Influence of Rotor Topologies and Cogging Torque Minimization Techniques in the Detection of Static Eccentricities in Axial-Flux Permanent-Magnet Machine

In this paper, the effect of static eccentricity on current harmonics and torque ripple in an axial-flux permanent-magnet machine with fractional-slot concentrated winding is investigated. Cogging torque minimization techniques are also explored in the presence of the anomaly to better understand their sensitivity to the condition. Also, the impact of single-sided and double-sided rotor topologies on both current harmonics and torque ripple is examined. It is found that static eccentricities incite significant increases in the amplitudes of space and subharmonics in the single-sided topology, which may be mitigated by the cogging torque minimization techniques. The double-sided topology is tolerant to the presence of static eccentricities unlike the single-sided topology; this is due to the opposing effect of the resulting asymmetrical properties of the air gap. Finally, this paper establishes a detection technique for static eccentricities in single-sided axial-flux permanent-magnet machine whereby the cogging torque minimization techniques do not impair on them.