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

Abstract

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