| With the development of techology, many kinds of portable power devices have been new hot research topic with the purpose of replacing or charging batteries in some special application fields. The power generation units which are made of different kinds of principles have their own characteristics and application area, and piezoelectric transform is characterized by its simple structure, no electromagnetic interference, easy to realize the miniaturization of structure and manufacture, thus it is suitable for fabrication of various kinds of transducers. However, the problems are that (1) most of the piezoelectric transducers are made of PZT materials, which are harmful to environment and human beings during the process of preparation and abandonment, thus it is urgent to exploit lead free piezoelectric materials with excellent quality; (2) the modeling theory doesn't posess universality, developing effective theoretical model is useful to analyze the devices directly; (3) the output voltage and power density of the device is not large, therefore the devices need to be improved.According to the above problems, this dissertation anylized the types of the piezoelectric materials, the structures of the devices and vibration mode, finally, proposed the research content of piezoelectric vibration energy harvester.Lead free (Ba0.95Ca0.05)(Ti0.90Sn0.10)O3+xmolCuO (BCT-BST-xCu) ceramics were prepared by conventional solid-state reaction technique, the influencce of sintering temperature and CuO content on the phase constitution, ferroelectricity, piezoelectricity and dielectricity were discussed. The d33, ?, Pr and Ec values of the corresponding ceramic samples that were sintered at 1350? with the CuO content of 2%mol are 570pC/N,25000, 9.63?C/cm2 and 0.7kV/cm.The dissertation analysed structural design, compared with other support modes, the cantilever transducer with a piezoelectric bimorph in series is not only easy to adjust the resonant frequency but also suitable for low frequency vibration. After establishing the mode of energy harvester, an universal non-dimensionalized lumped-parameter model was set to anlyze the energy harvester theoretically and it discussed the influence of thickness of lead free ceramic, tip mass, resonant frequency, load impedance and acceleration on output voltage and power density.This dissertation built a testing system for piezoelectric energy harvesting based on the above research, and it was found that the resonant frequency can be adjusted by the tip mass, the output power density can reach 2.83mW/cm3 when load impedance matched the internal resistance of the ceramics which thickness is 0.4mm. |
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