LiNbO3 piezoelectric transformer for power transmission

A single-crystal LiNbO₃ piezoelectric transformer having a 140° rotated Y-cut plate that uses the longitudinal vibration of the transverse effect was studied. The results of the equivalent circuit and analysis and experiments conducted on symmetrical devices having electrodes of the same length and asymmetrical devices having electrodes of different lengths are presented. When driven with a constant voltage, the dependence of the voltage transformation ratio on load resistance differs when the load resistance is below or above about 10 kΩ. In the low-load-resistance range, the voltage transformation ratio does not depend on the load resistance and is determined by the ratio of electrode lengths. The transformation characteristics measured closely match the calculated value when the elastic loss at the support and the floating capacitance of the electrodes are considered. A minimum resonant resistance of 9 Ω was exhibited by an element measuring 32 (L)×12 (B)×0.5 (T). The maximum transmitted power was about 1 W for a device having a 12-mm element