Abstract
We experimentally validate the properties of piezoelectric energy harvester connecting to SSHI nonlinear circuit and derive an equation of motion for the practical piezoelectric energy harvester, considering nonlinear stress. The previous study did not discuss how the nonlinear stress affects the electromechanical properties for the harvester connecting to the SSHI circuit, while the SSHI circuit is likely to increase piezoelectric damping force. This study uses cantilever beam harvesting device, and parallel bimorph piezoelectric elements. Firstly, we obtained the equation of motion for the harvester based on the nonlinear piezoelectric equation proposed previously. Secondly, we investigated the impedance matching and frequency response experimentally. In the impedance matching, the rate of increase in the output power for SSHI circuit, compared to the standard circuit, decreased as the acceleration level increases, and the peak of the output power shifted to low electrical resistance. In the frequency response, the experimental result showed that the resonance frequency decreased as the acceleration increased. The derived nonlinear equation predicted these phenomena, therefore these results are most likely due to the effects of nonlinear stress.
