Cogging Torque Reduction of Brushless DC Motor: Investigating the Efficacy of Ra-dial Pole Shaping Technique with Novel Bump-Shaped Rotor Pole

Abstract

With the rising demand for high-performance motors in electrical vehicle applications, permanent magnet brushless DC motors are a promising solution due to their various attractive features. However, it has a significant drawback of high cogging torque, which deteriorates the overall motor performance. This negative impact is dominating in electric vehicles for low-speed applications. It is desirable to reduce the cogging torque to improve the performance of the radial flux brushless DC motor. The prime focus of this research is reducing cogging torque through the radial pole shaping technique with a bump-shaped rotor pole surface. This work also investigates the impact of the proposed approach on torque ripple and motor performance while cutting down the requirement for rare earth material. This paper uses two ratings: 1000 W, 510 rpm, and 250 W, 150 rpm motors. Two reference motors of proposed ratings were designed using radial-shaped permanent magnet poles. Finite element software is used for the simulation and modeling of the motors. A novel bump-shaped permanent magnet pole shape is introduced, and in-depth investigations have been carried out to evaluate the impact of the proposed pole shape on cogging torque. The validity of the analysis results is further substantiated by comparing the improved and reference model results. The comparison investigation indicates that the motor equipped with the proposed pole shape performs better than the reference motor.