Design Of Fast Charge System For Lithium-ion Batteries

Lithium-ion batteries are the most widely used power packs for today's portable devices.The diversified and increasingly powerful features of portable devices have led to a rapid increase in power consumption of lithium-ion batteries and an increase in charging frequency,user has a higher charging speed requirement.For lithium-ion batteries,charging efficiency and longevity are closely related to charging methods,its fast,safe charging method is the focus of the current study.Among the many lithium-ion battery fast charging methods,the five-stage constant current charging method has been widely concerned,because it can be easily controlled,effectively shorten the charging time,extend the battery life,and close to the best charging curve of the battery.Although the method has greatly improved the charging speed and life of the lithium-ion battery,the polarization phenomenon still has an impact on the charging efficiency,time,temperature and cycle life during the charging process.These unresolved difficulties have affected the further shortening of the charging time of the five-stage constant current charging method,and the five-stage constant current charging method still needs further improvement in the elimination of polarization.In view of this problem,this paper proposes to add the depolarization measure to improve the five-stage constant current charging method.First of all,we use the orthogonal test to determine the optimal charging parameters of the five-stage constant current charging method,and add a short hold or discharge pulse at the end of each charging stage,explain the rationality of this improvement by analyzing the principle of polarization,and then carry out the lithium-ion battery charge and discharge experiments to verify the idea,at last,conduct several groups of experiments to compare the influence of the discharge and hold of different parameters on the charging time.Experiments show that discharge and hold can effectively alleviate the polarization phenomenon,shorten the charging time and improve the charging efficiency.Among them,the optimization effect of discharge depolarization on the charging time is relatively more significant.This paper designs a fast charging device for lithium-ion batteries,built-in five-stage constant current fast charge algorithm.In this paper,specific design and parameter calculation of the hardware circuit,specific algorithm and software flow chart are given.Finally,the circuit board has been completed according to the hardware design.After debugging,the experimental results show that the device has basically achieved the expected function,and can provide up to 10A charging current,the test indicators meet the initial design requirements.