便携式低频锁相放大器的研制及其红外CO气体检测应用

发布时间：2018-09-03 09:27

【摘要】：本论文选题来源于国家科技支撑计划“煤矿用红外CO检测仪(传感器)的研发”。由于红外气体检测法具有灵敏度高、性价比高、高选择性等优势,目前受到了国内外气体检测领域科研人员的普遍关注。锁相放大技术是检测微弱红外传感信号的关键技术之一,它能从较强的背景噪声中提取出有用信号,对研制红外气体传感器并改善其性能具有重要的意义。鉴于此,本论文研制了一种便携式双通道低频锁相放大器,应用于红外一氧化碳气体检测中。在分析了红外气体检测技术和锁相放大技术的国内外研究动态之后,本论文首先介绍了红外气体检测系统的相关原理,包括分子红外吸收光谱原理和锁相放大原理。接着,利用Simulink软件仿真平台建立了仿真实验系统,证实了本论文设计方案的可行性。在此基础上,给出了双通道低频锁相放大器的软硬件设计方案。通过功能验证性实验和一氧化碳气体检测实验,逐一测试了所研制的低频锁相放大器的各项技术指标。首先,开展了双通道低频锁相放大器的功能验证性实验。结果显示:它能提取的最小标准信号幅度为1m V;不断改变移相角度,当相位差越大时,相对移相误差越小,结果都小于0.2%。利用配备的体积分数为0—1000ppm的一氧化碳标准气体,开展了气体检测实验。结果显示:系统的检测下限为10ppm;与理论测量结果对比,相对测量误差小于15%;在一氧化碳气体浓度为0ppm时,实际检测到的气体浓度在-5.2ppm—6.2ppm之间有较小幅度的波动;波动幅度在实际气体检测过程的允许范围内。计算了系统的阿伦方差,预测系统的检测下限为1.19ppm。考虑静态配气时气体在气室中扩散的时间,系统的响应时间约为58—62s。通过开展的实验,验证了研制的锁相放大器的功能,已经达到了红外气体检测领域对提取微弱信号的要求。本论文研制的双通道低频锁相放大器,结构简单,性价比高,易于嵌入,在红外气体传感器的研制和微弱传感信号处理方面具有较好的应用前景。
[Abstract]:This thesis is based on the National Science and Technology support Program, Research and Development of Infrared CO detector (Sensor) for Coal Mine. Due to the advantages of high sensitivity, high performance-to-price ratio and high selectivity, infrared gas detection method has been widely concerned by researchers in the field of gas detection at home and abroad. Phase-locked amplification is one of the key techniques for detecting weak infrared sensing signals. It can extract useful signals from strong background noise, which is of great significance to the development of infrared gas sensors and the improvement of their performance. In view of this, a portable dual channel low frequency phase-locked amplifier is developed, which is applied to the detection of infrared carbon monoxide gas. After analyzing the research trends of infrared gas detection technology and phase-locked amplification technology at home and abroad, this paper firstly introduces the related principles of infrared gas detection system, including the principle of molecular infrared absorption spectrum and the principle of phase-locked amplification. Then, the simulation experiment system is established by using the Simulink software simulation platform, which proves the feasibility of the design of this paper. On the basis of this, the hardware and software design of two-channel low-frequency phase-locked amplifier is presented. Through the functional verification experiment and the carbon monoxide gas detection experiment, each technical index of the low-frequency phase-locked amplifier is tested one by one. First of all, the functional verification experiment of two-channel low-frequency phase-locked amplifier is carried out. The results show that the minimum standard signal amplitude is 1m V, and when the phase shift angle is changed continuously, the relative phase shift error is smaller when the phase difference is larger, and the results are less than 0.2. Gas detection experiments were carried out using carbon monoxide standard gas equipped with volume fraction of 0-1000ppm. The results show that the detection limit of the system is 10 ppm, the relative measurement error is less than 15, when the concentration of carbon monoxide is 0ppm, the detected gas concentration fluctuates slightly between -5.2 ppm-6.2 ppm. The fluctuation is within the allowable range of the actual gas detection process. The Aron variance of the system is calculated and the detection limit of the predicted system is 1.19 ppm. The response time of the system is about 58-62s considering the diffusion time of the gas in the gas chamber. Through the experiments, the function of the phase-locked amplifier has been verified, and the requirement of extracting weak signal in the field of infrared gas detection has been met. The dual-channel low-frequency phase-locked amplifier developed in this paper has the advantages of simple structure, high performance-to-price ratio and easy embedding. It has a good application prospect in the development of infrared gas sensor and the signal processing of weak sensor.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN722

【参考文献】