Factor analysis of torque ripple reduction in synchronous reluctance motors derived from topology optimization

Hiroyuki Kaimori*, Yoshifumi Okamoto, Shinji Wakao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Recently, from the viewpoint of vibration and noise reductions, torque ripple reduction of motor-equipped electrical machines is the need of the hour. The authors have already proposed to improve torque characteristics of a synchronous reluctance motor using the topology optimization method. The evaluated rotor structure succeeded in substantial torque ripple reduction, but the cause for this reduction was unknown. In this paper, we investigate the reason for torque ripple reduction using the improved rotor structure of the motor by a topology optimization method known as R-SLP, by comparing it to the reference model using finite element analysis. A calculation method is proposed to analyze the circumferential magnetic force density of spatial and time harmonic orders using the magnetic density in the air gap. By focusing on the time order at which the torque waveform was evaluated, we estimate which circumferential magnetic force density orders affect torque ripple reduction. Then, we clarify the reason for torque ripple reduction to examine the influence of local shape of rotor structure using 12 th time-harmonic magnetic fields. As a result, the modified flux barrier rotor structure is obtained, which further reduces the torque ripple in comparison to the previous structure.

Original languageEnglish
Pages (from-to)380-387
Number of pages8
Journalieej transactions on industry applications
Issue number4
Publication statusPublished - 2019 Jan 1


  • Finite element analysis
  • Flux barrier
  • Synchronous motor
  • Topology optimization
  • Torque ripple

ASJC Scopus subject areas

  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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