Design And Implementation Of Battery Management System Of The Electric Vehicle

With the development of science and technology,people improve the quality of life gradually and car have started to be an essential transportation in the daily life.The use of diesel locomotive will increase the pressure of fossil energy consumption with destruction of the atmospheric environment by tail gas and threat of human health.Due to zero tailpipe emissions,low noise and high efficiency,electric vehicles have been recognized more in the society.In the process of development of electric vehicle,there are many problems that need to be studied deeply,one of which is the Battery Management System(BMS)technology.This paper discusses and analyzes the technology of battery management system of li-ion battery.The main function of the battery management system is meeting the needs of the vehicle for energy management,monitoring the battery's various information,dealing with the battery fault,communicating with the upper computer and protecting the battery.In this paper,we also analyze the estimation method of the battery's State of Charge(SOC)and the battery balance problem.The SOC iterative estimation algorithm considering the influence of balance current and the energy transfer balance topology based on switch matrix are proposed.This paper introduces the background and significance of research firstly,and it expounds the foreign research related to the design and algorithm of battery management system and the paper's research content.Then thie paper studies the electrochemical principle of lithium ion batteries.The Thevenin equivalent Circuit model is set up.We conduct the HPPC experiments to determine the relation between Open Circuit Voltage(OCV)and State of(SOC).Next,we discusses two core technologies of the battery management system which are SOC estimation and battery balance.In this paper,the traditional SOC estimation method is studied and we proposed the SOC iterative algorithm considering the influence of balace current based on Thevenin equivalent circuit model.For the balance problem,this paper analyzes the traditional battery balance topology.we uses switch matrix and DC/DC transform as balance topology and propose the balance strategy after simulation.The hardware and software parts of BMS have been designed.The whole system architecture is divided into lower-level Battery Monitoring Unit(BMU,referred to as the Slaver Control usually)and the top-level Battery Control Unit(BCU,referred to as Master Control usually)through the microprocessor to control the logical parts processing.It has realized the battery information detection,security protection,communication and other functions.The driver software is written with planning running process and the work of each module of the system has been realized.Finally,we analysis the actual measured data results with theoretical data and simulation to verify the battery voltage and current accuracy,precision,SOC balanced efficiency are in line with expected function.At the same time,it also puts forward some suggestions to improve the future work.