Accurate Prediction of Magnetic Field and Magnetic Forces in Permanent Magnet Motors Using an Analytical Solution

This paper presents an analytical model suitable for analyzing permanent magnet motors with slotted stator core. By including the effect of the interaction between the pole transitions and slot openings, the model is able to predict the airgap field and magnetic forces with high accuracy, which cannot be achieved using the previously available analytical methods. The results of electromagnetic forces, i.e., the cogging torque and unbalanced magnetic pull, computed analytically agree well with numerical simulations using the finite-element method. The model is used to analyze the magnetic forces developed in permanent magnet brushless motors when the design parameters vary in wide ranges. The model is useful in design and optimization of permanent magnet motors.