Research On State Of Charge Estmation Method For LEP Batteries Based On Modified Electrochemical Model

As a kind of power battery,LFP battery is widely used for its high discharge rate and well safety performance.Especially in recent years,the rapid development of electric vehicles(EVs),many electric bus and some EVs have been put into use.Battery Management System(BMS)is the core System for the detection and control of Battery work.Among them,the State of Charge(SOC)of the Battery is the core part of the BMS.The accuracy of SOC is directly related to the working State,battery life,safety performance and other indicators of the Battery.At present,the widely-used SOC estimation algorithm is model-based SOC estimation algorithm,and a high C-rate model is the basis for accurate calculation of SOC.However,the error increases with the increase of C-rate in the battery model,and there is no battery model that can maintain high precision stably under high C-rates.In this paper,based on the Improved Single Particle Model(SP+),an electrochemical modified Model based on the C-rate is obtained under the condition of 4C.Based on the modified model,an algorithm suitable for the model is determined and implemented on the engineering platform.The detailed work of this project is as follows:Firstly,based on the SP+ model,this paper extended the structure of the SP+ model by analyzing the parameter reduction process of SP+ model and the influence of C-rates on the model due to the increasing error of battery models by high C-rates at present.Under the condition of structural modification,sensitivity analysis of parameters of SP+ model was carried out by analyzing the meaning of parameters of SP+ model to investigate the influence of current multiplier on battery parameters.and an electrochemical modified model based on C-rates was established.Secondly,due to the condition that many kind of algorithms all can suit with the model,this paper designs the mainstream model-based algorithm,and embedded the modified model.By comparing the accuracy and computational efficiency of SOC estimation under different algorithms,a SOC estimation algorithm that is most suitable for this model is selected.Finally,in order to simulate the operation of the SOC estimation system under actual conditions,the SOC estimation engineering realization and experimental verification based on the modified model and UKF algorithm were carried out in this paper.Based on Simulink platform,the SOC estimation algorithm system was reestablished.The established model was converted into embedded C code and imported into the embedded platform through Simulink code conversion technology.The SOC estimation experiment was conducted to test the SOC estimation accuracy of the algorithm under the embedded platform under different multiples.