Electromechanical characteristics of piezoelectric vibration energy harvester with 2-degree-of-freedom system

Abstract

Enhancing the output power at small input acceleration is a major concern for enabling practical application of vibration energy harvesters. In this study, a two-degree of freedom system (2-DOF) was employed to solve this issue. The numerical calculations using the lumped parameter model of the piezoelectric vibration energy harvesters (pVEHs) with 2-DOF indicate that the harvesters show two resonance peak and an increase in the output power of several ten times compared with the harvester with a single degree of freedom. Based on calculations, the prototype of pVEH with 2-DOF was fabricated using a micro-machined pVEH and a metal cantilever. The output power of the harvester is 3.4 μW at 0.1 Grms, which is 17 times higher than that of the micro-electro-mechanical system-pVEH. Moreover, the resonance frequency on the pVEH with 2-DOF is easily adjusted because of the coupled vibration of the two masses.