Study On SOC Estimation Method Of Lithium Ion Battery Based On EKF

With the available resources decreasing constantly and the environmental pollution aggravating increasingly,the new energy electric vehicle has been gradually become the burgeoning green product,which is pursued by countries.The aspects of power battery and the battery management system are the key technology of electric vehicle,and estimating the state of charge(SOC)of power battery accurately has an important meaning of the electric vehicle' performance.This study chooses the lithium iron phosphate battery as the research object,and then does research on the estimation methods of lithium battery SOC.This study has fully investigated the research statuses and characteristics on estimation methods of battery SOC at home and abroad,preliminarily selected and set up the thevenin equivalent circuit model,and designed a simulation model which is based on extended kalman filter(EKF)algorithm for estimating SOC.Then,by means of the SOC's simulation proof under different discharge conditions,this estimation method and model are proved to be feasible.In order to improve the estimation accuracy of battery SOC,this study on the basis of the existence of the model error,has dynamically corrected some relevant parameters,and has improved the existing estimation algorithm.At last,according to the contrastive analysis of the results of simulation conditions verification,the results show that the improved EKF estimation algorithm has better adaptability and stronger convergence ability,can achieve higher estimation accuracy of SOC,and the accuracy can be controlled in the range of the error of the 1.5%.