Frequency-Dependent Equivalent Circuit Parameter Calculation of Gapped Multiwinding Inductors

Accurate and fast models of the equivalent circuit elements of gapped multiwinding inductors are essential to design galvanically isolated converters such as the Flyback converter and the LLC-converter. This paper derives equivalent circuit parameters of gapped multiwinding inductors from 2D magnetic field models proposed in this paper. It is shown and quantitatively examined that frequency affects resistance and inductance values of magnetically coupled windings by several effects. Especially eddy currents in windings induced by the air gap field play a significant role besides the well known skin- & proximity effect. The proposed model accurately takes into account all these effects in foil- and round wire conductors. The model is verified with FEM simulations and measurements.