Reduction of cogging torque of radial flux permanent magnet brushless DC motors with application of dual permanent magnet materials

Abstract

The cogging torque is a detrimental to the performance of radial flux permanent magnet brushless dc (PMBLDC) motor. It causes vibration and audible noises. This paper presents a design technique for cogging torque reduction of radial flux brushless dc motors. The 200 W, 1000 rpm radial flux BLDC motor is initially designed with NdFeB permanent magnet (PM) material on each rotor pole. Cogging torque profile of initially designed motor is obtained with finite element modelling and analysis. The design is improved with application of dual PM materials. NdFeB and Alnico are alternately placed on rotor pole. The influence of design improvement on cogging torque of radial flux BLDC motor is analyzed by conducting series of FE exercises. It is analyzed that peak cogging torque is reduced from 0.55 N.m. to 0.4 N.m. with application of dual PM material in improved designed motor.