风力发电机磁轴承参数设计及控制系统研究

为减小风力发电机的机械摩擦及减少其维护成本,降低风力发电机启动风速,减小旋转阻力矩,提高风能利用率,在垂直轴风力发电机中采用混合轴承支承,即风力发电机径向采用1个径向磁轴承和1个机械轴承支承,轴向采用一个轴向磁轴承来实现五自由度支承。针对轴向磁轴承,首先介绍了其结构及工作原理,然后采用等效磁路法建立数学模型,并按性能指标要求进行参数设计,然后用Ansoft软件对轴向磁轴承磁场及受力等进行分析验证,设计了轴向磁轴承控制系统,并用Matlab软件对磁轴承的控制系统进行了阶跃响应、起浮和扰动等仿真研究。研究结果表明:参数设计合理,控制系统够实现磁轴承可靠及稳定的悬浮。     

支承高速电机的混合磁轴承结构参数设计与分析

提出了一种5自由度混合磁轴承支承高速电机系统,由径向2自由度混合磁轴承、径向-轴向3自由度混合磁轴承和高速电机构成.2自由度磁轴承定子采用8极结构,4个是控制磁极,4个是嵌入永磁体的永磁磁极.3自由度混合磁轴承集成了径向和轴向轴承功能,采用径向充磁的环形永磁体提供径向和轴向磁轴承偏置磁场.文中介绍了混合磁轴承的结构和工作原理,导出了磁轴承的数学模型,给出了详细的参数设计方法,最后采用MAXWELL电磁场有限元分析软件对磁轴承的磁路和主轴受力情况进行了分析.理论研究和有限元分析表明:这种5自由度磁轴承系统结构参数设计合理.     

推力磁轴承的力学特性及其对径向磁轴承的影响

讨论了计入推力盘静态倾斜影响后的推力磁轴承的力学特性,导出了其静、动特性的系数公式,并结合某涡轮膨胀机的推力磁轴承进行了实例计算。结果表明,推力盘的静态倾斜对推力磁轴承的力学特性产生显著影响,并改变径向磁轴承的静负荷分配,使得推力磁轴承与径向磁轴承之间产生强烈的耦合作用。该结果可用于5自由度磁悬浮轴承－转子系统的机电耦合动力学研究。     

永磁轴承的刚度研究

永磁轴承具有结构简单、无磨损等优点,可以与机械轴承或电磁轴承结合构成各种磁轴承系统.利用永磁体等效电流模型,以涡轮分子泵永磁轴承为对象建立刚度矩阵,由尺寸参数对各刚度的影响分析可知:磁环横截面为正方形时,径向刚度和耦合刚度最大;倾斜剐度的正负在正方形横截面处发生变化.     

三支承磁悬浮轴承的不对中特性

应用多个磁悬浮轴承支承的转子系统,由于机械加工以及安装等方面的误差会导致各个磁悬浮轴承之间有一定的不对中量。提出了将转子偏离磁轴承中心悬浮,以减小各个支承悬浮位置的不对中量;结合单自由度磁轴承控制原理,分析了转子悬浮位置偏离中心对磁轴承悬浮性能的影响;从理论和试验两个方面对比研究了3个不对中磁悬浮轴承支承的转子悬浮在磁轴承中心和偏离中心后磁轴承的控制电流和抗扰动性能。研究结果表明一定程度的偏离磁轴承中心悬浮能够提高磁悬浮轴承系统的稳定性。     

直驱风力发电机径向-轴向混合磁轴承设计及分析

为解决或降低传统直驱风力发电机系统的机械摩擦问题,以有效提高风能利用率,提出直驱风力发电机采用机械轴承和磁悬浮轴承集成支承技术,即采用机械轴承和径向-轴向三自由度混合磁轴承实现直驱风力发电机的集成支承。针对径向-轴向三自由度混合磁轴承,采用等效磁路法进行数学建模,并利用有限元分析软件对其进行参数设计与机理分析。在此基础上,构建了径向-轴向三自由度磁轴承试验平台,试验结果证明设计的径向-轴向三自由度磁轴承能够实现稳定悬浮。     

叠片铁芯式轴向冗余磁悬浮轴承的设计

由于无法采用硅钢片叠片结构,传统两环轴向冗余磁悬浮轴承定子通常采用电工纯铁整体式结构,为克服整体式结构在工作时会产生较大涡流损耗和温升的问题,提出了叠片铁芯式轴向冗余磁悬浮轴承,介绍2种冗余磁悬浮轴承的结构,对比了两环轴向冗余磁轴承和叠片铁芯式轴向冗余磁轴承的承载力和温升性能。结果表明,叠片铁芯式轴向冗余磁轴承的承载力和温升均有明显的优势。     

浙江飞旋成功研发磁轴承

<正>浙江飞旋科技有限公司研发成功"基于交叉反馈控制的FS450型分子泵磁轴承",这是第一个国产磁轴承产品,磁轴承又称主动磁悬浮轴承,是一种转子与定子之间没有机械接触的新型高性能轴承。它由机械部件、电控系统、传感器和辅助轴承等构成。利用电磁力作用将转子悬浮于空间,具有无机械磨损、降耗低、允许转速高、噪声少、寿命长、无润滑介质等     

磁悬浮轴承研究现状及其发展

按照磁轴承的应用发展需求对磁轴承的最新研究进展进行了阐述,通过比较不同及同类别磁轴承的优劣及典型建模方法,对影响磁轴承系统性能的两大关键问题——结构和悬浮力建模方法进行了较为全面的概述,研究了磁轴承系统的未来发展,提出了多种结构形式及控制策略的磁轴承系统,功耗低、高速高精、高性能、高可靠性的磁轴承将是未来研究的主要方向。     

单片DLP色轮采用磁轴承支承的研究

阐述了单片DLP投影机色轮运行和磁轴承的基本原理,对磁轴承技术在色轮驱动系统的应用进行了研究,采用一个主动型轴向磁轴承和两个被动型径向磁轴承来实现色轮转子的五自由度悬浮.基于色轮转子的重量与转速,设计出了磁悬浮轴承的参数,并利用有限元分析软件ANSYS对设计结果进行了仿真.     

磁悬浮风力发电机用锥形被动磁轴承分析与设计

为从根本上解决传统风机轴承的机械摩擦问题以有效提高风能利用率,提出了主、被动相结合的风力发电机全磁悬浮支承方案,在对小型水平轴磁悬浮风机轴承系统受力特性分析的基础上,将锥形被动磁轴承作为轴向轴承,利用有限元法分析了其力学特性,并在空间限定的情况下以刚度最大为优化目标对永磁体的尺寸、环数等进行了优化设计,最后给出了锥形被动磁轴承的实例设计结果。     

Current Status of Hybrid Bearing Damage Detection

Advances in material development and processing have led to the introduction of ceramic hybrid bearings for many applications. The introduction of silicon nitride hybrid bearings into the high-pressure oxidizer turbopump on the space shuttle main engine led NASA to solve a highly persistent and troublesome bearing problem. Hybrid bearings consist of ceramic balls and steel races. The majority of hybrid bearings utilize Si₃N₄ balls. The aerospace industry is currently studying the use of hybrid bearings and, naturally, the failure modes of these bearings become an issue in light of the limited data available.

In today's turbine engines and helicopter transmissions, the health of the bearings is detected by the properties of the debris found in the lubrication line when damage begins to occur. Current oil debris sensor technology relies on the magnetic properties of the debris to detect damage. Because the ceramic rolling elements of hybrid bearings have no metallic properties, a new sensing system must be developed to indicate the system health if ceramic components are to be safely implemented in aerospace applications. The ceramic oil debris sensor must be capable of detecting ceramic and metallic component damage with sufficient reliability and forewarning to prevent a catastrophic failure.

The objective of this research is to provide a background summary on what is currently known about hybrid bearing failure modes and to report preliminary results on the detection of silicon nitride debris in oil using a commercial particle counter.     

Non-contact position control via fluid shear force

Non-contact position control of components is beneficial to avoid wear, damage, and nonlinearities associated with friction. Air bearings, in particular, offer non-contact, high stiffness guidance, but no means of controlling the position of the supported component. In this work, we investigate the use of shear force resulting from the air bearing fluid flow as a means of actuation. Shear force actuation is tested in an air bearing slumping system, where a flat, horizontally placed glass substrate is supported on both sides by top and bottom air bearings. We investigate the use of two methods of substrate position sensing: a fiber-optic sensor and a machine vision sensor. We show that the glass substrate position can be successfully controlled by using fluid shear force. The magnitude of the fluid shear force is measured. System identification is performed, and the results are shown to agree with a second-order model.     

Determination of magnetic flux density on the surfaces of rolling-element bearings as an indication of the current that has passed through them—an investigation

This paper introduces a theoretical model to determine the developed magnetic flux density on the inner and outer surfaces of the inner race and outer race, and on the surface of rolling-elements of a rolling bearing operating under the influence of an electric current. The flux density, analytically determined, is compared with that of the flux density developed on the surfaces of races and rolling-elements of bearings tested on the bearing test-up under the influence of an electric current. The magnetic flux density on the surfaces of damaged bearings of motors and alternators has also been measured and the theoretical model is used to determine the amount of current flow through the damaged bearings. The current flow through the bearings, thus established, has been compared with that of the current evaluated by the measurement of shaft voltage and bearing resistance. The model has the potential to ascertain the cause of failure by current passage and to establish the amount of flow of leakage current through the bearings by determining the magnetic flux density on the surfaces of rolling-element bearings. The current flow, thus established, together with the measurement of the shaft voltage, allow the bearing impedance to be established.     

大型汽轮发电机组轴系稳定性研究

本文建立了大型汽轮发电机组轴系稳定性的基本方程,轴承类型可以全部是固定瓦或可倾瓦轴承,也可以是固定瓦和可倾瓦轴承的组合。对某国产300W汽轮发电机组的稳定性进行了数值计算,提出了轴系集中质量合理划分的原则。用本文提出的方法和J. W. Lund法研究了一台以可倾瓦轴承为支承的离心压缩机组的稳定性,结果表明后者与实际情况相差较大。     

Dynamic stability experiments of compliant foil thrust bearing with viscoelastic support

In order to reduce the complexity of machine construction and improve the mechanical efficiency, high speed rotation machineries usually implement self-acting gas bearings to substitute the traditional oil-lubricated bearings. This paper presents test results of a gas thrust bearing with viscoelastic support which is designed for high speed turbo-machinery. The gas bearing, which belongs to compliant foil bearings, consists of a top thin metal foil and a bottom thin rubber foil. Static and stability experiments are conducted on a high speed gas turbine test rig. The static results indicate that the structural stiffness of test bearing generally increases with the increase in axial load and the decrease in thickness of bottom foil. In the rotation tests, rotor runs stably with small vibration amplitude, which is dominant in waterfall plot during whole speed up procedure. It shows that test bearing has preferable stability characteristics for high speed gas turbines.     

飞轮储能磁轴承系统结构及其悬浮特性

介绍了一种由径向永磁轴承与电磁推力轴承组成的单轴主动控制的飞轮储能磁轴承系统结构 ,径向永磁轴承提供径向恢复力与轴向悬浮力 ,电磁推力轴承提供轴向恢复力。并对系统的结构参数计算及其磁悬浮特性进行了分析与讨论。研究结果表明 ,永磁轴承动、静磁环轴向位移对系统承载力与刚度有明显影响 ,采用多对磁环永磁轴承 ,有利于提高系统承载力与径向刚度     

Analysis and Design of Externally Pressurized Gas Bearings

Equations for flow rate, pressure, load, and stiffness of externally pressurized thrust and journal bearings are given for purely viscous, isothermal gas films with longitudinal or radial flow and no relative surface motion. Charts are presented by means of which the bearing characteristics can be evaluated in terms of the bearing parameter, the bearing configuration, and the ratio of supply to ambient pressure. Sample characteristics of thrust and journal bearings are established using the curves and experimental confirmation shown. A method of treating bearing films with two inlet-restricting orifices in series is described.     

Oil film thickness measurement by means of an optic lever technique

Oil film thickness in hydrodynamic bearings is a fundamental parameter influencing overall hydrodynamic bearing performance. Knowledge of this thickness allows bearing performance to be optimised. For the small hydrodynamic bearings that are usually used in laboratory test facilities, a very small sensor (e.g.,<2 mm) is required because of space limitations. Commercially available eddy‐current and capacitance sensors are too large to be mounted in the pad of such a bearing. An alternative approach is to use sensors based on optical methods, such as the optic lever technique. The main idea in this technique is to detect the intensity of a light beam reflected from a target surface. This intensity is a function of the distance between the sensor and the target. This paper reports the specific features of the optic lever technique as used for measurements of oil film thickness. The design, calibration procedure, and main characteristics of an optical sensor are discussed. A test rig for the calibration of oil film thickness sensors is also presented. The sensor response curve has two parts, linear and non‐linear; using the linear part results in high sensitivity in the micrometre range. The influence of different types of oil on the output signal of the sensor has also been investigated. Experiments with different target velocities have shown that this sensor can be used for accurate and reliable measurement of oil film thickness in hydrodynamic bearings.