A Constant Polarization Charging Method For Li-ion Batteries Based On Fuzzy Control

In 2017,Britain,Germany,France,and other countries issued a timetable for the ban on the sale of fuel vehicles.China has also proposed a “double-integration” policy for the production and sales of fuel vehicles,and has encouraged the development of new energy vehicles led by electric vehicles.The power battery the charging polarization voltage to optimize the battery's fast charging method so that the charge-discharge characteristics of the power battery are the key factors for the performance of the entire vehicle.Lithium-ion batteries have the advantages of high energy density,low self-discharge rate,no memory effect,etc.Compared with other batteries,lithium-ion batteries have the highest market share of power batteries.It is precisely because of this that it is necessary to conduct research on the charging methods of lithium-ion batteries.This paper mainly studies the polarization characteristics of the charge and discharge of Li-ion battery,and proposes to control the charging polarization voltage to optimize the battery's fast charging method so that the charging current can adapt to the current state of charge(SOC)acceptable charging.Current.In order to improve the charging speed and charging efficiency,prolong the service life of lithium-ion batteries.This article mainly did the following research work:Firstly,we selected lithium-ion batteries as research objects,deeply understood its the polarization characteristics of lithium-ion batteries domestic and international development status and advantages and disadvantages of rapid charge strategies,and comprehensively analyzed the polarization characteristics of lithium-ion batteries and the influencing factors and the mechanism of polarization.And control difficulties,based on the study of the principle of fast charging,proposed a constant polarization fast charging method,and focused on the principle of constant polarization charging method.Then we will study how to determine the degree of polarization and how to control it.Based on the traditional RC circuit model to simulate the charging process of the lithium-ion battery,the charge current,the initial battery state-of-charge SOC,the initial polarization state,and the cycle life were analyzed,and a relationship model between the polarization voltage and the SOC was established.The relational equation used to estimate the polarization voltage of a lithium ion battery was fitted.And by using the fuzzy control algorithm to control the charging current and timely negative pulse to control the battery's polarization is constant within the current SOC threshold.The experimental comparison shows that the proposed constant polarization charging method has great advantages compared with the frequency conversion pulse charging method.Finally,the frame structure of the constant polarization charging Li-ion battery,and proposes to control the charging polarization voltage each component sub-circuit and the software part are designed.The lithium-ion separation based on fuzzy control of constant-polarization Li-ion battery charging hardware and software experiments is established.The platform tested the function of a constant-polarization charging system for a fuzzy-controlled lithium-ion battery.The proposed method based on fuzzy control of constant polarization charging has certain research significance and practical value in the fields of electric vehicle,aerospace power supply,distributed power station and so on.