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CN110568359B - Lithium battery residual life prediction method - Google Patents

Lithium battery residual life prediction method Download PDF

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CN110568359B
CN110568359B CN201910832555.5A CN201910832555A CN110568359B CN 110568359 B CN110568359 B CN 110568359B CN 201910832555 A CN201910832555 A CN 201910832555A CN 110568359 B CN110568359 B CN 110568359B
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lithium battery
remaining life
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陈泽华
乔建澍
刘忆恩
陈凯华
刘晓峰
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Taiyuan University of Technology
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    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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    • G01R31/36Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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    • G01R31/36Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
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Abstract

The invention discloses a method for predicting the residual service life of a lithium battery, which comprises the steps of firstly carrying out multi-scale decomposition on dischargeable capacity by using empirical mode decomposition, then respectively predicting decomposed information by using different methods, and finally adding results to obtain the dischargeable capacity of the lithium battery so as to obtain the residual service life of the lithium battery. The method and the device can effectively predict the charge state and the residual service life of the battery, have better prediction efficiency and prediction precision, effectively judge the future working capacity, find problems in time and avoid unnecessary troubles and loss.

Description

Lithium battery residual life prediction method
Technical Field
The invention relates to the field of lithium battery life prediction, in particular to a lithium battery residual life prediction method.
Background
The lithium battery is a novel energy source, replaces the traditional batteries such as lead storage batteries, nickel cadmium batteries and the like due to the advantages of high working voltage, large specific energy, high charging and discharging efficiency, low self-discharging rate, no memory effect, long cycle life and the like, and is applied to various fields such as mobile phones, computers, electric vehicles and the like. However, in the process of long-term use of the lithium battery, the discharge capacity of the lithium iron phosphate battery gradually decreases due to a series of physicochemical changes occurring inside the lithium battery, that is, the State of Health (State of charge) of the battery gradually decreases, and the related equipment may be damaged, and in a serious case, the whole system may be rushed, and even property loss and casualties may be caused. In recent years, relevant researchers have set themselves to develop better batteries on the one hand and have conducted a great deal of research into the prediction of battery life on the other hand. At present, the material and the manufacturing level of the battery are greatly improved, but the problem of the reduction of the state of charge is not fundamentally solved.
Disclosure of Invention
The invention aims to provide a method for predicting the residual life of a lithium battery.
The invention provides a lithium battery life prediction method, which comprises the following steps:
the method comprises the following steps: extracting lithium battery capacity data, current, voltage and temperature and corresponding time data in the lithium battery operation data to serve as lithium battery residual life prediction data, and dividing the lithium battery residual life prediction data into two groups, wherein one group is a training set, and the other group is a testing set;
step two: performing empirical mode decomposition on the residual life prediction data of the lithium battery, decomposing the residual life prediction data into a plurality of eigenmode functions as the characteristics of the residual life prediction data of the lithium battery under different scales; the features under different scales at least comprise information features of global attenuation tendency, capacity regeneration data and local fluctuation;
step three: setting parameters of the long and short term memory network model, and inputting the eigenmode function obtained by decomposition into the long and short term memory network model for training;
step four: setting parameters of the deep neural network, and inputting the residual quantity after extracting the eigenmode function, the current voltage temperature in the lithium battery operation data and the corresponding time data into a deep neural network model for training;
step five: and respectively inputting an eigenmode function obtained by performing empirical mode decomposition on the lithium battery residual life prediction data, the current voltage temperature in the lithium battery operation data and corresponding time data into the trained long-short term memory network model and the trained deep neural network model, and adding results output by the models to obtain a lithium battery residual life prediction result.
The method for carrying out empirical mode decomposition on the battery capacity data of the lithium battery comprises the following steps:
the first step is as follows: finding all extreme points of the sequence x (t);
the second step is that: forming a lower envelope x for the minimum points by interpolationl(t) forming an upper envelope x for the maximau(t);
The third step: calculating the average value of the envelope on the lower envelope:
m(t)=[xl(t)+xu(t)]/2 (1)
the fourth step: extracting an eigenmode function:
h(t)=x(t)-m(t) (2)
the fifth step: judging whether the termination condition is satisfied, if so, outputting x (t) and rn(t) ending the empirical mode decomposition, otherwise, executing the sixth step;
Figure BDA0002191186020000021
wherein N is original battery capacity data, and delta is a preset termination condition; j represents the iteration times, and if the iteration formula meets the formula (3), the calculation is ended;
and a sixth step: taking h (t) as one of the eigenmode functions:
cj(t)=h(t) (4)
the seventh step: return r (t) instead of x (t) to the first step for calculation:
r(t)=x(t)-cj(t) (5)
after the step of performing empirical mode decomposition on the battery capacity data of the lithium battery, the method further comprises the step of initializing deep neural network training parameters, and specifically comprises the following steps of:
after the step of performing empirical mode decomposition on the battery capacity data of the lithium battery, the method further comprises the step of initializing deep neural network training parameters, and specifically comprises the following steps:
according to the input variable, the connection weight omega between the input layer and the hidden layerijAnd the deviation b calculates the hidden layer output HjThe calculation formula is as follows:
Figure BDA0002191186020000031
f is a hidden layer excitation function, and the calculation formula is as follows:
y=x (7)
wherein l is the number of nodes of the hidden layer;
outputting H from a hidden layerjConnection weight omega between hidden layer and output layerjkAnd b, calculating the prediction output O of the deep neural network by the deviation b, wherein the calculation formula is as follows:
Figure BDA0002191186020000032
f is a hidden layer excitation function, and the calculation formula is as follows:
y=x (9)
wherein m is the number of nodes of the output layer.
Wherein, the parameters of the deep neural network are set as follows: the hidden layer is set to be 2 layers, the neuron number of each layer is set to be 32 and 8, the neuron number of the output layer is set to be 1, the activation function of the hidden layer neurons is set to be y-x, the activation function of the output layer is set to be y-x, the loss function is set to be mean square error (mse), and the optimizer uses adam; the number of training times varies from one starting point to another.
Wherein, the parameters of the long-term and short-term memory network model are set as follows: 2 batchs are taken for each training, the size of each batch is 32, the size of a hidden layer is 200, and the training times are set to be 400 times; and evaluating the long-short term memory network model, and predicting backwards on the basis of the evaluation data, wherein the quantity of the prediction data is different along with the difference of the prediction starting point.
The method comprises the following steps of inputting current, voltage and temperature in lithium battery residual life prediction data and corresponding time data into a trained deep neural network model, wherein the steps comprise:
selecting the number of layers of the hidden layer and the number of neurons of the hidden layer in the deep neural network algorithm; selecting two hidden layers according to the root mean square error and the result graph, wherein the number of the neurons of the hidden layers is 32 and 8 respectively;
and according to the selected extracted current, voltage, temperature and time characteristics, dividing the current, voltage and time characteristics into 5 groups of different training sets and test sets, and respectively training to obtain different neural network models.
The method comprises the following steps of inputting an eigenmode function obtained by empirical mode decomposition of lithium battery residual life prediction data into a trained long-short term memory network model, wherein the steps comprise:
selecting the hidden layer size and the time window of the long and short term memory model; selecting two layers of hidden layers according to the root mean square error and a result graph, wherein the size of the hidden layers is set to be 200, and the size of a time window is set to be 32;
the EMD-decomposed imfs information is predicted using the LSTM model, and the number of predicted points is different depending on the starting point.
When the training completion degree of the LSTM and DNN models is judged, Absolute Error (AE) and Root Mean Square Error (RMSE) are used as the standards of model performance.
Wherein, AE represents the difference between the actual residual life of the lithium battery and the predicted residual life of the lithium battery, and represents the accuracy of the predicted residual life of the lithium battery; RMSE represents the dischargeable capacity of the battery, indicating the accuracy of the state of charge prediction of the battery. Therefore, the accuracy of the model is evaluated by using the following equations 10 and 11:
(1)AE
AE=|T-P| (10)
wherein T represents true RUL and P represents predicted RUL;
(2)RMSE
Figure BDA0002191186020000041
n is the predicted node count, T, P represents the predicted state of charge value, s represents the point at which prediction begins, Ti+sRepresenting the actual state of charge, Pi+sRepresenting the predicted state of charge.
Different from the prior art, the method provided by the invention firstly carries out multi-scale decomposition on the dischargeable capacity by using empirical mode decomposition, then predicts the decomposed information by using different methods from transverse and longitudinal angles, and finally predicts the residual service life of the lithium battery. The method and the device can effectively predict the charge state of the battery, have better prediction efficiency and prediction precision, effectively judge the future working capacity, find problems in time and avoid unnecessary troubles and loss.
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Fig. 1 is a schematic flow chart of a lithium battery life prediction method provided by the present invention.
Fig. 2 is a diagram of dischargeable capacity of lithium battery No. 5 in the lithium battery life prediction method provided in the present invention.
Fig. 3 is a schematic diagram of information of each scale obtained by empirical mode decomposition of residual life prediction data of lithium battery No. 5 in the lithium battery life prediction method provided by the present invention.
Fig. 4-8 are diagrams illustrating a residual life prediction of lithium battery No. 5 in the method for predicting the life of a lithium battery according to the present invention.
Detailed Description
The technical solution of the present invention will be further described in more detail with reference to the following embodiments. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.
The invention provides a method for predicting the residual life of a lithium battery, which comprises the following steps:
the method comprises the following steps: extracting lithium battery capacity data, current, voltage and temperature and corresponding time data in the lithium battery operation data to serve as lithium battery residual life prediction data, and dividing the lithium battery residual life prediction data into two groups, wherein one group is a training set, and the other group is a testing set;
step two: performing empirical mode decomposition on the residual life prediction data of the lithium battery, decomposing the residual life prediction data into a plurality of eigenmode functions as the characteristics of the residual life prediction data of the lithium battery under different scales; the features under different scales at least comprise information features of global attenuation tendency, capacity regeneration data and local fluctuation;
step three: setting parameters of the long and short term memory network model, and inputting the eigenmode function obtained by decomposition into the long and short term memory network model for training;
step four: setting parameters of the deep neural network, and inputting the residual quantity after extracting the eigenmode function, the current voltage temperature in the lithium battery operation data and the corresponding time data into a deep neural network model for training;
step five: and respectively inputting an eigenmode function obtained by performing empirical mode decomposition on the lithium battery residual life prediction data, the current voltage temperature in the lithium battery operation data and corresponding time data into the trained long-short term memory network model and the trained deep neural network model, and adding results output by the models to obtain a lithium battery residual life prediction result.
The method for carrying out empirical mode decomposition on the battery capacity data of the lithium battery comprises the following steps:
the first step is as follows: finding all extreme points of the sequence x (t);
the second step is that: forming a lower envelope x for the minimum points by interpolationl(t) forming an upper envelope x for the maximau(t);
The third step: calculating the average value of the envelope on the lower envelope:
m(t)=[xl(t)+xu(t)]/2 (1)
the fourth step: extracting an eigenmode function:
h(t)=x(t)-m(t) (2)
the fifth step: judging whether the termination condition is satisfied, if so, outputting x (t) and rn(t) ending the empirical mode decomposition, otherwise, executing the sixth step;
Figure BDA0002191186020000061
wherein N is original battery capacity data, and delta is a preset termination condition; j represents the iteration times, and if the iteration formula meets the formula (3), the calculation is ended;
and a sixth step: taking h (t) as one of the eigenmode functions:
cj(t)=h(t) (4)
the seventh step: return r (t) instead of x (t) to the first step for calculation:
r(t)=x(t)-cj(t) (5)
after the step of performing empirical mode decomposition on the battery capacity data of the lithium battery, the method further comprises the step of initializing deep neural network training parameters, and specifically comprises the following steps of:
after the step of performing empirical mode decomposition on the battery capacity data of the lithium battery, the method further comprises the step of initializing deep neural network training parameters, and specifically comprises the following steps:
according to the input variable, the connection weight omega between the input layer and the hidden layerijAnd the deviation b calculates the hidden layer output HjThe calculation formula is as follows:
Figure BDA0002191186020000071
f is a hidden layer excitation function, and the calculation formula is as follows:
y=x (7)
wherein l is the number of nodes of the hidden layer;
outputting H from a hidden layerjConnection weight omega between hidden layer and output layerjkAnd b, calculating the prediction output O of the deep neural network by the deviation b, wherein the calculation formula is as follows:
Figure BDA0002191186020000072
f is a hidden layer excitation function, and the calculation formula is as follows:
y=x (9)
wherein m is the number of nodes of the output layer.
The parameters of the deep neural network are set as follows: the hidden layer is set to be 2 layers, the neuron number of each layer is set to be 32 and 8, the neuron number of the output layer is set to be 1, the activation function of the hidden layer neurons is set to be y-x, the activation function of the output layer is set to be y-x, the loss function is set to be mean square error (mse), and the optimizer uses adam to initialize the deep neural network.
The parameters of the long-short term memory model are set as follows: 2 batchs are taken for each training, the size of each batch is 32, the size of the hidden layer is 200, and the training times are set to be 400 times. The model is then evaluated and predicted backwards on the basis of the evaluation data, the amount of prediction data varying from one prediction starting point to another.
Selecting the number of layers of the hidden layer and the number of neurons of the hidden layer in the deep neural network algorithm; selecting two layers of hidden layers according to the root mean square error and the result graph, wherein the number of the neurons of the hidden layers is 32 and 8 respectively;
according to the characteristics of the selected extracted current, voltage, temperature, time and the like, the neural network model is divided into 15 groups of different training sets and test sets, and different neural network models are obtained through training respectively.
Selecting the size of a hidden layer and a time window of the long-term and short-term memory model; selecting two layers of hidden layers according to the root mean square error and a result graph, wherein the size of the hidden layers is set to be 200, and the size of a time window is set to be 32;
the EMD-decomposed imfs information is predicted using the LSTM model, and the number of predicted points is different depending on the starting point.
And predicting by using the obtained EMD-LSTM-DNN model to obtain a predicted mean square error, and verifying effectiveness and accuracy.
We used Absolute Error (AE), and Root Mean Square Error (RMSE) as criteria for model performance.
AE represents the difference between the actual RUL and the predicted RUL, indicating the accuracy of the predicted RUL. RMSE represents the dischargeable capacity of the battery, indicating the accuracy of the state of charge prediction of the battery. Equation 10 and equation 10 are used to evaluate the accuracy of the model:
(3)AE
AE=|T-P| (10)
where T represents the true RUL and P represents the predicted RUL.
(4)RMSE
Figure BDA0002191186020000081
n is the predicted number of nodes, T, P represents the predicted state of charge value, s represents the point at which prediction beginsi+sRepresenting the actual state of charge, Pi+sRepresenting the predicted state of charge.
The experimental data used in this example was from battery number five in the NASA experimental data set. The relevant rated data of the lithium battery of the experimental model are as follows: rated capacity 2Ah, rated charge cut-off voltage 4.2V, and rated discharge cut-off voltage 2.7V. The input parameter is information of each scale of battery capacity after empirical mode decomposition, and the output parameter is available capacity of the battery pack.
After empirical mode decomposition, the dischargeable capacity and the remaining service life of the battery are predicted at 5 different starting points, and the comparison result of the model on the predicted situation and the actual situation of a test set is as follows:
fig. 2 is a graph of the dischargeable capacity of battery No. 5, and it can be seen that the capacity data shows a downward trend as the number of cycles increases but the intermediate process slightly increases. Fig. 3 is an exploded view of empirical mode, which is used to decompose the volume data into 3 pieces of information and a margin, fig. 4-8 are a comparison graph of prediction and reality using empirical mode and deep neural network algorithm and long-short term memory model, blue is used to indicate the prediction result, and yellow is used to indicate the actual volume. It can be found that the algorithm can effectively fit the trend of the dischargeable capacity of the lithium battery.
Through research, the number of training samples, the number of layers of hidden layers and the number of nodes of neurons of hidden layers have great influence on the performance of the trained deep neural network prediction model. Generally, input variables are well selected in advance by researchers according to professional knowledge and rich experience, but in practical application, the selection of the input variables is difficult to determine in advance, the prediction performance of the model is reduced, and therefore, the optimization of the input independent variable parameters in the process of training the prediction model has important significance.
The empirical mode decomposition algorithm can effectively decompose the capacity data into information with physical significance in a plurality of scales. After decomposition, the prediction was performed by different methods at 5 different starting electricity, and the average root mean square error of the prediction was 0.00096, which demonstrates the effectiveness of the method proposed herein.
Table 1 shows the absolute error and the root mean square error obtained by 5 different starting nodes in the method for predicting the service life of the lithium battery of the No. 5 battery provided by the present invention.
Figure BDA0002191186020000091
Figure BDA0002191186020000101
TABLE 15 result chart of battery prediction
Aiming at the problem of service life prediction of the lithium battery, the invention firstly carries out multi-scale decomposition on the capacity data based on an empirical mode decomposition algorithm, and multi-scale information obtained after decomposition is predicted by different methods, so that the lithium battery has excellent performance.
Different from the prior art, the method provided by the invention firstly carries out multi-scale decomposition on the dischargeable capacity by using empirical mode decomposition, then predicts the decomposed information by using different methods from transverse and longitudinal angles, and finally predicts the residual service life of the lithium battery. The method and the device can effectively predict the charge state of the battery, have better prediction efficiency and prediction precision, effectively judge the future working capacity, find problems in time and avoid unnecessary troubles and loss.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (9)

1.一种锂电池剩余寿命预测方法,其特征在于,包括:1. A method for predicting the remaining life of a lithium battery, comprising: 步骤一:提取锂电池运行数据中的锂电池容量数据、电流电压温度以及对应的时间数据,作为锂电池剩余寿命预测数据,将锂电池剩余寿命预测数据分成两组,一组为训练集,另一组为测试集;Step 1: Extract the lithium battery capacity data, current, voltage, temperature, and corresponding time data in the lithium battery operation data, as the remaining life prediction data of the lithium battery, and divide the remaining life prediction data of the lithium battery into two groups, one is the training set, the other One set is the test set; 步骤二:对锂电池剩余寿命预测数据进行经验模态分解,分解为多个本征模函数,作为锂电池剩余寿命预测数据在不同尺度下的特征;其中,不同尺度下的特征至少包括全局衰减趋势、容量再生数据及局部波动的信息特征;Step 2: Perform empirical modal decomposition on the remaining life prediction data of the lithium battery, and decompose it into multiple eigenmode functions, which are used as the characteristics of the lithium battery remaining life prediction data at different scales; wherein, the characteristics at different scales include at least global attenuation Information characteristics of trends, capacity regeneration data and local fluctuations; 步骤三:对长短期记忆网络模型的参数进行设置,将分解得到的本征模函数,输入长短期记忆网络模型进行训练;Step 3: Set the parameters of the long-term and short-term memory network model, and input the eigenmode function obtained by decomposition into the long-term and short-term memory network model for training; 步骤四:对深度神经网络的参数进行设置,使用提取本征模函数后的余量,输入深度神经网络模型进行训练;Step 4: Set the parameters of the deep neural network, use the margin after extracting the eigenmode function, and input the deep neural network model for training; 步骤五:将锂电池剩余寿命预测数据进行经验模态分解得到的本征模函数输入长短期记忆网络模型,将锂 电池运行数据中的电流电压温度以及对应的时间数据输入深度神经网络模型,将模型输出的结果相加作为锂电池剩余寿命预测结果。Step 5: Input the eigenmode function obtained by the empirical modal decomposition of the remaining life prediction data of the lithium battery into the long short-term memory network model, input the current, voltage, temperature and corresponding time data in the lithium battery operating data into the deep neural network model, and input the The results of the model output are added as the prediction result of the remaining life of the lithium battery. 2.根据权利要求1所述的锂电池剩余寿命预测方法,其特征在于:2. The method for predicting the remaining life of a lithium battery according to claim 1, wherein: 对锂电池的电池容量数据进行经验模态分解的步骤包括:The steps of empirical modal decomposition of battery capacity data for lithium batteries include: 第一步:以锂电池剩余寿命预测数据构建序列x(t),找出序列x(t)的所有极值点;The first step: construct a sequence x(t) with the remaining life prediction data of lithium batteries, and find all the extreme points of the sequence x(t); 第二步:用插值法对极小值点形成下包络xl(t),对极大值形成上包络xu(t);The second step: use the interpolation method to form the lower envelope x l (t) for the minimum value point, and form the upper envelope x u (t) for the maximum value; 第三步:计算下包络上包络的平均值:Step 3: Calculate the average of the upper envelope of the lower envelope: m(t)=[xl(t)+xu(t)]/2 (1)m(t)=[x l (t)+x u (t)]/2 (1) 第四步:提取本征模函数:Step 4: Extract the eigenmode function: h(t)=x(t)-m(t) (2)h(t)=x(t)-m(t) (2) 第五步:判断公式3是否满足,如果满足输出x(t)和余量rn(t)结束经验模态分解,否则,执行第六步;The fifth step: judge whether formula 3 is satisfied, if the output x(t) and the margin r n (t) are satisfied, the empirical mode decomposition is ended, otherwise, the sixth step is performed;
Figure FDA0003153131370000021
Figure FDA0003153131370000021
其中N为循环次数,δ为预设的阈值;j表示迭代次数;where N is the number of cycles, δ is a preset threshold; j is the number of iterations; 第六步:将h(t)作为本征模函数的其中之一:Step 6: Use h(t) as one of the eigenmode functions: cj(t)=h(t) (4)c j (t)=h(t) (4) 第七步:将r(t)代替x(t)回到第一步进行计算:Step 7: Replace r(t) with x(t) and go back to the first step for calculation: r(t)=x(t)-cj(t) (5)。r(t)=x(t) -cj (t) (5).
3.根据权利要求1所述的锂电池剩余寿命预测方法,其特征在于:3. The method for predicting the remaining life of a lithium battery according to claim 1, wherein: 对锂电池剩余寿命预测数据进行经验模态分解的步骤之后,还包括初始化深度神经网络训练参数的步骤,具体包括:After the step of performing empirical modal decomposition on the remaining life prediction data of the lithium battery, it also includes the step of initializing the training parameters of the deep neural network, which specifically includes: 根据输入变量、输入层和隐含层间的连接权值ωij以及偏差b计算隐含层输出Hj,计算公式为:The hidden layer output H j is calculated according to the input variable, the connection weight ω ij between the input layer and the hidden layer, and the deviation b. The calculation formula is:
Figure FDA0003153131370000022
Figure FDA0003153131370000022
f为隐含层激励函数,计算公式为:f is the activation function of the hidden layer, and the calculation formula is: y=x (7)y=x (7) 式中l为隐含层的节点数;where l is the number of nodes in the hidden layer; 根据隐含层输出Hj、隐含层和输出层间的连接权值ωjk以及偏差b计算深度神经网络的预测输出Ok,计算公式为:The predicted output O k of the deep neural network is calculated according to the output H j of the hidden layer, the connection weight ω jk between the hidden layer and the output layer, and the deviation b. The calculation formula is:
Figure FDA0003153131370000023
Figure FDA0003153131370000023
f为隐含层激励函数,计算公式为:f is the activation function of the hidden layer, and the calculation formula is: y=x (9)y=x (9) 式中m为输出层的节点数。where m is the number of nodes in the output layer.
4.根据权利要求1所述的锂电池剩余寿命预测方法,其特征在于:4. The method for predicting the remaining life of a lithium battery according to claim 1, wherein: 深度神经网络的参数设置为:隐含层设为2层,各层神经元个数设为32、8,输出层的神经元个数设为1,隐含层神经元的激活函数设为y=x,输出层的激活函数设为y=x,损失函数设为均方误差(mse),优化器使用adam;训练次数根据开始点的不同而不同。The parameters of the deep neural network are set as follows: the hidden layer is set to 2 layers, the number of neurons in each layer is set to 32 and 8, the number of neurons of the output layer is set to 1, and the activation function of the neurons of the hidden layer is set to y =x, the activation function of the output layer is set to y=x, the loss function is set to the mean squared error (mse), and the optimizer uses adam; the number of training times varies according to the starting point. 5.根据权利要求1所述的锂电池剩余寿命预测方法,其特征在于:5. The method for predicting the remaining life of a lithium battery according to claim 1, wherein: 长短期记忆网络模型的参数设置为:每次训练取2个batch,每个batch的大小为32,隐层大小为200,训练次数设置为400次;对长短期记忆网络模型进行评估在评估数据的基础上,向后预测,预测数据的数量随着预测开始点的不同而不同。The parameters of the long and short-term memory network model are set as follows: 2 batches are taken for each training, the size of each batch is 32, the size of the hidden layer is 200, and the number of training times is set to 400 times; the long-term and short-term memory network model is evaluated in the evaluation data. On the basis of backward forecasting, the amount of forecast data varies with the starting point of the forecast. 6.根据权利要求1所述的锂电池剩余寿命预测方法,其特征在于:6. The method for predicting the remaining life of a lithium battery according to claim 1, wherein: 锂电池剩余寿命预测数据中的电流电压温度以及对应的时间数据输入训练好的深度神经网络模型,步骤包括:The current, voltage, temperature and corresponding time data in the lithium battery remaining life prediction data are input into the trained deep neural network model, and the steps include: 进行深度神经网络算法隐含层的层数和隐含层神经元的个数的选择;其中,根据均方根误差与结果图,选取两层隐含层,隐含层的神经元的个数分别32、8;Carry out the selection of the number of hidden layers and the number of neurons in the hidden layer of the deep neural network algorithm; among them, according to the root mean square error and the result graph, select two hidden layers and the number of neurons in the hidden layer 32, 8 respectively; 根据选定所提取出来的电流电压温度时间特征,分成5组不同的训练集和测试集,分别进行训练得到不同的神经网络模型。According to the selected extracted current, voltage, temperature and time characteristics, it is divided into 5 different training sets and test sets, and different neural network models are obtained by training respectively. 7.根据权利要求1所述的锂电池剩余寿命预测方法,其特征在于:7. The method for predicting the remaining life of a lithium battery according to claim 1, wherein: 锂电池剩余寿命预测数据进行经验模态分解得到的本征模函数输入训练好的长短期记忆网络模型,步骤包括:The eigenmode function obtained by the empirical mode decomposition of the remaining life prediction data of the lithium battery is input into the trained long-term and short-term memory network model, and the steps include: 进行长短期记忆模型的隐层大小和时间窗的选择;其中,根据均方根误差与结果图,选取两次层隐含层,隐层大小设置为200,时间窗大小设置为32;Select the hidden layer size and time window of the long short-term memory model; among them, according to the root mean square error and the result graph, select two hidden layers, the hidden layer size is set to 200, and the time window size is set to 32; 将EMD分解后的imfs信息,使用LSTM模型分别预测,根据开始点的不同,预测的点的个数也不同。The imfs information decomposed by EMD is predicted separately using the LSTM model. According to the different starting points, the number of predicted points is also different. 8.根据权利要求1所述的锂电池剩余寿命预测方法,其特征在于:8. The method for predicting the remaining life of a lithium battery according to claim 1, wherein: 判断LSTM和DNN模型的训练完成度时,采用绝对误差(AE),和均方根误差(RMSE)作为模型性能的标准。When judging the training completion of LSTM and DNN models, absolute error (AE) and root mean square error (RMSE) are used as the standard of model performance. 9.根据权利要求8所述的锂电池剩余寿命预测方法,其特征在于:9. The method for predicting the remaining life of a lithium battery according to claim 8, wherein: AE表示实际锂电池剩余寿命与预测锂电池剩余寿命之间的差值,表示预测锂电池剩余寿命的准确性;RMSE表示电池的可放电容量,表示电池的荷电状态预测的准确性;所以采用公式10和公式11来评判模型的准确性:AE represents the difference between the actual remaining life of the lithium battery and the predicted remaining life of the lithium battery, indicating the accuracy of predicting the remaining life of the lithium battery; RMSE represents the dischargeable capacity of the battery, indicating the accuracy of the battery state of charge prediction; so use Equation 10 and Equation 11 to judge the accuracy of the model: (1)AE(1) AE AE=|T-P| (10)AE=|T-P| (10) 其中T代表真实的RUL,P代表预测的RUL;where T represents the real RUL and P represents the predicted RUL; (2)RMSE(2)RMSE
Figure FDA0003153131370000041
Figure FDA0003153131370000041
n是预测的节点个数,s表示预测开始的点,Ti+s代表真实的电池荷电状态,Pi+s代表预测电池的荷电状态。n is the number of predicted nodes, s represents the point at which the prediction starts, T i+s represents the actual state of charge of the battery, and P i+s represents the state of charge of the predicted battery.
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