一种低干扰力矩的三自由度球面磁轴承

提出一种低干扰力矩的三自由度球面磁轴承结构，球面磁轴承定、转子均采用球面结构。当磁通作用在转子的球形包络面时，产生的电磁力会指向转子球心，不会对转子产生干扰力矩，但少量的漏磁磁通会作用在转子的非球形平面上，导致低干扰力矩的出现。利用等效磁路法对球形转子偏转时轴向部分漏磁导致的干扰力矩进行分析，得出干扰力矩的数学表达式。运用有限元法分析球面磁轴承和柱面磁轴承产生偏转时的干扰力矩，结果表明干扰力矩随着转子偏转角度的增加而增大，当转子偏转角达到最大允许值0.3°时，球面磁轴承与柱面磁轴承相比干扰力矩减小两个数量级。球面磁轴承的低干扰力矩特性决定其特别适用于磁悬浮控制力矩陀螺，可提高陀螺的控制精度，在磁悬浮高能密度电机、其他飞轮系统等场合具有广阔的应用前景。

Three Degree of Freedom Spherical Magnetic Bearing with Low Interference Torque

A three-degree-of-freedom spherical magnetic bearing with low interference torque is proposed. Both the stator and rotor of the spherical magnetic bearing adopt spherical structure. When the magnetic flux acts on the spherical envelope of the rotor, the electromagnetic force will point to the centre of the rotor which can reduce the interference of the stator poles on the rotor torque. But the magnetic flux leakage will act on the spherical surface of the rotor, resulting in low interference torque. Due to the complexity of the magnetic flux leakage situation of magnetic bearing, by using the theory of equivalent magnetic circuit method, the interference torque caused by the axial part of the magnetic flux leakage is calculated. Then, the finite element method is used to analyze the interference torque caused by the deflection of the spherical magnetic bearing and the cylindrical magnetic bearing. The calculating results show that the interference torque of the spherical magnetic bearing is far less than that of the cylindrical magnetic bearing. Therefore, the designed spherical bearing has the advantages of low interference torque, and can improve control accuracy of maglev control moment gyroscope. It has wide applications in maglev high energy density motor and other flywheel systems.