Energy harvesting using piezoelectric materials and high voltage scavenging circuitry

Piezoelectric transducers are increasingly being used to harvest energy from environmental vibrations in order to power remote sensors or to charge batteries that power the sensors. In this paper, two modifications have been analyzed and tested to increase the harvested electrical power from a vibrating piezoelectric material. First, the voltage inversion method, which has recently been used in piezoelectric-based energy harvesting, and that shapes the voltage to be in phase with current in order to increase the harvested power is reviewed. By injecting additional current, a new voltage inversion scheme, referred as voltage compensation scheme, is introduced. This new scheme provides more than 14% increase in harvesting power over the parallel inversion method (parallel SSHI) alone and more than 50% in the case of series inversion method (series SSHI) alone. Second, the tapered cantilever beams were shown to be more effective in generating a uniform strain profile over rectangular and trapezoidal beams if they are precisely shaped. Using this modification, it is shown that a 300% increase in harvested power over available methods in the literature is obtainable.