Novel soft-switching DC-DC converter with full ZVS-Range and reduced filter requirement - Part I: Regulated-output applications

A novel soft-snitching topology for dc-dc converters is proposed. It is wel l suited for applications in the range of a few hundred watts to a few kilo watts. It is essentially a-hybrid combination of an uncontrolled half-bridg e section and a phase-shift controlled full-bridge section, realized with j ust four switches. The main features of the proposed topology are zero-volt age-switching down to no-load without serious conduction loss penalty, cons tant frequency operation and near-ideal filter waveforms, The improved filt er waveforms result in significant savings in the input and output filter r equirement, resulting in high power-density. The new topology requires two transformers and two de-bypass capacitors. The combined VA rating of the tw o transformers is more than that of the single transformer of conventional full-bridge converters, for variable-input applications. In Part I of the p aper, the converter operation is analyzed for typical switch-mode power sup ply applications, where the input voltage varies widely but the output volt age is fixed and is well regulated, Experimental results obtained from a 10 0-W/200-kHz proof-of-concept prototype confirm the superior features of the proposed hybrid configuration.