Effect of Slot Opening on the Cogging Torque of Fractional-Slot Concentrated Winding Permanent Magnet Brushless DC Motor

  • Yan, Jianhu ;
  • Zhang, Qiongfang ;
  • Feng, Yi
  • Received : 2015.10.30
  • Accepted : 2016.01.20
  • Published : 2016.03.31


Cogging torque will affect the performance of a permanent magnet Brushless DC Motor (BLDCM), thus the reduction of cogging torque is key for BLDCM optimization. In this paper, the phase shifting of cogging torque for a fractional-slot concentrated winding BLDCM is analyzed using the Maxwell tensor method. Moreover, a 9-slot 10-pole concentrated winding BLDCM driven by ideal square waveform is studied with the finite element method (FEM). An effective method to reduce the cogging torque is obtained by adjusting the slot opening. In addition, the influences of different slot openings on back electromotive force (back-EMF), air gap flux density and flux linkage are investigated and experimentally validated using the prototype BLDCM.


BLDCM;cogging torque;concentrated winding;finite element method;fractional-slot;slot opening


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