Performance Study And Numerical Analysis On Vibration Energy Harvester

With the evolution of low power electronics, harvesting the structural vibration energy, which isclean, ubiquitous and renewable, has gained extensive attentions from worldwide researchers in therecent decade for its high potentials for applications in areas of wireless sensor networks (WSNs),implanted electronics, etc., to replenish or even replace the traditional power supply such as batteries.A large number of vibration energy harvesters (VEH) using the piezoelectric effect have beenproposed and developed.To increase the power harvesting capability of an internal impact type vibration energy harvester(VEH), we have developed a novel hybrid VEH integrating both piezoelectric and electromagnetic(EM) modules for energy conversion. The proposed VEH transforms a low frequency base vibrationinto the vibration of the tip of a cantilever beam, which is used to cause energy conversion by thepiezoelectric effect and electromagnetic induction. A prototype is designed, fabricated and tested; theoptimum load resistances are determined experimentally, and the power output performance and thetotal power density of the proposed VEH have been experimentally characterized with respect to theexcitation amplitude and frequency.Numerical analysis of a vibration energy harvester system is very helpful to the optimization ofthe system. But the research on this topic is very little. In this paper, the PSPICE based simulationmethod is used to determine the optimal capacitance of energy storage capacitor of a vibration energyharvester with multiple piezoelectric components to obtain a maximum energy storage power, and toinvestigate the effect of the equivalent circuit parameters of piezoelectric components on the storedenergy.In this paper, we also have proposed a kind of thickness non-uniform beams with three differenttopologies, i.e., beam with rectangular grooves (BRG), beam with arc grooves (BAG) and beam withtriangular grooves (BTG), and applied the beams to piezoelectric impact vibration energy harvesting.Each non-uniform beam has three evenly spaced grooves of identical size, and three identicalrectangular piezoelectric patches bonded on it. Each piezoelectric patch has the same central positionas its corresponding groove, and the three piezoelectric patches are connected in parallel electrically,which comprises the energy harvesting unit. Energy harvesting characteristics including voltages andoutput power are experimentally tested. Comparisons were made both experimentally and numerically. It is found that the grooved beams have better energy harvesting performance than conventionaluniform beam and the beam with rectangular grooves owns the best energy scavenging capability.