Effect of rotor eccentricity on the magnetic field in the air-gap of a non-salient-pole machine

Swann, S.A.

doi:10.1049/piee.1963.0124

Cited by 26 publications

(5 citation statements)

References 2 publications

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“…Using similar approximation in his paper as early as in 1963, S.A. Swann [106] obtained flux density distribution in an eccentric-rotor machine which lay quite closely to the result of a rigorous method which included conformal transformation.…”

Section: Unbalanced Magnetic Pull and Machine Stiffnessmentioning

confidence: 70%

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Limits, Modeling and Design of High-Speed Permanent Magnet Machines

Borisavljevic¹

2013

Springer Theses

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Section: Unbalanced Magnetic Pull and Machine Stiffnessmentioning

confidence: 70%

“…To find relative permeance function conformal mapping is often used [106][107][108]. In [108] magnetic field which exists between two eccentric bodies representing rotor and stator of an electrical machine is determined.…”

Section: Unbalanced Magnetic Pull and Machine Stiffnessmentioning

confidence: 99%

Limits, Modeling and Design of High-Speed Permanent Magnet Machines

Borisavljevic¹

2013

Springer Theses

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“…22 " 24 Binns 25 has pointed out that, where permeance and m.m.f. harmonics of similar order are involved, the accuracy expected by the first approach is not high.…”

Section: Electromagnetic-force Wavesmentioning

confidence: 99%

“…. (22) where g r is the effective air-gap length in metres, approximately equal to 33 *'=£K(c 5 / )K(c r ,)=4-28 x 10 -4 (23)…”

Section: Calculation Of Sound-power Level From Force Wavesmentioning

confidence: 99%

Effects of rotor eccentricity on acoustic noise from induction machines

Ellison

Yang

1971

Proc. Inst. Electr. Eng. UK

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The variations of acoustic-noise power radiated from electric machines, having varying degrees of eccentricity of the rotor in the stator bore, were studied using a specially constructed rig in an anechoic chamber. A series of noise components, which were found in expsriments to vary considerably with rotor eccentricity, were identified analytically from the expressions for the mode numbers and frequencies of the magneticforce waves, taking into account the stator and rotor slotting, eccentricity and iron saturation. A method is presented for calculating the variation of important noise components with eccentricity. The effects on the noise power of different numbers of stator parallel paths and of different ways of connecting them were investigated using specially wound machines. Information is given concerning the choice of parallel paths and connections for noise reduction. List of principal symbolsA rd = amplitude of radial displacement, m a = outer radius of stator, m B = flux density, T b = halflength of the cylindrical part of machine, m c = speed of sound, m/s £" = modified Young's modulus, i.e. E/(l -y 2 ) N/m 2 , F = m.m.f., A / = frequency, Hz g = mean air-gap length, m g' = effective mean air-gap length, m h = parameter in sound power expression / = any integer J,(JC) = Bessel function of the first kind K,(x) = modified Bessel function k = order of m.m.f. space harmonic (Section 3.1) k = wave number, i.e. o»/c (Section 3.3) m = mode of vibration P = sound power, W p = number of pole pairs q -order of current time harmonic r 0 = radius of neutral layer, m r c = radius of stator core at the bottom of slot, m t = time, s Y/(x) = Bessel function of the second kind Z = number of slots z = axial distance (z -0 at centre of machine) a = angle of skew, rad 8 -logarithmic decrement e = relative eccentricity (infinitesimal quantity in eqn. 29) e' = effective relative eccentricity 6 = angle, rad A = permeance, Wb/A y -Poisson's ratio [Mo = permeability of free space, H/m p 0 = density of air, kg/m 3 a ra = radial force per unit area, N/m 2 = angular position, rad ifi -phase angle of m.m.f. wave co = angular frequency, rad/s Subscripts 1 supply c core dy dynamic ec eccentricity

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“…Researchers have given this kind of asymmetry a professional definition as air-gap eccentricity or rotor eccentricity [1][2]. Air-gap eccentricity widely exists in almost every generator and motor, and can be classified as three types [3][4][5], i.e., the static air-gap eccentricity (SAGE) whose minimum air-gap position is stable (such as the offset of the rotor), the dynamic airgap eccentricity whose minimum air-gap position will be changed as the rotor rotates (for example, the rotor is bending, or the rotor section is an ellipse), and the mixed air-gap eccentricity which is composed of the former two.…”

Section: Introductionmentioning

confidence: 99%

United Electromagnetic Characteristics and Online Monitoring Method of Static Air-gap Eccentricity of Turbo-Generator

Tang¹,

Ke²,

He³

et al. 2016

Journal of Electrical Engineering and Technology

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-The purpose of this paper is to investigate the united Electromagnetic characteristics for the effective monitoring on the static air-gap eccentricity (SAGE) of turbo-generator. Different from other studies, this paper not only studies on the unbalanced magnetic pull (UMP) and the vibration characteristics of the stator and the rotor, but also investigates the harmonic features of the magnetic flux density and the circulating current inside the parallel branches (CCPB). The theoretical calculation, together with the finite-element-method (FEM) simulation and the experiment verification, is taken for a SDF-9 type non-salient generator. It is shown that, when SAGE occurs, apparent doublefrequency UMP and vibrations will be produced both on the stator and the rotor, while the CCPB will have an obvious increment at the 1 st harmonic component. In addition, the amplitude of the magnetic flux density will be of cosine distribution in the circumferential position of the air-gap, while in normal condition it is a constant. Moreover, the pass-band amplitude, together with the 1 st harmonic of the magnetic flux density, will be enlarged as well. These united electromagnetic characteristics can be used as the diagnosis and monitoring criterion for SAGE.

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Effect of rotor eccentricity on the magnetic field in the air-gap of a non-salient-pole machine

Cited by 26 publications

References 2 publications

Limits, Modeling and Design of High-Speed Permanent Magnet Machines

Limits, Modeling and Design of High-Speed Permanent Magnet Machines

Effects of rotor eccentricity on acoustic noise from induction machines

United Electromagnetic Characteristics and Online Monitoring Method of Static Air-gap Eccentricity of Turbo-Generator

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