Development Of Control System For Large Capacity DC Charger Of Electric Vehicle

Based on the dual pressures of energy crisis and environmental pollution,it is imperative for traditional internal combustion engine vehicles to transform into new energy vehicles.As an important part of the new energy automobile industry,the performance of electric vehicle DC charger directly affects the development of new energy automobile.For a long time,the development of charging infrastructure industry in China is relatively lagging behind,and there are phenomena of mismatch and incompatibility between chargers and electric vehicles.In January 2016,the National Standard Committee published five new standards for charging facilities,namely,“Electric Vehicle Conductive Charging System Part 1: General Requirements”,“Electric Vehicle Conductive Charging Connector Part 1: General Requirements”,“Electric Vehicle Conductive Charging Connector Part 2: AC Charging Interface”,“ Electric Vehicle Conductive Charging Connector Part 3: DC Charging Interface”,“Communication Protocol between Electric Vehicle Non-Vehicle Conductive Charger and Battery Management System”.The introduction of these five latest standards marks that the country will accelerate the construction and development of charging infrastructure.This project comes from Jilin Province Science and Technology Development Plan project "Development and Application of DC Charger Based on Self-positioning Function of Dual Trading Platform".The main research contents are as follows: According to the requirements of the new national standard and users' needs,this paper analyses the functions of DC charger from four aspects: the general requirements of DC charger,DC charging interface,control guide circuit,communication protocol between charger and battery management system,and sets the desired goals.According to the expected goal,the overall design of the charger system is completed,including the design of the electrical system and the design of the control system.According to the actual functions,the charger control system is divided into five modules: relay protection module,central control module,signal conversion module,human-computer interaction module,temperature and humidity regulation module.Modular design is to reduce the difficulty of device selection,electrical wiring and software development.According to the framework of the control system,the central control board needs to communicate with touch screen unit,card reader unit,integrated measurement unit,charging unit,watt-hour meter unit,lightning arrester unit and vehicle battery management system respectively.To meet the above requirements,A central control board was designed based on 32-bit ARM processor LPC1788.And the minimum system circuit and peripheral communication circuit are designed.Based on the central control board,an embedded software development platform is designed.The RTX real-time operating system is transplanted in Keil uVision 5 development environment,and the program is developed with modular programming idea.In the process of program development,the communication between each module and controller is programmed into different tasks.According to the charging process and communication protocol stipulated in the new national standard,the charging process flow chart and the task program flow chart are designed.Finally,in order to verify the charging performance of DC charger,the whole charger test bench was built.The charging control function,human-computer interaction function and card swiping payment function of charger were tested.The test results show that the control system of DC charger has normal function,stable operation and good man-machine interface,and achieves the expected design goals.