Analysis, design and implementation of soft switching in a synchronous converter

This paper analyzes the steady state operation of a Synchronous Soft Switched Buck Converter which has the advantages of both synchronous switching and soft switching. This topology employs an auxiliary circuit to achieve soft switching. The auxiliary circuit consists of a dependent voltage source, an auxiliary switch, a resonant diode, a resonant inductor and a resonant capacitor. The dependent voltage source is realized by a mutually coupled inductor. In this topology, the switching transitions of the active switch, the synchronous switch and the auxiliary switch are lossless. The design guidelines are presented and a 33 Watt converter is designed, simulated and fabricated to validate the operation of the converter. A microcontroller is used to generate the switching pulses. An improvement of 6% in efficiency is observed over traditional topologies.