| The ECT (Electrical Capacitance Tomography) technology is one of PT technologies which have developed recent years. This technology gains widespread attention in the identification domain of two phase flows by its advantages, which manifests in non-invasive, the high speed of response and the low cost. Therefore, many technologies which are related to ECT have been studied widely, for instance, how to design ECT system optimally, the calibration research in ECT system, the optimization in ECT image reconstruction algorithm. How to design rational ECT system has become a popular research.The traditional design in ECT system is based on the signal exciting circuit design, the signal enlargement processing design, the full-wave rectification filter processing circuit design as well as the AD circuit design. This system is complex to design, has a high cost, what is more, this system produce parasitic capacity in the compound circuit. The complex level in system design will influence measurement result in sensitivity. So, the ECT system which is highly integrated, low cost as well as has high precision has an advantage against traditional ones.In this thesis, the capacitance information gathering system is designed based on this idea. The system is designed based on an integrated capacitance to digital converter named AD7746coordinating with a32bits ARM chip called STM32F103RBT6. The contents of this thesis are as follows:1. The design of ECT hardware using integrated Capacitance-to-Digital Converter is completed. Specifically speaking, the capacitance gathering circuit in ECT system using an integrated Capacitance-to-Digital converter named AD7746is designed and its PCB is produced; the switching circuit design in ECT system using C8051F310and G5V-1is completed and its PCB is produced, which achieve the transformation between capacitance information of the sensors’plates to digital information.2. The design of ECT software using integrated Capacitance-to-Digital Converter is completed. Specifically speaking, Program (C) in capacitance gathering board and sensors’ plates switching board with the platform of ARM, which achieve to gain capacitance of sensors’ plates; Program (C#) in PC with the platform of visual studio.net, which achieve information interchange between PC to Capacitance gathering board; Program (C#) via GPIB to control4285A-LCR, which achieve the calibration in capacitance of sensors’plates.3. The tasks of simulating sensor models and calculating as well as analyzing their sensitivities with the help of the finite element analysis software are completed. Then, an optimal algorithm is selected with the help of simulated experiments. Specifically speaking, sensor models are modelled and their sensitivities are calculated by sensitivity formula, meantime, the sensitivity images are showed with the help of C++programming in PC and their sensitivities are analyzed. By carrying on simulation experiment with the simulated data gained above, an optimal algorithm is selected finally.4. The ECT systems (Two Parts:Integrated Capacitance-to-Digital Part and4285A-CLR Measuring Instrument Part) are establishedand, meantime, image reconstruction experiments are carried on. Specifically speaking, the image reconstruction show is achieved with the help of C++programming in PC using the measurement capacitance information and sensitivity information calculated above. Finally, the image reconstruction results are analyzed. |
