Synthesis of Relative Permeance for Analysis and Design of Multislotted Surface-Mounted Permanent Magnet Motor

Abstract

This article presents an analytical method to design and characterize a multislotted surface-mounted permanent magnet (SPM) motor. The SPM motor has been widely used for automobile, industry automation, etc., since it offers high power density and torque. In general, the design of the SPM has multislots on iron-core, and it is essential to accurately analyze the change in the magnetic field caused by slotting effect. The existing analytical models, such as relative permeance (RP), complex relative permeance (CRP), and subdomain (SD), have some limitations, relatively low accuracy and long computational time, which are crucial as the design of the multislotted SPM is complicated. The proposed model in this article utilizes the exact complex relative permeance (eCRP) of each slot pattern and synthesizes the eCRPs (Syn-eCRP) by the superposition principle so that it reduces the computation time for multislotted design with high accuracy. Furthermore, the analysis can be explored for a number of various design parameters of the SPM motor, such as the size of motor components, pole-slot combination, the number of slots, internal/external rotor, and radial/parallel magnetization. This model is validated through a comparison of relative permeance, magnetic fields, and cogging torque with the finite element method and experiment of motors. In total, two core designs, single-notch and double-notch designs that have two and three slot patterns, are demonstrated for the effectiveness and accuracy. The results show that the Syn-eCRP can be utilized to design and analyze the SPM motor with high accuracy and fast computation simultaneously.