Electromagnetic design of a high torque density permanent magnet motor for biomimetic robot

摘要

The limitations in achieving the goal of building the faster biomimetic robot are the torque produced from motors used to power the robot, as well as the mass and power dissipation of these motors. These limitations formulate the need for a low-mass high-torque motor. In order to improve the torque density of the motor, this paper outlines the electromagnetic design of a permanent magnet brushless DC motor with fractional slot concentrated winding that meet the goals of the robot while minimizing the total mass. The basis of the pole-slot numbers combination of the motor with fractional-slot concentrated windings is analyzed, and the magnetic fields of the motor which produced by permanent magnet and windings current are calculated on the basis of the permanent magnet field and airgap field. Moreover, finite element analysis for the motor is carried out to investigate the distribution of the magnetic field, back electromotive force, core loss, steady torque and cogging torque. The results prove the feasibility of the design method, and the torque density of the motor is 3.47Nm/kg.