Influence of Thermal Expansion on Eccentricity and Critical Speed in Dry Submersible Induction Motors

Lv, Qiang; Bao, Xiaohua; He, Yigang

doi:10.5370/jeet.2014.9.1.106

Cited by 4 publications

(2 citation statements)

References 18 publications

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“…Coupling vibration between rotating machinery and electromagnetic field is worth exploring. Meanwhile, the rotating structure is affected by the temperature field and surrounding acoustic excitation [178]. Due to the flexibility of structure, the multiphysics interaction will produce significant effects on the dynamic properties of structures.…”

Section: Multiphysics Coupled Modelingmentioning

confidence: 99%

Review of Electromagnetic Vibration in Electrical Machines

Han

Chu

2018

Energies

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Electrical machines are important devices that convert electric energy into mechanical work and are widely used in industry and people's life. Undesired vibrations are harmful to their safe operation. Reviews from the viewpoint of fault diagnosis have been conducted, while summaries from the perspective of dynamics is rare. This review provides systematic research outlines of this field, which can help a majority of scholars grasp the ongoing progress and conduct further investigations. This review mainly generalizes publications in the past decades about the dynamics and vibration of electrical machines. First the sources of electromagnetic vibration in electrical machines are presented, which include mechanical and electromagnetic factors. Different types of air gap eccentricity are introduced and modeled. The analytical methods and numerical methods for calculating the electromagnetic force are summarized and explained in detail. The exact subdomain analysis, magnetic equivalent circuit, Maxwell stress tensor, winding function approach, conformal mapping method, virtual work principle and finite element analysis are presented. The effects of magnetic saturation, slot and pole combination and load are discussed. Then typical characteristics of electromagnetic vibration are illustrated. Finally, the experimental studies are summarized and the authors give their thoughts about the research trends.Energies 2018, 11, 1779 2 of 33 vibration mechanism can be helpful for the design of electrical machines. Therefore, the study of the electromagnetic vibration of electrical machines has practical significance.Electromagnetic vibrations are usually generated by the distorted air-gap field of an eccentric rotor in electrical machines. The uneven air-gap is directly related to the eccentricity, which is common in rotating electrical machines. Eccentricity can be caused by several reasons, such as relative misalignment of the rotor and stator in the fixing stage, misalignment of the load axis and rotor shaft, elliptical stator inner cross section, wrong placement or rubbing of ball bearings, mechanical resonance, and unbalanced loads [1,2]. Eccentricities can be further subdivided into two categories: circumferential unequal air gaps and axial unequal air gaps. The former can be grouped into static eccentricity and dynamic eccentricity. In the case of static eccentricity, the rotor rotates around its own geometric axis, which is not the geometric axis of the stator. In the case of dynamic eccentricity, the rotor is not concentric and rotates around the geometric axis of the stator. In reality, both static eccentricity and dynamic eccentricity tend to coexist. An inherent static eccentricity exists, even in newly manufactured machines, due to the build-up of tolerances during the manufacturing and assembly procedure, as has been reported in [3]. Unequal air gaps cause unbalanced magnetic forces (UMFs) [4] on the rotor, which lead to mechanical stress on some part of the shaft and bearing. After prolonged operation, these fac...

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Section: Multiphysics Coupled Modelingmentioning

confidence: 99%

Review of Electromagnetic Vibration in Electrical Machines

Han

Chu

2018

Energies

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“…The rotation speed at which resonance occurs is called resonance speed or critical speed [5]. Factors such as manufacturing errors, assembly errors, temperature change, pre-tightening force, and so on all affect the resonance speed of the rotor [6][7][8][9]. If the spindle is operated at or near the resonance speed, it will cause severe lateral bending vibration, which not only degrades the finish surface quality, but will even cause damage to the spindle [10].…”

Section: Introductionmentioning

confidence: 99%

Resonance speed measurement of high-speed spindle using an instruction-domain-based approach

Gao

Cao

et al. 2019

Meas. Sci. Technol.

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Although the manufacturing and assembling technology of the machine tool has become more and more mature, eccentricity of the spindle is still unavoidable and is an important source of spindle vibration. When the spindle rotation frequency is close or equal to the natural frequency of the spindle structure, spindle vibration will increase sharply, causing resonance (resonance speed). The high-speed spindle is more prone to cause resonance speed due to its wide speed range and large amount of centrifugal force. Machining at the resonance speed not only degrades the surface quality but also accelerates the degradation of the spindle performance. Aiming at this problem, this paper presents a G instruction-domain-based resonance speed measurement method. This method realizes the measurement by performing the spindle acceleration signal analysis in the instruction domain, which overcomes the shortcomings of the hammer impact test-based method (complicated operation), it is suitable for in situ application. The effectiveness of the proposed method was verified by hammering modal test and motor vibration test. The influence of resonance speed on the milling surface quality and the influence of different tools on the resonance speed was explored. Based on the proposed method, a portable spindle resonance speed measurement tool and a CNC system resonance speed avoidance module were developed.

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