An Electric Vehicle Lithium-ion Battery Optimized Charging Strategy Research

The lithium-ion battery optimized charging strategy is one of the core functions of the battery management system.Nowadays,the charging process has always hindered the development of electric vehicles.The charging process of an electric vehicles is much longer than that of a conventional internal combustion car.In addition,the charging time is shortened by charging in high-rate current,but the temperature of the battery is sharply increased,which undoubtedly makes the electric vehicle unsafe.Due to the sensitivity to temperature,the charging performance of lithium-ion batteries is quite different at different temperatures.Therefore,an excellent charging strategy is indispensable for the development of electric vehicles.In this paper,based on different ambient temperatures,charging time and charging temperature rise are taken as optimization targets,and the optimization strategy of lithium-ion battery charging strategy is carried out.Firstly,the model of the lithium-ion battery and the temperature model are established,as well as the selection of the battery model and the identification of the offline parameters.After the comprehensive evaluation of the model accuracy and computational complexity,the appropriate power battery model is selected.Aiming at the problem of optimized charging strategy for lithium ion power,an optimized charging strategy based on battery model for multiorder constant heat production rate is proposed.In order to reduce the charging time and temperature rise,this paper analyzes the SOC region of battery charging,the order of charging curve and the weight between charging time and charging temperature rise.Aiming at the problem of optimal charging of batteries in a wide temperature range,a temperature-based multi-order constant heating optimization charging strategy is proposed.This is a charging strategy based on the dynamic characteristics of the battery at different temperatures,using different charging curves in different temperature ranges.The effects of using the same charging curve at different temperatures were analyzed.Finally,the optimized charging curve MAP diagrams at different temperatures are generated and embedded in the battery management system,thus reducing the computational complexity of the battery management system.In order to verify the feasibility of the proposed method,a comparative experiment was used to verify the optimal charging strategy of power batteries.To solve the problem of optimal charging of power battery,this paper proposes a temperature-based multi-step constant heating optimization charging method.The power battery optimized charging strategy and the traditional charging method were compared experimentally at different ambient temperatures.The experimental results show that the proposed method can improve the charging temperature rise and charging time at different temperatures compared with the traditional constant current and constant voltage charging method.