)-(18)计算锂电池的端电压变化率、欧姆内阻、极化内阻的权重值的初始值，有：Calculate the initial value of the weight value of the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery according to equations (13)-(18), as follows:
其中，λ0为锂电池的端电压变化率的权重值的初始值，ρ0为锂电池的欧姆内阻的权重值的初始值，γ0为锂电池的极化内阻的权重值的初始值。Among them, λ 0 is the initial value of the weight value of the terminal voltage change rate of the lithium battery, ρ 0 is the initial value of the weight value of the ohmic internal resistance of the lithium battery, and γ 0 is the initial value of the weight value of the polarization internal resistance of the lithium battery value.
所述锂电池的端电压变化率、欧姆内阻和极化内阻的计算，包括：The calculation of the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery includes:
锂电池在衰减状态k下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态k下的截止电压U1k时，锂电池停止放电，此时记录锂电池停止放电后衰减状态k下的突变电压U2k，并记录Δt秒后衰减状态k下的端电压U3k，于是，锂电池在衰减状态k下的端电压变化值ΔUk＝U3k-U1k；When the lithium battery is in the decay state k, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1k in the decay state k, the lithium battery stops discharging. The sudden change of voltage U 2k in state k, and the terminal voltage U 3k in decay state k after Δt seconds is recorded, so the change value of terminal voltage of lithium battery in decay state k ΔU k =U 3k -U 1k ;
计算锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state k, there are:
δk＝ΔUk/Δt (19)δ k =ΔU k /Δt (19)
RΩk＝(U2k-U1k)/I (20)R Ωk = (U 2k -U 1k )/I (20)
Rdk＝(U3k-U2k)/I (21)R dk = (U 3k -U 2k )/I (21)
其中，δk、RΩk和Rdk分别为锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻权；Among them, δ k , R Ωk and R dk are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance weight of the lithium battery under the decay state k, respectively;
锂电池在衰减状态k-1下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态k-1下的截止电压U1(k-1)时，锂电池停止放电，此时记录锂电池停止放电后衰减状态k-1下的突变电压U2(k-1)，并记录Δt秒后衰减状态k-1下的端电压U3(k-1)，于是，锂电池在衰减状态k-1下的端电压变化值ΔUk-1＝U3(k-1)-U1(k-1)；When the lithium battery is in the decay state k-1, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1 (k-1) in the decay state k-1, the lithium battery stops discharging, At this time, record the sudden change voltage U 2(k-1) in the decay state k-1 after the lithium battery stops discharging, and record the terminal voltage U 3(k-1) in the decay state k-1 after Δt seconds. The terminal voltage change value of the battery in the decay state k-1 ΔU k-1 =U 3(k-1) -U 1(k-1) ;
计算锂电池在衰减状态k-1下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state k-1, as follows:
δk-1＝ΔUk-1/Δt (22)δ k-1 =ΔU k-1 /Δt (22)
RΩ(k-1)＝(U2(k-1)-U1(k-1))/I (23)R Ω(k-1) = (U 2(k-1) -U 1(k-1) )/I (23)
Rd(k-1)＝(U3(k-1)-U2(k-1))/I (24)R d(k-1) = (U 3(k-1) -U 2(k-1) )/I (24)
其中，δk-1、RΩ(k-1)和Rd(k-1)分别为锂电池在衰减状态k-1下的端电压变化率、欧姆内阻和极化内阻；Among them, δ k-1 , R Ω(k-1) and R d(k-1) are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state k-1, respectively;
锂电池在衰减状态i下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态k下的截止电压U1i时，锂电池停止放电，此时记录锂电池停止放电后衰减状态i下的突变电压U2i，并记录Δt秒后衰减状态i下的端电压U3i，于是，锂电池在衰减状态i下的端电压变化值ΔUi＝U3i-U1i；When the lithium battery is in the decay state i, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1i in the decay state k, the lithium battery stops discharging, and the decay after the lithium battery stops discharging is recorded. The sudden change of voltage U 2i in state i, and the terminal voltage U 3i in decay state i after Δt seconds are recorded, so the change value of terminal voltage of lithium battery in decay state i ΔU i =U 3i -U 1i ;
计算锂电池在衰减状态i下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state i, as follows:
δi＝ΔUi/Δt (25)δ i =ΔU i /Δt (25)
RΩi＝(U2i-U1i)/I (26)R Ωi = (U 2i -U 1i )/I (26)
Rdi＝(U3i-U2i)/I (27)R di = (U 3i -U 2i )/I (27)
其中，δi、RΩi和Rdi分别为锂电池在衰减状态i下的端电压变化率、欧姆内阻和极化内阻；Among them, δ i , R Ωi and R di are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state i, respectively;
锂电池在衰减状态i-1下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态i-1下的截止电压U1(i-1)时，锂电池停止放电，此时记录锂电池停止放电后衰减状态i-1下的突变电压U2(i-1)，并记录Δt秒后衰减状态i-1下的端电压U3(i-1)，于是，锂电池在衰减状态i-1下的端电压变化值ΔUi-1＝U3(i-1)-U1(i-1)；When the lithium battery is in the decay state i-1, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1 (i-1) in the decay state i-1, the lithium battery stops discharging, At this time, record the sudden change voltage U 2(i-1) in the decay state i-1 after the lithium battery stops discharging, and record the terminal voltage U 3(i-1) in the decay state i-1 after Δt seconds. The terminal voltage change value of the battery in the decay state i-1 ΔU i-1 =U 3(i-1) -U 1(i-1) ;
计算锂电池在衰减状态i-1下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state i-1, there are:
δi-1＝ΔUi-1/Δt (28)δ i-1 =ΔU i-1 /Δt (28)
RΩ(i-1)＝(U2(i-1)-U1(i-1))/I (29)R Ω(i-1) = (U 2(i-1) -U 1(i-1) )/I (29)
Rd(i-1)＝(U3(i-1)-U2(i-1))/I (30)R d(i-1) = (U 3(i-1) -U 2(i-1) )/I (30)
其中，δi-1、RΩ(i-1)和Rd(i-1)分别为锂电池在衰减状态i-1下的端电压变化率、欧姆内阻和极化内阻；Among them, δ i-1 , R Ω(i-1) and R d(i-1) are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state i-1, respectively;
锂电池在衰减状态m下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态m下的截止电压U1m时，锂电池停止放电，此时记录锂电池停止放电后衰减状态m下的突变电压U2m，并记录Δt秒后衰减状态i下的端电压U3m，于是，锂电池在衰减状态m下的端电压变化值ΔUm＝U3m-U1m；When the lithium battery is in the decay state m, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1m in the decay state m, the lithium battery stops discharging. The sudden change of voltage U 2m in the state m, and the terminal voltage U 3m in the decay state i after Δt seconds is recorded, so the change value of the terminal voltage of the lithium battery in the decay state m is ΔU m =U 3m -U 1m ;
计算锂电池在衰减状态m下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state m, as follows:
δm＝ΔUm/Δt (31)δ m =ΔU m /Δt (31)
RΩm＝(U2m-U1m)/I (32)R Ωm = (U 2m -U 1m )/I (32)
Rdm＝(U3m-U2m)/I (33)R dm = (U 3m -U 2m )/I (33)
其中，δm、RΩm和Rdm分别为锂电池在衰减状态m下的端电压变化率、欧姆内阻和极化内阻。Among them, δ m , R Ωm and R dm are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state m, respectively.
所述计算锂电池健康状态评估因素权重值的实际值包括：The actual value of calculating the weight value of the lithium battery state of health evaluation factor includes:
计算锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻的标准差系数，有：Calculate the standard deviation coefficient of the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state k, as follows:
其中，V1k、V2k和V3k分别为锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻的标准差系数；σ1k、σ2k和σ3k分别为锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻的标准差，且有
所述计算锂电池健康状态评估因素权重值的实际值包括：The actual value of calculating the weight value of the lithium battery state of health evaluation factor includes:
计算锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻权重系数，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance weight coefficient of the lithium battery in the decay state k, as follows:
其中，λk、ρk和γk分别为锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻的权重系数；V1i、V2i和V3i分别为衰减状态i下锂电池的端电压变化率、欧姆内阻和极化内阻的标准差系数，且有
所述评估锂电池的健康状态包括：The evaluation of the state of health of the lithium battery includes:
计算锂电池在衰减状态k下的健康状态，有：Calculate the health state of the lithium battery in the decay state k, there are:
SOHk＝(λk*F1k+ρk*F2k+γk*F3k)*100％ (40)SOH k =(λ k *F 1k +ρ k *F 2k +γ k *F 3k )*100% (40)
其中，SOHk为锂电池在衰减状态k下的健康状态，SOHk越大，表明锂电池健康状态越好。Among them, SOH k is the health state of the lithium battery in the decay state k, and the larger the SOH k , the better the health state of the lithium battery.
与最接近的现有技术相比，本发明提供的技术方案具有以下有益效果：Compared with the closest prior art, the technical solution provided by the present invention has the following beneficial effects:
1、实现了锂电池健康状态的快速准确测量；1. Realize the fast and accurate measurement of the health status of lithium batteries;
2、综合锂电池外特征变化(锂电池的端电压变化率)和内特征变化(欧姆内阻和极化内阻)作为评估因素，提高了锂电池健康状态评估的准确性；2. The change of external characteristics of lithium battery (the rate of change of terminal voltage of lithium battery) and the change of internal characteristics (ohmic internal resistance and polarization internal resistance) are used as evaluation factors to improve the accuracy of lithium battery state of health evaluation;
3、采用在脉冲放电结束后，同时测量并计算锂电池端电压变化率、欧姆内阻和极化内阻的方法，保证了锂电池状态测量的状态同一性和时间一致性，提高了锂电池健康状态评估因素的准确性；3. The method of measuring and calculating the voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery at the same time after the pulse discharge is completed ensures the state identity and time consistency of the lithium battery state measurement and improves the health of the lithium battery Accuracy of status assessment factors;
4、不同评估因素采用不同的权重，并且在锂电池衰减过程中，根据不同评估因素的变化调整权重值，提高了锂电池健康状态评估的准确性；4. Different evaluation factors use different weights, and in the process of lithium battery decay, the weight value is adjusted according to the changes of different evaluation factors, which improves the accuracy of lithium battery state of health evaluation;
5、采用标准差系数计算锂电池健康状态评估因素的权重系数，不受评估因素物理单位的影响；5. The standard deviation coefficient is used to calculate the weight coefficient of the lithium battery health status evaluation factor, which is not affected by the physical unit of the evaluation factor;
6、方法综合了评估因素的标准差和平均数量指标的影响，更好的反映了评估因素在不同水平时的总体标志变动度。6. The method synthesizes the influence of the standard deviation of the evaluation factors and the average quantity index, and better reflects the overall indicator variation of the evaluation factors at different levels.
附图说明Description of drawings
图1是本发明实施例中脉冲电流使锂电池放电时的电压随时间变化的特性图；Fig. 1 is the characteristic diagram of the voltage change with time when the pulse current makes the lithium battery discharge in the embodiment of the present invention;
图2是本发明实施例中脉冲电流随时间变化的特性图。FIG. 2 is a characteristic diagram of the pulse current changing with time in the embodiment of the present invention.
具体实施方式Detailed ways
下面结合附图对本发明作进一步详细说明。The present invention will be further described in detail below in conjunction with the accompanying drawings.
在锂电池的老化过程中，由于锂电池内部物质活性的降低，电阻变大，锂电池的容量和锂电池端电压的变化率都会发生变化，可以根据锂电池端电压与容量的关系来测量健康状态SOH(State ofHealth，SOH)。这种测量方法简单快速，但单独用锂电池端电压变化速率来判断锂电池的健康状态存在一定偏差；由于锂电池的内阻与SOH也存在一定的关系，SOH越低，锂电池内阻越大，通过检测电压、电流、温度等数据，可以间接计算出锂电池的内阻值，然后根据SOH与锂电池内阻的关系计算求得SOH。但是锂电池的内阻在SOH变化范围不大时变化不明显，而当锂电池老化严重时电阻值的变化较大，因而该方法在SOH变化较小时测量的误差会较大。During the aging process of the lithium battery, due to the decrease of the activity of the internal material of the lithium battery and the increase of the resistance, the capacity of the lithium battery and the rate of change of the terminal voltage of the lithium battery will change. The state of health SOH can be measured according to the relationship between the terminal voltage and the capacity of the lithium battery. (State of Health, SOH). This measurement method is simple and fast, but there is a certain deviation in judging the health status of the lithium battery by using the change rate of the terminal voltage of the lithium battery alone; because the internal resistance of the lithium battery also has a certain relationship with the SOH, the lower the SOH, the greater the internal resistance of the lithium battery. By detecting data such as voltage, current, temperature, etc., the internal resistance of the lithium battery can be indirectly calculated, and then the SOH can be calculated according to the relationship between the SOH and the internal resistance of the lithium battery. However, the internal resistance of the lithium battery does not change significantly when the SOH variation range is not large, and when the lithium battery is seriously aged, the resistance value changes greatly, so the measurement error of this method will be larger when the SOH change is small.
本发明公开了一种采用锂电池在一个的固定的脉冲电流作用下，测量锂电池放电至一个固定的截止电压之后的端电压值的变化，从而得出端电压变化率，作为锂电池健康状态的一个评估因素，再计算锂电池的内阻(包括欧姆内阻和极化内阻)作为另两个评估因素，采用这三个评估因素权重相加后来判断锂电池的健康状态。采用锂电池端电压变化率作为进行锂电池健康状态评估的外特征参数；采用锂电池内阻作为进行锂电池健康状态评估的内特征参数，同时，为更利于计算分析，将锂电池内阻分解为欧姆内阻和极化内阻，以这三个评估参数权重相加后作为综合评估参数，并且随着锂电池老化过程中状态的变化，不断调整三个评估参数的权重，以此来修正综合评估参数；通过该方法能够实现锂电池健康状态的在线评测，相比以往的单一参数，更加准确，提高了锂电池使用过程中的安全性。The invention discloses a method of measuring the change of the terminal voltage value after the lithium battery is discharged to a fixed cut-off voltage by using a lithium battery under the action of a fixed pulse current, so as to obtain the terminal voltage change rate as the state of health of the lithium battery Then calculate the internal resistance of the lithium battery (including ohmic internal resistance and polarization internal resistance) as the other two evaluation factors, and use the weights of these three evaluation factors to add up to determine the state of health of the lithium battery. The rate of change of the terminal voltage of the lithium battery is used as the external characteristic parameter for the evaluation of the state of health of the lithium battery; the internal resistance of the lithium battery is used as the internal characteristic parameter for the evaluation of the state of health of the lithium battery. Resistance and polarization internal resistance, the weights of these three evaluation parameters are added together as a comprehensive evaluation parameter, and as the state of the lithium battery changes during the aging process, the weights of the three evaluation parameters are continuously adjusted to correct the comprehensive evaluation parameters. The method can realize the online evaluation of the health state of the lithium battery, which is more accurate than the previous single parameter, and improves the safety of the lithium battery during use.
1.本发明提出了采用锂电池端电压变化率作为锂电池健康状态的一个评估因素。1. The present invention proposes to use the change rate of the terminal voltage of the lithium battery as an evaluation factor for the state of health of the lithium battery.
在锂电池循环运行过程中，随着循环次数或工况运行时间的增加，锂电池逐渐衰减，在相同温度和荷电状态时，在锂电池上施加脉冲电流放电至相同截止电压后静置，锂电池端电压的变化速率并不相同，测试并计算变化率并以此作为锂电池SOH的一个重要判据。During the cycle operation of the lithium battery, with the increase of the number of cycles or the operating time of the working condition, the lithium battery gradually decays. At the same temperature and state of charge, a pulse current is applied to the lithium battery to discharge to the same cut-off voltage, and then the lithium battery rests. The rate of change of the battery terminal voltage is not the same. Test and calculate the rate of change and use it as an important criterion for the SOH of lithium batteries.
2.本发明提出了采用脉冲电流测试并计算锂电池的欧姆内阻和极化内阻，以欧姆内阻和极化内阻作为锂电池健康状态的另两个评估因素。2. The present invention proposes to measure and calculate the ohmic internal resistance and polarization internal resistance of the lithium battery by using pulse current, and use the ohmic internal resistance and the polarization internal resistance as the other two evaluation factors for the health status of the lithium battery.
3.本发明提出根据1和2中计算得到的三个评估因素，加以不同的权重值，并根据锂电池的不同衰减程度，调整权重值，准确计算全寿命周期内锂电池的健康状态。3. The present invention proposes to add different weight values according to the three evaluation factors calculated in 1 and 2, and adjust the weight values according to different attenuation degrees of the lithium battery, so as to accurately calculate the health state of the lithium battery in the whole life cycle.
本发明提供一种锂电池健康状态的评估方法，所述方法包括：The present invention provides a method for evaluating the state of health of a lithium battery, the method comprising:
确定锂电池健康状态的评估因素；Evaluation factors to determine the state of health of lithium batteries;
计算锂电池健康状态评估因素权重值的初始值；Calculate the initial value of the weight value of the lithium battery state of health assessment factor;
计算锂电池健康状态评估因素权重值的实际值；Calculate the actual value of the weight value of the lithium battery state of health assessment factor;
评估锂电池的健康状态。Assess the state of health of lithium batteries.
所述锂电池健康状态评估因素包括锂电池的端电压变化率、欧姆内阻和极化内阻。The factors for evaluating the state of health of the lithium battery include the rate of change of the terminal voltage, the ohmic internal resistance and the polarization internal resistance of the lithium battery.
所述计算锂电池健康状态评估因素权重值的初始值包括：The initial value for calculating the weight value of the lithium battery state of health evaluation factor includes:
将锂电池的荷电状态调整为设定的荷电状态，并将其置于设定的温度环境中。Adjust the state of charge of the lithium battery to the set state of charge and place it in the set temperature environment.
所述计算锂电池健康状态评估因素权重值的初始值包括：The initial value for calculating the weight value of the lithium battery state of health evaluation factor includes:
确定锂电池的初始状态和衰减状态a、b、c，且a、b、c∈k，k表示锂电池的任意一种衰减状态；Determine the initial state and decay states a, b, and c of the lithium battery, and a, b, and c∈k, k represents any decay state of the lithium battery;
所述计算锂电池健康状态评估因素权重值的初始值包括：The initial value for calculating the weight value of the lithium battery state of health evaluation factor includes:
在锂电池的初始状态下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为初始状态下的截止电压U10时，锂电池停止放电，此时记录锂电池停止放电后初始状态下的突变电压U20，并记录Δt秒后初始状态下的端电压U30，于是，锂电池在初始状态下的端电压变化值ΔU0＝U30-U10；In the initial state of the lithium battery, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 10 in the initial state, the lithium battery stops discharging, and the initial state after the lithium battery stops discharging is recorded. and record the terminal voltage U 30 in the initial state after Δt seconds, so the change value of the terminal voltage of the lithium battery in the initial state ΔU 0 =U 30 -U 10 ;
计算锂电池在初始状态下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the initial state, as follows:
δ0＝ΔU0/Δt (1)δ 0 =ΔU 0 /Δt (1)
RΩ0＝(U20-U10)/I (2)R Ω0 = (U 20 -U 10 )/I (2)
Rd0＝(U30-U20)/I (3)R d0 = (U 30 -U 20 )/I (3)
其中，δ0、RΩ0和Rd0分别为锂电池在初始状态下的端电压变化率、欧姆内阻和极化内阻；Among them, δ 0 , R Ω0 and R d0 are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the initial state, respectively;
锂电池在衰减状态a下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态a下的截止电压U1a时，锂电池停止放电，此时记录锂电池停止放电后衰减状态a下的突变电压U2a，并记录Δt秒后衰减状态a下的端电压U3a，于是，锂电池在衰减状态a下的端电压变化值ΔUa＝U3a-U1a；When the lithium battery is in the decay state a, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1a in the decay state a, the lithium battery stops discharging, and the decay after the lithium battery stops discharging is recorded. The sudden change of voltage U 2a in state a, and the terminal voltage U 3a in decay state a after Δt seconds is recorded, so the change value of terminal voltage of lithium battery in decay state a is ΔU a =U 3a -U 1a ;
计算锂电池在衰减状态a下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state a, as follows:
δa＝ΔUa/Δt (4)δ a =ΔU a /Δt (4)
RΩa＝(U2a-U1a)/I (5)R Ωa =(U 2a -U 1a )/I (5)
Rda＝(U3a-U2a)/I (6)R da =(U 3a -U 2a )/I (6)
其中，δa、RΩa和Rda分别为锂电池在衰减状态a下的端电压变化率、欧姆内阻和极化内阻；Among them, δ a , R Ωa and R da are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state a, respectively;
锂电池在衰减状态b下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态b下的截止电压U1b时，锂电池停止放电，此时记录锂电池停止放电后衰减状态b下的突变电压U2b，并记录Δt秒后衰减状态b下的端电压U3b，于是，锂电池在衰减状态b下的端电压变化值ΔUb＝U3b-U1b；When the lithium battery is in the decay state b, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1b in the decay state b, the lithium battery stops discharging. At this time, the decay after the lithium battery stops discharging is recorded. The sudden change of voltage U 2b in state b, and the terminal voltage U 3b in decay state b after Δt seconds are recorded, so the change value of terminal voltage of lithium battery in decay state b ΔU b =U 3b -U 1b ;
计算锂电池在衰减状态b下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state b, as follows:
δb＝ΔUb/Δt (7)δ b =ΔU b /Δt (7)
RΩb＝(U2b-U1b)/I (8)R Ωb = (U 2b -U 1b )/I (8)
Rdb＝(U3b-U2b)/I (9)R db = (U 3b -U 2b )/I (9)
其中，δb、RΩb和Rdb分别为锂电池在衰减状态b下的端电压变化率、欧姆内阻和极化内阻；Among them, δ b , R Ωb and R db are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state b, respectively;
锂电池在衰减状态c下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态c下的截止电压U1c时，锂电池停止放电，此时记录锂电池停止放电后衰减状态c下的突变电压U2c，并记录Δt秒后衰减状态c下的端电压U3c，于是，锂电池在衰减状态c下的端电压变化值ΔUc＝U3c-U1c；When the lithium battery is in the decay state c, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1c in the decay state c, the lithium battery stops discharging. The sudden change of voltage U 2c in state c, and the terminal voltage U 3c in decay state c after Δt seconds is recorded, so the change value of terminal voltage of lithium battery in decay state c is ΔU c =U 3c -U 1c ;
计算锂电池在衰减状态c下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state c, as follows:
δc＝ΔUc/Δt (10)δ c =ΔU c /Δt (10)
RΩc＝(U2c-U1c)/I (11)R Ωc = (U 2c -U 1c )/I (11)
Rdc＝(U3c-U2c)/I (12)R dc = (U 3c -U 2c )/I (12)
其中，δc、RΩc和Rdc分别为锂电池在衰减状态c下的端电压变化率、欧姆内阻和极化内阻。Among them, δ c , R Ωc and R dc are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state c, respectively.
所述计算锂电池健康状态评估因素权重值的初始值包括：The initial value for calculating the weight value of the lithium battery state of health evaluation factor includes:
设初始状态下锂电池的初始容量为Q0，衰减状态a、b、c下锂电池的剩余容量分别为Qa、Qb和Qc，衰减状态a、b、c下锂电池的健康状态分别表示为：Let the initial capacity of the lithium battery in the initial state be Q 0 , the remaining capacities of the lithium battery in the decay states a, b, and c are Q a , Q b and Q c , respectively, and the health state of the lithium battery in the decay states a, b, and c They are respectively expressed as:
其中，SOHa、SOHb、SOHc分别为衰减状态a、b、c下锂电池的健康状态。Among them, SOH a , SOH b , and SOH c are the health states of the lithium battery in the decay states a, b, and c, respectively.
所述计算锂电池健康状态评估因素权重值的初始值包括：The initial value for calculating the weight value of the lithium battery state of health evaluation factor includes:
根据式(13)-(18)计算锂电池的端电压变化率、欧姆内阻、极化内阻的权重值的初始值，有：Calculate the initial value of the weight value of the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery according to equations (13)-(18), as follows:
其中，λ0为锂电池的端电压变化率的权重值的初始值，ρ0为锂电池的欧姆内阻的权重值的初始值，γ0为锂电池的极化内阻的权重值的初始值。Among them, λ 0 is the initial value of the weight value of the terminal voltage change rate of the lithium battery, ρ 0 is the initial value of the weight value of the ohmic internal resistance of the lithium battery, and γ 0 is the initial value of the weight value of the polarization internal resistance of the lithium battery value.
锂电池的端电压变化率、欧姆内阻和极化内阻的计算，包括：Calculation of terminal voltage change rate, ohmic internal resistance and polarization internal resistance of lithium batteries, including:
锂电池在衰减状态k下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态k下的截止电压U1k时，锂电池停止放电，此时记录锂电池停止放电后衰减状态k下的突变电压U2k，并记录Δt秒后衰减状态k下的端电压U3k，于是，锂电池在衰减状态k下的端电压变化值ΔUk＝U3k-U1k；对某一型号锂电池，I、U1k和Δt在整个评估过程中取相同的固定值；图1表示脉冲电流使锂电池放电时的电压随时间变化的特性图，横轴表示时间，纵轴表示电压；图2表示脉冲电流随时间变化的特性图，横轴表示时间，纵轴表示电流。When the lithium battery is in the decay state k, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1k in the decay state k, the lithium battery stops discharging. The sudden change of voltage U 2k in state k, and the terminal voltage U 3k in decay state k after Δt seconds are recorded, so the change value of terminal voltage of lithium battery in decay state k ΔU k =U 3k -U 1k ; for a certain For the type lithium battery, I, U 1k and Δt take the same fixed value throughout the evaluation process; Figure 1 shows the characteristic diagram of the voltage change with time when the lithium battery is discharged by the pulse current, the horizontal axis represents time, and the vertical axis represents voltage; FIG. 2 shows a characteristic diagram of pulse current changing with time, in which the horizontal axis represents time and the vertical axis represents current.
计算锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state k, there are:
δk＝ΔUk/Δt (19)δ k =ΔU k /Δt (19)
RΩk＝(U2k-U1k)/I (20)R Ωk = (U 2k -U 1k )/I (20)
Rdk＝(U3k-U2k)/I (21)R dk = (U 3k -U 2k )/I (21)
其中，δk、RΩk和Rdk分别为锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻；Among them, δ k , R Ωk and R dk are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state k, respectively;
锂电池在衰减状态k-1下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态k-1下的截止电压U1(k-1)时，锂电池停止放电，此时记录锂电池停止放电后衰减状态k-1下的突变电压U2(k-1)，并记录Δt秒后衰减状态k-1下的端电压U3(k-1)，于是，锂电池在衰减状态k-1下的端电压变化值ΔUk-1＝U3(k-1)-U1(k-1)；When the lithium battery is in the decay state k-1, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1 (k-1) in the decay state k-1, the lithium battery stops discharging, At this time, record the sudden change voltage U 2(k-1) in the decay state k-1 after the lithium battery stops discharging, and record the terminal voltage U 3(k-1) in the decay state k-1 after Δt seconds. The terminal voltage change value of the battery in the decay state k-1 ΔU k-1 =U 3(k-1) -U 1(k-1) ;
计算锂电池在衰减状态k-1下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state k-1, as follows:
δk-1＝ΔUk-1/Δt (22)δ k-1 =ΔU k-1 /Δt (22)
RΩ(k-1)＝(U2(k-1)-U1(k-1))/I (23)R Ω(k-1) = (U 2(k-1) -U 1(k-1) )/I (23)
Rd(k-1)＝(U3(k-1)-U2(k-1))/I (24)R d(k-1) = (U 3(k-1) -U 2(k-1) )/I (24)
其中，δk-1、RΩ(k-1)和Rd(k-1)分别为锂电池在衰减状态k-1下的端电压变化率、欧姆内阻和极化内阻；Among them, δ k-1 , R Ω(k-1) and R d(k-1) are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state k-1, respectively;
锂电池在衰减状态i下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态k下的截止电压U1i时，锂电池停止放电，此时记录锂电池停止放电后衰减状态i下的突变电压U2i，并记录Δt秒后衰减状态i下的端电压U3i，于是，锂电池在衰减状态i下的端电压变化值ΔUi＝U3i-U1i；When the lithium battery is in the decay state i, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1i in the decay state k, the lithium battery stops discharging, and the decay after the lithium battery stops discharging is recorded. The sudden change of voltage U 2i in state i, and the terminal voltage U 3i in decay state i after Δt seconds are recorded, so the change value of terminal voltage of lithium battery in decay state i ΔU i =U 3i -U 1i ;
计算锂电池在衰减状态i下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state i, as follows:
δi＝ΔUi/Δt (25)δ i =ΔU i /Δt (25)
RΩi＝(U2i-U1i)/I (26)R Ωi = (U 2i -U 1i )/I (26)
Rdi＝(U3i-U2i)/I (27)R di = (U 3i -U 2i )/I (27)
其中，δi、RΩi和Rdi分别为锂电池在衰减状态i下的端电压变化率、欧姆内阻和极化内阻；Among them, δ i , R Ωi and R di are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state i, respectively;
锂电池在衰减状态i-1下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态i-1下的截止电压U1(i-1)时，锂电池停止放电，此时记录锂电池停止放电后衰减状态i-1下的突变电压U2(i-1)，并记录Δt秒后衰减状态i-1下的端电压U3(i-1)，于是，锂电池在衰减状态i-1下的端电压变化值ΔUi-1＝U3(i-1)-U1(i-1)；When the lithium battery is in the decay state i-1, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1 (i-1) in the decay state i-1, the lithium battery stops discharging, At this time, record the sudden change voltage U 2(i-1) in the decay state i-1 after the lithium battery stops discharging, and record the terminal voltage U 3(i-1) in the decay state i-1 after Δt seconds. The terminal voltage change value of the battery in the decay state i-1 ΔU i-1 =U 3(i-1) -U 1(i-1) ;
计算锂电池在衰减状态i-1下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state i-1, there are:
δi-1＝ΔUi-1/Δt (28)δ i-1 =ΔU i-1 /Δt (28)
RΩ(i-1)＝(U2(i-1)-U1(i-1))/I (29)R Ω(i-1) = (U 2(i-1) -U 1(i-1) )/I (29)
Rd(i-1)＝(U3(i-1)-U2(i-1))/I (30)R d(i-1) = (U 3(i-1) -U 2(i-1) )/I (30)
其中，δi-1、RΩ(i-1)和Rd(i-1)分别为锂电池在衰减状态i-1下的端电压变化率、欧姆内阻和极化内阻；Among them, δ i-1 , R Ω(i-1) and R d(i-1) are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state i-1, respectively;
锂电池在衰减状态m下，通过脉冲电流I使锂电池放电，放电至锂电池的端电压为衰减状态m下的截止电压U1m时，锂电池停止放电，此时记录锂电池停止放电后衰减状态m下的突变电压U2m，并记录Δt秒后衰减状态i下的端电压U3m，于是，锂电池在衰减状态m下的端电压变化值ΔUm＝U3m-U1m；When the lithium battery is in the decay state m, the lithium battery is discharged through the pulse current I, and when the terminal voltage of the lithium battery is the cut-off voltage U 1m in the decay state m, the lithium battery stops discharging. The sudden change of voltage U 2m in the state m, and the terminal voltage U 3m in the decay state i after Δt seconds is recorded, so the change value of the terminal voltage of the lithium battery in the decay state m is ΔU m =U 3m -U 1m ;
计算锂电池在衰减状态m下的端电压变化率、欧姆内阻和极化内阻，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state m, as follows:
δm＝ΔUm/Δt (31)δ m =ΔU m /Δt (31)
RΩm＝(U2m-U1m)/I (32)R Ωm = (U 2m -U 1m )/I (32)
Rdm＝(U3m-U2m)/I (33)R dm = (U 3m -U 2m )/I (33)
其中，δm、RΩm和Rdm分别为锂电池在衰减状态m下的端电压变化率、欧姆内阻和极化内阻。Among them, δ m , R Ωm and R dm are the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state m, respectively.
所述计算锂电池健康状态评估因素权重值的实际值包括：The actual value of calculating the weight value of the lithium battery state of health evaluation factor includes:
计算锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻的标准差系数，有：Calculate the standard deviation coefficient of the terminal voltage change rate, ohmic internal resistance and polarization internal resistance of the lithium battery in the decay state k, as follows:
其中，V1k、V2k和V3k分别为锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻的标准差系数；σ1k、σ2k和σ3k分别为锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻的标准差，且有
所述计算锂电池健康状态评估因素权重值的实际值包括：The actual value of calculating the weight value of the lithium battery state of health evaluation factor includes:
计算锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻权重系数，有：Calculate the terminal voltage change rate, ohmic internal resistance and polarization internal resistance weight coefficient of the lithium battery in the decay state k, as follows:
其中，λk、ρk和γk分别为锂电池在衰减状态k下的端电压变化率、欧姆内阻和极化内阻的权重系数；V1i、V2i和V3i分别为衰减状态i下锂电池的端电压变化率、欧姆内阻和极化内阻的标准差系数，且有
所述评估锂电池的健康状态包括：The evaluation of the state of health of the lithium battery includes:
计算锂电池在衰减状态k下的健康状态，有：Calculate the health state of the lithium battery in the decay state k, there are:
SOHk＝(λk*F1k+ρk*F2k+γk*F3k)*100％ (40)SOH k =(λ k *F 1k +ρ k *F 2k +γ k *F 3k )*100% (40)
其中，SOHk为锂电池在衰减状态k下的健康状态，SOHk越大，表明锂电池健康状态越好。Among them, SOH k is the health state of the lithium battery in the decay state k, and the larger the SOH k , the better the health state of the lithium battery.
最后应当说明的是：以上实施例仅用以说明本发明的技术方案而非对其限制，所属领域的普通技术人员参照上述实施例依然可以对本发明的具体实施方式进行修改或者等同替换，这些未脱离本发明精神和范围的任何修改或者等同替换，均在申请待批的本发明的权利要求保护范围之内。Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Those of ordinary skill in the art can still modify or equivalently replace the specific embodiments of the present invention with reference to the above embodiments. Any modifications or equivalent substitutions that depart from the spirit and scope of the present invention are all within the protection scope of the claims of the present invention for which the application is pending.
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