Progress In Electromagnetics Research B
ISSN: 1937-6472
Home | Search | Notification | Authors | Submission | PIERS Home | EM Academy
Home > Vol. 40 > pp. 1-29


By U. Ausserlechner

Full Article PDF (723 KB)

Axial permanent magnetic couplings are composed of two discs with a small air-gap in-between. Each disc consists of several segments in the shape of slices of cakes. The segments are polarized in axial direction with alternating polarity. In this work the homogeneous magnetization in the segments is replaced by equivalent currents on the surface of the segments (Amperean model). In a simplified model we consider only radial currents whereas azimuthal currents along the perimeter of the discs are discarded. This corresponds to the arrangement where one of the discs has much larger diameter than the other disc. Compared to the case of two equal discs it leads to a notable error in the magnetic field near the perimeter, yet it has only a small effect on the torque, especially for the case of optimum couplings. This trick allows for summing up the fields of all segments in closed form. A concise double integral over the radial magnetic field component describes the torque. An investigation of this integral reveals many properties of axial magnetic couplings: A diagram is introduced and areas in this diagram are identified where the torque shows overshoot, rectangular pulse shape or sinusoidal dependence versus twist angle between bothdiscs. The diagram contains also a curve for maximum torque and one point on this curve is of considerable economic significance: It denotes the global maximum of torque over magnet mass.

U. Ausserlechner, "The Maximum Torque of Synchronous Axial Permanent Magnetic Couplings," Progress In Electromagnetics Research B, Vol. 40, 1-29, 2012.

1. Ausserlechner, U., "Closed analytical formulae for multi-pole magnetic rings," Progress In Electromagnetics Research B, Vol. 38, 71-105, 2012.

2. Bancel, F. and G. Lemarquand, "Three-dimensional analytical optimization of permanent magnets alternated structure," IEEE Trans. Magn., Vol. 34, No. 1, 242-247, Jan. 1998.

3. Bancel, F., "Magnetic nodes," J. Phys. D: Appl. Phys., Vol. 32, 2155-2161, 1999.

4. Liu, W. Z., C. Y. Xu, and Z. Y. Ren, Research of the surface magnetic field of multi-pole magnetic drum of magnetic encoder, Int'l Conf. Sensors and Control Techniques, Proceedings of SPIE, D.-S. Jiang and A.-B. Wang, editors, Vol. 4077, 288-291, 2000.

5. Furlani, E. P., "A three-dimensional field solution for axially-polarized multipole discs," J. Magn. Magn. Mat., Vol. 135, 205-214, 1994.

6. Ravaud, R. and G. Lemarquand, "Magnetic field created by a uniformly magnetized tile permanent magnet," Progress In Electromagnetics Research B, Vol. 24, 17-32, 2010.

7. Ravaud, R., G. Lemarquand, V. Lemarquand, and C. Depollier, "Magnetic field produced by a tile permanent magnet whose polarization is both uniform and tangential," Progress In Electromagnetics Research B, Vol. 13, 1-20, 2009.

8. Ravaud, R. and G. Lemarquand, "Analytical expression of the magnetic field created by tile permanent magnets tangentially magnetized and radial currents in massive disks," Progress In Electromagnetics Research B, Vol. 13, 309-328, 2009.

9. Nihei, H., "Analytic expressions of magnetic multipole field generated by a row of permanent magnets," Jap. J. Appl. Phys., Vol. 29, No. 9, 1831-1832, Sept. 1990.

10. Ozeretskovskiy, V., "Calculation of two-dimensional nonperiodic multipole magnetic systems," Sov. J. Commun. Techn. and Electr., Vol. 36, No. 8, 81-92, Aug. 1991.

11. Grinberg, E., "On determination of properties of some potential fields ," Applied Magnetohydrodynamics, Reports of the Physics Inst. Riga, Vol. 12, 147-154, 1961.

12. Avilov, V. V., "Electric and magnetic fields for the riga plate," Internal Report FZR Forschungszentrum Rossendorf, Dresden, Germany, 1998. Published in a report by E. Kneisel, ``Numerische und experimentelle untersuchungen zur grenzschichtbee-inflüssung in schwach leitfähigen flüssigkeiten," Nov. 24, 2003, http://www.hzdr.de/FWS/FWSH/Mutschke/kleinerbeleg.pdf.

13. De Visschere, P., "An exact two-dimensional model for a periodic circular array of head-to-head permanent magnets," J. Phys. D: Appl. Phys., Vol. 38, 355-362, 2005.

14. Furlani, E. P. and M. A. Knewtson, "A three-dimensional field solution for permanent-magnet axial-field motors," IEEE Trans. Magn., Vol. 33, No. 3, 2322-2325, May 1997.

15. Furlani, E. P., "Analytical analysis of magnetically coupled multipole cylinders," J. Phys. D: Appl. Phys., Vol. 33, 28-33, 2000.

16. Ravaud, R. and G. Lemarquand, "Magnetic couplings with cylindrical and plane air gaps: Influence of the magnet polarization direction," Progress In Electromagnetics Research B, Vol. 16, 333-349, 2009.

17. Ravaud, R., G. Lemarquand, V. Lemarquand, and C. Depollier, "Torque in PM couplings: Comparison of uniform and radial magnetization," J. Appl. Phys., Vol. 105, 053904, 2009, DOI: 10.1063/1.3074108.

18. Ravaud, R., G. Lemarquand, V. Lemarquand, and C. Depollier, "Permanent magnet couplings: Field and torque three-dimensional expressions based on the coulombian model," IEEE Trans. Magn., Vol. 45, No. 4, 195-1964, 2009.

19. Yao, Y. D., G. J. Chiou, D. R. Huang, and S. J. Wang, "Theoretical computations for the torque of magnetic coupling," IEEE Trans. Magn., Vol. 31, No. 3, 1881-1884, May 1995.

20. Huang, D. R., G.-J. Chiou, Y.-D. Yao, and S.-J. Wang, "Effect of magnetization profiles on the torque of magnetic coupling," J. Appl. Phys., Vol. 76, No. 10, 6862-6864, Nov. 1994.

21. Yao, Y. D., D. R. Huang, C. C. Hsieh, D. Y. Chiang, S. J. Wang, and T. F. Ying, "The radial magnetic coupling studies of perpendicular magnetic gears," IEEE Trans. Magn., Vol. 32, No. 5, 5061-5063, Sept. 1996.

22. Tsamakis, D., M. Ioannides, and G. Nicolaides, "Torque transfer through plastic bonded Nd2Fe14B magnetic gear system," J. Alloys Compounds, Vol. 241, 175-179, 1996.

23. Nagrial, M. H., J. Rizk, and A. Hellany, "Design of synchronous torque couplers," World Academy of Science, Engineering and Technology, Vol. 79, 426-431, 2001.

24. Furlani, E. P., "Formulas for the force and torque of axial couplings," IEEE Trans. Magn., Vol. 29, No. 5, 2295-2301, 1993.

25. Furlani, E. P., "Analysis and optimization of synchronous magnetic couplings," J. Appl. Physics, Vol. 79, No. 8, 4692-4694, 1996.

26. Furlani, E. P., "Field analysis and optimization of axial field permanent magnet motors," IEEE Trans. Magn., Vol. 33, No. 5, 3883-3885, 1997.

27. Furlani, E. P., "Computing the field in permanent-magnet axial-field motors," IEEE Trans. Magn., Vol. 30, No. 5, 3660-3663, 1994.

28. Furlani, E. P., "A method for predicting the field in permanent magnet axial-field motors," IEEE Trans. Magn., Vol. 28, No. 5, 2061-2066, 1992.

29. Nagrial, M. H., "Design optimization of magnetic couplings using high energy magnets," Electr. Machines and Power Systems, Vol. 21, No. 1, 115-126, 1993.

30. Lubin, T., S. Mezani, and A. Rezzoug, "Simple analytical expressions for the force and torque of axial magnetic couplings," IEEE Trans. Energy Conversion, Vol. 99, 1-11, 2012.

31. Zheng, P., Y. Haik, M. Kilani, and C.-J. Chen, "Force and torque characteristics for magnetically driven blood pump," J. Magn. Magn. Mat., Vol. 241, 292-302, 2002.

32. Kellog, O. D., "Electric images: Infinite series of images," Foundations of Potential Theory, Chapter IX 1, 230, Dover Publications, Inc., NY, 1954, ISBN 0-486-60144-7.

33. Furlani, E. P., "Axial-field motor," Permanent Magnet and Electromechanical Devices, Chapter 5.13, Fig. 5.44, 434, Academic Press, San Diego, 2001, ISBN 0-12-269951-3.

34. Waring, R., J. Hall, K. Pullen, and M. R. Etemad, "An investigation of face type magnetic couplers," Proc. Inst. Mech. Eng. A, J. Power and Energy, Vol. 210, No. 4, 263-272, 1996.

© Copyright 2010 EMW Publishing. All Rights Reserved