Design And Research On Micromniature Piezoelectric Wind Energy Harvesters

Microminiature piezoelectric wind energy harvesting technology is a new direction in the field of micro energy. The piezoelectric wind energy harvester provides a promising solution to the power supply for small low-power electronic devices, and has great application potential and research value. For the present harvesters, there are still some problems to be solved such as the complex structure, low output voltage, small power density, low efficiency of the energy harvesting and so on.To address these problems, based on piezoelectric principle and wind-induced vibration mechanism, this dissertation proposes two novel two-degree-of-freedom(2-DOF) microminiature piezoelectric wind energy harvesters(i.e. the galloping-wake harvester and galloping-vortex-induced via structure coupling harvester) in the wake of three single-degree-of-freedom(SDOF) wind energy harvesters: the wake vibration harvester, vortex-induced vibration harvester and galloping harvester. The two 2-DOF harvesters make full use of the drafting of the Karman vortex street and can be used in low wind speed environment, which also have a large amount of advantages such as simple and compact structure, easy to be implement and so on. Besides, the theoretical model of the two 2-DOF harvesters are established, simulated and analyzed.Then, the experimental platform is built, five different kinds of prototype(the three SDOF and two 2-DOF harvesters) are made and tested, respectively. Finally, a comparative study on the influence of the wind speed, mass area, and inner beam length on the output voltage of the five prototypes are made. The results show that the output voltage of the vortex-induced vibration harvester is higher than that of the wake vibration harvester of the SDOF harvesters; the output voltage of the tow 2-DOF harvesters are improved significantly than that of the three SDOF harvesters; the output voltage of the galloping-vortex-induced via structure coupling harvester is higher than the galloping-wake vibration harvester of the two 2-DOF harvesters, therefore, the performance of the galloping-vortex-induced via structure coupling harvester is the best of the five harvesters. In addition, the results also indicate that the overall output voltage of the tow 2-DOF harvesters can be further increased by adjusting the inner beam length and the mass area when the outer beam length is fixed.