A Novel Mixed Planar litz Transformer for high frequency active clamp flyback converters

This paper proposes an innovative transformer for high frequency flyback converters, especially suited for GaN-based active clamp flyback converters. The proposed construction uses both planar litz and traditional windings to minimize the total losses of the transformer considering the current and the magnetic field present in each winding section. A 60 W active-clamp flyback wallcharger for the USB-C specification is designed and tested with the proposed method. Experimental results demonstrate the validity of the new technique by the comparison with a traditional planar solution applied to the same converter.