Research On New Capacitance-to-Digital Ice Thickness Sensor And Its Monitoring Method

This thesis is an applicable basic research which is funded by the program of National Natural Science Foundation, "Research on Ice Thickness Sensor and Its Monitoring Method" (60672028), and graduate students key program of Shanxi Province outstanding innovation in 2008, "Electricity Network of Remote Monitoring System of Ice-Coating Thickness Based on Differences Between Air and Ice Physical Properties" (20081009).Frozen natural disaster happened in South China region in 2008. Ice-floe hazards burst in the Hukou Waterfall of Yellow River in 2009. Cause of the cold winter in 2010, ice area in both Yellow River Valley and Bo Sea Bay is more than the historical record. Global warming, melting glaciers, rising sea levels and so on, a series of climate changes have impacted on people's normal life and production. Nature is frequently sounded the alarm bell for us. How to send warning signals before the disasters come? How to take precaution for disaster prevention before tragedies occur? This requires real-time monitoring of ice thickness, to keep abreast of freezing and thawing changes of snow and ice. In view of this, a new method based on the capacitance characteristics differences among air, water and ice is propounded, which converts capacitance value to digital signal directly.Based on the technological reports from out Laboratory's early research result, there is an error when a resistance-type ice thickness sensor is used for distinguishing the interface between water and ice, or between air and ice. In order to reduce this undesirable error, I discuss the advantage and disadvantage of the resistance-type ice thickness sensor. Thus, I contrive a new capacitance-to-digital ice thickness sensor. Furthermore,because of the serious drawback which is made during the process of the typical AC capacitance measurement and transmission, I propose a detection system for measuring ice thickness, which achieves the function by utilizing capacitance-to-digital converter. This converter can convert capacitance value to digital signal directly and transmits it to the detection system. However, the input capacitance range of CDC, currently available in the market, is much smaller than our experiment result's. To be suitable for the measure range of CDC, sensor's structure and material need to be improved. The new capacitance ice thickness sensor model adopts a ruler structure of vertical double line plates. Experiments show that we should keep CDC's input capacitance range under certain requirements, if we do this as follows. Add an insulation layer to the outer layer of sensor's detection plates for isolation from the measured object. Directly connect chip AD7747 to the sensor and place them in the same measurement conditions. When the intelligent data processing system, whose core is a MCU, receives the measured sensor capacitance data, it can calculate the interface of ice, water and air, namely ice thickness, by judging program embedded in the system.This sensor has the characteristics of simple structure, easy installation, and strong anti-interference. Solar power supply, computer/microcomputer information processing, mobile communications data remote transmission, single-bus Integrated Temperature Gradient Detection techniques, are all used in the whole system. It realizes a real-time, ice and water information remote monitoring, which is not limited by area and weather condition in the coverage of China Mobile. It can not only satisfy the need of automatic measurement of the ice-coating thickness on electric power wires and towers, but also apply to real-time measurement of the ice thickness on harsh environment, such as forests, all kinds of field buildings, oil well plat roof on the sea and so on.The research results have been successfully applied to entries, "All-Weather Ice and Water Information Automation Monitoring System Based on the Physical Properties Differences of Air, Ice and Water" and win special Expo first prize of the eleventh "Challenge Cup" National University academic and scientific works of extra-curricular competitions.