Soft switching forward-flyback converter with one magnetic component and current doubler rectification circuit

An active clamped forward-flyback converter comprizing a current doubler scheme, which allows to boost the application range of MOSFETs for efficient rectification in low-voltage power supplies, is investigated first approximatively and second incl. commutations. Design equations and issues are given for the magnetical integration of filter inductors on the outer core legs of the transformer . The circuit allows soft switching in the relevant operation range, while keeping the reactive power low. Thus, the resulting efficiency of nearly 90% using Schottky diodes is increased compared to hard switching or resonant topologies.