Harmonic Current Suppression of an AMB Rotor System at Variable Rotation Speed Based on Multiple Phase-Shift Notch Filters

An active magnetic bearing (AMB) rotor system has such advantages as no friction and active vibration control. However, harmonic current caused by mass imbalance and sensor runout of magnetically suspended rotor system will lead to harmonic vibration. The harmonic current frequency is changed with the variation of rotation speed. The harmonic current suppression at variable rotation speed is a challenging research topic. In order to suppress harmonic current in AMB whose frequencies are integer multiples of the rotation frequency of rotor and to maintain system stability, multiple phase-shift notch filters are proposed in this paper. The closed-loop stability is ensured by adjusting the phase at variable rotation speed. Experiments are carried out on vibration measurement table and magnetically suspended flywheel prototype to show the effectiveness of the proposed method.