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’s permanent magnets has been 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. an initial electromagnetic analysis is, first, carried out using the finite element method. a sensitivity 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 between the proposed structures and the conventional bldc structures. the results reveal that the proposed motor has a considerably lower torque 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