Effects of Structure Shape Optimizing Techniques on the Performance of a Large Scale Wound Rotor Synchronous Machine

Abstract

Wound rotor synchronous machines with fractional slot non overlapping windings are attractive for low speed, grid connected wind applications. As they contain no magnets and provide ample flux variation, with the added advantages of the fractional slot non overlapping winding they are a very cost effective solution for this kind of application. The main drawback of this kind of winding is high harmonic content in the air gap magneto-motive force waveform, which is evident by the presence of high torque ripples and increased rotor core losses leading to a depreciated overall machine performance. This paper seeks to study the effects of pole placed flux barriers and pole shaping techniques on the performance characteristics of a large scale wound rotor synchronous machine. To perform such a task, a 3MW, 400V, 16 pole, 18 slots, double layer wound rotor synchronous machine is designed and analyzed using a python based in-house static, 2D time stepped finite element method called SEMFEM and verified in the commercial transient finite element method software Ansys Maxwell.