压电陶瓷变压器CCFL背光电源研究

以压电陶瓷变压器为升压器件，以脉宽调制器（PWM）和MOSFEET管所组成的开关振荡器为驱动电．路，研制出适用于液晶显示器的压电陶瓷变压器背景光高压电源。由于压电陶瓷变压器具有体积小、重量轻、不会打火、不会燃烧、不怕短路等优点，不仅提高了液晶显示器整机的可靠性，而且能适应当前电子产品小型化、轻型化的发展需要。     

压电陶瓷变压器材料的研究与发展

从压电变压器材料的角度叙述了:压电变压器材料研究与发展;压电变压器对其材料性能的要求;现有常用的各系列压电陶瓷变压器材料及其特点;今后的发展。     

大功率压电变压器用压电陶瓷材料发展现状

随着科学技术的进步和压电变压器在生产中的应用，压电陶瓷变压器逐渐向“大功率”、“小型化”方向发展，对压电陶瓷材料提出了更高的要求，简而言之就是“双高”及“双低”，即高“Qm”、高“Kp”和低“tanδ”、低“TCf，”。同时为降低生产成本，压电陶瓷材料应具有尽可能低的烧结温度。本文即以此为中心，对我国大功率压电材料的生产及发展现状、各项性能的影响因素及其成份选择原则做出了相应的讨论。     

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。     

锰掺杂对PMN-PT陶瓷介电和压电特性的影响

采用氧化物固相反应法制备了Mn掺杂0.67Pb（Mg1/3Nb2/3）O3-0.33PbTiO3陶瓷，研究了锰掺杂量对陶瓷相结构、介电和压电性能的影响。实验发现，随着锰掺杂量的增加，陶瓷焦绿石相含量的逐渐较少，材料变“硬”。即当锰掺杂量少于1.5mol％时，介电系数ε、压电常数d33和机械品质因数Qm逐渐增加，介电损耗tanδ减少。随着锰掺杂量的进一步增加，弛豫程度变得更加明显。当压电陶瓷组分中锰掺杂量为1.5mol％时，其介电和压电性能各为：ε=2300，kp=0.54，Qm=900，tanδ=0.004，d33=400pC/N，适于制作大功率压电陶瓷变压器。     

功能陶瓷材料研究的若干进展

本文介绍了几种典型铁电、压电陶瓷及其多层片式元件应用研究的若干新进展。基于过渡液相烧结机制的压电陶瓷材料具有烧结温度低、压电常数和介电常数高，介质损耗低等诸多优点。低烧多层压电变压器(MPT)以其低驱动电压、小体积、高升压比、薄型片式化等优点在液晶显示背光电源等方面获得应用。多层压电变压器及其背光电源具有高功率密度、高转换效率、薄型化和低成本等特点，通过有限元分析和多普勒激光扫描测振仪对MPT的振动模态与机电谐振特性等进行了分析与测定，为结构与性能优化提供了理论与实验依据。研究了钛酸钡基高介电常数温度稳定型多层陶瓷电容器(MLCC)及薄层贱金属内电极MLCC的关键材料组成以及制备技术，基于缺陷化学原理和无晶粒长大的致密化烧结动力学，通过调控受、施主掺杂和两段法烧结工艺，制备了在还原气氛烧结亚微米／纳米晶钛酸钡基陶瓷及其细晶化贱金属内电极MLCC。研究了多层复合功能陶瓷共烧行为、异质界面互扩散、致密化速率调控机制及共烧匹配技术，借助于差热膨胀仪研究了铁电陶瓷介质和内电极共烧失配的动力学根源，为制备高可靠的MLCC等多层元器件提供实验与理论依据。介绍了压电陶瓷超声微马达的结构与特性。     

从发明专利看无铅压电陶瓷的研究与发展——无铅压电陶瓷20年发明专利分析之一

无铅压电陶瓷的研究与开发已引起世界各国的高度重视。本文综合分析了近20年无铅压电陶瓷发明专利约140篇。从发明专利角度评述了无铅压电陶瓷的研究与发展现状，简要介绍了目前受到广泛研究的BaTiO3(BT)基无铅压电陶瓷、Bi1/2Na1/2TiO3(BNT)基无铅压电陶瓷、铋层状结构无铅压电陶瓷及铌酸盐系无铅压电陶瓷，并侧重介绍这些无铅压电陶瓷的组分、性能和制备方法。从无铅压电陶瓷发明专利的进展可以看出，在过去20年中，为促进人类社会的可持续发展，无铅压电陶瓷得到了广泛的研究和开发，并取得重要进展。     

基于压电效应的人工耳蜗的实验研究

为了提高聋耳的听力，将压电材料植入到耳蜗内，利用压电效应直接将声波转化为电信号刺激听神经，以提高听力．本研究通过未极化与极化的高灵敏性压电陶瓷的对比，从体外模拟实验中的声电响应曲线和动物体内植入实验的结果中得到：未极化的压电陶瓷没有压电响应，而极化后的压电陶瓷能够将声音信号转化为电信号，证实了压电陶瓷的压电特性的确可以刺激动物的听神经，从而降低听阈阈值．比较了压电陶瓷与压电高分子之间的差异，结果表明压电高分子也可以刺激听神经来提高听力．     

基于电流控制的压电陶瓷驱动器

为了解决电压控制型压电陶瓷驱动器驱动压电陶瓷时存在的迟滞、蠕变和带宽窄的问题，设计了基于电流控制的压电陶瓷驱动器，利用压电陶瓷致动器位移与其所带电荷量间的线性关系，该驱动器通过控制压电陶瓷的充电电流和时间控制其位移量．在此基础上，提出了以分辨率换取稳定性的动态保持控制方法，采用该电流型驱动器，实现了开环下对压电陶瓷致动器的稳定、快速、高精度定位．实验结果表明，该驱动器驱动行程为10μm的压电陶瓷时，满行程带宽大于1．5kHz，重复定位精度小于4nm（0．4％）．     

应变反馈式压电陶瓷微位移驱动器的研制

介绍了采用应变片测量压电陶瓷微位移驱动器位移的原理和设计思想，介绍了实验装置的结构，给出了实验结果，证明将应变片直接粘贴在压电陶瓷基体表面测量其位移的方法是可行性的；通过对压电陶瓷滞回特性的测定，提出了建立压电陶瓷的控制模型的基本思路。     

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.     

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.     

压电陶瓷变压器的发展——回顾与展望

文章简要介绍了压电变压器的工作原理 ,给出了压电变压器几个重要工作特性的数学表达式 ,并对压电变压器的发展过程进行了简要的回顾。在此基础上 ,文章着重对压电变压器在研发过程中所涉及的五个方面的问题进行了详细的探讨与说明 ,作者讨论了压电变压器等效电路模型的改进措施及压电变压各个特性的研究状况 ,分析和对比了各种用于制作压电变压器的压电材料的优缺点及其性能的改进方法 ,探讨了各种振动模式作用于压电变压器的效果 ,总结了压电变压器的制作工艺及结构对其特性的影响效果 ,给出了压电变压器的具体应用的例子 ,并指出了压电变压器今后的发展方向及有待解决的问题     

Comment on Y.-H. Hsu et al., "Electrical and mechanical fully coupled theory and experimental verification of rosen-type piezoelectric transformers"

This letter discusses the difference between piezoelectric constitutive relations for the case of one-dimensional stress and the case of one-dimensional strain, and its implications in the modeling of Rosen piezoelectric transformers     

Comment on Y.-H. Hsu et al., "electrical and mechanical fully coupled theory and experimental verification of Rosen-type piezoelectric transformers" [see reference [1]]

This letter discusses the difference between piezoelectric constitutive relations for the case of one-dimensional stress and the case of one-dimensional strain, and its implications in the modeling of Rosen piezoelectric transformers.     

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.     

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.     

Nonlinear processing of the output voltage of a piezoelectric transformer

Reducing the size of power supplies raises the problem of new components that could be better candidates for integration. In this field, electromagnetic transformers may be replaced with significant benefit by piezoelectric transformers (PT). In a PT, the input electrical energy is transferred to the output by an acoustical means, using the direct and converse effects of piezoelectric materials. Its main advantages over an electromagnetic transformer are no magnetic noise generation, small size, high power density, and high efficiency. This paper deals with an innovative technique that produces a significant improvement of the power capability of piezoelectric transformers. This technique is based on a particular output voltage processing of the PT. Its effect is a vibration level reduction of the PT structure while keeping the output power practically constant. Vibration level is a critical parameter that determines the maximum power capability of a given PT. Thus, the new processing reduces significantly the losses of the PT. Both theoretical predictions and experimental results show that the increase of the power capability may reach 200%.     

Equivalent network representation for thickness vibration modes in piezoelectric plates with a linearly graded parameter

Equivalent network representation is derived for thickness vibration modes in piezoelectric plates with a linearly graded parameter. The network is composed of a transmission line of a finite length, which is linked to the electric excitation port via ideal transformers connected serially at both ends. The ratios of the two transformers are different from each other and frequency dependent. Two frequency-dependent capacitors of the same value but opposite sign appear at the electric port. The frequency characteristic of the input electric admittance of the resonator, which shows the unique feature of the graded piezoelectric plate, is demonstrated by the equivalent network analysis.     

Analysis of rosen piezoelectric transformers with a varying cross-section

We study the effects of a varying cross-section on the performance of Rosen piezoelectric transformers operating with length extensional modes of rods. A theoretical analysis is performed using an extended version of a one-dimensional model developed in a previous paper. Numerical results based on the theoretical analysis are presented.