Research On Lithium-ion Battery Fast Charge Method Based On Intelligent Control

With the increasing quantity of automobile in our country,the resulting tail gas pollution has aroused general concern from all walks of life.The development of clean and environmentally friendly new energy vehicles has become an urgent demand.At present,new energy vehicles have the problems of long charging time,low efficiency,and short cruising range.which is mainly due to the serious polarization of batteries caused by unreasonable charging methods.In order to improve this problem,a fast charging method for lithium battery based on fuzzy adaptive PID control is designed.The research of this problem accords with the demand of the current electric vehicle development,and has a positive effect on the development of electric vehicle industry.The main work of this paper consists of the following three parts:First,the internal factors affecting the charging of lithium battery were studied by using18650 model of lithium iron phosphate battery as dynamic battery model.Aiming at the influence of ohmic polarization,concentration polarization and electrochemical polarization of lithium battery during charging,the model of GNL battery is established.In the model,three corresponding modules are designed for the three kinds of polarization respectively,and a more accurate battery model is used to reduce the effect of the three polarization on charging.Secondly,on the basis of analyzing the advantages and disadvantages of the traditional charging methods,an improved three-stage fast charging method combining constant current,positive and negative pulse and constant voltage is designed.Aiming at the influence of three external factors,such as polarization,temperature change and charging frequency,on the charging process,the charging method is optimized and designed.In the charging scheme,voltage drop compensation is added to improve the effect of polarization,and temperature compensation is added to eliminate the effect of temperature change on charging;the optimal frequency of different stages of charging is found by perturbation observation method,and the effect of non-corresponding frequency is eliminated.Finally,the control strategy of fuzzy adaptive PID is designed to solve the problem that the parameters of charging system can not be adjusted by themselves,aiming at the problem that the charging control parameters can not be adjusted in real-time online when the environment changes and the difficult to realize the real-time accurate control of chargingsystem.The effectiveness of the designed control scheme is verified by MATLAB simulation,the software and hardware of the rapid charging system are designed and selected,the overall simulation of the charging system is carried out,which verified the advantages of short charging time,high dynamic performance and good stability.