scholarly journals Design of Active Magnetic Bearing Controllers for Rotors Subjected to Gas Seal Forces

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Jonas S. Lauridsen ◽  
Ilmar F. Santos
Keyword(s):  
High Performance ◽  
Dynamic Test ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Test Facility ◽  
Model Based ◽  
Annular Seal ◽  
Significant Performance ◽  
Dynamic Seal ◽  
Rotor Dynamic

Proper design of feedback controllers is crucial for ensuring high performance of active magnetic bearing (AMB) supported rotor dynamic systems. Annular seals in those systems can contribute significant forces, which, in many cases, are hard to model in advance due to complex geometries of the seal and multiphase fluids. Hence, it can be challenging to design AMB controllers that will guarantee robust performance for these kinds of systems. This paper demonstrates the design, simulation, and experimental results of model-based controllers for AMB systems, subjected to dynamic seal forces. The controllers are found using H∞ and μ synthesis and are based on a global rotor dynamic model in which the seal coefficients are identified in situ. The controllers are implemented in a rotor-dynamic test facility with two radial AMBs and one annular seal with an adjustable inlet pressure. The seal is a smooth annular type, with large clearance (worn seal) and with high preswirl, which generates significant cross-coupled forces. The H∞ controller is designed to compensate for the seal forces and the μ controller is furthermore designed to be robust against a range of pressures across the seal. In this study, the rotor is nonrotating. Experimental and simulation results show that significant performance can be achieved using the model-based controllers compared to a reference decentralized proportional-integral-derivative (PID) controller and robustness against large variations of pressure across the seal can be improved by the use of robust synthesized controllers.

Dynamic Analysis for the Rotor Drop Process and Its Application to a Vertically Levitated Rotor/Active Magnetic Bearing System

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Yulan Zhao ◽  
Guojun Yang ◽  
Patrick Keogh ◽  
Lei Zhao
Keyword(s):  
High Speed ◽  
Sliding Friction ◽  
Engineering Application ◽  
Magnetic Bearing ◽  
Contact Forces ◽  
Active Magnetic Bearing ◽  
Detailed Model ◽  
Vertical Rotor ◽  
Auxiliary Bearing ◽  
Rotor Dynamic

Active magnetic bearings (AMBs) have been utilized widely to support high-speed rotors. However, in the case of AMB failure, emergencies, or overload conditions, the auxiliary bearing is chosen as the backup protector to provide mechanical supports and displacement constraints for the rotor. With lack of support, the auxiliary bearing will catch the dropping rotor. Accordingly, high contact forces and corresponding thermal generation due to mechanical rub are applied on the dynamic contact area. Rapid deterioration may be brought about by excessive dynamic and thermal shocks. Therefore, the auxiliary bearing must be sufficiently robust to guarantee the safety of the AMB system. Many approaches have been put forward in the literature to estimate the rotor dynamic motion, nonetheless most of them focus on the horizontal rotor drop and few consider the inclination around the horizontal plane for the vertical rotor. The main purpose of this paper is to predict the rotor dynamic behavior accurately for the vertical rotor drop case. A detailed model for the vertical rotor drop process with consideration of the rotating inclination around x- and y-axes is proposed in this paper. Additionally, rolling and sliding friction are distinguished in the simulation scenario. This model has been applied to estimate the rotor drop process in a helium circulator system equipped with AMBs for the 10 MW high-temperature gas-cooled reactor (HTR-10). The HTR-10 has been designed and researched by the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University. The auxiliary bearing is utilized to support the rotor in the helium circulator. The validity of this model is verified by the results obtained in this paper as well. This paper also provides suggestions for the further improvement of auxiliary bearing design and engineering application.

A Contribution on the Investigation of the Dynamic Behaviour of Rotating Shafts With a Hybrid Magnetic Bearing Concept (HMBC) for Blower Application

2008 ◽  
Author(s):  
Martin Gronek ◽  
Torsten Rottenbach ◽  
Frank Worlitz
Keyword(s):  
Energy Supply ◽  
High Speed ◽  
Experimental Tests ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Analytical Models ◽  
Test Facility ◽  
Reactor Technology ◽  
Rotating Shafts ◽  
Technical Features

Within a subproject of the RAPHAEL-Program, which is part of the 6th EURATOM Framework Program supervised by the European Commission it was investigated whether the use of a Hybrid Magnetic Bearing Concept (HMBC) will be beneficial for a blower application. As in the RAPHAEL program the subproject “Component Development” deals with R&D on components of High Temperature Reactor Technology (HTR), a major focus is on safety- and reliability-related issues. That implies special requirements for the support of high speed rotating shafts in HTR-Applications that only can be satisfied by using Active Magnetic Bearings (AMB). Regarding safety and competitiveness, AMBs are considered key components for the support of rotating HTR-components due to their technical features. AMBs are characterized by an electromagnetic actuator that is generating the bearing force depending on the clearance between stator and rotor, in which the rotor is levitated. Therefore an active control of the coil current is necessary. Furthermore, Touch Down Bearings (TDB) are needed to avoid damages in case of an emergency shut down or in case of energy supply losses. This contribution provides an internal insight on the advantages of a Hybrid Magnetic Bearing Concept that is characterized by a completely Active Magnetic Bearing-supported vertical arranged rotor and an additional permanent magnetic Radial Bearing. One benefit of the HMBC is an additional radial guidance of the shaft that may reduce the loads while dropping into the Touch Down Bearings e.g. in case of energy supply losses of the AMBs. Reduced loads on the TDBs will increase their life cycle and the availability of the AMB supported component. The Scope of this R&D-Project, which will be described more detailed in this contribution, includes the analytical modeling and simulation of the dynamic behavior of the Hybrid Magnetic Bearing System, the modification of the completely AMB-supported test facility FLP500 with a radial PMB and the experimental tests and validation of the analytical models to provide recommendations for the investigated blower application as an HTR-component. Furthermore, the effects occurring during the modification of the test facility and the approach that was necessary to solve unexpected problems will be described.

Dynamic responses of the rotor supported by a new type zero-clearance catcher bearing

2017 ◽  
Vol 31 (19-21) ◽  
pp. 1740014
Author(s):  
Yi-Li Zhu ◽  
Zhong-Qiao Zheng
Keyword(s):  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Dynamic Responses ◽  
Failure Event ◽  
Long Time ◽  
New Type ◽  
Amb System ◽  
Rotor Dynamic

Catcher bearings (CB) are required to support the rotor rotating for some time when a failure event of active magnetic bearing (AMB) system occurs. For this purpose, a new type zero-clearance catcher bearing (NTZCB) is proposed. The influences of different parameters of NTZCB on the rotor dynamic responses are theoretically and experimentally analyzed. The results indicate that choosing relatively soft spring and heavy moveable supporting pedestal can effectively buffer the rotor vibrations, which makes it possible for the rotor to keep rotating with the support of the CB system for a long time.

Design of model-based unbalance compensator with fuzzy gain tuning mechanism for an active magnetic bearing system

2011 ◽  
Vol 38 (10) ◽  
pp. 12861-12868 ◽  
Author(s):  
Pi-Cheng Tung ◽  
Mong-Tao Tsai ◽  
Kuan-Yu Chen ◽  
Yi-Hua Fan ◽  
Fu-Chu Chou
Keyword(s):  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Tuning Mechanism ◽  
Model Based ◽  
Bearing System

Residual Unbalanced Mass Determination of an AMBs Controlled Rotor Based on Control Current Analysis of the Feedback Loop

2018 ◽  
Author(s):  
Tianpeng Fan ◽  
Zhe Sun ◽  
Xiaoshen Zhang ◽  
Xunshi Yan ◽  
Jingjing Zhao ◽  
...  
Keyword(s):  
High Speed ◽  
High Performance ◽  
Feedback Loop ◽  
Image Data ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Current Analysis ◽  
Unbalanced Mass ◽  
Control Current

Active magnetic bearing technology is used more and more for its high performance, such as high speed and frictionless operation. But the rotor vibrates sometimes during operation due to the existence of residual unbalanced mass, which may affect the security of the whole system. In order to determine the distribution of residual unbalanced mass, this paper proposes a method based on frequency response, control current analysis, and image data processing. The theoretical and calculated results show the validity of the method.

Track-Following Controller Design Using an Active Magnetic Bearing for Measurement of the Rotor Dynamics Coefficient of the Annular Seal

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Shota Yabui ◽  
Hideyuki Inoue ◽  
Tsuyoshi Inoue
Keyword(s):  
Control System ◽  
Controller Design ◽  
Rotor Dynamics ◽  
Magnetic Bearing ◽  
Operating Conditions ◽  
Active Magnetic Bearing ◽  
Rotating Shaft ◽  
Operating Condition ◽  
Rotating Machine ◽  
Annular Seal

Abstract This study introduces a track-following controller design to measure the rotor dynamics (RD) coefficient of the annular seal using active magnetic bearings. The annular seal is implemented contiguously to prevent leakage of fluid between the rotating shaft and stationary area of a rotating machine. The force caused by the seal at the contact point can cause vibrations, which should be identified for designing rotating machinery. The RD force is coupled with mechanical and fluid dynamics. Moreover, the dynamics depend on the operating conditions of the rotating machine, namely, the rotating speed and orbit of the rotating shaft. This study proposes a control system for the active magnetic bearing to measure the RD force directly at the arbitrary operating condition. The main controller is designed to satisfy a criterion of the frequency characteristics of the rotating system. In addition, the control system employs adaptive feed-forward cancellation (AFC). This can estimate and compensate for the RD force in the control system simultaneously. The experimental results indicate that the control system can achieve an arbitrary operating condition and measure the RD coefficient of the annular seal in real-time. As a result, the RD coefficient is identified based on the equation of motion.

scholarly journals On-Site Identification of Dynamic Annular Seal Forces in Turbo Machinery Using Active Magnetic Bearings: An Experimental Investigation

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Jonas S. Lauridsen ◽  
Ilmar F. Santos
Keyword(s):  
A Priori ◽  
Global Model ◽  
Magnetic Bearings ◽  
Test Facility ◽  
System Response ◽  
Active Magnetic Bearings ◽  
Machine Failure ◽  
Annular Seal ◽  
Dynamic Seal ◽  
Site Identification

Significant dynamic forces can be generated by annular seals in rotordynamics and can under certain conditions destabilize the system leading to a machine failure. Mathematical modeling of dynamic seal forces are still challenging, especially for multiphase fluids and for seals with complex geometries. This results in much uncertainty in the estimation of the dynamic seal forces, which often leads to unexpected system behavior. This paper presents the results of a method suitable for on-site identification of uncertain dynamic annular seal forces in rotordynamic systems supported by active magnetic bearings (AMB). An excitation current is applied through the AMBs to obtain perturbation forces and a system response, from which the seal coefficients are extracted by utilizing optimization and a priori information about the mathematical model structure and its known system dynamics. As a study case, the method is applied to a full-scale test facility supported by two radial AMBs interacting with one annular center-mounted test seal. Specifically, the dynamic behavior of a smooth annular seal with high preswirl and large clearance (worn seal) is investigated in this study for different excitation frequencies and differential pressures across the seal. The seal coefficients are extracted and a global model on reduced state-space modal form is obtained using the identification process. The global model can be used to update the model-based controller to improve the performance of the overall system. This could potentially be implemented in all rotordynamic systems supported by AMBs and subjected to seal forces or other fluid film forces.

Test Results and Analytical Predictions for Rotor Drop Testing of an Active Magnetic Bearing Expander/Generator

2006 ◽  
Vol 129 (2) ◽  
pp. 522-529 ◽  
Author(s):  
Lawrence Hawkins ◽  
Alexei Filatov ◽  
Shamim Imani ◽  
Darren Prosser
Keyword(s):  
High Speed ◽  
High Performance ◽  
Time History ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Test Results ◽  
Direct Drive ◽  
Flow Loop ◽  
Low Loss ◽  
Full Speed

A cryogenic gas expander system that incorporates a high-performance, high-speed permanent magnet, direct-drive generator and low loss magnetic bearings is described. Flow loop testing to 30,000rpm was completed at the system manufacturer’s facility in January 2005, and field installation is scheduled for October 2005. As part of the system testing, the rotor was dropped onto the backup bearings multiple times at an intermediate speed and at 30,000rpm. Orbit and time-history data from a full speed drop and spin down are presented and discussed in detail. A transient, nonlinear rotordynamic analysis simulation model was developed for the machine to provide insight into the dynamic behavior. The model includes the dead band clearance, the flexible backup bearing support, and hard stop. Model predictions are discussed relative to the test data.

scholarly journals Design and Calibration of a Full Scale Active Magnetic Bearing Based Test Facility for Investigating Rotordynamic Properties of Turbomachinery Seals in Multiphase Flow

2016 ◽  
Author(s):  
Andreas Jauernik Voigt ◽  
Christian Mandrup-Poulsen ◽  
Kenny Krogh Nielsen ◽  
Ilmar F. Santos
Keyword(s):  
Multiphase Flow ◽  
Oil And Gas ◽  
Magnetic Bearing ◽  
Gas Production ◽  
Hall Sensor ◽  
Full Scale ◽  
Active Magnetic Bearing ◽  
Sensor System ◽  
Test Facility ◽  
Process Equipment

The recent move towards subsea oil and gas production brings about a requirement to locate process equipment in deepwater installations. Furthermore, there is a drive towards omitting well stream separation functionality, as this adds complexity and cost to the subsea installation. This in turn leads to technical challenges for the subsea installed pumps and compressors that are now required to handle multiphase flow of varying gas to liquid ratios. This highlights the necessity for a strong research focus on multiphase flow impact on rotordynamic properties and thereby operational stability of the subsea installed rotating machinery. It is well known that careful design of turbomachinery seals, such as interstage and balance piston seals, is pivotal for the performance of pumps and compressors. Consequently, the ability to predict the complex interaction between fluid dynamics and rotordynamics within these seals is key. Numerical tools offering predictive capabilities for turbomachinery seals in multiphase flow are currently being developed and refined, however the lack of experimental data for multiphase seals renders benchmarking and validation impossible. To this end, the Technical University of Denmark and Lloyd’s Register Consulting are currently establishing a purpose built state of the art multiphase seal test facility, which is divided into three modules. Module I consists of a full scale Active Magnetic Bearing (AMB) based rotordynamic test bench. The internally designed custom AMBs are equipped with an embedded Hall sensor system enabling high-precision non-contact seal force quantification. Module II is a fully automatised calibration facility for the Hall sensor based force quantification system. Module III consists of the test seal housing assembly. This paper provides details on the design of the novel test facility and the calibration of the Hall sensor system employed to measure AMB forces. Calibration and validation results are presented, along with an uncertainty analysis on the force quantification capabilities.

Rotordynamic Behavior of Leaf Seals: Measurement of Frequency-Dependent Force Coefficients for Varying Inlet Parameters

2020 ◽  
Author(s):  
Clemens Griebel
Keyword(s):  
Dynamic Test ◽  
Operating Parameter ◽  
Labyrinth Seal ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Impedance Method ◽  
Force Coefficients ◽  
Leaf Pack ◽  
Dynamics Simulations ◽  
Positive Direct

Abstract While brush seals can be found in various applications for turbomachines today, leaf seals are a further development in compliant seal technology and have a lower level of maturity. Among the purported advantages are greater axial rigidity when subject to higher pressure differences and the potential for non-contacting operation due to lift-up. However, especially their rotordynamic behavior is little investigated in the literature so far. In this paper, measured rotordynamic force coefficients of a leaf seal are presented for varying inlet pressures, preswirl velocities and excitation frequencies. The leaf pack of the tested leaf seal has zero rotor cold clearance and its coverplates are designed for facilitating a lift-up effect when pressurizing the seal. Experiments were performed on a dynamic test rig with whirling rotor using active magnetic bearing technology and evaluated in the frequency domain based on the impedance method. Test results for the leaf seal reveal positive direct stiffness and an advantageous rotordynamic behavior due to significant levels of direct damping and negative cross-coupled stiffness throughout the operating parameter range. Leaf seal results are compared to brush and labyrinth seal data from previous studies for varying inlet pressures and preswirl velocities. Additional computational fluid dynamics simulations were carried out to predict the leaf deflection moment, which support the findings regarding hydrostatic lift-up from the experimental results.

Sign in / Sign up

Export Citation Format

Share Document