Estimation Of Charging State Of Lithium Batteries For Electric Vehicles

With the rapid development of technology and economy,the problem of energy shortage and environmental pollution is extremely urgent.Therefore,people will pay more attention to the new energy technology industry.The prevalence of electric vehicles is one of them.As one of the core components of electric vehicle energy supply,lithium battery failure will reduce the reliability of the whole system.Therefore,it is particularly important to equip lithium battery with efficient and intelligent battery management system.As an important part of the battery management system,lithium battery SOC estimation can not only estimate the real-time status of lithium batteries,but also optimize the battery management system.Therefore,this paper takes lithium batteries as the research object,and studies the core subject of SOC estimation of lithium batteries.This paper describes the basic characteristics of lithium battery and the influencing factors of the equivalent circuit model of lithium battery.Several equivalent circuit models of lithium battery are analyzed.In view of the difficulties in estimating SOC of lithium batteries and the low accuracy of estimating SOC of lithium batteries in the second-order RC equivalent circuit model,the second-order RC model is improved by applying the circuit equivalent principle.Firstly,based on the improved equivalent circuit model of lithium battery,the recursive least squares algorithm with limited memory and Kalman filter algorithm are used to identify the unknown parameters in the model.By comparing and analyzing the simulation results of these two parameter identification methods,The recursive least squares algorithm that defines the defined memory has better recognition performance.Then based on this,combined with the unscented Kalman filter algorithm to achieve the estimation of lithium battery SOC.Finally,based on the MATLAB/Simulink simulation platform,the proposed method is verified by experiments.The experimental results show that the simplified equivalent circuit model of lithium battery is feasible and effective,which can accurately estimate the SOC of battery.Figure [45] table [5] reference [79].