Improved V?shaped interior permanent magnet rotor topology with inward?extended bridges for reduced torque ripple

Gao, Peng; Sun, Xibin; Gerada, David; Gerada, Chris; Wang, Xiaoyuan

Abstract

Interior permanent magnet synchronous machines (IPMSMs) with V-shaped permanent magnet (PM) rotors are widely used as traction motors in electric vehicles because of their high torque density and high efficiency. However, the V-shape IPMSMs have the disadvantages of inevitable torque ripple due to the non-sinusoidal air-gap flux density distribution and the utilisation of the reluctance torque. In this study, with the aim of improving the torque ripple characteristics, a modified V-shaped IPMSM rotor configuration with bridges extended inwards towards the pole centre is proposed to generate a more sinusoidal air-gap flux density waveform. The proposed topology, referred to as ‘Type C’ within this study, is compared with baseline rotor configuration references, namely ‘Type A’ which is a conventional V-shaped PM rotor, as well as ‘Type B’ which is a related configuration with a mechanically non-uniform air gap. The analysis results show that the rotor ‘Type C’ exhibits significant advantages in terms of reducing cogging torque, torque ripple and radial force, without incurring additional air-gap friction losses. Finally, a prototype of the IPMSM with the proposed rotor configuration is manufactured and tested, verifying the predicted benefits experimentally.

• Journal Article Type: Article
• Acceptance Date: Aug 18, 2020
• Online Publication Date: Sep 17, 2020
• Publication Date: 2020-12
• Deposit Date: Feb 26, 2021
• Publicly Available Date: Feb 26, 2021
• Journal: IET Electric Power Applications
• Print ISSN: 1751-8660
• Electronic ISSN: 1751-8679
• Publisher: Institution of Engineering and Technology (IET)
• Peer Reviewed: Peer Reviewed
• Volume: 14
• Issue: 12
• Pages: 2404-2411
• DOI: https://doi.org/10.1049/iet-epa.2019.0850
• Keywords: electric vehicles; torque; synchronous machines; traction motors; permanent magnet motors; air gaps; rotors
• Public URL: https://nottingham-repository.worktribe.com/output/5234653
• Publisher URL: https://ietresearch.onlinelibrary.wiley.com/doi/10.1049/iet-epa.2019.0850
• Additional Information: Gao, P., Sun, X., Gerada, D., Gerada, C., & Wang, X. (2020). Improved V‐shaped interior permanent magnet rotor topology with inward‐extended bridges for reduced torque ripple. IET Electric Power Applications, 14(12), 2404–2411. https://doi.org/10.1049/iet-epa.2019.0850