Fault Monitoring And Diagnosis Of Electric Vehicle Power Battery

In recent years,the electric vehicle industry has developed rapidly due to the strong support of the country and the increase of people's awareness of environmental protection.As the power source of electric vehicles,power batteries are the key to improving the performance of electric vehicles,and their safety issues have been widely concerned.On the one hand,there are inconsistencies among the single cells in the battery pack system,and the difference between the batteries in the operation process is getting bigger and bigger,which eventually leads to the degradation of the battery system performance.On the other hand,the complex use environment may cause internal short circuit of the single battery during using,and the large amount of heat generated will cause thermal runaway of the battery and cause safety accidents such as fire and explosion.In view of the above problems,for the electric vehicle battery system,the fault diagnosis algorithm is researched on the single and overall aspect,the fault diagnosis strategy is formulated,and the battery monitoring and diagnosis system is designed.First of all,lithium-ion batteries are used as the research object to explore the failure mechanism of the short circuit in the battery itself.The results show that the internal short circuit of the battery will cause abnormal changes in temperature and voltage.Secondly,for the abnormal temperature change when the cell has an internal short circuit fault,a fault diagnosis method based on the internal temperature is proposed.By analyzing the current relatively common battery models,a simple thermoelectric coupling model is established to estimate the internal temperature of the battery,and the feasibility of the model is verified through simulation experiments.Meanwhile,a fault diagnosis method based on the ARX model is proposed for the abnormal voltage change when the cell has an internal short circuit fault.Through the establishment of a fault simulation model,the ARX model is combined with the moving window deviation algorithm to monitor abnormal changes of model parameters.The simulation results show that the algorithm can successfully identify the short circuit fault in the batteryFinally,for the fault of the battery pack,the threshold method is used for fault diagnosis,and combined with the above-mentioned fault diagnosis method for the cell,a battery monitoring and diagnosis system is designed based on the Matlab/Simulink platform.In addition,HIL testing is carried out,and the feasibility of the system is verified by adopting the method of fault injection.