MW-Class Stator Wound Field Flux-Switching Motor for Semidirect Drive Wind Power Generation System

Stator wound field flux-switching (SWFFS) motors with all excitation sources placed on a stator are suitable for wind power generation systems (WPGSs) because of their simple and robust structure, nonusage of rare-earth magnets, wide speed, controllable magnetic field, and easy heat dissipation. However, the claimed advantages of SWFFS motors have not been fully investigated based on megawatt (MW)-class WPGS. Hence, an SWFFS machine is designed and investigated for semidirect drive WPGS in this paper. First, the topology and operation principle of the SWFFS machine are investigated. Second, the air-gap flux density excited by the dc field and armature currents is analyzed separately based on the Fourier analysis method. Third, electromagnetic performances, including air-gap magnetic field, flux linkage, and electromagnetic torque, are calculated by using the theoretical field model and two-dimensional finite element analysis (FEA). Fourth, the output characteristics of the SWFFS generator, such as output voltage, output power, and efficiency, under different operating conditions are obtained. Finally, the analytical model and FEA results are validated through experiments based on an MW-class prototype.