Analysis and Design of High Torque Density Robotic Joint Motors Based on Equivalent Magnetic Circuits

The electric drive method is considered to be one of the most promising methods for robots, and the joint motors play a crucial role in the performance of robots. In order to improve the torque density of the joint motor, this paper does not use a permanent magnet synchronous motor (PMSM), but uses the magnetic field modulation effect to design a permanent magnet vernier motor (PMVM). In this paper, the performance index of the joint motor is firstly determined according to the robot requirements, and several slot-pole fits that meet the requirements are given. Then, the equivalent magnetic circuit (EMC) model of the joint motor was established, and the electromagnetic performance of the joint motor was theoretically deduced and compared with the finite element analysis. The prototype was fabricated and experimentally tested.