Saliency Ratio and Power Factor of IPM Motors with Distributed Windings Optimally Designed for High Efficiency and Low-Cost Applications

Peng Zhang, Dan M. Ionel, Nabeel A.O. Demerdash

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


This paper uses formal mathematical optimization techniques based on parametric finite-element-based computationally efficient models and differential evolution algorithms. For constant-power applications, in the novel approach described, three concurrent objective functions are minimized: material cost, losses, in order to ensure high efficiency, and the difference between the rated and the characteristic current, aiming to achieve very high constant-power flux-weakening range. Only the first two objectives are considered for constant-Torque applications. Two types of interior permanent magnet rotors in a single-and double-layer V-shaped configuration are considered, respectively. The stator has the typical two slots per pole and phase distributed winding configuration. The results for the constant-Torque design show that, in line with expectations, high efficiency and high power factor machines are more costly, and that the low-cost machines have poorer efficiency and power factor and most importantly, and despite a common misconception, the saliency ratio may also be lower in this case. For constant-power designs, the saliency ratio can be beneficial. Nevertheless, despite a common misconception, when cost is considered alongside performance as an objective, a higher saliency ratio does not necessarily improve the power factors of motors suitable for ideal infinite flux weakening.

Original languageEnglish
Article number7534769
Pages (from-to)4730-4739
Number of pages10
JournalIEEE Transactions on Industry Applications
Issue number6
StatePublished - Nov 1 2016

Bibliographical note

Funding Information:
National Science Foundation

Publisher Copyright:
© 1972-2012 IEEE.


  • Constant-power operation
  • design optimization
  • differential evolution (DE)
  • finite-element analysis (FEA)
  • maximum torque per ampere (MTPA)
  • permanent magnet (PM) machine
  • power factor
  • saliency ratio

ASJC Scopus subject areas

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


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