| Some places require low-speed direct drive, needs a kind of motor with small diameter (100mm or so) and the output torque ability to hundreds Nm. For the demand of such direct drive motor, this paper studies the torque generation mechanism of Low-speed Axial Permanent Magnet Synchronous Motor (Hereinafter referred to: Ls-A-Pmsm). And for its structural characteristics, set up a torque calculation model of3D magnetic field, have studied its torque affect factors. The main innovations are summarized as follows:1. For the motor’s magnetic field is complex because of its axial and radial distribution characteristics, established a3D-FEM analysis model and corresponding torque calculation model. Combined the theoretical analysis and numerical calculations, reveals the basic relationship among the electromagnetic torque and torque angle and the relative position of the rotor.2. Have carried out a detailed analysis of calculation parameters (including element type&density, air-gap layer form, axial section, the path of Maxwell stress method, silicon steel axial clearance) on the accuracy of calculation.3. Have also carried out a detailed analysis of design parameters (including the diameter, axial length, gap length, thickness of magnet, tooth width, armature current and coercive force) on torque performance of the motor. Provided technical support for carrying out the design and study on Small-diameter low-speed high-torque direct drive motor.4. On the starting performance of the simulation and experimental study also found that when the rotor be blocked, the motor’s output torque fluctuate with current phase, but still has very high start ability.5. Using two testing methods in the motor’s measurement study:one is through the pulley height hanging heavy objects, although not precise enough, it is able to quickly and visually determine starting capability; The other is the coaxial small unit bench with rated torque of20Nm, The integrated test-bed can get starting process curve of speed and torque varying with time, Finally, verified simulation accuracy by compared with experimental results. |
