Magnetics and Magnetic Equivalent Circuits

Abstract

This chapter is to set forth the basic background needed to analyze electromagnetic and electromechanical systems. After the review of magnetics, the notion of magnetic equivalent circuits (MECs) will be explored as an approximate but often fairly accurate technique for the analysis of magnetic systems. Magnetomotive force (MMF) in magnetic circuits is analogous to electromotive force in electric circuits. The chapter aims to derive Kirchhoff's MMF law for magnetic circuits and Kirchhoff's flux law for magnetic circuits. All network reduction techniques the reader is accustomed to for electric resistive circuits also apply to magnetic circuits. The chapter considers the relationship between the MEC and the corresponding electric equivalent circuit. Inductance is a metric associated with the flux linkage versus current characteristic of a magnetic device. Fringing flux is associated with air gaps in a magnetic circuit. Leakage flux refers to flux that is flowing outside of the intended path in a magnetic circuit.