计及负频率影响的科里奥利质量流量计信号处理方法

New signal processing method with negative frequency contribution for Coriolis mass flowmeter

采用滑动Goertzel算法计算科里奥利质量流量计信号的相位差时,存在较长的收敛过程,其主要原因之一是忽略了负频率成分的贡献。基于DTFT递推算法,提出了一种计及负频率影响的科里奥利质量流量计信号处理方法。首先采用自适应格型陷波滤波器对科里奥利质量流量计的传感器输出信号进行滤波并求得其频率,然后采用计及负频率影响的DTFT递推算法计算两路信号之间的实时相位差,再通过频率和相位差计算出时间差,从而求得质量流量。仿真结果表明,该方法可极大缩短相位差和时间差计算的收敛过程,具有较高的计算精度,且当应用于实际的系统时不易发生数值溢出。

Because the contribution of negative frequency is neglected in the algorithm, long convergence process exists when calculating phase difference between two signals of Coriolis mass flowmeter using sliding Goertzel algorithm. A new signal processing method for Coriolis mass flowmeter is proposed, which is based on the recursive DTFT algorithm and considers the contribution of negative frequency. First, an adaptive lattice notch filter is applied tofilter the sensor output signals of Coriolis mass flowmeter and calculate the frequency. Then, the recursive DTFT algorithm with negative frequency contribution is used to calculate the real-time phase difference between the two enhanced signals. With the frequency and the phase difference obtained, the time interval of two signals is calculated and then the mass flow is derived. Simulation results show that the convergence process of phase difference and time interval calculation is largely shortened by the method. So the accuracy of phase difference and time interval calculation is improved. Furthermore, the new method is less prone to numerical overflow problem while applied to practical systems.