Investigation of Inner/Outer rotor permanent magnet flux switching generator for wind turbine applications

Abstract

In this paper two permanent magnet flux switching generator (PMFSG) is designed for 2 kW output power and 220 V phase voltage at 1500 rpm and comparatively analyzed for wind turbine applications. Both PMFSG share same C-core stator connected back-to-back through flux bridge (β) with different rotor position i.e., inner rotor PMFSG (IR-PMFSG) and outer rotor PMFSG (OR-PMFSG). A detailed comparative analysis with various β for both IR-PMFSG and OR-PMFSG are performed under static characteristics, rated condition, overload capability and over-speed capability for generating output voltage, current, power and efficiency. Comparison of the static characteristics reveal that IR-PMFSG offers 47.93% higher rated power, 2.83% higher efficiency, 22.78% more magnetic flux, 56.91% reduced cogging torque and 83.18% lower torque ripples at the cost of 62.69% higher voltage regulation factor. Furthermore, under rated operating condition and overload capability with same specifications it is found that IR-PMFSG exhibits 1.47 times power than that of OR-PMFSG counterpart. Finally, over-speed capability is investigated in term of the output power which shows that IR-PMFSG significantly generate almost 2.25 time of the specification power whereas OR-PMFSG exhibits nearly 1.25 times power. This analysis shows that IR-PMFSG can be operated at wide-speed rage for higher power specification requirements maintaining efficiency greater than 90%.