Study on the Strain Effect of a Piezoelectric Energy Harvesting Module

Abstract

In order to investigate the relationships among strain, frequency, and output power, a novel piezoelectric energy harvesting module with controllable strain was designed. Conventional vibration module can control over strain through variation in tip mass, but it is also affected by vibration frequency. In the contrast, the designed controllable strain module allows more accurate strain control at various frequencies through adjustment of the displacement of the free end of the cantilever from 5 mm to 45 mm. Experimental results proved that both types of modules exhibit an increase in open circuit output voltage with strain. But output voltage was decreased when the piezoelectric ceramic broke at severe strain. In addition, it was confirmed that the proposed module design can keep the strain constant, which allows investigation into the relationship between frequency and output power. At constant strain, the matching impedance was found to be low at high frequency. Thus, as effect of strain to the piezoelectric energy harvesting module, the optimum conditions for harvesting maximum power are found to be high frequency and the largest strain do not degrade the piezoelectric plate.