Design, Construction, and Modeling of a Flexible Rotor Active Magnetic Bearing Test Rig

Mushi, S.; Lin, Zongli; Allaire, Paul E.

doi:10.1109/tmech.2011.2160456

Cited by 120 publications

(52 citation statements)

References 17 publications

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“…Therefore, the control of the AMB system has been an active research topic. For example, [4] presented a feedback linearization approach to control the position of a horizontal rotor; [5], aiming at a 1-kWh flywheel energy storage device, analyzed the advantages and disadvantages of different approaches, such as decentralized control, Linear Quadratic Regulator (LQR) control and cross-feedback control; [6] proposed an on-line parameter identification method to solve the situation in which the rotor mass is unbalanced; [7], based on an AMB test rig, used radial basis function networks to identify the uncertainties and to synthesize an H ∞ controller with the rotor setpoint; [8] presented an adaptive back-stepped controller for a flywheel energy storage system; [9] designed a test rig consisting of a flexible rotor supported by AMBs with a µ−synthesis controller.…”

Section: Introductionmentioning

confidence: 99%

L1 Adaptive Control for a Vertical Rotor Orientation System

Liu

Yang

et al. 2016

Applied Sciences

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Bottom-fixed vertical rotating devices are widely used in industrial and civilian fields. The free upside of the rotor will cause vibration and lead to noise and damage during operation. Meanwhile, parameter uncertainties, nonlinearities and external disturbances will further deteriorate the performance of the rotor. Therefore, in this paper, we present a rotor orientation control system based on an active magnetic bearing with L 1 adaptive control to restrain the influence of the nonlinearity and uncertainty and reduce the vibration amplitude of the vertical rotor. The boundedness and stability of the adaptive system are analyzed via a theoretical derivation. The impact of the adaptive gain is discussed through simulation. An experimental rig based on dSPACE is designed to test the validity of the rotor orientation system. The experimental results show that the relative vibration amplitude of the rotor using the L 1 adaptive controller will be reduced to ∼50% of that in the initial state, which is a 10% greater reduction than can be achieved with the nonadaptive controller. The control approach in this paper is of some significance to solve the orientation control problem in a low-speed vertical rotor with uncertainties and nonlinearities.

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Section: Introductionmentioning

confidence: 99%

L1 Adaptive Control for a Vertical Rotor Orientation System

Liu

Yang

et al. 2016

Applied Sciences

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“…Modeling seals using computational fluid dynamics (CFD) is capable of capturing more details on the fluid-structure interactions and are an improvement over the bulk flow models. However, significant uncertainty is still documented in predictions of dynamic seal coefficients highlighting the need for experiments to improve our knowledge of the underlying physics (Kocur et al, 2007;Wagner et al, 2009 1) where MW is the gas molecular weight, D is impeller diameter (m), h is the restrictive dimension in the flow path (m), f is the rotation speed (Hz), P is compressor mechanical power (kW), ρ D and ρ S are the compressor discharge and suction densities (kg/m 3 ), respectively. Within the last decade, the industry has accepted a modified Alford's equation which replaces the MW with a constant of 30 to better match the database of experience built up from the installed base of centrifugal compressors (API 684, 2005).…”

Section: Rotordynamic Instabilitymentioning

confidence: 99%

“…In Figure 3.7a the control law stabilizes the unstable rigid body modes 1 The definition holds true only if N(s) and D(s) are coprime. For an extension to MIMO systems, we introduce the rational transfer function matrix G(s).…”

Section: Rotor-amb System Descriptionmentioning

confidence: 99%

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Robust Control of Rotordynamic Instability in Rotating Machinery Supported by Active Magnetic Bearings

Mushi

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This dissertation addresses the control challenges for a practical mechatronic system subject to self-excited instability modeled as a parametric uncertainty. Achieving a balance between the conflicting requirements of performance and robustness in the face of system uncertainty is the primary objective of feedback control. Practical issues such as unstable open-loop plant dynamics, finite actuator capacity, the presence structural flexibility and suboptimal sensor/actuator placement limit the achievable performance through the use of feedback.The ROMAC Magnetic Bearing Test Rig for Rotordynamic Instability (MBTRI) is a state-of-the-art experiment designed to investigate algorithms that may affect the region of stability of a rotor-bearing system with respect to rotordynamic instability as a result of aerodynamic cross-coupled stiffness. The onset of rotordynamic instability is a significant challenge to successful design and operation of high speed rotating machinery particularly gas compressors. The unique design of the test rig includes several features of an industrial centrifugal gas compressor with a flexible rotor designed to operate above its first bending critical speed. The impellers and gas seals within compressors are the primary source of load-dependent aerodynamic cross-coupled stiffness forces which can lead to self-excited instability and serious machine damage in the absence of sufficient support damping. During the design phase of rotating machines the accurate prediction of the onset of instability is made difficult by reliance on semi-empirical dynamic models with significant uncertainty. Literature on the rotordynamic instability mechanism reveals that in the presence of optimum support damping, a maximum achievable stability threshold can be derived as a function of physical parameters of the rotor-bearing system. This presents an ideal opportunity for the exploration of optimal robust active vibration control algorithms using active ii magnetic bearings (AMBs). A notable advantage of AMBs is their ability to generate optimal support stiffness and damping characteristics. Unlike passive mechanical bearings, the support characteristics of AMBs may be modified over the operating life of the system without any major hardware changes.A general framework is presented whereby properties of the rotor-AMB system that impose fundamental limitations on achievable performance of the closed-loop system are evaluated as a nominal model of the MBTRI plant dynamic is constructed. This model was validated using system identification techniques, and augmented with uncertainty models representing the effects of variation in parameters such operating speed and the magnitude of the destabilizing stiffness. Using µ-synthesis several robust controllers were designed and implemented on the MBTRI hardware to investigate their effect on the stability threshold. The best controller established a thirty-six percent increase in the stability threshold over an existing benchmark controller. This represented an ...

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“…However, none of these fluid-based bearings offer any means of real-time bearing and rotordynamic control. Magnetic bearings are utilized in select applications as well, providing the benefits of both greater efficiency and rotordynamic control [20][21][22][23][24][25][26][27][28][29], though their use often comes at the expense of high energy consumption, limited load capacity, higher cost, and the requirement for backup bearing systems for energy-loss or control-loss emergency scenarios. Electro-rheological and magneto-rheological fluids have also been proposed as "smart" fluids that could be used to increase bearing performance, though these are still in the early stages of development due to extreme technological demands [30,31].…”

Section: Unnecessary Shearmentioning

confidence: 99%

Gas-Expanded Lubricants for Increased Energy Efficiency and Control in Rotating Machinery

Weaver¹

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Design, Construction, and Modeling of a Flexible Rotor Active Magnetic Bearing Test Rig

Cited by 120 publications

References 17 publications

L1 Adaptive Control for a Vertical Rotor Orientation System

L1 Adaptive Control for a Vertical Rotor Orientation System

Robust Control of Rotordynamic Instability in Rotating Machinery Supported by Active Magnetic Bearings

Gas-Expanded Lubricants for Increased Energy Efficiency and Control in Rotating Machinery

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