Vol. 93

Front:[PDF file] Back:[PDF file]
Latest Volume
All Volumes
All Issues

A New Speed Multiplier Coaxial Magnetic Gear

By Mohd Firdaus Mohd Ab Halim, Erwan Bin Sulaiman, Raja Nor Firdaus, and Azhan Ab. Rahman
Progress In Electromagnetics Research M, Vol. 93, 145-154, 2020


Due to certain conditions, electrical motor (EM) that operates at high speed may lead to magnetic saturation, thermal issue and stress to rotor structure. Magnetic gear (MG) designed for speed multiplier enables the prime mover from EM to operate at lower speed while the output gear multiplies the speed by its designated gear ratio at reduced torque. In this paper, a new coaxial magnetic gear is designed for speed multiplier. The role between inner yoke with PM and pole piece is switched. The inner part of magnetic gear is made to be stationary while the pole piece becomes inner rotor. The working principle is presented analytically. It used flux modulation techniques for torque and speed transmission. Torque characteristic and gear efficiency is analysed using finite element, and compared with existing speed multiplier magnetic gear with the same gear ratio of 7/3. Based on the simulation result, the proposed speed multiplier MG offers 16% better torque density and 12% higher gear efficiency at higher speed range. The structure of the inner rotor was also found to be more robust as only pole piece ring together with plastic is rotated instead of yoke with PM.


Mohd Firdaus Mohd Ab Halim, Erwan Bin Sulaiman, Raja Nor Firdaus, and Azhan Ab. Rahman, "A New Speed Multiplier Coaxial Magnetic Gear," Progress In Electromagnetics Research M, Vol. 93, 145-154, 2020.


    1. Atay, F. M., "Magnetic saturation and steady-state analysis of electrical motors," Appl. Math. Model., Vol. 24, No. 11, 827-842, 2000.

    2. Ahn, J.-W. and G. F. L. Lukman, "Switched reluctance motor: Research trends and overview," China Electrotech. Soc. Trans. Electr. Mach. Syst., Vol. 2, No. 4, 339-347, 2019.

    3. Ion, B. and T. Lucian, Reluctance Electric Machines: Design and Control, 2018.

    4. Chen, L. L., C. S. Zhu, Z. Zhong, B. Liu, and A. Wan, "Rotor strength analysis for high-speed segmented surface-mounted permanent magnet synchronous machines," IET Electr. Power Appl., Vol. 12, No. 7, 979-990, 2018.

    5. Dong, J., Y. Huang, L. Jin, and H. Lin, "Comparative study of surface-mounted and interior permanent-magnet motors for high-speed applications," IEEE Trans. Appl. Supercond., Vol. 26, No. 4, 26-29, 2016.

    6. Tuysuz, A., F. Meyer, M. Steichen, C. Zwyssig, and J. W. Kolar, "Advanced cooling methods for high-speed electrical machines," IEEE Trans. Ind. Appl., Vol. 53, No. 3, 2077-2087, 2017.

    7. Karim, N., How washing machines work, 2000, https://www.howstuffworks.com.

    8. Lombardo, T., Shifting gears on wind turbines, 2013, https://www.engineering.com.

    9. Atallah, K. and D. Howe, "A novel high-performance linear magnetic gear," IEEE Trans. Magn., Vol. 37, No. 4, 2844-2846, 2001.

    10. Atallah, K., S. D. Calverley, and D. Howe, "Design, analysis and realisation of a high-performance magnetic gear," IEE Proceedings — Electric Power Appl., Vol. 150, No. 2, 139-145, 2004.

    11. Atallah, K., S. D. Calverley, and D. Howe, "High-performance magnetic gears," J. Magn. Magn. Mater., Vol. 272–276, No. SUPPL. 1, 1727-1729, 2004.

    12. Tallerico, T. F., J. J. Scheidler, and Z. A. Cameron, "Electromagnetic mass and efficiency of magnetic gears for electrified aircraft," 2019 AIAA/IEEE Electr. Aircr. Technol. Symp., 1-25, August 2019.

    13. Kawanishi, K., K. Matsuo, T. Mizuno, K. Yamada, T. Okitsu, and K. Matsuse, "Development and performance of high-speed SPM synchronous machine," 2018 Int. Power Electron. Conf. IPECNiigata — ECCE Asia 2018, 169-176, 2018.

    14. Gouda, E., S. Mezani, L. Baghli, and A. Rezzoug, "Comparative study between mechanical and magnetic planetary gears," IEEE Trans. Magn., Vol. 47, No. 2, 439-450, 2011.

    15. Huang, C. C., M. C. Tsai, D. G. Dorrell, and B. J. Lin, "Development of a magnetic planetary gearbox," IEEE Trans. Magn., Vol. 44, No. 3, 403-412, 2008.

    16. Gim, C. S., E. J. Park, S. Y. Jung, and Y. J. Kim, "Torque characteristic analysis of coaxial magnetic gear according to fillet parameter of pole piece," ICEMS 2018 — 2018 21st Int. Conf. Electr. Mach. Syst., No. 1, 2557-2560, 2018.

    17. Wang, L. L., J. X. Shen, Y. Wang, and K. Wang, "A novel magnetic-geared outer-rotor permanent-magnet brushless motor," Proceedings of the 4th IET International Conference on Power Electronics and Drives 2008, 33-36, 2008.

    18. Jian, L., K. T. Chau, and J. Z. Jiang, "A magnetic-geared outer-rotor permanent-magnet brushless machine for wind power generation," IEEE Trans. Ind. Appl., Vol. 45, No. 3, 954-962, 2009.

    19. Sun, L., M. Cheng, and H. Jia, "Analysis of a novel magnetic-geared dual-rotor motor with complementary structure," IEEE Trans. Ind. Electron., Vol. 62, No. 11, 6737-6747, 2015.

    20. Pop, C. V. and D. Fodorean, "In-wheel motor with integrated magnetic gear for extended speed applications," 2016 Int. Symp. Power Electron. Electr. Drives, Autom. Motion, Vol. 1143, 413-418, 2016.

    21. Molokanov, O., P. Dergachev, S. Osipkin, E. Kuznetsova, and P. Kurbatov, "A novel double-rotor planetary magnetic gear," IEEE Trans. Magn., Vol. 54, No. 11, 1-5, 2018.

    22. Park, E. J., C. S. Kim, S. Y. Jung, and Y. J. Kim, "Dual magnetic gear for improved power density in high-gear-ratio applications," ICEMS 2018 — 2018 21st Int. Conf. Electr. Mach. Syst., 2529-2532, 2018.

    23. Gerber, S., Evaluation and design aspects of magnetic gears and magnetically geared electrical machines, Stellenbosch University, 2015.

    24. Neves, C. G. C. and A. F. F. Filho, "Magnetic gearing electromagnetic concepts," J. Microwaves, Optoelectron. Electromagn. Appl., Vol. 16, No. 1, 108-119, 2017.

    25. Joyce, D. E., Summary of trigonometric identities, 2020.

    26. Neves, C. G. C., D. L. Figueiredo, and A. S. Nunes, "Magnetic gear: A review," 2014 11th IEEE/IAS Int. Conf. Ind. Appl., 1-6, 2014.

    27. Lubin, T., S. Mezani, and A. Rezzoug, "Analytical computation of the magnetic field distribution in a magnetic gear," IEEE Trans. Magn., Vol. 46, No. 7, 2611-2621, 2010.

    28. Zhang, X., X. Liu, C. Wang, and Z. Chen, "Analysis and design optimization of a coaxial surface-mounted permanent-magnet magnetic gear," Energies, Vol. 7, 8535-8553, 2014.

    29. Ye, X., Kilowatt three-phase rotary transformer design for permanent magnet DC motor with on-rotor drive system, MID Sweden University, 2016.

    30. Tzanakis, I., M. Hodnett, I. V Bogdanov, S. S. Kozub, K. Sugo, and S. B. Kim, "Fundamental study on the magnetic field control method using multiple HTS coils for Magnetic Drug Delivery System Fundamental study on the magnetic field control method using multiple HTS coils for Magnetic Drug Delivery System," Journal of Physics: Conference Series, 1-6, 2017.

    31. I, E. M., E. Sulaiman, and A. Zarafi, "A high torque segmented outer rotor permanent magnet flux switching motor for motorcycle propulsion," MUCET 2017, Vol. 150, 1-6, 2018.

    32. Ridge, A. N., S. Ademi, R. A. Mcmahon, and H. Kelly, "Ferrite-based axial flux permanent magnet generator for wind turbines," J. Eng., Vol. 2019, No. PEMD 2018, 3942-3946, 2019.

    33. Kimiabeigi, M., J. D. Widmer, R. S. Sheridan, A. Walton, and R. Harris, "Design of high performance traction motors using cheaper grade of materials," 8th IET International Conference on Power Electronics, Machines and Drives (PEMD 2016), Vol. 1, 1-7, 2016.

    34. Kouhshahi, M. B., V. M. Acharya, M. Calvin, and J. Z. Bird, "Designing and experimentally testing a flux-focusing axial flux magnetic gear for an ocean generator application," IET Electr. Power Appl., Vol. 13, No. 8, 1212-1218, 2019.

    35. Cai, H., H. Wang, M. Li, S. Shen, Y. Feng, and J. Zheng, "Torque ripple reduction for switched reluctance motor with optimized PWM control strategy," Energies, Vol. 11, No. 11, 2018.

    36. Mateev, V. and I. Marinova, "Loss estimation of magnetic gears," Electr. Eng., No. 0123456789, 1-13, 2019.

    37. Filippini, M., et al., "Magnetic loss analysis in coaxial magnetic gears," Electron., Vol. 8, No. 11, 1-15, 2019.