Effect of Multilayer Windings with Different Stator Winding Connections on Interior PM Machines for EV Applications

Ayman Samy Abdel-Khalik*, Shehab Ahmed, Ahmed M. Massoud

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

76 Scopus citations


The interior permanent magnet (IPM) machine equipped with a fractional-slot concentrated winding (FSCW) has met an increasing interest in electric vehicle applications due to its higher power density and efficiency. Torque production is due to both PM and reluctance torques. However, one of the main challenges of FSCWs is their inability to produce a high-quality magnetomotive force (MMF) distribution, yielding undesirable rotor core and magnet eddy-current losses. Literature shows that the reduction of low-order space harmonics significantly reduces these loss components. Moreover, it has been previously shown that by employing a higher number of layers, although causing some reduction in the winding factor of the torque-producing MMF component, both machine saliency and reluctance torque components are improved. Recently, a dual three-phase winding connected in a star/delta connection has also shown promise to concurrently enhance machine torque of a surface-mounted PM machine while significantly reducing both rotor core and magnet losses. In this paper, a multilayer winding configuration and a dual three-phase winding connection are combined and applied to the well-known 12-slot/10-pole IPM machine with v-shaped magnets. The proposed winding layout is compared with a conventional double-layer winding, a dual three-phase double-layer winding, and a four-layer winding. The comparison is carried out using 2-D finite-element analysis. The comparison shows that the proposed winding layout, while providing similar output torque to a conventional double-layer three-phase winding, offers a significant reduction in core and magnet losses, correspondingly a higher efficiency, improves the machine saliency ratio, and maximizes the reluctance toque component.

Original languageEnglish (US)
Article number7308067
JournalIEEE Transactions on Magnetics
Issue number2
StatePublished - Feb 2016
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 1965-2012 IEEE.


  • combined star/delta connection
  • double layer winding
  • eddy current losses
  • Fractional slot concentrated winding
  • interior permanent magnet
  • multilayer winding
  • rotor iron losses

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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