基于频谱细化算法的超声多普勒流量计设计

Design of ultrasonic Doppler flowmeter based on spectrum refinement algorithm

流量计作为一种计量传感器设备,是水务信息化综合系统的重要组成部分,其数据精度直接影响系统计量结果。本文基于频谱细化的方法设计了高精度超声多普勒流量计,该流量计采用低功耗单片机(MCU)作为主控芯片,产生频率可配置的中高频脉冲信号,经功率放大电路后驱动由大功率金属氧化物半导体场效应管(MOSFET)组成的超声波发射电路。设计了回波信号提取电路,实现回波信号的放大、噪声滤除、频差信号提取等功能。采用复调制ZOOM FFT频谱细化算法进行频谱分析,显著提高了频率分辨率和频移计算精度。经实验测试,在低流速(0.19 m/s)、中流速(0.5 m/s)和高流速(0.984 m/s)状态下,流量计测量误差分别为5.161%、2.248%和1.985%。

As a kind of measurement sensor equipment,flowmeter is an important part of water information integrated system,and its data precision directly affects the measurement results of the system.In this paper,a high-precision ultrasonic Doppler flowmeter is designed based on the method of spectrum refinement.The flowmeter uses lowpower consumption MCU as the main control chip to generate a medium and high-frequency pulse signal with configurable frequency,which is driven by the power amplifier circuit and the ultrasonic transmitting circuit composed of high-power MOSFET.The echo signal extraction circuit is designed to realize the echo signal amplification,noise filtering,frequency difference signal extraction and other functions.The frequency resolution and precision of frequency shift calculation accuracy are significantly improved by using multiple modulation Zoom FFT spectrum refinement algorithm for spectral analysis.The experimental results show that the measurement errors of the flowmeter are 5.161%,2.248% and 1.985% at low flow rate(0.19 m/s),medium flow rate(0.5 m/s)and high flow rate(0.984 m/s),respectively.