Abstract
The limited availability and high cost of permanent magnet (PM) materials have drawn the attention of researchers toward PM-free and hybrid machines. Brushless wound rotor synchronous machines (BLWRSMs) have gained significant popularity among these machines. These machines require less maintenance because they do not use carbon brushes, slip rings, and an external DC source. This work introduces a novel self-excited BLWRSM configuration based on a dual harmonic winding (HW). Unlike the existing BLWRSM design using a single HW, the proposed configuration effectively utilizes the unused space within the rotor slots of the existing model. It introduces an additional HW on the rotor to carry alternating current induced by the inherent subharmonic component generated within the stator magnetomotive force. A series capacitor is added to the dual HWs to ensure their currents are in phase. The alternating current of dual HW is rectified via a rotor-mounted rectifier to supply the required direct current excitation to the rotor field winding for the generation of rotor magnetic field. The addition of extra HW contributes to an increased field current, which significantly improves the torque features of the proposed motor. Finite element analysis is used to verify the proposed design in JMAG-Designer version 18.1 software. The obtained results demonstrate that, when both machines operate with the same magnitude of stator winding current, the machine being proposed exhibits a 22.15% improvement in average torque in comparison with the existing model, making it a potential substitute for high-torque applications.
Data availability
All necessary data are included within the manuscript.
References
Lipo, T. A. & Du, Z. S. In Intl Aegean Conference on Electrical Machines & Power Electronics (ACEMP), 2015 Intl Conference on Optimization of Electrical & Electronic Equipment (OPTIM) & 2015 Intl Symposium on Advanced Electromechanical Motion Systems (ELECTROMOTION). 1–5 (IEEE). 1–5 (IEEE). (2015).
De Santiago, J. et al. Electrical motor drivelines in commercial all-electric vehicles: A review. IEEE Trans. Veh. Technol. 61, 475–484 (2011).
Dorrell, D. G. In IECON 2012-38th Annual Conference on IEEE Industrial Electronics Society. 4880–4885 (IEEE).
Kumar, K. et al. Performance improvement of brushless wound rotor Vernier motor for washing machine applications. IEEE Access (2025).
Fayyaz, A., Mehmood, F., Waheed, A., Ullah, Z. & C. M. & Novel winding design and analysis of brushless wound rotor synchronous machines. IET Electr. Power Appl. 19, e70019 (2025).
Bukhari, S. S. H. & Rasilo, P. High-Efficient Self-Excited brushless wound rotor synchronous machine topology. IEEE Trans. Magnetics (2025).
Yao, F., An, Q., Gao, X., Sun, L. & Lipo, T. A. Principle of operation and performance of a synchronous machine employing a new harmonic excitation scheme. IEEE Trans. Ind. Appl. 51, 3890–3898 (2015).
Hussain Bukhari, S. S., Yu, J., Shah, M. A., Bajaj, M. & Ro, J. S. Brushless Wound Rotor Synchronous Machine Based on a Consequent-Pole Rotor Structure with Better Torque Attributes. Inter. Trans. Electr. Energy Syst. (2022).
Jawad, G., Ali, Q., Lipo, T. A. & Kwon, B. I. Novel brushless wound rotor synchronous machine with zero-sequence third-harmonic field excitation. IEEE Trans. Magn. 52, 1–4 (2016).
Bukhari, S. S. H., Ahmad, H., Sirewal, G. J. & Ro, J. S. Simplified brushless wound field synchronous machine topology based on a three-phase rectifier. IEEE Access. 9, 8637–8648 (2021).
Chung, J. & Hofmann, H. Brushless Self-Excited synchronous Field-Winding machine with Five-and Higher-Phase design using independently controlled Spatial harmonics. IEEE Trans. Energy Convers. (2023).
Roshanzamir, A. et al. Dual-mode brushless wound rotor synchronous machine for high starting torque. IEEE Access. 10, 41657–41663 (2022).
Sirewal, G. J., Ayub, M., Atiq, S. & Kwon, B. I. Analysis of a brushless wound rotor synchronous machine employing a stator harmonic winding. IEEE Access. 8, 151392–151402 (2020).
Bukhari, S. S. H., Sirewal, G. J., Ayub, M. & Ro, J. S. A new small-scale self-excited wound rotor synchronous motor topology. IEEE Trans. Magn. 57, 1–5 (2020).
Ahmed, S. et al. Brushless wound rotor synchronous machine topology using concentrated winding for dual speed applications. IEEE Access. 11, 119560–119567 (2023).
Ayub, M., Jawad, G. & Kwon, B. -i. Consequent-pole hybrid excitation brushless wound field synchronous machine with fractional slot concentrated winding. IEEE Trans. Magn. 55, 1–5 (2019).
Ayub, M., Bukhari, S. S. H., Jawad, G. & Kwon, B. -i. Brushless wound field synchronous machine with third-harmonic field excitation using a single inverter. Electr. Eng. 101, 165–173 (2019).
Rafin, S. S. H., Ali, Q. & Lipo, T. A. A novel sub-harmonic synchronous machine using three-layer winding topology. World Electr. Veh. J. 13, 16 (2022).
Hussain, A. & Kwon, B. -i. A new brushless wound rotor synchronous machine using a special stator winding arrangement. Electr. Eng. 100, 1797–1804 (2018).
Haq, M. A. U., Farooq, H., Hussain, A. & Kashif, S. A. R. A novel brushless wound rotor synchronous machine utilizing inherent Sub-Harmonic component. IEEE Access (2025).
Haq, M. A. U., Farooq, H., Liaqat, R., Khan, Z. A. & Altamimi, A. A novel permanent magnet assisted brushless wound rotor synchronous machine with improved torque characteristics. IEEE Access (2025).
ul Haq, M. A., Farooq, H., Liaqat, R., Khan, Z. A. & Altamimi, A. A novel self excited hybrid brushless wound rotor synchronous machine with consequent Poles. Sci. Rep. 15, 41069. https://doi.org/10.1038/s41598-025-24914-8 (2025).
Yan, Y., Bukhari, S. S. H. & Ro, J. S. Novel hybrid Consequent-Pole brushless wound rotor synchronous machine for improving torque characteristics. IEEE Access. 10, 35953–35964 (2022).
Acknowledgements
The authors wish to express their gratitude to their parent organizations for providing the research facilities that made this work possible.
Funding
The authors extend the appreciation to the Deanship of Postgraduate Studies and Scientific Research at Majmaah University for funding this research work through the project number (R-2026-2336).
Author information
Authors and Affiliations
Contributions
Conceptualization (M.A.U.H. and H.F.), Software Simulation (M.A.U.H.),Validation (R.L., Z.A.K. and A.A), Writing (M.A.U.H., H.F., and R.L.), Data Curation (M.A.U.H., H.F., R.L., Z.A.K. and A.A.), Review and Editing (M.A.U.H., H.F., R.L., Z.A.K. and A.A.), Visualization (M.A.U.H.,R.L., Z.A.K. and A.A.), Formal Analysis (Z.A.K. and A.A), Supervision (H.F.), Project Funding (A.A.), Resources (M.A.U.H. , H.F. and A.A.). All authors reviewed the final draft and agreed to its contents.
Corresponding authors
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
About this article
Cite this article
ul Haq, M.A., Farooq, H., Liaqat, R. et al. A novel rotor harmonic winding-based high efficient self-excited brushless wound rotor synchronous machine with improved torque features. Sci Rep (2026). https://doi.org/10.1038/s41598-026-38287-z
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-026-38287-z
