基于示值误差拟合的电磁流量计特征系数计算方法  

Calculation Method Based on Indication Error Fitting for the Characteristic Coefficient of Electromagnetic Flowmeters

作　　者：许伟[1] 徐科军[1] 梁利平[1] 舒张平 

机构地区：[1]合肥工业大学电气与自动化工程学院,安徽合肥230009

出　　处：《自动化仪表》2017年第8期100-102,共3页Process Automation Instrumentation

摘　　要：目前,采用基于绝对误差的拟合方法计算电磁流量计仪表特征系数,会导致电磁流量计在小流速时示值误差较大,降低了准确度等级。为了反映电磁流量计本身固有的准确度等级,提出了基于示值误差的拟合方法计算仪表特征系数,充分考虑小流速点的测量误差,即以示值误差的平方和最小为驱动,使测量流速与标准流速之间的示值误差的平方和为最小。对两台不同口径的电磁流量计进行标定试验,比较两种不同方法计算出的仪表特征系数的测量效果发现,对于相同的标定数据,采用示值误差的拟合方法计算出的仪表特征系数的电磁流量计的测量准确度高于采用绝对误差拟合方法。试验结果表明,采用示值误差的拟合方法计算出的仪表特征系数减小了电磁流量计测量小流速时的示值误差,在电磁流量计的量程下限依然可以保持较高的测量准确度,能真实地反映仪表最佳的准确度等级。At present,the fitting method based on absolute error used to calculate the characteristic coefficient of electromagnetic flowmeter may result in large indication error in small flow velocity and reduce the accuracy grade. In order to reflect the inherent accuracy grade of the electromagnetic flowmeter,the fitting method based on the indication error is proposed to calculate the meter characteristic coefficient and fully consider the measurement error of small flow velocity,which regards to the minimal of the square sum of the indication error as the drive to minimize the indication error between the measured flow velocity and the standard flow velocity. The calibration tests for two of the electromagnetic flowmeters with different diameter are conducted,and the measurement effects for meter characteristic coefficient are compared. It is found that for the same calibration data,the measurement accuracy of the electromagnetic flowmeter with the characteristic coefficient calculated by the indication error fitting method is higher than that of the electromagnetic flowmeter with the characteristic coefficient calculated by the absolute error fitting method. The experimental results show that the meter characteristic coefficient calculated by the fitting method of the indication error reduces the indication error of the electromagnetic flowmeter when the measured flow rate is small. The calculation method for meter characteristic coefficient proposed makes electromagnetic flowmeter maintain a higher measurement accuracy in the lower limit of the range and truly reflect the intrinsic accuracy grade.

关 键 词：电磁流量计 绝对误差 特征系数 小流速 准确度等级 示值误差 数据拟合 

分 类 号：TH6[机械工程—机械制造及自动化] TP216[自动化与计算机技术—检测技术与自动化装置]