Design Of Digitally Controlled Electric Vehicle On-Board Charger

On-board charger,as the key charging devices of electric vehicle,is related to the power source of electric vehicle.High-performance on-board charger can effectively extend the life of the car battery and improve the utilization rate of electric energy,which is of great significance to the development of electric vehicle industry.With the development of digital controllers,digital control has more advantages than analog control in terms of flexibility,reliability,integration and so on.In this thesis,the research focuses on the digitally controlled on-board charger.Based on the research of the existing scheme and main technologies of on-board charger,a two-stage on-board charger scheme composed of Boost-PFC converter and full-bridge LLC resonant converter has been constructed.The main circuit of Boost-PFC converter has been designed,and its operation principle is analyzed.A practical design method of boost inductor has been given.A duty cycle predictive PFC control algorithm has been studied.The algorithm has the advantages of small calculation amount and fast response,which can give full play to the advantages of digital control.The simulation model of the algorithm has been established based on the main circuit parameters,the validity of the algorithm and the correctness of the parameter design have been verified.The operation principle and characteristics of full-bridge LLC resonant converter have been analyzed.On this basis,the main circuit of the converter has been designed,and a practical design method of the magnetic integrated transformer has been given.The simulation model of the converter has been established to verify the correctness of the design parameters.In the control of the latter stage converter a two-stage charge control strategy with constant current and constant voltage has been designed and soft start strategy are designed.The hardware control circuit and software program of the on-board charger have been designed.The experimental prototype has been completed and tested under laboratory conditions.The experimental results demonstrate the effectiveness of the proposed design.