基于CPLD的涡街流量计仪表系数非线性修正  

Nonlinear Modified Method on K-factor of Vortex Flowmeter Based on CPLD

作　　者：郑丹丹[1] 张涛[1] 

机构地区：[1]天津大学电气与自动化工程学院天津市过程检测与控制重点实验室,天津300072

出　　处：《化工自动化及仪表》2010年第3期58-61,65,共5页Control and Instruments in Chemical Industry

基　　金：国家高技术研究发展计划项目(2007AA04Z180);天津市科技发展计划项目(06YFGZGX00900)

摘　　要：涡街流量计输出的频率信号能够在较宽流量范围内保持良好的重复性,但其仪表系数只能在较窄的范围内保持恒定,从而制约了其测量范围。本文提出一种基于CPLD的仪表系数非线性修正方法,即采用三次样条插值法对流量-仪表系数曲线进行逼近,通过优化CPLD查找表实现了对仪表系数的非线性修正。实验表明,该方法在保证精度的前提下可以有效地扩展量程。对于存在仪表系数非线性问题的其他流量仪表也同样适用,易于推广。There is a good repeatability of output frequency signals of vortex flowmeter in a wide flowrate range. However, the K-factor remains a constant in a narrow scope, which restraints the measurement range of vortex flowmeter. A nonlinear modified method of K-factor based on CPLD was given. The spline interpolation method was adopted to approximate relation curve of flowrate and K-factor. The modified algorithm was realized by optimization on look-up-table which was embedded in CPLD. Through experiments, it is indicated that the measurement range is expanded within accuracy level by vortex flowmeter with nonlinear modified method. Furthermore, this method is ap- plicable in any other flowmeters which have the same nonlinear problem of K-factor.

关 键 词：涡街流量计 CPLD 仪表系数 非线性修正 

分 类 号：TQ056[化学工程]