2D vs. 3D models to predict equivalent circuit parameters for high frequency transformers

Summary form only given. Ferrite core inductors and transformers are key components in high frequency switch mode power supplies. Finite element software tools have recently become available to extract the equivalent circuit parameters for such devices and to generate Spice-compatible models for circuit analysis and design. However, the existing extraction tools are based on 2D (pot core) approximations of actual 3D core configurations. While this approximation may be reasonable for certain core geometries, it leads to errors in others. The purpose of this paper is to quantitatively assess the magnitude of these errors in representative high frequency designs. It is shown that because of 3D effects, the extracted parameters can be significantly in error for certain geometries. This, in turn, has a major impact on the predicted electrical performance of the full power supply switching circuit.