单极内嵌两相混合式步进电机

Homopolar Interior Permanent Magnet Two-phase Hybrid Stepping Motor

传统型混合式步进电机(HSM)采用轴向永磁磁路结构,环形永磁体放置在转子上,其截面积受转子铁心内、外径的限制,磁钢用量有限;其转子常采用多段式以缩短磁路,解决永磁磁通沿轴向衰减问题,但转子分段的增加导致转子有效铁心占比的减小,限制了电机的转矩密度,且轴向长度的增加在电机安装尺寸受限的情况下并不适用。本文提出了一种两相单极内嵌式HSM,转子铁心轴向分两段,错开半个齿距,每段内嵌两个半圆瓦片形径向充磁同极性永磁体。该结构永磁体不额外占用轴向空间,且磁通沿轴向衰减较小,从而减小了电机体积,提高了转矩密度。本文首先介绍了单极内嵌式HSM的电机结构及工作原理;其次,为了与传统HSM作对比,采用传统57型HSM结构参数,基于三维有限元设计了相同体积的单极内嵌式HSM样机电磁方案,仿真分析了其空载磁场和气隙磁密分布,对比分析了两种电机的稳态运行性能,仿真结果表明,与相同尺寸的传统型HSM相比,单极内嵌式HSM的额定保持转矩和输出转矩均大于传统型HSM。

The traditional hybrid stepping motor(HSM) adopts an axial permanent magnetic circle structure, where the annular permanent magnet is placed between two rotors and thus the amount of magnetic steel is limited because of the given rotor core’s parameter. In addition, to solve the problem that permanent magnet flux is severely reduced axially, traditional HSM has generally the multi-section rotor structure, but the increasing rotor sections result in a reduction in the effective proportion of the rotor, limiting the torque density of the motor, and a motor with big axial length is not applicable in some specific cases. A homopolar interior permanent magnet HSM was presented, in which the rotor has two half-rotors arranged with non-alignment and two semi-circular homopolar permanent magnets were embedded in each half-rotor. Since in this structure permanent magnet does not occupy any axial space, and the magnetic flux is uniform relatively axially, the motor volume is reduced and the torque density is improved. First, the structure and working principle of the homopolar interior permanent magnet HSM were introduced. Secondly, in order to compare with the traditional HSM, the traditional 57-type HSM structural parameters were used, and a homopolar interior permanent magnet HSM with the same volume was designed based on 3-D finite element. Furthermore, the simulation about this motor was analyzed, which obtained its magnetic field and air gap magnetic distribution on the no-load condition, and compared the steady state operation performance of two motors. The simulation results show that the rated holding torque and output torque of the homopolar interior permanent magnet HSM are both greater than the traditional HSM of the equal motor volume.