Demagnetization analysis of outer-rotor-type BLDC motors considering permanent magnet overhang structure

Abstract

This paper presents an analysis of demagnetization of an outer rotor type brushless DC (BLDC) motor with a permanent magnet (PM) overhang structure. The proposed model converts the operating points of PM to consider such a three-dimensional (3D) structure in two dimensions (2D). In addition, the rotor yoke thickness of the proposed model is increased to consider the housing rotor. Ferrite PMs require demagnetization analysis owing to their decreasing coercivity at lower temperatures compared with rare-earth PMs. Hence, demagnetization analysis is conducted using a proposed model while considering, the PM overhang structure. The demagnetization analysis results are compared with the results of proposed model and 3D FEA analyses.