A zero-voltage-switched PWM boost converter with an energy feedforward auxiliary circuit

A zero-voltage-switched (ZVS) pulsewidth-modulated (PWM) boost converter wi th an energy feedforward auxiliary circuit is proposed in this paper. The a uxiliary circuit, which is a resonant circuit consisting of a switch and pa ssive components, ensures that the converter's main switch and boost diode operate with soft switching. This converter can function with PWM control b ecause the auxiliary resonant circuit operates for a small fraction of the switching cycle, Since the auxiliary circuit is a resonant circuit, the aux iliary switch itself has both a soft turn on and turn off, resulting in red uced switching losses and electromagnetic interference (EMI). This is unlik e other proposed ZVS boost converters with auxiliary circuits where the aux iliary switch has a hard turn off Peak snitch stresses are only slightly hi gher than those found in a conventional PWM boost converter because part of the energy that would otherwise circulate in the auxiliary circuit and dra stically increase peak switch stresses is fed to the load. In this paper, t he operation of the converter is explained and analyzed, design guidelines are given, and experimental results obtained from a prototype are presented . The proposed converter is found to be about 2%-3% more efficient than the conventional PWM boost converter.