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.

Adaptive hybrid control of unbalanced vibrations of a rotor/active magnetic bearing system with coupling misalignment using low cost instrumentation

2019 ◽  
Vol 25 (15) ◽  
pp. 2151-2174
Author(s):  
Rajiv Kumar Vashisht ◽  
Qingjin Peng
Keyword(s):  
Hybrid Control ◽  
Frequency Estimation ◽  
Low Cost ◽  
Active Noise Control ◽  
Notch Filter ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Flexible Rotor ◽  
Adaptive Notch Filter ◽  
Bearing System

An adaptive hybrid controller is proposed for reducing the unbalanced vibration response of a flexible rotor/active magnetic bearing system. It is observed that conventional adaptive feedforward controller (AFFC) normally used in the active noise control is very sensitive in performance for changes in rotor spin frequencies. Although frequency updating is a part of its architecture, a small practical variation in the rotor spin frequency can reduce its effectiveness drastically. A smart combination of adaptive notch filter and Goertzel filter is proposed for the frequency estimation. During changes of the rotor spin frequency, fundamental harmonics of the flexible rotor are excited. By using hybrid controllers that combine feedback control and AFFC, the amplitude of these fundamental harmonics is reduced significantly. By applying the multi-harmonic hybrid control, the multiple harmonics generated due to coupling misalignment are compensated efficiently. Fourier transform of the control signal is further used to detect the presence of the coupling misalignment.

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 The Impact Analysis of Beating Vibration for Active Magnetic Bearing

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 134104-134112 ◽  
Author(s):  
Hui Gao ◽  
Xianhai Meng ◽  
Kejun Qian
Keyword(s):  
Impact Analysis ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
The Impact

scholarly journals Research on Automatic Balance Control of Active Magnetic Bearing-Rigid Rotor System

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Yang Liu ◽  
Shuaishuai Ming ◽  
Siyao Zhao ◽  
Jiyuan Han ◽  
Yaxin Ma
Keyword(s):  
Vibration Control ◽  
Rotational Speed ◽  
Notch Filter ◽  
Magnetic Bearing ◽  
Rotor System ◽  
Vibration Response ◽  
Active Magnetic Bearing ◽  
Rigid Rotor ◽  
Phase Compensation ◽  
Synchronous Control

In this paper, in order to solve the problem of unbalance vibration of rigid rotor system supported by the active magnetic bearing (AMB), automatic balancing method is applied to suppress the unbalance vibration of the rotor system. Firstly, considering the dynamic and static imbalance of the rotor, the detailed dynamic equations of the AMB-rigid rotor system are established according to Newton’s second law. Then, in order to rotate the rotor around the inertia axis, the notch filter with phase compensation is used to eliminate the synchronous control current. Finally, the variable-step fourth-order Runge–Kutta iteration method is used to solve the unbalanced vibration response of the rotor system in MATLAB simulation. The effects of the rotational speed and phase compensation angle on the unbalanced vibration control are analysed in detail. It is found that the synchronous control currents would increase rapidly with the increase of rotational speed if the unbalance vibration cannot be controlled. When the notch filter with phase shift is used to balance the rotor system automatically, the control current is reduced significantly. It avoids the saturation of the power amplifier and reduces the vibration response of the rotor system. The rotor system can be stabilized over the entire operating speed range by adjusting the compensation phase of the notch filter. The method in the paper is easy to implement, and the research result can provide theoretical support for the unbalance vibration control of AMB-rotor systems.

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.

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