Adaptive Disturbance Rejection and Stabilization for Rotor Systems with Internal Damping

Abstract

Advanced rotor systems today consist of a lightweight rotor supported by radial active magnetic bearings (AMB). These systems are widely used in flywheel applications and in other fields where high rotational speeds are essential. Flywheels are most often made of composite materials to ensure low weight and sufficient structural strength. It has been shown in previous works that composite materials have high energy dissipation characteristics, mainly due to internal damping. In applications where the rotor speed is subcritical, this property is of low concern, whereas at supercritical speeds the effect of internal damping should not be ignored due to instability effects described in detail later. Therefore, it is essential that one must have a detailed understanding of the sources and effects of internal damping in these structures. This work addresses the application of Adaptive Disturbance Rejection (ADR) control method to deal with the rotordynamic instability caused by internal damping and synchronous vibrations caused by mass imbalance in rotor systems operating at supercritical speeds. The three modeled systems are 1) a simple Jeffcott-rotor, 2) a rigid shaft with flexible hub and 3) a slim, flexible shaft. A detailed description of the problems and the strategies for addressing them are discussed. A fixed-gain controller was also developed for each model to better compare the results to the ones from the adaptive controllers. Simulation modeling and analysis results are presented and discussed to illustrate the method and demonstrate its effectiveness.