Effects of a series capacitor on the energy consumption in piezoelectric transducers at high vibration amplitude level

In this paper, a driving method for low-loss generation in piezoelectric tr ansducers at a high vibration amplitude level is presented. First, we analy ze the power consumption of several loss mechanisms of piezoelectric transd ucers using an electrical equivalent circuit model. In this model, loss due to piezoelectric effect is explicitly represented by a series resistor, an d pure dielectric loss is separately denoted by a parallel resistor. Mechan ical loss is represented by a series resistor in the mechanical arm. The re ason for the high efficiency at the anti resonance frequency is explained b y this analysis. Next, the effect of an external series capacitor is discus sed by comparing the experiment with the calculation, based on the equivale nt circuit model for the high vibration amplitude level. By using the exter nal series capacitor, the loss generated at the high vibration amplitude wa s significantly reduced without a large increase in electrical impedance.