CN115219933B - Liquid-cooled battery pack health state assessment method - Google Patents
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Abstract
本发明公开了一种液冷式电池包健康状态评估方法，事先对电池包样品进行测试标定以分别获得寿命起始点和寿命终止点电池包样品的环境温度及与之对应的吸热率所构成的数据表格；电池包产品出厂后的使用过程中，对于每一次充电过程，记录当次充电过程的环境温度平均值，统计并计算得到电池包的吸热率，查询数据表格分别获得寿命起始点和寿命终止点电池包在当次充电过程的环境温度平均值下所对应的吸热率值，计算当次充电过程的电池包健康状态并予以存储，根据存储数据输出最终电池包健康状态至用户。该方法从充电过程液冷板吸热量相对电池包充电量的比值的变化情况来反映电池包健康状态，具有实施简单方便、通用性好、准确度和可靠度高的优点。
The present invention discloses a method for evaluating the health status of a liquid-cooled battery pack. The battery pack samples are tested and calibrated in advance to obtain a data table consisting of the ambient temperature of the battery pack samples at the start point and end point of the life and the corresponding heat absorption rate; during the use of the battery pack product after leaving the factory, for each charging process, the average value of the ambient temperature of the charging process is recorded, the heat absorption rate of the battery pack is statistically calculated, the data table is queried to obtain the heat absorption rate values corresponding to the average value of the ambient temperature of the battery pack at the start point and end point of the life in the charging process, the health status of the battery pack in the charging process is calculated and stored, and the final battery pack health status is output to the user based on the stored data. The method reflects the health status of the battery pack from the change in the ratio of the heat absorption of the liquid cooling plate to the battery pack charge during the charging process, and has the advantages of simple and convenient implementation, good versatility, high accuracy and reliability.
Description
技术领域Technical Field
本发明涉及电池领域，具体涉及一种液冷式电池包健康状态评估方法。The present invention relates to the field of batteries, and in particular to a method for evaluating the health status of a liquid-cooled battery pack.
背景技术Background Art
作为一种化学储能电源，电池常以多个单体构成电池包并搭配冷却系统的形式向外界提供电能，其中液冷系统因冷却能力强、环境适应性好和温度一致性高等优点而广泛用于电池包的冷却。电池包工作过程因各种内外因素而不可避免地发生性能衰减现象，故人们需要准确地掌握电池包工作过程的健康状态。电池健康状态的英文表述为State ofhealth，简称SOH。电池SOH表征当前电池相对于新电池存储和释放电能的能力，以百分比的形式表示电池从寿命开始到寿命结束期间所处的状态，用来定量描述当前电池的性能状态。电池的性能指标较多，国内外对SOH有多种定义，概念上缺乏统一，目前SOH的定义主要体现在容量、电量、内阻、循环次数和峰值功率等几个方面。譬如，以容量定义时，SOH为电池当前容量与电池额定容量之比。As a chemical energy storage power source, batteries often provide electrical energy to the outside world in the form of multiple monomers forming a battery pack and equipped with a cooling system. Among them, liquid cooling systems are widely used for cooling battery packs due to their strong cooling capacity, good environmental adaptability and high temperature consistency. The performance of the battery pack will inevitably decay due to various internal and external factors during its operation, so people need to accurately grasp the health status of the battery pack during its operation. The English expression of battery health status is State of health, referred to as SOH. Battery SOH characterizes the current battery's ability to store and release electrical energy relative to a new battery. It expresses the state of the battery from the beginning to the end of its life in the form of a percentage, which is used to quantitatively describe the current battery performance status. There are many performance indicators of batteries. There are many definitions of SOH at home and abroad, and there is a lack of unity in the concept. The current definition of SOH is mainly reflected in several aspects such as capacity, power, internal resistance, number of cycles and peak power. For example, when defined by capacity, SOH is the ratio of the current capacity of the battery to the rated capacity of the battery.
在实际的用户使用过程中，关于电池SOH的准确测试存在较大的技术难度：从容量和电量角度来说，需要对电池进行完全的充放电测试，但用户使用过程很少对电池进行完全的充放电；从内阻的角度来说，需要用专门的精密仪器和测试方法才能准确测量电池的内阻，而普通用户使用过程中显然不存在这种条件；从循环次数的角度来说，实际使用过程电池很少在固定的初始荷电态和终止荷电态之间发生充放电循环；从峰值功率的角度来说，需要在使用过程按照固定的充放电电流和时长进行电池的充放电，且需要达到极限的充放电电流值以便获得峰值功率，这不但干扰用户的正常使用，而且频繁的大电流充放电对电池自身寿命造成不利影响。因此，需要在不干扰用户正常使用、不需要特殊专门的仪器和测试方法且不对电池自身造成伤害的情况下，提出新的电池包健康状态评估方法。In actual user use, there are great technical difficulties in accurately testing the battery SOH: from the perspective of capacity and power, the battery needs to be fully charged and discharged, but users rarely fully charge and discharge the battery during use; from the perspective of internal resistance, special precision instruments and test methods are required to accurately measure the internal resistance of the battery, but this condition obviously does not exist during ordinary user use; from the perspective of the number of cycles, the battery rarely undergoes a charge and discharge cycle between a fixed initial state of charge and a terminal state of charge during actual use; from the perspective of peak power, the battery needs to be charged and discharged at a fixed charge and discharge current and duration during use, and the limit charge and discharge current value needs to be reached in order to obtain peak power, which not only interferes with the normal use of the user, but also the frequent high-current charge and discharge has an adverse effect on the battery's own life. Therefore, it is necessary to propose a new battery pack health status assessment method without interfering with the normal use of the user, without requiring special instruments and test methods, and without causing damage to the battery itself.
发明内容Summary of the invention
为了解决上述技术问题，本发明提供一种实施简单方便、通用性好、准确度和可靠度高的液冷式电池包健康状态评估方法。In order to solve the above technical problems, the present invention provides a liquid-cooled battery pack health status assessment method which is simple and convenient to implement, has good versatility, and has high accuracy and reliability.
本发明解决上述问题的技术方案是：一种液冷式电池包健康状态评估方法，所述电池包通过与之紧贴的液冷板散热且所述液冷板内流经有冷却液，电池包厂商事先分别对寿命起始点和寿命终止点的电池包样品进行若干不同环境温度下吸热率的测试标定，获得不同环境温度下电池包自完全放电态向满电态充电全过程液冷板的总吸热量Q和电池包的充电量W并计算二者之比以得到吸热率k：The technical solution of the present invention to solve the above problem is: a method for evaluating the health status of a liquid-cooled battery pack, wherein the battery pack dissipates heat through a liquid cooling plate in close contact with the battery pack and a coolant flows through the liquid cooling plate. The battery pack manufacturer performs heat absorption rate test calibration on battery pack samples at the start point and end point of the life in advance at several different ambient temperatures, obtains the total heat absorption Q of the liquid cooling plate and the charge W of the battery pack during the whole process of charging the battery pack from a fully discharged state to a fully charged state at different ambient temperatures, and calculates the ratio of the two to obtain the heat absorption rate k:
k＝Q/W (1)k=Q/W (1)
式中Q为某个指定的环境温度下电池包自完全放电态向满电态充电全过程液冷板的总吸热量，W为某个指定的环境温度下电池包自完全放电态向满电态充电全过程电池包的充电量，k为某个指定的环境温度下的吸热率；Where Q is the total heat absorbed by the liquid cooling plate during the whole process of charging the battery pack from a fully discharged state to a fully charged state at a certain specified ambient temperature, W is the charge amount of the battery pack during the whole process of charging the battery pack from a fully discharged state to a fully charged state at a certain specified ambient temperature, and k is the heat absorption rate at a certain specified ambient temperature;
通过以上测试标定，获得寿命起始点电池包样品的多个环境温度及与之一一对应的吸热率k值并由此构成第一数据表格，获得寿命终止点电池包样品的多个环境温度及与之一一对应的吸热率k值并由此构成第二数据表格；Through the above test calibration, multiple ambient temperatures of the battery pack samples at the start of life and the corresponding heat absorption rate k values are obtained to form a first data table, and multiple ambient temperatures of the battery pack samples at the end of life and the corresponding heat absorption rate k values are obtained to form a second data table;
电池包产品出厂后的使用过程中，对于每一次充电过程，按以下步骤计算电池包健康状态SOHi：During the use of the battery pack product after leaving the factory, for each charging process, the battery pack health status SOH i is calculated according to the following steps:
步骤1、记录当次充电过程的环境温度平均值，统计当次充电过程液冷板的总吸热量和电池包的充电量，并将总吸热量除以充电量以得到电池包的吸热率ki；Step 1, record the average value of the ambient temperature during the charging process, calculate the total heat absorption of the liquid cooling plate and the charge amount of the battery pack during the charging process, and divide the total heat absorption by the charge amount to obtain the heat absorption rate k i of the battery pack;
步骤2、从第一数据表格中查询与当次充电过程的环境平均值温度最为接近的两个环境温度值及二者对应的吸热率值，通过线性插值方式获得寿命起始点电池包样品在当次充电过程的环境温度平均值下的吸热率kb；Step 2: query the two ambient temperature values closest to the average ambient temperature of the current charging process and the corresponding heat absorption rate values from the first data table, and obtain the heat absorption rate k b of the battery pack sample at the starting point of life under the average ambient temperature of the current charging process by linear interpolation;
步骤3、从第二数据表格中查询与当次充电过程的环境平均值温度最为接近的两个环境温度值及二者对应的吸热率值，通过线性插值方式获得寿命终止点电池包样品在当次充电过程的环境温度平均值下的吸热率ke；Step 3, querying two ambient temperature values closest to the average ambient temperature of the current charging process and the corresponding heat absorption rate values from the second data table, and obtaining the heat absorption rate k e of the end-of-life battery pack sample under the average ambient temperature of the current charging process by linear interpolation;
步骤4、由当次充电过程获得的数据计算电池包健康状态SOHi并予以存储：Step 4: Calculate the battery pack health status SOH i from the data obtained during the current charging process and store it:
SOHi＝100％×(ke-ki)/(ke-kb) (2)SOH i =100%×(k e -k i )/(k e -k b ) (2)
式中，SOHi为当次充电过程对应的电池包健康状态，ke为步骤B3获得的寿命终止点电池包样品在当次充电过程的环境温度平均值下的吸热率，kb为步骤B2获得的寿命起始点电池包样品在当次充电过程的环境温度平均值下的吸热率，ki为步骤B1获得的当次充电过程电池包的吸热率；Wherein, SOH i is the health status of the battery pack corresponding to the current charging process, ke is the heat absorption rate of the battery pack sample at the end of life obtained in step B3 under the average ambient temperature of the current charging process, kb is the heat absorption rate of the battery pack sample at the start of life obtained in step B2 under the average ambient temperature of the current charging process, and k i is the heat absorption rate of the battery pack in the current charging process obtained in step B1;
作为本发明技术方案的进一步改进，步骤4计算出来的SOHi须处于0％至100％之间，由于实际应用场合不排除出现特殊情况以及测量误差，故对式(2)的计算结果进行校正后再予以存储：若计算出来的SOHi小于0％，则将其校正为0％；若计算出来的SOHi大于100％，则将其校正为100％。As a further improvement of the technical solution of the present invention, the SOH i calculated in step 4 must be between 0% and 100%. Since special circumstances and measurement errors may occur in actual applications, the calculation result of formula (2) is corrected before being stored: if the calculated SOH i is less than 0%, it is corrected to 0%; if the calculated SOH i is greater than 100%, it is corrected to 100%.
对电池包产品出厂后使用的任意某个时刻，若存储的SOHi计算结果记录大于或等于N次，则计算最近的N次SOHi计算结果的平均值并作为最终健康状态输出至用户；若存储的SOHi计算结果记录小于N次，则计算存储的所有SOHi计算结果的平均值并作为最终健康状态输出至用户，其中N为正整数。At any time when the battery pack product is used after leaving the factory, if the stored SOH i calculation result records are greater than or equal to N times, the average of the most recent N SOH i calculation results is calculated and output to the user as the final health status; if the stored SOH i calculation result records are less than N times, the average of all stored SOH i calculation results is calculated and output to the user as the final health status, where N is a positive integer.
上述液冷式电池包健康状态评估方法，所述分别对寿命起始点和寿命终止点的电池包样品进行若干不同环境温度下吸热率的测试标定，其中若干不同环境温度值为以电池包最低许可充电环境温度为首项、以电池包最高许可充电环境温度为末项且项数大于5的等差数列。In the above-mentioned liquid-cooled battery pack health status assessment method, the heat absorption rate of the battery pack samples at the starting point and the end point of the life are tested and calibrated at several different ambient temperatures, wherein the several different ambient temperature values are an arithmetic progression with the lowest allowable charging ambient temperature of the battery pack as the first item and the highest allowable charging ambient temperature of the battery pack as the last item, and the number of items is greater than 5.
上述液冷式电池包健康状态评估方法，所述正整数N的取值处于5至50之间。In the above-mentioned liquid-cooled battery pack health status assessment method, the value of the positive integer N is between 5 and 50.
上述液冷式电池包健康状态评估方法，所述充电过程液冷板的总吸热量为充电过程流经液冷板的冷却液的平均流量、流经液冷板的冷却液的平均温差、充电过程时长和冷却液比热容这四者之积，其中流经液冷板的冷却液的平均温差为流出液冷板的冷却液温度平均值与流入液冷板的冷却液温度平均值之差。In the above-mentioned method for evaluating the health status of a liquid-cooled battery pack, the total heat absorbed by the liquid cooling plate during the charging process is the product of the average flow rate of the coolant flowing through the liquid cooling plate during the charging process, the average temperature difference of the coolant flowing through the liquid cooling plate, the duration of the charging process, and the specific heat capacity of the coolant, wherein the average temperature difference of the coolant flowing through the liquid cooling plate is the difference between the average temperature of the coolant flowing out of the liquid cooling plate and the average temperature of the coolant flowing into the liquid cooling plate.
上述液冷式电池包健康状态评估方法，所述电池包的充电量为充电过程充电装置向电池包提供的总电能且可通过电池包的充电装置获得其值。In the above-mentioned liquid-cooled battery pack health status assessment method, the charge capacity of the battery pack is the total electrical energy provided to the battery pack by the charging device during the charging process and its value can be obtained through the charging device of the battery pack.
上述液冷式电池包健康状态评估方法，所述电池包厂商对吸热率的测试标定过程中寿命起始点的电池包样品，为刚出厂状态时的电池包。In the above-mentioned liquid-cooled battery pack health status assessment method, the battery pack sample at the starting point of life in the process of heat absorption rate testing and calibration by the battery pack manufacturer is the battery pack in the factory state.
上述液冷式电池包健康状态评估方法，所述电池包厂商对吸热率的测试标定过程中寿命终止点的电池包样品，其获取方法为，通过对电池包样品进行加速寿命试验使其达到电池包厂商规定的寿命终止状态。In the above-mentioned liquid-cooled battery pack health status assessment method, the battery pack manufacturer obtains the battery pack samples at the end-of-life point in the test calibration process of the heat absorption rate by performing an accelerated life test on the battery pack samples to make them reach the end-of-life state specified by the battery pack manufacturer.
上述液冷式电池包健康状态评估方法，所述电池包厂商对吸热率的测试标定过程中不同环境温度下电池包完全放电态，其获得方法为，先将电池包于室温下搁置1小时以上并以0.01C至0.5C倍率恒流放电至电池包的放电截止电压，然后再将电池包转移至测试指定的环境温度下并搁置1小时以上。The above-mentioned liquid-cooled battery pack health status assessment method, the battery pack manufacturer's test calibration process of the heat absorption rate, the battery pack fully discharged state at different ambient temperatures, the method of obtaining the method is, first leave the battery pack at room temperature for more than 1 hour and discharge it at a constant current rate of 0.01C to 0.5C to the discharge cut-off voltage of the battery pack, and then transfer the battery pack to the ambient temperature specified for the test and leave it for more than 1 hour.
上述液冷式电池包健康状态评估方法，所述电池包厂商对吸热率的测试标定过程中电池包自完全放电态向满电态充电，为将电池包在测试指定的环境温度下自完全放电态开始以0.01C至1C倍率恒流充电至电池包的充电截止电压。In the above-mentioned liquid-cooled battery pack health status assessment method, the battery pack manufacturer charges the battery pack from a fully discharged state to a fully charged state during the test calibration of the heat absorption rate, which is to charge the battery pack from a fully discharged state at a constant current rate of 0.01C to 1C at the ambient temperature specified in the test to the charging cut-off voltage of the battery pack.
上述液冷式电池包健康状态评估方法，所述充电过程流经液冷板的冷却液的平均流量为充电过程各时刻流经液冷板的冷却液的流量值的平均值，其中各时刻流经液冷板的冷却液的流量值由以下方式获得：若充电过程流经液冷板的流量值始终恒定，则通过查阅电池包设计资料获得该流量值；若充电过程流经液冷板的流量值不恒定，则采取以下三种方式中的任意一种获得各时刻的流量值：In the above-mentioned liquid-cooled battery pack health status assessment method, the average flow rate of the coolant flowing through the liquid cooling plate during the charging process is the average value of the flow rate value of the coolant flowing through the liquid cooling plate at each moment of the charging process, wherein the flow rate value of the coolant flowing through the liquid cooling plate at each moment is obtained by the following method: if the flow rate value of the coolant flowing through the liquid cooling plate during the charging process is always constant, the flow rate value is obtained by referring to the battery pack design data; if the flow rate value of the coolant flowing through the liquid cooling plate during the charging process is not constant, any one of the following three methods is adopted to obtain the flow rate value at each moment:
(i)通过在与液冷板连通的冷却液输送管路中安装流量计来测量流量值；(i) measuring the flow value by installing a flow meter in the coolant delivery pipeline connected to the liquid cooling plate;
(ii)通过测量液冷板进出口之间的压差ΔP并通过计算来获得流量值：(ii) The flow rate is obtained by measuring the pressure difference ΔP between the inlet and outlet of the liquid cooling plate and calculating:
式中，q为通过液冷板的冷却液的流量值，ΔP为测量获得的液冷板进出和出口之间的压力差，ξ为液冷板内流道的阻力系数；Where q is the flow rate of the coolant passing through the liquid cooling plate, ΔP is the measured pressure difference between the inlet and outlet of the liquid cooling plate, and ξ is the resistance coefficient of the flow channel in the liquid cooling plate;
(iii)通过测量为冷却液流动提供动力的离心泵的转速并查表来获得流量值：事先对包含液冷板的液冷管路进行测试标定，测量不同离心泵转速值所对应的通过液冷板的冷却液的流量值并构成数据表格；测量离心泵的当前转速值并从数据表格中寻找与测量得到的转速值最接近的两个转速值及其对应的流量值，并通过线性插值的方式获得当前流量值。(iii) obtaining a flow value by measuring the rotation speed of a centrifugal pump that provides power for the flow of the coolant and looking up the table: testing and calibrating the liquid cooling pipeline including the liquid cooling plate in advance, measuring the flow values of the coolant passing through the liquid cooling plate corresponding to different rotation speed values of the centrifugal pump and forming a data table; measuring the current rotation speed value of the centrifugal pump and searching the data table for the two rotation speed values closest to the measured rotation speed value and their corresponding flow values, and obtaining the current flow value by linear interpolation.
本发明的有益效果在于：The beneficial effects of the present invention are:
1、本发明参照现有的以电池内阻变化作为健康状态定量评估指标的通行做法，利用电池内阻增大则产热量增大且充电效率下降的原理，并近似将液冷板的吸热量等同为电池产热量，在此基础上使用充电全过程液冷板的总吸热量和电池包的充电量的比值以得到吸热率指标，通过分析电池使用过程吸热量的变化情况来衡量健康状态。这种方法科学合理，本质上还是评估电池使用过程的内阻变化情况；但是实际应用起来，只需在原来的电池包基础上增设液冷板进出口处的温度传感器和环境温度传感器并对进出口冷却液温差进行统计，而不需要精密的内阻测量仪器或专门的测量手段，不干扰电池包的正常使用，也不对电池包带来任何负面影响，因此该方法实施简单方便、通用性好。1. The present invention refers to the existing common practice of using the change of battery internal resistance as a quantitative evaluation indicator of health status, and uses the principle that the increase of battery internal resistance will increase the heat generation and reduce the charging efficiency, and approximately equates the heat absorption of the liquid cooling plate with the heat generation of the battery. On this basis, the ratio of the total heat absorption of the liquid cooling plate during the entire charging process and the charging amount of the battery pack is used to obtain the heat absorption rate index, and the health status is measured by analyzing the change of heat absorption during the use of the battery. This method is scientific and reasonable, and in essence it still evaluates the change of internal resistance during the use of the battery; however, in actual application, it only needs to add temperature sensors and ambient temperature sensors at the inlet and outlet of the liquid cooling plate on the basis of the original battery pack and count the temperature difference of the inlet and outlet coolant, without the need for precise internal resistance measuring instruments or special measuring means, and does not interfere with the normal use of the battery pack, nor does it bring any negative impact on the battery pack. Therefore, this method is simple and convenient to implement and has good versatility.
2、考虑到电池包每次充电量并不相同，且充电时环境温度也会对电池包内阻造成影响，进而不同的环境温度下充电过程的产热量也存在差别，故使用不同环境温度下充电全过程液冷板的总吸热量和电池包的充电量的比值以得到吸热率指标，这种吸热率值是一个与温度相关的相对值。每次充电时记录当次充电过程环境温度平均值及其对应的当前吸热率值，并通过查表估算得到当次充电过程环境温度平均值所对应的寿命起始点和寿命终止点时电池包的吸热量值，用于健康状态的计算；最后通过健康状态的校正和统计修正方法来排除错误和偏差，故这种健康状态评估的准确度和可靠度高。2. Considering that the charging amount of the battery pack is not the same each time, and the ambient temperature during charging will also affect the internal resistance of the battery pack, and thus the heat generation during the charging process at different ambient temperatures is also different, the total heat absorption of the liquid cooling plate during the entire charging process at different ambient temperatures and the charging amount of the battery pack are used to obtain the heat absorption rate index. This heat absorption rate value is a relative value related to temperature. Each time charging is performed, the average ambient temperature of the charging process and its corresponding current heat absorption rate value are recorded, and the heat absorption value of the battery pack at the life start point and life end point corresponding to the average ambient temperature of the charging process is estimated by looking up the table, which is used for the calculation of the health status; finally, errors and deviations are eliminated through the correction and statistical correction methods of the health status, so the accuracy and reliability of this health status assessment are high.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
图1为本发明实施例中液冷式电池包健康状态评估方法的流程图。FIG1 is a flow chart of a method for evaluating the health status of a liquid-cooled battery pack according to an embodiment of the present invention.
图2为本发明实施例中液冷式电池包及其液冷管路系统的结构示意图，图中1为离心泵，2为定速电机，3为膨胀水箱，4为第一换热器，5为电池包，6为第二换热器，7为第一温度传感器、8为第二温度传感器、9为第三温度传感器、10为信息处理模块、11为行车电脑。Figure 2 is a schematic diagram of the structure of a liquid-cooled battery pack and its liquid cooling piping system in an embodiment of the present invention, in which 1 is a centrifugal pump, 2 is a constant speed motor, 3 is an expansion water tank, 4 is a first heat exchanger, 5 is a battery pack, 6 is a second heat exchanger, 7 is a first temperature sensor, 8 is a second temperature sensor, 9 is a third temperature sensor, 10 is an information processing module, and 11 is a driving computer.
具体实施方式DETAILED DESCRIPTION
下面结合附图和实施例对本发明作进一步的说明。The present invention will be further described below in conjunction with the accompanying drawings and embodiments.
如图1所示，一种液冷式电池包健康状态评估方法，所述电池包通过与之紧贴的液冷板散热且所述液冷板内流经有冷却液，电池包厂商事先分别对寿命起始点和寿命终止点的电池包样品进行若干不同环境温度下吸热率的测试标定，获得不同环境温度下电池包自完全放电态向满电态充电全过程液冷板的总吸热量Q和电池包的充电量W并计算二者之比以得到吸热率k：As shown in FIG1 , a method for evaluating the health status of a liquid-cooled battery pack is provided. The battery pack dissipates heat through a liquid cooling plate that is in close contact with the battery pack and a coolant flows through the liquid cooling plate. The battery pack manufacturer calibrates the heat absorption rate of the battery pack samples at the start and end of life at several different ambient temperatures in advance, obtains the total heat absorption Q of the liquid cooling plate and the charge W of the battery pack during the whole process of charging the battery pack from a fully discharged state to a fully charged state at different ambient temperatures, and calculates the ratio of the two to obtain the heat absorption rate k:
k＝Q/W (1)k=Q/W (1)
式中Q为某个指定的环境温度下电池包自完全放电态向满电态充电全过程液冷板的总吸热量，W为某个指定的环境温度下电池包自完全放电态向满电态充电全过程电池包的充电量，k为某个指定的环境温度下的吸热率；Where Q is the total heat absorbed by the liquid cooling plate during the whole process of charging the battery pack from a fully discharged state to a fully charged state at a certain specified ambient temperature, W is the charge amount of the battery pack during the whole process of charging the battery pack from a fully discharged state to a fully charged state at a certain specified ambient temperature, and k is the heat absorption rate at a certain specified ambient temperature;
通过以上测试标定，获得寿命起始点电池包样品的多个环境温度及与之一一对应的吸热率k值并由此构成第一数据表格，获得寿命终止点电池包样品的多个环境温度及与之一一对应的吸热率k值并由此构成第二数据表格；Through the above test calibration, multiple ambient temperatures of the battery pack samples at the start of life and the corresponding heat absorption rate k values are obtained to form a first data table, and multiple ambient temperatures of the battery pack samples at the end of life and the corresponding heat absorption rate k values are obtained to form a second data table;
电池包产品出厂后的使用过程中，对于每一次充电过程，按以下步骤计算电池包健康状态SOHi：During the use of the battery pack product after leaving the factory, for each charging process, the battery pack health status SOH i is calculated according to the following steps:
步骤1、记录当次充电过程的环境温度平均值，统计当次充电过程液冷板的总吸热量和电池包的充电量，并将总吸热量除以充电量以得到电池包的吸热率ki；Step 1, record the average value of the ambient temperature during the charging process, calculate the total heat absorption of the liquid cooling plate and the charge amount of the battery pack during the charging process, and divide the total heat absorption by the charge amount to obtain the heat absorption rate k i of the battery pack;
步骤2、从第一数据表格中查询与当次充电过程的环境平均值温度最为接近的两个环境温度值及二者对应的吸热率值，通过线性插值方式获得寿命起始点电池包样品在当次充电过程的环境温度平均值下的吸热率kb；Step 2: query the two ambient temperature values closest to the average ambient temperature of the current charging process and the corresponding heat absorption rate values from the first data table, and obtain the heat absorption rate k b of the battery pack sample at the starting point of life under the average ambient temperature of the current charging process by linear interpolation;
步骤3、从第二数据表格中查询与当次充电过程的环境平均值温度最为接近的两个环境温度值及二者对应的吸热率值，通过线性插值方式获得寿命终止点电池包样品在当次充电过程的环境温度平均值下的吸热率ke；Step 3, querying two ambient temperature values closest to the average ambient temperature of the current charging process and the corresponding heat absorption rate values from the second data table, and obtaining the heat absorption rate k e of the end-of-life battery pack sample under the average ambient temperature of the current charging process by linear interpolation;
步骤4、由当次充电过程获得的数据计算电池包健康状态SOHi并予以存储：Step 4: Calculate the battery pack health status SOH i from the data obtained during the current charging process and store it:
SOHi＝100％×(ke-ki)/(ke-kb) (2)SOH i =100%×(k e -k i )/(k e -k b ) (2)
式中，SOHi为当次充电过程对应的电池包健康状态，ke为步骤B3获得的寿命终止点电池包样品在当次充电过程的环境温度平均值下的吸热率，kb为步骤B2获得的寿命起始点电池包样品在当次充电过程的环境温度平均值下的吸热率，ki为步骤B1获得的当次充电过程电池包的吸热率；Wherein, SOH i is the health status of the battery pack corresponding to the current charging process, ke is the heat absorption rate of the battery pack sample at the end of life obtained in step B3 under the average ambient temperature of the current charging process, kb is the heat absorption rate of the battery pack sample at the start of life obtained in step B2 under the average ambient temperature of the current charging process, and k i is the heat absorption rate of the battery pack in the current charging process obtained in step B1;
作为本发明技术方案的进一步改进，步骤4计算出来的SOHi须处于0％至100％之间，由于实际应用场合不排除出现特殊情况以及测量误差，故对式(2)的计算结果进行校正后再予以存储：若计算出来的SOHi小于0％，则将其校正为0％；若计算出来的SOHi大于100％，则将其校正为100％。As a further improvement of the technical solution of the present invention, the SOH i calculated in step 4 must be between 0% and 100%. Since special circumstances and measurement errors may occur in actual applications, the calculation result of formula (2) is corrected before being stored: if the calculated SOH i is less than 0%, it is corrected to 0%; if the calculated SOH i is greater than 100%, it is corrected to 100%.
对电池包产品出厂后使用的任意某个时刻，若存储的SOHi计算结果记录大于或等于N次，则计算最近的N次SOHi计算结果的平均值并作为最终健康状态输出至用户；若存储的SOHi计算结果记录小于N次，则计算存储的所有SOHi计算结果的平均值并作为最终健康状态输出至用户，其中N为正整数。At any time when the battery pack product is used after leaving the factory, if the stored SOH i calculation result records are greater than or equal to N times, the average of the most recent N SOH i calculation results is calculated and output to the user as the final health status; if the stored SOH i calculation result records are less than N times, the average of all stored SOH i calculation results is calculated and output to the user as the final health status, where N is a positive integer.
上述液冷式电池包健康状态评估方法，所述分别对寿命起始点和寿命终止点的电池包样品进行若干不同环境温度下吸热率的测试标定，其中若干不同环境温度值为以电池包最低许可充电环境温度为首项、以电池包最高许可充电环境温度为末项且项数大于5的等差数列。In the above-mentioned liquid-cooled battery pack health status assessment method, the heat absorption rate of the battery pack samples at the starting point and the end point of the life are tested and calibrated at several different ambient temperatures, wherein the several different ambient temperature values are an arithmetic progression with the lowest allowable charging ambient temperature of the battery pack as the first item and the highest allowable charging ambient temperature of the battery pack as the last item, and the number of items is greater than 5.
上述液冷式电池包健康状态评估方法，所述正整数N的取值处于5至50之间。In the above-mentioned liquid-cooled battery pack health status assessment method, the value of the positive integer N is between 5 and 50.
上述液冷式电池包健康状态评估方法，所述充电过程液冷板的总吸热量为充电过程流经液冷板的冷却液的平均流量、流经液冷板的冷却液的平均温差、充电过程时长和冷却液比热容这四者之积，其中流经液冷板的冷却液的平均温差为流出液冷板的冷却液温度平均值与流入液冷板的冷却液温度平均值之差。In the above-mentioned method for evaluating the health status of a liquid-cooled battery pack, the total heat absorbed by the liquid cooling plate during the charging process is the product of the average flow rate of the coolant flowing through the liquid cooling plate during the charging process, the average temperature difference of the coolant flowing through the liquid cooling plate, the duration of the charging process, and the specific heat capacity of the coolant, wherein the average temperature difference of the coolant flowing through the liquid cooling plate is the difference between the average temperature of the coolant flowing out of the liquid cooling plate and the average temperature of the coolant flowing into the liquid cooling plate.
上述液冷式电池包健康状态评估方法，所述电池包的充电量为充电过程充电装置向电池包提供的总电能且可通过电池包的充电装置获得其值。In the above-mentioned liquid-cooled battery pack health status assessment method, the charge capacity of the battery pack is the total electrical energy provided to the battery pack by the charging device during the charging process and its value can be obtained through the charging device of the battery pack.
上述液冷式电池包健康状态评估方法，所述电池包厂商对吸热率的测试标定过程中寿命起始点的电池包样品，为刚出厂状态时的电池包。In the above-mentioned liquid-cooled battery pack health status assessment method, the battery pack sample at the starting point of life in the process of heat absorption rate testing and calibration by the battery pack manufacturer is the battery pack in the factory state.
上述液冷式电池包健康状态评估方法，所述电池包厂商对吸热率的测试标定过程中寿命终止点的电池包样品，其获取方法为，通过对电池包样品进行加速寿命试验使其达到电池包厂商规定的寿命终止状态。In the above-mentioned liquid-cooled battery pack health status assessment method, the battery pack manufacturer obtains the battery pack samples at the end-of-life point in the test calibration process of the heat absorption rate by performing an accelerated life test on the battery pack samples to make them reach the end-of-life state specified by the battery pack manufacturer.
上述液冷式电池包健康状态评估方法，所述电池包厂商对吸热率的测试标定过程中不同环境温度下电池包完全放电态，其获得方法为，先将电池包于室温下搁置1小时以上并以0.01C至0.5C倍率恒流放电至电池包的放电截止电压，然后再将电池包转移至测试指定的环境温度下并搁置1小时以上。The above-mentioned liquid-cooled battery pack health status assessment method, the battery pack manufacturer's test calibration process of the heat absorption rate, the battery pack fully discharged state at different ambient temperatures, the method of obtaining the method is, first leave the battery pack at room temperature for more than 1 hour and discharge it at a constant current rate of 0.01C to 0.5C to the discharge cut-off voltage of the battery pack, and then transfer the battery pack to the ambient temperature specified for the test and leave it for more than 1 hour.
上述液冷式电池包健康状态评估方法，所述电池包厂商对吸热率的测试标定过程中电池包自完全放电态向满电态充电，为将电池包在测试指定的环境温度下自完全放电态开始以0.01C至1C倍率恒流充电至电池包的充电截止电压。In the above-mentioned liquid-cooled battery pack health status assessment method, the battery pack manufacturer charges the battery pack from a fully discharged state to a fully charged state during the test calibration of the heat absorption rate, which is to charge the battery pack from a fully discharged state at a constant current rate of 0.01C to 1C at the ambient temperature specified in the test to the charging cut-off voltage of the battery pack.
上述液冷式电池包健康状态评估方法，所述充电过程流经液冷板的冷却液的平均流量为充电过程各时刻流经液冷板的冷却液的流量值的平均值，其中各时刻流经液冷板的冷却液的流量值由以下方式获得：若充电过程流经液冷板的流量值始终恒定，则通过查阅电池包设计资料获得该流量值；若充电过程流经液冷板的流量值不恒定，则采取以下三种方式中的任意一种获得各时刻的流量值：In the above-mentioned liquid-cooled battery pack health status assessment method, the average flow rate of the coolant flowing through the liquid cooling plate during the charging process is the average value of the flow rate value of the coolant flowing through the liquid cooling plate at each moment of the charging process, wherein the flow rate value of the coolant flowing through the liquid cooling plate at each moment is obtained by the following method: if the flow rate value of the coolant flowing through the liquid cooling plate during the charging process is always constant, the flow rate value is obtained by referring to the battery pack design data; if the flow rate value of the coolant flowing through the liquid cooling plate during the charging process is not constant, any one of the following three methods is adopted to obtain the flow rate value at each moment:
(i)通过在与液冷板连通的冷却液输送管路中安装流量计来测量流量值；(i) measuring the flow value by installing a flow meter in the coolant delivery pipeline connected to the liquid cooling plate;
(ii)通过测量液冷板进出口之间的压差ΔP并通过计算来获得流量值：(ii) The flow rate is obtained by measuring the pressure difference ΔP between the inlet and outlet of the liquid cooling plate and calculating:
式中，q为通过液冷板的冷却液的流量值，ΔP为测量获得的液冷板进出和出口之间的压力差，ξ为液冷板内流道的阻力系数；Where q is the flow rate of the coolant passing through the liquid cooling plate, ΔP is the measured pressure difference between the inlet and outlet of the liquid cooling plate, and ξ is the resistance coefficient of the flow channel in the liquid cooling plate;
(iii)通过测量为冷却液流动提供动力的离心泵的转速并查表来获得流量值：事先对包含液冷板的液冷管路进行测试标定，测量不同离心泵转速值所对应的通过液冷板的冷却液的流量值并构成数据表格；测量离心泵的当前转速值并从数据表格中寻找与测量得到的转速值最接近的两个转速值及其对应的流量值，并通过线性插值的方式获得当前流量值。(iii) obtaining a flow value by measuring the rotation speed of a centrifugal pump that provides power for the flow of the coolant and looking up the table: testing and calibrating the liquid cooling pipeline including the liquid cooling plate in advance, measuring the flow values of the coolant passing through the liquid cooling plate corresponding to different rotation speed values of the centrifugal pump and forming a data table; measuring the current rotation speed value of the centrifugal pump and searching the data table for the two rotation speed values closest to the measured rotation speed value and their corresponding flow values, and obtaining the current flow value by linear interpolation.
实施例Example
某纯电动汽车电池包的电池为锂离子动力电池，其组成为1并94串，电池包的额定容量150Ah，额定电压300V，充、放电截至电压分别为345V、235V，使用液冷方式进行电池包的热管理，冷却液为比热容为3.8kJ/kg·℃的乙二醇水溶液，其液冷管路系统可参见图2。The battery of a pure electric vehicle battery pack is a lithium-ion power battery, which consists of 1 parallel and 94 series. The rated capacity of the battery pack is 150Ah, the rated voltage is 300V, and the charge and discharge cut-off voltages are 345V and 235V respectively. Liquid cooling is used for thermal management of the battery pack. The coolant is an ethylene glycol aqueous solution with a specific heat capacity of 3.8kJ/kg·℃. The liquid cooling pipeline system can be seen in Figure 2.
如图2所示，该电池包液冷系统包括离心泵1、与离心泵1机械连接且用于驱动离心泵1运转的定速电机2、膨胀水箱3、第一换热器4和第二换热器6，所述离心泵1、膨胀水箱3、第一换热器4和第二换热器6通过管道依次连接且第二换热器6与离心泵1通过管道连接，第一换热器4与电池包5紧贴并借助流经第一换热器4的冷却液来实现电池包5的冷却，第二换热器6用于冷却液的降温冷却；为了实现该电池包健康状态评估，增设置于第一换热器4进口处的第一温度传感器7，置于第一换热器4出口处的第二温度传感器8，用于采集电动汽车外界环境温度的第三温度传感器9，与第一温度传感器7、第二温度传感器8和第三温度传感器9电性连接的信息处理模块10；第一温度传感器7用于采集流入第一换热器4的冷却液的温度，第二温度传感器8温度传感器用于采集流出第一换热器4的冷却液的温度，信息处理模块10还与行车电脑11电性连接。相关数据的统计分析和计算由信息处理模块进行。As shown in FIG2 , the battery pack liquid cooling system includes a centrifugal pump 1, a constant speed motor 2 mechanically connected to the centrifugal pump 1 and used to drive the centrifugal pump 1 to operate, an expansion water tank 3, a first heat exchanger 4 and a second heat exchanger 6. The centrifugal pump 1, the expansion water tank 3, the first heat exchanger 4 and the second heat exchanger 6 are sequentially connected by pipelines, and the second heat exchanger 6 is connected to the centrifugal pump 1 by a pipeline. The first heat exchanger 4 is in close contact with the battery pack 5 and cools the battery pack 5 with the help of the coolant flowing through the first heat exchanger 4. The second heat exchanger 6 is used to cool the coolant. In order to achieve the health status assessment of the battery pack , a first temperature sensor 7 is added at the inlet of the first heat exchanger 4, a second temperature sensor 8 is placed at the outlet of the first heat exchanger 4, a third temperature sensor 9 is used to collect the external environment temperature of the electric vehicle, and an information processing module 10 is electrically connected to the first temperature sensor 7, the second temperature sensor 8 and the third temperature sensor 9; the first temperature sensor 7 is used to collect the temperature of the coolant flowing into the first heat exchanger 4, the second temperature sensor 8 is used to collect the temperature of the coolant flowing out of the first heat exchanger 4, and the information processing module 10 is also electrically connected to the driving computer 11. The statistical analysis and calculation of relevant data are performed by the information processing module.
由于离心泵1转速不变，工作过程冷却液的流量不变，其通过第一换热器4的质量流量恒定为0.3kg/s。Since the rotation speed of the centrifugal pump 1 remains unchanged, the flow rate of the coolant remains unchanged during the working process, and the mass flow rate of the coolant passing through the first heat exchanger 4 is constant at 0.3 kg/s.
随机挑选两个刚出厂状态的完好电池包样品进行吸热率测试标定。Two intact battery pack samples just out of the factory were randomly selected for heat absorption rate test and calibration.
首先，将其中一个电池包作为寿命起始点样品，而对另一个样品进行加速寿命试验，具体方法为将其置于55℃高温环境持续地进行“1C恒流充电至充电截止电压、搁置0.5小时、1C恒流放电至放电截止电压、搁置0.5小时”的循环，且每循环100次后将其转移至室温环境测试其容量，当室温环境容量衰减至额定容量80％以下时则认为该电池包样品达到寿命终止状态。First, one of the battery packs is taken as the sample at the starting point of its life, and the other sample is subjected to an accelerated life test. The specific method is to place it in a high temperature environment of 55°C and continuously perform a cycle of "1C constant current charging to the charging cut-off voltage, leaving it for 0.5 hours, 1C constant current discharging to the discharge cut-off voltage, leaving it for 0.5 hours", and after every 100 cycles, it is transferred to the room temperature environment to test its capacity. When the capacity in the room temperature environment decays to less than 80% of the rated capacity, the battery pack sample is considered to have reached the end of its life.
然后，分别对寿命起始点和寿命终止点的电池包样品进行若干不同环境温度下吸热率的测试标定，选取的环境温度取值分别为-5℃、5℃、15℃、25℃、35℃和45℃，获得寿命起始点电池包样品的多个环境温度及与之一一对应的吸热率k值并由此构成第一数据表格，见表1；获得寿命终止点电池包样品的多个环境温度及与之一一对应的吸热率k值并由此构成第二数据表格，见表2。Then, the heat absorption rate of the battery pack samples at the starting point and the end point of life were tested and calibrated at several different ambient temperatures. The selected ambient temperatures were -5°C, 5°C, 15°C, 25°C, 35°C and 45°C, respectively. Multiple ambient temperatures of the battery pack samples at the starting point of life and the corresponding heat absorption rate k values were obtained to form a first data table, see Table 1; multiple ambient temperatures of the battery pack samples at the end point of life and the corresponding heat absorption rate k values were obtained to form a second data table, see Table 2.
表1第一数据表格Table 1 First data table
表2第二数据表格Table 2 Second data table
电池包产品出厂后的使用过程中，以某一次耗时1小时的充电过程为例，按以下步骤计算电池包健康状态SOHi：During the use of the battery pack product after leaving the factory, taking a charging process that takes 1 hour as an example, the battery pack health status SOH i is calculated according to the following steps:
步骤1、通过第三温度传感器9记录统计当次充电过程的环境温度平均值为20℃，通过行车电脑11与充电装置进行通讯并获得电池包的充电量为10kWh，通过第一温度传感器7记录统计当次充电过程流入液冷板的冷却液的平均温度为15.2℃，流出液冷板的冷却液的平均温度为15.8℃，故当次充电过程流经液冷板的冷却液的平均温差为0.6℃，而冷却液的比热容为3.8kJ/kg·℃、质量流量为0.3kg/s，将充电过程流经液冷板的冷却液的平均流量、流经液冷板的冷却液的平均温差、充电过程时长和冷却液比热容这四者之相乘得到当次充电过程液冷板的总吸热量为0.684kWh，故将总吸热量0.684kWh除以充电量10kWh以得到电池包的吸热率ki＝0.0684。Step 1: The third temperature sensor 9 records and calculates that the average ambient temperature of the charging process is 20° C. The on-board computer 11 communicates with the charging device and obtains that the charging capacity of the battery pack is 10 kWh. The first temperature sensor 7 records and calculates that the average temperature of the coolant flowing into the liquid cooling plate during the charging process is 15.2° C., and the average temperature of the coolant flowing out of the liquid cooling plate is 15.8° C. Therefore, the average temperature difference of the coolant flowing through the liquid cooling plate during the charging process is 0.6° C., and the specific heat capacity of the coolant is 3.8 kJ/kg·° C., and the mass flow rate is 0.3 kg/s. The average flow rate of the coolant flowing through the liquid cooling plate during the charging process, the average temperature difference of the coolant flowing through the liquid cooling plate, the charging process duration, and the specific heat capacity of the coolant are multiplied to obtain a total heat absorption of the liquid cooling plate during the charging process of 0.684 kWh. Therefore, the total heat absorption of 0.684 kWh is divided by the charging capacity of 10 kWh to obtain the heat absorption rate of the battery pack k i =0.0684.
步骤2、从第一数据表格中查询与当次充电过程的环境平均值温度最为接近的两个环境温度值15℃和25℃，以及二者对应的吸热率值，通过线性插值方式获得寿命起始点电池包样品在当次充电过程的环境温度平均值即20℃下的吸热率kb＝0.0575。Step 2: Query the two ambient temperature values 15°C and 25°C that are closest to the average ambient temperature of the current charging process and their corresponding heat absorption rate values from the first data table, and obtain the heat absorption rate k b = 0.0575 of the battery pack sample at the average ambient temperature of the current charging process, i.e., 20°C, by linear interpolation.
步骤3、从第二数据表格中查询与当次充电过程的环境平均值温度最为接近的两个环境温度值15℃和25℃，以及二者对应的吸热率值，通过线性插值方式获得寿命终止点电池包样品在当次充电过程的环境温度平均值下的吸热率ke＝0.1015。Step 3: Query the two ambient temperature values 15°C and 25°C closest to the average ambient temperature of the current charging process and their corresponding heat absorption rate values from the second data table, and obtain the heat absorption rate ke = 0.1015 of the end-of-life battery pack sample at the average ambient temperature of the current charging process by linear interpolation.
步骤4、由当次充电过程获得的数据计算电池包健康状态SOHi并予以存储：SOHi＝100％×(ke-ki)/(ke-kb)＝(0.1015-0.0684)/(0.1015-0.0575)＝75％。本步骤计算得到的SOHi值处于0％至100％之间，无异常，故不需校正。Step 4: Calculate the battery pack health status SOH i from the data obtained during the current charging process and store it: SOH i = 100% × (ke - ki )/(ke - kb ) = (0.1015-0.0684)/(0.1015-0.0575) = 75%. The SOH i value calculated in this step is between 0% and 100%, and there is no abnormality, so no correction is required.
本实施例中正整数N取30。本次充电完毕后，信息处理模块10存储的SOHi计算结果记录大于30，则计算最近的30次SOHi计算结果的平均值为78％，最终输出至行车电脑11并显示给用户的电池包健康状态为78％。In this embodiment, the positive integer N is 30. After the current charging is completed, if the SOH i calculation result record stored in the information processing module 10 is greater than 30, the average value of the most recent 30 SOH i calculation results is calculated to be 78%, and the battery pack health status is finally output to the on-board computer 11 and displayed to the user as 78%.
本实施例提供的液冷式电池包健康状态评估方法，参照现有的以电池内阻变化作为健康状态定量评估指标的通行做法，利用电池内阻增大则产热量增大且充电效率下降的原理，并近似将液冷板的吸热量等同为电池产热量，在此基础上使用充电全过程液冷板的总吸热量和电池包的充电量的比值以得到吸热率指标，通过分析电池使用过程吸热量的变化情况来衡量健康状态。这种方法科学合理，本质上还是评估电池使用过程的内阻变化情况；但是实际应用起来，只需在原来的电池包基础上增设液冷板进出口处的温度传感器和环境温度传感器并对进出口冷却液温差进行统计，而不需要精密的内阻测量仪器或专门的测量手段，不干扰电池包的正常使用，也不对电池包带来任何负面影响，因此该方法实施简单方便、通用性好。The liquid-cooled battery pack health status assessment method provided in this embodiment refers to the existing common practice of using the change of battery internal resistance as a quantitative assessment indicator of health status, and uses the principle that the increase of battery internal resistance leads to the increase of heat generation and the decrease of charging efficiency, and approximately equates the heat absorption of the liquid cooling plate with the heat generation of the battery. On this basis, the ratio of the total heat absorption of the liquid cooling plate during the entire charging process and the charging amount of the battery pack is used to obtain the heat absorption rate index, and the health status is measured by analyzing the change of heat absorption during the use of the battery. This method is scientific and reasonable, and in essence it still evaluates the change of internal resistance during the use of the battery; however, in actual application, it only needs to add temperature sensors and ambient temperature sensors at the inlet and outlet of the liquid cooling plate on the basis of the original battery pack and count the temperature difference of the inlet and outlet coolant, without the need for precise internal resistance measuring instruments or special measuring means, and does not interfere with the normal use of the battery pack, nor does it bring any negative impact on the battery pack. Therefore, this method is simple and convenient to implement and has good versatility.
考虑到电池包每次充电量并不相同，且充电时环境温度也会对电池包内阻造成影响，进而不同的环境温度下充电过程的产热量也存在差别，故本实施例中使用不同环境温度下充电全过程液冷板的总吸热量和电池包的充电量的比值以得到吸热率指标，这种吸热率值是一个与温度相关的相对值。每次充电时记录当次充电过程环境温度平均值及其对应的当前吸热率值，并通过查表估算得到当次充电过程环境温度平均值所对应的寿命起始点和寿命终止点时电池包的吸热量值，用于健康状态的计算；最后通过健康状态的校正和统计修正方法来排除错误和偏差，故这种健康状态评估的准确度和可靠度高。Considering that the amount of charge of the battery pack is not the same each time, and the ambient temperature during charging will also affect the internal resistance of the battery pack, and thus the heat generation during the charging process at different ambient temperatures is also different, the total heat absorption of the liquid cooling plate during the entire charging process at different ambient temperatures and the charge amount of the battery pack are used in this embodiment to obtain the heat absorption rate index, which is a relative value related to temperature. Each time charging is performed, the average value of the ambient temperature of the charging process and its corresponding current heat absorption rate value are recorded, and the heat absorption value of the battery pack at the life start point and life end point corresponding to the average value of the ambient temperature of the charging process is estimated by looking up the table, which is used for the calculation of the health status; finally, errors and deviations are eliminated through the correction and statistical correction method of the health status, so the accuracy and reliability of this health status assessment are high.
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