High And Low Voltage Dual Port Vehicle Charger Integrationr

On-board charger and on-board DC/DC are important components of electric vehicles.Under the strong promotion of national policies,new energy vehicles have occupied a high market share.However,as most of the on-board chargers and on-board DC/DC are two independent parts,the in-car space is insufficient and the energy conversion efficiency is low.The physical integration of vehicle charger and vehicle DC/DC can effectively solve this problem.According to domestic and foreign researches on vehicle charger,this paper integrates high-voltage output and low-voltage output of DC/DC in the same vehicle charger in different working modes,Constitute a high and low voltage output compound dual port car charger.The working principle,working mode and control method of dual port charger are discussed in detail,select totem pole PFC circuit and dual output port LLC resonant circuit as the main circuit topology of the charger.Though the design requirements of the charger,the parameters of the inductor and capacitor in the PFC main circuit are designed,LLC circuit is equivalent converted by fundamental wave analysis method,and the influence of inductance and quality factor on LLC circuit is analyzed,Thus,LLC resonator,transformer and power switch tube are selected.The control strategy and overall control method of totem pole PFC circuit and LLC circuit are studied.By establishing the small signal model of totem pole PFC circuit,the transfer function of the controlled object is obtained,and the double closed loop series control structure is designed.According to the analysis of the transfer function of LLC circuit controlled object and the application of different modes,a dual-output port control strategy is designed.A 6.6kw vehicle charger experimental prototype is designed by using a hybrid dual port circuit with high and low voltage output.Totem pole PFC circuit has high power factor,and makes dc bus voltage stable output;LLC resonantconverter has low loss,high switching frequency and wide output voltage range,so that the dual-port vehicle charger can meet the power factor and efficiency and other performance requirements.Simulation and experimental results verify the correctness of the theoretical analysis.