Modeling of Losses and Current Density Distribution in Conductors of a Large Air-Gap Transformer Using Homogenization and 3-D FEM

A large air-gap transformer has a strongly inductive behavior, and leakage flux is very important. In some cases, in order to improve the coupling coefficient of a large air-gap transformer, it is interesting to have a low turn number and a large winding window. As a result, coils are composed of a large number of conductors in parallel. Moreover, leakage flux is very important in winding windows. Therefore, losses and current density distribution in coils are not uniform. This paper presents a study of current density distribution and losses in a large air-gap transformer composed of two E cores and two windings using homogenization and 3-D FEM. Moreover, solutions to improve current density distribution are proposed.