压电变压器的原理及其应用中的关键问题

文章简要介绍了压电变压器的工作原理。着重对压电变压器在应用过程中的关键技术问题做了研究与探讨，并根据压电变压器的特性设计制作出两种实用的电子线路。     

110kV、220kV变压器中性点过电压保护方式探讨

简要介绍了变压器中性点过电压的各种情况，对各种保护方式的原理及存在的问题做了简要分析，并探讨了间隙与避雷器的伏秒特性配合问题。     

压电变压器的研究进展

压电变压器利用压电陶瓷材料自身的压电和逆压电效应来实现升降压，同传统的电磁变压器相比较，具有体积小、无电磁污染、升压比随工作频率和阻抗变化的特点。本文详细评述了用于压电变压器的铁电陶瓷材料的电畴特性、性能参数和掺杂改性的方法，以及压电变压器的变压原理、一般等效电路图和各种各样的压电变压器，分析了现阶段压电变压器存在的问题，并展望了压电变压器的发展方向。     

压电陶瓷变压器研究和发展现状

概述了压电陶瓷变压器的原理和分类，介绍了各种振动模式的压电陶瓷变压器，并重点叙述了两种电极设计精巧的压电陶瓷变压器，对体型和膜型压电陶瓷变压器的研究进展现状进行了分析。     

变压器与音响（下）

在介绍各种常规芯片变压器的特点的基础上,分别介绍了电源变压器、音响变压器对音质的影响及如何应用,以及音频变压器的绕制。最后给出了制作场效应管音端输出变压器的制作。     

变压器与音响（上）

在介绍各种常规芯片变压器的特点的基础上,分别介绍了电源变压器、音响变压器对音质的影响及如何应用,以及音频变压器的绕制。最后给出了制作场效应管音端输出变压器的制作。     

高速动车组牵引变压器线圈制作装备浅析

本文对当今高速动车组牵引变压器的线圈制作工艺及装备选型进行了介绍及分析。给出了变压器线圈制作的工艺及装备选型分析过程．并将选用的装备与普通装备进行对比分析。实践证明,选用的装备使用情况良好。     

PVDF传感器在火炮弹底撞击应力测试中的应用

在分析PVDF压电薄膜测压原理的基础上,提出了利用PVDF压电薄膜测量火炮发射过程中火药颗粒对弹底撞击应力方案,并论述了该方案的可行性.设计并试制了适合火炮膛内发射条件下测量火药颗粒对弹底撞击应力的弹载传感器,重点阐述了传感器结构设计、制作工艺以及PVDF压电薄膜的工程应用技术;设计完成了适合于弹上狭小空间使用的信号调理电路,并对电路进行了仿真及调试.最后初步探讨了影响测量精度的因素并提出改进措施.     

CAT技术应用于变压器例行试验的探讨

介绍了计算机辅助测试（CAT）技术在电工电气试验中的应用。以电力变压器例行试验为例，阐述了一套微机型变压器CAT自动测试系统实现变压器七个例行试验项目基本试验功能的方法，具体探讨了该测试系统在试验数据采集、A／D转换等方面的软、硬件实现过程及CAT技术中的数据管理及测试诊断问题；基于误差理论对试验数据进行误差分析，简要的给出了采用滤波电路对测试误差进行抑制的结果；说明了采用CAT测试系统进行变压器例行试验的可行性、科学性和必然性。     

基于压电陶瓷的自维持压电电源设计与建模研究

为解决浮桥监测系统网络节点供电问题,设计一种新型自维持压电电源,其最大特点是采用了以弹簧-质量块组件为核心的自维持压电结构,它将工作环境产生的机械能转换为振动源,以延长载荷持续效果并延长电源供电时间。阐述了自维持钹式压电电源结构设计,并从材料选择、钹形端帽加工、粘结固定等方面对钹式压电阵列制作工艺进行了描述。最后基于自维持压电结构,在对钹式压电结构受力分析的基础上,利用柱坐标系压电方程推导出自维持压电电源的输出电压、电荷以及电能公式,基于发电模型定性分析了相关参数对发电特性的影响规律。     

Piezoelectric transformer structural modeling--a review

A review on piezoelectric transformer structural modeling is presented. The operating principle and the basic behavior of piezoelectric transformers as governed by the linear theory of piezoelectricity are shown by a simple, theoretical analysis on a Rosen transformer based on extensional modes of a nonhomogeneous ceramic rod. Various transformers are classified according to their structural shapes, operating modes, and voltage transforming capability. Theoretical and numerical modeling results from the theory of piezoelectricity are reviewed. More advances modeling on thermal and nonlinear effects also are discussed. The article contains 167 references.     

Identification of material constants for piezoelectric transformers by three-dimensional,finite-element method and a design-sensitivity method

In this paper, an inversion scheme for piezoelectric constants of piezoelectric transformers is proposed. The impedance of piezoelectric transducers is calculated using a three-dimensional finite element method. The validity of this is confirmed experimentally. The effects of material coefficients on piezoelectric transformers are investigated numerically. Six material coefficient variables for piezoelectric transformers were selected, and a design sensitivity method was adopted as an inversion scheme. The validity of the proposed method was confirmed by step-up ratio calculations. The proposed method is applied to the analysis of a sample piezoelectric transformer, and its resonance characteristics are obtained by numerically combined equivalent circuit method.     

Electrical and mechanical fully coupled theory and experimental verification of Rosen-type piezoelectric transformers

A piezoelectric transformer is a power transfer device that converts its input and output voltage as well as current by effectively using electrical and mechanical coupling effects of piezoelectric materials. Equivalent-circuit models, which are traditionally used to analyze piezoelectric transformers, merge each mechanical resonance effect into a series of ordinary differential equations. Because of using ordinary differential equations, equivalent circuit models are insufficient to reflect the mechanical behavior of piezoelectric plates. Electromechanically, fully coupled governing equations of Rosen-type piezoelectric transformers, which are partial differential equations in nature, can be derived to address the deficiencies of the equivalent circuit models. It can be shown that the modal actuator concept can be adopted to optimize the electromechanical coupling effect of the driving section once the added spatial domain design parameters are taken into account, which are three-dimensional spatial dependencies of electromechanical properties. The maximum power transfer condition for a Rosen-type piezoelectric transformer is detailed. Experimental results, which lead us to a series of new design rules, also are presented to prove the validity and effectiveness of the theoretical predictions.     

Vibration distribution in output sections of a piezoelectric transformer operating at thickness shear mode

In this study, the vibration distribution along the width direction in the output section of a piezoelectric transformer operating at the thickness shear vibration mode is investigated experimentally and theoretically. It is experimentally found that the vibration of output section has a spatial gradient and attenuates as the distance from the input section increases. A theoretical model is developed to estimate the vibration attenuation in the output section, which provides the guidelines of optimizing the transformer and explains some important phenomena such as the nonuniform temperature distribution in piezoelectric transformers. The larger the load resistance, the larger the vibration gradient is. At the resonant frequency, the vibration gradient decreases with increasing the width of the input or output section, and it changes little with the length and thickness of the transformer when the load resistance matches with the piezoelectric transformer. The vibration gradient increases with increasing the length or decreasing the thickness when the load resistance is constant, in which the load does not match with the transformer.     

Modeling of piezoelectric transformers using finite‐element technique

Abstract

In this work, the modeling of piezoelectric transformers using the finite‐element technique is presented. A 3‐D finite element method solver, which employs 20‐node brick‐element formulation, is developed. Using the solver, the characteristics of piezoelectric transformers under different operating frequencies can be simulated. Also, the solver is capable of accounting for the effects of the electrical loadings attached to the output electrodes of piezoelectric transformers. The modeling results for two different types of piezoelectric transformers, the Rosen‐modal‐type and the unipoled‐disk‐type, are presented. For the Rosen‐modal‐type devices, the simulated voltage gains and the phase differences are validated with our measured results. Also, the simulated results of the unipoled‐disk‐type transformers agree with the measured results found in previously published literature. The effects of electrical loadings on these piezoelectric transformers are also discussed.     

Multilayer modal actuator-based piezoelectric transformers

An innovative, multilayer piezoelectric transformer equipped with a full modal filtering input electrode is reported herein. This modal-shaped electrode, based on the orthogonal property of structural vibration modes, is characterized by full modal filtering to ensure that only the desired vibration mode is excited during operation. The newly developed piezoelectric transformer is comprised of three layers: a multilayered input layer, an insulation layer, and a single output layer. The electrode shape of the input layer is derived from its structural vibration modal shape, which takes advantage of the orthogonal property of the vibration modes to achieve a full modal filtering effect. The insulation layer possesses two functions: first, to couple the mechanical vibration energy between the input and output, and second, to provide electrical insulation between the two layers. To meet the two functions, a low temperature, co-fired ceramic (LTCC) was used to provide the high mechanical rigidity and high electrical insulation. It can be shown that this newly developed piezoelectric transformer has the advantage of possessing a more efficient energy transfer and a wider optimal working frequency range when compared to traditional piezoelectric transformers. A multilayer piezoelectric, transformer-based inverter applicable for use in LCD monitors or portable displays is presented as well.     

夹心式压电陶瓷超声换能器的非线性研究进展

夹心式压电陶瓷超声换能器是目前大功率超声设备中应用最广的一种换能器,其在大功率工作状态下会呈现出明显的非线性特征。综述了夹心式压电陶瓷超声换能器非线性方面的研究进展。首先介绍了国内外在压电陶瓷非线性方面的重要理论及实验研究成果,着重阐述了大功率领域常用的硬压电陶瓷的非线性研究工作,其次对夹心式压电陶瓷超声换能器的结构及工艺所引起的非线性进行了简要分析和论述,最后介绍了夹心式压电陶瓷超声换能器非线性建模方面的研究进展。     

Development of advanced heat transformers utilizing new working fluids

Based on experience from an industrial-scale heat transformer, which is now commercially available, GEA has embarked on a new research and development programme: the development of an advanced heat transformer and investigation into the combination heat transformer/absorption heat pump. Advanced heat transformers are heat transformers utilizing new working fluids and/or a multi-stage absorption plant. A brief report is presented on an experimental research programme at the University of Essen which aims to discover new working fluids for sorption plants. Some of the most important results for heat transformer application are presented in the form of graphs or tables and the suitability of the new working fluids is compared with some well-known working couples. The Industrial requirements for an advanced heat transformer are also considered along with the possibility of meeting these requirements. Finally, the heat transformer is discussed in the context of other heat recovery systems on the basis of two fictitious industrial applications.     

Power density of piezoelectric transformers improved using a contact heat transfer structure

Based on contact heat transfer, a novel method to increase power density of piezoelectric transformers is proposed. A heat transfer structure is realized by directly attaching a dissipater to the piezoelectric transformer plate. By maintaining the vibration mode of the transformer and limiting additional energy losses from the contact interface, an appropriate design can improve power density of the transformer on a large scale, resulting from effective suppression of its working temperature rise. A prototype device was fabricated from a rectangular piezoelectric transformer, a copper heat transfer sheet, a thermal grease insulation pad, and an aluminum heat radiator. The experimental results show the transformer maintains a maximum power density of 135 W/cm(3) and an efficiency of 90.8% with a temperature rise of less than 10 °C after more than 36 h, without notable changes in performance.