scholarly journals Sliding Mode Output Feedback Control of a Flexible Rotor via Magnetic Bearings

1998 ◽  
Author(s):  
A. S. Lewis ◽  
A. Sinha ◽  
K. W. Wang
Keyword(s):  
Differential Equations ◽  
Sliding Mode ◽  
Output Feedback Control ◽  
Angular Speed ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Control Parameters ◽  
Flexible Rotor ◽  
Rotor Imbalance ◽  
Feedback Algorithm

A sliding mode feedback algorithm is proposed to control the vibration of a flexible rotor supported by magnetic bearings. It is assumed that the number of states is greater than the number of sensors. A mathematical model of the rotor/magnetic bearing system is presented in terms of partial differential equations. These equations are then discretized into a finite number of ordinary differential equations through Galerkin’s method. The sliding mode control law is designed to be robust to rotor imbalance and transient disturbances. A boundary layer is introduced around each sliding hyperplane to eliminate the chattering phenomenon. The results from numerical simulations are presented which not only corroborate the validity of the proposed controller, but also show the effects of various control parameters as a function of the angular speed of the rotor. In addition, results are presented that indicate how the current required by the magnetic bearings is affected by control parameters and the angular speed of the rotor.

scholarly journals Sliding Mode Output Feedback Control of a Flexible Rotor Supported by Magnetic Bearings

2001 ◽  
Vol 7 (2) ◽  
pp. 117-129 ◽  
Author(s):  
A. S. Lewis ◽  
A. Sinha ◽  
K. W. Wang
Keyword(s):  
Differential Equations ◽  
Sliding Mode ◽  
Output Feedback Control ◽  
Angular Speed ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Control Parameters ◽  
Flexible Rotor ◽  
Transient Disturbances ◽  
Feedback Algorithm

A new sliding mode feedback algorithm is applied to control the vibration of a flexible rotor supported by magnetic bearings. It is assumed that the number of states is greater than the number of sensors. A mathematical model of the rotor]magnetic bearing system is presented in terms of partial differential equations. These equations are then discretized into a finite number of ordinary differential equations through Galerkin’s method. The sliding mode control law is designed to be robust to rotor unbalance and transient disturbances. A boundary layer is introduced around each sliding hyperplane to eliminate the chattering phenomenon. The results from numerical simulations are presented that not only corroborate the validity of the proposed controller, but also show the effects of various control parameters as a function of the angular speed of the rotor. In addition, results are presented that indicate how the current required by the magnetic bearings is affected by control parameters and the angular speed of the rotor.

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.

Adaptive Virtual Autobalancing for a Rigid Rotor With Unknown Mass Imbalance Supported by Magnetic Bearings

1998 ◽  
Vol 120 (2) ◽  
pp. 557-570 ◽  
Author(s):  
Kai-Yew Lum ◽  
Vincent T. Coppola ◽  
Dennis S. Bernstein
Keyword(s):  
Physical Model ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Rigid Rotor ◽  
Compensation Scheme ◽  
Elastic Suspension ◽  
Single Plane ◽  
Rotor Imbalance ◽  
Line Identification ◽  
On Line

The objective of this paper is to describe an imbalance compensation scheme for a rigid rotor supported by magnetic bearings that performs on-line identification of rotor imbalance and allows imbalance cancellation under varying speed of rotation. The proposed approach supplements existing magnetic bearing controls which are assumed to achieve elastic suspension of the rotor. By adopting a physical model of imbalance and utilizing measurements of the spin rate, the proposed algorithm allows the computation of the necessary corrective forces regardless of variations in the spin rate. Convergence of the algorithm is analyzed for single-plane balancing, and is supported by simulation in single- and two-plane balancing, as well as by experimental results in single-plane implementation.

Fault Tolerant Magnetic Bearings

1999 ◽  
Vol 121 (3) ◽  
pp. 504-508 ◽  
Author(s):  
E. H. Maslen ◽  
C. K. Sortore ◽  
G. T. Gillies ◽  
R. D. Williams ◽  
S. J. Fedigan ◽  
...  
Keyword(s):  
Fault Tolerance ◽  
High Speed ◽  
Fault Tolerant ◽  
High Capacity ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Flexible Rotor ◽  
Variable Reluctance ◽  
Modular Redundancy ◽  
Bearing System

A fault tolerant magnetic bearing system was developed and demonstrated on a large flexible-rotor test rig. The bearing system comprises a high speed, fault tolerant digital controller, three high capacity radial magnetic bearings, one thrust bearing, conventional variable reluctance position sensors, and an array of commercial switching amplifiers. Controller fault tolerance is achieved through a very high speed voting mechanism which implements triple modular redundancy with a powered spare CPU, thereby permitting failure of up to three CPU modules without system failure. Amplifier/cabling/coil fault tolerance is achieved by using a separate power amplifier for each bearing coil and permitting amplifier reconfiguration by the controller upon detection of faults. This allows hot replacement of failed amplifiers without any system degradation and without providing any excess amplifier kVA capacity over the nominal system requirement. Implemented on a large (2440 mm in length) flexible rotor, the system shows excellent rejection of faults including the failure of three CPUs as well as failure of two adjacent amplifiers (or cabling) controlling an entire stator quadrant.

Analysis of Control Method for Magnetic Bearing Systems

2017 ◽  
Vol 21 (3) ◽  
pp. 527-533
Author(s):  
Gang Huang ◽  
◽  
Xiaolin Yang ◽  
Jinhua She ◽  
Weihua Cao ◽  
...  
Keyword(s):  
High Speed ◽  
Control Method ◽  
Sliding Mode ◽  
Magnetic Bearing ◽  
Network Control ◽  
Neural Network Control ◽  
Flexible Rotor ◽  
Stable Suspension ◽  
Controller Performance ◽  
Network Control Systems

Magnetic bearing systems have attracted extensive attention in the fields of high speed, spotless area, vacuum space, etc. System performance depends largely on the control link, and it has become a research focus to improve controller performance to ensure high precision stable suspension and high anti-interference capability. This paper considers optimized, sliding mode, robust, fuzzy, and neural network control systems and assesses their research status and limitations for magnetic bearing systems. Algorithms for proposed vibration and high speed flexible rotor controls are illustrated. Finally, development trends for control technology of magnetic bearing systems are discussed.

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