Semi-active vibration control by state-switched piezoelectric shunt circuit

The piezoelectric state-switched shunt circuit technique is an emerged semi-active vibration control approach. In this approach, the two poles of the bonded piezoelectric transducer are switched from the open state to short state, which leads to two kinds of vibration suppression effects: variable equivalent stiffness and energy dissipation. A novel piezoelectric state-switched shunt circuit is proposed based on the piezoelectric effects. The state-switch is closed when the induced electric charge on the piezoelectric transducer reaches its maximum, and then the positive and negative charge are neutralized. In this process, the dissipated mechanical energy is composed of two parts. One part is the damping of higher mode vibration of the structure which is induced by variable stiffness effect, and this part is neglectable for the amount of the stiffness variation is very small. The other is the electric energy which is dissipated as joule heat in the circuit so as to suppress the structure vibration. The AC/DC (alternating current/direct current) rectifier and the MOSFET (metal oxide semiconductor field effect transistor) are used in the shunt circuit to control the alternating current. The maximum/minimum voltage detector is designed based on Simulink/dSPACE system which can generate the pulse signal to open the switch at the right time adaptively. The experiment is carried out to suppress the harmonic response of a cantilever beam. The vibration amplitude is reduced by a rate of 55% after the control on. These vibration control results show the feasibility and the effectiveness of the state switched shunt circuit technique. Moreover, the effect of the pulse width is also studied in the experiments. It shows that the optimal pulse width is ten percent of the vibration period of the structure.