Frequency-adaptive autobalancing control for magnetically suspended rotor with imprecise rotational speed

Unbalance of the magnetically suspended rotor (MSR) causes synchronous vibration. In order to eliminate synchronous vibration and compel the rotor to rotate about its inertial axis under the circumstances of imprecise rotational speed, a closed-loop designed adaptive notch filter (ANF) is proposed, which can estimate the rotational speed and extract synchronous component from the rotor displacement simultaneously. Compared with conventional open-loop designed ANF, it is designed according to closed-loop transfer function of the magnetic bearing system and can preserve system stability by adjusting its parameters. The closed-loop designed ANF and a feedforward compensator constitute a frequency-adaptive autobalancing control scheme. Through simulation, the performance and effectiveness of the designed autobalancing control is demonstrated. In experiments, this method reduces synchronous vibration force of a MSR from 22 N to 1.8 N.