Research Papers

Experimental Characterization and Modeling of Thermal Contact Resistance of Electric Machine Stator-to-Cooling Jacket Interface Under Interference Fit Loading

[+] Author and Article Information
J. Emily Cousineau

National Renewable Energy Laboratory (NREL),
15013 Denver West Parkway,
Golden, CO 80401
e-mail: Emily.Cousineau@nrel.gov

Kevin Bennion

National Renewable Energy Laboratory (NREL),
15013 Denver West Parkway,
Golden, CO 80401

Victor Chieduko

UQM Technologies, Inc.,
4120 Specialty Pl.,
Longmont, CO 80504

Rajiv Lall, Alan Gilbert

UQM Technologies, Inc.,
4120 Specialty Pl.,
Longmont, CO 80504

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS. Manuscript received July 6, 2017; final manuscript received January 15, 2018; published online May 8, 2018. Assoc. Editor: Steve Q. Cai. The United States Government retains, and by accepting the article for publication, the publisher acknowledges that the United States Government retains, a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States government purposes.

J. Thermal Sci. Eng. Appl 10(4), 041016 (May 08, 2018) (7 pages) Paper No: TSEA-17-1239; doi: 10.1115/1.4039459 History: Received July 06, 2017; Revised January 15, 2018

Cooling of electric machines is a key to increasing power density and improving reliability. This paper focuses on the design of a machine using a cooling jacket wrapped around the stator. The thermal contact resistance (TCR) between the electric machine stator and cooling jacket is a significant factor in overall performance and is not well characterized. This interface is typically an interference fit subject to compressive pressure exceeding 5 MPa. An experimental investigation of this interface was carried out using a thermal transmittance setup using pressures between 5 and 10 MPa. The results were compared to currently available models for contact resistance, and one model was adapted for prediction of TCR in future motor designs.

Copyright © 2018 by ASME
Your Session has timed out. Please sign back in to continue.


Stone, G. C. , Boulter, E. A. , Culbert, I. , and Dhirani, H. , 2004, Electrical Insulation for Rotating Machines: Design, Evaluation, Aging, Testing, and Repair, Wiley, Hoboken, NJ.
Popescu, M. , Staton, D. A. , Boglietti, A. , Cavagnino, A. , Hawkins, D. , and Goss, J. , 2016, “Modern Heat Extraction Systems for Power Traction Machines—A Review,” IEEE Trans. Ind. Appl., 52(3), pp. 2167–2175. [CrossRef]
Lutz, J. , 2014, “Unique Lanthide-Free Motor Construction,” 2014 Annual Merit Review, Washington, DC, accessed Nov. 29, 2016, http://energy.gov/sites/prod/files/2014/07/f17/ape044_lutz_2014_o.pdf
Lindström, J. , 1999, Thermal Model of a Permanent-Magnet Motor for a Hybrid Electric Vehicle, Chalmers University of Technology, Gothenburg, Sweden.
Staton, D. , Boglietti, A. , and Cavagnino, A. , 2005, “Solving the More Difficult Aspects of Electric Motor Thermal Analysis in Small and Medium Size Industrial Induction Motors,” IEEE Trans. Energy Convers., 20(3), pp. 620–628. [CrossRef]
Mikić, B. B. , 1974, “Thermal Contact Conductance; Theoretical Considerations,” Int. J. Heat Mass Transfer, 17(2), pp. 205–214. [CrossRef]
Madhusudana, C. , 2014, Thermal Contact Conductance, 2nd ed., Springer, Cham, Switzerland. [CrossRef]
Kulkarni, D. P. , Rupertus, G. , and Chen, E. , 2012, “Experimental Investigation of Contact Resistance for Water Cooled Jacket for Electric Motors and Generators,” IEEE Trans. Energy Convers., 27(1), pp. 204–210. [CrossRef]
ASTM D09 Committee, 2012, “Standard Test Method for Thermal Transmission Properties of Thermally Conductive Electrical Insulation Materials,” ASTM International, West Conshohocken, PA, Standard No. ASTM D5470-06. https://www.astm.org/DATABASE.CART/HISTORICAL/D5470-06.htm
Ley, J. , 2015, “Unique Lanthide-Free Motor Construction,” 2015 Annual Merit Review, Washington, DC, accessed Nov. 29, 2016, http://energy.gov/sites/prod/files/2015/06/f24/edt044_gilbert_2015_o.pdf
Narumanchi, S. , Mihalic, M. , Kelly, K. , and Eesley, G. , 2008, “Thermal Interface Materials for Power Electronics Applications,” 11th Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITHERM), Orlando, FL, May 28–31, pp. 395–404.
Kirkup, L. , 2002, Data Analysis With Excel®: an Introduction for Physical Scientists, Cambridge University Press, Cambridge, UK.
Dieck, R. H. , 2007, Measurement Uncertainty: Methods and Applications, ISA, Research Triangle Park, NC.
Madhusudana, C. V. , and Fletcher, L. S. , 1981, “Gas Conductance Contribution to Contact Heat Transfer,” AIAA Paper No. 81-1163.
Antonetti, V. W. , Whittle, T. D. , and Simons, R. E. , 1993, “An Approximate Thermal Contact Conductance Correlation,” ASME J. Electron. Packag., 115(1), pp. 131–134. [CrossRef]


Grahic Jump Location
Fig. 1

Electric machine cross section highlighting stator-to-case contact

Grahic Jump Location
Fig. 2

Top: machine stator surface. Bottom: case interior surface.

Grahic Jump Location
Fig. 3

High-pressure thermal transmittance setup showing cutaway view of sample stabilizing rig

Grahic Jump Location
Fig. 4

Edge views of lamination materials. The microscope stage is labeled for clarity.

Grahic Jump Location
Fig. 5

Ten-mm square sample area surface profile of the contact plate

Grahic Jump Location
Fig. 6

Thermal resistance as a function of lamination coupon thickness

Grahic Jump Location
Fig. 7

Comparison of contact plate surface finish effect on TCR

Grahic Jump Location
Fig. 8

Total thermal resistance measurements for M15 29-gauge coupons at 5.52 MPa with extrapolation to 0 lamination coupon thickness

Grahic Jump Location
Fig. 9

Top: stator-to-case TCR results. Bottom: lamination effective thermal conductivity results. Error bars represent the 95% confidence interval.

Grahic Jump Location
Fig. 10

Top: Comparison of TCR model to M15 29-gauge data. Bottom: comparison of TCR model to JFE (0.2 mm) data. Root mean square surface roughness of the contacting surfaces used in the model is noted on the plot. Error bars indicate 95% confidence interval for the data.



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In