高抗干扰智能型涡街流量计的研究

【作者】 徐国梁；

【导师】 宋开臣；

【作者基本信息】 浙江大学 ， 机械电子工程， 2003， 硕士

【摘要】 涡街流量计是基于卡门涡街原理而设计的一种流量计，由于它具有其他流量计不可兼得的优点，自二十世纪七十年代以来得到了迅速的发展，据有关资料显示，现在日本、欧美等发达国家使用涡街流量计的比例大幅上升，已广泛应用于各个领域，将在未来流量仪表中占主导地位。但是现有的涡街流量计还存在着抗干扰性能差，流量计量下限高的不足，本文就这一问题进行研究。第一章阐述了流量计量技术的现状与发展，介绍了涡街流量计的工作原理，优缺点和研究现状，提出了提高抗干扰性的技术路线。第二章介绍了涡街流量计的组成，确定了在本课题中采用三角柱旋涡发生体和采用压电晶体作为应力检测传感器，提出了创新的悬浮差动式流量传感器结构，分析了它抗干扰的工作原理，并取得了良好的实验结果。第三章阐述了现在使用的涡街流量信号处理方法的不足之处，确定了采用谱分析法处理涡街流量信号。分析了涡街流量信号的特点，设计了增益自适应差动电荷放大器并介绍了它的工作原理。第四章选择周期图法实现功率谱分析，采用优化了的基4算法实现快速傅里叶变换，并阐述了在单片机上的实现。用实验证实了本课题所设计的涡街流量计具有很高的抗干扰性和大的量程比。第五章阐述了利用现代先进的低功耗技术，实现了整个仪表系统的低功耗，这就使涡街流量计可以使用电池供电，工作在不适合于市电供电的场合。第六章阐述了涡街流量计利用单片机完成各种显示、控制及通信等功能，实现流量计的高度智能化。最后总结整个设计，并提出了进一步研究的内容。本文的创新之处在于采用悬浮差动式涡街流量传感器消弱了环境干扰，得到了幅值和频率相等，相位相差180°的差动信号；采用增益自适应差动电荷放大器消除了同向干扰，并输出接近A／D转换器满量程的信号；采用低功耗单片机实现了流量信号的功率谱分析，设计出了低功耗的智能涡街流量计。更多还原

【Abstract】 Vortex flowmeter is designed on the basis of Karman vortex street principle. Because of excelling others in some aspects, it develops speedily from 1970’s. Relevant data indicates that the proportion of the use of vortex flowmeter increases considerably in developed countries, such as Japan, European and American countries in recent years and it is widely applied to various fields.Vortex flowmeter will play a leading role in all kinds of flowmeters in the future.But existing vortex flowmeter has its own disadvantage.Its noise immunity is poor and its lower limit of measuring range is high.This thesis will research into this problem.In chapter one, the thesis expounds the recent developments in flow measuring, and describes the operational principle, advantages and disadvantages of the vortex flowmeter , and the current research on it. Technical proposal is also given in this chapter.In chapter two, describes the component of the vortex flowmeter , and determines to use triangular prism as vortex generator and piezocrystal as stress detecting sensor. A novel type of vortex sensor with suspending differential structure is brought forward . Then this thesis analyzes its operational principle . The experiment result is ideal.In chapter three, describes the limitation of the current method in vortex signal processing , determines to use spectral analysis technology for signal processing . Analyzes the characteristics of vortex signal , designs a differential charge amplifier with gain adaptive function, and analyzes its operational principle.In chapter four, selects periodogram realizes the power spectrum analysis , take advantage of Radix-4 algorithm to calculate FFT ,and describes the realization in MCU .The vortex flowmeter designed in this project has excellent noise immunity and wide measuring range ratio.In chapter five,describes the low-power realization by use of modern low-power technology.So the vortex flowmeter can be supplied by dry battery and applied in the zone where there isn’t industrial electrical source .In chapter six, describes the vortex flowmeter realizes all kinds of controlling displaying and communication function. The vortex flowmeter is highlyintelligent.At last ,summarized the total thesis and introduced some theories that need more researches.The innovation in this thesis is listed below:1) Attenuate the noise from circumstance and get the differential signal with the same intensity and frequency with 180° phase difference by use of the suspending differential vortex sensor;2) Eliminate the noise with the same direction and output the signal in the full range of the A/D converter by use of the gain adaptive charge amplifier;3) Realize the power spectrum analysis for the flow signal based on a low power MCU and design a smart vortex flowmeter with low power consumption.更多还原