Optimization of the Energy Conversion Efficiency by Bending Deflection Piezoelectric Cantilever Beams

Abstract

In the field of piezoelectric energy harvesting, a cantilever is widely used in a piezoelectric energy harvester (PEH) because it easily deforms under various forces and, generally, the output of the cantilever increases proportionally with the deformation. Naturally, many previous studies focused on how to obtain a higher PEH output. However, the power of the input source is limited, so the efficiency of the PEH must be maximized. In this study, based on the amount of input energy, the existence of an optimal efficiency of energy conversion in the PEH was researched. A plate-type PEH was first installed as the cantilever, and various masses were suspended from the free end of the PEH by using a thread. Next, the thread was cut while the PEH was in a bending state. Immediately, the PEH began vibrating with the input energy being the potential energy of the bent PEH, and the output was obtained. A maximum efficiency of 15.58% was determined in three ways: via the output electrical energy (0.46 mJ), the input potential energy (2.94 mJ), and the deflection value (at a free end position of 3.75 mm). Finally, the existence of the optimal efficiency based on the amount of input energy was found in this PEH.