直驱喷油器中压电执行器的迟滞非线性特征研究

发布时间：2018-05-18 22:39

本文选题：压电直驱喷油器 + 迟滞非线性　；参考：《浙江大学》2016年硕士论文

【摘要】：基于压电执行器直接驱动的电控喷油器能有效地实现高压燃油的精确喷射,对于大幅提高发动机的燃油效率、降低运转噪声、减少有害物排放具有重要的现实意义。与此同时,压电陶瓷材料作为一种特殊的多晶铁电材料,其本身独有的迟滞非线性特征及依赖于负载加载频率和偏置应力的动力学行为也给压电执行器的建模与控制带来了巨大的挑战。本文基于压电直驱喷油这一工程应用背景,对压电陶瓷内部的电畴结构及极化翻转过程进行了深入分析,并从电畴的极化翻转角度给出了迟滞非线性的形成机理。结合现有迟滞模型的优缺点以及工程控制领域的实际需求,本文提出了一种基于朗道相变理论的动态微分方程模型,旨在为基于模型的控制算法设计提供理论支持。本文通过构建一个非凸本构关系,并通过非凸本构关系在系统动力学中引入分岔,成功实现了对迟滞非线性行为及其对偏置应力和加载频率依赖性的模拟。主要内容概括如下：第一章,主要介绍了论文的研究背景与研究意义,详细说明了当前压电喷油器的优势以及技术瓶颈所在,分别介绍了当前国内外的主流压电喷油器产品及研究成果。最后引出本文的研究目标,即建立一个用于描述压电陶瓷迟滞非线性行为,且适用于工程控制的模型。第二章,本章详细介绍了压电陶瓷材料的迟滞非线性特征及其形成机理。简要阐明了压电陶瓷材料中压电效应、电致伸缩效应以及铁电效应之间的区别与联系。并从材料的微观层面深入分析了自发极化、电畴结构及其重定向过程,从电畴的极化翻转角度给出了迟滞非线性的成因及其特点。简单介绍了当前应用与研究较多的各类迟滞非线性模型,并对比分析了各个模型的优缺点,为之后的研究分析及模型的建立打下理论基础。第三章,本章以朗道相变理论为基础,建立起一个耦合的非线性常微分方程模型。通过非凸本构关系引入动力学分岔,实现对压电单晶迟滞非线性行为的准确描述。在单晶模型基础上,本文基于多晶材料的物理属性,通过引入电畴分布的权重函数构建了多晶耦合模型。最后,本章系统地给出了单晶模型与多晶模型的参数辨识策略,即基于最小平方误差的参数辨识过程。第四章,本章在模型建立和参数辨识基础上,本章对模型的应力依赖性和频率依赖性进行的数值仿真,并与实验数据进行了对比,进一步阐明了动态微分模型的优越性。第五章,对论文所做的研究工作进行了总结,并对将来进一步的研究工作做了相应的展望。
[Abstract]:The electrically controlled injector based on piezoelectric actuators can effectively realize the accurate injection of high-pressure fuel, which is of great practical significance to greatly improve the fuel efficiency of the engine, reduce the running noise and reduce the emission of harmful substances. At the same time, piezoelectric ceramic materials as a special polycrystalline ferroelectric materials, Its unique hysteresis nonlinear characteristics and dynamic behavior dependent on load loading frequency and bias stress also pose a great challenge to the modeling and control of piezoelectric actuators. In this paper, based on the engineering application background of piezoelectric direct drive oil injection, the domain structure and polarization reversal process in piezoelectric ceramics are deeply analyzed, and the formation mechanism of hysteresis nonlinearity is given from the angle of polarization flipping of electric domains. Based on the advantages and disadvantages of the existing hysteresis models and the practical requirements in the field of engineering control, a dynamic differential equation model based on Landau's phase transition theory is proposed in this paper, which aims to provide theoretical support for the design of model-based control algorithms. By constructing a nonconvex constitutive relation and introducing bifurcation into the system dynamics, this paper successfully simulates the hysteresis nonlinear behavior and its dependence on the bias stress and loading frequency. The main contents are summarized as follows: in the first chapter, the research background and significance of the thesis are introduced, and the advantages and technical bottlenecks of the piezoelectric injector are explained in detail. The main piezoelectric injector products at home and abroad and their research results are introduced respectively. Finally, the purpose of this paper is to establish a model for describing the hysteresis nonlinear behavior of piezoelectric ceramics, which is suitable for engineering control. In chapter 2, the hysteresis nonlinearity and formation mechanism of piezoelectric ceramics are introduced in detail. The differences and relations among piezoelectric effect, electrostrictive effect and ferroelectric effect in piezoelectric ceramics are briefly explained. The spontaneous polarization, domain structure and their reorientation are analyzed from the microcosmic level of the material. The causes and characteristics of hysteresis nonlinearity are given from the angle of domain polarization reversal. This paper briefly introduces various kinds of hysteresis nonlinear models which are widely used and studied at present, and compares and analyzes the advantages and disadvantages of each model, which lays a theoretical foundation for the later research and analysis and the establishment of the model. In chapter 3, a coupled nonlinear ordinary differential equation model is established based on Landau's theory of phase transition. The nonlinear hysteresis behavior of piezoelectric single crystal is accurately described by introducing dynamic bifurcation into nonconvex constitutive relation. Based on the single crystal model and the physical properties of the polycrystalline material, the coupling model is constructed by introducing the weight function of domain distribution. Finally, in this chapter, the parameter identification strategies of single crystal model and polycrystalline model are given systematically, that is, the process of parameter identification based on least square error. In chapter 4, on the basis of model establishment and parameter identification, the numerical simulation of stress dependence and frequency dependence of the model is carried out, and compared with the experimental data, the superiority of the dynamic differential model is further illustrated. In the fifth chapter, the research work is summarized, and the future research work is prospected.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U464

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