Comparison of Tolerance Sensitivities of the Open-Circuit Airgap Flux between Spoke-type and Surface-Mounted Permanent Magnet Motors Considering Manufacturing Tolerances

Abstract

This paper compares tolerance sensitivities of the open-circuit airgap flux (OCAF) between a surface-mounted permanent magnet (SPM) and a spoke-type PM motors according to variations of the airgap lengths and presents their naturally different tolerance sensitivities using the magnetic equivalent circuit (MEC) and finite element method (FEM). First, the MECs of the motors are modeled considering the additional airgap between PMs and rotor core and the OCAF equations of the motors are derived from the MECs to analyze the effects of design variables on the OCAF, respectively. Second, tolerance sensitivity of each motor is carried out using the partial derivative method to directly compare the natural-born characteristics of the OCAF of the two motors. Finally, the results are validated using the FEM considering the variations of the airgap lengths.