Harmonic interaction model for fast and accurate cogging torque calculation in permanent magnet machines

Abstract

This article presents a semi-analytical model for predicting cogging torque based on harmonic interaction principle within the air gap. It derives the airgap's magnetic energy through Fourier expressions of the rotor magnetomotive force in motion and the airgap permeance considering slotting effects. The analytical expression for cogging torque is then obtained by differentiating the airgap magnetic energy with respect to motion. This model is distinguished by its fast computational speed and high accuracy compared to the finite element method (FEM), making it advantageous for large-scale design optimization. Notably, the model can analyze the factors influencing cogging torque, offering theoretical insights for cogging torque reduction.