DCM analysis of a single SiC switch based ZVZCS tapped boost converter

The analysis of discontinuous conduction mode (DCM) for a novel single active switch based zero voltage and zero current switching (ZVZCS) tapped boost converter is proposed in this paper. The ZVZCS converter includes a lossless snubber composed of three diodes and two capacitors, and exhibits novel ZVZCS operation for wide operating ranges of duty cycle, load current, and input voltage. The voltage stress of the active switch is always less than load voltage, and soft switching turn-on and off is achieved without cumbersome current or voltage sensing, which could not have been obtained from quasi-resonant converters that also have an active switch. A detailed analysis for the DCM and the design procedures of the proposed converter are presented. Experiments for a 450 W prototype show 99.0% of maximum efficiency with a SiC JFET at the switching frequency of 50 kHz, and the ZVZCS operation is guaranteed even for the DCM under the experiment conditions.