| Summary: | 碩士 === 國立臺灣大學 === 應用力學研究所 === 96 === This thesis studies energy harvesting using piezoelectric elements as energy transducer materials. The ambient vibration energy is transmitted into electrical energy via electromechanical coupling. The harvested energy is further stored by choosing suitable energy harvesting circuits. Here we propose an appropriate physical model accounting for the effect of electronic interfaces on the harvested power output.
We analyze the behavior of energy harvesting system for two different electronic circuits. One is the standard interface and the other is the relatively new interface called SSHI (synchronized switch harvesting on inductor). In each circuit, two different magnitudes of electromechanical coupling piezoelectric materials are adopted and studied. In the case of standard interface, it is found that there is only a single peak for optimal power when the coupling effect is in the medium range. On the other hand, there is a pair of optimal power for the case of strongly coupled electromechanical system. Further, it is found that there is always a single peak of power in the case of SSHI system. In this case, the output power drops significantly when the applied frequency deviates from the resonance, in particular, in the case of strongly coupled materials. Therefore, the desired output power for the SSHI system is in the case of mid-range of electromechanical coupling.
The effect of diode loss is also studied here via experiment. This effect is significant when the applied frequency is close to the short circuit resonance in both cases of standard and SSHI interfaces. One approach to overcome it is to increase the magnitude of applied acceleration. Finally, the piezoelectric elements in series and parallel forms are proposed to enhance the output power.
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