The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
Aalto

Modelling the Unbalanced Magnetic Pull in Eccentric-Rotor Electrical Machines with Parallel Windings

Andrej Burakov

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S1 at Helsinki University of Technology (Espoo, Finland) on the 25th of October, 2007, at 12 noon.

Overview in PDF format (ISBN 978-951-22-9006-2)   [946 KB]
Dissertation is also available in print (ISBN 978-951-22-9005-5)

Abstract

This research work is focused on developing simple parametric models of the unbalanced magnetic pull produced in eccentric-rotor electrical machines. The influence of currents circulating in the parallel paths of the stator winding on the unbalanced magnetic pull is given the main attention. The interaction between these currents and those circulating in the rotor cage/damper winding is also considered.

First, a parametric force model for an eccentric-rotor salient-pole synchronous machine is developed. The effects of the parallel stator windings are not considered in this model. Next, a low-order parametric force model is built for electrical machines equipped with parallel stator windings but operating without the rotor cage/damper winding. This force model is applicable to salient-pole synchronous machines as well as to induction motors. And finally, a special force model is developed for electrical machines furnished with parallel paths both in the rotor and stator windings. This model accounts for the equalising currents circulating in the rotor and stator windings and also for the interaction between these currents. This third force model can be applied to a salient-pole synchronous machine and to an induction machine. The parameters of the force models are estimated from the results of numerical simulations applying a soft-computing-based estimation program. All the developed force models with the estimated parameters demonstrate a very good performance in a wide whirling frequency range.

The effects of parallel paths in the rotor and stator windings on the unbalanced magnetic pull are investigated numerically. The acquired results reveal that the total unbalanced magnetic pull and its constituents related to the fundamental magnetic field and slotting are strongly affected by the presence of parallel paths in the stator winding. However, unlike the rotor cage, parallel stator windings may instigate anisotropy in the unbalanced magnetic pull. In such cases, the results of the numerical impulse response test may differ significantly from the conventional calculation results. It is also shown that, despite the fact that the number of parallel paths in the stator is often substantially lower than the number of parallel paths in the rotor, parallel stator windings may still provide a more efficient UMP mitigation than the rotor cage/damper winding.

This thesis consists of an overview and of the following 7 publications:

  1. Burakov, A., Tenhunen, A., Arkkio, A. 2005. Applying Genetic Algorithms to identify the parameters of a low-order force model for a salient-pole synchronous machine with eccentric rotor. 8th International Conference on Modeling and Simulation of Electric Machines, Converters and Systems (ELECTRIMACS 2005), April 17-20, 2005, Hammamet, Tunisia, 5 p.
  2. Burakov, A., Arkkio, A. 2006. Low-order parametric force model for a salient-pole synchronous machine with eccentric rotor. Electrical Engineering (Archiv für Elektrotechnik), Springer Berlin / Heidelberg, Vol. 89, No. 2, pp. 127-136. © 2006 by authors and © 2006 Springer Science+Business Media. By permission.
  3. Burakov, A., Arkkio, A. 2006. Low-order parametric force model for eccentric-rotor electrical machine with parallel connections in stator winding. IEE Proceedings - Electric Power Applications, Vol. 153, Issue 4, pp. 592-600. © 2006 The Institution of Engineering and Technology (IET). By permission.
  4. Burakov, A., Arkkio, A. 2006. Validity of numerical impulse response test in studying unbalanced magnetic pull in electrical machines with parallel stator windings. Proceedings of the 17th International Conference on Electrical Machines (ICEM 2006), September 2-5, 2006, Chania, Crete Island, Greece, 5 p.
  5. Burakov, A., Arkkio, A. 2007. Low-order parametric force model for eccentric-rotor electrical machine equipped with parallel stator windings and rotor cage. IET Electric Power Applications, Vol. 1, Issue 4, pp. 532-542. © 2007 The Institution of Engineering and Technology (IET). By permission.
  6. Burakov, A., Arkkio, A. 2007. Mitigation of UMP components by the parallel stator windings in eccentric-rotor electrical machines. Proceedings of the 2007 IEEE International Electric Machines and Drives Conference (IEMDC 2007), May 3-5, 2007, Antalya, Turkey, pp. 1638-1642.
  7. Burakov, A., Arkkio, A. 2007. Comparison of the unbalanced magnetic pull mitigation by the parallel paths in the stator and rotor windings. IEEE Transactions on Magnetics, in press. © 2007 by authors and © 2007 IEEE. By permission.

Keywords: parallel windings, rotor eccentricity, unbalanced magnetic pull

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© 2007 Helsinki University of Technology

Last update 2011-05-26