A Novel Semi-Analytical Method for Foil Winding Losses Calculation Considering Edge Effect in Medium Frequency Transformers.

The design of the medium-frequency transformer (MFT) attracts increasing academic attention in recent years, in which the accuracy of the calculation method serves as the pivotal foundation. The existing 1-D based theoretical method generally fails to precisely estimate the foil winding losses under a significant 2-D edge effect. The 2-D semi-empirical methods are merely suitable for limited parameters and structures, and the pre-processing is cumbersome. The finite-element method (FEM) is accurate, yet its high computational cost makes it hard to apply in the MFT designing process. Regarding these issues, a novel 2-D semi-analytical method is proposed in this article with strict theoretical basis and sufficient generality. The foil region is divided into several rectangular elements with uniformly or linearly distributed current density, and one layer of images is placed around the magnetic core window. By deriving the basic electromagnetic relations between those rectangular elements, algebraic equations are formed with current density of the elements being the unknowns. Through the method, the whole problem turns into the process of solving algebraic equations, where all of the coefficients are obtained analytically. The new approach can achieve significantly high accuracy with acceptable computation cost, and it could suitably fit into the MFT designing process. [ABSTRACT FROM AUTHOR]