A novel method for shaft torsional oscillation suppression in servo systems

Torsional oscillations have been widely existed in load combined ac servo systems. Torsional oscillation could be a fatal factor that bound speed loop bandwidth, and exacerbate system dynamic response. This paper presents a method to design a PI controller for the speed loop of a one-mass system and determines the reason of the torsional oscillation of a two-mass system based on the frequency characteristics. The method is schemed to identify the resonant frequency of two-mass system and notch filter is proposed to effectively compensate the torsional vibration. Simulation results confirm that this method, if properly tuned, is an effective technique to identify the resonant frequency and reduce the torsional oscillation.