【作者】 丁国平；

【导师】 周祖德；

【作者基本信息】 武汉理工大学 ， 机械制造及其自动化， 2008， 博士

【摘要】 磁力轴承是典型的电磁能和机械能相互转化的装置,其电磁场特征从本质上反映了磁力轴承的整体性能。磁力轴承的磁性材料的非线性磁导率和磁饱和、漏磁、磁耦合、涡流等因素使得磁力轴承电磁场具有很强的空间非线性和动态特征。因此通过理论计算和实验测量相结合的方法研究磁力轴承电磁场的空间分布和变化规律对于提高磁力轴承的整体性能具有重要意义。本文以八极径向磁力轴承为例,针对磁力轴承转子静态悬浮和动态悬浮(旋转)这两种典型运行状态,推导出磁力轴承电磁场的磁势方程,界定了磁力轴承电磁场的边界条件,选用有限元方法求解磁力轴承电磁场边值问题。针对转子静态悬浮状态,建立磁力轴承静态电磁场模型。考虑定子和转子铁磁材料的BH曲线、磁饱和、漏磁、磁耦合等非线性因素,使用三维有限元方法计算磁力轴承静态电磁场的空间分布,结果表明上述非线性因素对磁力轴承的关键性能参数—气隙磁通密度和磁力有显著影响。构建了径向磁力轴承实验装置静态电磁场测量平台,使用三通道高斯计测量了径向磁力轴承实验装置的磁通密度分布,使用磁通密度的实测值对电磁场三维有限元模型进行了修正,修正后的有限元模型达到一定的准确性。针对转子旋转状态,建立磁力轴承旋转电磁场模型。使用二维非线性有限元方法求解了不同线圈电流、转速条件下的磁力轴承旋转电磁场的磁力线分布、气隙磁通密度、悬浮力、拖曳力和功率损耗。结果表明转子材料的磁饱和使气隙磁通密度、拖曳力出现明显饱和,饱和点由线圈电流和转子转速共同决定。为解决磁力轴承气隙磁场的在线测量问题,提出将光纤布喇格光栅(FiberBragg Grating,FBG)应用于气隙磁通密度测量,设计开发了FBG磁场传感装置,验证了FBG传感装置用于气隙磁通密度测量的可行性。构建了磁力轴承FBG气隙磁通密度在线测量系统,实现气隙、转速、线圈电流的调节,模拟磁力轴承的工作状态。在转子静止和旋转两种状态下,使用FBG磁场传感装置测量了不同线圈电流、不同气隙和不同转速条件下的磁力轴承气隙磁通密度,实测结果与有限元计算结果对比分析表明,在转子静止和旋转两种状态下,FBG传感装置对气隙磁通密度的测量均达到了一定的准确性。更多还原

【Abstract】 Magnetic bearing(MB) is a kind of electromechanical device with mutual conversion between electromagnetic energy and mechanical energy.MB’s basic performance is represented essentially by electromagnetic field features.Magnetic material’s nonlinear magnetic permeability and saturation,magnetic leakage, magnetic coupling,eddy current effect and etc make MB’s electromagnetic field present fundamentally nonlinearities.It is significant to make researches on MB’s electromagnetic field with theory calculation and measurement for MB’s performance improvement.For MB’s two typical working states,electromagnetic field potential equations are derived and boundary conditions are defined for an eight-pole radial MB.Finite element method(FEM) is utilized to solve the electromagnetic field equations.For rotor suspension,static electromagnetic field distribution is calculated through 3D FEM with consideration of nonlinearities mentioned above.Calculation results show that MB’s key performance parameters--air gap magnetic flux density and magnetic forces are affected by the nonlinearities apparently.A radial MB static electromagnetic field measurement platform is constructed and a three channel Guassmeter is utilized to measure the magnetic flux density distribution.The 3D FEM model is modified by the measurement results and achieves certain accuracy.For rotor rotation,magnetic flux distribution,air gap magnetic flux density, suspension force,drag force and power loss of MB are calculated through 2D nonlinear FEM under different coil current and rotating speed conditions.Results show that rotor material’s magnetic saturation induces saturation in air gap magnetic flux density and drag force,and the saturation points are determined by both coil current and rotating speed.To solve air gap magnetic flux density online measurement problem,it is introduced to apply Fiber Bragg Grating(FBG) in magnetic flux density measurement. A novel FBG electromagnetic field sensing device is designed and fabricated,and its feasibility in air gap magnetic flux density measurement is verified.A FBG-based air gap magnetic flux density online measurement system is established,which realizes air gap,rotor speed and coil current adjustments to simulate MB working states.Air gap magnetic flux density is measured through the FBG electromagnetic field sensing device under different coil current,air gap and rotating speed conditions when the rotor is static or rotating.Comparison results between measurement and FEM calculation show that air gap magnetic flux density measurement through FBG electromagnetic field sensing device achieves certain accuracy. Key words:Magnetic bearing(MB);electromagnetic field;Finite element method(FEM);Fiber Bragg Grating(FBG);magnetic flux density更多还原