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Evaluation of Impregnation Materials for Thermal Management of Liquid-Cooled Electric Machines
KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.
KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.ORCID-id: 0000-0002-9855-5105
KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.ORCID-id: 0000-0002-6283-7661
KTH, Skolan för elektro- och systemteknik (EES), Elektrisk energiomvandling.ORCID-id: 0000-0002-0744-2552
2014 (Engelska)Ingår i: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 61, nr 11, s. 5956-5965Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

In this paper, the thermal impact of using different impregnation materials on high-performance liquid-cooled electric machines is studied. In this regard, varnish, Epoxylite, and a silicone-based thermally conductive material are considered. To study thermal effects of using different impregnation materials in theory, an advanced lumped-parameter thermal model of the studied electric machines is developed. In addition to the simulation studies, three identical induction machines using the aforementioned materials are manufactured and evaluated. Experimental tests are carried out at a wide range of current magnitudes and cooling conditions. A good agreement between the temperature measurements and corresponding simulation results is observed. It is demonstrated that using innovative thermally conductive materials in the stator slots and the end winding bodies of liquid-cooled electric machines results in a significant reduction in the winding hot spot temperature. Additionally, the influence of the critical parameters on the impregnation material performance, e. g., impregnation goodness and slot fill factor, is studied.

Ort, förlag, år, upplaga, sidor
2014. Vol. 61, nr 11, s. 5956-5965
Nyckelord [en]
Computational fluid dynamics, direct oil cooling, Epoxylite, hybrid electric vehicle (HEV), impregnation material, induction machines, lumped parameter (LP) thermal model, silicone-based thermally conductive material (SbTCM), vacuum impregnation, varnish
Nationell ämneskategori
Reglerteknik Annan elektroteknik och elektronik
Identifikatorer
URN: urn:nbn:se:kth:diva-122841DOI: 10.1109/TIE.2014.2308151ISI: 000337123000016Scopus ID: 2-s2.0-84902340101OAI: oai:DiVA.org:kth-122841DiVA, id: diva2:623561
Forskningsfinansiär
StandUpEnergimyndigheten
Anmärkning

Updated from Submitted to Published. QC 20140715

Tillgänglig från: 2013-05-28 Skapad: 2013-05-28 Senast uppdaterad: 2017-12-06Bibliografiskt granskad
Ingår i avhandling
1. Thermal Analysis and Management of High-Performance Electrical Machines
Öppna denna publikation i ny flik eller fönster >>Thermal Analysis and Management of High-Performance Electrical Machines
2013 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
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.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2013. s. x, 83
Serie
Trita-EE, ISSN 1653-5146 ; 2013:022
Nyckelord
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.
Nationell ämneskategori
Elektroteknik och elektronik
Identifikatorer
urn:nbn:se:kth:diva-122695 (URN)978-91-7501-733-4 (ISBN)
Disputation
2013-06-13, sal F3, Lindstedtsvägen 26, KTH, Stockholm, 14:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20130528

Tillgänglig från: 2013-05-28 Skapad: 2013-05-27 Senast uppdaterad: 2013-05-28Bibliografiskt granskad

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Krings, AndreasWallmark, OskarLeksell, Mats

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IEEE transactions on industrial electronics (1982. Print)
ReglerteknikAnnan elektroteknik och elektronik

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