AERODYNAMIC LOADING AND MAGNETIC BEARING CONTROLLER ROBUSTNESS USING A GAIN-SCHEDULED KALMAN FILTER

Modeling or predicting aerodynamic loading effects on rotating equipme nt has been a source of concern to those who wish to examine stability or response of critical components. The rotordynamic model of the sys tem employed for such examination assumes greater importance for activ e hearings than for passive ones, if only because of the additional po tential for instability introduced by the controller. For many systems , aerodynamic loading may vary widely over the range of operation of t he bearings, and may depend on extended system variables. Thus, potent ial controllers for active magnetic bearings require sufficient robust ness or adaptation to changes in critical aerodynamic loading paramete rs, as might be embodied in cross-coupled stiffness terms for compress or impellers. Furthermore, the presence of plant or measurement noise provides additional sources of complication. Here, the previous develo pment of a nonlinear controller for a hypothetical single-stage centri fugal gas compressor is extended by comparing the compensator performa nce using a multi-variable Luenberger observer against that of a stati onary Kalman filter, both gain-scheduled for rotational speed. For. th e postulated system, it was found that the slower poles of the Kalman filter did not observably detract from controller convergence and stab ility, while predictably smoothing our the simulated sensor noise.