Vibrations of induction machine excited by unbalanced magnetic pull caused by various rotor faults

Experimental analyses of squirrel-cage induction machine vibrations under several rotor fault conditions causing unbalanced magnetic pull are carried out in the paper. These fault conditions include dynamic eccentricity, different number of broken rotor bars and one case of fault combination. Frequency vibration spectra of faulty operational states are compared to the one of healthy machine

Design of synchronous machine

Tato diplomová práce je zaměřena na návrh turboalternátoru, tedy synchronního generátoru s hladkým rotorem. Hlavní část práce tvoří elektromagnetický návrh stroje. Na základě tohoto návrhu je pomocí 3D CAD softwaru vytvořen model stroje.Katedra elektromechaniky a výkonové elektronikyObhájenoThis master thesis is focused on design of turbine generator, which is synchronous machine with cylindrical rotor. Main part of thesis is concerned with electromagnetic design of the machine. On this base is created model of the machine by using 3D CAD software

Dynamické chování konstrukčních částí elektrických strojů

Disertační práce se zabývá problematikou vibrací statoru asynchronních strojů buzených magnetickými silami vznikajícími uvnitř stroje. V práci je uveden současný stav zkoumané problematiky včetně teoretického popisu rozložení magnetické indukce ve vzduchové mezeře stroje a jím danou velikostí magnetických sil působících na zuby statoru a rotoru. Dále jsou v práci analyzovány vybrané poruchy způsobující jednostranný magnetický tah, který ovlivňuje rozložení i spektrum vznikajících sil. V další části práce je definována metodika pro modelování vibrací statoru buzených magnetickými silami. Metodika je ověřena konečněprvkovou analýzou konkrétního stroje, kde jsou frekvenční spektra vypočtených magnetických sil působících na jednotlivé zuby statoru použita jako zdroje buzení vibrací stroje. Vibrace jsou analyzovány na samotném statorovém paketu, paketu uloženém v kostře a paketu v kostře upevněné na vertikálně uložený nosný rám a je vyhodnocen vliv jednotlivých konstrukčních částí na výsledné spektrum vibrací. Výsledky analýzy jsou porovnány s měřením na reálném stroji.NeobhájenoThe thesis deals with stator vibrations excited by the magnetic forces originating in the induction machines. It is referenced the current state of the examined issues including theoretical description of the flux density distribution along the air gap and resulting magnetic forces acting on the stator and rotor teeth. Further, the selected faults originating unbalanced magnetic pull which influences force distribution and spectrum are analyzed. A method for modelling stator vibrations excited by the magnetic forces is defined in the next part of the thesis. The method is verified by the finite element analysis of the specific machine. Frequency spectra of computed magnetic forces acting on the particular stator teeth are set as an excitation of the stator stack vibrations. Vibrations are analyzed on the models of stator stack, stator stack located in the stator frame and the stator assembly mounted to the vertical support. Influence of the particular structural parts on the resulting frequency spectra is evaluated. The results are compared to the measurement of the real machine

Diagnostics of static eccentricity in an induction machine using acoustic noise frequency spectra

The paper is focused on the experimental static eccentricity diagnostics using acoustic noise frequency spectra. The presented study presumes induction machine operating under constant load in an environment with steady acoustic noise producing facilities. The frequency spectra analyses are performed in a frequency range up to 1500 Hz allowing validation of the acoustic noise analyses by the vibration measurement

The determination of iron core loss characteristics of special electrical steel types

The paper compares characteristics of three steel types - one standardized in EN 10106 (M235-35A) and two special steel alloys - Arnon5 and Hiperco 50. The iron core loss characteristics are derived to describe the dependence of loss number on magnetic flux density and frequency. Based on obtained results the application field of each material is discussed

Impact of electrical machine structural parts on its modal and vibration behavior

In the paper, authors deal with the case study of an impact of stator frame and vertical mounting on modal and vibration behavior of a squirrel-cage induction machine. The study is performed using finite element analysis where resulting magnetic forces from magnetic transient analysis are set as an excitation in the analysis of harmonic response. Modal analysis is carried out to identify the modes and natural frequencies of the modeled structures and their possible effect on vibration spectra. Resulting vibration spectra are compared to the analysis of a solely stator lamination and to the experimental results on the full machine assembly

Analysis of traction permanent magnet motor with static and dynamic eccentricities

In the paper, electromagnetic and vibration analyses of traction electric machine exhibiting static and dynamic eccentricities is performed. The machine is a highspeed permanent magnet synchronous motor with surfacemounted permanent magnets and double-layer concentrated winding. The machine is intended for use in a compact drive unit in the applications such as light rail vehicles, trams or metro wagons. Vibration of electromagnetic origin are examined using finite element analysis and referenced to the machine in a perfect technical condition. Moreover, impact of the both eccentricities on stator phase currents and torques is analyzed

Current in broken squirrel cage of induction machine

The paper deals with the squirrel cage of an induction motor. Faulty connection between the rotor bar and the end-ring has a fundamental effect on the magnitude of the current of an affecting bar and surrounding bars as well. By the matrix equation is solved the current distribution in the damaged bars of a squirrel cage. The thermal dilatation of the bars is also observed. Unsymmetrical thermal stress on thebars causes them to different dilatation and leads to further development of the fault

Experimental verification of the finite element analysis of an induction machine with implemented static eccentricity fault

The paper deals with the experimental verification of vibration frequency spectra of squirrel-cage induction machine having implemented static eccentricity fault. The measured data are compared to the theoretical presumptions and the transient finite element analysis of the measured machine. Measurement and finite element model are carried out for the machine in a perfect technical condition as well and those specify the reference point for the faulty machine

Vibration analysis of a nine-phase induction machine supplied by voltage with harmonics injection

The paper deals with magnetic forces and vibration analysis of a nine-phase induction motor. It is described a method of voltage harmonics injection for reaching either the same amplitude or RMS value of supplying voltage as for the case of supplying the motor using the voltage fundamental only. Influence of the both types of voltage harmonics injection on the magnetic forces and motor vibration is evaluated using finite element analysis and compared to the motor supply by sinusoidal voltage