scholarly journals Performances Comparison for a Rotating Shaft Suspended by 4-Axis Radial Active Magnetic Bearings via -Synthesis, Loop-Shaping Design, and Subwith Uncertainties

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
G. Barbaraci ◽  
G. Virzi' Mariotti
Keyword(s):  
Pid Controller ◽  
Angular Speed ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Operating Point ◽  
Rotating Shaft ◽  
Simple Rules ◽  
Lqr Controller ◽  
Point Condition ◽  
Multiple Controller

The control systems applied on active magnetic bearing are several. A perfect levitation is characterized by maintaining the operating point condition that is characterized by the center of stator coincident with the geometric center of shaft. The first controller implemented for this purpose is PID controller that is characterized by an algorithm that leads the amplifier to produce control current until the operating point condition is not reached, this is obtained by an integration operator. The effect of an integrator is essential but not necessary for a centered levitation for example in the robust control characterized by a dynamic model depended on plant of system so that it depends on angular speed as LQR controller does. In LQR there is not integrator so there is not a perfectly centered section of shaft with center of stator. On contrary PID controller does not depend on angular speed and it can be easily implemented according some simple rules. Predictive control is another interesting controller characterized by a multiple controller operating in different condition in order to get the minimum of cost function, but also in this case the angular speed is introduce for the same reason discussed before.

Dynamic Analysis of Flexible Rotor Suspended by Active Magnetic Bearings With LQR Controller

2018 ◽  
Author(s):  
Yixin Su ◽  
Yanhui Ma ◽  
Qian Shi ◽  
Suyuan Yu
Keyword(s):  
Dynamic Characteristics ◽  
Beam Theory ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Flexible Rotor ◽  
Linear Quadratic ◽  
State Response ◽  
Lagrange’S Equation ◽  
Linear Quadratic Regulation ◽  
Lqr Controller

Dynamic characteristics of active magnetic bearing (AMB)-flexible rotor system are closely related to control law. To analyze dynamic characteristics of flexible rotor suspended by AMBs with linear quadratic regulation (LQR) controller, a simple and effective method based on numerical calculation of unbalanced response is proposed in this article. The model of flexible rotor is established based upon Euler-Bernoulli beam theory and Lagrange’s equation. Disc on the rotor and its Gyro effect are taken into account. LQR controller based on error and its derivative is developed to control electromagnetic force of AMB at each degree of freedom (DOF) in real time. Under the unbalanced exciting force, the steady-state response and transient response in time domain of each node of flexible rotor at 0–4000 rad/s are calculated numerically. The critical speeds of rotor are obtained by identification method quickly and easily.

scholarly journals Exploration of NDE Properties of AMB Supported Rotors for Structural Damage Detection

2010 ◽  
Author(s):  
Jerzy T. Sawicki ◽  
Dmitry L. Storozhev ◽  
John D. Lekki
Keyword(s):  
Structural Damage ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Line Detection ◽  
Control Loop ◽  
Structural Damage Detection ◽  
Cracked Rotor ◽  
Rotating Shaft ◽  
On Line ◽  
Combination Frequencies

This paper addresses self-diagnostic properties of AMB (active magnetic bearing) supported rotors for on-line detection of the transverse crack on a rotating shaft. In addition to pure levitation, the rotor supporting bearing also serves as an actuator that transforms current signals additionally injected into the control loop into the superimposed specially selected excitation forces into the suspended rotor. These additional excitations induce combination frequencies in the rotor response, providing unique signatures for the presence of crack. The background of theoretical modeling, experimental and computer simulation results for the AMB supported cracked rotor with self-diagnostic excitation forces are presented and discussed.

Influence of Retainer Bearing Misalignment on the Performance of Active Magnetic Bearing

2012 ◽  
Vol 588-589 ◽  
pp. 141-146 ◽  
Author(s):  
Hong Wei Li ◽  
Wen Tao Yu ◽  
You Peng Fan ◽  
Shu Qin Liu
Keyword(s):  
Pid Controller ◽  
Damping Ratio ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
System Structure ◽  
Design System ◽  
Force Model ◽  
Low Pass ◽  
And Performance ◽  
Low Pass Filters

The retainer bearing will be misaligned for mechanical errors, which leads to the uneven air gap of AMB and affects the performance of AMB. To study this problem, the electric-magnetic force model was built first with the misalignment of retainer bearing. With this model, the influences of the misalignment on the system stiffness, damping and damping ratio of AMB were studied through theory analysis and simulation based on the PID controller with low-pass filters. The study indicates that the system stiffness and damping ratio of AMB employing PID controller will increase with the increase of retainer bearing misalignment. The results provide certain references for the system structure optimum design, system debugging and fault diagnosis and performance improvement of AMB-rotor system.

The Robust Control of Magnetic Suspension with Rapidly Changing of Rotor Speed

2009 ◽  
Vol 147-149 ◽  
pp. 302-307 ◽  
Author(s):  
Arkadiusz Mystkowski ◽  
Zdzisław Gosiewski
Keyword(s):  
Control System ◽  
Robust Control ◽  
High Speed ◽  
Controller Design ◽  
Angular Speed ◽  
Magnetic Bearing ◽  
Magnetic Suspension ◽  
Experimental Results ◽  
Active Magnetic Bearing ◽  
Robust Controller

An optimal robust vibration control of a rotor supported magnetically over a wide angular speed range is presented in the paper. The laboratory stand with the high speed rotor (max. 24000 rpm) was designed. The wide bandwidth controller with required gain, which is necessary to stabilize the structurally unstable and active magnetic bearing system was computed. For controller design, the weighting functions putted on the input and output signals were chosen. For control design, the dynamics of the rotor and uncertain parameters were considered. The optimized control system by minimization of the H norm putted on transient process of the system was presented. The robust controller was designed with considered asymmetrically magnetic bearings, signal limits and power amplifiers dynamic. The success of the robust control is demonstrated through computer simulations and experimental results. Matlab-Simulink was used for the numerical simulation. The experimental results show the effectiveness of the control system as good vibrations reducing and robustness of the designed controller in all dynamic states.

scholarly journals Vibration Reduction of an Overhung Rotor Supported by an Active Magnetic Bearing Using a Decoupling Control System

Machines ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 73
Author(s):  
Nitisak Numanoy ◽  
Jiraphon Srisertpol
Keyword(s):  
Pid Controller ◽  
Lateral Force ◽  
Harmonic Excitation ◽  
Magnetic Bearing ◽  
Decoupling Control ◽  
Active Magnetic Bearing ◽  
Central Position ◽  
Operational Conditions ◽  
Run Up ◽  
Overhung Rotors

Overhung rotors are important for use in industrial turbo-machines. The effects of a lateral force can increase as a result of the rotor weight, misalignment, or the operating speed of the suspension system for which the rotor is carrying a transmission connection. In this paper, the reduction of vibration in supported lateral directions by varying control is discussed in a radial active magnetic bearing system (AMBS). An experimental test was conducted on the orbital response of an overhung rotor supported by an AMBS, to provide an alternative for improving precision. To simplify the system design, decoupling was achieved using a PID controller and harmonic disturbance compensator (HDC), which improved the rotating performance of an overhung active magnetic bearing (AMB) rotor system, using a frequency response function (FRF) approach and a description of the overhung rotor during normal operational conditions at unique frequencies. The experimental results show that the precision rotation, due to harmonic excitation of the shaft orbit, can be removed in real time using compensation signals using trigonometry. The compensation criteria for the changed run-up and coast-down consistently helped to maintain the rotational center in a central position. A reduction of up to 55% in vibration amplitude on average was achieved under appropriate conditions, and the significance of the overhung rotor symptoms faults were investigated.

Development of Experimental Active Magnetic Bearing Device for Measurement of Mechanical Seal Reaction Force Acting on Rotor

2018 ◽  
Author(s):  
Hiroki Manabe ◽  
Shota Yabui ◽  
Hideyuki Inoue ◽  
Tsuyoshi Inoue
Keyword(s):  
Force Measurement ◽  
Reaction Force ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Mechanical Seal ◽  
Rotating Shaft ◽  
Fluid Force ◽  
Fluid Forces ◽  
Whirling Motion ◽  
Measurement And Evaluation

In turbomachinery, seals are used to prevent fluid leakage. At seal part, rotordynamic fluid force (RD fluid force), which causes whirling motion of rotor, is generated. Under certain conditions, the RD fluid force may contribute to instability of the machine. There are several cases that the whirling is accompanied by eccentricity due to the influence of gravity, or the whirling orbit becomes elliptical due to the influence of the bearing support anisotropy. In these cases, mathematical modeling of the RD fluid forces becomes increasingly complex. As a result, the RD fluid force measurement is more preferable. To improve the measurement and evaluation technology of the RD fluid force, a method to arbitrarily control whirling of the orbit is required. In this paper, RD fluid force measurement by controlling the shape of the orbit using an active magnetic bearing (AMB) is proposed. A contact type mechanical seal is used as a test specimen. When the rotating shaft is whirling, the RD fluid force due to hydrodynamics lubrication and the frictional force due to contact occur on the sliding surface. The resultant force of these forces is taken as the reaction force of mechanical seal and the measurement is performed. The measured reaction force of the mechanical seal is compared with simulation results and the validity of the proposed measurement method is confirmed.

Design of a Highly Integrated Active Magnetic Bearing With Six Coupled Actuators for High Precision Rotation Applications

1999 ◽  
Author(s):  
M. Kümmerle ◽  
B. Aeschlimann ◽  
J. Zoethout ◽  
T. Belfroid ◽  
R. Vuillemin ◽  
...  
Keyword(s):  
High Precision ◽  
Pid Controller ◽  
Degrees Of Freedom ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
The Other ◽  
Axial Forces ◽  
Functional Prototype ◽  
The One ◽  
Contact Free

Abstract This paper presents the design and the implementation of a contact free Active Magnetic Bearing (AMB) for high precision rotation applications. For controlling five Degrees of Freedom (DOF) of the rotor six coupled reluctance force actuators (creating radial and axial forces at the same time) are used. A method for designing the actuators in order to meet the specifications is described. Two different controller schemes using different sensor configurations have been implemented on a functional prototype: On the one hand a conventional decentralized PID controller, on the other hand a more centralized structure.

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.

Improvement of Low Frequency Vibration Isolation Capability of AMB Using a Cascade PID Controller

2018 ◽  
Author(s):  
Yixin Su ◽  
Yanhui Ma ◽  
Yongpeng Gu ◽  
Suyuan Yu ◽  
Gexue Ren
Keyword(s):  
Pid Controller ◽  
Vibration Isolation ◽  
Dynamic Performance ◽  
Low Frequency ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Control Parameters ◽  
Control Loops ◽  
Low Frequency Vibration ◽  
Wide Range

In contrast with traditional mechanical bearing, Active magnetic bearing (AMB) has no friction and lubrication, and its dynamic performance can be adjusted by active control. To isolate low frequency vibration of the rotating machinery under 50Hz, a novel design of cascade PID controller (CPC) with two control loops for AMB is proposed. The main loop is a position loop and the secondary loop is a transmission force loop. According to the theoretical derivations in this study, the CPC controls both the rotor position and the transmission force. Even when the control parameters maintain constant, the dynamic characteristic parameters, equivalent stiffness and equivalent damping, vary with frequency continuously and smoothly. Therefore, they can be adjusted in a wide range to achieve isolation of low frequency vibration when using proper control parameters. A simulation example shows that the transmission force with a CPC is lower in the 8–50Hz when the rotor displacement is almost same as with a single stage PID controller (SSPC). Experimental verification was carried out in an experimental bench of AMB under unbalanced rotor condition. Results show that a CPC can reduce the vibration acceleration at 15–50Hz especially near the peaks. Simulation and experimental results well demonstrate the effectiveness and guaranteed stability of the CPC in the present study.

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