洛伦兹力磁轴承磁密均匀度设计与分析

新型磁悬浮控制敏感陀螺(MSCSG)高速转子具有万向偏转特性,可输出高精度和高带宽的偏转控制力矩,用于抑制天基平台的周期性振动。MSCSG采用5自由度(DOF)全主动控制,其径向2个扭动DOF的偏转控制由洛伦兹力磁轴承(LFMB)实现。基于LFMB的基本构型,建立电磁力和电磁力矩的数学模型,并分析出气隙磁密均匀度是影响输出力矩精度和角速率测量精度的主要因素。介绍了LFMB的优化设计结构,通过有限元仿真分析,结果表明所设计LFMB通过在内外永磁体表面增加1J50导磁薄片,能够有效提高气隙磁密分布的均匀度,输出控制力矩更加精确,有利于提高控制精度;通过使用梯形永磁体提供更大的供磁面积提高气隙磁密强度以降低功耗,同时梯形永磁体在转子高速旋转时便于限位,保证稳定性。本文研究可为具有偏转特性的磁悬浮类转子陀螺的设计与分析提供有益参考。

Design and analysis on uniformity of magnetic flux density in Lorentz force-type magnetic bearing

With universal deflection,the high-speed rotor of new magnetically suspended control & sensitive gyroscope (MSCSG) can output high-accuracy and high-bandwidth deflection control torque,which can inhibit periodic vibration of the space-based platform.MSCSG is fully actively controlled in 5 degrees of freedom degrees of freedom (DOF) and its deflection control in 2 radial DOF is realized by Lorentz force-type magnetic bearing (LFMB).Based on basic structure of LFMB,the mathematical model of electromagnetic force and electromagnetic torque were set up and analysis shows that the uniformity of air gap flux density is the main factor that affects output torque accuracy and measuring accuracy of angle rate.The optimized design of LFMB with 1J50 thin slice added to the surface of inside and outside permanent magnet was introduced and the air gap flux density was analyzed to be highly uniform by finite element simulation.The output torque is more accurate and control accuracy is higher.The permanent magnet can support larger magnetic area with a trapezoid cross section to enlarge the air gap flux density and reduce power consumption.Besides,it can remain stable when the rotor is highly rotating.Some useful references can be provided by this paper for the design and analysis of magnetically suspended rotor gyroscope with deflection characteristic.