<p> Piezoelectric materials have a unique characterization which can absorb energy from the environment and convert it to electrical energy. In this conducted research energy harvesting of the THin layer UNimorph DrivER (THUNDER) were investigated. THUNDER is a curved PZT which bring considerable benefits in compare of flat PZT such as better vibration absorption capacity and higher energy recovery efficiency. Also one of the most important characteristics of THUNDER is its low resonance frequency. Because the maximum power a harvester can achieve is at its resonance frequency. So it has application in low resonance frequency situations. In this work, general constitutive law for piezoelectric materials is reduced because it is assumed THUNDER is thin and modeled as a Euler-Bernoulli beam. To obtain mechanical-electrical coupling equations, Hamilton principle is used. Hamilton principle is using kinetic and potential energy and work due to the external force as its input. As a result, modals and natural frequency of THUNDER are obtained. Then based on boundary condition, natural frequency can be achieved. By using Rayleigh-Ritz approach and in-extensional assumption and assuming excitation is sinusoidal, discretize mechanical-electrical coupling equations can be written. For the experiment part, two modes energy harvesting circuit is used, the first one is full bridge rectifier in low-level excitation and steps down converter in high-level excitation. Also, resistor and battery are used as an external load. Because rectified voltage is equal battery voltage, so the model needs to be adjusted by putting a step-down converter in the circuit to adjust Voltage and get the maximum power from the model. In the case of the resistor as an external load, the maximum power will achieve near resonance frequency and also by increasing the amplitude of resistors, more power can be achieved by the circuit. Also, step down converter is used in two modes, continuous conduction mode(CCM) and Discontinuous conduction mode(DCM). Power harvesting in this two mode also compared.</p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:10243311 |
| Date | 18 February 2017 |
| Creators | Mahmoudiandehkordi, Soroush |
| Publisher | Southern Illinois University at Edwardsville |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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