Design of Optimal Outer Rotor Brushless DC Motor for Minimum Cogging Torque

This paper presents the optimum design for outer rotor brushless dc motor. The purpose of the research was to obtain optimum design for the DC motor with low level cogging torque. First, the simulation using was carried out using Ansys software to investigate the limit of number of rotor and stator of 90 mm diameter motors. Effect of the slots number on cogging torque was studied by variations in slots number. It was found that 26 slots produced minimum cogging torque. Research was then continued by variating poles number. The results showed that cogging torque did not change with the changes in poles numbers. Slot aperture opening significantly influenced cogging torque generation. Wider slot opening produced higher cogging torque.