Finite element analysis of brushless DC motors for flux weakening operation

Finite element analysis is used to obtain the non-linear variation of axis and cross-axis flux-linkages for a dq model of an interior magnet, brush-less DC motor (BLDC). The model is used to compare competing designs of the conventional form of BLDC with designs of a novel type that has q-axis flux barriers. It is shown that the flux-barrier motor will give (i) equal rated performance, and (ii) better over-rating performance.