Experimental Study of Optimum Piezoelectric Energy Harvester Circuit under Various Excitations

Abstract

Energy harvesting from environment vibrations by piezoelectric cantilevers is an attractive field for investigation because of piezoelectric material's inherent mechanical-electrical properties. In this paper, electrical and mechanical characteristics of piezoelectric cantilever are investigated for optimum energy harvesting, experimentally, which this cantilever is excited under harmonic, random and impulse excitations. Consequently, piezoelectric energy harvester is simulated as an equivalent electrical circuit. For this purpose, effect of external load resistance and excitation frequency on the output voltage is studied under harmonic excitation firstly. Furthermore, the effect of load resistances on natural frequency of piezoelectric cantilever is investigated while piezoelectric beam is under random excitation. Furthermore, variation of equivalent viscose damping ratio (ζ) of piezoelectric cantilever due to changes in external load resistance is studied by applying impulse excitation. Finally, the electrical properties of piezoelectric cantilever such as internal load resistance and capacity are acquired experimentally and the effect of load resistance on optimal energy harvesting is considered. Verifying the experimental harmonic and random excitations results in open circuit mode are conducted by finite element modeling in ABAQUS software.