Electromagnetic performance of non-overlapping stator wound field synchronous machine with salient pole rotor

Stator wound field synchronous (SWFS) machine has the advantages of low material cost and easy thermal management. For the SWFS machines, the non-overlapping windings can be employed to reduce the copper usages and manufacture costs. In [1], a segmental-rotor non-overlapping SWFS (SNSWFS) machine is proposed, Fig.1(a). However, the segmental rotor is not robust and not easy for fabrication. Besides, the torque density of the SNSWFS machine is relatively low since the rotor segments restrict the flux paths. In order to overcome these drawbacks, conventional salient pole rotor can be employed. In [2], the segmental rotor of the SNSWFS machine is replaced by conventional salient-pole rotor without changing the field coil polarities, which results in a non-overlapping SWFS machine having alternate field coil polarities (NSWFS-AP), and consequently high flux leakage, Fig.1(b). Therefore, the torque density of the NSWFS-AP machine is even much lower than that of the SNSWFS machine of the same size, Fig.1(d) (8-pole and 5-pole machines show the highest torque densities among 12-slot SNSWFS and 12-slot NSWFS-AP machines, respectively).