A resonant, frequency - tracking, step-down piezoelectric transformer based converter

This paper presents the experimental modeling of a Step-Down DC/DC, thickness vibration mode type Piezoelectric Transformer (PT), intended for commercial applications. The paper includes the analysis, design and control process of a power converter topology to drive the PT. The objective is to achieve a good balance between efficiency, cost, robustness and minimization of magnetic components. The converter is designed to work at the PT most interesting resonant frequency achieving frequency tracking with load, temperature and component values variation, by means of indirect measurement of mechanical vibrations of the piezoelectric transformer. The modeling of the chosen PT was experimentally validated by using an impedance analyzer. The whole system was tested using SPICE with real switches and components. Based in the theoretical concepts a laboratory prototype was designed and built. The experimental and simulated results are presented to confirm the adopted theoretical principles and design criteria.