scholarly journals Theoretical and Experimental Investigations of Dynamics of the Flexible Rotor with an Additional Active Magnetic Bearing

10.5772/51113 ◽  
2012 ◽  
Author(s):  
Dorota Kozanecka
Keyword(s):  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Experimental Investigations ◽  
Flexible Rotor

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 The Active Magnetic Bearing Enables Optimum Damping of Flexible Rotor

1984 ◽  
Author(s):  
Helmut Habermann ◽  
Maurice Brunet
Keyword(s):  
Control System ◽  
Rotation Axis ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Flexible Rotor ◽  
Mechanical Contact ◽  
Electronic Control System ◽  
Electromagnetic Coils ◽  
Automatic Balancing ◽  
Ferromagnetic Ring

The active magnetic bearing is based on the use of forces created by a magnetic field to levitate the rotor without mechanical contact between the stationary and moving parts. A ferromagnetic ring fixed on the rotor “floats” in the magnetic fields generated by the electromagnets, which are mounted as two sets of opposing pairs. The current is transmitted to the electromagnetic coils through amplifiers. The four electromagnets control the rotor’s position in response to the signals transmitted from the sensors. The rotor is maintained in equilibrium under the control of the electromagnetic forces. Its position is determined by means of sensors which continuously monitor any displacements through an electronic control system. As in every control system, damping of the loop is provided by means of a phase advance command from one or more differenciating circuits of the position error signal. The capability of modifying the electromagnetic force both in terms of amplitude and phase leads to the benefit of specific properties for the application, in particular: - automatic balancing characterized by the rotation of the moving part around its main axis of inertia, and not around the axis of the bearings allowing operation without vibrations, - adjustable damping of the suspension allowing easy passing of the critical speeds of the rotor, - high and adjustable stiffness yielding maximum accuracy of rotor equilibrium position, - permanent diagnosis of machine operation due to the knowledge of all rotation characteristics (speed, loads on the bearings, position of the rotation axis, eccentricity, out-of-balance, disturbance frequency).

scholarly journals Transient Response Technique Applied to Active Magnetic Bearing Machinery During Rotor Drop

1996 ◽  
Vol 118 (2) ◽  
pp. 154-163 ◽  
Author(s):  
T. Ishii ◽  
R. Gordon Kirk
Keyword(s):  
Transient Response ◽  
New Technology ◽  
Contact Point ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Flexible Rotor ◽  
Theoretical Formulation ◽  
Rolling Element ◽  
Bearing Design ◽  
Amb System

The active magnetic bearing (AMB) is a relatively new technology which has many advantages compared with conventional bearing design. In an AMB system, the rolling-element back-up bearings are indispensable to protect the magnetic bearing rotor and stator, and other stationary seals along the rotor shaft. In this paper, a theoretical formulation is proposed and solved numerically to examine the transient response of the flexible rotor, from the time just previous to when the AMB shuts down and including the rotor drop onto the back-up bearing. The backward whirl of the rotor, which may lead to the destructive damage of the machinery, has been analytically predicted at very light support damping and very high support damping. Also, the vibration due to the nonlinearity of the contact point geometry has been included in the analysis. The influence of the support damping on the displacement of the disk and also the contact force between the journal and the inner-race of the back-up bearing have been computed for various rotor system parameters. By comparing these results with the optimum support damping for the simple flexible rotor model, it is shown that this support damping optimization can be applicable for specifying the required optimum range of support damping for the back-up bearings of AMB systems.

A Field Balancing Technique Based on Virtual Trial-Weights Method for a Magnetically Levitated Flexible Rotor

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Yingguang Wang ◽  
Jiancheng Fang ◽  
Shiqiang Zheng
Keyword(s):  
High Efficiency ◽  
Notch Filter ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
New Method ◽  
Mode Shapes ◽  
Flexible Rotor ◽  
Magnetically Levitated ◽  
Balancing Efficiency ◽  
The Impact

For a magnetically levitated flexible rotor (MLFR), the amount of residual imbalance not only generates undesired vibrations, but also results in excessive bending, which may cause it hit to the auxiliary bearings. Thus, balancing below the critical speed is essential for the MLFR to prevent the impact. This paper proposes a balancing method of high precision and high efficiency, basing on virtual trial-weights. First, to reduce the computed error of rotor's mode shapes, a synchronous notch filter is inserted into the active magnetic bearing (AMB) controller, achieving a free support status. Then, AMBs provide the rotor with the synchronous electromagnetic forces (SEFs) to simulate the trial-weights. The SEFs with the initial angles varying from 0 deg to 360 deg in the rotational frame system result in continuous changes in the MLFR's deflection. Last, correction masses are calculated according to the changes. Compared to the trail-weights method, the new method needs not test-runs, which improves the balancing efficiency. Compared to the no trail-weights method, the new method does not require a precise model of the rotor-bearing system, which is difficult to acquire in the real system. Experiment results show that the novel method can reduce the residual imbalance effectively and accurately.

The Application of Reconfigurable Logic to Active Magnetic Bearing Controller

2009 ◽  
Author(s):  
Zbigniew Kulesza
Keyword(s):  
Integrated Circuit ◽  
Dynamic Performance ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Experimental Investigations ◽  
Control Law ◽  
Reconfigurable Logic ◽  
Control Laws ◽  
Pid Algorithm ◽  
Point Representation

The article presents the main problems of implementing the PID control law in the reconfigurable logic, namely FPGA integrated circuit. The consecutive steps of discretizing and choosing the fixed-point representation of the continuous, floating-point PID algorithm are described. The FPGA controller is going to be used in the active hetero-polar magnetic bearings system consisting of two radial and one axial bearings. The results of the experimental investigations of the controller are presented. The dynamic performance of the controller is better when compared with the dSPACE controller, that was used so far. The designed hardware and software, the developed implementation procedure and the experience acquired during this stage of the whole project are going to be used during the implementation of more sophisticated control laws (e.g. H∞ robust) in the FPGA for AMB controllers.

scholarly journals Improvement of flexible rotor/active magnetic bearings system performance using pi-d control

2020 ◽  
Vol 40 (2) ◽  
pp. 112-123
Author(s):  
Adis Muminovic ◽  
Sanjin Braut ◽  
Adil Muminovic ◽  
Isad Saric ◽  
Goranka Štimac Rončević
Keyword(s):  
Pid Control ◽  
Real Life ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
System Response ◽  
Active Magnetic Bearings ◽  
Flexible Rotor ◽  
Notch Filters ◽  
Common Control

Proportional–integral–derivative (PID) control is the most common control approach used to control active magnetic bearings system, especially in the case of supporting rigid rotors. In the case of flexible rotor support, the most common control is again PID control in combination with notch filters. Other control approaches, known as modern control theory, are still in development process and cannot be commonly found in real life industrial application. Right now, they are mostly used in research applications. In comparison to PID control, PI-D control implies that derivate element is in feedback loop instead in main branch of the system. In this paper, performances of flexible rotor/active magnetic bearing system were investigated in the case of PID and PI-D control, both in combination with notch filters. The performances of the system were analysed using an analysis in time domain by observing system response to step input and in frequency domain by observing a frequency response of sensitivity function.

Aseismic Vibration Control of Flexible Rotors Using Active Magnetic Bearing

2001 ◽  
Vol 124 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Osami Matsushita ◽  
Toshio Imashima ◽  
Yoshitaka Hisanaga ◽  
Hiroki Okubo
Keyword(s):  
Seismic Waves ◽  
Control Method ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Flexible Rotor ◽  
Feed Forward Control ◽  
Kobe Earthquake ◽  
Flexible Rotors ◽  
Additional Control ◽  
Modal Model

The wide application of active magnetic bearing (AMB) requires an aseismic evaluation with respect to AMB rotor vibrations caused by actual earthquakes. A flexible rotor supported by AMB is selected for this purpose. A shaking simulation obtained using the quasi-modal model and the actual Kobe earthquake was completed. A corresponding test rotor was excited by seismic waves and the resulting vibration was measured for the vibration evaluation. In order to reduce the response severity against earthquakes, we propose an additional feed forward control method which is proportional to the signal detected by the accelerometers attached to the bearing housings. Since this additional control can cancel rotor vibration generated by the earthquakes, AMB rotor vibrations are successfully suppressed at a low level.

Sign in / Sign up

Export Citation Format

Share Document