Influence of rotor topologies and cogging torque minimization techniques on axial-flux permanent magnet machine under static eccentricities

In this paper, axial-flux permanent magnet machine is modelled to precisely imitate static eccentricities. From the model, the effect of the non-uniform airgap permeance which arises from static eccentricities on current harmonics and torque is experimentally studied. The influence of two cogging torque minimization techniques on both signatures, in the presence of static eccentricity is also examined and a comparison is made between the single-sided and double-sided rotor topologies. Static eccentricity incited significant increases in the amplitudes of space and sub-harmonics in the single-sided topology. The double-sided topology, unlike the single-sided topology, is found to be tolerant to the presence of static eccentricity due to opposing effect of the resulting asymmetrical properties of the airgap. Also, the cogging torque minimization techniques do not impair on the fault detection technique.