Research On Energy Equilibrium Of Lithium Battery Pack In Electric Vehicle

In order to solve the problems of environmental and energy,many countries have invested a lot of resources to research and develop electric vehicles.Lithium battery replaced the other battery because of its outstanding performance and become the driving force's energy in many electric cars.In order to achieve the required voltage and power of the electric vehicle,the lithium battery is connected in series to form a battery pack,so the battery pack is needed to be managed.In the production process of Lithium batteries,due to the limit of technology,materials,and other factors,battery of monomer between capacity,voltage and other aspects,it will affect the battery's the working efficiency when used and what's worse it may also cause accidents.These problems restrict the development of lithium battery electric vehicles.This article will focus on the battery management system(BMS),Dutch electric state of charge(SOC)estimation,battery energy balance management,these three aspects that launched research seeking to improve BMS performance.The main points can be summarized as follows:First,analyzing the development of electric vehicles to understand the importance of BMS.This paper research on the related characteristics of the lithium battery,come to a conclusion that the performance of the single cell can affect the overall performance of the battery pack,so it is very important to study the energy balance management of the battery pack.Second,analyzing a variety of BMS structure,this paper design related hardware circuit of BMS based on BQ76PL536.The detection of various parameters of the battery is completed.Third,aiming at the problem of large estimation error of SOC,analyze and compared various SOC estimation methods.This paper optimize the estimation process based on the Kalman Filter Extended(EKF)to complete the SOC estimation,and verify the reliability of the method by experiment.Fourth,analyzeing and comparised various types of equalization circuit,according to circuit reliability,efficiency and cost of the circuit,propose the DC/DC equalization circuit programme.Make sure the energy balance of the battery pack by means of the combination of resistance equalization circuit and DC/DC equalization circuit.Finally,achieve the function of BMS on the basis of the hardware circuit,and complete the BMS software design.