Design of a Brushless Doubly Fed Generator With Simplified Three-Phase Wound Rotor

Abstract

The brushless doubly fed generator (BDFG) shows great potential for the variable speed constant frequency ship shaft power generation applications due to its high reliability and low system costs. The rotor topology, which directly couples two stator magnetomotive forces (MMFs) with different pole pairs, is essential for the BDFG. However, existing rotor topologies cannot have both strong magnetic field coupling ability and simple structure. To address this problem, this paper proposes a simplified three-phase wound rotor that can produce two MMFs with different pole pairs simultaneously. Useless harmonics are also eliminated to achieve strong magnetic field coupling ability. The complete design method of a novel integral-slot single-layer winding acting as a basic unit of the compound wound rotor is presented. Two sets of basic winding units are merged into one according to the principle of Ampere-conductor wave, whose approaches are also thoroughly developed with the design example. The maximum number of winding layers and the coil types are reduced to simplify the winding layout. Steady-state performances of a prototype generator are analyzed by both finite element simulations and experimental tests, which verify proposed design methods and schemes.