Optimization of a flyback transformer winding considering two-dimensional field effects, cost and loss

Abstract

The largest loss in an example litz-wire flyback transformer is found during current commutation between windings. In order to reduce this loss, a new optimization method is introduced. The new method optimizes strand size and number in litz wire considering cost and loss. Unlike previous methods, it is valid with two- or three-dimensional field geometry and with different nonsinusoidal waveforms in any number of windings. The result of applying this method to the example flyback transformer is less expensive designs with lower loss, as confirmed by experimental measurements.