@article{9541, abstract = {{Piezoelectric transformers are increasingly getting popular in the electrical devices owing to several advantages such as small size, high efficiency, no electromagnetic noise and non-flammable. In addition to the conventional applications such as ballast for back light inverter in notebook computers, camera flash, and fuel ignition several new applications have emerged such as AC/DC converter, battery charger and automobile lighting. These new applications demand high power density and wide range of voltage gain. Currently, the transformer power density is limited to $40 W/cm{^3}$ obtained at low voltage gain. The purpose of this study was to investigate a transformer design that has the potential of providing higher power density and wider range of voltage gain. The new transformer design utilizes radial mode both at the input and output port and has the unidirectional polarization in the ceramics. This design was found to provide 30 W power with an efficiency of 98\% and 30 $\,^{\circ}$C temperature rise from the room temperature. An electro-mechanical equivalent circuit model was developed to describe the characteristics of the piezoelectric transformer. The model was found to successfully predict the characteristics of the transformer. Excellent matching was found between the computed and experimental results. The results of this study will allow to deterministically design unipoled piezoelectric transformers with specified performance. It is expected that in near future the unipoled transformer will gain significant importance in various electrical components.}}, author = {{Hemsel, Tobias and Priya, S}}, issn = {{0041-624X}}, journal = {{Ultrasonics}}, keywords = {{Piezoelectric transformers}}, pages = {{e741 -- e745}}, title = {{{Model based analysis of piezoelectric transformers}}}, doi = {{10.1016/j.ultras.2006.05.086}}, volume = {{44, Supplement}}, year = {{2006}}, } @inproceedings{8926, abstract = {{Piezoelectric transformers are well known since the publication of some patent applications at the end of the 1950s. But until today their only business use lies in the field of backlighting systems for LCDs. Due to key features as light-weight, flatness, high step-up at low volume and high efficiency piezoelectric transformers should be usable in a much broader range of applications. This contribution returns to mind their operating principle, shows how to model and to develop such devices as well as give some aspects for development trends that will lead to further applications.}}, author = {{Hemsel, Tobias and Littmann, Walter and Wallaschek, Jörg}}, booktitle = {{Ultrasonics Symposium, 2002. Proceedings. 2002 IEEE}}, issn = {{1051-0117}}, keywords = {{piezoelectric devices, reviews, transformers, backlighting systems, flatness, high efficiency piezoelectric transformers, high step-up, light-weight, low volume, operating principle, piezoelectric transformers, Circuits, Costs, Electromagnetic devices, Electromagnetic fields, Mechanical energy, Piezoelectric materials, Power electronics, Switching frequency, Transformers, Vibrations}}, number = {{vol.1}}, pages = {{645--648}}, title = {{{Piezoelectric transformers - state of the art and development trends}}}, doi = {{10.1109/ULTSYM.2002.1193485}}, volume = {{1}}, year = {{2002}}, }