A novel configuration for a brushless DC motor with an integrated planetary gear train

This paper presents a novel configuration of a brushless DC (BLDC) motor with an integrated planetary gear train, which provides further functional and structural integrations to overcome inherent drawbacks of traditional designs. The effects of gear teeth on the magnetic field and performance of the BLDC motor are investigated. Two standard gear profile systems integrated on the stator with feasible numbers of gear teeth are introduced to reduce the cogging torque. An equivalent magnetic circuit model and an air-gap permeance model are applied to analytically analyze the magnetic field, while the validity is verified by 2-D finite-element method (FEM). Furthermore, the motor performance is discussed and compared with an existing design. The results show that the present design has the characteristics of lower cogging torque and torque ripple than the conventional design, which is of benefit to the widely applications on accurate motion and position control for BLDC motors.