Optimization of shield thickness of finite-length solid rotors for eddy-current loss minimization

Manoj R. Shah, Sang Bin Lee

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


A high-conductivity shield is often used for coating the rotor of solid-rotor synchronous machines for reducing the surface eddy-current losses due to armature-reaction space/time harmonics and/or tooth ripple. Since the design process for determining the optimal shield thickness can be complicated and time consuming, a simple analytical model based on Maxwell's equations was developed and presented in a previous paper to simplify the process. It has been shown that such an analytical tool can be used as a quick and effective "screening tool" for determining the range of the optimal shield thickness for minimizing rotor surface losses; however, the influence of finite rotor axial length including the end-face losses was not taken into account. In this paper, an additional step is introduced in the shield design process where a special finite-element (FE) method that accounts for the impact of finite rotor axial length is employed for refining the design obtained from the analytical solution. Comparisons are made for a number of shield thicknesses and rotor lengths for significant space and time harmonic combinations to verify the validity of the proposed two-step design process (analytical and FE) and to evaluate the impact of the finite length of solid rotors.

Original languageEnglish
Article number5238577
Pages (from-to)1947-1953
Number of pages7
JournalIEEE Transactions on Industry Applications
Issue number6
Publication statusPublished - 2009 Nov

Bibliographical note

Funding Information:
Paper IPCSD-09-007, presented at the 2006 Industry Applications Society Annual Meeting, Tampa, FL, October 8–12, and approved for publication in the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Electric Machines Committee of the IEEE Industry Applications Society. Manuscript submitted for review February 1, 2007 and released for publication April 16, 2009. First published September 15, 2009; current version published November 18, 2009. This work was supported by the U.S. Air Force under USAF Contract FA8650-04-G-2466, and in part by the Ministry of Commerce, Industry, and Energy (MOCIE) through the Electrical Industry Research Center (EIRC) program with the Advanced Power Systems Research Center at Korea University.

Copyright 2011 Elsevier B.V., All rights reserved.


  • Ac machines
  • Analytical and numerical harmonic analyses
  • Eddy currents
  • Electromagnetic shielding
  • Rotor surface losses
  • Solid rotor
  • Synchronous machines

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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