Saliency ratio and power factor of IPM motors optimally designed for high efficiency and low cost objectives

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

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

16 Scopus citations


This study uses formal mathematical optimization techniques based on parametric 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 wide constant-power flux-weakening range. Only the first two objectives are considered for constant-torque applications. Two types of Interior Permanent Magnet (IPM) 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 miss-conception, the saliency ratio can 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
Title of host publication2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014
Number of pages7
ISBN (Electronic)9781479956982
StatePublished - Nov 11 2014

Publication series

Name2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014

Bibliographical note

Publisher Copyright:
© 2014 IEEE.


  • Constant power control
  • Design optimization
  • Differential evolution
  • Finite element analysis
  • Maximum torque per ampere
  • Permanent magnet machine
  • Power factor
  • Saliency ratio

ASJC Scopus subject areas

  • Fuel Technology
  • Energy Engineering and Power Technology


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