Research On Five Stage Constant Current Fast Charging Method Of Li-ion Battery Based On Improved Taguchi Method

Environmental pollution problems and energy crisis become increasingly serious,which affect the sustainable development of the vehicle industry.Electric vehicle is a green and economical means of transport,and it has gradually won the market and is widely used in recent years.Power battery is an important energy storage component of electric vehicle,and its performance,the charging and discharging characteristics are closely related to the normal operation and good working of electric vehicle.Lithium-ion battery is being widely used as the energy storage component of electric vehicle,and it is very important to study the efficient and safe fast charging method of Lithium-ion battery.The existing fast charging method has a high charging speed,but it still needs to be further improved in balancing the charging efficiency and eliminating polarization.The five stage constant current fast charging method based on improved Taguchi method(ITM)was mainly studied in this paper,in which the fuzzy control technology was used to eliminate the polarization of the battery so as to improve the charging speed and charging efficiency,reduce the maximum temperature rise of the battery and prolong the service life of the Lithium-ion battery.The details of the study are as follows:1.With Lithium-ion battery as the research object,the working principle,the charging and discharging characteristics and the influencing factors were analyzed,the production mechanism,principle and elimination method of Lithium-ion battery polarization were studied.2.The advantages and disadvantages of the existing fast charging methods were introduced,the difficulty of improving the charging efficiency of Lithium-ion battery with high current was analyzed.The principle of five stage constant current fast charging method was researched emphatically,a method was researched and adopted,that is to determine the optimal values of the five stage constant currents by TM orthogonal experiment technology and Lithium-ion battery's RC equivalent circuit model,and to achieve the depolarization of the battery by adding intermittence and negative pulse in time.3.The determination of polarization degree and the depolarization method were studied.In this paper two fuzzy controllers were designed to decide the timing of giving negative pulse and the width of the negative pulse depolarization respectively.The optimized charging patterns of five stage constant current fast charging method based on improved Taguchi method,such as the five stage current optimization values,intermittent duration and amplitude of negative pulse,depolarization time and negative pulse width were determined by experiments.Finally,through the contrast experiments,the effectiveness of Lithium-ion battery five stage constant current fast charging method based on improved Taguchi method was verified.Compared with the traditional five stage constant current charging method and five stage constant current fast charging method based on TM,this method can shorten the charging time by 33.9% and 8.8%,increase the charging efficiency by 1.0% and 0.5%,and decrease the maximum temperature rise by 26.3% and 17.6% respectively.4.The block diagram of five stage constant current fast charging system of Lithium-ion battery based on ITM was established,the main circuit,sub-circuit of each composition and parts of software implementation diagram were designed,and a hardware experimental platform of Lithium-ion battery was built to test the function of five stage constant current fast charging system for Lithium-ion battery.The study in this paper can be applied in the systems including electric vehicles with power batteries as energy storage devices,portable electronic equipments,uninterruptible power supply(UPS),and etc.