Study On The Capacitance Type Liquid Dielectric Constant Tester

With the development of science and technology, the liquid material has raised people's attention. And the study of the characteristics of the liquid material parameter measurement is constantly deepened. At the same time, people put forward higher requirements to liquid dielectric constant measurement technique such as its accuracy?range and stability. A liquid dielectric constant measuring device with capacitive sensor as the measuring element, simple operation, low manufacturing costs is researched and developed.To achieve the research purpose, systematic and detailed analysis and comparisons,are made about principles of a capacitive sensor and its current situation at home and abroad. A test system based on liquid dielectric constant parallel plate capacitive sensors is designed. the construction of the sensor to determine the size and material selection parameters is designed and completed. In order to improve the accuracy, the position of the ring structure is installed to reduce the influence of the edge effect; drive cable technology in the electric circuit is applied to reduce the influence of parasitic capacitance; temperature compensation technology in software calculations is studied to reduce the impact of temperature by using MATLAB intended for temperature compensation data and calculations.Measuring electric circuit and the parallel plate electric capacity sensor have been designed into sensor electric capacity. And with integrated circuit CAV444, the sensor capacitance is linearly proportional charged into the voltage. SCM system calculates the follow-up voltage signals, the liquid temperature signals, acquises calculation of compensation and other computing-related, and shows the test results are displayed.Various components of SCM hardware's selection and the connect method are completed. And SCM system C language program is competed...