A self core reset and zero voltage switching forward converter topology

A self core reset arid zero voltage switching (ZVS) forward converter topol ogy is presented in this paper. By employing a simple auxiliary circuit, th e proposed topology is able to achieve self reset of the power transformer without the use of the conventional tertiary reset winding, and its main sw itch can be turned on and turned off under ZVS independent of line and load conditions. This simplifies the power transformer, and the switching losse s are substantially removed to improve the overall efficiency. Steady state analysis of the circuit is performed, Based on the analysis, a design proc edure is presented, and the effects of the circuit parameters on the flux e xcursion of the power transformer are investigated to make sure self reset can be achieved without increasing the core losses. Simulation and experime nt on a 5 V, 100 W prototype circuit operated at 200 kHz are carried out to verify the design. About 5% higher overall efficiency is obtained in the p rototype converter than in its conventional counterpart.