Experimental Research on Unbalance Control of Active Magnetic Bearings

Two unbalance control methods, General Notch Filter (GNF) and LMS (least mean square), for active magnetic bearings (AMBs) were applied to a high speed rotor supported by AMBs. The rotor operation was greatly influenced by a large residual unbalance in the rotor and some low frequency vibration modes from the structure of the rotor system. GNF was used to help the rotor to increase its dynamic balance efficiency with two different methods. To achieve a better unbalance cancellation effect for the rotor in a large rotation speed range, GNF and LMS methods were combined in a single unbalance controller and performed in different speed ranges. A simple but effective method was used to achieve a smooth switching of the two methods. Corresponding experiment results are provided. GNF algorithm increased the balance efficiency. The smooth switching of GNF and LMS was successful and the unbalance control effects were improved.