Frequency-Varying Current Harmonics for Active Magnetic Bearing via Multiple Resonant Controllers

The rotating machinery suspended by an active magnetic bearing (AMB) system always suffers from rotor mass imbalance and sensor runout disturbances, which lead to the periodic fluctuations in control currents. This paper presents a novel multiple resonant controllers (MRC) for an AMB system to suppress the multifrequency current harmonics in the presence of variable rating speed. The principle and structure of the plug-in MRC used for current harmonics suppression in the AMB system is discussed. The design of the proposed MRC, using the progressively tuning and segmentation switch strategy, is given. The proposed design method for the MRC can achieve the balance between good stability and harmonics suppression precision. As well, the robustness of the overall system is systematically analyzed for the entire operational speed range. Simulation and experimental results for current fluctuations and multifrequency vibration forces on a magnetically suspended flywheel validate the effectiveness of the proposed method.