Rotor Unbalanced Magnetic Pull Characteristics Properties in Synchronous Generators Due to Dynamic Air-gap Eccentricity Faults

The article deals with the optimal control of the positional electric drive of the stator element of a segment-type wind turbine. The calculation options charts current in the assumption of the minimum energy consumption and the implementation of line chart current using the phenomenon of capacitor discharge. The analysis of the implementation is expressed in a jump-like change in current and a triangular graph of the speed change. This article deals with small capacity synchronous wind turbine generators with a segment type stator. These units have the possibility of intentionally changing the air gap between the rotor and stator. This allows: (1) Reduce the starting torque on the rotor shaft, which will allow the rotor to pick up at low wind speeds. (2) Equivalent to change of air gap in this case is change of excitation of synchronous generators. Thus, the purpose of the article is to consider a method of excitation of generators in a segmented design, by controlling the gap with the electric drive, while providing control should be carried out with minimal losses.

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Direct-Drive Synchronous Generators with Excitation from Strontium-Ferrite Magnets: Efficiency Improvement

Latvian Journal of Physics and Technical Sciences ◽

10.2478/v10047-012-0018-0 ◽

2012 ◽

Vol 49 (4) ◽

pp. 3-13

Author(s):

A. Serebryakov ◽

N. Levin ◽

A. Sokolov

Keyword(s):

Permanent Magnets ◽

Strontium Ferrite ◽

Air Gap ◽

Electric Machine ◽

Specific Power ◽

Hard Material ◽

Efficiency Improvement ◽

Direct Drive ◽

Synchronous Generators ◽

Starting Torque

Direct-Drive Synchronous Generators with Excitation from Strontium-Ferrite Magnets: Efficiency Improvement The authors consider the possibility to raise the specific power of synchronous generators with excitation from inexpensive permanent magnets. For this purpose, it is proposed to use tooth-wise windings and permanent magnets based on inexpensive magneto-hard material, e.g. strontium-ferrite. The magnets are to be placed between the rotor teeth, the alternate polarity of which is facing the air-gap. This provides a simpler and cheaper technology of making such a generator and improves its reliability. The proposed rational bevelling of the stator teeth not only raises the specific power of the generator but also reduces the level of noise and vibrations, extends the longevity of the magnets and bearings as well as facilitates the starting torque of the electric machine, e.g. if it is employed as wind generator.

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Analysis of Unbalanced Magnetic Pull Calculation in Generators With Two Pole Pairs

Volume 1: 22nd Biennial Conference on Mechanical Vibration and Noise, Parts A and B ◽

10.1115/detc2009-87194 ◽

2009 ◽

Cited By ~ 1

Author(s):

Lucia Frosini ◽

Paolo Pennacchi ◽

Carlo Maria Stoisser

Keyword(s):

Time Instant ◽

Harmonic Spectrum ◽

Dynamical Behaviour ◽

Air Gap ◽

Dynamic Effects ◽

Accurate Calculation ◽

Unbalanced Magnetic Pull ◽

Turbo Generator ◽

Vibratory Analysis ◽

Linear Effects

The modelling of the unbalanced magnetic pull (UMP) and the analysis of its effects on the dynamical behaviour of a large turbo-generator are presented in this paper. The UMP is the consequence of the electromagnetic forces acting upon rotor and stator generator surfaces and depends on the non-uniform air-gap distribution between rotor and stator. The flexibility and the dynamic effects on the generator behaviour are taken into account by an accurate calculation of the air-gap distribution depending on the position in a generic time instant of the rotor inside the stator. The method is then applied for the vibratory analysis of a two pole pair generator of a steam turbo-set: the harmonic spectrum of the UMP is evaluated and the presence of non-linear effects highlighted.

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Study on the Unbalanced Fault Dynamic Characteristics of Eccentric Motorized Spindle considering the Effect of Magnetic Pull

Shock and Vibration ◽

10.1155/2021/5536853 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Zhan Wang ◽

Wenzhi He ◽

Siyuan Du ◽

Zhe Yuan

Keyword(s):

Dynamic Model ◽

High Speed ◽

Air Gap ◽

Fault Analysis ◽

Experimental Results ◽

Machining Accuracy ◽

Motorized Spindle ◽

Unbalanced Magnetic Pull ◽

Static Eccentricity ◽

Simulation Results

Unbalanced fault is the most common fault of high-speed motorized spindle, which is the main factor affecting the machining accuracy of high-speed spindle. Due to the unbalanced magnetic pull produced by the air gap eccentricity of the stator and rotor, the unbalanced vibration of the motorized spindle will be further aggravated. In order to explore the dynamic behavior and motion law of the unbalanced fault motorized spindle under the eccentric state, a dynamic model of the unbalanced fault of the high-speed motorized spindle considering the unbalanced magnetic pull was established. Taking the eccentric motorized spindle customized by the research group as the research object, the dynamic model is established, simulated, and analyzed, and the response change law of motorized spindle under the effect of different speed, unbalance, and air gap is obtained. The simulation results show that the unbalanced magnetic pull caused by static eccentricity will increase the unbalanced vibration of motorized spindle, and the unbalanced vibration will also increase with the increase of static eccentricity. The vibration caused by unbalanced magnetic pull does not increase with the increase of rotating speed. In frequency-domain analysis, when there is unbalanced magnetic pull, the peak appears at 0 Hz, and the amplitude of fundamental frequency vibration will increase with the increase of eccentricity. The experimental results show that the greater the eccentricity is, the greater the unbalance vibration of the motorized spindle is. The experimental results are consistent with the simulation results, which further verify the accuracy of the model. The research results lay a theoretical basis for fault analysis and diagnosis of coupling fault motorized spindle.

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