电容传感器在粮食水分检测中的应用论文.doc

二○○九届毕业设计 存档编号： 毕 业 设 计 论文题目 电容传感器在粮食水分检测中的应用 （英 文）Matlab仿真；检测电路 Abstract The technology of moisture measurement is a synthetic technology relating to many subjects.During the past several decades,by the researchers hardwork,some prominent successes have been achieved.Whereas,due to the influences of several other factors in moisture measurement,the measurement precision and the repeatability are not satisfied.In the thesis，more advanced method and exploring study is carried out.These provide new ideas for the design of the moisture measurement sensor.The major points of the thesis include: (1)It analyzes the medium property of grain.The principles of current moisture instruments are analyzed and their merits and defects are pointed out. (2)It also establishes the physical model of capacitive grain moisture sensor by using mechanism modeling theory and deduces the mathematical model for its capacitance parameters and moisture content of measured grain. (3)The Matlab and analysis of mathematical model are also presented.And then a measuring circuit of the capacitive sensor is designed. (4)It also obtains the equivalent circuit of sensor by using electric conductivity bathtub effect of grain, analyzes the factors that may influence the capacitance of sensor. Key Words Grain Moisture;Capacitive Sensor;Mathematical Model;Matlab;Measuring Circuit 目 录 摘 要 ...................................................................1 Abstract..................................................................2 0.绪 论 5 0.1粮食中的水分及粮食介电特性分析 5 0.2粮食水分检测的意义 6 0.3国内外水分检测水平 7 1.水分测量方法概述 7 1.1干燥法 8 1.1.1电烘箱法 8 1.1.2干燥称重法 8 1.1.3红外烘干法 8 1.2化学法 9 1.2.1蒸馏法 9 1.2.2卡尔·费休法 9 1.3射线法 9 1.3.1红外线法 9 1.3.2微波法 10 1.4电测法 10 1.4.1电导法 10 1.4.2电容法 11 2.电容传感器的数学建模 11 2.1　电容传感器的基本工作原理及物理模型 11 2.1.1 电容传感器基本工作原理 11 2.1.2 电容传感器的物理模型 12 2.1.3 电容式水分传感器的结构优化 13 2.2 传感器数学模型的建立 14 3.传感器的数学模型Matlab仿真及其检测电路的设计 16 3.1数学模型的Matlab仿真 16 3.2电容传感器检测电路的设计 19 3.2.1 电容传感器特点及常用测量方法 19 3.2