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.

Analytical Prediction of the Electromagnetic Torques in Single-Phase and Two-Phase AC Motors

Mircea Popescu

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 S4 at Helsinki University of Technology (Espoo, Finland) on the 3rd of September, 2004, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-7222-9)   [1067 KB]
Dissertation is also available in print (ISBN 951-22-7186-9)


The single-phase and two-phase versions of AC motors can be modelled by means of the two-axis (d-q) theory with sufficient accuracy when the equivalent circuit parameters are correctly estimated. This work attempts to present a unified approach to the analytical prediction of the electromagnetic torque of these machines.

Classical d-q axes formulation requires that the reference frame should be fixed on the frame where the asymmetries arise, i.e. the stator and rotor. The asynchronous torques that characterize the induction motors are modelled in a stationary reference frame, where the d-q axes coincide with the physical magnetic axes of the stator windings. For the permanent magnet motors, that may exhibit asymmetries on both stator and rotor, the proposed solution includes: a series of frame transformations, followed by symmetrical components decomposition. As in single-phase and two-phase systems the homopolar component is zero; each symmetrical component – negative and positive – is further analysed using d-q axes theory. The superposition principle is employed to consider the magnets and rotor cage effects.

The developed models account for the most important asymmetries of the motor configuration. These are, from the stator point of view, different distribution, conductors' dimensions and number of effective turns, non-orthogonal magnetic axes windings and from the rotor point of view, asymmetrical rotor cage, variable reluctance, and permanent magnets effect. The time and space harmonics effect is ignored. Test data are compared with the computed data in order to observe how the simplifying assumptions affect the level of accuracy.

The analytical prediction methods make possible torque computation according to the nature of the torque being computed, namely, induction, reluctance and excitation (permanent magnet). The results are available for quasi steady-state, steady-state (rated or synchronous speed) and dynamic analyses. All the developed mathematical models can be used in preliminary design for further optimisation and accurate estimation in complex numerical models. Another important feature of the analytical models for single-phase and two-phase AC motors, is that they can be directly implemented in any suitable electrical drives control strategy.

This thesis consists of an overview and of the following 8 publications:

  1. Popescu M., Arkkio A., Micu D., Demeter E. and Navrapescu V., 1998. Development of an inverter fed two-phase variable speed induction motor drive. In: Conference Records of the 8th International Power Electronics and Motion Control Conference (PEMC'98). Prague, Czech Republic, 5-8 September 1998, pages 4-132 - 4-136. © 1998 by authors.
  2. Popescu M., Demeter E., Jokinen T. and Navrapescu V., 1999. Modeling and analysis of a two-phase induction machine with non-orthogonal stator windings. In: Conference Records of the IEEE International Electric Machines and Drives Conference (IEMDC'99). Seattle, USA, 9-12 May 1999, pages 389-391. © 1999 IEEE. By permission.
  3. Popescu M., Jokinen T., Lampola P., Arkkio A., Demeter E. and Navrapescu V., 1999. Analysis of the electrical shift angle influence over a variable speed two-phase induction motor drive. In: Conference Records of the 8th European Conference on Power Electronics and Applications (EPE'99). Lausanne, Switzerland, 7-9 September 1999, 8 pages. © 1999 by authors.
  4. Popescu M. and Navrapescu V., 2000. Modelling in stationary frame reference of single and two-phase induction machines including the effect of iron loss and magnetising flux saturation. In: Conference Records of the International Conference on Electrical Machines (ICEM 2000). Espoo, Finland, 28-30 August 2000, volume 1, pages 407-411. © 2000 by authors.
  5. Popescu M., Miller T. J. E., McGilp M., Strappazzon G., Trivillin N. and Santarossa R., 2004. Asynchronous performance analysis of a single-phase capacitor-start, capacitor-run permanent magnet motor. IEEE Transactions on Energy Conversion, accepted for publication. © 2004 IEEE. By permission.
  6. Popescu M., Miller T. J. E., McGilp M. I., Strappazzon G., Trivillin N. and Santarossa R., 2003. Line-start permanent-magnet motor: single-phase starting performance analysis. IEEE Transactions on Industry Applications 39, number 4, pages 1021-1030. © 2003 IEEE. By permission.
  7. Popescu M., Ionel D. M., Dellinger S., Miller T. J. E. and McGilp M., 2004. Analysis and design of a two-speed single-phase induction motor with 2 and 18 pole special windings. IEEE Transactions on Energy Conversion, accepted for publication. © 2004 IEEE. By permission.
  8. Popescu M., Miller T. J. E., McGilp M. I., Strappazzon G., Trivillin N. and Santarossa R., 2003. Torque behaviour of 1-phase permanent magnet AC motor. In: Conference Record of the IEEE International Electric Machines and Drives Conference (IEMDC'03). Madison, USA, 1-4 June 2003, pages 820-825. © 2003 IEEE. By permission.

Keywords: single-phase, two-phase, induction motors, permanent magnet motors, electromagnetic torque, special windings

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© 2004 Helsinki University of Technology

Last update 2011-05-26