Comparison of Subdomain, Complex Permeance, and Relative Permeance Models for a Wide Family of Permanent-Magnet Machines

In terms of analytical models used in the initial motor design, the subdomain (SD), complex permeance (CP), and relative permeance (RP) models are among the main ones. This article presents an analysis and comparison of these three models for a wide family of permanent-magnet (PM) machines. The finite-element models are used as a reference for comparison. The fundamental harmonic of the flux-linkage generated by the PMs is selected to evaluate the precision of the analytical model in the initial design step. The number of slots, PM pole-pairs, and ratio of tooth are selected as the key parameters to generate 749 designs for the test. The error distributions and the relationships between the error and the key parameters in the different analytical models are illustrated in this article. The SD and CP models give the best and worst results, respectively. This article also explains how to select the analytical model for the high-torque-density motors.