Stability Compensation for Piezoelectric Shunt Damping with a LR Circuit Using Digital Virtual Impedance

Piezoelectric shunt damping is a unique technique, which utilizes a piezoelectric element as both an actuator and a sensor. In this paper, we consider a virtual impedance circuit with a DSP. The analog lowpass filters are necessary for anti-aliasing and smoothing in the use of the digital virtual impedence, however the system becomes unstable due to the filters. Therefore we conduct stability analysis with the open-loop transfer function and propose a simple method for stabilizing the system using a digital band-pass filter. Experimental results show the effectiveness of the proposed method for the shunt damping with the digital virtual impedence.