ZVS-Interleaved Synchronous Buck DC–DC Converter With a Coupled Inductor by Varying Switching Frequency and Deadtime

This article proposes a fully digital variable switching frequency and deadtime control method for a synchronous rectifier buck dc–dc converter with an inverse coupled inductor. It does not need auxiliary circuits, zero-crossing detection (ZCD), or high-bandwidth sensors. Even in facing the polyline shape of the current in inductors due to the coupling effect, zero-voltage switching (ZVS) can be achieved with the proposed varying switching frequency control to make the turn off current be constant. Based on ZVS achievement of the power switches, the deadtime is variable to reduce the conduction loss over body diodes further. The modes and resonant process are analyzed in detail. A 1-kW experimental prototype was built to verify the effectiveness of the proposed control method. The peak efficiency is over 99% in the experimental test.