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Thermal analysis of permanent-magnet synchronous reluctance machines
KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.ORCID iD: 0000-0002-6283-7661
KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.ORCID iD: 0000-0002-0744-2552
2011 (English)In: 14th European Conference on Power Electronics and Applications, 2011Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents a thermal analysis of permanent-magnet synchronous reluctance machines (PM-SRM). Particular focus is put on the rotor and two lumped parameter (LP) thermal models of the rotor are implemented and evaluated. The results of the two LP thermal models are compared to thermal simulations using the finite element method (FEM). Induced eddy current losses in the permanent magnets are computed using three-dimensional (3D) FEM computations whereas the losses in the electrical steel are obtained using a 2D FEM model. Based on type of cooling system, two cases are evaluated and the agreement between the two LP thermal simulations and the thermal FEM simulation is generally good but particular differences are highlighted. In the first case, the water cooling system manages to effectively handle the dominating copper losses which results in only a minor temperature difference between the shaft and the inner part of the stator teeth. In the second case, it is assumed that there is a significant temperature difference between the rotor shaft and the stator.

Place, publisher, year, edition, pages
2011.
Keyword [en]
Electric vehicle, Hybrid electric vehicle, Thermal design, Cooling
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-43249ISI: 000308003502011Scopus ID: 2-s2.0-80053552004ISBN: 978-161284167-0 (print)OAI: oai:DiVA.org:kth-43249DiVA: diva2:448016
Conference
14th European Conference on Power Electronics and Applications, EPE 2011. Birmingham. 30 August 2011 - 1 September 2011
Funder
StandUp
Note

QC 20111116

Available from: 2011-10-13 Created: 2011-10-13 Last updated: 2014-09-11Bibliographically approved
In thesis
1. Thermal Analysis and Management of High-Performance Electrical Machines
Open this publication in new window or tab >>Thermal Analysis and Management of High-Performance Electrical Machines
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with thermal management aspects of electric machinery used in high-performance  applications  with  particular  focus put  on electric machines designed for hybrid electric vehicle applications.

In the first part of this thesis,  new thermal models of liquid (water and oil) cooled electric machines are proposed.  The proposed thermal models are based on a combination of lumped parameter (LP)  and numerical methods. As  a first  case study,  a permanent-magnet  assisted  synchronous reluctance machine (PMaSRM) equipped with a housing water jacket is considered.  Particular focus is put on the stator winding and a thermal model is proposed that divides the stator slot into a number of elliptical copper and impregna- tion layers.  Additionally, an analysis, using results from a proposed simplified thermal finite element (FE)  model representing only a single slot of the sta- tor and its corresponding end winding, is presented in which the number of layers and the proper connection between the parts of the LP thermal model representing the end winding and the active part of winding are determined. The approach is attractive due to its simplicity  and the fact  that it closely models the actual temperature distribution for common slot geometries.  An oil-cooled induction machine where the oil is in direct contact with the stator laminations  is also considered.  Here, a multi-segment structure is proposed that  divides  the  stator,  winding and cooling  system  into  a number  of an- gular  segments.   Thereby,  the  circumferential  temperature  variation  due to the  nonuniform distribution  of the  coolant  in the  cooling  channels  can be predicted.

In the  second part  of this  thesis,  the  thermal  impact  of using  different winding impregnation  and steel  lamination  materials  is  studied.   Conven- tional varnish, epoxy and a silicone based thermally conductive impregnation material are investigated and the resulting temperature distributions in three small induction machines are compared. The thermal impact of using different steel lamination materials is investigated by simulations using the developed thermal  model  of the water  cooled  PMaSRM. The  differences  in alloy con- tents and steel lamination thickness are studied separately and a comparison between the produced iron losses and the resulting hot-spot temperatures is presented.

Finally, FE-based approaches  for  estimating  the  induced  magnet  eddycurrent losses in the rotor of the considered PMaSRM are reviewed and compared in the  form  of a case  study  based on simulations.   A  simplified three-dimensional  FE model  and an analytical  model,  both  combined  with time-domain 2D FE analysis, are shown to predict the induced eddy current losses with a relatively good accuracy compared to a complete 3D FE based model.  Hence, the two simplified approaches are promising which motivates a possible future experimental verification.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. x, 83 p.
Series
Trita-EE, ISSN 1653-5146 ; 2013:022
Keyword
Computational fluid dynamics, directly cooled electric machines, finite element analysis, heat transfer, hybrid electric vehicle, induction machines, lumped-parameter thermal model, permanent-magnet assisted synchronous reluctance machines.
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-122695 (URN)978-91-7501-733-4 (ISBN)
Public defence
2013-06-13, sal F3, Lindstedtsvägen 26, KTH, Stockholm, 14:00 (English)
Opponent
Supervisors
Note

QC 20130528

Available from: 2013-05-28 Created: 2013-05-27 Last updated: 2013-05-28Bibliographically approved

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Wallmark, OskarLeksell, Mats

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