Variable Order Modeling and Parameter Identification based on Lithium iron Phosphate Battery

In this paper, aiming at the low approximation degree of low-order model and the complex structure of high-order model existing in the current equivalent circuit model of lithium-ion battery for vehicles, a variable order equivalent circuit model of power battery was established based on the RC model to solve the contradiction between the accuracy and practicability of the battery model. Firstly, the characteristics of lithium iron phosphate batteries commonly used in electric vehicles were analyzed. The resistance and capacity identification was carried out according to the model characteristics. The order identification was carried out using Akaike Information Criterion (AIC). The final simulation results show that the accuracy error of the model is stable within 12mV, and the error stability is high, demonstrating the superiority of the model.