Flexible Rotor System Identification and Vibration Control by Using a Magnetic Bearing

Experimental modal testings are performed in order to identify the modal parameters which are essential to model building of the open loop system of the rotors. By separating the forward and backward modes in two sided frequency domain, it is shown that accurate modal parameters can be obtained, resulting in accurate modelling. It is shown that the modal testing method allows clear physical insight into the behaviors of the forward and backward modes, particularly in the case of the isotropic rotor treated in this research. A suboptimal output feedback controller is designed based on a reduced order model and is applied to a flexible rotor. The instability problem arising from the spillover effects caused by the uncontrolled high frequency modes is prevented through the constrained optimization by incorporating the spillover term into the performance index. The efficiency of the proposed identification and control method is demonstrated experimentally with a flexible rotor by using a magnetic bearing as a force actuator.