Development of Very High Voltage Transformers Using Piezoelectric Single Crystals

本研究项目的目的是提出适用于大幅值运行的电致变电型LiNbO_3单晶变压器，并研制出具有高阶跃比的小型变压器。本课题的研究成果总结如下：1.为了寻找变压器的最佳切割方式，计算了相关机电耦合系数的方位依赖关系。结果表明，最佳方向是130。纵向联轴器输出配置和140的旋转Y形切割。横向联轴器输出配置的旋转Y形切割。2.测量了LiNbO_3振子的大振幅特性。与陶瓷相比，LiNbO_3的损耗较小，在大幅值工作时，性能几乎没有恶化。3.对含有非线性二极管整流电路和负载电阻的压电变压器的特性进行了理论分析。明确了电压阶跃比、输出电流和输出功率与负载电阻的关系。4.研制了一种纵向耦合输出结构的变压器，其阶跃比约为500，输出电压不饱和，最高可达5KV。发现并定性地解释了输出特性随极板表面与输出电极的极性的不同而不同的事实。5.一种采用140横向耦合输出配置的LiNbO_3变压器。设计并证明了旋转Y形切割器具有高输出电流和约1300.6的高阶跃比。在154.5。旋转Y切LiNbO_3矩形板，理论上预言了在四角有振动节点的跛模的存在和高度的激振性。结果表明，即使在四边支承的情况下，跛行模式变压器仍具有很高的Q值超过10000，阶跃比超过700时。7.一台微型跛脚机

The purpose of this research project to propose riezoelectric LiNbO_3 single-crystal transformers suitable for large amplitude operation and to develop small-size transformers with a high stepup ratio. The results obtained in this project are summarized as follows : 1. To find the optimum cuts for transformers the orientation dependence of the relevant electromechanical coupling factors was calculated. The optimum orientation turned out to be the 130。 rotated Y-cut for the longitudinal coupling output configuration and the 140。 rotated Y-cut for the transverse coupling output configuration. 2. The large-amplitude characteristics of LiNbO_3 vibrators were measured. LiNbO_3 has small losses compared to those of ceramics and exhibits little deterioration of performance under large amplitude operation. 3. The behavior of piezoelectric transformers including a rectifying circuit with nonlinear diodes and a load resistance was theoretically analyzed. The dependence of the voltage stepup ratio, output current, and output power on the load resistance was made clear. 4. A transformer of longitudinal coupling output configuration with a high stepup ratio of about 500 and with no saturation of the output voltage upto 5kV was developed. The fact that the output characteristics differed depending on the polarity of the plate surface with the output electrode was found and qualitatively explained. 5. A LiNbO_3 transformer of the transverse coupling output configuration using the 140。 rotated Y-cut was devised and demonstrated to have a high output current and a high stepup ratio about 1300.6. In 154.5。 rotated Y-cut LiNbO_3 rectangular plates, the Lame-modes which have vibration nodes at the four corners were theoretically predicted to exist and to be highly excitable. It was demonstrated that the Lame-mode transformer has a very high Q over 10000 and a high stepup ratio over 700 even if it is supported on the four edges. 7. A miniature Lame-m