Force Free Control in Active Magnetic Bearing Systems for the Magnetically Suspended Compound Molecule Pump

A force free control method is studied based on the active magnetic bearings (AMBs) system of the magnetically suspended compound molecule pump. This method uses the feedforward strategy. The output signals generated with the least mean square (LMS) algorithm are the same as synchronous disturbances, which are caused by unbalance forces. So through this approaches, the controller need not respond to synchronous disturbances. This method can let the rotor rotate around its inertia axis and eliminate the synchronous disturbances of the currents in the electromagnet windings to significantly attenuate the mechanical vibration of the shell. The experimental results verify that the proposed approach is significantly minimized the amplitude of the shell vibration of the magnetically suspended compound molecule pump, which will provide good experience and design references for the future application of the AMBs in the molecule pump.