A ZVS technique for single-switch PWM converters implemented with paralleled MOSFETS

It is common practice to implement the main power switch in single-switch, pulsewidth modulated (PWM) converters as a combination of parallel MOSFETs to reduce conduction losses. This is done in higher power applications where high switching frequency operation is required and a significant amount of current flows in the converter. An auxiliary circuit is typically used to help the main power switches turn on with zero-voltage switching (ZVS), but previously proposed auxiliary circuits are limited in power and are not suited to higher power applications. In the paper, a new auxiliary circuit that can be used in applications where paralleled MOSFETs are used is proposed. The operation of a boost converter operating with the new auxiliary circuit is described, and general guidelines for the design and implementation of the converter are given. The feasibility of the auxiliary circuit is confirmed by experimental results obtained from a boost converter prototype.