Finite element analysis of an anisotropic ferrite bonded magnet for BLDC motor design

In many cases, ferrite bonded magnets used in inner-rotor type small brushless DC (BLDC) motors do not have rotor core, and the magnetization directions of permanent magnets do not have only parallel or radial direction. In this paper, the magnetization directions of a ferrite bonded magnet are analyzed by finite element analysis for magnetization procedure. The characteristics of an inner-rotor type BLDC motor are analyzed by using the analyzed magnetization model. In the analysis, the overhang effect of the magnet is calculated by using 3-D FEM. The validity of the analysis method is verified by comparing the analyzed results with measured ones.