Seminar Series - 2001-2002

Analytical Modeling of Piezoelectric Transformers and Resonators

Xuesong Zhang, M.S. Thesis Defense
Department of Engineering Mechanics
University of Nebraska - Lincoln
Advisor:  Dr. Jiashi Yang

Date: Monday, July 15, 2002
Time: 2:00 p.m.
Place: W183 Nebraska Hall


Piezoelectric transformers are a relatively new type of electromechanical devices. They have smaller sizes and higher efficiencies comparing to traditional electromagnetic transformers. So they meet the need of miniaturization of electronic equipment better. At present reported results on piezoelectric transformers are mostly experimental. The first part of this research gives a thorough analytical analysis of the classical Rosen piezoelectric transformer using the linear theory of piezoelectricity. Analytical results fundamental to the understanding and design of piezoelectric transformers are obtained. A similar analysis is also performed for a transformer working with a shear vibration mode. The feasibility of transmitting electric energy through an elastic wall using piezoelectric transducers is examined using the same theory.

Piezoelectric resonators are the key components in time-keeping and telecommunication equipments. Recently applications of piezoelectric resonators as acoustic wave sensors are also growing. Frequency stability of piezoelectric resonators is the resonant frequency shift caused by environmental changes, such as acceleration, temperature or pressure changes. The effect of constant acceleration on resonant frequencies has been studied systematically, but little is known when the acceleration is time dependant. Based on the theory of small fields superposed on finite biasing fields in an electroelastic body, the effect of dynamic biasing fields on resonant frequencies is studied in the second part of this research. Pressure and temperature sensors based on frequency shifts in resonators are also studied.


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