Design And Research On A Novel Field Modulated Magnetic Gear

Magnetic gears, whose input sides are physically isolated with the output sides, have special advantages over mechanical gears in some occasions. However, traditional magnetic gears have low torque density, because they are poor utilities of permanent magnets, which limits their applications greatly. The novel field modulated magnetic gear (FMMG) is concentric configuration thus can enhance the utilities of permanent magnets greatly. Its torque density can be several times bigger than the traditional one's, so field modulated magnetic gear will have broad applications. The works in this thesis are focused on design and research on this novel magnetic gear. Generally speaking, the main works include the following ones:Firstly, the basic principle of FMMG is elaborated by both analytical method and two-dimensional (2D) finite element method (FEM). In FEM analysis, special work is done to the modulator ring to stand out its field modulated function in the gear. Based on the research on the cogging torque in this kind of magnetic gear, a novel FMMG with ratio 7.33:1 is proposed. Then, the two most important characteristics of magnetic gear, namely static torque characteristic and the stable torque characteristic are analyzed by the static field computations.Secondly, according to the papers published by foreign researchers, the maximum static torques computed by 2D FEM exhibited serious errors with respect to the actual results. In this thesis, a 3D-FEM is developed to analyze the end-effect of the FMMG The key is to adopt the scalar magnetic potential so that the required data manipulation and computation can be significantly reduced. A realistic magnetic gear is analyzed by using both the proposed 3D-FEM and the traditional 2D-FEM, which shows the accuracy of the developed 3D-FEM. And the computed result also shows the proposed 3D-FEM can get the results within a reasonable time, which makes the possibility to use the proposed 3D-FEM to do optical design in regards of computation time.Thirdly, in this thesis the author carries on research on the iron core losses in FMMG by the FEM. Thus the author points out design guidelines to reduce the iron core losses. The optical choice of the number of the inner rotor pole pairs is also done by the author, with the respects to iron losses, cogging torque, mechanical arts and crafts and so on.Then, a new topology of this MFMG, which improvement is done in the outer rotor and has already been applied for a patent by the author, is proposed. Optimization work is done by the 3D FEM to find out the influence of the main parameters on the performance of the MFMG Then a prototype of this new topology is developed and test is done to the prototype. Test results show both the torque density and the efficiency of the prototype are high enough to practical applications.Finally, dynamic performance of the MFMG is done by the author. Magnetic gears have no self-start ability and they must be driven by a external equipment, so in order to do research on the dynamic performance of magnetic gears the model must include both the magnetic gear and the external equipment. In this thesis the Co-simulation FEM model of motor and magnetic gear is established and hence the dynamic performance of the transmission system is studied.