Application of active magnetic bearings in flexible rotordynamic systems - A state-of-the-art review

H∞ control of active magnetic suspension

A new in-line mode coupling interferometer based on photonic crystal fiber (PCF) was designed for hydrogen sensing. The external surface of the PCF was coated with Pd-WO3 hydrogen-sensitive film using the sol–gel scheme. Pd-WO3 film refractive index and volume changing influenced the model of the PCF interferometer while the hydrogen concentration was changing, which caused the output spectrum to shift. Therefore, the relationship between the wavelength shift and the hydrogen concentration was established. In the experiment, the wavelength shift showed good linearity as the hydrogen concentration changed from 0% to 1%, while the sensitivity was 1.09 nm/% and the detection resolution was 0.3 perthousand. The sensor showed good repeatability and the wavelength error was less than 40 pm in 30 min. In addition, the sensor was not affected by external temperature fluctuations, which indicates good practical development prospects.

High-Sensitive Hydrogen Sensor Based on Photonic Crystal Fiber Model Interferometer

Research and applications of active bearings: A state-of-the-art review

Adaptive back stepping control (ABC) is originally applied to a linearized model of an active magnetic bearing (AMB) system. Our control goal is to regulate the deviation of the magnetic bearing from its equilibrium position in the presence of an external disturbance and system uncertainties. Two types of ABC methods are developed on the AMB system. One is based on full state feedback, for which displacement, velocity, and current states are assumed available. The other one is adaptive observer based back stepping controller (AOBC) where only displacement output is measurable. An observer is designed for AOBC to estimate velocity and current states of AMB. Lyapunov approach proves the stabilities of both regular ABC and AOBC. Simulation results demonstrate the effectiveness and robustness of two controllers.

https://engagedscholarship.csuohio.edu/cgi/viewcontent.cgi?article=1330&context=enece_facpub

Adaptive Control of an Active Magnetic Bearing With External Disturbance

In this work the modeling and basic control design process of a rotary flexible spindle hovered by Active Magnetic Bearings (AMB) whose good capabilities for machine-tool industry extensively treated in the literature is presented. The modeling takes into account the three main behavioral characteristics of such magnetically-levitated rotor: the rigid dynamics, the flexible dynamics and the rotating unbalanced motion. Besides, the gyroscopic coupling is also studied proving that in this case, its effects are not significant and can be neglected. Using this model, a stabilizing controller based on symmetry properties is successfully designed for the system and a complete experimental analysis of its performance is carried out. Also, the predictions of the model are compared with the actual measured experimental results on a laboratory set-up based on the MBC500 Rotor Dynamics. Afterwards, a brief study about some nonlinear behavior observed in the system and its effect over the system stability at the critical speed is included.

Modeling and control of a flexible rotor system with AMB-based sustentation

2-DOF Controller Design for Precise Positioning a Spindle Levitated with Active Magnetic Bearings

The methodology for the nonlinear modelling and analysis of active magnetic bearing (AMB) systems in the harmonic domain (HD) is presented. This approach is based on the HD linearisation of the AMB system around nonlinear stationary solutions at different rotating speeds. The main advantage obtained is the representation of the periodic LTV models that describe the steady-state dynamics for each speed, by means of LTI models in the HD. In order to show its possibilities, the proposed approach is applied to an AMB laboratory testbed based on the MBC500 Rotor Dynamics from Launchpoint Technologies. This analysis explains the nonlinear nature of the response that appears at high speeds, due to the large oscillations introduced by the shaft unbalance, and detects a low-frequency gain loss when increasing the rotating speed. This phenomenon causes the instability of the system, leading to destructive crashes. In addition, the analysis allows to take into account the effect of the delay introduced by the calculation time in the system behaviour when the controller is implemented by using digital devices.

Nonlinear modelling and analysis of active magnetic bearing systems in the harmonic domain: a case study

This paper describes a stability analysis and a Hinfin robust control design for an electromechanical system consisting of a rotary flexible spindle hovered by active magnetic bearings (AMB), whose potential uses in the machine-tool industry have been well documented. Firstly, a complete experimental stability analysis is performed controlled by a previously designed PID controller. This is performed via the ISO 14839-3 standard, which reliability needs to probe the negligibility of some effects. Then, since the lack of robustness is concluded by the previous study, an Hinfin control design is accomplished. Moreover, the ill-conditioning of the matrices when the DGKF algorithms are solved, is avoided performing a model reduction. This is carried out by means of the symmetry properties which characterize the system and hence, facilitating the design. The better behavior of the system is probed by simulation in a complete model of the real device.

Stability analysis and robust control design on an AMB system

Large scientific projects present new technological challenges, such as the distributed control over a communication network. In particular, the middleware Experimental Physics and Industrial Control System (EPICS) is the most extended communication standard in particle accelerators. The integration of modern control architectures in these EPICS networks is becoming common, as for example for the PXI/PXIe and xTCA hardware alternatives. In this paper, a different integration procedure for PXI/PXIe real-time controllers from National Instruments is proposed, using LabVIEW as the design tool. This methodology is considered and its performance is analyzed by means of a set of laboratory experiments. This control architecture is proposed for achieving the implementation requirements of fast controllers, which need an important amount of computational power and signal processing capability, with a tight real-time demand. The present paper studies the advantages and drawbacks of this methodology and presents its comprehensive evaluation by means of a laboratory test bench, designed for the application of systematic tests. These tests compare the proposed fast controller performance with a similar system implemented using an standard EPICS IOC provided by the CODAC system.

I. Arredondo

Papers

Modeling and control of a flexible rotor system with AMB-based sustentation

2-DOF Controller Design for Precise Positioning a Spindle Levitated with Active Magnetic Bearings

Nonlinear modelling and analysis of active magnetic bearing systems in the harmonic domain: a case study

Stability analysis and robust control design on an AMB system

Design and Performance Analysis of a Nonstandard EPICS Fast Controller