A Novel Design of a Brushless DC Motor Integrated With an Embedded Planetary Gear Train

This paper presents a novel design by integrating a planetary gear train (PGT) within a brushless DC (BLDC) motor to be a compact structure assembly. It provides functional and structural integrations to overcome inherent disadvantages of traditional designs. The effects of gear teeth on the magnetostatic field of the BLDC motor associated with the kinematics of the PGT are investigated. By designing the numbers of gear teeth integrated on the stator and magnet poles on the rotor, the cogging torque of the proposed motor configuration is effectively reduced. The magnetic field distribution and the output torque of the novel design with different standard gear modules are numerically calculated by the two-dimensional finite-element analysis. Through the kinematic analysis utilizing the fundamental circuits, feasible solutions for the numbers of gear teeth of the PGT are determined to meet the desired speed ratio.