Low space harmonics cancelation in double-layer fractional slot winding using dual multiphase winding

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

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

One of the main drawbacks of nonoverlapped coils in fractional slot concentrated winding permanent magnet (PM) machines are the high eddy current losses in both rotor core and permanent magnets induced by the asynchronous harmonics of the armature reaction field. It has been shown in the literature that the reduction of low space harmonics can effectively reduce the rotor eddy current losses. This paper shows that employing a combined star-delta winding to a three-phase PM machine with fractional slot windings and with a number of slots equal to 12, or its multiples, yields a complete cancellation to the fundamental magneto-motive force (MMF) component, which significantly reduces the induced rotor eddy current. Besides, it offers a slight increase in machine torque density. A case study on the well-known 12-slot/10-pole PM machine is conducted to explore the proposed approach. With the same concept, the general n-phase PM machine occupying 4n slots and with a dual n-phase winding is then proposed. This configuration offers a complete cancelation of all harmonics below the torque producing MMF component. Hence, the induced eddy currents in both rotor core and magnets are significantly reduced. The winding connection and the required number of turns for both winding groups are also given. The concept is applied to a 20-slot/18-pole stator with a dual five-phase winding, where the stator winding is connected as a combined star/pentagon connection. The proposed concept is assessed through a simulation study based on 2-D finite element analysis.

Original languageEnglish
Article number6935012
JournalIEEE Transactions on Magnetics
Volume51
Issue number5
DOIs
Publication statusPublished - 1 May 2015

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Keywords

  • Eddy current loss
  • finite element method
  • fractional slot winding
  • loss reduction
  • permanent magnet (PM) machines
  • star/delta connection
  • star/pentagon connection

ASJC Scopus subject areas

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

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