基于Colpitts电路非线性特性的非频率型谐振露点传感器机理研究

The project is aimed to explore a new actively controlled dew-point measurement based on nonlinear features of the Colpitts circuit. Its underlying mechanism can be summarized as: apply semiconductor refrigeration under active control of its temperature to produce condensation on the surface of quartz vibrators generated by the Colpitts circuit, resulting in huge change with nonlinear features of the Colpitts circuit. As a result, this abrupt change can be used to identify when dew points form. The project explicitly discusses nonlinear features of the Colpitts circuit by using numerical analysis of nonlinear dynamic circuits. It involves investigation into dependency between outputs of the Colpitts circuit and electrical parameters of quartz vibrators and the balance point when sudden change occurs to the circuit system, in an attempt to unveil the inherent link between condensation and circuit nonlinear features change and its connection with signals conversion. With regard to the condensation process, thermodynamics is applied to study the rule of the humidity sensitive element. Based on what has been discovered, optimization of sensor structures is produced. Time-frequency analysis is combined to yield quick signal extraction when there is sudden change of the Colpitts circuit. A double loop control is designed to consist of signal tracking for sudden change of the circuit and temperature tracking for formation of dew points on the surface of quartz vibrators as they occur under the influence of both electricity and heating. This research provides a theoretical framework and experiment conduct for actively controlled dew-point sensor design based on nonlinear features of the Colpitts circuit.

探索基于考毕兹(Colpitts)电路非线性特性的非频率型谐振露点测量方法，将被考毕兹电路激励的石英振子与半导体制冷器相结合，通过主动控温在石英振子表面产生凝露，使得考毕兹电路的非线性特性发生明显变化，利用电路的突变信号识别并测量露点。本项目将结合非线性动态电路的数值分析方法对考毕兹电路的非线性特性进行深入分析，研究考毕兹电路的输出特性与石英振子电参数之间的耦合机理和电路系统发生突变的平衡点，揭示出结露与电路非线性特性之间的内在变化机理与信号转换规律；针对湿空气作用在石英振子表层时所产生的水分凝结过程，结合热力学理论研究湿敏单元输入输出变化规律，给出传感器结构的优化模型；探索电、热双激励下的电路突变信号跟踪与石英振子表面露点温度跟踪的双闭环控制方法。通过本项目的研究将为基于考毕兹电路非线性特性的非频率型谐振露点传感器的设计提供理论依据与实验基础。

本项目结合非线性动态电路的数值分析方法对考毕兹电路的非线性特性进行深入分析，研究考毕兹电路的输出特性与石英振子电参数之间的耦合机理和电路系统发生突变的平衡点，揭示出结露与电路非线性特性之间的内在变化机理与信号转换规律；针对湿空气作用在石英振子表层时所产生的水分凝结过程，结合热力学理论研究湿敏单元输入输出变化规律，给出传感器结构的优化模型；设计了在电、热双激励下的电路突变信号跟踪与石英振子表面露点温度跟踪的双闭环控制方法，实现了高精度的露点自动跟踪测量。在18℃至5℃的露点温度范围中，系统的测量误差小于0.3℃，最小误差达到0.07℃。通过本项目的研究成功的为基于考毕兹电路非线性特性的非频率型谐振露点仪器的设计提供理论依据与实验基础。