Soft-switching techniques in PWM converters

A number of soft-switching pulse-width-modulated (PWM) converter techniques have been proposed, aimed at combining the desirable features of both the conventional PWM and resonant converters while avoiding their respective limitations. In this paper, three classes of zero-voltage soft-switching PWM converters (namely the zero-voltage switched (ZVS) quasi-square-wave converters, ZVS-PWM converters, and zero-voltage-transition PWM converters) and two classes of zero-current soft-switching PWM converters (namely the zero-current-switched PWM converters and zero-current-transition PWM converters) are reviewed; their merits and limitations are assessed. Experimental results of several prototype of converters are presented to illustrate each class of converter