Comparative Analysis of Brushless Doubly-Fed Machines with Different Rotor Structures

Brushless doubly fed machine (BDFM) has different rotors, i.e. salient-pole, multilayer flux barrier, short-circuit winding. However, there is no comparative analysis on the performances of the different rotor types. So, this paper studies their differences from both the analytical equations and finite element analysis (FEA). First, the basic structure and working principle of BDFMs are introduced. Subsequently, under the same stator core and armature winding, the excitation magnetomotive force (MMF), airgap flux density, and torque of the three rotors are analytically derived and compared. Finally, based on FEA, the key performances including rated torque, power factor, overload torque, total harmonic distortion (THD) of line back-EMF, short-circuit current, etc. are compared and analyzed.