Hybrid three‐level PWM and resonant converter

Abstract

A hybrid soft-switching converter including two resonant circuits and an un-regulated dc-dc pulse-width modulation (PWM) circuit is presented. Two split capacitors with four active switches are used at primary side to limit power switches at V in /2. The variable frequency operation is adopted to regulate output voltage. Two flying capacitors are also adopted at the primary side to automatically balance two input split voltages. One un-regulated PWM converter shared the same power switches of two resonant circuits is used to reduce the output current ripple. Therefore, the power rating of power semiconductors and passive components are reduced. The operation principles, performance and effectiveness are illustrated and verified on a 1.44 kW (48 V/30 A) prototype circuit.