PMN-PZN-PZT 세라믹스를 이용한 적층형 압전변압기의 전기적 특성

Abstract

Dielectric and piezoelectric properties of PMN-PZT ceramics with a high mechanical quality factor<TEX>$(Q_m)$</TEX> and a low temperature sintering temperature were investigated as a function of PZN substitution in order to develop multilayer piezoelectric transformer for AC-DC converter. Multilayer piezoelectric transformers were subsequently manufactured using the PMN-PZN-PZT ceramic offering the optimal behavior and then the electrical performance were invetigated. At the sintering temperature of <TEX>$940^{\circ}C$</TEX>, density, electromechanical coupling factor<TEX>$(k_p)$</TEX>, mechanical qualify factor<TEX>$(Q_m)$</TEX> and dielectric constant<TEX>$(\varepsilon_r)$</TEX> of 8 mol% PZN substituted specimen were <TEX>$7.73g/cm^3$</TEX>, 0.524, 1573 and 1455, respectively. The PZN substitution caused a increase in the dielectric constant and the electromechnical coupling factor. The voltage step-up ratio of multilayer piezoelectric transformer showed the maximum value at near the resonant frequency of 76.55 kHz and increased according to the increase of load resistance. The multilayer piezoelectric transformer with the output impedance coincided with the load resistance showed the temperature increase of less than <TEX>$20^{\circ}C$</TEX> at the output power of 10 W. Based on the results, the manufactured multilayer transformer using the low temperature sintered PMN-PZN-PZT ceramics can be stably driven for both step-up and down transformers.