Autonomous wideband mechanical energy harvester

The aim of this work is to demonstrate, by theory and experiment, the feasibility of a mechanical energy harvester able to operate with a high efficiency over a wide vibration frequency band. Herein this work we propose a new method for adjusting the resonant frequency of a mechanical harvester, based on piezoelectric material. The idea is to use the dependence that exists between piezoelectric material stiffness and the electric load coupled with. Hence, piezoelectric stiffness can be controlled by controlling the electric load. We present the model of our system and then the main experimental results that validate the principle for resonant frequency tuning. Finally, we present the low power consumption electronic developed to automatically adjust the vibration frequency in order to maximize, in real time, the output power.