Triangular-wave Signal Driven Measuring Circuit in ECT
MA Min1,WU Ke1,HU Ya-feng2,CUI Zi-qiang2,WANG Hua-xiang2
1. School of Electrical Information and Automation, Civil Aviation University of China, Tianjin 300300, China
2. School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China
Abstract：Electrical capacitance tomography measuring circuit requires extremely high sensitivity and dynamic range. The use of triangular-wave signal as excitation signal was proposed to replace the sine-wave signal. Due to the differential characteristics of C/V converter circuit, its output became square wave signal when triangular-wave signal was applied to the measured capacitance. At the same time, the circuit showed good linearity in measuring small capacitance. Transient analysis showed that the settling time was reduced to 0.65μs. In addition, the capacitance acquisition rate could be greatly increased by the removal of phase sensitive detector. For a 12-electrode ECT system, the frame rate could reach up to 3124 frames/s. Experimental results showed that the peak peak value of the measurement sensitivity of the circuit is 0.8 V/pF, and the dynamic range is 69 dB.
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2020, Vol. 41 
