A Novel Mathematic Model of Doubly Fed Brushless Machine

Due to the different pole numbers of power winding and control winding, the rotating speeds of magnetic fields generated by the two winding currents of the doubly fed brushless machine (DFBM) are different. Different rotating reference frames are usually needed to analyze the performance of the DFBM. In order to simplify the complicacy of the mathematic model and to implement easily vector control, a new model of DFBM based on the slip frequency rotating equivalent control winding is proposed in this paper. By taking the equivalence that the rotating magnetic field generated by the stationary stator control winding can be produced by an equivalent rotating winding with the slip frequency rotating speed like the rotor winding of a wound rotor induction machine. The new model of DFBM can be used for performance analysis and vector control in the same way as that of the conventional wound rotor induction machine.