Solid Core Magnetic Gear Systems: A Comprehensive Review of Topologies, Core Materials, and Emerging Applications
Source abstract
Abstract
Magnetic gears (MGs) are attracting increasing attention in power transmission systems due to their contactless operation principles, low frictional losses, and high efficiency. However, the broad application potential of these technologies requires a comprehensive evaluation of engineering parameters, such as material selection, energy efficiency, and structural design. This review focuses solely on solid-core magnetic gear systems designed using laminated electrical steels, soft magnetic composites (SMCs), and high-saturation alloys. This review systematically examines the topological diversity, torque transmission principles, and the impact of various core materials, such as electrical steels, soft magnetic composites (SMCs), and cobalt-based alloys, on the performance of magnetic gear systems. Literature-based comparative analyses are structured around topological classifications, evaluation of material properties, and performance analyses based on losses. Additionally, the study highlights that aligning material properties with appropriate manufacturing methods, such as powder metallurgy, wire electrical discharge machining (EDM), and precision casting, is essential for the practical scalability of magnetic gear systems. The findings reveal that coaxial magnetic gears (CMGs) offer a favorable balance between high torque density and compactness, while soft magnetic composites provide significant advantages in loss reduction, particularly at high frequencies. Additionally, application trends in fields such as renewable energy, electric vehicles (EVs), aerospace, and robotics are highlighted.
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Research context
OpenAlex topics: Electric Motor Design and Analysis · Magnetic Bearings and Levitation Dynamics · Magnetic Properties and Applications
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Department of Electric and Energy, Kocaeli University, Kocaeli 41001, Turkey
Department of Energy Systems Engineering, Kocaeli University, Kocaeli 41001, Turkey
Department of Machinery and Metal Technologies, Kocaeli University, Kocaeli 41001, Turkey
Department of Electronics and Automation, Ankara University, Ankara 06920, Turkey
Funding
Scientific Research Projects (BAP) Coordination Unit of Kocaeli University under the priority area
References (100+)
Show source-provided references
1. Tlali, P.M., Wang, R.-J., and Gerber, S. (2014, January 2–5). Magnetic gear technologies: A review. Proceedings of the 2014 International Conference on Electrical Machines (ICEM), Berlin, Germany.10.1109/ICELMACH.2014.6960233 ↗
2. Scheidler, J.J. (2018, January 12–14). NASA’s Magnetic gearing research for electrified aircraft propulsion. Proceedings of the 2018 AIAA/IEEE Electric Aircraft Technologies Symposium, Cincinnati, OH, USA.10.2514/6.2018-4988 ↗
3. Measurement and torque calculation of magnetic spur gear based on quasi 3D analytical method
4. A novel high-performance magnetic gear10.1109/20.951324 ↗
5. Calculation of torque performance of a novel magnetic planetary gear10.1109/LMAG.2016.2564948 ↗
6. Torque ripple suppression in an external meshed magnetic gear10.1155/2013/178909 ↗
7. Review and analysis of coaxial magnetic gear pole pair count selection effects10.1109/JESTPE.2021.3053544 ↗
8. Asnani, V., Scheidler, J., and Tallerico, T. (2018, January 14–17). Magnetic gearing research at NASA. Proceedings of the AHS International 74th Annual Forum, Phoenix, AZ, USA.
9. Tallerico, T.F., Cameron, Z.A., Scheidler, J.J., and Hasseeb, H. (2020, January 26–28). Outer stator magnetically-geared motors for electrified urban air mobility vehicles. Proceedings of the AIAA/IEEE Electric Aircraft Technologies Symposium (EATS), New Orleans, LA, USA.10.2514/6.2020-3563 ↗
10. Design, fabrication, test, and benchmark of a magnetically geared permanent magnet generator for wind power generation10.1109/TEC.2019.2951998 ↗
11. Asymptotic analysis of the mathematical model of a wind-powered vehicle10.1016/j.apm.2016.06.022 ↗
12. Design, construction, and analysis of a large-scale inner stator radial flux magnetically geared generator for wave energy conversion10.1109/TIA.2018.2828383 ↗
13. Frandsen, T.V., Rasmussen, P.O., and Jensen, K.K. (2012, January 15–20). Improved motor integrated permanent magnet gear for traction applications. Proceedings of the IEEE Energy Conversion Congress and Exposition (ECCE), Raleigh, CA, USA.10.1109/ECCE.2012.6342334 ↗
14. Esnoz-Larraya, J., Valiente-Blanco, I., Cristache, C., Sanchez-Garcia-Casarrubios, J., Rodriguez-Celis, F., Diez-Jimenez, E., and Perez-Diaz, J.L. (2017, January 20–22). OPTIMAGDRIVE: High-performance magnetic gears development for space applications. Proceedings of the European Space Mechanisms and Tribology Symposium (ESMATS), Hatfield, UK.
15. Frandsen, T.V., and Rasmussen, P.O. (2015, January 24–26). Slip torque investigation and magnetic redesign of motor integrated permanent magnet gear. Proceedings of the 18th International Conference on Electrical Machines and Systems (ICEMS), Pattaya, Thailand.10.1109/ICEMS.2015.7385168 ↗
16. Magnetic gear pole-slip prevention using explicit model predictive control10.1109/TMECH.2012.2207909 ↗
17. Fodorean, D. (2016). State of the art of magnetic gears, their design and characteristics with respect to EV application. Modelling and Simulation for Electric Vehicle Applications, IntechOpen.10.5772/64174 ↗
18. Ikuta, K., Makita, S., and Arimoto, S. (February, January 30). Non-contact magnetic gear for micro transmission mechanism. Proceedings of the IEEE Micro Electro Mechanical Systems, Nara, Japan.
19. Din, G. (2009). A Performance test Design Method and Its Implementation Pattern for Multi-Services Systems. [Ph.D. Thesis, Technical University of Berlin, Department of Electrical Engineering].
20. Comparison of radial force at modulating pieces in coaxial magnetic gear and magnetic geared machine
21. Tapia, M., Jara, R., and Wallace, A. (2018, January 3–6). Parameters identification of an axial flux induction machine using field equations. Proceedings of the XIII International Conference on Electrical Machines (ICEM), Alexandroupoli, Greece.10.1109/ICELMACH.2018.8506891 ↗
22. The radial magnetic coupling studies of perpendicular magnetic gears10.1109/20.539490 ↗
23. Analysis of a magnetic screw for high force density linear electromagnetic actuators10.1109/TMAG.2011.2157464 ↗
24. Development of a magnetic planetary gearbox10.1109/TMAG.2007.914665 ↗
25. The cycloid permanent magnetic gear10.1109/TIA.2008.2006295 ↗
26. A Dual-stack coaxial magnetic gear for wave energy conversion generator10.1109/TMAG.2022.3199580 ↗
27. A novel magnetic harmonic gear10.1109/TIA.2009.2036507 ↗
28. Jing, L., Wang, Y., Li, D., and Qu, R. (2023). Characteristic analysis of a new structure eccentric harmonic magnetic gear. Actuators, 12.10.3390/act12060248 ↗
29. Pakdelian, S., Frank, N.W., and Toliyat, H.A. (2012, January 15–20). Analysis and design of the trans-rotary magnetic gear. Proceedings of the IEEE Energy Conversion Congress and Exposition (ECCE), Raleigh, CA, USA.10.1109/ECCE.2012.6342333 ↗
30. Design, analysis and realisation of a high-performance magnetic gear10.1049/ip-epa:20040224 ↗
31. Development of a high-performance magnetic gear10.1109/TIA.2005.847319 ↗
32. Uppalapati, K., and Bird, J. (2012, January 27–29). A flux focusing ferrite magnetic gear. Proceedings of the 6th IET International Conference on Power Electronics, Machines and Drives, Bristol, UK.10.1049/cp.2012.0303 ↗
33. Analysis of the concentric planetary magnetic gear with strengthened stator and interior permanent magnet inner rotor10.1109/TIA.2011.2154291 ↗
34. Aiso, K., and Akatsu, K. (2016, January 18–22). A novel reluctance magnetic gear for high speed motor. Proceedings of the IEEE Energy Conversion Congress and Exposition, Milwaukee, WI, USA.10.1109/ECCE.2016.7854742 ↗
35. Aiso, K., Akatsu, K., and Aoyama, Y. (2017, January 1–5). Reluctance magnetic gear and flux switching magnetic gear for high speed motor system. Proceedings of the 2017 IEEE Energy Conversion Congress and Exposition (ECCE), Cincinnati, OH, USA.10.1109/IEMDC.2017.8002311 ↗
36. 3-D printing-based design of axial flux magnetic gear for high torque density10.1109/TMAG.2015.2435817 ↗
37. A novel magnetic gear: Toward a higher torque density10.1109/TMAG.2015.2436058 ↗
38. A novel triple-permanent-magnet-excited hybrid-flux magnetic gear and its design method using 3-D finite element method
39. Simulation of a tubular linear magnetic gear using HTS bulks for field modulation10.1109/TASC.2010.2080255 ↗
40. Design and characteristics of a new magnetic worm gear using permanent magnet10.1109/20.280916 ↗
41. Campbell, P. (1994). Permanent Magnet Materials and Their Applications, Cambridge University Press.10.1017/CBO9780511623073 ↗
42. Fast and efficient simulation of the dynamical response of coaxial magnetic gears through direct analytical torque modelling10.1016/j.simpat.2022.102699 ↗
43. Marinova, I., and Mateev, V. (2019, January 15–19). Modeling of dynamic torque control of a coaxial magnetic gear. Proceedings of the 2019 22nd International Conference on the Computation of Electromagnetic Fields (COMPUMAG), Paris, France.10.1109/COMPUMAG45669.2019.9032786 ↗
44. Torque analysis in coaxial magnetic gears considering nonlinear magnetic properties and spatial harmonics10.1109/TMAG.2018.2885729 ↗
45. Natural frequencies and vibrating modes for a magnetic planetary gear drive10.1155/2012/614134 ↗
46. A magnetic gearbox with an active region torque density of 239 Nm/L10.1109/TIA.2017.2779418 ↗
47. Wong, H.Y., Baninajar, H., Dechant, B., and Bird, J. (2020, January 11–15). Designing a magnetic gear for an electric aircraft drivetrain. Proceedings of the 2020 IEEE Energy Conversion Congress and Exposition (ECCE), Detroit, MI, USA.10.1109/ECCE44975.2020.9235977 ↗
48. Analysis and testing of a coaxial magnetic gearbox with flux concentration Halbach rotors10.1109/TMAG.2017.2715799 ↗
49. Optimal design of an outer-stator magnetically geared permanent magnet machine10.1109/TMAG.2015.2487886 ↗
50. Mateev, V., Todorova, M., and Marinova, I. (2023). Design aspects of conical coaxial magnetic gears. Energies, 16.10.3390/en16104191 ↗
51. Analytic expression of magnetic field distribution of rectangular permanent magnets
52. Design and optimization of Halbach magnetic gear10.23967/j.rimni.2024.02.001 ↗
53. Tzouganakis, P., Gakos, V., Kalligeros, C., Papalexis, C., Tsolakis, A., and Spitas, V. (2024). Torque calculation and dynamical response in Halbach array coaxial magnetic gears through a novel analytical 2D model. Computation, 12.10.3390/computation12050088 ↗
54. A coaxial magnetic gear with Halbach permanent-magnet arrays10.1109/TEC.2010.2046997 ↗
55. Two-dimensional analytical investigation of the parameters and the effects of magnetisation patterns on the performance of coaxial magnetic gears10.1049/iet-est.2016.0070 ↗
56. Calculation of torque and loss of coaxial magnetic gear with Halbach array in 3D model10.1007/s42835-021-00964-6 ↗
57. Design comparison of NdFeB and ferrite radial flux surface permanent magnet coaxial magnetic gears10.1109/TIA.2017.2765301 ↗
58. Basak, A. (1996). Permanent Magnet DC Linear Motors, Clarendon Press.10.1093/oso/9780198593928.001.0001 ↗
59. Cost-effectiveness comparison of coaxial magnetic gears with different magnet materials10.1109/TMAG.2013.2281988 ↗
60. Loss analysis of magnetic gear with slotted in magnetic modulation ring10.30941/CESTEMS.2023.00001 ↗
61. Mateev, V., Ivanov, G., and Marinova, I. (2019, January 6–8). Modeling of fluid flow cooling of high-speed rotational electrical devices. Proceedings of the XVI-th International Conference on Electrical Machines, Drives and Power Systems (ELMA), Varna, Bulgaria.10.1109/ELMA.2019.8771637 ↗
62. Mai, Q., Hu, Q., and Chen, X. (2025). Electromagnetic–structural coupling analysis and optimization of bridge-connected modulators in coaxial magnetic gears. Energies, 18.10.3390/en18082069 ↗
63. Desvaux, M., Bildstein, H., Multon, B., Ben Ahmed, H., Sire, S., Fasquelle, A., and Laloy, T. (2018, January 10–12). Magnetic losses and thermal analysis in a magnetic gear for wind turbine. Proceedings of the 2018 Thirteenth International Conference on Ecological Vehicles and Renewable Energies (EVER), Monte-Carlo, Monaco.10.1109/EVER.2018.8362382 ↗
64. Design and analysis of coaxial magnetic gears considering rotor losses10.1109/TMAG.2015.2435253 ↗
65. An analytical model for the computation of no-load eddy current losses in the rotor of a permanent magnet synchronous machine
66. Estimating rotational iron losses in an induction machine10.1109/TMAG.2003.819451 ↗
67. Nikolarea, N., Tzouganakis, P., Gakos, V., Papalexis, C., Tsolakis, A., and Spitas, V. (2024). Detailed investigation of the eddy current and core losses in coaxial magnetic gears through a two-dimensional analytical model. Math. Comput. Appl., 29.10.3390/mca29030038 ↗
68. Core loss analysis of permanent magnet linear synchronous generator considering the 3-D flux path10.1109/TMAG.2017.2751076 ↗
69. Impact of modulator designs and materials on efficiency and losses in radial passive magnetic gear10.1109/TEC.2018.2862462 ↗
70. Preliminary analysis of eddy current and iron loss in magnetic gear in electric vehicle
71. Analytical prediction of the flux reversal permanent magnet machine with Halbach array magnets in rotor slot considering saturation10.1049/rpg2.12452 ↗
72. Ouamara, D., and Dubas, F. (2019). Permanent-magnet eddy-current losses: A global revision of calculation and analysis. Math. Comput. Appl., 24.10.3390/mca24030067 ↗
73. Elgamli, E., and Anayi, F. (2023). Advancements in electrical steels: A comprehensive review of microstructure, loss analysis, magnetic properties, alloying elements, and the influence of coatings. Appl. Sci., 13.10.3390/app131810283 ↗
74. Rotor eddy-current loss in permanent magnet brushless machines10.1109/TMAG.2004.832481 ↗
75. Effect of axial segmentation of permanent magnets on rotor loss in modular permanent-magnet brushless machines10.1109/TIA.2007.904397 ↗
76. Mirzaei, M., Binder, A., and Deak, C. (2010, January 6–8). 3D analysis of circumferential and axial segmentation effect on magnet eddy-current losses in permanent magnet synchronous machines with concentrated windings. Proceedings of the XIX International Conference on Electrical Machines, Rome, Italy.10.1109/ICELMACH.2010.5608182 ↗
77. Vannest, J., and Zhang, J. (2025). Partially segmented permanent-magnet losses in interior permanent-magnet motors. Energies, 18.10.3390/en18112879 ↗
78. Quantitative comparative analysis of radial flux, transverse flux, and axial flux magnetic gears10.1109/TMAG.2014.2327622 ↗
79. (2025, June 13). Magweb. Available online: https://www.magweb.us/smag/.
80. Paltanea, G., Manescu, V., Antoniac, A., Nemoianu, I.V., and Gavrila, H. (2024). Mechanical and Magnetic Properties Variation in Non-Oriented Electrical Steels with Different Cutting Technology: A Review. Materials, 17.10.3390/ma17061345 ↗
81. Syreyshchikova, N.V., Guzeev, V.I., Ardashev, D.V., Pimenov, D.Y., Patra, K., Kapłonek, W., and Nadolny, K. (2020). A study on the machinability of steels and alloys to develop recommendations for setting tool performance characteristics and belt grinding modes. Materials, 13.10.3390/ma13183978 ↗
82. Machinability of Cobalt-based and Cobalt Chromium Molybdenum Alloys—A Review10.1016/j.promfg.2017.07.150 ↗
83. Comparison study on SMC and grain-oriented laminated steel core for small-size axial flux permanent-magnet synchronous machines10.1088/2053-1591/ad8413 ↗
84. Sarala Rubi, C., Prakash, J.U., Juliyana, S.J., Čep, R., Salunkhe, S., Kouril, K., and Ramdas Gawade, S. (2024). Comprehensive review on wire electrical discharge machining: A non-traditional material removal process. Front. Mech. Eng., 10.10.3389/fmech.2024.1322605 ↗
85. New Soft Magnetic Composites for electromagnetic applications with improved mechanical properties10.1063/1.4943413 ↗
86. Structure and magnetic properties of vacuum- and air-annealed rapidly quenched Mo- and Co-modified Fe85.3Cu0.7B14 alloy10.1007/s43452-025-01238-y ↗
87. Müller, M., Czempas, D., Bailly, D., and Hirt, G. (2021). Twin Roll Casting and Secondary Cooling of 6.0 wt.% Silicon Steel. Metals, 11.10.3390/met11101508 ↗
88. Soft magnetic composite materials (SMCs)10.1016/j.jmatprotec.2007.02.034 ↗
89. Dougan, M.J. (2018, January 2). Powder metallurgical materials and processes for soft magnetic applications. Proceedings of the Workshop SRM Drives an Alternative for E-Traction, Vilanova i La Geltrú (Barcelona), Spain.
90. Filippini, M., Alotto, P., Cirimele, V., Repetto, M., Ragusa, C., Dimauro, L., and Bonisoli, E. (2019). Magnetic loss analysis in coaxial magnetic gears. Electronics, 8.10.3390/electronics8111320 ↗
91. Electromagnetic analysis of linear magnetic gears based on the characteristics of their flux-modulation poles10.1109/TASC.2020.2966153 ↗
92. Magnetic properties of soft magnetic composite using external flux impression method
93. A coaxial magnetic gear with consequent-pole rotors10.1109/TEC.2016.2609338 ↗
94. Reduction of core size and power losses of a soft composite magnetic gear10.1016/j.simpat.2025.103135 ↗
95. Cros, J., Viarouge, P., and Halila, A. (2001, January 22). Brush DC motors with concentrated windings and soft magnetic composites armatures. Proceedings of the IEEE International Applications Conference, Chicago, IL, USA.
96. Guo, Y., Zhu, J., Zhong, J., and Wu, W. (2002, January 13–18). Comparative study of 3D flux electrical machines with soft magnetic composite cores. Proceedings of the IEEE Industry Applications Conference, Pittsburgh, PA, USA.
97. Zhu, J., and Guo, Y. (2004, January 3–7). Study with magnetic property measurement of soft magnetic composite material and its application in electrical machines. Proceedings of the IEEE Industry Applications Conference, Seattle, WA, USA.
98. Development of super low iron-loss P/M soft magnetic material
99. Hultman, L.O., and Jack, A.G. (2003, January 1–4). Soft magnetic composites—Materials and applications. Proceedings of the IEEE International Electric Machines and Drives Conference (IEMDC’03), Madison, WI, USA.10.1109/IEMDC.2003.1211312 ↗
100. Ruiz-Ponce, G., Arjona, M.A., Hernandez, C., and Escarela-Perez, R. (2023). A review of magnetic gear technologies used in mechanical power transmission. Energies, 16.10.3390/en16041721 ↗