Research On SOC Estimation Based On Power Battery Management System

With the rapid development of automobile industry,it is restricted by energy and environment at the same time.New energy vehicles have gradually become an indispensable part of the automotive industry in today’s world and even in the future.Power batteries are the core power components of new energy vehicles.The management and use of power batteries are of great significance to electric vehicles.The estimation of SOC of power batteries is a hot and difficult issue in the research of battery management system of electric vehicles.The timely and accurate estimation of SOC of power batteries is of great significance to electric vehicles.Accurate and timely estimation of SOC value can not only increase the safety and stability of electric vehicles in operation,optimize driving performance,but also effectively prevent their own overshoot and over-discharge,thereby increasing their service life,improving utilization efficiency and using economic effects.In addition,the estimation of SOC of power batteries is also very important to the battery management system.The accurate estimation of SOC is related to the subsequent charge-discharge balancing control and optimal management of power batteries.In this paper,the common lithium batteries used in electric vehicles are studied.First,the research object is 18650 lithium batteries.The internal resistance,voltage and capacity of lithium batteries are analyzed by consulting relevant information.According to the working principle of the battery,the PNGV circuit model of the battery is established and its parameters are estimated.The PNGV model is used for the subsequent SOC estimation of lithium battery.Research and analysis of common SOC estimation algorithms for lithium batteries.After studying and analyzing the new SOC estimation method and the traditional SOC estimation algorithm.Combining the new SOC estimation algorithm with the traditional SOC estimation method,the basic principle of the Kalman filter algorithm is mainly studied.The extended Kalman filter algorithm is transformed into the PNGV model of lithium battery.At the same time,the open-circuit voltage method based on least square method and EKF algorithm are introduced to combine the SOC of lithium battery.Estimate.At the same time,a new impedance tracking technology is proposed to update the total power of lithium batteries.It can update the total power of lithium batteries under the condition of incomplete discharge,and has better practical value.The SOC joint estimation algorithm in this paper is compared with the traditional method.The battery model in matlab/simulink is used to evaluate and simulate the SOC algorithm.The accuracy of the algorithm is verified and its superiority is proved.In terms of software and hardware,TI’s BQ76940 lithium battery measurement chip and Keil5 development environment are used to design the lithium battery management system.The hardware circuit and software implementation code of battery parameter acquisition are designed respectively.At the same time,the SOC estimation algorithm is designed in Keil with the measured parameters,and the SOC estimation of lithium battery is carried out.Finally,the measurement of lithium battery parameters and SOC estimation using parameters are realized.