Analysis and Design for a Novel Single-Stage High Power Factor Correction Diagonal Half-Bridge Forward AC–DC Converter

By means of components placement, the buck-boost and diagonal half-bridge forward converters are combined to create a novel single-stage high power factor correction (HPFC) diagonal half-bridge forward converter. When both the PFC cell and dc-dc cell operate in DCM, the proposed converter can achieve HPFC and lower voltage stress of the bulk capacitor. The circuit analysis of the proposed converter operating in DCM+DCM mode is presented. In order to design controllers for the output voltage regulation, the ac small-signal model of the proposed converter is derived by the averaging method. Based on the derived model, the proportional integral (PI) controller and minor-loop controller are then designed. The simulation and experimental results show that the proposed converter with the minor-loop controller has faster output voltage regulation than that with the PI controller despite the variations of line voltage and load. Finally, a 100-W prototype of the proposed ac-dc converter is implemented and the theoretical result is experimentally verified