Eccentricity is an inevitable fault in electric motors and hence its diagnosis is an important topic. Thus, the influence of static and dynamic eccentricities on the harmonics of the frequency spectra of the unbalanced magnetic pull is analyzed. In this article, dimensional tolerances of the rotor and the stator are also considered. All parts have dimensional tolerances in their designs and their real magnitudes vary to some extent from the theoretical values after the manufacturing process. Thanks to analytical calculations and finite element simulations, verified with experimental results, it is observed 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 unbalanced magnetic pull. 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. Finally, after decoupling the effect of tolerances and eccentricities, the frequency harmonics that are indicators of rotor tolerances are determined, and a new methodology based on ratios of amplitudes of adjacent harmonics is proposed to identify eccentricities.

Permanent Magnet Synchronous Motors (PMSMs) are increasingly being used and are required to satisfy noise and vibration specifications. Thus, it is necessary to develop design guidelines for electric motors that consider vibration response as a key output of the design. This work shows the influence of the main design parameters regarding PMSMs: the number of slots and the number of poles. First, the influence of the number of slots in the natural frequencies is analysed by Finite Element calculations, which are experimentally verified. Then, the analytical calculation of the vibration response is explained. This is applied for several combinations of the number of slots and the number of poles, and the results are compared. Considering the analytical development, a procedure to choose the most adequate combination of the number of slots and poles is proposed. The analytical predictions are validated according to experimental measurements in two machines.

There are several fault types that may arise in electric motors decreasing both reliability and comfort. Eccentricity is one of the main faults, and therefore, tools are needed to detect the motors that do not fulfil the quality requirements. This paper proposes a methodology based on a novel experimental test bench to assess both static and dynamic eccentricities, since it generates continuous and controlled values of both types of eccentricities. A permanent magnet synchronous motor is analysed in the test bench. The unbalanced magnetic pull is measured by a force transducer located below the stator and the electromagnetic field in the air gap is determined by search coils embedded around the teeth of the stator. The experimental results show the capability of these two variables to detect the presence of eccentricities, and determine its type (static or dynamic) and level.

Eccentricity is an inevitable fault in electric motors and hence its diagnosis is an important topic. Thus, the influence of static and dynamic eccentricities on the harmonics of the frequency spectra of the unbalanced magnetic pull is analyzed.In this study, dimensional tolerances of the rotor and the stator are also considered. All parts have dimensional tolerances in their designs and their real magnitudes vary to some extent from the theoretical values after the manufacturing process. Thanks to the finite element simulations, verified with experimental results, it is observed 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 unbalanced magnetic pull. 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.

The use of electric motors, and particularly, Permanent Magnet Synchronous Motors, is increasing in recent years, and their vibration response is one of the most crucial aspects regarding their behaviour. Thus, the reduction in vibrations is one of the key objectives when optimizing electric motors. In an initial design state, the influence of the main design parameters on the behaviour of the machines is not always clear. For that reason, this work presents a global sensitivity analysis procedure that allows identifying the most influential design parameters and determining guidelines to optimize the design of Permanent Magnet Synchronous Motors. First, the analytical calculations employed to estimate the electromagnetic torque and the vibration response of the machine are described. Then, the sensitivity analysis procedure, based on the Monte Carlo method, is presented, and the conditions to apply the method successfully and accurately are analysed. Finally, the sensitivity analysis is performed for a particular electric motor design, and some general design guidelines are deduced, which can be extrapolated to similar machines.