Adaptive Inertial Autocentering of a Rigid Rotor with Unknown Imbalance Supported by Active Magnetic Bearings

An adaptive inertial autocentering method for rigid rotors with inertial mass imbalance supported by active magnetic bearings is presented. It results in rotation about the inertial center rather than the geometric center of the rotor, therefore drastically reducing the synchronous transmitted forces due to the imbalance. The adaptation algorithm can be interpreted as an observer. It provides an estimate of the inertial center position. Measurement of the rotor angle is not required. Experimental results illustrate the usefulness of such an approach. The method can be extended to operation at variable angular velocity. This is done in such a way that the stability can be discussed using the theory of linear time invariant systems. The convergence of the adaptation is made depend on the angular velocity, thus allowing fast convergence (with respect to time) at high angular velocities.