Design and fabrication of an outer rotor permanent magnet synchronous generator with fractional winding for micro-wind turbines

Permanent magnet synchronous generators (PMSGs) have been widely used in micro-wind turbines (MWTs) for direct-drive applications. The generating maximum power from the PMSGs used in the MWTs is desired. However, cogging torque (CT) and design form of the PMSGs prevent this. Therefore, various methods are applied to reduce the CT of PMSGs in the literature. Some of them are inapplicable and some are the ones that cause power loss. In this study, to overcome the expressed causes, a new design, fabrication, and application of an outer rotor PMSG with fractional winding having a slot-pole combination technique for MWTs have been suggested, designed, and implemented on an MWT. As a result of the new design combination of +/- 1 or +/- 2 between the numbers of stator slot (N-S) and the number of pole-pairs (2p), the ratio of the CT value to the nominal torque value in the new prototyped outer rotor PMSG was found as 6.25%. Finally, the operating power can generate 1029 W through the prototype PMSG with fractional winding having a slot-pole combination technique integrated into the direct-drive MWT system.