Impact of Series and Parallel Connection of Macro Fiber Composite Patches in Piezoelectric Harvester on Energy Storage

Dariusz Grzybek,Piotr Micek

doi:10.3390/en14092379

Abstract

A beam containing a piezoelectric layer or layers is used for piezoelectric harvesting from various processes. The structure of the beam is made by gluing the piezoelectric material on one side (unimorph) or both sides (bimorph) of a carrying substrate. Two piezoelectric layers, glued on both sides of the substrate, may be electrically parallel or series connected. This paper presents an experimental analysis of the impact of parallel and series connections of two Macro Fiber Composite (MFC) MFC patches in a bimorph on the charging of a capacitor. In experiments, the effective charging process of the capacitor was obtained both for parallel and series connection of two MFC patches. The bimorph with a parallel connection generated a larger capacitor charging power than the bimorph with a series connection in the range of voltage across the capacitor from 1 to 18 V. However, the bimorph with a series connection was more effective than a parallel connection for voltage across the charged capacitor from 18 to 20 V. The maximum capacitor charging power generated by the bimorph, in which two MFC patches were parallel connected, was 1.8 times larger than that generated by the bimorph with a series connection and was 3.3 times larger than that generated by a unimorph with one MFC patch. The impact of level of voltage across the capacitor on its discharging process has a significant meaning for the ratio of maximum power between bimorphs and between the bimorph and unimorph.

Highlights

Piezoelectric energy harvesting from processes in which mechanical energy may be wasted has recently been the subject of intensive study in the scientific field
The maximum capacitor charging power generated by the bimorph, in which two Macro Fiber Composite (MFC) patches were parallel connected, was 1.8 times larger than that generated by the bimorph with a series connection and was 3.3 times larger than that generated by a unimorph with one MFC patch
The bimorph with a series connection was more effective in the capacitor charging process than in parallel connection for the highest voltage across a charged capacitor

Summary

Introduction

Piezoelectric energy harvesting from processes in which mechanical energy may be wasted has recently been the subject of intensive study in the scientific field. Piezoelectric materials are used for energy harvesting from, e.g., building vibrations, the motion of machine elements, wind energy, ocean waves, acoustic energy and biomechanical reactions. Mechanical energy is converted into electric energy by the use of a device, called a harvester, in which piezoelectric material is deformed by its mechanical structure. The beam, which is constructed from a carrying substrate and a piezoelectric material, is applied for energy harvesting from various processes: mechanical vibration [1,2], rotational motion [3,4] and wind energy [5,6]. Mechanical energy is converted into electric energy in a piezoelectric material, which is squeezed or stretched during beam bending. Composites have lower efficiency in energy conversion than piezoelectric ceramics, but are more resistant than monolithic ceramic to destruction due to deformations [8]

Results

Discussion

Conclusion