Minimization of Cogging Torque in Axial Field Flux Switching Machine Using Arc Shaped Triangular Magnets

Abstract

Axial flux permanent magnet machine (AFPMM) provides high torque characteristics at low speeds without any mechanical gears. AFPMMs have numerous applications in wind energy, electric cars, and direct drive elevator applications. These machines have low cost and improved power to weight ratio. However, single sided AFPM suffers from torque ripples because of its non-sinusoidal back emf, cogging torque, and rotor eccentricity. There are two major components of pulsating torque, namely torque ripples and cogging torque. In PM machine design, the cogging torque is a serious concern because it adds unwanted harmonics to the pulsating torque. Whereas the torque ripples cause noise and vibrations. In order to gain high efficiency, torque ripples should be minimum. The aim of this research is to design 'Slotted axial field flux switching permanent magnet machine'. Mathematical models are used to design the machine and Finite element method (FEM) has been used to analyze the machine. In addition, Latin hypercube sampling (LHS) has been used to create the samples. Finally, Kriging Method is used for approximating the model and genetic algorithm has been applied to get the optimum machine. The results showed 61.8 % reduction of the cogging torque in the proposed machine model as compared to the conventional one. Moreover, the optimized model further provided 6.15 % reduction in the cogging torque as compared to the proposed one.