Harnessing energy via piezoelectricity vibration

Abstract

In an effort to eliminate the replacement of the batteries of electronic devices that real difficult or impractical to service once deployed, harvesting energy from mechanical vibrations or impacts using piezoelectric materials has been researched over the last several decades. However, a majority of these applications have very low input frequencies. This represents a challenge for the researchers to optimize the energy output of piezoelectric energy harvesters, due to the relatively high elastic moduli of piezoelectric materials used to date. This project reviews the current state of research on piezoelectric energy harvesting devices at low frequency (<100 Hz) applications using vibrating motor and the methods that have been develop to improve the power outputs of the piezoelectric energy harvesters. This project study is divided into two main parts which are simulation from the forced vibration data and laboratory experiment on vibrating motor. The simulation results shows that as the acceleration magnitude increases, the average direct voltage also increases from 4.5 mV to 8.1mV and the average power output that could be harnessed also increased from 22.5 μW to 40.5 μW. The experimental work energy harvesting structures focused on a bimorph piezoelectric rectangular plate (two faced PZT layer bonded to a brass substrate) that would be driven by ambient vibration source (motor). Multiple tip mass value on the effect of power generated was investigated in this project. It is shown that motor speed at 100 rpm has the highest power generated both with (1667.21 μW) and without (10.15 μW) the addition of tip mass. Besides, it is also observed as the motor speed increased from 900 rpm to 1000 rpm, lower tip mass value required to optimize the power generated. 20g of tip mass value is required to generate 218.21 μW at motor speed 900 rpm, 10g of tip mass value is required to generate 626.29 μW at motor speed 1200 rpm These power output is sufficient for low powered electronics which can be used in variety of applications as indicated in the literatures reviewed.