ECT System Capacitance Measuring Circuit Simulation And Its Data Collects System Design

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.