Robust control of an active magnetic bearing system using H_∞ and disturbance observer-based control

Abstract

Active magnetic bearing systems (AMBs) have many potential industrial applications where extremely fast and accurate operations are required. However, AMBs are often subject to disturbances in the form of synchronous vibrations due to unmodeled dynamics such as the rotor mass-imbalance and centrifugal forces while the rotor is in rotation. Several methods such as variable notch filters, gain scheduling controllers, and linear parameter varying controllers have been proposed recently to reject the disturbances while the system is operating at high rotational speeds. These methods are practical only if the frequencies of these sinusoidal-like disturbances are directly measurable or accurately known in advance. In this paper, a hybrid control scheme comprised of a feedback H∞ controller and an inner-loop disturbance observer-based control is proposed. The effectiveness of this control scheme is verified by simulation and real-time experiments on an AMB system. Both constant and sinusoidal disturbances are taken into consideration while the rotor is stationary as well as while it is rotating at different speeds. The results demonstrate that the proposed hybrid control scheme exhibits significantly improved performance in comparison to single-loop controllers in the presence of unknown but bounded disturbances.

AMB flywheel integration with photovoltaic system for household purpose – modelling and analysis

“…In order to provide flywheel high rotational speed operation the robustness of the control system is essential. The AMB system identification with disturbance observer-based control is one of common approach [15,16]. In embodiments of the AMB flywheel the electric machine works alternately both as a generator and as a motor.…”

Nonlinear Control of an Active Magnetic Bearing with Output Constraint

“…Relation (12) means that the speed estimation error exponentially converges to zero and the convergence speed depends on k. By using the speed observer (6), the state space model of the AMB system can be rewritten as…”

“…Through a set of numerical simulations, the state feedback control shows its strength in comparison with output feedback and deadbeat controls. Inspired by loop shaping properties of H ∞ optimization and disturbances rejection ability of the disturbance observer-based controller, [12] successfully develop a hybrid controller whose effectiveness are verified via simulations and real-time experiments. By investigating strong nonlinearity of 3-poles AMB, a feedback linearization law is composed in [13].…”

Analysis of Different Vibration Control Strategies for Soft Mounted Induction Motors with Sleeve Bearings Using Active Motor Foot Mounts

“…Therefore, the idea is to use active vibration control, which is a very powerful instrument, to optimize the vibration behaviour [6] [7] [8] [9]. For rotating machinery sometimes active magnetic bearings are used, especially for high speed applications, and have been optimized during time [10] [11] [12] [13] [14]. But also actuators-used as active mounts-have been investigated, to optimize the vibration behaviour of rotating machinery [15] [16] [17] [18] [19].…”