Design and Implementation of a High Power Density Active-Clamped Flyback Converter

This paper presents a high power density power converter using an active-clamp flyback converter. The voltage spike in the conventional flyback converter can be eliminated to reduce electromagnetic interference and voltage stresses on power switches by using an active-clamped circuit. The relationship between zero-voltage-switching condition of high frequency power switches and magnetizing inductance and leakage inductance is analyzed and discussed. GaN devices are used both as primary and secondary switches to reduce the converter volume and switching losses, to achieve high power density. The planar transformer design reduces the conduction losses and current stresses of the secondary switches attributed to the winding configuration. With theoretical analysis and circuit simulation, a 65-W (19 V/ 3.3 A) active-clamped flyback converter with universal input voltage capability is developed and tested. The peak efficiency is up to 93% at low line voltage and the power density is 1.879 W/ cm
³
.