Distributed Multilevel Current Models for Design Analysis of Electromagnetic Actuators

Abstract

This paper presents a generalized source modeling method, referred here as distributed multilevel current (DMC) models, utilizing equivalent magnetizing currents as local point sources to describe material effects of commonly used magnetic components. Unlike existing numerical methods, which solve for the magnetic fields from Maxwell's equations and boundary conditions, the DMC-based method develops closed-form solutions to the magnetic field and force problems, while allowing tradeoffs between computational speed and accuracy using a multilevel structure to discretize geometry and minimize modeling errors in the neighborhood around the point sources. Typical DMC models for volume and surface current elements, permanent magnets, electromagnets, iron plate, and induced eddy currents are derived and validated by comparing their magnetic fields and forces with known (analytical, numerical, and/or experimental) solutions. Results of benchmark comparison demonstrate that the DMC methods reduce the computation time of magnetic fields and forces by several orders as compared to exact solutions numerically integrated from the Biot-Savart law and Lorentz force equation and finite-element analysis. The DMC models were experimentally applied to identify the EM coil position and PM magnetization of a commercial PM linear synchronous motor validating their effects on its torque ripple.