A Method for Controlling Multi-Frequency Unbalance Response of a Rotor with Magnetically Levitated Dynamic Absorber

Many design difficulties in rotor vibration control can be solved by means of electro-magnetically-levitated dynamic absorber. The absorber presented here, not rotating with rotor, can be designed in practice, and it need not to be placed at the bearings. Thus, both the static functions and the dynamic functions of rotor system can be considered simultaneously, and the design difficulties caused by centrifugal force can be overcome also. Therefore, the design conception is of great value for practical use in engineering. The control system of an electro-magnetically-levitated dynamic absorber has been designed using the theory of output regulation. The main aim of the control system is to reduce the unbalance response of the rotor equipped with the absorber to zero at several specified frequencies and to a non-resonant level at other frequencies. The effectiveness of the control method and the feasibility of the absorber for control of rotor unbalance response have been shown by numerical simulations on the frequency characteristics.