Study On Key Techniques Of Charging System For Electric Buses

This dissertation aims at the project of "Electric Vehicles Charging System for 2008 Beijign Olympic Games" and studies the key techniques to provide supports for charging system's construction theoretically and practically.A method for the analysis of the charging system capacity requirement is proposed, which is based on the electric buses parameters and the battery charging mode.By using this method to analyse and predict the capacity requirement before construction,the over design can be avoided and the optimized distribution capacity requirement and the construction cost can be achieved.The design of the abovemetioned project is carried out by using the proposed method.The charging system will inevitably pollute the power supply network.A harmonic simulation model for high frequency chargers and a harmonic analysis model for charging station are proposed,which are useful to the analysis and prediction of harmonic pollution and the design of pollution restrain methods.A simulation based on the electric buses parameters and charging mode is carried out.In recent years,a cluster of full-bridge phase-shifted ZVZCS dc-dc converters has aroused researchers' interests which suit for medium and large power stage applications using IGBTs.The operating principles and dynamic characteristics of a CDD clamped FB-PS-ZVZCS converter are studied in detail and the steady state simulations are carried out in Matlab/Simulink.Based on the study of the soft switching characteristics of the converter,an optimized parameter design procedure is proposed.Since the converter's leading leg switches' ZVS range subjects to some limitation,two improvement methods,auxiliary resonant net circuit and active auxiliary commuting circuit and a modified CDS clamp circiuit are proposed.The operating principles, parameters design method and simulations are proposed.A prototype of electric vehicle charger for 2008 Beijing Olympic Games is designed and fabricated,based on the studied converter topology.The major parameters and the digital signal controller based control system are proposed.The experimental results validate the analysis conclusions of the converter.Furthermore,the proposed modified converter is validated by the experiment.