Study On Electrical Capacitance Tomography System Based On AD7746

Electrical Capacitance Tomography(ECT)is a typical electrical tomography technology.It uses a capacitance-sensitive mechanism to visually analyze the distribution of the medium in the pipeline.Obtaining high-accuracy capacitance data during this process is essential for image reconstruction.In addition,during the image reconstruction process,due to the non-linear distribution of the sensitive field,the reconstructed image in the central region of the pipeline has poor resolution,and the severe ill-condition of the sensitivity matrix also makes it difficult to reconstruct high-quality images.This paper uses the capacitance-to-digital converter(CDC)to design a capacitance measurement circuit to achieve high-precision,accurate,and stable capacitance measurement.The reliability of the measurement is verified by comparison with the simulated capacitance value.In order to improve the sensitivity of the sensitive field,a sensitive field optimization method based on the driving electrode is designed.Aiming at the problem that the imaging effect at the center is poor due to the uneven distribution of the sensitive field,an improvement scheme is proposed to increase the driving electrode.The effect of driving electrode and its excitation voltage on images were studied.The change of potential,the values of sensitivity in the center,the uniformity of the sensitivity distribution and the reconstructed images of different flow regimes under different excitation voltages of driving electrode were compared with the traditional sensor.The results showed that there was an optimal value for the excitation voltage of the driving electrode,which had a significant effect on improving the sensitivity distribution and the image resolution of the central region.