Research On Three-port Active Bridge DC/DC Converter For Electric Vehicles

With the increasing awareness of environmental protection and energy saving,interest and research in electric vehicles worldwide has increased.The on-board power converters are the core components in electric vehicles.Therefore,researches should be carried out to improve their performance.Smaller size,lighter weight,stability and reliability are of great concern.On the basis of integration technology,a three-port full-bridge DC/DC converter is proposed.By integrating the on-board charger and low-voltage DC/DC converter,this proposed converter can meet the requirements of higher power density and lower cost.It can operate in three modes:1)OBC standalone mode;2)LDC standalone mode;3)OBC-LDC simultaneous mode.Firstly,this paper analyzed the working principle of the proposed converter,including power transmission and soft switching.Secondly,different control strategies were introduced to improve the converter's performance in different modes.They are single phase-shift control,single-side PWM plus single phase-shift control and double phase-shift control,corresponding to OBC standalone mode,LDC standalone mode and OBC-LDC simultaneous mode.Thirdly,a compensation network was designed according to the model which was built by switch-state averaging method.As the most important components,the transformer and external inductors were designed by considering the soft switching ranges and the peak inductance currents.The design of the platform was consisted of hardware design and software implementation.On the hardware side,the power devices,isolating driver circuit,sampling and conditioning circuit,hardware protection circuit were designed;On the software side,the control flow chart and PWM control signal generation were implemented by processor TMS320F28335.Finally,a three-port full-bridge DC/DC converter experimental platform applied to a 3.3-kW OBC and a 2-kW LDC were constructed to demonstrate the validity and advantages of the proposed system.Experimental results showed that the proposed system can operate in three modes:OBC standalone mode,LDC standalone mode and OBC-LDC simultaneous mode,which verifies the feasibility of the proposed scheme.This paper proposes a three-port full-bridge DC/DC converter for electric vehicles(EVs)to improve the power density and efficiency at less cost.It integrates the on-board charger(OBC)and the low-voltage DC/DC converter(LDC)by common use of semiconductor devices,capacitors and magnetic components.Therefore,the volume and cost of the integrated system is reduced compared with the conventional two independent converters.Therefore,the proposed converter is of great competitiveness in the present electric vehicles market.