An Approximation Model of AC Resistance for Inductor and Transformer Windings with Partial Layers

Abstract

This paper proposes an approximation model of the AC resistance for windings with partial layers. It introduces the concept of the number of layers for the partial winding without theoretical support. It is simpler compared to the original partial layer equation and and has a good accuracy. The error between the approximation and the original equation is derived and compared analytically. The approximation method is verified in two case studies with simulation results of the finite element method and experimental results. Based on the approximation equation, an optimization method is proposed for the winding with partial layers. This can provide a minimum AC resistance within the design restrictions and can be applied to inductors and transformers. Finally, the optimization method is verified in a case study of a 20kHz transformer winding design.