Waveform dependent switching losses in flyback transformer foil windings

The copper losses in a foil wound flyback transformer are examined using a time domain 2-D finite element model. The purpose of the study is to examine the losses as a function of switching waveform. It is shown that the windings carry nonnegligible induced current at times when the net current in the winding is zero. As with eddy current core loss, the copper loss is shown to be functionally dependent on the time rate of change of flux density.