Ferroelectrics, 450:99–106, 2013 Copyright © Taylor & Francis Group, LLC ISSN: 0015-0193 print / 1563-5112 online DOI: 10.1080/00150193.2013.838502 Finite Element Modeling of Ring-Shaped Piezoelectric Transformer CHUMPOL SUPATUTKUL 1,∗ AND YONGYUT LAOSIRITAWORN 1,2 1 Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand 2 Thailand Center of Excellence in Physics (ThEP), Commission on Higher Education, Bangkok 10400, Thailand In this work, we developed a finite element package to investigate the dependence of electromechanical coupling coefficient on ring-shaped piezoelectric transformer pa- rameters, and proposed how to design the transformer in achieving optimum efficiency using the ceramic PZT-5H as an application. The ring transformer firstly used full driven electrode to observe piezoelectric vibration characteristic with varying the ring dimensional (structural) parameters. Then, with the optimized ring parameters, elec- trode layout was designed in accordance to the distribution of electrical potential within the ring transformer, where both alternating and non-alternating electrode layouts were considered. From the calculation, results showed that the piezoelectric vibration char- acteristic strongly depends on the ring-shaped transformer dimension. Specifically, with increasing piezoelectric ceramic thickness and the width between inner- and outer-ring- radius, the resonance frequencies of the transformer decrease. On the other hand, in terms of the electrode layouts, the alternating electrode was a better choice in obtaining desired resonance frequency mode, as it provides larger electromechanical coupling co- efficient than the non-alternating electrode. These results are in agreement with previous experimental investigation, where applicable. Keywords Electrode layout; finite element analysis; ring-shaped piezoelectric transformer 1. Introduction Piezoelectric transformer is a device that transfers energy among different electrical circuits via electromechanical coupling, i.e. the so called piezoelectric effect. This piezoelectric transformer functions by transferring electrical energy from the primary- to secondary- electrode via mechanical vibration. In addition, as nowadays the electronic devices become reducing in size (but equipped with more complex functions), the compact transformer with high efficiency in energy transferring is in great demand. Therefore, as without any magnetic cores and wires like in conventional transformer, the piezoelectric transformer can be fit into this requirement. In addition, the piezoelectric transformer is easy to miniaturize and has many benefits upon the conventional such as no electromagnetic interference, inflammable and high efficiency. Received December 11, 2012; in final form March 15, 2013. ∗ Corresponding author. E-mail: supatutkul@gmail.com 99