Research On Li-ion Battery Energy Management System Of Electric Vehicle

Under the rapid development of global industrial and economy,the development of the vehicle industry has made great progress.Recent years,the air pollution is more and more intense.In this context,the development of electric vehicles and research of critical technology has become an important work of many large automobile enterprises and related research institutions.Energy management system has been a major obstacle to the development of electric vehicles.Especially as the energy source of the electric vehicle,the research of the power battery is particularly prominent and important.In this thesis,from the point of view of pure electric vehicle energy management,this paper proposes a control strategy of charging and discharging.Design of pure electric vehicle energy management system is not only to monitor the battery status of vehicle power battery in use,but also through the calculation and analysis of the state of charge of the battery(SOC).Through a large number of experimental data,the use of battery switch is analyzed further,and the advantage of group cell switching is verified further.This thesis has done the following work:(1)The equivalent circuit model of the battery is introduced in this theses in detail,based on that the advantages and disadvantages of various battery models have been summarized.Some methods to estimate the remaining battery power have been presented.The open circuit voltage method,current time integral method and Calman filtering method have been analyzed.Based on that,used the method of the open circuit voltage and current time integral method to estimate the remaining battery power.(2)In this theses,the overall control of energy management system is designed for the power battery,which put forward "one by one" switch mode,switch between main battery pack and standby battery pack.According to this priciple,as a preliminary judgment of the whole working state of the battery pack,the total voltage and total current of the main battery pack and the standby battery pack are collected by the Holzer sensor.The switching of battery pack is controlled by a relay.(3)On the basis of the hardware circuit,through modular and structured thinking,the software program flow chart is designed.According to the function of each module of the main control circuit of the energy management system,the software program flow chart is written.Which involves the total voltage,total current acquisition program,the remaining power estimation procedures,switching control procedures.Application of Labview integrated development environment for the preparation of the host computer interface for the battery voltage and current,remaining power of the display and data storage.(4)The battery switch condition was designed,and the switching condition of the battery was determined according to the experimental data.The fast switching discharge experiment was designed to verify the rationality of the battery switching.The battery efficiency test was designed,and the efficiency of the battery was analyzed.