双框架磁悬浮控制力矩陀螺磁轴承负载力矩复合补偿的控制

提出一种基于角速率前馈与力矩观测相结合的磁轴承负载力矩复合补偿控制方法来提高双框架磁悬浮控制力矩陀螺磁悬浮转子的悬浮精度。建立了双框架磁悬浮控制力矩陀螺磁悬浮转子动力学模型,分析了内外框架转动情况下的磁轴承负载力矩。分别基于框架角速率前馈和力矩观测设计了磁轴承负载力矩复合补偿控制方法,分析了补偿后系统的稳定性。最后,利用实验室研制的样机搭建试验平台对本文所提出的方法进行了实验验证。结果表明:在框架以角加速度120(°)/s2启动至10(°)/s时,该方法使转子Ax端位移跳动量减小为未补偿前的44.8%;内外框架以幅值频率10Hz正弦激励时,转子Ax、By端的位移跳动量分别减小为未补偿前的23.4%和35.5%。结果显示提出的方法有效地提高了磁悬浮转子在负载力矩扰动下的悬浮精度。     

磁悬浮控制力矩陀螺磁轴承的变工作点线性化自适应控制方法

为提高磁悬浮控制力矩陀螺框架高速时的磁悬浮转子系统稳定性,研究磁轴承的电磁力-线圈电流/转子位移非线性的线性化及其控制方法.分析框架转动时的磁轴承工作点变化规律,提出磁轴承力-电流/位移特性基于框架转速的变工作点大范围线性化方法,根据线性化得到的线性变参数模型设计增益调节与前馈控制相结合的控制律,按照框架转速的大小对磁轴承位移刚度的变化进行自适应补偿,在磁悬浮转子稳定前提下使框架转速由6.25(°)/S提高到9.5(°)/S.该方法能有效补偿框架运动时的磁轴承力非线性,大幅提高框架转速较高时的磁悬浮转子系统稳定性.     

动力磁悬浮轴承原理

基于普通的径向磁悬浮轴承 ,研究定子绕组由产生旋转偏磁磁场的绕组和产生旋转控制磁场的绕组叠加的动力磁悬浮轴承的工作原理。在两种绕组的极数相差 2极时 ,动力磁悬浮轴承除产生支承转子的径向轴承力外 ,还产生驱动转子转动的力矩     

提高双框架磁悬浮CMG动态响应能力的磁轴承补偿控制方法与试验研究

针对高动态响应双框架磁悬浮控制力矩陀螺对高速转子悬浮精度的影响,分析磁悬浮高速转子与内、外框架非线性耦合特性,建立内外框架转动时的高速转子动力学模型.该模型在原有陀螺力矩的基础上兼顾转动惯性力矩,考虑到转动惯性力矩中框架角加速度变量在测量过程中存在的不确定干扰和噪声,采用鲁棒H(滤波对内外框架角加速度进行滤波估计;在此基础上,根据力矩补偿控制策略,利用磁轴承控制系统驱动线圈产生相应的电磁力,对转动惯性力矩和陀螺力矩进行补偿控制.试验结果表明,H(滤波对于噪声的不确定性具有良好的鲁棒性,磁悬浮高速转子跳动量减至补偿前的30%以内,提高了磁悬浮系统的稳定性和悬浮精度,改善了控制力矩陀螺的力矩输出特性.     

惯性稳定平台用球面洛伦兹轴承

为克服现有惯性稳定平台姿态补偿力矩带宽低、偏转角小的缺陷,提出了一种基于洛伦兹轴承的惯性稳定平台,介绍了其结构、工作原理和球面洛伦兹轴承方案.采用等效磁路法建立并分析了洛伦兹轴承的数学模型,得到了其径向偏转电流刚度.综合考虑气隙磁密均匀性和偏转刚度,对球面洛伦兹轴承进行参数设计,并通过有限元法对洛伦兹轴承进行电磁分析.结果 显示,绕组区域最大和最小气隙磁密分别为0.336 T和0.318 T,气隙磁密变化率为5.6％.基于设计参数,绘制了惯性平台不同角度下偏转刚度曲线,得到了平台不同工作状态下的控制带宽.     

磁悬浮陀螺飞轮用隐式洛伦兹力磁轴承

针对磁悬浮陀螺飞轮用显式洛伦兹力磁轴承气隙磁密均匀性差的问题,提出了一种磁钢内置的隐式洛伦兹力磁轴承,并采用三维有限元法对两种方案的气隙磁密进行比较分析。隐式方案的气隙磁密在周向和纵向的变化率分别为0.8%和8.4%,远优于显式方案的15.0%和23.7%。利用磁场分割法对隐式方案的磁阻进行了区域分割,采用积分法精确计算各区域磁阻,建立了磁轴承磁路数学模型,得到了影响偏转电流刚度的关键结构参数,并基于有限元法对隐式方案形状及结构参数进行详细优化。结果表明,在不恶化气隙磁密变化率的前提下,优化前后绕组区域的最大磁密和最小磁密分别从0.404T和0.368T增加至0.464T和0.427T,增幅为14.6%和16.0%。根据优化结果研制了一台隐式洛伦兹力磁轴承,并进行了气隙磁密和偏转电流刚度实验测试,测试结果与设计结果相符,对洛伦兹力磁轴承的设计具有重要意义。     

基于滑模扰动观测器的磁轴承主动振动控制

由于磁悬浮控制力矩陀螺转子的不平衡振动会造成控制力矩陀螺系统的同频扰动,影响卫星姿态控制精度与卫星载荷精度,本文提出了基于滑模变结构扰动观测器的磁轴承主动振动控制方法.首先,对不平衡扰动力和力矩作用下的磁轴承-转子系统进行建模;接着,设计了滑模变结构扰动观测器观测不平衡扰动力和力矩;然后,利用跟踪微分器估计位移传感器输出信号的微分获取速度信号,降低观测器的阶数;最后,将滑模扰动观测器的输出引入磁轴承控制器,对观测得到的同频不平衡扰动力和力矩进行补偿.仿真和试验结果均表明,设计的滑模变结构观测器实现了对不平衡扰动的观测,通过控制器有效地实现了对不平衡扰动的补偿,减少了72％的同频振动.     

磁悬浮转子系统耦合特性测试方法及测试台的设计

磁悬浮转子系统中，根据磁力轴承工作原理，径向磁力轴承内存在力耦合、磁耦合；径向磁力轴承之间存在力耦合、力矩耦合。这些耦合现象对磁悬浮转子系统的结构设计、系统建模和控制系统的设计都有影响。在对磁悬浮转子系统耦合特性研究的基础上，提出了磁悬浮转子系统耦合特性测试的实验方法。并且提出了相应测试实验台的设计方案。     

非线性强陀螺效应磁悬浮转子的解耦控制

针对磁悬浮控制力矩陀螺径向磁悬浮转子强非线性、强陀螺效应耦合对系统稳定性的影响,建立了磁悬浮转子多通道非线性动力学模型与功放模型,分析了磁悬浮转子系统的强陀螺效应耦合性,提出了一种考虑功放环节的α逆系统结合滑模控制器的解耦控制方法,并对其进行了仿真试验。结果表明,该方法对磁悬浮转子系统有良好的解耦效果与鲁棒性。     

五自由度全永磁轴承系统的稳定悬浮特性分析

为探讨永磁悬浮轴承系统的稳定悬浮特性,从轴承刚度角度对五自由度全永磁轴承系统的稳定悬浮特性进行了分析。采用等效磁荷理论建立永磁轴承的承载力、承载力矩和刚度的数学表达式,并利用蒙特卡洛法对表达式中存在的四重积分进行求解。探究转子在受迫进动情况下以及受到外力矩干扰时继续保持稳定旋转所需要的最低临界转速。基于轴向永磁轴承与径向永磁轴承的结构,提出一种六磁环五自由度全永磁轴承系统结构模型,对全永磁轴承的转子系统承受轴向和径向外载荷的承载力、力矩和承载刚度进行分析,得出轴向可以承受外载荷而径向无法承受外载荷,即静态下轴向可以稳定悬浮、径向不能稳定悬浮,符合Earnshaw定理。利用刚性转子的陀螺惯性力矩来承受全永磁轴承系统的不平衡力矩和外力矩,从而保持转子定轴自稳定悬浮,并对系统稳定悬浮特性进行计算,结果表明转子在超过最低临界转速后是可以实现动态稳定悬浮的,具有一定的工程应用价值。     

箔片式动压止推气体轴承的发展

本文简要回顾了箔片式动压止推气体轴承的发展历史.详细介绍了箔片式动压止推气体轴承的主要类型及研究状况.     

一种新型的气体静压支承

本文介绍了一种新型的气体静压支承的结构及其设计方法。此种气体静压支承具有设计计算简便,加工容易、制造成本低,承载能力高、刚性好、能同时承受两个方向载荷等优点。具有很好的工程应用前景,可广泛应用于摩擦力测量试验台、机床导轨等。     

Dynamic Characteristics and Stability Analysis of a Wavy Thrust Bearing

A numerical procedure to analyze wavy thrust bearings is described. The numerical model is developed by assuming that two circular plates rotate relative to each other. The upper plate is assumed to be flat and rotating, whereas the lower plate is assumed to be stationary and wavy in surface geometry. A Reynolds-equation-based procedure is used to simulate the dynamics engendered by various wavy geometries and loading conditions. The equilibrium position of the journal results from the equilibrium between the forces generated by the fluid-film pressures and the externally applied loads. A numerical small perturbation technique is applied to calculate the linear stiffness and damping characteristics of the bearing at the equilibrium position. Using a three-degrees-of-freedom system with one axial and two rotational displacements, nine linear stiffness coefficients (three principal and six cross-coupled coefficients) and nine linear damping coefficients are calculated. These linear coefficients are then used to calculate the eigenvalues of the system by solving the homogeneous equations of motion. The stability of the bearing system is then expressed using the lowest logarithmic decrement obtained from these eigenvalues. Using this procedure, a parametric study is carried out to examine the effects of external load, location of the applied load, bearing number, and bearing wave amplitude on journal equilibrium position, bearing linear stiffness, damping characteristics, and bearing stability.     

The Experimental Study of Aerodynamic Plate-Foil Journal Bearings for High Speed Cryogenic Turboexpander

Experiments have been conducted on the application of a new type of gas lubricated self-acting journal bearing—plate-foil bearing to a high speed cryogenic turboexpander. The 25.0 mm diameter bearing consists of a rigid housing and a flexible foil element; different structure parameters of the bearing are selected in the experiments. Experimental results indicate the foil bearing presented here offers better system stability performance and high durability, and it confirmed that the application of this type of plate-foil bearing to the cryogenic turboexpander is feasible. The experiment results, including the effect of the plate-foil bearing structure parameters on the rotor-bearing system stability, are described in this paper.     

箔片式动压径向气体轴承的发展

本文简要回顾了气体轴承和箔片式动压径向气体轴承的历史及国内、外目前的研究状况。详细介绍了箔片式动压径向气体轴承的起源、结构形式、应用范围和理论、实验及应用研究的发展,并提出了一种新型结构形式的弹性支承箔片动压径向气体轴承。     

平箔动压止推气体轴承的试验研究

本文提出了一种新型结构的箔片止推动压气体轴承，搭建了多功能止推轴承试验台，并主要针对其承载力性能进行了初步的试验研究，试验轴承的外径为φ38mm，内径为φ16mm，在11000r/min的转速下获得的最大轴向承载力为44.1N。     

An Experimental Investigation into the Temperature Profile of a Compliant Foil Air Bearing

A series of tests was performed to determine the internal temperature profile in a compliant bump-type foil journal air bearing operating at room temperature under various speed and load conditions. The temperature profile was collected by instrumenting a foil bearing with nine type-K thermocouples arranged in the center and along the bearing's edges in order to measure local temperatures and estimate thermal gradients in the axial and circumferential directions. To facilitate the measurement of maximum temperatures from viscous shearing in the air film, the thermocouples were tack-welded to the backside of the bumps that were in direct contact with the top foil. The mating journal was coated with a high-temperature solid lubricant that, together with the bearing, underwent high-temperature start-stop cycles to produce a smooth, steady-state run-in surface. Tests were conducted at speeds from 20 to 50 krpm and loads ranged from 9 to 222 N.

The results indicate that, over the conditions tested, both journal rotational speed and radial load are responsible for heat generation with speed playing a more significant role in the magnitude of the temperatures. The temperature distribution was nearly symmetric about the bearing center at 20 and 30 krpm but became slightly skewed toward one side at 40 and 50 krpm. Surprisingly, the maximum temperatures did not occur at the bearing edge, where the minimum film thickness is expected, but rather in the middle of the bearing, where analytical investigations have predicted the air film to be much thicker. Thermal gradients were common during testing and were strongest in the axial direction from the middle of the bearing to its edges, reaching 3.78° C/mm. The temperature profile indicated the circumferential thermal gradients were negligible.     

Thermal Management Techniques for Oil-Free Turbomachinery Systems

Tests were performed to evaluate three different methods of utilizing air to provide thermal management control for compliant journal foil air bearings. The effectiveness of the methods was based on bearing bulk temperature and axial thermal gradient reductions during air delivery. The first method utilized direct impingement of air on the inner surface of a hollow test journal during operation. The second, less indirect method achieved heat removal by blowing air inside the test journal parallel to the shaft axis to simulate air flowing axially through a hollow shaft. The third method emulated the most common approach to removing heat by forcing air axially through the bearing's support structure. Internal bearing temperatures were measured with three type K thermocouples embedded in the bearing that measured general internal temperatures and axial thermal gradients. Testing was performed in a 1 atm, 260°C ambient environment with the bearing operating at 60 krpm, and supporting a load of 222 N. Air volumetric flows of 0.06, 0.11, and 0.17 m³/min at approximately 150 to 200°C were used.

The tests indicate that all three methods provide thermal management but at different levels of effectiveness. Axial cooling of the bearing support structure had a greater effect on the bulk temperature for each air flow and demonstrated that the thermal gradients could be influenced by the directionality of the air flow. Direct air impingement on the journal's inside surface provided uniform reductions in both bulk temperature and thermal gradients. Similar to the direct method, indirect journal cooling had a uniform cooling effect on both bulk temperatures and thermal gradients but was the least effective of the three methods.     

陀螺电机轴连轴承生热分析

基于摩擦学理论,对轴连轴承组件生热进行了研究.针对轴连轴承组件的具体工况及结构特点,分析了轴连轴承组件的发热机理,建立了轴承组件内各部分功率损失计算模型,在此基础上得出了轴承总的生热和轴承各单元间的局部生热.以某型陀螺电机轴连轴承为例分析了不同工作转速和工作载荷对轴承总生热和各单元局部生热的影响.结果表明,轴承转速、轴...     

径向小孔静压气体轴承的试验研究

本文对多排小孔静压气体径向轴承的静、动特性及稳定性进行了研究，将试验数据与理论结果和中压透平膨胀机气体轴承运行数据进行了对比，并分析了影响轴承性能的各种因素。