基于相关和Hilbert变换的科氏流量计相位差估计方法

Phase difference estimation method for Coriolis mass flowmeter based on correlation and Hilbert transform

科氏流量计相位差估计方法存在计算量较大、计算复杂、实时性和计算精度较差等问题,已不能满足复杂环境高精度流量测量领域的需求。为此,提出一种基于相关和Hilbert变换的科氏流量计相位差估计方法。首先,采用快速傅里叶变换(FFT)对传感器信号进行频率预估计,对信号是否整周期进行判断,对非整周期的信号进行数据延拓处理;然后,对任一路传感器信号进行自相关运算得到一路同频参考信号;对3路同频信号进行Hilbert变换,将3路变换后的信号与变换前信号进行相关运算,再利用三角函数公式即可求出相位差。与原有方法相比,所提方法克服了非整周期采样的影响,实时性、动态性更强,相位差估计精度更高,仿真分析与实测结果均证实了所提方法的有效性和优越性。

The phase difference estimation methods for Coriolis Mass Flowmeter are unsuitable for many high precision flow measurement areas, due to high computational load, high calculation complexity, low real-time performance, and poor accuracy. To solve these issues, a new phase difference estimation method for Coriolis mass nowmeter is proposed based on correlation and Hilbert Transform. Firstly, the signal frequency is estimated by FFT, which is used to determine the integrer period of the sampling signal, and the non- integer period sampling signals need to be extended. Then, the same frequency reference signal can be generated by using auto- correlation of original signal. Then, the Hilbert Transform is conducted to these three signals, and the correlation functions of these three signals with the transformed three signals can be computed. Finally, the formula of phase difference can be obtained by utilizing the sine functions. Compared with traditional methods, the proposed method is suitable for both integer-period and non-integer-period sampling signals, and its accuracy, real-time and dynamic performance is superior. Simulations and experiment results verify the effectiveness and superiority of the proposed method.