Large-Scale Design Optimization of PM Machines over a Target Operating Cycle

Alireza Fatemi, Nabeel A.O. Demerdash, Thomas W. Nehl, Dan M. Ionel

Research output: Contribution to journalArticlepeer-review

87 Scopus citations


A large-scale finite element model-based design optimization algorithm is developed for improving the drive-cycle efficiency of permanent magnet (PM) synchronous machines with wide operating ranges such as those used in traction propulsion motors. The load operating cycle is efficiently modeled by using a systematic k-means clustering method to identify the operating points representing the high-energy-throughput zones in the torque-speed plane. The machine performance is evaluated over these cyclic representative points using a recently introduced computationally efficient finite element analysis, which is upgraded to include both constant torque and field-weakening operations in the evaluation of the machine performance metrics. In contrast with the common practice, which aims at enhancing the rated performance, the entire range of operation is considered in the present design optimization method. Practical operational constraints imposed by the voltage and current limits of the motor-drive system, excessive PM demagnetization, and torque ripple are accounted for during the optimization process. The convergence to the optimal design solutions is expedited by utilizing a new stochastic optimizer. The developed design algorithm is applicable to any configuration of sinewave-drive PM and synchronous reluctance motors over any conceivable load profile. Its effectiveness is demonstrated by optimizing the well-established benchmark design represented by the Toyota Prius Gen. 2 interior PM motor configuration over a compound operating cycle consisting of common U.S. driving schedules. Multiphysics electromagnetic, thermal, and mechanical performance of the optimized design solutions is discussed in a postdesign optimization stage.

Original languageEnglish
Article number7465805
Pages (from-to)3772-3782
Number of pages11
JournalIEEE Transactions on Industry Applications
Issue number5
StatePublished - Sep 1 2016

Bibliographical note

Publisher Copyright:
© 2016 IEEE.


  • Design optimization
  • Traction motors
  • field-weakening operation
  • finite element analysis (FEA)
  • permanent magnet (PM) machines

ASJC Scopus subject areas

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


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