On the Efficiency of Electric Power Generation With Piezoelectric Ceramic

This paper analyzes the efficiency of piezoelectric ceramic for purposes of electric power generation. An analytical model is presented which suggests that the primary problem of using PZT for electric power generation is that most energy is stored in the ceramic and returned to the mechanical port. The efficiency as a function of force input frequency and resistive load are derived based upon a linearized model of a commercially available PZT stack. The analysis yields counterintuitive results in that maximum efficiency occurs in a low frequency region, several orders of magnitude below the structural resonance of the stack. The analytical results are followed by presentation of experimental data that substantiate the model. The model is then utilized to show that, due to hysteresis in the ceramic, the efficiency of energy transfer is dependent on the amplitude of force input, and that greatest efficiencies can be achieved with maximum input forces.