Research of multistage charging method for onboard lithium battery of electric vehicles

CHEN Chao， XIE Rui， HE Xiangning
（College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China）

Abstract: In order to achieve the fast charging and discharging of the onboard lithium battery of electric vehicles(EV), the multistage charging method of the EV lithium battery was investigated and the charging circuit topology was presented. The method combined three charging methods (constantcurrent method, constantvoltage method and lowcurrent method) was used to control a power converter by monitoring the battery voltage and current for intelligent fast charging. The experimental results indicate that the battery voltage can reach the rated value in 30 minutes as being charged by the system, then the battery will soon be fully charged by using the constantvoltage method. The research lays the foundation for the improvement of the charging efficiency and the charging security of the onboard batteries.
Key words: electric vehicles(EV) battery; charging circuits; charging methods; control