The Research and Development of Particulate Mass Concentration Sensor Based on Light Scattering Method
Abstract： Rapid and accurate detection of the mass concentration particles in the running gas has a very important practical significance. The traditional filter weighing method has its limitation. This paper does the research on Light scattering method particle to detect mass concentration of population.Then, this paper introduce the actual object we made .The main tasks are as follows:
Firstly, the theoretical research and MATLAB simulation. Basing on the optical equivalent spherical particle diameter , the paper conducts the particles flux modeling formulas. So We can obtain the linear theory about mass concentration of the particles and Luminous flux .
Secondly, this paper should finish the optical structural design of sensor . This paper begins to determine the lighting source selection ,the size of the photosensitive area , the photodiode selection , the design of light trap. All this work is based on the above theoretical research and with the help of relevant literature .Last, this paper finish assembling the sensor.
Thirdly, this paper finishes a weak signal processing circuit design and makes the actual object. First, we make the model of lock-in amplifier .This paper starts to design and make the preamplifier circuit, fourth-order band pass filters, multipliers and phase locked loop demodulation circuit and a light source drive circuit. Then, this paper does some circuit simulations of above circuit.
Fourthly, experimental data processing and measuring the performance of the sensor. And this paper mainly completes the particle generator test, temperature compensation, the sensor calibration. So, this paper determines the mass concentration conversion coefficient K, the minimum measured concentration, the minimum effective concentration of the resolution, the maximum measuring range , and based on above work ,this paper does the absolute error analysis and the relative error analysis.
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Keywords：Particle matter ; Mie scattering theory ; Lock-in amplifier ; Experimental
Calibration
Classification：TP23
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目 次
摘要............................................................................................................ II 目 次........................................................................................................ V 图清单 ...................................................................................................... VII 表清单 ........................................................................................................ X 1 绪论 ....................................................................................................... 1 1.1 引言 ................................................................................................................... 1 1.2 空气中颗粒物质量浓度的测量方法 ............................................................... 2 1.3 国外先进的颗粒物检测技术 ........................................................................... 2 1.4 光散射法测量颗粒物质量浓度国内外研究现状 ........................................... 4 1.5 本文主要研究内容 ........................................................................................... 5 2 光散射颗粒物质量浓度测量理论的研究 ............................................... 7 2.1 Mie散射理论 ................................................................................................... 7 2.1.1 单球形颗粒Mie散射理论 ......................................................................... 7 2.1.2 基于单球形颗粒Mie散射理论的MATLAB仿真 ................................... 9 2.1.3 无因次参数x对单球形颗粒光强分布的影响 ........................................ 11 2.1.4 相对于折射率m对单球形颗粒散射光强分布的影响 ........................... 12 2.2 Mie散射光通量的计算 ................................................................................. 12 2.2.1 单球形颗粒的散射光通量计算 ................................................................ 12 2.2.2 颗粒群光散射光通量建模与计算 ............................................................ 13 2.3 各参数对光通量大小的影响分析 ................................................................. 15 2.3.1 F-D与采光中心角之间曲线关系 ............................................................ 16 2.3.2 F-D与采光立体角之间曲线关系 ............................................................ 16 2.3.3 颗粒物相对折射率与F-D曲线关系 ....................................................... 17 2.4 本章小结 ......................................................................................................... 18 3 颗粒物传感器的结构设计 ................................................................... 19 3.1 颗粒物浓度传感器的光学结构设计 ............................................................. 19 3.1.1 光源和透镜的选择 .................................................................................... 19 3.1.2 光阑组设计 ................................................................................................ 20 3.1.3 采光中心角大小选取 ................................................................................ 20
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3.1.4 采光立体角大小选取 ................................................................................ 21 3.1.5 光陷阱 ........................................................................................................ 22 3.1.6 光敏区大小选取 ........................................................................................ 22 3.2 传感器结构装配 ............................................................................................. 23 3.3 本章总结 ......................................................................................................... 25 4 基于锁相放大器的硬件电路设计 ........................................................ 26 4.1 电路总体设计 ................................................................................................. 26 4.2 锁相放大器基本结构及建模 ......................................................................... 27 4.2.1 锁相放大器的应用范围及其优点 ............................................................ 27 4.2.2 锁相放大器建模 ........................................................................................ 27 4.3 前置放大电路设计 ......................................................................................... 28 4.4 四阶带通滤波器设计 ..................................................................................... 29 4.5 方波乘法器设计 ............................................................................................. 31 4.6 锁相环解调电路设计与性能研究 ................................................................. 32 4.6.1 锁相环(PLL)建模 ...................................................................................... 32 4.6.2 锁相环解调电路实现方案 ........................................................................ 33 4.7 光源驱动电路设计 ......................................................................................... 38 4.8 基于ARM的信号采集微控制器设计 .......................................................... 39 4.8.1 内核基于Cortex-M3的STM32处理器 .................................................. 40 4.8.2 调零电路设计 ............................................................................................ 40 4.8.3 存储电路设计 ............................................................................................ 41 4.8.4 触摸屏电路设计 ........................................................................................ 41 4.9 本章小结 ......................................................................................................... 42 5 颗粒物质量浓度传感器的软件设计 .................................................... 43 5.1 STM32控制器软件设计 ................................................................................ 43 5.2 上位机软件设计 ............................................................................................. 44 5.2.1 数据采集和显示模块 ................................................................................ 45 5.2.2 数据存储模块 ............................................................................................ 46 5.3 本章小结 ......................................................................................................... 47 6 实验数据处理和传感器性能研究 ........................................................ 48 6.1 实验装置研究和零点处理 ............................................................................. 48 6.1.1 颗粒物发生器的研究 ................................................................................ 49
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6.1.2 传感器零点温漂的研究和温度补偿 ........................................................ 50 6.2 传感器K值测定 ............................................................................................ 53 6.3 传感器与TSI8532标准仪器测量结果对比分析 ......................................... 59 6.4 重复性测试 ..................................................................................................... 61 6.5 传感器的时域响应时间 ................................................................................. 61 6.6 传感器的性能 ................................................................................................. 62 6.7 本章总结 ......................................................................................................... 62 7 总结和展望 ......................................................................................... 63 7.1 总结 ................................................................................................................. 63 7.2 展望 ................................................................................................................. 63 参考文献 ................................................................................................... 65 作者简历 ................................................................................................... 68
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