| Summary: | 碩士 === 國立臺灣大學 === 應用力學研究所 === 104 === This thesis discusses some problems in piezoelectric energy harvesting based on certain finite element (FE) models. It consists of two parts. The first part uses the FE simulation for performance evaluation of different methods used for deriving the equivalent parameters of a piezoelectric energy harvesting system. The second part is to perform the experiment for validating the FE model of a rectified piezoelectric energy harvesting system.
Specifically, there are three methods for finding the equivalent system parameters. The first one is based on the Hamiltonian energy principle and the Rayleigh-Ritz approximation. While all the parameters can be derived analytically, they can only be evaluated if the material properties of a device are known in advanced. In addition, the modal function used in Rayleigh-Ritz approximation may not be available for the case of irregular geometry of piezoelectric elements. The second one is based on the finite element simulation of a piezoelectric system together with the prescribed equivalent mass and force parameters derived from the energy formulation. This approach shows good accuracy, but it needs some parameters from the energy approach. Finally, the third approach is based on the equivalent circuit model. It shows very good accuracy in various magnitudes of electromechanical couplings. However, only the electric parameters can be revealed from this approach.
The second part is to develop an experiment setting for validating the FE model of a rectified piezoelectric energy harvesting system proposed by Prof. Shu’s research group. A piezoelectric cantilevered bimorph is used and the interface circuits include the AC circuit, the standard rectified interface and the parallel synchronized switch harvesting on inductor (P-SSHI) circuit. The experimental results agree quite well with the proposed finite element simulations.
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