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.

Isotropic Control of Rotor Bearing System

1993 ◽  
Author(s):  
Cheol-Soon Kim ◽  
Chong-Won Lee
Keyword(s):  
State Space ◽  
Transient Response ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Control Performance ◽  
Complex State ◽  
Unbalance Response ◽  
Control Scheme ◽  
Rotor Bearing ◽  
Bearing System

Abstract A new rotor control scheme, the isotropic control of anisotropic rotor bearing system in complex state space, is proposed, which utilizes the concepts on the eigenstructure of the isotropic rotor system. Then the control scheme is applied to an active magnetic bearing system and the control performance is investigated in relation to control energy, transient response, and unbalance response. In particular, it is shown that the proposed method is efficient for control of unbalance response.

scholarly journals Nonlinear Dynamics and Motion Bifurcations of the Rotor Active Magnetic Bearings System with a New Control Scheme and Rub-Impact Force

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1502
Author(s):  
Nasser Abul-Fadeel Saeed ◽  
Emad Mahrous ◽  
Emad Abouel Nasr ◽  
Jan Awrejcewicz
Keyword(s):  
Control Method ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Rotating Disc ◽  
Nonlinear Dynamical ◽  
Dynamic Friction Coefficient ◽  
Impact Forces ◽  
Control Scheme ◽  
The Impact ◽  
First Time

This article is dedicated to investigating the nonlinear dynamical behaviors of the 8-pole rotor active magnetic bearing system. The rub and impact forces between the rotating disc and the pole-legs are included in the studied model for the first time. A new control scheme based on modifying the 8-pole positions has been introduced. The proposed control methodology is designed such that four poles only are located in the horizontal and vertical directions (i.e., in +X,+Y,−X,−Y directions), while the other four poles are inserted in a way such that each pole makes 45° with two of the axes +X,+Y,−X,−Y. The control currents in the horizontal and vertical poles are suggested to be proportional to both the velocity and displacement of the rotor in the horizontal and vertical directions, respectively, while the control currents in the inclined poles are proposed to be dependent on the combination of both the displacement and velocity of the rotor in the horizontal and vertical directions. Accordingly, the whole-system mathematical model is derived. The derived discontinuous dynamical system is analyzed employing perturbation methods, Poincare maps, bifurcation diagrams, whirling orbits, and frequency spectrum. The obtained results demonstrated that the controller proportional control gain can play a significant role in changing the vibratory behaviors of the system, where the proposed control method can behave either as a cartesian control strategy or as a radial control one depending on the magnitude of the proportional gain. In addition, it is found that the rotor system can vibrate with periodic, periodic-n, quasiperiodic, or chaotic motion when the rub and/or impact forces occur. Moreover, it is reported for the first time that the rotor-AMB can oscillate symmetrically in X and Y directions either in full annular rub mode or quasiperiodic partial rub mode depending on the impact stiffness coefficient and the dynamic friction coefficient.

An anti-windup control strategy to actuator saturating input voltage for active magnetic bearing system

2016 ◽  
Vol 35 (3) ◽  
Author(s):  
Avadh Pati ◽  
Richa Negi
Keyword(s):  
Control Strategy ◽  
Pid Control ◽  
Input Voltage ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Region Of Attraction ◽  
Control Scheme ◽  
Amb System ◽  
Voltage Saturation ◽  
Bearing System

Purpose The active magnetic bearing is highly nonlinear and unstable system. In general most of physical systems, conventional PID control strategies are employed for their stable operation but the dynamics of the system are influenced by input voltage saturation that degrades the performance of the system. The conventional PID control scheme does not work properly alone. In such a situation, PID faces windup phenomenon that leads to instability in the system. To overcome this problem, an anti-windup control scheme leads to stable and smooth operation of active magnetic bearing system. Design/methodology/approach The proposed anti-windup control strategy is based on dynamic output feedback that is applied on linearized active magnetic bearing (AMB) system to stabilize and avoid the input voltage saturation effect in the actuator. Findings An anti-windup controller is designed for active magnetic bearing system in presence of input voltage saturation. The stability of AMB system with anti-windup controller is derived in sense of Lyapunov and expressed as linear matrix inequality problem for AMB system and the designed anti-windup controller also enlarges the region of attraction of considered AMB system. Originality/value T-S fuzzy technique is used for obtaining local linear model of nonlinear active magnetic bearing system for easy and simple implementation of anti-windup control scheme. In proposed methodology the region of attraction for anti-windup compensator is also discussed. The effectiveness of proposed method is verified by the numerical simulation results for considered active magnetic bearing system and domain of attraction or stability region of closed loop AMB system are also calculated using Eigen Value Optimization technique for both the cases such as with and without anti-windup controller. The comparative result and the contribution of proposed control strategy are also discussed.

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.

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.

Pseudospectral method-based optimal control for a nonlinear five degree of freedom active magnetic bearing system

2021 ◽  
pp. 014233122098653
Author(s):  
Sudipta Saha ◽  
Arunava Banerjee ◽  
Syed Muhammad Amrr ◽  
Mashuq un Nabi
Keyword(s):  
Optimal Control ◽  
Control Method ◽  
Pseudospectral Method ◽  
Magnetic Bearing ◽  
Degree Of Freedom ◽  
Active Magnetic Bearing ◽  
Physical Contact ◽  
Computational Time ◽  
Optimal Control Strategy ◽  
Amb System

Active magnetic bearings (AMB) are used to suspend the rotor freely inside the stator to avoid any physical contact between them. Thus, it helps in significantly reducing the wear and tear that may cause a system breakdown. With the advancement of power electronics and the implementation of advanced control techniques, the use of AMB in industrial applications has increased. This paper proposes an optimal control strategy for the five degree of freedom (DOF) AMB system. The time-energy consumption of input is minimized by the application of a relatively new optimal control method called the pseudospectral method (PSM). Since the AMB is a nonlinear system, therefore the implementation of classical optimal control strategies becomes challenging. Thus, the PSM first transforms the optimal control problem at non-uniform nodes and converts it into a nonlinear programming problem, which is relatively easier to tackle. The PSM, as demonstrated in this paper, is able to find optimal solutions using relatively fewer grid points which in turn reduces the computational time and converges to the solution faster. The simulation analysis for the AMB system using two different types of PSM, that is, Legendre PSM and the Chebyshev PSM illustrates the optimal performance of the proposed strategy.

Sign in / Sign up

Export Citation Format

Share Document