In the paper, the structure, operation principles and flux weakening control methods for the stator doubly-fed doubly salient (SDFDS) motor are introduced.

This new type of brushless double-feed machines rotor is designed by pole-changing method.

The paper introduces the structure of BDFM and the principle of its speed control. The superiority of BDFM driving for fan-type load is discussed base on the analysis on its power relationship.