Frequency-domain homogenization for impedance characterization of Litz-wire transformers in 2-D finite element models

This work deals with a frequency-domain homogenization technique for Iitz-wire bundles in transformers. The approach consists in adopting a frequency-dependent complex reluctivity in the Iitz-wire bundles and a frequency-dependent complex impedance in the electrical circuit. The Iitz-wire bundles become homogeneous conductors which are easy to integrate into a finite element model of a transformer. The magnetic flux and the impedance of the Iitz-wire transformer computed from the homogenized model agree well with the reference fine model in which each Iitz-wire turn is finely discretized. The errors of the computed resistance and inductance values are less than 3% and 0.03% respectively with several times faster calculation.status: publishe