Study On High Temperature Fault Diagnosis Method Of Vehicle Lithium-Ion Battery Based On EKF

With the global energy shortage and environmental degradation,the demand for research and development of electric vehicles is increasingly urgent in various countries.With the development and popularization of electric vehicles,the spontaneous combustion of electric vehicles has become increasingly frequent.One of the important components of electric vehicles is the high-temperature failure of lithium-ion batteries,which is the main cause of spontaneous combustion.It is of great significance to diagnose the high-temperature failure of lithium-ion batteries in time.The research object of this article is the ternary lithium-ion battery,focusing on the high-temperature fault diagnosis method of lithium-ion battery.The next content is the main research work:Above all,the working principle and characteristics of the lithium-ion battery are introduced.Based on the Thevenin battery model,considering the temperature factor,a first-order equivalent circuit model of the battery is established,and the mathematical expressions of the model parameters are obtained.The hybrid impulse characteristic experiment is designed,and the battery model parameters are fitted by offline identification method at SOC points at equal intervals,and the parameter identification table and fitting curve of the lithium-ion battery equivalent circuit model are obtained.According to the principle of extended Kalman filter(EKF),the lithium-ion battery equivalent circuit model is designed to diagnose the high-temperature battery fault diagnosis algorithm,and the state equation and observation equation of the diagnosis algorithm,the calculation process,and the battery terminal voltage residual error calculation are obtained.Formula and coded in Matlab software.According to the principle of Gaussian distribution,the probability distribution density relationship between the false detection rate PFA and the state parameter fault threshold ? is obtained,and the corresponding mathematical relationship is derived.The fault threshold is determined by the false detection rate.In order to verify the effectiveness of the fault diagnosis algorithm,a battery bench test-was designed,the experimental scheme and the structure of the experimental platform were introduced,and a battery management system(BMS)for the bench test was designed.Experiments prove that the fault diagnosis algorithm responds well to high-temperature faults in lithium-ion batteries when the ambient temperature changes,and has good predictability for battery terminal voltage residuals.The EKF-based lithium ions studied in this paper The high-temperature battery fault diagnosis algorithm has certain reference value for the diagnosis of lithium-ion battery high-temperature faults.