Basic Research On Field-modulated Permanent Magnetic Reducer

Field-modulated Permanent Magnetic Reducer(PMR) is a new kind of device for motion and torque transmission with the interaction of permanent magnetic poles. Due to non-contact mechanism, the problems of mechanical gearbox such as abrasion, wear, acoustic noises etc. could be eliminated, and it also has some other distinct advantages, such as high magnetic energy utilization, high torque density, physical insolation transmission and overload protection.Field-modulated PMR can be classified as radial modulating and axial modulating. Up to now, the research on PMR were mainly focused on structural aspects and static characteristics(or quasi-static characteristics), the basic theoretical problems about PMR has not been systematically studied, so the development and application were badly restricted. The purpose of this thesis is to investigate the influences of structural and material parameters of PMR on its transmission characteristics with the help of FEA software Comsol Multiphysics, and give some reference to the design of PMR.Firstly, mathematical model of transmission is described; By using FEA and harmonic analysis, distribution of magnetic flux density in airgaps adjacent to driving and driven rotors are investigated and thus the modulation and operation principle are intuitively revealed; By analysis of static torque-angle characteristics curve, the operating features are explained.Secondly, by using 2D transient-step FEA, the influences of magnetic pole pairs, transmission ratio, rotational speed, initial angle(external load) on transmission characteristics of radial modulating PMR are investigated, the variation trend of output torque and efficiency are obtained.Thirdly, by using 3D FEA and orthogonal test, the influences of main structural and material performance parameters on static torque of axial modulating PMR are investigated, through range analysis a combination of structural parameters which result in better static output is obtained.Finally, two new devices are proposed, namely high torque disc type PMR and disc type modulating AC permanent magnetic-geared motor. Preliminary simulation shows that the former could offer higher torque density, the latter could give direct low-speed and high output torque.