Design Of Battery Management System For Electric Vehicles

With the gradual enhancement of people's environmental protection concepts and energy conservation concepts,electric vehicles have become the focus of attention of the whole society,and the world is vigorously developing electric vehicles.As the source of electric power for electric vehicles is clean energy,it not only satisfies people's convenient travel needs,but also reduces environmental pollution and at the same time can cope with the energy crisis.As a power source for electric vehicles,power battery packs are an important part of automobiles.However,the battery after group formation may cause various problems due to factors such as the battery itself and the working environment.Therefore,a battery management system(BMS)is required to perform real-time monitoring of the battery during operation.To ensure the safe,reliable and reasonable use of the battery pack to prevent the risk of battery failure,prolong the service life of the battery pack and increase the mileage of the electric vehicle.This paper uses lithium battery as the research object and designs the battery management system.First of all,the relevant characteristics of lithium batteries were analyzed,including discharge characteristics,charging characteristics and cycle life characteristics,and some of the thresholds for the safety protection of battery management systems were obtained.Then this article continues to elaborate the commonly used SOC estimation methods at home and abroad,and finally analyzes and determines the SOC estimation method used in this system.In order to improve the system flexibility and facilitate the expansion,the hardware of the battery management system in this paper adopts a master-slave structure to design the system.The system consists of two parts: the main control board responsible for tasks such as data processing and analysis,current acquisition,and SOC estimation,and the acquisition board responsible for tasks such as data collection and battery equalization.Data exchange and communication between two boards through the SPI bus,and the main control board communicates with the upper computer through the serial port.According to the number of batteries,the number of collector boards can be flexibly configured to realize more battery management.The main control board adopts STM32F429 with higher hardware integration,lower power consumption and strong anti-interference as the main control chip.The acquisition board adopts LTC6804-1 as the core chip of the acquisition board,which can realize high-precision voltage acquisition and resist strong electromagnetic interference.This paper designs the hardware supporting software and divides it into software design of the main control board and acquisition board.It gives the flow chart of the software design of each module and describes the working process of the main program,acquisition program,balance program and fault alarm program in detail..At the same time with LabVIEW prepared the host computer monitoring interface,can achieve the display system to collect the parameters of the value,fault alarm,data storage and other functions.Finally,the performance test of the battery management system was conducted to test the system's data acquisition accuracy and balance effect.The test results show that the designed system has high collection accuracy,good balance effect,and can run safely and stably,meet the needs of the battery management system,realize the expected functions,and has certain application value.