Optimization Design And Comparative Study Of High Torque Density Permanent Magnetic Gears

With the development of science and technology,higher requirements have been placed on gear transmissions in many emerging fields.Mechanical gears have some inherent problems such as contact friction,noise,mechanical vibration and require periodic lubrication and maintenance.Thence,magnetic gears which transmit torque and speed through the coupling magnetic field are rapidly developed.Among the many magnetic gears,magnetic planetary gear(MPG)and coaxial magnetic gear(CMG)have received extensive attention from scholars due to their high torque density and multi-port characteristics,and have been investigated for emerging fields such as hybrid vehicles and wind power generation.At present,scholars mainly focus on the study of the topological structure and dynamic response performance of MPG and CMG,respectively.The systematically quantitative analysis and comparison of the torque transmission performances of the aforementioned two types of high torque density magnetic gears are rarely performed.In addition,the systematic design optimization methods is still absent for the relatively complex structure of the MPGs,leading to a low design efficiency,which can-not meet the relevant design requirements.Therefore,this paper focuses on the following works for the above two major problems:Firstly,detailed description of the structural features and operating principles of the MPG and CMG,then the transmission relationships between different components of the two types of high torque density magnetic gears in different operating modes are analyzed,which provides a basic theoretical guidance for design a high torque density magnetic gear.Based on the corresponding theoretical basis,the MPG and CMG with same amount of permanent magnets and same effective volume are designed by quantitative design method.Then,the torque transmission performances of the MPG and the CMG are compared objectively and fairly using the finite element analysis method.By analyzing the torque produced by different air-gap field harmonics,the differences in torque transmission performance between MPG and CMG are clarified.Secondly,the influences of permanent magnet magnetization direction on the torque transmission performance of the MPG is investigated since its torque transmission based on multiple magnetic coupling.By introducing the idea of stratified optimization design,the MPG is optimal designed by multi-objective stratified hybrid optimization method considering the potential application for hybrid vehicles.During the optimization process,the dual orientation permanent magnent shaping method is presented,to greatly reduce the cogging torque and torque ripple of the MPG.Finally,based on the optimization results,a prototype of MPG is designed and manufactured.Then,corresponding hybrid powertrain test platform is established to test the torque transmission performances of the designed prototype.The experimental results verify the effectiveness and rationality of the design optimization method proposed is this paper,which provides a corresponding theoretical basis and experimental support for further research on high torque density magnetic gears.