Research On A Hybrid Piezoelectric-electromagnetic Vibration-powered Device

Wireless sensors are becoming increasingly popular because of their small size, low power consumption and ability to be employed in inaccessible and hostile environments, such as condition monitoring of bridges, health care, etc. Traditional power storages such as batteries have a limited lifetime, must be replaced periodically, bring the material waste, environmental pollution and other issues. Energy harvester is a possible alternative of batteries that converts the existing environmental vibration energy into usable electric energy.The most commonly pursued energy harvesting mechanisms are electromagnetic and piezoelectric. In this work, a hybrid piezoelectric-electromagnetic vibration-powered generator(HPVG) is presented, and the power output level of the HPVG is greatly improved. A theoretical power output model is presented and verified by the Finite Element Simulation method and the experimental method.Firstly, this paper introduces the theory of electromagnetic and piezoelectric energy harvesting technology. In theory, we made an analysis of the electromagnetic generation principle, the finite element analysis, induced electromotive force and the axial magnetic force between two magnetic rings. Besides we made an analysis of the basic piezoelectric materials, and made a deep analysis of the piezoelectric cantilever beam. Using the finite element method analysis of cantilever beam, and a calculation is made on its natural frequency.Then the mathematical model of the HPVG was built. And we made an analysis of the power output through the traditional spring-mass-damper system. Finite Element Analysis(FEA) was applied to the new generator in this paper, the resonant frequency, output voltage and power output is shown in this paper.Finally, a prototype of the hybrid piezoelectric-electromagnetic power generator was manufactured. Then the power generating performance of the hybrid device was tested. The experimental results agree with those of the theoretical analysis and finite element simulation very well. It shows that there exists a coupling effect between the two different mechanisms. The study also proves that even though the power output from both of the two mechanisms of the hybrid technique, respectively, a increase in the total power output can be obtained by adjusting parameters such as external load resistance.