磁悬浮流体机械主动叶尖间隙控制防喘振方法研究

Surge is a system-wide instability that is characterized by large amplitude oscillations in the output pressure and mass flow, which could result in serious damage to the fluid machinery. The project aiming at the fluid machinery supported by active magnetic bearings (AMBs), proposes a surge control method which can be achieved by tracking tip clearance by regulating the rotor position through the AMBs. There are several advantages for this kind of surge control method, such as no additional surge control actuator, wide working condition, lossless efficiency and quick response. Because there is the nonlinear variation of the equilibrium position of AMBs, the classical methods to build model are not sufficient. Moreover, the classical robust control methods just considering the uncertainty of controlled object models are not enough. This project proposes the method to establish an accurate system model using model updating method, and the uncertainty analysis from closed-loop stability using gap metric method is proposed for the robust surge control. The project will focus on the inherent law from control signal to fluid machinery motion, the nonlinear variation law of AMB dynamics, the relationship between tip clearance and system pressure, the uncertainty description and transition, and some basic science problem. As key technologies, the mechatronics modeling for control system, the uncertainty description, the robust control based on gap metric approach, et al., will be figured out to solve the surge control problem of AMBs fluid machinery.

喘振是流体机械在小流量工况时常发生的一种不稳定状态，严重危害机组的稳定运行。本项目针对磁悬浮流体机械，提出一种用自身的磁悬浮轴承调整转子轴向位置改变叶尖间隙防止喘振的方法，具有无需附加额外执行器，拓宽稳定运行工况范围，响应快等优点。由于此时磁悬浮轴承悬浮位置是非线性变化的，传统的建模方法不再适用；且对于这种不确定因素多的机电一体化系统，只考虑被控对象模型不确定性的传统鲁棒控制方法亦不适用。本项目提出用模型修正方法建立系统精确模型，用Gap度量方法从闭环鲁棒稳定性出发分析系统的不确定性，实现喘振控制。本项目将重点解决揭示控制信号到转子轴向位移全过程的内在规律、磁悬浮轴承特性非线性变化规律、叶尖间隙与系统压力之间的关系、不确定性在系统中的传递表征等基础科学问题，突破面向控制系统的精确机电一体化建模和不确定性描述、基于Gap度量的鲁棒控制等关键技术，解决磁悬浮流体机械不确定因素多的喘振控制难题。

喘振严重危害流体机械的稳定运行。本项目针对磁悬浮流体机械，提出一种用自身的磁悬浮轴承调整转子轴向位置改变叶尖间隙防止喘振的方法，具有无需附加额外执行器，拓宽稳定运行工况范围，响应快等优点。主要研究内容包括磁悬浮流体机械系统机电一体化建模与喘振控制仿真、轴向磁悬浮轴承鲁棒控制方法、径向磁悬浮轴承转子抗扰动控制方法、喘振信号检测、磁悬浮流体机械喘振控制工业现场实验等方面。建立了磁悬浮轴承转子系统机电一体化模型以及流体机械系统模型，得到了叶轮轴向悬浮位置变化的叶尖间隙调压模型。采用质量流量反馈控制策略，进行喘振控制仿真，仿真分析表明，喘振控制器扩展了流体机械的稳定运行范围。提出了基于V-Gap度量的轴向磁悬浮轴承H∞鲁棒控制器，解决磁悬浮轴承系统模型不确定因素多的问题。针对发生喘振时转子径向振动位移出现喘振同频干扰信号的问题，提出了基于特征模型的全系数自适应控制与扩张状态观测器联合作用的磁悬浮轴承系统控制方法，以提高径向磁悬浮轴承转子系统的抗扰动性能。分析了全系数自适应控制参数的调节规律，并给出了扩张状态观测器的抗扰动参数调节原则，通过仿真和实验验证了不同扰动信号的扰动估计与抑制效果。针对实际转子位移信号中存在直流偏置与谐波等干扰，提出了基于归一化SOGI-FLL-WPF的喘振信号检测方法。以工业中某型号磁悬浮离心式鼓风机为研究对象，进行了喘振控制实验，验证了提出基于SOGI-FLL-WPF的喘振控制方法的有效性。测试了磁悬浮离心式鼓风机的特性曲线，调整不同叶轮叶尖间隙测试了管道压力的变化，验证了改变叶尖间隙控制喘振的可行性。对磁悬浮控制器及其控制性能进行了分析，转子振动均在安全范围内。实验结果表明，基于喘振检测与通过转子轴向悬浮位置调整叶尖间隙的喘振控制方法可以提升磁悬浮鼓风机的稳定运行范围。