Influence of rotor endcaps on the electromagnetic performance of high-speed PM machine

Influence of rotor endcaps on the electromagnetic performance of high-speed PM machine

For access to this article, please select a purchase option:

Buy article PDF
(plus tax if applicable)
Buy Knowledge Pack
10 articles for £75.00
(plus taxes if applicable)

IET members benefit from discounts to all IET publications and free access to E&T Magazine. If you are an IET member, log in to your account and the discounts will automatically be applied.

Learn more about IET membership 

Recommend Title Publication to library

You must fill out fields marked with: *

Librarian details
Your details
Why are you recommending this title?
Select reason:
IET Electric Power Applications — Recommend this title to your library

Thank you

Your recommendation has been sent to your librarian.

Surface-mounted permanent magnet (SPM) machines are preferred for high-speed aerospace applications over induction and switched reluctance machines, since they combine the advantages of high torque density and efficiency. Also, in aerospace applications, where low rotor weight and inertia are essential requirements, a permeable hollow shaft is proposed to replace the need for rotor back-iron and reduce the overall rotor weight. For rotor mechanical integrity, a retaining sleeve is commonly used, leading to thicker magnetic airgap. Furthermore, when permeable rotor endcaps are applied, an increase of the magnetic end leakage occurs, i.e. end-effect. In this study, the influence of the rotor endcaps on the mechanical and electromagnetic performance of a high-speed SPM machine is investigated through 3D-finite element analyses. Also, different endcap thickness and different rotor shaft materials are investigated and compared in this work. Finally, a prototype of the SPM machine under study has been manufactured and tested. The comparison between simulation and experimental results is presented and discussed.


    1. 1)
      • 1. Gerada, D., Mebarki, A., Brown, N., et al: ‘High-speed electrical machines: technologies, trends, and developments’, IEEE Trans. Ind. Electron., 2014, 61, (6), pp. 29462959.
    2. 2)
      • 2. Al-Timimy, A., Degano, M., Giangrande, P., et al: ‘Design and optimization of a high power density machine for flooded industrial pump’. International Conf. Electrical Machines, Lausanne, 2016, pp. 14801486.
    3. 3)
      • 3. Wang, J., Xia, X., Howe, D.: ‘Three-phase modular permanent magnet brushless machine for torque boosting on a down-seized ICE vehicles’, IEEE Trans. Veh. Technol., 2005, 54, (3), pp. 809816.
    4. 4)
      • 4. El-Refaie, A., Jahns, T.: ‘Optimal flux-weakening in surface PM machines using concentrated windings’, IEEE Trans. Ind. Appl., 2005, 41, (3), pp. 790800.
    5. 5)
      • 5. Vagati, A., Pellegrino, G., Guglielmi, P.: ‘Comparison between SPM and IPM motor drives for EV applications’. International Conf. Electrical Machines, Rome, 2010, pp. 16.
    6. 6)
      • 6. Wang, J., Yuan, X., Atallah, K.: ‘Design optimization of a surface-mounted permanent magnet motor with concentrated windings for electric vehicle applications’, IEEE Trans. Veh. Technol., 2013, 62, (3), pp. 10531064.
    7. 7)
      • 7. Azzouzi, J., Barakat, G., Dakyo, B.: ‘Quasi-3-D analytical modeling of the magnetic field of an axial flux permanent-magnet synchronous machine’, IEEE Trans. Energy Convers., 2005, 20, (4), pp. 746752.
    8. 8)
      • 8. Platen, M., Henneberger, G.: ‘Examination of leakage and end effects in a linear synchronous motor for vertical transportation by means of finite element computation’, IEEE Trans. Mag., 2008, 37, (5), pp. 36403643.
    9. 9)
      • 9. Yu, C., Zhu, Z., Howe, D.: ‘Three-dimensional lumped-parameter magnetic circuit analysis of single-phase flux-switching permanent-magnet motor’, IEEE Trans. Mag., 2008, 44, (6), pp. 17011710.
    10. 10)
      • 10. Sanada, M., Morimoto, S., Takeda, Y.: ‘Interior permanent magnet linear synchronous motor for high-performance drives’, IEEE Trans. Ind. Appl., 1997, 33, (4), pp. 966972.
    11. 11)
      • 11. Polinder, H., Slootweg, J., Hoeijmakers, M., et al: ‘Modeling of a liner PM machine including magnetic saturation and end effects: maximum force-to-current ratio’, IEEE Trans. Ind. Appl., 2003, 39, (6), pp. 16811688.
    12. 12)
      • 12. Hua, W., Cheng, M., Zhu, X., et al: ‘Investigation of end-effect in brushless machines having magnets in the stator with doubly salient structure’. IEEE Int. Magnetics Conf., San Diego, CA, 2006, p. 197.
    13. 13)
      • 13. Zhu, X., Cheng, M., Hua, W., et al: ‘Investigation of end-effect and experimental validation for hybrid excited doubly salient machine’. 12th Biennial IEEE Conf., Miami, FL, 2006, p. 320.
    14. 14)
      • 14. Zhu, Z., Chen, J., Pang, Y., et al: ‘Modeling of end-effect in flux-switching permanent magnet machines’. Int. Conf. Electrical Machines Systems, Seoul, 2007, pp. 943948.
    15. 15)
      • 15. Zhu, Z., Pang, Y., Hua, W., et al: ‘Investigation of end effect in permanent magnet brushless machines having magnets on the stator’, J. Appl. Phys., 2006, 99, (8), pp. 319323.
    16. 16)
      • 16. Zhu, Z., Azar, Z.: ‘Influence of end-effect and cross-coupling on torque-speed characteristics of switched flux permanent magnet machines’. 8th Int. Conf. Power Electron., Jeju, 2011, pp. 145152.
    17. 17)
      • 17. Al-Timimy, A., Degano, M., Xu, Z., et al: ‘Trade-off analysis and design of a high power density PM machine for flooded industrial pump’. IECON, Florence, 2016, pp. 17491754.
    18. 18)
      • 18. Xu, Z., Al-Timimy, A., Degano, M., et al: ‘Thermal management of a permanent magnet motor for a directly coupled pump’. International Conf. Electrical Machines, Lausanne, 2016, pp. 27382744.
    19. 19)
      • 19. Galea, M., Gerada, C., Raminosoa, T., et al: ‘Design of a high force density tubular permanent magnet motor’. XIX Int. Conf. Electrical Machines (ICEM), Rome, 2010, pp. 16.
    20. 20)
      • 20. Barrans, S., Al-ani, M., Carter, J.: ‘Mechanical design of rotors for permanent magnet high-speed electric motors for turbocharger applications’, IEEE Trans. Elect. Syst. Transp., 2017, 7, (4), pp. 278286.
    21. 21)
      • 21. Al-ani, M., Zhu, Z.: ‘Influence of end-effect on torque-speed characteristics of various switched flux permanent magnet machine topologies’, COMPEL, 2015, 35, (2), pp. 525539.
    22. 22)
      • 22. Mohammed, A.M., Cox, T., Galea, M., et al: ‘A new method for determining the magnetic properties of solid materials employed in unconventional magnetic circuits’, IEEE Trans. Ind. Electron., 2017, 64, (3), pp. 24682475.
    23. 23)
      • 23. Hanselman, D.C.: ‘Brushless permanent magnet motor design’ (The Writers’ Collective, New York, 2003).
    24. 24)
      • 24. Qi, G., Chen, J., Zhu, Z., et al: ‘Influence of skew and cross-coupling on flux-weakening performance of permanent-magnet brushless AC machines’, IEEE Trans. Mag., 2009, 45, (5), pp. 21102117.
    25. 25)
      • 25. Soong, W., Miller, T.: ‘Field-weakening performance of brushless synchronous AC motor drive’, IEE Porc. Elect. Power Appl., 1994, 141, (6), pp. 331340.
    26. 26)
      • 26. Silva, V., Meunier, G., Foggia, A.: ‘A 3D finite-element computation of eddy currents losses in the stator end lamination of large synchronous machines’, IEEE Trans. Mag., 1996, 32, (3), pp. 15691572.
    27. 27)
      • 27. Van Der Veen, J., Offringa, L., Vandenput, A.: ‘Minimizing rotor losses in high-speed high-power permanent magnet synchronous generators with rectifier load’, IEE Porc. Elect. Power Appl., 1997, 144, (5), pp. 3313337.

Related content

This is a required field
Please enter a valid email address