State-of-charge Estimation Of Lithium-ion Power Battery Considering Temperature Influence

In recent years,with the increasing intensification of global environmental pollution and the depletion of fossil fuel resources,the vigorous development of clean energy has become a necessary trend for future development.As a typical representative of clean and environmental protection,electric vehicles have always been favored by the world with low emissions and low consumption.Lithium batteries,as the main source of power for electric vehicles,have become research hotspots in recent years.The state of charge(SOC)of the power battery directly reflects the remaining capacity of the battery and is one of the important parameters of the electric vehicle,which directly affects the safety control of the electric vehicle and the evaluation of the sustainable mileage.Therefore,the accurate estimation of SOC is of great significance to the effective management of battery power and accurate estimation of cruising range,and to avoid battery overcharge and over discharge.This article first introduces the structural principles and operating characteristics of lithium batteries,highlights the advantages of lithium titanate batteries in applications,and provides reliable experimental objects for subsequent simulations.Then introduces the main SOC estimation algorithm at this stage,and determines the algorithm used in the subsequent estimation of SOC through analysis and comparison.Aiming at the battery model,establishing an accurate power battery model is of great help to the research of the battery system.The accurate battery model lays the foundation for the battery management system(BMS)to achieve precise control.To this end,this article introduces commonly used lithium battery models,and on this basis,select the combination model of the electrochemical model.This model solves the problems of complex model and many parameters.However,the design did not consider the influence of temperature on the specific model parameters,so this paper considers temperature compensation on the basis of the model to improve the accuracy of the lithium battery electrochemical model.For the battery SOC estimation algorithm,the article first introduces the principles and methods of commonly used algorithms.On the basis of the established battery model,combined with the Extended Kalman Filter(Extended Kalman Filter,EKF)algorithm,the dynamic estimation of the SOC of the lithium battery is realized.Simulate the actual working conditions of electric vehicles under different ambienttemperatures to conduct a discharge test of lithium batteries,and compare the accuracy of the SOC algorithm without temperature compensation and the compensated SOC algorithm.The research results show that the proposed method is suitable for lithium batteries at different temperatures and can achieve a more accurate estimation.In this paper,Guo Xuan IFR32132 cylindrical lithium iron phosphate power battery is selected as the research object,with constant temperature and humidity.According to the experimental data,the temperature compensation model is established,which is used in SOC estimation of battery.The verification experiment shows that the temperature compensation model has an obvious positive effect on improving the accuracy of SOC estimation,and achieves the expected purpose.