Electromagnetic Performance Comparison between 12- Phase Switched Flux and Surface-Mounted PM Machines for Direct-Drive Wind Power Generation

In this paper, the 12-phase switched flux (SF) permanent magnet (PM) (SFPM) machine and two surface-mounted PM (SPM) machines designed for direct-drive wind power generation are comparatively analyzed. Firstly, feasible stator-slot/rotor-pole combinations for symmetrical 12-phase winding layout are investigated for both machine topologies. Secondly, the key design parameters of the PM generators are optimized by finite element (FE) analysis. Thirdly, electromagnetic performances including air-gap field, cogging torque, static torque, inductance, output voltage and its regulation factor, output power and efficiency of the generators are compared. A 10 kW 24-slot/22-pole SFPM prototype is built and tested to validate the FE predicted results.