Characteristics of piezoelectric energy harvesting circuits and storage devices.

• Other Authors: Guan, Mingjie.
• Format: Others
• Language: English; Chinese
• Published: 2006
• Subjects: Integrated circuits; Piezoelectric devices; Solar collectors
• Online Access: http://library.cuhk.edu.hk/record=b6074303; http://repository.lib.cuhk.edu.hk/en/item/cuhk-343932

Based on constitutive equations of piezoelectricity and two-port modeling method, the models of piezoelectric materials are investigated. The equivalent circuit models of the piezoelectric element in the energy harvesting system are explored. It is found that there exists an optimal external impedance that gives the maximum output power. Experiments are conducted to verify the optimal impedance theory. === The energy storage devices in the piezoelectric energy harvesting system are analyzed. The charge/discharge efficiencies of the energy storage devices are mainly considered. Based on the analysis of the electric characteristics of the energy storage devices, we find the leakage resistances of the energy storage devices are the dominant factor that influences the charge/discharge efficiency in the piezoelectric energy harvesting system. A quick test method is proposed to experimentally study the charge/discharge efficiencies of the energy storage devices. The experimental results verify our findings. Adaptability, lifetime, and protection circuit of the energy storage devices are also discussed. It can be concluded that the supercapacitors are suitable and more attractive than the rechargeable batteries to store the energy in the piezoelectric energy harvesting system. === Two schemes of piezoelectric energy harvesting circuits are analyzed: one-stage and two-stage energy harvesting schemes. The efficiency of the two-stage harvesting scheme is found to be related to several factors including the energy storage device voltage. Analysis and experiments using one-stage energy harvesting circuit to harvest a varying excitation source are explored. The results show that one-stage energy harvesting scheme can achieve higher efficiency than the two-stage scheme towards a range of energy storage voltages. === Using piezoelectric elements to harvest energy from ambient vibration has been of great interest recently. Because the power harvested from the piezoelectric elements is relatively low, energy storage devices are needed to accumulate the energy for intermittent use and energy harvesting circuits are applied to transfer the electrical energy from the sources to the storage devices. Therefore, a piezoelectric energy harvesting system can be basically divided into three parts: the energy source, the energy harvesting circuit, and the energy storage device. These three parts are explored in this thesis. === Guan Mingjie. === "September 2006." === Adviser: Wei-Hsin Liao. === Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1822. === Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. === Includes bibliographical references (p. 123-128). === Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. === Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. === Abstracts in English and Chinese. === School code: 1307.