Comparing different configurations for rotary transformer of wound-rotor resolvers

Document Type : Article


1 School of Advanced Technologies, Iran University of Science and Technology (IUST), Tehran, Iran

2 Electrical Engineering Department, Iran University of Science and Technology (IUST), Tehran, Iran


Wound-Rotor resolvers are the oldest and the most widely used resolvers. They are two-phase synchronous generators with high frequency AC excitation. Rotary Transformers (RTs) are used to supply the rotating excitation winding of the resolver. Although RTs offer the benefits of contactless power transmission, harmonic contents of the secondary voltage, phase shift error between the primary and the secondary voltages, and high leakage flux are the main challenges in their usage along with resolvers. Therefore, in this paper, different configurations are examined for RT’s ferromagnetic core to overcome the mentioned problems. All the simulations are done using 3-D time variant finite element method (TVFEM) and the best configuration is chosen for experimental prototyping and measurements. Close agreement between the simulation and the experimental test results approves the performed analysis.


1. Mohammad-Yari, M., Safari, M., Alipour-Sarabi, R., et al. "Optimal winding selection for wound-rotor resolvers", Scientia Iranica, 28(6), pp. 3429-3436 (2021). DOI: 10.24200/sci.2019.52439.2764, early access 
2. Lasjerdi, H. and Nasiri-Gheidari, Z. "A comprehensive analysis of short-circuit fault in woundrotor resolvers", IEEE Transactions on Vehicular Technology, 69(12), pp. 14884-14892 (2020). DOI:10.1109/TVT.2020.3043273.
3. Saneie, H., Nasiri-Gheidari, Z., Tootoonchian, F., et al. "Simplified Winding Arrangement for Integrated Multi-Turn Resolvers", IEEE Transactions on Industrial Electronic, 68(12), pp. 12802-12809 (2020).
4. Bahari, M. and Nasiri-Gheidari, Z. "The comparative analysis of AC-flux and DC-flux resolvers", Scientia Iranica, 29(4), pp. 2007-2013 (2022).
5. Tavakoli, S. and Nasiri-Gheidari, Z. "Static eccentricity fault diagnosis in a cylindrical wound-rotor resolver", International Journal of Industrial Electronics Control and Optimization, 3(1), pp. 19-26 (2020). DOI: 10.22111/ieco.2019.28577.1134.
6. Alemi-Rostami, M., Alipour-Sarabi, R., Rezazadeh, G., et al. "Design optimization of a doublestage resolver", IEEE Transactions on Vehicular Technology, 68(6), pp. 5407-5415 (2019). DOI:10.1109/TVT.2019.2909096.
7. Alipour-Sarabi, R., Nasiri-Gheidari, Z., Oraee, H. "Misconception of total harmonic distortion in resolvers", Electromechanical Energy Conversion Systems, 1(1), pp. 38-43 (2019).
8. Gel, X. and Zhu, Z.Q. "A novel design of rotor contour for variable reluctance resolver by injecting auxiliary air-gap permeance harmonics", IEEE Transactions on Energy Conversion, 31(1), pp. 345-353 (2016).
9. Jing, S., Hao, W., and Weiqiang, W. "The analysis of multipole axial flux reluctance resolver with sinusoidal rotor", 2012 IEEE 7th International Power Electronics and Motion Control Conference-ECCE Asia, June 2-5, Harbin, China (2012).
10. Nasiri-Gheidari, Z. "Design analysis, and prototyping of a new wound-rotor axial flux brushless resolver", IEEE Transaction on Energy Conversion, 32(1), pp. 276 -283 (2017).
11. Nasiri-Gheidari, Z. "Investigating the effect of the rotary transformer leakage flux on the detected position of axial flux brushless resolvers", Tabriz Journal of Electrical Engineering, 47(2), pp. 741-749 (2017).
12. Abolqasemi Kharanaq, F., Alipour-Sarabi, R., Nasiri-Gheidari, Z., et al. "Magnetic equivalent circuit model for wound rotor resolver without rotary transformer's core", IEEE Sensors J., 18(21), pp. 8693-8700 (2018).
13. Tootoonchian, F., Ardebili, M., and Abbaszadeh, K. "Using average DC-pulse response of stator current for identification of single-phase rotary transformer parameters", Przegl d Elektrotechniczny, 88(11a), pp. 142-146 (2012).
14. Ruviaro M. and Runcos F. "A brushless doubly fed induction machine with at plane rotary transformers", 2012 XXth International Conference on Electrical Machines, Marseille, pp. 23-29 (2012). DOI:10.1109/ICElMach.2012.6349832.
15. Ruviaro, M., Runcos, F., Sadowski, N. et al. "Design and analysis of a brushless doubly fed induction machine with rotary transformer", The XIX International Conference on Electrical Machines-ICEM 2010, Rome, pp. 1-6 (2010). DOI:10.1109/ICELMACH.2010.5607735.
16. Ditze, S., Endruschat, A., Schriefer, T., et al. "Inductive power transfer system with a rotary transformer for contactless energy transfer on rotating applications", 2016 IEEE International Symposium on Circuits and Systems (ISCAS), Montreal, QC, pp. 1622-1625 (2016). DOI:10.1109/ISCAS.2016.7538876.
17. Stancu, C., Ward, T., Rahman, K.M., et al. "Separately excited synchronous motor with rotary transformer for hybrid vehicle application", IEEE Transactions on Industry Applications, 54(1), pp. 223-232 (2018).
18. Duan, J., Lina, B., Yang, Q., et al. "Design and testing of a novel rotary transformer for rotary ultrasonic machining", IEICE Electronics Express, 14(23) (2017).
19. Weber, J., Rehfeldt, A., Vip, S., et al. "Rotary transformer with electrical steel core for brushless excitation of synchronous machines", 2016 XXII International Conference on Electrical Machines (ICEM), Lausanne, 2016, pp. 884-889 (2016). DOI:10.1109/ICELMACH.2016.7732630.
20. Haruna, J. and Raminosoa, T. "Modeling and steadystate analysis of a rotary transformer-based field excitation system for wound rotor synchronous machine", 2019 IEEE Transportation Electrification Conference and Expo (ITEC), Detroit, MI, USA, pp. 1-8 (2019). DOI:10.1109/ITEC.2019.8790472.