Effect Of Static Eccentricity Research Articles

Effects of static eccentricity on the no‐load back electromotive force of external rotor permanent magnet brushless DC motor used as in‐wheel motor

The no-load radial magnetic field and no-load back electromotive force (EMF) of external rotor permanent magnet brushless DC motor (PMBLDCM) are calculated by applying the correction coefficient of magnetic conductance here, taking into account the stator slotting and static eccentricity effects. An external rotor PMBLDCM with 51-slot/46-pole, used as in-wheel motor, is taken as an example, the analytical calculation results of the no-load back EMF are validated by the finite-element method and experiment. The influences of static eccentricity ratio on the no-load radial magnetic field and no-load back EMF are investigated based on the analytical model. The investigation shows that static eccentricity does not change the harmonic contents of no-load radial magnetic field, so it does not change the harmonic contents of three-phase no-load back EMFs. However, static eccentricity changes the space order of no-load radial magnetic field, resulting in the different total harmonic distortions of three-phase no-load back EMFs; in other words, the asymmetric distortions of three-phase no-load back EMFs are generated. The asymmetric distortions of three-phase no-load back EMFs are intensified with the increase in static eccentricity ratio.

Analytical Technique for Analysis and Detection of Eccentricity Fault in Surface-Mounted Permanent Magnet Generators Using No-Load Voltage Signature

This paper presents a method for modeling the effects of static eccentricity, dynamic eccentricity, and mixed eccentricity faults on the electromotive force (emf) of the surface-mounted permanent magnet generators (SMPMGs). The model is based on the combination of conformal mapping method (complex relative permeance) and eccentricity relative air gap permeance and it presents explicit formulas for no-load magnetic field distribution, magnetic flux, and emf in SMPMGs under different eccentricity fault types, some have not been so far considered elsewhere. The analytical and also numerical results show that there are some side-band components in the emf signature which can be used as eccentricity fault index. Analytical results validate by time-stepping finite element method (TSFEM) results.

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.