Development of Very High Voltage Transformers Using Piezoelectric Single Crystals

本研究计画的目的是提出适用于大振幅工作的铌酸锂单晶变压器，并发展小型化、高升压比的变压器。本项目取得的主要成果如下：1.为了找到变压器的最佳切割，计算了相关机电耦合因子的取向依赖性。最佳方向是130度。纵向耦合输出配置和140.横向耦合输出配置的旋转Y形切割。2.测量了LiNbO_3振子的大振幅特性。LiNbO_3与陶瓷相比具有较小的损耗，并且在大幅度操作下性能几乎没有劣化。3.对由非线性二极管整流电路和负载电阻组成的压电变压器的特性进行了理论分析。明确了电压升压比、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Transformer，升压比可达500左右，输出电压在5 kV以下不饱和。发现并定性解释了输出特性随输出电极板面极性不同而不同的事实。5.采用140.旋转Y切割被设计并被证明具有高输出电流和约1300.6的高升压比。在154.5中。在旋转Y切LiNbO_3矩形板中，理论上预言了存在四角振动节点的Lame模，并且是高度可激发的。结果表明，即使在四边支撑的情况下，Lame模式Transformer仍具有超过10000的高Q值和超过700的高升压比。7.一个微型的Lame-m

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