Modelling and teaching of magnetic circuits

Abstract

In the analysis of magnetic circuits, reluctances are commonly modeled as resistances and magnetomotive forces modeled as electromotive forces. In this way the magnetic flux and flux density can be determined easily. However, a close examination should reveal that it is fundamentally wrong to use a resistance, which is a lossy component, to model reluctance, which is a lossless component. This confusion may result in serious problems in the analysis and computer simulation of mixed electric and magnetic circuits. The gyrator approach of modeling can resolve the problem. However, due to the unwillingness of electrical engineers to accept the term gyrator, it has never been widely used. In this paper we propose to revitalize the gyrator model and to further develop it into a z-parameter model. Since z-parameters are well-defined parameters of the 2-port networks, engineers/students in the electrical engineering discipline should find the z-parameter model much easier to understand and to manipulate. In addition, we also propose some strategies to introduce the z-parameter model of magnetic circuits into the curriculum of electrical engineering courses.