科氏质量流量计信号分析与处理

Signal Analysis and Processing of Coriolis Mass Flowmeter

对科氏质量流量计输出信号进行频谱分析,证实传感器的输出信号中不仅存在固有频率和白噪声,而且存在固有频率的倍频信号。目前信号检测多数采用模拟电路对信号进行滤波和过零点进行检测,将传感器输出的两路正弦信号转换为两路方波信号,利用两路方波信号的上升沿或者下降沿触发计数电路,进而得到两路信号的相位差和频率信息。利用数学工具对这种检测方法进行仿真计算,验证传感器倍频信号对测量结果的影响,因此提出一种数字滤波和检测方法。仿真和实验结果均表明,在信号分析基础上提出的检测方法,有效保证了科氏质量流量计的测量精度。

The signal of Coriolis mass flowmeter is evaluated via spectrum analysis, not only the resonant frequency and white noise but also the multifrequency of resonant frequency are existed in the output signal of flowmeter. The traditional signal process is using analogue circuit to filter the signal and measure the zero cross of the signal, the two output sine wave signals are transferred to two square wave signals, the rising edge or falling edge of the two square wave signals is utilized to trigger the counter circuit, and then the difference and frequency of the two signals are calculated by the counter. The detection method is simulated and the simulated data show that the measurement result is influenced by the multifrequency signals. As a result, a new filter and measurement method are designed. The simulation and experimental results show that the measurement accuracy is guaranteed by the method that it is brought forward on base of the signal analysis.