基于DSP技术的气体浓度与流量检测电路研究

【作者】 蔡远彬；

【导师】 周鹰；

【作者基本信息】 电子科技大学 ， 光学工程， 2011， 硕士

【摘要】 本文针对谐振腔型新型氢气传感器的工作特点,设计了传感器的驱动和检测电路。在传感器几何参数固定的情况下,利用正弦信号驱动传感器,通过检测传感器的谐振频率的变化来反映传感器中氢气和空气在声学特性(声阻抗、声速)上的差异,进而确定氢气浓度。其研究内容重点包括:(1)比较目前国内外检测氢气浓度方法的原理以及其利弊。其次,研究氢气的特点尤其是其声学特性,提出了基于谐振腔型氢气传感器检测方法的可行性。同时,详细介绍了其检测原理。(2)设计了检测的硬件系统:传感器的驱动模块、信号的采集模块、DSP信号处理模块。同时,为了硬件系统的便携式,开发了由AVR单片机控制的人机交互界面。最后,设计了相应的软件(上位机软件)使得硬件检测系统更有效。(3)首先,对传感器的等效电路(LC串并电路)进行实验测试。同时,针对快速傅里叶变换(FFT)存在的运算时间和计算精度的矛盾,设计了一种基于DDS校正提高频谱分辨率的算法。实验分析证明,该算法能有效的解决运算时间和运算精度的矛盾。其次,针对实际传感器在改变不同结构条件的情况下进行模拟实验。实验表明在不同条件下谐振腔的共振频率和幅度均有明显的变化,验证检测系统的可行性。(4)针对检测硬件系统在气体流量检测中的应用,进行前期的相关检测模型、理论、MATLAB仿真及硬件系统需要改动的研究。更多还原

【Abstract】 For the characteristic of the new resonance cavity hydrogen gas sensor, the driving circuit and detection circuit for the sensor are designed in this thesis. When the sensor geometric parameters are constant, it is drived by a sinusoidal signal and the change of resonant frequency is detected to reflect the different acoustic properties sunch as acoustic impedance, acoustic velocity between hydrogen and air, and then determine the hydrogen concentration. The focus of this thesis’s research includes:(1) The principles and the advantages and disadvantages of different detections of hydrogen concentration at home and abroad are compared. The characteristics of hydrogen especially acoustic properties are studied, and a detection method based on resonance cavity hydrogen gas sensor is proposed. Meanwhile, the details of its detection theory are presented.(2) The detection hardware system is designed and the sensor driver module, signal acquisition module and DSP signal processing module are contained. At the same time, the efficient human-computer interface is developed and controled by AVR microcon -troller for a portable instrument. The corresponding software (PC software) is designed to make the detection hardware system more effective furtherly.(3) Firstly, the tests of the sensor’s equivalent circuit (LC series-parallel circut) are realized, and an algorithm improving frequency resolution based on DDS calibration is presented to resolve the conflict between operation time and calculating accuracy in Fast Fourier Transform (FFT). Experimental results show the conflict canbe effectively resolved.Secondly, the simulation experiments for the actual sensor under the different conditions are performed. It is showed that the sensor makes a significant change of amplitude and resonance frequency, which validates the feasibility of detection system.(4)For using the hardware system in the gas flow detection, the study on the model, theory and MATLAB simulation of correlation detection and hardware’s change are made.更多还原