Equivalent circuits for transformers based on one-dimensional propagation: accounting for multilayer structure of windings and ferrite losses

In a recent paper, we linked the electromagnetic power propagation in a two-winding transformer to an electrical equivalent circuit. This study pointed out that an electrical equivalent circuit can be associated with each layer (conductor, insulator, ferrite) passed through, and that connecting all of these elementary circuits together leads to the equivalent circuit of the entire component. Propagation was assumed to be one-dimensional, and each winding was supposed to be made of a single layer of turns. In this paper, we first investigate the consequences of the multilayer structure of each winding, following the above approach. Skin and proximity effects are taken into account this way, and theoretical results are compared with experimental data. Then, we focus on the representation of the linear behavior of the ferrite core. On the basis of an experimental approach, it is shown that an accurate equivalent circuit must include a capacitor. This is consistent with the high permittivity of the material.