三种充磁方式轴向磁齿轮的磁场和转矩特性比较

依据永磁体充磁方向和排列方式的不同,轴向磁齿轮可分为轴向充磁磁齿轮、聚磁式轴向磁齿轮和Halbach式轴向磁齿轮。采用3D有限元法对三种轴向磁齿轮的磁场、转矩特性和轴向力进行了比较。基于气隙磁场的谐波分析,利用公式计算出各次谐波磁场产生的转矩和轴向力,得出各次谐波磁场对转矩传递和轴向力的作用。比较表明,聚磁式轴向磁齿轮的转矩能力和永磁体利用率最大,比轴向充磁磁齿轮提高了17.5%和32.6%,比Halbach式轴向磁齿轮提高了2%和15.1%。Halbach式轴向磁齿轮的气隙中引起转矩波动的磁场谐波的幅值最小,转矩波动也最小。轴向充磁磁齿轮低速转子的轴向力最小,比聚磁式轴向磁齿轮小38.3%,比Halbach式轴向磁齿轮小32.7%。

Comparison of Magnetic Field and Torque Characteristics of Axial Magnetic Gears with Three Magnetization Methods

According to the magnetization direction and arrangement of permanent magnets,axial magnetic gears can be divided into the axial flux magnetic gear(AFMG),the axial flux focusing magnetic gear(AFFMG)and the axial magnetic gear with Halbach permanent magnet arrays(HAMG).3D finite element method was used to compare magnetic field,torque characteristics and axial force of three axial magnetic gears.Based on the harmonic analysis of magnetic field in the air gap,the torque and axial force generated by magnetic harmonics were calculated by formulas,and the effects of magnetic harmonics on the torque transmission and the axial force were clarified.The comparison demonstrates that the torque capability and permanent magnet utilization efficiency of the AFFMG is largest,which shows a 17.5% and 32.6% growth over the AFMG,and 2%and 15.1% growth over the HAMG.The HAMG has the smallest torque ripple because the amplitudes of magnetic harmonics causing torque ripple in the air-gaps are minimal.The low speed rotor of the AFMG has the lowest axial force,38.3%smaller than the AFFMG,and 32.7% smaller than the HAMG.