Research On Lithium Battery Health Management Based On Circuit Fault Diagnosis Method

With the rapid development of consumer electronics,electric vehicles and other industries,the market demand for lithium batteries continues to grow.However,the frequent accidents caused by the safety problems of lithium battery bring great losses to people.Therefore,scientific and effective evaluation and management of the state of health(SOH)of lithium batteries will greatly improve the safety of lithium batteries.At the same time,the evaluation and management of SOH have important guiding significance for the use,maintenance and economic analysis of lithium battery.At present,domestic and foreign scholars mainly obtain lithium battery SOH by establishing a lithium battery evaluation model.The research on lithium battery SOH has achieved certain research results,but because the lithium battery is in working state,the internal electrochemical reaction is very complicated.Therefore,there are still some deficiencies in the practical application of the evaluation and management of lithium battery SOH.With the aging of lithium battery,the accuracy of prediction of SOH of lithium battery gradually decreases,which brings a lot of inconvenience to the use and maintenance of lithium battery.In this paper,a new idea of research on lithium battery SOH is proposed,and the method of analog circuit fault diagnosis is introduced into the research field of lithium battery SOH.Firstly,it analyzes the research status of lithium battery SOH at home and abroad,and then summarizes various analysis methods and future development trends of lithium battery SOH research at home and abroad.An experimental measurement platform was built to identify the parameters of the equivalent circuit model of lithium batteries.The lithium battery internal resistance measurement system was researched and designed by using AC injection method combined with Kelvin four-wire detection method,AC-DC separation technology and weak signal detection technology,etc.The system can accurately measure the internal resistance,voltage and other parameters of the lithium battery,and the measurement speed is fast.The measurement data can be saved in real time.Using the experimental measurement platform,the parameters of the lithium battery equivalent circuit model were identified.The pulse discharge method and the polynomial fitting method are used to complete the identification of the open circuit voltage;the AC impedance method is used to complete the identification of the ohm internal resistance;the pulse discharge method and the exponential fitting method are used to complete the identification of the polarization capacitance and polarization internal resistance.The circuit simulation software is used to simulate the failure of the equivalent circuit of the lithium battery,the output response is obtained by applying an excitation signal to the equivalent circuit,and then the wavelet transform is used to extract the feature of the output response signal of the equivalent circuit,and then input the extracted feature data to the BP(Back Propagation,BP)neural network fused with the Cuckoo Search(CS)algorithm for training and testing,and obtain the diagnosis result of the equivalent circuit of the lithium battery,then analyze the SOH of the lithium battery according to the diagnosis result,and analyze and locate the failure part of the lithium battery through the failure component in the equivalent circuit,simulation results show that good diagnostic results have been achieved.This work is a useful exploration of the use of circuit fault diagnosis methods to analyze the health status of lithium batteries,to a certain extent,it has enriched the research results of evaluating and managing the health status of lithium batteries.