volume | PIER Journals

Abstract

A 2D finite element electromagnetic model that permits the simulation of a cage induction machine, involving the effects of eddy currents and coupling the field equation with the stator field-circuit equation, has been presented in this paper. Transformation matrix has been derived to incorporate specialized stator winding scheme called the bridge configured winding (BCW) in the coupled field circuit equation. The bridge configured winding scheme is capable of producing controllable transverse force by deliberately imparting asymmetric flux distribution in the machine air-gap. Steady state stator currents have been calculated using the time-stepping scheme with the rotor motion at constant speed allowing the FE model to take into account the harmonics due to the eccentricity (static) of the rotor. This work has furnished us with the 2D magnetic flux distribution in the whole finite element domain as well as sets out an electromagnetic model to study the electromechanical interaction between the eccentric rotor motion and the electromagnetic field. The results, in terms of variation of terminal currents (phase and bridge) and unbalanced magnetic pull (UMP) due to rotor eccentricity as well as asymmetric field (deliberately imparted by exciting the bridge), obtained from the simulation have been compared with analytical formulations as well as already published experimental results.

1. Salon, S. J., M. J. DeBortoli, and R. Palma, "Coupling of transient fields, circuits, and motion using finite element analysis," Journal of Electromagnetic Waves and Applications, Vol. 4, No. 11, 1077-1106, 1990. Google Scholar

2. Savov, V. N., Z. D. Georgiev, and E. S. Bogdanov, "Analysis of cage induction motor by means of the finite element method and coupled system of field, circuit and motion equations," Electrical Engineering, Vol. 80, 21-28, Springer-Verlag, 1997. Google Scholar

3. Wang, X. and D. Xie, "Analysis of induction motor using field-circuit coupled time-periodic finite element method taking account of hysteresis," IEEE Transactions on Magnetics, Vol. 45, No. 3, 1740-1743, 2009.
doi:10.1109/TMAG.2009.2012802 Google Scholar

4. Ho, S. L., S. Niu, W. N. Fu, and J. Zhu, "A power-balanced time-stepping finite element method for transient magnetic field computation," IEEE Transactions on Magnetics, Vol. 48, No. 2, 291-294, 2012.
doi:10.1109/TMAG.2011.2173911 Google Scholar

5. Ovando-Martinez, R. B. B., M. A. Arjona Lopez, and C. H. Flores, "A finite-element variable time-stepping algorithm for solving the electromagnetic diffusion equation," IEEE Transactions on Magnetics, Vol. 48, No. 2, 647-650, 2012.
doi:10.1109/TMAG.2011.2177448 Google Scholar

6. Khoo, W. K. S., "Bridge configured winding for poly-phase self-bearing machines," IEEE Transactions on Magnetics, Vol. 41, No. 4, 1289-1295, 2005.
doi:10.1109/TMAG.2005.845837 Google Scholar

7. Salazar, A. O. and R. M. Stephan, "A bearing-less method for induction machine," IEEE Transactions on Magnetics, Vol. 29, No. 6, 2965-2967, 1993.
doi:10.1109/20.280902 Google Scholar

8. Chiba, A., T. Deido, T. Fukao, and M. A. Rahman, "An analysis of bearingless AC motors," IEEE Transactions on Energy Conversion, Vol. 9, No. 1, 61-67, 1994.
doi:10.1109/60.282477 Google Scholar

9. Chiba, A., K. Sotome, Y. Iiyama, and M. A. Rahman, "A novel middle-point-current-injection-type bearing-less PM synchronous motor for vibration suppression," IEEE Transactions on Industrial Applications, Vol. 47, No. 4, 1700-1706, 2011.
doi:10.1109/TIA.2011.2155611 Google Scholar

10. Laiho, A., K. Tammi, J. Orivuori, A. Sinervo, K. Zenger, and A. Arkkio, "Electromechanical interaction in eccentric-rotor cage induction machine equipped with a self-bearing force actuator," Journal of System Design and Dynamics, Vol. 3, No. 4, 519-529, 2009.
doi:10.1299/jsdd.3.519 Google Scholar

11. Holopainen, T., A. Tenhunen, and A. Arkkio, "Electromechanical interaction in rotor-dynamics of cage induction motors," Journal of Sound Vibration, Vol. 284, 733-755, 2005.
doi:10.1016/j.jsv.2004.07.007 Google Scholar

12. Khoo, W. K. S., K. Kalita, and S. D. Garvey, "Practical implementation of the bridge configured winding for production of controllable transverse forces in electrical machines," IEEE Transactions on Magnetics, Vol. 47, No. 6, 1712-1718, 2011.
doi:10.1109/TMAG.2011.2113377 Google Scholar

13. Pham, T. H., P. F. Wendling, S. J. Salon, and H. Acikgoz, "Transient finite element analysis of an induction motor with external circuit connections and electromechanical coupling," IEEE Transactions on Magnetics, Vol. 14, No. 4, 1407-1412, 1999. Google Scholar

14. Bastos, J. P. A. and N. Sadowski, "Electromagnetic modeling by finite element methods,", Founding Edition, 490, Marcel Dekker, Inc., New York, USA, 2003, ISBN: 0-8247-4269-9. Google Scholar

15. Kalita, K., "Integrating rotor-dynamic and electromagnetic dynamic models for °exible-rotor electrical machines,", Ph.D. Thesis, The University of Nottingham, 2007. Google Scholar

16. Nandi, S., R. M. Bharadwaj, and H. A. Toliyat, "Performance analysis of a three-phase induction motor under mixed eccentricity condition," IEEE Transactions on Energy Conversion, Vol. 17, No. 3, 392-399, 2002.
doi:10.1109/TEC.2002.801995 Google Scholar

17. Kalita, K. and A. Laiho, "Dynamics of bridge-configured built-in force actuator for vibration control in four-pole cage induction machine," National Symposium on Rotor Dynamics, Chennai, India, December 19-21, 2011. Google Scholar

Dr. Rajkumar Singha Konwar

Prof. Karuna Kalita

Dr. Atanu Banerjee

Dr. Wee Keong Steve Khoo