Modeling and effects of in-situ magnetization of isotropic ferrite magnet motors

This paper outlines a method using finite element analysis to model the magnetization process of a small brushless surface-magnet 3-phase motor with isotropic ferrite magnets and concentrated windings. This is aimed at allowing in-situ magnetization using the 3-phase machine winding. Radial magnetization is the nominal manufactured magnetization pattern; however, the in-situ method leads to a variation in the magnetization pattern and the performance is examined using open-circuit simulations. The properties of the magnet material (a ferrite 5 type) are examined in order to simulate the magnetization. Bulk magnetization H_s-sat levels for ferrite type 5 indicate a 10 kOe; however, in this paper localized magnetization is examined using finite element analysis. The use of magnetization functions allows the magnetization pattern to be applied to the simulations. This paper uses a standard manufactured machine to carry these out. Open circuit experiments are conducted to validate the presented method.