Harmonic vibration moment suppression using hybrid repetitive control for active magnetic bearing system

2021 ◽  
pp. 107754632110109
Author(s):  
Peiling Cui ◽  
Liang Du ◽  
Xinxiu Zhou ◽  
Jinlei Li ◽  
Yanbin Li ◽  
...  
Keyword(s):  
Control Method ◽  
Hybrid Control ◽  
Repetitive Control ◽  
Control Object ◽  
Sampling Period ◽  
Response Speed ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Harmonic Vibration ◽  
Bearing System

The active magnetic bearing system exhibits mass imbalance and sensor runout which cause the system to generate harmonic vibration force and moment. Repetitive control is an effective method to eliminate such harmonic vibration. Traditional repetitive control will eliminate all of the harmonic frequency components. However, in a practical system, the odd harmonic components usually dominate. Meanwhile, the existing method only suppresses the vibration force in the magnetic bearing system, and there is little research on the suppression of moment. Aiming at these problems, the harmonic vibration moment of the active magnetic bearing system is taken as the control object. This study investigates a hybrid control method that combines a second-order odd harmonic repetitive control with finite-dimensional repetitive control. And the virtual variable sampling is applied to construct any virtual sampling period in the proposed method, which effectively solves the problem of non-integer delay of digital repetitive control. The stability of the active magnetic bearing system is analyzed. The experimental results show that this method has faster response speed and better robustness when the frequency fluctuates.

Isotropic Optimal Control of Active Magnetic Bearing System

1996 ◽  
Vol 118 (4) ◽  
pp. 721-726 ◽  
Author(s):  
Cheol-Soon Kim ◽  
Chong-Won Lee
Keyword(s):  
Optimal Control ◽  
System Analysis ◽  
Control Method ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Control Effort ◽  
Response Component ◽  
Unbalance Response ◽  
Control Scheme ◽  
Bearing System

As a new rotor control scheme, isotropic control of weakly anisotropic rotor bearing system in complex state space is proposed, which utilizes the concepts on the eigenstructure of the isotropic rotor system. Advantages of the scheme are that the controlled system always retains isotropic eigenstructure, leading to circular whirling due to unbalance and that it is efficient for control of unbalance response. And the system analysis and controller design becomes simple and yet comprehensive since the order of the matrices treated in the complex domain approach is half of that in the real approach. The control scheme is applied to a rigid rotor-active magnetic bearing system which is digitally controlled and the control performance is investigated experimentally in relation to unbalance response and control energy. It is found that the isotropic optimal control method, which essentially eliminates the backward unbalance response component, is more efficient than the conventional optimal control in that it gives smaller major whirl radius and yet it often requires less control effort.

scholarly journals Disturbance and uncertainty estimator-based cascaded position-current controller for active magnetic bearing system

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983535 ◽  
Author(s):  
Yao-Nan Wang ◽  
Tran Minh Hai
Keyword(s):  
Control Method ◽  
Sliding Mode ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
System State ◽  
Control Loop ◽  
Current Controller ◽  
Highly Nonlinear ◽  
Uncertainty Estimator ◽  
Bearing System

This article presents a robust control method; all of the unknown disturbances and uncertainty values will be rejected. Suspension of active magnetic bearing system is aimed to figure out that the proposed control method is implementable for highly nonlinear unstable system. First, system state is described by dynamic model, with unknown lump of uncertainty value. Subsequently, the cascade control with inner and outer loops is defined by sliding mode control based on disturbance and uncertainty estimator. The outer control loop is used to force the system state converge on the predefined surface, while inner control loop is used to control the current of electrical part of the system. Finally, the simulation results show that the proposed control method is good at tracking trajectory.

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.

scholarly journals Development and Experimental Validation of Auxiliary Rolling Bearing Models for Active Magnetic Bearings (AMBs) Applications

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Anna Tangredi ◽  
Enrico Meli ◽  
Andrea Rindi ◽  
Alessandro Ridolfi ◽  
Pierluca D’Adamio ◽  
...  
Keyword(s):  
Load Capacity ◽  
Critical Phenomenon ◽  
Magnetic Bearing ◽  
Design Tool ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Short Period ◽  
Auxiliary Bearing ◽  
Bearing System

Nowadays, the search for increasing performances in turbomachinery applications has led to a growing utilization of active magnetic bearings (AMBs), which can bring a series of advantages thanks to their features: AMBs allow the machine components to reach higher peripheral speeds; in fact there are no wear and lubrication problems as the contact between bearing surfaces is absent. Furthermore, AMBs characteristic parameters can be controlled via software, optimizing machine dynamics performances. However, active magnetic bearings present some peculiarities, as they have lower load capacity than the most commonly used rolling and hydrodynamic bearings, and they need an energy source; for these reasons, in case of AMBs overload or breakdown, an auxiliary bearing system is required to support the rotor during such landing events. During the turbomachine design process, it is fundamental to appropriately choose the auxiliary bearing type and characteristics, because such components have to resist to the rotor impact; so, a supporting design tool based on accurate and efficient models of auxiliary bearings is very useful for the design integration of the Active Magnetic Bearing System into the machine. This paper presents an innovative model to accurately describe the mechanical behavior of a complete rotor-dynamic system composed of a rotor equipped with two auxiliary rolling bearings. The model, developed and experimentally validated in collaboration with Baker Hughes a GE company (providing the test case and the experimental data), is able to reproduce the key physical phenomena experimentally observed; in particular, the most critical phenomenon noted during repeated experimental combined landing tests is the rotor forward whirl, which occurs in case of high friction conditions and greatly influences the whole system behavior. In order to carefully study some special phenomena like rotor coast down on landing bearings (which requires long period of time to evolve and involves many bodies and degrees of freedom) or other particular events like impacts (which occur in a short period of time), a compromise between accuracy of the results and numerical efficiency has been pursued. Some of the elements of the proposed model have been previously introduced in literature; however the present work proposes some new features of interest. For example, the lateral and the axial models have been properly coupled in order to correctly reproduce the effects observed during the experimental tests and a very important system element, the landing bearing compliant suspension, has been properly modelled to more accurately describe its elastic and damping effects on the system. Furthermore, the model is also useful to characterize the frequencies related to the rotor forward whirl motion.

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