【作者】 邱桂苹；

【导师】 于晓洋；

【作者基本信息】 哈尔滨理工大学 ， 测试计量技术及仪器， 2007， 硕士

【摘要】 层析成像技术是近年来发展起来的一门新兴的过程检测技术,该项技术在解决多相流检测问题上有巨大的发展潜力和广阔的工业应用前景。其中,电容层析成像技术(ECT)以其成本低、适用范围广、结构简单、非侵入式、安全性能好等优点,成为目前该领域中发展的主流和研究热点,但离实际应用尚有一段距离,因此有待进一步研究和发展。由于电容测量问题是影响电容层析成像系统测量精度和重建图像质量的关键和难点之一,所以对微小电容测量电路的研究是极为重要的。并且电容层析成像系统要求实时处理数据,则对数据采集与处理的速度也有较高的要求。因此,本文针对ECT系统中电容测量电路及其测量数据采集系统进行研究。本文在对目前应用于电容层析成像系统中的几种测量电路进行分析讨论的基础上,选择一种交流激励电容测量电路应用于电容层析成像系统中。重点对交流激励电容测量电路的测量原理、抗杂散性和原理误差进行理论分析。鉴于数字信号处理器件(DSP)具有较快的运行速度和强大的数据处理能力等优点,设计基于DSP芯片的ECT系统电容测量数据采集系统。系统包括正弦信号发生器、C/V转换电路、交流放大电路、全波整流电路、低通滤波电路、A/D转换电路、传感器极板间切换电路以及系统通讯接口等。由于ECT系统中电容的变化范围为pF数量级,对电容测量电路要求高,所以,在建立交流激励电容测量电路数学模型的基础上,通过仿真实验,对交流激励电容测量电路的主要参数进行优化。为提高交流激励电容测量电路的性能提供基础。更多还原

【Abstract】 The imaging technique is a new process detection technology developed in recent years, which has great development potential and wide industrial application prospect. In which , Electrical Capacitance Tomography(ECT) has many advantages such as low cost, wide application field, simple structure, non-invade and better safety. It has being the most popular research direction and the main development in flow imaging technique. Since it has some distance to the reality applies, studying and developing should be doing further.The capacitance measuring problem is one of the key and difficulties which can influence the accuracy and reconstruction image quality of ECT system. It is extremely important to the research of small electrical measuring circuit. And ECT system requests real-time transmission data. So it has high request to the data acquisition and the processing speed. Therefore, the thesis is aimed at capacitance measuring circuits and data acquisition system in the ECT system.The thesis chooses a kind of AC measuring circuit to apply in ECT system based on the anglicizing and studying on several kinds of measuring circuits carries about ECT system. Emphases mainly studies in the AC measuring circuit’s measuring principle, the anti-stray and the principle error carry on the theories analysis in the thesis.ECT Measuring and Data Collecting System is based on the DSP in view of the digital signal processing component (DSP) which has high running speed and formidable data processing ability etc. System includes sine wave signal generating device, C/V conversion circuit, A/C amplificatory circuit, full-wave rectification circuit, low-pass filter circuit, A/D conversion circuit, the circuit for switching the capacitor of electrodes and system communication connection and so on.Because in the ECT system the capacitance range of variation is pF magnitude, it needs higher precision to measuring circuit. the mainly parameter of measuring circuit is being optimized during the simulation experiment based on the mathematical model of capacitance measuring circuit, therefore, it provides the foundation for the A/C measuring circuit performance.更多还原