C- and circular-shaped barriers optimization in a synchronous reluctance rotor for torque ripples minimization

Document Type : Article


1 Department of Electrical Engineering, K.N. Toosi University of Technology, Tehran, Iran

2 Electrical Machine Group, Niroo Research Institute (NRI), Tehran, Iran


Due to the lack of magnets and the suitable final price, synchronous reluctance motors are potential applicants for household electric appliances and so on. But in general, they suffer from high torque ripple. Optimized design of the synchronous reluctance rotor structure is presented for two different types of barrier shape with aiming to reduce the torque ripple along with increasing the average torque.
In this paper, the optimization of rotor geometries with a fixed machine size for C-shaped barriers and circular barriers type is investigated. Most of the rotor parameters such as the width of iron parts, and the width of barriers along d and q axis are optimized by a new method using the PSO algorithm. Besides, the angle of end points for each barrier with constant rib and insulation factor are considered in optimization process. Minimizing the torque ripple without losing or even increasing the average torque is the most critical optimization achievement. Two prototypes of the optimized rotor with the C-shaped and circular barriers type have been fabricated and experimentally compared. The results obtained from the 2-D Finite Element Simulation of the recommended machine conform well to the experimental result.


1. Oliveira, F. and Ukil, A. "Energy efficiency in variable speed centrifugal chiller systems driven by synchronous reluctance motors", 2018 IEEE Innovative Smart Grid Technologies - Asia (ISGT Asia), Singapore, pp. 340- 344 (2018).
2. Hofer, M., Nikowitz, M., and Schrodl, M. "Comparative analysis of salient pole and  ux barrier rotor for synchronous reluctance machines including flux weakening range", The Journal of Engineering, 2019(17), pp. 4055-4059 (2019).
3. Salehinia, S.R., Afjei, E., and Hekmati, A. "Analytical method to optimum design of synchronous reluctance motor for  electric scooter application", Scientia Iranica, 29(5), pp. 2537-2551 (2021).
4. Diao, X., Zhu, H., Qin, Y., et al. "Torque ripple minimization for bearingless synchronous reluctance motor", IEEE Transactions on Applied Superconductivity,28(3), pp. 1-5 (2018). 
5. Li, J., Xin, M., Fan, Z., et al. "Design and experimental evaluation of a 12 kW large synchronous reluctance motor and control system for elevator traction", IEEE Access, 8, pp. 34256-34264 (2020).
6. Castagnaro, E., Bacco, G., and Bianchi, N. "Impact of geometry on the rotor iron losses in synchronous reluctance motors", IEEE Transactions on Industry  Applications, 55(6), pp. 5865-5872 (2019).
7. Yan, D., Xia, C., Guo, L., et al. "Design and analysis for torque ripple reduction in synchronous reluctance machine", 2018 IEEE International Magnetics Conference (INTERMAG), Singapore, pp. 1-1 (2018).
8. Chai, W., Zhao, W., and Kwon, B. "Optimal design of wound field synchronous reluctance machines to improve torque by increasing the saliency ratio", IEEE Transactions on Magnetics, 53(11), pp. 1-4 (2017).
9. Staton, D.A., Miller, T.J.E., and Wood, S.E. "Maximising the saliency ratio of the synchronous reluctance motor", IEE Proceedings B - Electric Power Applications, 140(4), pp. 249-259 (1993).
10. Bacco, G. and Bianchi, N. "Design criteria of fluxbarriers in synchronous reluctance machines", IEEE Transactions on Industry Applications, 55(3), pp. 2490-2498 (2019).
11. Bianchi, N., Bolognani, S., Bon, D., et al. "Rotor flux-barrier design for torque ripple reduction in synchronous reluctance and PM-assisted synchronous reluctance motors", IEEE Transactions on Industry Applications, 45(3), pp. 921-928 (2009).
12. Palmieri, M., Cascella, G.L., and Cupertino, F. "Design methodologies for the output power maximisation of synchronous reluctance machines", IET Electric Power Applications, 13(8), pp. 1131-1140 (2019).
13. Mohammadi, M.H., Rahman, T., Silva, R., et al. "A computationally efficient algorithm for rotor design optimization of synchronous reluctance machines", IEEE Transactions on Magnetics, 52(3), pp. 1-4 (2016).
14. Pellegrino, G., Cupertino, F., and Gerada, C. "Automatic design of synchronous reluctance motors focusing on barrier shape optimization", IEEE Transactions on Industry Applications, 51(2), pp. 1465-1474 (2015).
15. Alemi-Rostami, M., Rezazadeh, G., Alipour-Sarabi, R., et al. "Design and optimization of a large-scale permanent magnet synchronous generator", Scientia Iranica, 29(1), pp. 217-229 (2019).
16. Nasiri-Zarandi, R., Ajamloo, A.M., and Abbaszadeh, K. "Design optimization of a transverse  flux halbacharray PM generator for direct drive wind turbines", IEEE Transactions on Energy Conversion, 35(3), pp. 1485-1493 (2020).
17. Howard, E., Kamper, M.J., and Gerber, S. "Asymmetric flux barrier and skew design optimization of reluctance synchronous machines", IEEE Transactions on Industry Applications, 51(5), pp. 3751-3760 (2015).
18. Babetto, C., Bacco, G., and Bianchi, N. "Synchronous reluctance machine optimization for high speed applications", IEEE Transactions on Energy Conversion, 33(3), pp. 1266-1273 (2018).
19. Boztas, G., Aydogmus, O., Caner, M., et al. "Design, optimisation and implementation of low-voltage synchronous reluctance motor for solar-powered systems", IET Power Electronics, 12(7), pp. 1679-1685 (2019).
20. Moghaddam, R.R. "Synchronous reluctance machine SynRM in variable speed drives VSD applications", Ph.D. Dissertation, KTH School of Electrical Engineering (2011).
21. Mahmoud, H., Bacco, G., Degano, M., et al. "Synchronous reluctance motor iron losses: Considering machine nonlinearity at MTPA, FW, and MTPV operating conditions", IEEE Transactions on Energy Conversion, 33(3), pp. 1402-1410 (2018).