Design Of Battery Management System Based On STM32

New energy electric vehicles use batteries as energy sources and motors as driving sources.The battery management system(BMS)as a controller to ensure the safe and reliable operation of the power battery,its importance is self-evident.Due to the high manufacturing cost of battery management system of high-speed electric vehicle,functional redundancy is not suitable for low-speed electric vehicle.Aiming at the development of battery management system of low-speed electric vehicle,this paper develops the related technology and designs the product.Firstly,this article studies the working characteristics of lithium battery,including charge and discharge,internal resistance,temperature and so on,and analyzes and compares the electrochemical model and equivalent circuit model of lithium battery,and selects the Davinan equivalent circuit model as the lithium battery model of this design.Secondly,the main functions and overall design of BMS are described in detail,and the hardware and software system that meet the cost requirements of low-speed electric vehicle are designed according to the application requirements.The hardware system adopts the master-slave architecture,and designs the power circuit,charging circuit,battery parameter acquisition circuit,communication circuit and relay drive circuit.The software system mainly adopts the architecture of bottom layer,function module layer and application layer,and designs the common software functions of BMS,such as battery data processing,fault diagnosis,etc.Then this article focuses on the analysis and research of the accurate estimation of the residual power in the battery management system and the problem of SOC jump and SOC not 0% at the discharge end.By analyzing and comparing the existing SOC estimation algorithm,this design chooses the estimation method based on ampere hour integral and open circuit voltage correction to estimate SOC.At the same time,the dynamic following strategy is proposed to eliminate the harm of SOC jump to driving safety.Aiming at the problem that SOC is not 0% at the end of discharge,a strategy of zero calibration at the end of discharge is proposed,that is,the problem that SOC is not 0% at the end of discharge is solved by changing the speed of SOC display value.Finally,a simple testing tool and upper computer system are designed to verify the functions and performance indexes of the battery management system.The results show that the low-cost design scheme can meet the basic functional requirements of the battery management system,such as charge and discharge management,fault management,SOC calculation,communication,etc.,and also meet the requirements of the voltage acquisition accuracy and current acquisition accuracy while realizing the functions Be able to meet the requirements of indicators.Simulink simulation is used to verify the dynamic follow strategy and end zero calibration strategy of SOC.The results show that the SOC algorithm can solve the engineering problems of SOC jump and SOC not 0% at the end of discharge,which has a certain engineering application value.