Power Generation And Pivotal Technique Of Discal Energy Harvester

With the recent advances in microelectro-mechanical systems and wireless technology, the demand for portable electronics is growing rapidly in martial filed and civil industries. However, a traditional electrochemical battery can no longer meet the needs of advanced sensing technology due to its limited large volume, large weight, service life, difficulty in replacement and environmental pollution. Thus, the power of micro-electronics products is need to imminently consider. Much attention has been paid to scavenging energy from the ambient environment in recent years because it can supply the power micro-electronics products. The piezoelectric cantilever energy harvester has difficulties to work directly without some fractures in the high stress condition due to its less ability of the mechanical stability. It has been found that the circular metal-ceramic transducers have the capability to withhold dynamic high stresses. The calculated modal, structural analysis and output power of the typical metal-ceramic energy harvesters were investigated in detail.Cymbal harvester is a typical metal-ceramic transducer which is studied for scavenging vibration energy. Based on the force analysis and piezoelectric theory, a mathematical modal of the cymbal transducer was presented to calculate the output power of the energy harvester. The effects of structural parameters on the output voltage and resonant frequency of the cymbal transducer were analyzed by ANSYS. Some optimal methods which could increase the conversion efficiency were presented to decrease the circular stress of the cymbal transducer. The effects of the structural parameters of slots on the output voltage were also analyzed and an optimal method was confirmed. In order to study the coupling action between piezoelectric and electric circuit sides, a model of the piezoelectric structure and electric circuit was developed, and the effects of the vibrated frequency and resistive load on the output power were presented which can be useful to design the cymbal energy harvester.The drum energy harvester was studied due to the high effective piezoelectric charge coefficient. Based on the vibrated theory of the thin plate and piezoelectric theory, a modal was developed to calculate the resonant frequency. Power generation from the drum transducer was modeled by using the piezoelectric theory. The relationship between the structural parameters, output voltage and resonant frequency of the drum transducer were analyzed by ANSYS. The coupling action between piezoelectric and electric circuit sides of the drum energy harvester which can be useful for application was studied.A novel transducer which should withhold cyclic high stresses and have high effective piezoelectric charge coefficient was design due to the advantages of the cymbal and drum transducer. The effects of the structural parameters on the output voltage, displacement and resonant frequency were analyzed to confirm the reasonable structural parameters. A model of the piezoelectric structure and electric circuit of the cymbal-drum transducer was developed to analyze the effects of the vibrated frequency and resistive load on the output power.Integration of the previous studies, energy storage circuits were designed. And a reasonable technics which can decrease the errors among the transducers was selected to fabricate the transducer. The output power of the energy harvesters were measured by the experimental methods. The results show that the output power initially increases with the resistive load, whereas it will decrease when the resistive load is further increased. At each of these frequencies, it has an optimal load corresponding to the maximum output power density. It can be found that the results obtained from the theoretical modal are in very good agreement with those from experimental results. The results also show that the drum energy harvester has the highest power density which can reach 980 W/m3, however the drum transducer can't used directly in the high stresses condition. The cymbal-drum transducer has the high effective piezoelectric charge coefficient and can work directly in the high stresses condition. Compared with the cymbal and drum energy harvester, the cymbal-drum energy harvester is optimal.