Implementation of the Soft Switching DC/DC Converter

Abstract

A new soft switching dc/dc converter is presented to achieve zero voltage switching (ZVS) of all switching devices. In the proposed converter, an auxiliary switch and clamp capacitor is used to recycle the energy stored in the leakage inductor, limit the voltage stress of switches and achieve resonance between the transition interval between the main and auxiliary switches. During the transition interval, the resonance based on the junction capacitance of switches and transformer leakage inductance can achieve ZVS operation of power switches. The pulse-width modulation (PWM) waveforms of two switches are generated in a complementary way with a time delay. Two modules of the series-connected transformers with center-tapped rectifier are used in the proposed converter to share the load current. Since these two modules are connected in series in the primary side and parallel-connected in the secondary side. The load current can be equally shared by these two center-tapped rectifiers. Based on the operation behavior, each transformer in the proposed converter can be operated as an inductor or a transformer. No output filter inductor is needed in the proposed converter. The circuit analysis, principle of operation, steady state analysis and design considerations of the proposed converter are provided in detail. Finally, experimental results for a 220 W prototype converter at a constant switching frequency of 150 kHz are obtained to show the performance of the proposed converter.