Calculation and measurement of unbalanced magnetic pull in cage induction motors with eccentric rotors. Part 1: Analytical model

Smith, Alexander C.; Dorrell, David G.

doi:10.1049/ip-epa:19960155

Cited by 163 publications

(67 citation statements)

References 11 publications

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“…The magnetic spring constant c m has a negative reaction, which is shown in Dorrell [7], Smith and Dorrell [8], Schuisky [9], Holopainen [10], Arkkio et al [11], Belmans et al [12], Stoll [13], and Werner [14,15]. This means that a radial movement between the rotor and stator creates an electromagnetic force that tries to magnify the movement.…”

Section: Rotordynamic Modelmentioning

confidence: 99%

“…Dynamic eccentricity is caused if the rotor is bent or if the rotor core is eccentrically positioned on the rotor shaft due to, for example, tolerances in the punching process of the rotor sheets. In this case a rotating magnetic force occurs, which is called UMP (unbalanced magnetic pull), which has been investigated in many publications as in Dorrell [7], Smith and Dorrell [8], Schuisky [9], Holopainen [10], Arkkio et al [11], Belmans et al [12], Stoll [13], and Werner [14,15].…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Vibration Analysis Regarding Excitation due to Elliptical Shaft Journals in Sleeve Bearings of Electrical Motors

Werner

2012

International Journal of Rotating Machinery

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This paper shows a theoretical vibration analysis regarding excitation due to elliptical shaft journals in sleeve bearings of electrical motors, based on a simplified rotordynamic model. It is shown that elliptical shaft journals lead to kinematic constraints regarding the movement of the shaft journals on the oil film of the sleeve bearings and therefore to an excitation of the rotordynamic system. The solution of the linear differential equation system leads to the mathematical description of the movement of the rotor mass, the shaft journals, and the sleeve bearing housings. Additionally the relative movements between the shaft journals and the bearing housings are deduced, as well as the bearing housing vibration velocities. The presented simplified rotordynamic model can also be applied to rotating machines, other than electrical machines. In this case, only the electromagnetic spring value c m has to be put to zero.

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Section: Rotordynamic Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical Vibration Analysis Regarding Excitation due to Elliptical Shaft Journals in Sleeve Bearings of Electrical Motors

Werner

2012

International Journal of Rotating Machinery

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“…However, most of the literature focuses on an eccentric cage induction machine and the forces and vibrations related to it. The unbalanced magnetic pull due to rotor eccentricity has also been a topic of investigation in the past [4][5][6]. The analytical models have been validated by experimental investigations.…”

Section: Introductionmentioning

confidence: 99%

Influence of the rotor eccentricity on the torque of a cage induction machine

Silwal¹,

Rasilo

Belahcen³

et al. 2017

Archives of Electrical Engineering

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Abstract:The non-uniform air gap in an electrical machine caused by rotor eccentricity creates an asymmetrical flux-density distribution in the air gap. This can affect the nominal torque produced by the machine. Eccentricity also produces forces that act on the rotor which may also have an effect on the torque. Thus, it is important to know how the torque of the machine behaves. In this paper, the torque of a cage induction machine is studied when the machine has dynamic eccentricity. The study is performed using the finite element method and a magnetic vector potential formulation. The torque is calculated by the method of energy balance. The harmonic components of the torque are also analyzed. The results show that the machine under eccentricity does not exhibit the same torque as a normal healthy machine. The harmonic components around the first principal slot harmonic is most affected.

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“…Lots of studies are by means of analytical method which is relied on an accurate result of the magnetic field. For example, Smith et al described a method for predicting the static and pulsating unbalanced magnetic pull (UMP) in a three-phase, induction motor with an eccentric rotor [7,8]. Guo et al [9] obtained an analytical expression of electromagnetic forces by expressing the air gap permeance as a Fourier series, but these methods are suitable for the initial design and optimization.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Finite Element Analysis to Investigate the Vibration of Oblique-Stud Stator Frame in a Large Hydropower Generator Unit

Zhou

Peng

et al. 2017

Energies

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This paper presents an investigation on the undesirable vibration of an oblique-stud stator frame in a large hydropower generator by means of experimental and finite element (FE) analysis. First, field experimental tests were performed, and the results indicate that the main vibration component comes from electromagnetic factors. Then, a 2D-magnetic and 3D-mechanical FE model was developed to investigate the vibration of the stator frame under the action of electromagnetic forces. A set of contrast models was established to study the effects of different kinds of eccentricity and different structures. Based on the comparative analysis between the results of simulations and experimental tests, it can be inferred that the abnormal vibration is generated because of the lack of stiffness in the upper part of structure and the existence of dynamic eccentricity in the rotor-stator system. In addition, the structural simulation analysis shows that the flexible designed oblique-stud stator frame is relatively vulnerable against the electromagnetic forces.

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Calculation and measurement of unbalanced magnetic pull in cage induction motors with eccentric rotors. Part 1: Analytical model

Cited by 163 publications

References 11 publications

Theoretical Vibration Analysis Regarding Excitation due to Elliptical Shaft Journals in Sleeve Bearings of Electrical Motors

Theoretical Vibration Analysis Regarding Excitation due to Elliptical Shaft Journals in Sleeve Bearings of Electrical Motors

Influence of the rotor eccentricity on the torque of a cage induction machine

Experimental and Finite Element Analysis to Investigate the Vibration of Oblique-Stud Stator Frame in a Large Hydropower Generator Unit

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