Modal Testing and Suboptimal Vibration Control of Flexible Rotor Bearing System by Using a Magnetic Bearing

1992 ◽  
Vol 114 (2) ◽  
pp. 244-252 ◽  
Author(s):  
Chong-Won Lee ◽  
Jong-Sun Kim
Keyword(s):  
Output Feedback ◽  
Magnetic Bearing ◽  
Feedback Controller ◽  
Reduced Order Model ◽  
Flexible Rotor ◽  
Order Model ◽  
Reduced Order ◽  
Output Feedback Controller ◽  
Rotor Bearing ◽  
Bearing System

A suboptimal output feedback controller is designed based on a reduced order model and applied to a flexible rotor bearing system in order to control the unstable or lightly damped vibrations occurring during operation. The reduced order model is a truncated modal equation of the distributed parameter system obtained through the singular perturbation. The instability problem arising from the spillover effects caused by the uncontrolled high frequency modes is prevented through the constrained optimization by incorporating the spillover term into the performance index. The application of the matrix minimum principle yields a set of matrix equation similar to the unconstrained output feedback controller. The efficiency of the proposed method is demonstrated experimentally with a flexible rotor by using a magnetic bearing.

A Balanced IIRS Model for Investigating the Dynamics of Damped Rotor Bearing System

2014 ◽  
Author(s):  
S. Chandraker ◽  
H. Roy
Keyword(s):  
Symmetric Matrices ◽  
Internal Damping ◽  
Order Model ◽  
Complex Behaviour ◽  
Campbell Diagram ◽  
Reduced Order ◽  
Rotor Bearing ◽  
The Matrix ◽  
Rate Plot ◽  
Bearing System

In this paper the application of the balanced Iterative Improved Reduction model techniques to complex rotor-bearing systems is investigated. It is demonstrated that, Iterative Improved Reduction System (IIRS) improves the matrix reductions by ensuring that the transformation matrix for each reduction is optimized. This reduction technique also benefices the problem due to skew symmetric matrices, which arises for inclusion of gyroscopic effect and internal damping. Numerical examples are solved to demonstrate the validity and efficiency of the reduced order model in representing the dynamics of the actual rotor system. Under these conditions, the complex behaviour of the rotor-shaft is studied to get an insight of the dynamic characteristics of the system, in terms of Campbell Diagram, Decay rate plot and Unbalance Response. Many researchers adopted different methodology for obtaining the model reduction but their work is limited up to undamped system. This work is started by motivation of the absentia of work for damped rotor bearing system.

Optimal Output Feedback Control of Asymmetric Systems Using Complex Modes

1993 ◽  
Vol 115 (2) ◽  
pp. 307-313 ◽  
Author(s):  
G. W. Fan ◽  
H. D. Nelson ◽  
M. P. Mignolet
Keyword(s):  
Feedback Control ◽  
Output Feedback ◽  
Output Feedback Control ◽  
High Order ◽  
Reduced Order Model ◽  
Control Procedure ◽  
Order Model ◽  
Complex Mode ◽  
Reduced Order ◽  
Complex Modes

A Linear Quadratic Regulator (LQR)-based least-squares output feedback control procedure using a complex mode procedure is developed for the optimal vibration control of high-order asymmetric discrete system. An LQ Regulator is designed for a reduced-order model obtained by neglecting high-frequency complex modes of the original system. The matrix transformations between physical coordinates and complex mode coordinates are derived. The complex mode approach appears to provide more accurate reduced-order models than the normal mode approach for asymmetric discrete systems. The proposed least-squares output feedback control procedure takes advantage of the fact that a full-state feedback control is possible without using an observer. In addition, the lateral vibration of a high-order rotor system can be effectively controlled by monitoring one single location along the rotor shaft, i.e., the number of measured states can be much less than the number of eigenvectors retained in producing the reduced-order model while acceptable performance of the controller is maintained. The procedure is illustrated by means of a 52 degree-of-freedom finite element based rotordynamic system. Simulation results show that LQ regulators based on a reduced-order model with 12 retained eigenvalues can be accurately approximated by using feedback of four measured states from one location along the rotor shaft. The controlled and uncontrolled transient responses, using various numbers of measured states, of the original high-order system are shown. Comparisons of reduced-order model results using normal modes and complex modes are presented. The spillover problem is discussed for both collocated and noncollocated cases based on this same example.

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