Design optimization of coreless stator axial flux-switching motor

Document Type : Article


Department of Electrical Engineering, Technical and Vocational University (TVU), Tehran, P.O. Box 14357-61137, Iran


This study aimed to provide the analytical design, optimization, and three-dimensional (3D) simulation through finite element method of a coreless stator axial field flux-switching motor (AFFSM). The motor consists of two indented rotors with a coreless stator between them consisting of a magnet and winding. First of the motor electrical and magnetic design was performed and its basic parameters were calculated. Then, the optimization of the machine was evaluated implementing the Taguchi algorithm in order to minimize the motor cogging torque. Some of the basic motor dimensions, such as the magnet length and width, the rotor tooth width and height, and the back iron thickness, were selected as optimization variables, and the best combination of these variables was obtained by changing them in a certain range to achieve the desired objective. Then, the accuracy of analytical design and optimization was evaluated through forming a 3D finite element method (FEM) of the motor and investigating its performance. Comparison of the optimized and primary motor revealed that the optimal design had a better performance than the initial. Finally, a prototype of the proposed motor was fabricated and tested, which indicated that the experimental results were largely similar to the analytical results.


1. Jilong, Z., Xiaowei, Q., Xiangdong, S., et al. "Design of a novel axial flux rotor consequent-pole permanent magnet machine", IEEE Trans. Appl. Supercond., 30(4), pp. 1-6 (2020).
2. Jian, L., Yang, L., Yun-Hyun, C., et al. "Design, analysis, and prototyping of a water-cooled axial-flux permanent-magnet machine for large-power directdriven applications", IEEE Trans. Ind. Appl., 55(4), pp. 3555-3565 (2019).
3. Youhua, W., Jiawei, L., Chengcheng, L., et al. "Development of a high-performance axial flux PM machine with SMC cores for electric vehicle application", IEEE Trans. Magn., 55(7), pp. 1-4 (2019).
4. Jilong, Z., Xiaowei, Q., and Mingyao, L. "Model predictive torque control of a hybrid excited axial field flux-switching permanent magnet machine", IEEE Access, 8, pp. 33703-33712 (2020).
5. Wei, Z., Zexian, Y., Liangguan, Z., et al. "Speed sensorless control of hybrid excitation axial field flux switching permanent-magnet machine based on model reference adaptive system", IEEE Access, 8, pp. 22013-22024 (2020).
6. Kostas, L., Alexandros, M., Ilias, K., et al. "Acoustic noise  of axial flux permanent magnet generators in locally manufactured small wind turbines", IET Renew. Power Gener., 13(15), pp. 2922-2928 (2019).
7. Nasrudin, A.R., Hew Wooi, P., and Mohammad Faridun Naim, T. "Design of an in-wheel axial flux brushless DC motor for electric vehicle", In 2006 International Forum on Strategic Technology, pp. 16- 19 (2006).
8. Wasiq, U., Faisal, K., Erwan, S., et al. "Torque characteristics of high torque density partitioned PM consequent pole flux switching machines with flux barriers", CES Trans. Electr. Mach. Syst., 4(2), pp. 130-141 (2020).
9. Ju Hyung, K., Yingjie, L., and Bulent, S. "Sizing, analysis, and verification of axial flux-switching permanent magnet machine", IEEE Trans. Ind. Appl., 55(4), pp.  3512-3521 (2019).
10. Ju Hyung, K., Yingjie, L., Emrah, C., et al. "Influence of rotor tooth shaping on cogging torque of axial flux switching permanent magnet machine", IEEE Trans. Ind. Appl., 55(2), pp. 1290-1298 (2018).
11. Ranjit, K.R., A Rimer on the Taguchi Method, Society of Manufacturing Engineers (2010).
12. Chang-Chou, H., San-Shan, H., Cheng-Tsung, L., et al. "Optimal design of a high speed SPM motor for machine tool applications", IEEE Trans. Magn., 50(1), pp. 1-4 (2013).
13. Teck-Seng, L., Shixin, C., and Xianke, G. "Robust torque optimization for BLDC spindle motors", IEEE Trans. Ind. Electron., 48(3), pp. 656-663 (2001).
14. Huimin, W., Shu, L., Shuang, W., et al. "Optimal design of permanent magnet structure to reduce unbalanced magnetic pull in surface-mounted permanentmagnet motors", IEEE Access, 8, pp. 77811-77819 (2020).
15. Sujin, L., Kyuseob, K., Sugil, C., et al. "Optimal design of interior permanent magnet synchronous motor considering the manufacturing tolerances using Taguchi robust design", IET Electr. Power Appl., 8(1), pp. 23-28 (2014).
16. Albert Johan, S., Rong-Jie, W., and Andries, J.G. "Multiobjective design of a line-start PM motor using the Taguchi method", IEEE Trans. Ind. Appl., 54(5), pp. 4167-4176 (2018).
17. Yen-Shin, L., Juo-Chiun, L., and Jennshing Jersey, W. "Direct torque control induction motor drives with selfcommissioning based on Taguchi methodology", IEEE Trans. Power Electron., 15(6), pp. 1065-1071 (2000).
18. Wenju, Y., Hao, C., Xuekun, L., et al. "Design and multi-objective optimisation of switched reluctance machine with iron loss", IET Electr. Power Appl., 13(4), pp. 435-444 (2019).
19. Ji, Z., Li, H., Chen. Z., et al. "Design and optimization of permanent magnet assisted synchronous reluctance motor for better torque performance", In 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), pp. 1-4 (2019).
20. Wenshuai, Z., Xuzhen. H., and Tianpeng, J. "Design of tubular permanent magnet synchronous linear motor in a wide temperature range environment by Taguchifuzzy method", In 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), pp. 1-5 (2019).
21. Juncai, S., Fei, D., Jiwen, Z., et al. "Optimal design of permanent magnet linear synchronous motors based on Taguchi method", IET Electr. Power Appl., 11(1), pp. 41-48 (2017).
22. Hyung Jin, S., Rod, B., Zhongyi, G., et al. "Design of a 12-MW HTS wind power generator including a flux pump exciter", IEEE Trans. Appl. Supercond., 26(3), pp. 1-5 (2016).
23. Surong, H., Jian, L., Franco, L., et al. "A comparison of power density for axial flux machines based on general purpose sizing equations", IEEE Trans. Energy Convers., 14(2), pp. 185-192 (1999).
24. Jacek, F.G., Rong-Jie, W., and Maarten, J.K., Axial Flux Permanent Magnet Brushless Machines, Springer Science & Business Media (2008).
25. Maarten, J.K., Rong-Jie, W., and Francois, G.R. "Analysis and performance evaluation of axial flux air-cored stator permanent magnet machine with concentrated coils", In 2007 IEEE International Electric Machines & Drives Conference, 1, pp. 13-20 (2007).
26. Kostas, L., Katerina, T., Thomas. P., et al. "Design of axial flux permanent magnet generators using various magnetic materials in locally manufactured small wind turbines", In 2016 XXII International Conference on Electrical Machines (ICEM), pp. 1545-1551 (2016).
27. Maarten, J.K., Rong-Jie, W., and Francois, G.R. "Analysis and performance of axial flux permanentmagnet machine with air-cored nonoverlapping concentrated stator windings", IEEE Trans. Ind. Appl., 44(5), pp. 1495-1504 (2008).
28. Zhu, Z.Q. "A simple method for measuring cogging torque in permanent magnet machines", In 2009 IEEE Power & Energy Society General Meeting, pp. 1-4 (2009).