Research On The Optimization Fast Charging Method Of Lithium-ion Battery With Intermittent-positive And Negative Pulse

People deeply realize the importance of protecting the environment because of thebad climate which caused by the increasingly serious environmental pollution. The traditionalautomobiles using fossil energy are disputed because of the exhaust does great harm tothe environment. The energy conservation and emissions reduction fuel vehicle, EV andHEV are noticed by people because of the performance, low exhaust and mileage andother advantages. They developed rapidly. Power battery is the power source of HEVand EV. The power battery charging technology is very important for the applicationand development of HEV and EV, so it becomes a research hotspot of clean energy inthe automobile industry.There is a polarization in the battery charging process. Polarization has influenceon the charging efficiency, charging time, temperature and cycle life of the battery. Butthese methods can’t switch the work mode according to the different needs of the work.Eliminating polarization effect is not obvious. So traditional fast charge method needslong time and its efficiency is poor. These made the battery damage and caused the lackof energy and environmental pollution. Based on the study of traditional fast chargingmethod, this paper improves the traditional method and uses the intermittent-positiveand negative pulse charging method. The main research contents are as follows:1. This paper chosen the lithium-ion battery as the research object analyzed theworking principle of lithium-ion battery and the polarization phenomenon of thelithium-ion battery in the charging process. Particularly it analyzed the polarizationphenomenon effect on lithium-ion battery charging process.2. Based on the study of traditional fast charging method, comparing the solutionof the depolarization，improves it and uses the intermittent-positive and negative pulsecharging method. Through the different condition to judge battery during chargingprocess and choose an appropriate charge current. Timely add batch and negative pulsesfor depolarizing.3. Analysis the influence of concentration polarization, chemical polarization andohmic polarization on the charge process. Research on determine the degree ofpolarization and the method of eliminating polarization methods. This paper designedfuzzy controller1and fuzzy controller2to determine the depolarization given time anddepolarization negative pulse width respectively. The charging process has been in thebest condition. The intermittent-positive and negative pulse charging method wasverified by the experiment, the analysis results show that, this method can improve thecharging efficiency, shorten the charging time.4. This chapter designed the hardware circuit and software flow chart of thelithium-ion battery fast charging system and tested the system.The fast charge method which used by this paper is suitable for HEV, EV, electricpower bicycle and the secondary power supply of the energy storage mechanism whichused power battery.