Stability of Rotating Machinery Supported on Active Magnetic Bearings Subjected to Base Excitation

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Clément Jarroux ◽  
Jarir Mahfoud ◽  
Benjamin Defoy ◽  
Thomas Alban
Keyword(s):  
Rotating Machinery ◽  
Magnetic Bearings ◽  
System Stability ◽  
Experimental Investigations ◽  
System Response ◽  
Fe Model ◽  
Active Magnetic Bearings ◽  
Strong Base ◽  
The Stability ◽  
Amb System

Abstract The stability of rotating machinery is a major challenge for the floating production storage and offloading (FPSO) units such as steam turbines or centrifugal compressors. The use of active magnetic bearings (AMBs) in turbomachines enables high operating speeds, active mechatronic system for the diagnostics, and the control and enables downsizing of the whole installation footprint. In case of strong base motions, the rotor can contact its touchdown bearings (TDBs) which are used as emergency and landing bearings. The aim of this study is to assess the stability of a rotating machine supported on AMBs during severe foundation excitation. The combined effect of unbalance forces, base motion excitation, and contact non-linearity on a rotor–AMB system response is analyzed focusing on the capacity of an augmented proportional-integral-derivative controller to maintain the system stable. An academic scale test rig was used for the experimental investigations. The controller was efficient and able to maintain the system stable during and after the application of the excitation, but the dynamic capacity of the AMBs was largely oversized with respect to the studied system. In order to check the capacity of the AMBs, when they are designed as a function of the rotor weight and expected excitation, numerical simulations were carried out (downsized). A finite element (FE) model was developed to model the on-board rotor–AMB system. Predicted and measured responses due to impulse excitation applied on the foundations were compared. The capacity of the controller to maintain the system stability is then discussed.

Stability of Ring-Type MEMS Gyroscopes Subjected to Stochastic Angular Speed Fluctuation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Samuel F. Asokanthan ◽  
Soroush Arghavan ◽  
Mohamed Bognash
Keyword(s):  
Angular Velocity ◽  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Damping Ratio ◽  
Operating Conditions ◽  
System Stability ◽  
System Response ◽  
Ring Type ◽  
Mems Gyroscopes ◽  
The Stability

Effect of stochastic fluctuations in angular velocity on the stability of two degrees-of-freedom ring-type microelectromechanical systems (MEMS) gyroscopes is investigated. The governing stochastic differential equations (SDEs) are discretized using the higher-order Milstein scheme in order to numerically predict the system response assuming the fluctuations to be white noise. Simulations via Euler scheme as well as a measure of largest Lyapunov exponents (LLEs) are employed for validation purposes due to lack of similar analytical or experimental data. The response of the gyroscope under different noise fluctuation magnitudes has been computed to ascertain the stability behavior of the system. External noise that affect the gyroscope dynamic behavior typically results from environment factors and the nature of the system operation can be exerted on the system at any frequency range depending on the source. Hence, a parametric study is performed to assess the noise intensity stability threshold for a number of damping ratio values. The stability investigation predicts the form of threshold fluctuation intensity dependence on damping ratio. Under typical gyroscope operating conditions, nominal input angular velocity magnitude and mass mismatch appear to have minimal influence on system stability.

The μ Approach to Control of Active Magnetic Bearings

2002 ◽  
Vol 124 (3) ◽  
pp. 566-570 ◽  
Author(s):  
R. L. Fittro ◽  
C. R. Knospe
Keyword(s):  
Laboratory Test ◽  
Rotating Machinery ◽  
Vibration Response ◽  
Experimental Results ◽  
Magnetic Bearings ◽  
Pd Controller ◽  
Active Magnetic Bearings ◽  
Test Rig ◽  
Rotor Vibration ◽  
Multivariable Controller

Many important industrial problems in the control of rotating machinery with active magnetic bearings concern the minimization of the rotor vibration response to poorly characterized disturbances at a single or several shaft locations, these typically not corresponding to those of a sensor or actuator. Herein, we examine experimental results of a multivariable controller obtained via μ synthesis with a laboratory test rig. These indicate that a significant improvement in performance can be obtained with a multivariable μ controller over that achieved with an optimal decentralized PD controller.

The μ Approach to Control of Active Magnetic Bearings

2000 ◽  
Author(s):  
Roger L. Fittro ◽  
Carl R. Knospe
Keyword(s):  
Laboratory Test ◽  
Rotating Machinery ◽  
Vibration Response ◽  
Experimental Results ◽  
Magnetic Bearings ◽  
Pd Controller ◽  
Active Magnetic Bearings ◽  
Test Rig ◽  
Rotor Vibration ◽  
Multivariable Controller

Many important industrial problems in the control of rotating machinery with active magnetic bearings concern the minimization of the rotor vibration response to poorly characterized disturbances at a single or several shaft locations, these typically not corresponding to those of a sensor or actuator. Herein, we examine experimental results of a multivariable controller obtained via μ synthesis with a laboratory test rig. These indicate that a significant improvement in performance can be obtained with a multivariable μ controller over that achieved with an optimal decentralized PD controller.

Dynamic Modeling and Analysis of Active Magnetic Bearings

2014 ◽  
Vol 494-495 ◽  
pp. 685-688
Author(s):  
Rong Gao ◽  
Gang Luo ◽  
Cong Xun Yan
Keyword(s):  
Dynamic Characteristic ◽  
Dynamic Modeling ◽  
Magnetic Bearing ◽  
Integrated System ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Modeling And Analysis ◽  
Amb System ◽  
Mathematics Method

Active magnetic bearing (AMB) system is a complex integrated system including mechanics, electronic and magnetism. In order to research for the basic dynamic characteristic of rotor supported by AMB, it is necessary to present mathematics method. The dynamics formula of AMB is established using theory means of dynamics of rotator and mechanics of vibrations. At the same tine, the running stability of rotor is analyzed and the example is presented in detail.

Stability and Response of Rotors Supported on Active Magnetic Bearings

1993 ◽  
Author(s):  
K. Ramesh ◽  
R. G. Kirk
Keyword(s):  
Finite Element ◽  
Stability Analysis ◽  
Transfer Matrix ◽  
Magnetic Bearings ◽  
Active Magnetic Bearings ◽  
Finite Element Program ◽  
Element Program ◽  
Matrix Codes ◽  
The Stability

Abstract A PC-based program has been developed which is capable of performing stability analysis and response calculations of rotor-bearing systems. The paper discusses the modeling of rotors supported on active magnetic bearings (AMB) and highlights the advantages in the modeling using the finite element method, over the transfer matrix method. An 8-stage centrifugal compressor supported on AMB was chosen for the case study. The results for the stability analysis, obtained using the finite element program was compared with those obtained by the well established transfer matrix codes. The results of unbalance response, including the effects of sensor non collocation are presented and this demonstrates how an AMB supported rotor can experience a synchronous instability for selected sensor locations and balance distributions.

Matching Design of Active Magnetic Bearing and Elastic Support Vibration Isolator

2020 ◽  
Author(s):  
Yichen Yao ◽  
Yixin Su ◽  
Tianye Yu ◽  
Gexue Ren ◽  
Suyuan Yu
Keyword(s):  
Frequency Domain ◽  
Vibration Isolation ◽  
Design Method ◽  
Rotating Machinery ◽  
Magnetic Bearings ◽  
Active Magnetic Bearings ◽  
Vibration Isolators ◽  
Active Vibration ◽  
Matching Relation ◽  
Active Vibration Isolation

Abstract In modern industries, high-speed machinery occupies a fundamental place. However, rotating machinery will inevitably produce a variety of structural noise and vibration. Generally, vibration isolation means can be divided into active vibration isolation and passive vibration isolation, among which the most representative are active magnetic bearings (AMBs) and vibration isolators, respectively. The combination of active magnetic bearings and vibration isolators is widely used in rotating machinery because of its excellent effect in vibration and noise reduction. This paper concentrates on the analysis of the vibration transmission mechanism of the active magnetic bearings coupled with the vibration isolators. A 30 kW prototype pump is taken as an example to help describe the research method. The model of the pump is first established. The stationary pump components and the rotor are respectively modeled through the finite element method and converted to substructure modal expression after low-order modal extraction. The bearing force is simplified to spring-dampers with equivalent stiffness and equivalent damping relating to the exciting frequency. The vibration isolators are simplified as three-dimensional spring-dampers. Based on the model, this paper then investigates the matching relation of the AMBs and the vibration isolators and proposes a dynamic vibration isolation design method for the rotor-AMBs-flexible support system. On the basis of the frequency-domain response of the original design, this design method gives the frequency-domain curves of the desired stiffness and damping of the suitable active vibration isolation, which can be used to guide the controller design of the AMBs and isolators selection. According to the design, we have done laboratory experiments on the prototype pump. The results show that the design method based on matching relation has good performance in vibration isolation.

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