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Computationally Efficient Strand Eddy Current Loss Calculation in Electric Machines

Lookup NU author(s): Dr Rafal Wrobel

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This is the authors' accepted manuscript of an article that has been published in its final definitive form by IEEE, 2019.

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Abstract

A fast finite element (FE)-based method for the calculation of eddy current losses in the stator windings of randomly wound electric machines is presented. The method is particularly suitable for implementation in large-scale design optimization algorithms where a qualitative characterization of such losses at higher speeds is most beneficial for identification of the design solutions which exhibit the lowest overall losses including the ac losses in the stator windings. Unlike the common practice of assuming a constant slot fill factor, sf, for all the design variations, the maximum sf in the developed method is determined based on the individual slot structure/dimensions and strand wire specifications. Furthermore, in lieu of detailed modeling of the conductor strands in the initial FE model, which significantly adds to the complexity of the problem, an alternative rectangular coil modeling subject to a subsequent flux mapping technique for determination of the impinging flux on each individual strand is pursued. Rather than pursuing the precise estimation of ac conductor losses, the research focus of this paper is placed on the development of a computationally efficient technique for the derivation of strand eddy current losses applicable in design-optimization, especially where both the electromagnetic and thermal machine behavior are accounted for. A fractional slot concentrated winding (FSCW) permanent magnet (PM) synchronous machineis used for the purpose of this study due to the higher slot leakage flux and slot opening fringing flux of such machines, which are the major contributors to strand eddy current losses in the windings. The analysis is supplemented with an investigation on the influence of the electrical loading on ac winging loss effects for this machine design, a subject which has received less attention in the literature. Experimental ac loss measurements on a 12-slot 10-pole stator assembly will be discussed to verify the existing trends in the simulation results.


Publication metadata

Author(s): Fatemi A, Ionel DM, Demerdash NAO, Staton DA, Wrobel R, Chong YC

Publication type: Article

Publication status: Published

Journal: IEEE Transactions on Industry Applications

Year: 2019

Pages: Epub ahead of print

Online publication date: 07/03/2019

Acceptance date: 11/02/2019

ISSN (print): 0093-9994

ISSN (electronic): 1939-9367

Publisher: IEEE

URL: https://doi.org/10.1109/TIA.2019.2903406

DOI: 10.1109/TIA.2019.2903406


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