Analytical Energy-Based Approaches for Cogging Torque Calculation in Surface-Mounted PM Motors

This paper deals with the cogging torque calculation in permanent-magnet (PM) surface-mounted machines based on energy approach. Three different analytical co-energy methods are assessed, and innovative computation techniques for calculating co-energy are applied to reduce the computations time and burden. Also, an air-gap function due to the slot is presented for the simple method. Then, the results achieved by the analytical methods are validated by the finite-element method (FEM). The cogging torque using such methods has a good agreement with FEM. Three case studies consisting of brushless PM (BLPM) motors with slotted stator structure are considered to show the efficiency of the proposed methods. Finally, different methods are compared in terms of their computational complexity and accuracy.