Step-down piezoelectric transformer for AC-DC converters

Citation
M. Yamamoto et al., Step-down piezoelectric transformer for AC-DC converters, JPN J A P 1, 40(5B), 2001, pp. 3637-3642
Citations number
12
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Volume
40
Issue
5B
Year of publication
2001
Pages
3637 - 3642
Database
ISI
SICI code
0021-4922(200105)40:5B<3637:SPTFAC>2.0.ZU;2-1
Abstract
In this paper, a new piezoelectric transformer for AC-DC converters is pres ented. This piezoelectric transformer, with a multilayered construction in the thickness direction, operates in a fundamental contour-extensional vibr ation mode. Output impedance is designed to be low, approximately several t ens of ohms. First, we simulated the design of the transformer using equiva lent circuit method and finite element method (FEM) analyses. We calculated that the transformer could work with an eficiency higher than 95% and a ga in of 0.4 at a resonant frequency of 140 kHz. Second, we fabricated a trans former of 14 mm, length, 14 mm width and 5.8 mm thickness and examined it. It was found that the transformer exhibited a 0.4 gain and 96.3% efficiency at 135 kHz, when the temperature increase was 30 degreesC, We applied the transformer to the fabrication of an AC-DC converter using a half-brid.-e z ero voltage switching circuit, and examined the converter. It was found to achieve good line and load regulation, and the highest efficiency of 90% wa s obtained for V-in = 80-120 V-ac,V- V-out = 13 V-de, and I-out, = 0.8-1.5 A.