State Of Charge Estimation And Charging And Discharging Strategy Research Of Power Battery Pack On Electric Vehicle

With the rapid development of new energy vehicles,as an important component of electric vehicle battery management system has been a research focus.In battery management system,SOC,SOP and other state estimation algorithm is the core technology,Accurate state estimation is the key to efficient safely charge and discharge of the power battery.In this thesis,as lithium battery being for research object,about SOC estimation and charge-discharge strategy,study works are carried out as follows:The working characteristic of the lithium battery are analyzed.The curves of the battery characteristic parameters are obtained by experiments designed.After the analysis and the summary of commonly used battery model,the second-order equivalent circuit model is determined as the important basis for estimating the battery status,and the state equations of second order equivalent circuit model are derived.The characteristics of national and international SOC estimation algorithm are analyzed and summarized,that the real-time on-line closed-loop correction is a key to precision and robustness of the algorithm is pointed out.Considering the conditions of the embedded system with limited resources at the same time,the SOC estimation algorithm of PID as the feedback correction link is designed.On the basis of second-order equivalent circuit model,SOP estimation is studied as the main basis of charge and discharge strategy of battery pack.The characteristics of the existing methods for estimating the battery SOP are analyzed,based on the second-order design equivalent circuit model,the SOP estimation method under the limits of battery current,voltage,SOC is designed to provide real-time battery system peak power data as reference for vehicle.In addition,to reduce the inconsistency of the battery,onboard passive balance is designed to guarantee battery system s effective charging and discharging.Finally,Battery pack state estimation simulation model is built in SIMULINK,combining with the vehicle simulation software ADVISOR,the effectiveness of the SOC,SOP state estimation algorithm are verified by simulation experiment.The research work of this thesis has engineering application value to state estimation of battery pack.