新型磁悬浮转子系统的专家PID控制研究

介绍一种新型磁悬浮轴承的工作原理,并且利用动力学和电磁学原理建立磁悬浮轴承系统的数学模型,讨论了刚度阻尼和控制系统的关系,通过此关系确定了常规PID的控制参数。利用常规PID的3个参数作为专家PID控制器的初始参数设计了专家PID控制器,并在磁悬浮轴承平台上进行了实验。实验结果证明此新型磁悬浮轴承控制系统在专家PID控制器的作用下能够快速、稳定悬浮,性能良好。     

主动磁悬浮轴承支承旋转机械的减振性能研究

针对旋转机械的振动噪声问题,在对轴承工作特性及系统振动传递特性进行理论分析的基础上,提出了采用新型主动磁悬浮轴承取代传统机械轴承以实现整机减振降噪的设想.以某工程试验样机为研究对象,利用有限元软件考察了轴承的刚度变化对该样机轴承座机脚振动不平衡响应的影响,进而开展了专门的振动对比实验来对主动磁悬浮轴承的减振性能进行实际评估.结果表明:减小轴承刚度的思路对于降低旋转机械的机脚振动确实可行;相比于机械轴承,采用主动磁悬浮轴承支承对于减小整机振动水平具有显著实际效果.相关结论可为拓展主动磁悬浮轴承技术的应用领域和场合提供重要思路及数据支持,同时也为其今后的工程化实用奠定研究基础.     

磁悬浮轴承-转子系统非线性行为的控制

利用状态反馈法,对磁悬浮轴承-转子系统的振动进行控制。通过理论推导,证明了在原点附近,可近似的将受控系统分解为两个渐近稳定的子系统之和。借助数值仿真对转子受控前后的运动响应进行分析,以验证该控制方案的有效性。通过比较发现,提出的状态反馈控制方案不但能控制转子的周期运动,而且对该系统的概周期运动和混沌运动也能进行有效控制     

关于压缩机防喘振控制的探讨

离心压缩机的“喘振”现象是压缩机在运行过程中出现的一种异常状态,喘振发生后会严重干扰压缩机机组的正常运行,甚至损坏机组设备,引起恶性事故,因此必须进行有效的防喘振控制。喘振的发生除了和压缩机组自身的性能有关外,还与和压缩机组相联接的管网有着十分密切的关系。该文主从压缩机与管网的性能关系方面对喘振的产生原因与防喘振控制做了一些探讨和分析。     

浅析离心式压缩机防喘振控制

中国石油大庆石化公司120万吨乙烯改扩建工程,裂解气压缩机EC-3301为日本三菱重工有限公司(MHI)成套设计制造,由蒸汽透平驱动、离心式五段压缩、三个缸体组成。本文主要针对离心式压缩机防喘振控制进行简要分析。     

三级离心式空压机的防喘振控制

本文介绍了离心式空压机的防喘振控制流程,方法和实际操作经验,可供同行参考。     

传感器冗余的磁悬浮轴承转子系统研究

构建了传感器冗余的磁悬浮轴承转子系统,建立了基于ADAMS和MATLAB的系统五自由度仿真模型,并进行了联合仿真,分析了系统运行过程中传感器位置的改变对系统动态性能的影响。编写了基于TMS320F28335 DSP的不完全微分PID和模糊PID控制程序,设计了传感器故障诊断方法,通过人为切断某一传感器的方式在试验台上进行了试验验证。研究结果表明,在转子运行过程中,某一传感器失效后,系统仍能安全稳定地运行。     

电磁悬浮飞轮转子系统的模态解耦控制

基于电磁悬浮飞轮转子系统的数学模型,首先提出了一种在高速下能够使电磁悬浮飞轮转子系统保持稳定运行的模态解耦控制方法,然后对这种方法的解耦效果以及控制的有效性进行了仿真分析,并与传统分散PD控制的性能进行了比较。结果表明提出的模态解耦控制方法可以实现对电磁轴承飞轮转子系统的转动模态和平动模态间的解耦,以达到对各个模态的刚度和阻尼进行独立调节,使电磁悬浮飞轮转子系统具有更好的动态性能和更强的抗干扰能力的目的。     

中低速磁悬浮交通中轨排安装质量控制

本文针对中低速磁悬浮交通中轨排安装的特点,通过对轨排安装质量影响因素的分析,在容易出现质量问题的关键环节采取相应的控制预防措施,控制了轨排安装质量,为下道工序及整项工程顺利进行创造了条件。     

Application of the preview compensation control method to large gap control in hybrid magnetic suspension

ABSTRACT

Large-gap magnetic suspension is a conceptual design for experiments which can be used to investigate technical issues associated with magnetic suspension and accurate suspended-load control for large gaps. The traditional linear control strategy has significant limits to its control area, usually around the chosen operating points. With increase in the suspension gap, the nonlinearity and time delay of a system will become more serious. Additionally, the interaction of an estimation scheme and corresponding controller has not been fully examined in the literature. This paper examines a developed compound control method, Smith forecast compensation control with proportional-integral-derivative control (PID control) , as a means of advancing the achievable performance of magnetic suspension. We designed and built a laboratory testbed to determine the feasibility of utilizing proposed methods in these types of applications. The analytical results are supported by the simulations and experiments, showing our research approach to be fairly successful at providing satisfactory performance for motion control under conditions involving a large air gap.     

磁悬浮支承双层隔振系统的半主动模糊隔振控制

设计了磁悬浮支承单元结构,并将其应用于双层隔振系统中。根据该结构和磁悬浮支承与双层隔振的特征,建立了半主动输出反馈的模糊控制器,通过调节磁悬浮支承单元的电流,改变磁力从而获得系统的最佳刚度。仿真分析该半主动控制双层隔振系统与最优被动双层隔振系统在相同复杂信号激励下输出力曲线。另外,还仿真分析了在冲击激励下,系统的输出力曲线。结果表明,半主动输出反馈模糊控制下的磁悬浮支承双层隔振系统的隔振效果与抗冲击特性优于常规最优被动隔振。     

基于模型设计方法的混合磁悬浮平台的控制设计及实现

基于模型的设计方法,利用Matlab/Simulink对磁悬浮系统进行浮点数字PID控制仿真,并结合定点控制器DSP2812,实现系统控制的快速构建,达到系统模型及控制设计、系统仿真和硬件实现的无缝集成,从而加速控制系统的快速开发.首先,在Matlab/Simulink环境中建立系统控制模型,并利用其自带的定点工具箱对数字控制器进行定点化处理,建立可以移植的带有数字平均滤波的Simulink代码模型.再通过RTDX功能进行算法的调试与验证,并进行代码模型的优化.最终自动生成可靠的C代码到控制器来实现对混合磁悬浮平台的控制,实现在模型仿真和系统实施的集成和统一.并由实物进行了验证．     

基于预瞄技术的汽车磁流变半主动悬架控制方法

在综合利用磁流变减振器控制电流与输出阻尼力的关系、以及轴距预瞄控制技术的基础上,提出汽车磁流变半主动悬架预瞄控制方法,通过理论分析和计算机仿真,研究在不同行驶速度下汽车磁流变半主动悬架动态性能,实验表明,该法具有提高悬架系统的控制性能,使悬架承受的冲击响应小、振动强度低和汽车行驶平顺性好等特点.     

Flow regimes of a fluid driven granular suspension

We discuss molecular dynamics simulations of a granular suspension driven in a channel by an embedding fluid. The flow has three different regimes: it is disordered at small packing fractions, ${\phi}$ ; above a transition point, ${\phi_m}$ , flows becomes ordered in layers, but only in a fraction of samples; at higher ${\phi}$ , if ordering is avoided, jamming is also encountered. In the disordered flow regime the velocity profile is power law, consistent with an Ostwald-de Waele constitutive relation. In the ordered regime, flow is concentrated in the bulk in a nearly solid plug having a flat velocity profile, with narrow shear regions at the boundaries. Interestingly, velocity fluctuations are approximately linear in the velocity in all regimes.     

Properties of magnetic fluid particles

Very fine particles of magnetite, nickel ferrite, and cobalt ferrite were produced by grinding coarser powders in a ball mill with a carrier fluid and a surfactant. The particles were examined by means of chemical analysis, electron microscopy, x-ray diffraction, magnetic measurements, and Mössbauer spectroscopy. Properties were determined before and after removing the surfactant coating. The most significant observation was that in some systems a large fraction of the spins was pinned in extremely high anisotropy fields as a result of bonding to the surfactant molecules. Anomalous magnetic hysteresis behavior was also noted when the surfactant coating was present.     

高速永磁电机机组轴系振动研究

高速电机由于体积小、功率密度大和效率高等优点,符合节能减排经济发展需要,成为电机领域的研究热点之一。在高速旋转机械中,转子振动将逐渐成为制约电机正常运行的瓶颈。因此,研究电机的振动特性对于电机的高速可靠运行是非常必要的。电机转子振动的来源主要包括偏心产生的离心力和不平衡磁拉力,采用有限元及Newmark积分法计算转子在不平衡力作用下非线性不平衡响应,用样机振动实验验证计算方法的正确性,通过机组振动实验分析轴系振动产生的原因。研究表明,电机的振动主要为离心力产生基频振动及由于转子动偏心产生的10倍频不平衡磁拉力的振动;其次是2倍频的振动。根据振动产生的主要原因提出相应减小振动的措施。     

Supercritical fluid processing of drug nanoparticles in stable suspension

Significant effort has been directed toward the development of drug formulation and delivery techniques, especially for the drug of no or poor aqueous solubility. Among various strategies to address the solubility issue, the reduction of drug particle sizes to the nanoscale has been identified as a potentially effective and broadly applicable approach. Complementary to traditional methods, supercritical fluid techniques have found unique applications in the production and processing of drug particles. Here we report the application of a newly developed supercritical fluid processing technique, Rapid Expansion of a Supercritical Solution into a Liquid Solvent, to the nanosizing of potent antiparasitic drug Amphotericin B particles. A supercritical carbon dioxide-cosolvent system was used for the solubilization and processing of the drug. The process produced well-dispersed nanoscale Amphotericin B particles suspended in an aqueous solution, and the suspension was intrinsically stable or could be further stabilized in the presence of water-soluble polymers. The properties of the drug nanoparticles were found to be dependent on the type of cosolvent used. The results on the use of dimethyl sulfoxide and methanol as cosolvents and their effects on the properties of nanosized Amphotericin B particles are presented and discussed.