The Effect of Dynamic Eccentricity on Induction Machine Stator Currents (Part A)

Authors: Saleh S. Hamad Elawgali

Abstract:

Current spectrums of a high power induction machine was calculated for the cases of full symmetry, static and dynamic eccentricity. The calculations involve integration of 93 electrical plus four mechanical ordinary differential equations. Electrical equations account for variable inductances affected by slotting and eccentricities. The calculations were followed by Fourier analysis of the stator currents in steady state operation. The paper presents the stator current spectrums in full symmetry, static and dynamic eccentricity cases, and demonstrates the harmonics present in each case. The effect of dynamic eccentricity is demonstrating via comparing the current spectrums related to dynamic eccentricity cases with the full symmetry one. The paper includes one case study, refers to dynamic eccentricity, to present the spectrum of the measured current and demonstrate the existence of the harmonics related to dynamic eccentricity. The zooms of current spectrums around the main slot harmonic zone are included to simplify the comparison and prove the existence of the dynamic eccentricity harmonics in both calculated and measured current spectrums.

Keywords: Current spectrum, diagnostics, harmonics, Induction machine

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1331001

References:

[1] V. Devanneaux, H. Kabbaj, B. Dagues, and J. Faucher, "A versatile model of squirrel cage induction machines for design, monitoring and diagnosis purposes," 9th European Conference on Power Electronics and Applications, Auguest, 2001.
[2] A. Bellini, F. Filippetti, G. Franceschini, and C. Tassoni, "Towards correct quantification of induction machines broken bars through input electrical signals", International Conference on Electrical Machines, ICEM-2000, 28-30 August 2000, Espoo, Finland, pp. 781-785.
[3] A. Bellini, F. Filippetti, G. Franceschini, and C. Tassoni, "Quantitative evaluation of induction motor broken bars by means of electrical signature analysis", IEEE, Transactions on Industry Applications, vol. 37 No. 5, pp. 1248-55. 2001.
[4] A. Lebaroud, A. Bentousi, A. Kkhezzar, M. Boucherma. "Effects of broken bar of induction motor with stator asymmetry and distorted supply ", International Conference on Electrical Machines, ICEM-2004, 5-8 September 2004, Cracow, Poland, pp. 795-796.
[5] Saleh Elawgali. "Effect of combined eccentricities on the spectrum of induction machine currents", XL International Symposium on Electrical Machines, SME-2004, 15-18 June 2004, Hajnowka, Poland, pp. 457- 462.
[6] Saleh Elawgali. "Current spectrums of a 3.15 MW induction machine based on diagnostic oriented calculations ", Elektrotechnika i Elektronika, AGH Uczelniane Wydawnictwa Naukowo-Dydaktyczne, tom 23. zeszyt 1, pp. 14-26, Krakow 2004.
[7] Saleh Elawgali. "Effect of eccentricities and cage asymmetry on the induction machine currents, considering deformation of supply voltages", International Conference on Electrical Machines, ICEM-2004, 5-8 September 2004, Cracow, Poland, pp. 443-444.
[8] J. Rusek, "Computer implementation of induction machine dynamical model accounting for broken bars, eccentricities, slotting and parallel branches", International Conference on Electrical Machines, ICEM-2000, 28-30 August 2000, Espoo, Finland, pp. 868-872.
[9] J. Rusek, "Category, slot harmonics and the torque of induction machines", The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, COMPEL, vol. 22 no. 2, pp. 388-409, 2003.
[10] J. Rusek, “Categorization of induction machines resulting from their harmonic-balance model”, Electromagnetics, vol. 23, No. 3, April 2003, Taylor & Francis, pp. 277-292.
[11] V. Devanneaux, H. Kabbaj, B. Dagues, and J. Faucher, “An accurate model of squirrel cage induction machines under static, dynamic or mixed eccentricity”, IEEE International Symposium on Diagnostics for Electric Machines, Power Electronics and Drives, SDEMPED, 1-3 September 2001, Grado, Italy, pp. 121-126.
[12] W. T. Thomson, and A. Barbour, “On-line current monitoring and application of a finite element method to predict the level of static air gap eccentricity in three-phase induction motors”, IEEE Transaction on Energy Conversion, vol. 13, No. 4, December 1998, pp. 347-354.