A soft-switching multi-phase converter with coupled inductors and switch-time-delay control

There is an increasing demand to implement soft-switching techniques to inductor coupled power converters in order to reduce their overall profiles and costs. This paper proposes a simple, low cost method to soft switch multi-phase converters. Specifically, a switch-time-delay control instead of auxiliary circuit is implemented to the positively coupled inductors. By taking the benefit of voltage coupling effect of the inductors wound on the same magnetic core, resonance between the leakage inductance and the parasitic capacitor is properly utilized during the delay time, and zero-voltage-switching (ZVS) of the power switches is achieved. In additional to detailed theoretical analysis, experimental results verify the feasibility and effectiveness of the proposed concept.