Piezoelectric vibration energy harvesting using strain energy method

Abstract

Piezoelectric beams are the most common energy converters for mechanical-to-electrical energy. In this paper, an analytical method is introduced and developed for modeling piezoelectric vibration-based energy harvester, which is a strain energy method, and it is simple enough and straightforward than similar methods, such as finite element and FRFs approaches. Closed-form expressions have been extracted for the open-circuit natural frequencies, open-circuit voltage, generated current, and maximum output power which are important parameters of the energy harvesting system, therefore measurements don’t need the experimental setup to take. Piezoelectric layers are also investigated in both parallel and series connections which produce equal power at optimum resistive load but cause different voltage and current in the resistive load. The maximum output power occurs when the equivalent capacitive reactance of piezoelectric layers is equal to the resistive load; in addition, the optimum load resistance in series connection is 4 times larger than the parallel connection. Depending on the type of generator’s usage and its application, an appropriate decision regarding the parallel or series connection could be made. The maximum normalized power density in the fundamental natural frequency, at the optimum thickness and the optimum load resistance, was 18.717