Influence of Manufacturing Tolerances and Eccentricities on the Electromotive Force in Permanent Magnet Synchronous Motors

Abstract

Eccentricity is a common error in electric motors, so its diagnosis is an important issue. Therefore, the effect of static and dynamic eccentricities on the harmonics of the frequency spectra of the voltage of a phase is studied.In this research, dimensional tolerances of the stator and the rotor are also taken into account. The designs of all pieces have dimensional tolerances, hence their real magnitudes change to a degree from the theoretical values after the manufacturing process. As a result of the finite element simulations, validated by experimental results, the conclusion is that the deviations originated by the manufacturing tolerances produce changes in the amplitudes of some harmonics and also additional and characteristic harmonics in the frequency spectra of the phase voltage. These are not negligible and must be taken into account when robust eccentricity detection procedures are defined. Otherwise, harmonics originated by tolerances and by eccentricities can be misidentified.