Design study of foil winding flyback converters using 3D finite element analysis

The paper presents a finite element analysis of an E-core transducer with mixed stranded and foil windings for a DC-DC flyback converter. Both magnetostatic-and time-domain finite element analyses are applied for deriving characteristic parameters and winding power losses. The losses are caused by eddy currents in the foils, which mainly occur at high frequencies. For close-packed setups, it is shown that the winding losses are concentrated in the inner and the outer layer of the foil winding. An optimized foil winding design is developed. Comparative simulations and measurements demonstrate the increase in transducer efficiency by subdividing the foil winding.