Spoke-type PM Vernier as a Promising Candidate for MW-Scale Direct Drive Wind Turbine Applications

This paper presents the design and analysis of an outer rotor spoke-type PM vernier (ST-PMV) generator as a potential candidate for MW-scale direct drive (DD) wind turbine applications. ST-PMV despite of its magnetic potential oscillations issue still has certain advantages over the general surface PM vernier machine especially in terms of the power factor. At power ratings of MW-Scale, there are serious concerns of having worse power factor, magnetic saturation of cores and PM demagnetization issues. In this regard, in order to obtain the optimum performance, various design aspects are discussed such as the proper selection of the PM dimensions that is interlinked with the choice of slot geometry, specific electric loading and the slot-pole combination. For the proper selection of the various entailed design parameters of ST-PMV a design criteria based on certain design assumptions is developed. Moreover, it is pointed that for the proper sizing of the core parts it is important to accurately consider the magnetic potential oscillations issue. Finally, by using the developed design procedure five 15-MW ST-PMV generators are designed and their electromagnetic performances are comparatively analyzed against a 15-MW conventional DD PM generator.