Abstract
This dissertation provides the analysis and comparison of these converters;it also refers to the improvement of these converters.The ZCS condition can be obtained by introducing an auxiliary circuit into the primary or secondary side.However,these converters introduce other questions too.The auxiliary circuit which consists of loss component or active switch costs the overall efficiency.Converter with tapped inductor or transformer makes the converter somewhat complex and the core loss is inevitable.Converter with snubber circuit seems a good choice and brings a duty cycle boost effect;however,it increases the voltage stress of the secondary rectifier diodes.Based on the analysis of principles of ZVS and ZVZCS converter,a new topology with two diodes and a capacitor in the auxiliary circuit is proposed to overcome these questions. The results show that the converter achieves soft switching easier than conventional converters with fewer components in the auxiliary circuit . Finally drawwing on the basic topology of the literature , I design a simple FB-ZVZCS-PWM converters, and made a to prove the theory is right.
Keywords phase-shift，full bridge，ZVS，simulation by PSIM
