A Study On Vehicle Digital Power Supply For Lithium Battery Motor Vehicle

In present times,energy crisis and Air pollution caused by motor vehicle are increasing seriously,electric vehicles,as a non-polluting transportation tool,will have great advantages.The kind of pure electric vehicles powered by lithium battery has become the focus of international competition.However,the development and popularization of charging station and charging pile are influenced by many factors,such as the cost of electric vehicles and charging station running,etc.Therefore,the study of vehicle charging power has a profound practical significance and economic price.The thesis intends to systemically research the charging power supply for charging up the lithium battery electric vehicles,and design a 3KW digital charging power.The whole scheme of digital power factor correction and full-bridge converter circuit structure are introduced.Because the traditional analog PFC control method has many disadvantages,we propose the digital PFC control technology which has the advantage of resisting disturbance,high reliability,and realizable plurality control,which make the tendency that analog control can be replaced by digital control.The vehicle charging power design consists of two parts:hardware and software.Hardware design consists of:the main circuit, the main control circuit,PWM driver circuit,sampling circuit,communication circuit and auxiliary power supply design.In the main circuit,differential mode and common mode choke,PFC circuit and full bridge converter are mainly designed;in the main control circuit,Microchip's dsPIC30F6010,as the main control chip,combined with Xilinx's XC9500 series CPLD is used to complete the charging power control;PWM driver circuit enhances its driving capability by using the totem pole drive mode;sample conditioning circuit completes the sample of main circuit parameters and achieve a variety of protect function by means of Hall voltage and current sensors;data is communicated in communication circuit with PC by CAN bus,in order to achieve battery management system (BMS);In the part of auxiliary electric power supply,we take a group of electric power supply as the foundation,and design five groups of power to achieve power isolation.The software part design mainly contains two parts:first,digitalized PFC software design;second,full bridge converter software control.Finally,a summary for this paper is made,and the merit and insufficiency about this design are pointed out,which have provided references for further research.