4. Modal Control of Magnetic Suspended Rotors

The present work is devoted to the conception of a Systematic Approach for the Robust Design of an Active Modal Controller applied to Supercritical Rotors supported by Magnetic Bearings. For this purpose, all the steps involved in the design of a robust controller based on the multimodel eigenstructure assignment technique is discussed. The first step is the development of a numeric/computer model in MATLAB/SIMULINK environment, based on the specifications of the test rig used in the experimental part of this work (which are provided by the test rig manufacturer). The first stage of the controller synthesis has to do with the specification of all design requirements. Then, all the phases involved in the process of the multimodel eigenstructure assignment are addressed in detail, starting from the determination of the plant dominant poles, so that, finally, the model based analysis of the system stability and performance are studied. The performance of the controller was evaluated through the analysis of its closed loop Transfer Functions and by investigating the unbalance response of the rotating system. It is worth mentioning that for all presented investigations, comparisons between two architectures of the controller, namely, the modal controller and the PI controller were performed, accordingly. The following natural step is the analysis of the correlation of theoretical and experimental results for validation purposes, which will be presented in a further contribution.