基于FPGA的锁相放大器在多组分气体检测中的应用研究

发布时间：2018-02-17 05:38

本文关键词： FPGA 锁相放大器相关检测多组分　出处：《西南科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：目前,分析变压器绝缘油中溶解的多组分气体含量是对变压器进行故障诊断的主要方法,传统的变压器绝缘油中气体检测方法存在检测精度低、灵活性低、受环境影响严重等缺点,己经不能满足当前电网安全发展的需要。光声光谱技术具有选择性好、灵敏度高、分辨率高以及无接触测量等优点,成为能够快速在线检测分析的有效方法之一。光声光谱气体检测中的光声信号十分微弱,需要运用锁相放大器对该信号进行提取。本文针对光声光谱气体检测设计一款基于FPGA的锁相放大器用于提取与气体浓度相关的光声信号。论文对锁相放大技术的相关理论进行深入阐述,包括:自相关检测技术,互相关检测技术,相敏检波原理以及锁相放大器的原理。在理论分析的基础上,设计的锁相放大器电路主要包括:信号前置放大电路、带通滤波电路、A/D转换电路、相关检测电路以及数字低通滤波电路。在对多组分气体光声光谱检测理论研究基础上将设计的数字锁相放大器应用于气体检测中。使用外腔可调谐激光器作为光源,通过流量控制器配制不同浓度比例的3种混合气体,使用锁相放大器提取了6组不同气体浓度比例的混合气体光声信号,系统对C2H2、CO2、CO的极限灵敏度分别为0.4ppm、398ppm、384ppm,并具有良好的线性度和稳定性。研究结果表明设计的锁相放大器能够准确的提取出光声信号,在光声光谱多组分气体检测领域具有良好的应用前景。
[Abstract]:At present, the analysis of dissolved multicomponent gas content in transformer insulation oil is the main method for fault diagnosis of transformer. The traditional gas detection method for transformer insulation oil has low detection accuracy and flexibility. Being seriously affected by the environment, it can not meet the needs of the current security development of the power grid. Photoacoustic spectroscopy has the advantages of good selectivity, high sensitivity, high resolution and contactless measurement. It has become one of the effective methods for fast on-line detection and analysis. The photoacoustic signal in photoacoustic spectrum gas detection is very weak. In this paper, a phase-locked amplifier based on FPGA is designed to extract the photoacoustic signal related to gas concentration. Related theories are elaborated in depth, Including: autocorrelation detection technology, cross-correlation detection technology, phase-sensitive detection principle and the principle of phase-locked amplifier. On the basis of theoretical analysis, the design of phase-locked amplifier circuit mainly includes: signal preamplifier circuit, Band-pass filter circuit A / R D conversion circuit, Correlation detection circuit and digital low-pass filter circuit. Based on the study of the theory of multicomponent photoacoustic spectrum detection, the designed digital phase-locked amplifier is used in gas detection. The tunable external cavity laser is used as the light source, and the external cavity tunable laser is used as the light source. Three kinds of mixed gases with different concentration ratio were prepared by flow controller. Six groups of mixed gas photoacoustic signals with different gas concentration ratios were extracted by phase-locked amplifier. The limit sensitivity of the system to C _ 2H _ 2C _ 2CO _ 2CO _ 2CO _ 2CO _ 2CO _ 2CO _ 2CO _ 2CO _ 2CO _ 2C _ 2H _ 2C _ 2C _ 2CO _ 2CO _ 2 CO _ 2CO _ 2CO _ 2 CO _ 2CO _ 2 CO _ 2CO _ 2 CO _ 2CO _ 2 CO _ 2CO _ 2. It has a good application prospect in the field of multicomponent gas detection by photoacoustic spectroscopy.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN791;TN722

【共引文献】