Implementation of a new ZVS DC/DC converter to extend ZVS range

Abstract

A novel zero-voltage switching (ZVS) converter is studied in this paper. The proposed converter consists a three-level converter and a LLC converter with same active switches to have wide ZVS load range and to reduce conduction losses at freewheeling interval. Series resonant converter with fixed switching frequency is adopted to improve ZVS load range of lagging-leg switches. The primary current at freewheeling state is reduced to zero by parallel connection of outputs of three-level and LLC converters. The system diagram, operation principle and circuit characteristics are presented and discussed in detail. The performance and effectiveness of the circuit are verified by experiments based on a 1.44kW circuit.