Design of differential-switched-capacitor vortex flowmeter

Abstract

The structure of DSC has a high vibration resistance and a high temperature resistance(up to 400..) and so, a DSC sensor is adopted in the design of a vortex flowmeter, which is mainly comprised of a movable electrode and two fixed electrodes. The movable electrode of DSC is a hollow cylinder and the fixed electrodes are two metal films symmetrically plated on a dielectric cylinder. The air between the movable electrode and the fixed electrodes is the medium of DSC. A Simplified Model is established to research the operation principle of Differential-Switched- Capacitor. Based on the characteristics of vortices, a Differential Switched-Capacitor Converter is adopted, which utilize a electronic analog switch to complete the charge and discharge of the two capacitors alternatively under the control of a clock signal to convert the capacitance signal of DSC into a voltage signal. Experiments are performed on water medium in a pipe of 25mm in nominal diameter. Five calibration points are selected and three tests are performed of each calibration points. Experimental results show that the accuracy of DSC vortex flowmeter is 0.62% and the repeatability error is 0.16%.