Improved Rotor Designs of V- and Flat-type BLDC Motors Aiming at Low Torque Ripple

This paper presents modified rotor designs for two conventional V- and Flat-type BLDC motors to reduce the torque ripple. For gaining an insight into design features, the torque production characteristics are described at the beginning of the paper. By analyzing and comparing performance parameters including cogging torque, air gap flux density, back EMF, and torque average, the paper tries to describe how the torque ripple can be affected and reduced by shaping the air gap and creating specific holes in the rotor magnetic path. First, the conventional V-type BLDC motor was analyzed. Sensitivity analysis was deployed to shape the air gap and to create holes in the rotor structure. Then, all the results for both conventional and proposed V-type models were compared. Consequently, the torque ripple was effectively reduced without affecting other performance parameters. Next, the Flat-type BLDC motor was considered. Following the sensitivity analysis, the air gap was shaped, and holes were created. Similar to the proposed V-type design, the proposed Flat-type design effectively reduced the torque ripple compared with the conventional design. The results were obtained using finite element analysis; it confirmed the effectiveness of the proposed designs in both V- and Flat-type BLDC motors.