Optimization of a Flyback Transformer Winding Considering Two-Dimensional Field Effects, Cost and Loss

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 twoor three-dimensional field geometry and with different non-sinusoidal 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.