İnce bir plaka ve piezoelektrik yamadan oluşan enerji üretecinin sonlu elemanlar modelinin ve AC-DC dönüşümü içeren eşdeğer devre modelinin oluşturulması

Research on vibration based energy harvesting has received great interest over the last two decades with motivation to provide continuous power to small electronic devices and eliminate the need of battery replacement and disposal. Ambient vibrations available in the environment of such devices can be converted to electric energy through piezoelectric transduction mechanisms. A typical piezoelectric energy harvester application is attachment of a cantilever beam with piezoceramic layers to a vibrating host structure. Energy harvesting circuits are connected to piezoceramic layers to convert the AC output of the harvesters into a stable DC output to charge storage components. Cantilever harvesters have been widely studied in the literature. As an alternative to beam harvesters, piezoelectric patches can be easily integrated to thin plates to extract vibrational energy of their host structure and convert it into electrical energy. This implementation can be convenient especially for thin structures employed in aerospace, automotive, and marine applications to enable compact and broadband energy harvesting. Integrating piezo-patch energy harvesters to such host plates eliminates the mass loading and volumetric occupancy of base-excited cantilever design. Relatively limited literature has focused on energy harvesting for those two-dimensional structures. In this thesis, first, a coupled electroelastic FE model of a patch based piezoelectric energy harvester integrated to a thin plate is generated. Then, a multi-mode equivalent circuit model of the piezo-patch energy harvester is developed using finite-element model of the harvester by accounting for two-way coupling. Multi-mode circuit representation of the harvester is connected to linear and nonlinear circuit elements using the SPICE software. Simulation results are validated for the standard AC-AC and AC-DC configurations. For the AC input – AC output problem, voltage frequency response functions are calculated for various resistive loads, and they show excellent agreement with modal analysis-based analytical closed-form solution and with the finite-element model. For the AC input – DC output case, a full-wave rectifier and a smoothing capacitor are connected to the harvester circuit for conversion of the AC voltage to stable DC voltage. Finally, FE modeling technique for the AC input-AC output problem is also demonstrated on a case study which involved harvesting on a vibrating panel of a heavy duty truck cabin. The vibration response of the panel as well as the voltage output of the harvester patch under the real operating conditions is simulated using the forces obtained from experimental measurements on the vehicle. The electrical power generation of the harvester patch is predicted for a wide range of resistive loads. Electrical power outputs are then presented for short-circuit and open-circuit conditions. The numerical results show that the use of a harvester patch attached on a panel of a heavy duty vehicle generates reasonably good electrical power outputs.