Design and Analysis of a New Topology of Rotor Magnets in Brushless DC Motors to Reduce Cogging Torque

This paper presents a novel topology of permanent magnet brushless DC motors. Brushless DC motors usually experience torque ripple mainly caused by cogging torque. In the proposed motor, the whole structure of the rotor’spermanent magnets hasbeen changed so that the cogging torque is considerably mitigated. The philosophy behind this modification depends on the  way  of  flux-path  production  in  the rotor  structure  and  it  should  be  similar  to  the  way  of  motor  phases. Aninitial electromagnetic analysis is, first,carried out using the finite element method. Asensitivity analysis is, next,included to obtain the  most  important  design  parameters  for  the  proposed  structure.  The  different  performance  parameters of  the  motor are calculated and compared betweenthe proposed structures and the conventional BLDC structures. The results revealthat the proposed  motor  has  a  considerably lowertorque  ripple  retaining an average  value  of  the  produced  torque.  The  proposed structure  is  also  compared  with an asymmetrical  V-type  structure  and  the  results  further  show  the  effectiveness  of  the proposed structure.

Keywords:

BLDC motor , Cogging torque , Finite Element Analysis , magnetic topology