A Low Frequency Vibration Control by Synchronized Switching on Negative Capacitance and Voltage Sources

Synchronized switch damping (SSD) techniques have recently been developed, as an alternative to active vibration control techniques, to address the problem of structure vibration control. In these techniques, a piezoelectric patch is bonded on the vibrating structure and shunted by a network of electrical elements. During the structure motion, the piezoelectric patch is connected and disconnected from the shunt circuit, according to the displacement extremum, through switching action controlled by a digital signal processing system. Thus the voltage in the piezoelectric patch is enhanced and time shifted in the time domain from the displacement of the vibrating structure. This voltage when shunted through electrical circuit results in increased energy dissipation with enhanced damping effect. This paper proposes to further increase the dissipated energy through a new technique called the synchronized switch damping on negative capacitance and voltage sources (SSDNCV). The idea is to further increase the value of voltage in the piezoelectric patch though the use of negative capacitance and two extra voltage sources in the shunt circuit. First theoretical expressions are derived for SSDNCV method to determine the maximum energy dissipated from the shunt circuit and the corresponding maximum damping. The effectiveness of SSDNCV method, as compared to the previous SSD methods, is then demonstrated in the first resonance mode control of a cantilever beam containing piezoelectric patch. The SSDNCV control reduced the vibration amplitude by 82 % as compared to 63 % and 29 % obtained from SSDNCI and SSDV controls respectively.