Design And Implementation Of High-Power Electric Vehicle DCCharging System

Recently,Chinese car owership showed a trend of geometric growth with the rapid economic development,the improvement of people's living standard and urbanization level.Which not only result to serious threat to the national energy security,but also aggravate the deterioration of the environment climate,so the large-scale development of the EV(electric vehicle)industry become the inevitable trend.The energy supply facilities of EV are the premise and foundation of EV industry developing,complete and efficient energy supply net is a key factor in the popularization of EV,DC charging system which has good rapidity is the emphasis in the energy supply facilities of EV.And with continuous increasement of the requirement for the range of EV,high power is the trend of DC charging system.The thesis focused on high power DC charging system and 120 KW DC charging system prototype has been developped.DC charging system is geared to the needs of various types of EV,so its functions and performance must meet the new 5 charging standards in order to guarantee the compatibility and reliability.The general plan design of DC charging system has been completed and it has been divided into power regulation subsystem and management control subsystem based on its functions in the thesis.The main fuction of power regulation subsystem is to convert three-phase power to DC power which is required by power battery in order to meet the charging requirement.An intelligent mater-slave current sharing scheme which is based on CAN is designed for the current sharing problem that is caused by the multiple power modules paralleling,which results that current-unbalance belows ±5%.And a autonomous cut-in strategy is designed on the basis of the characteristics of power module,which has improved the efficiency of DC charging system at light load observably.The main function of management control subsystem is to guarantee the intellectualization,the reliability and orderliness of the charging process by the controller communicate with and drive control the other components.The thesis designs a controller based on STM32F107VCT6 and designs the architecture of the application program.Then,the power unit information interactive program,the BMS information interactive program,the energy metering unit information interactive program,the HMI unit inforamtion interactive program and the information acquisition and drive control program are designed in detail according to the interface type of the controller.Developed 120 KW DC charging system has been tested comprehensively at a national center,all performance indices meet the new 5 charging standards and sevice requirements.