| Abstract |
This paper deals with novel homogenization methods for theinclusion of skin and proximity effect in windings infinite-element (FE) models of electromagnetic devices. A generalfrequency-domain approach and its original extension to the timedomain are proposed. In a preprocessing step the conductors (i.e.type of cross-section and packing, and fill factor) arecharacterized in the frequency domain by means of a reduced FEmodel, producing six dimensionless and frequency-dependent skin-and proximity-effect coefficients. The latter coefficients arereadily taken into account in a frequency-domain FE analysis of acomplete device. A time-domain FE analysis with homogenizedwinding requires the introduction of additional unknowns andequations; this extension to the time domain is analogous to theapproximation of a frequency-dependent inductive impedance by aladder circuit consisting of constant resistances and inductances.By way of illustration and validation, the homogenization methodsare applied to a 2D FE model of an inductor. For the winding,different types of wire cross-section and packing, vizround/hexagonal and rectangular/rectangular, are considered. Aprecise reference solution is obtained with a FE model in whichall wires are finely discretized. An excellent agreement isachieved while reducing the computation time considerably. |
