基于MSP430的高精度宽量程智能涡街流量计设计和测试

Design and Test of High Precision,Wide Range and Intelligent Vortex Flowmeter Based on MSP430

传统涡街流量计对管道环境适应性弱,量程比偏小,且易受到各种噪声的干扰,无法适用于石化、冶金等艰苦工业环境。提出一种高精度、宽量程、环境适应能力强的智能涡街流量计。硬件设计上,以内置了低功耗硬核快速傅里叶变换(FFT)乘法器的MSP430系列单片机为主控制核心,对压电式涡街传感器输出的微弱信号进行自适应带通滤波和自动增益控制放大,得到较为稳定的模拟频率信号;对模拟频率信号进行数字化采集、运算处理,得到与实际流量相关的稳定脉冲信号,以较好克服现场机械振动和电磁信号的干扰,改善涡街流量计的环境适应能力,提高系统的综合测量精度。软件设计上,以FFT算法作为辅助方法,规避高频信号段,在低流速、弱信号的情况下大大增强计量的准确性。现场测试实验结果表明:设计的涡街流量计运行稳定,相对示值误差、重复性误差均符合国家标准《涡街流量计》JJG1029—2007中1级表指标要求,在各种工业环境下的水气介质涡街流量测量中具有非常广泛的适用性。

Traditional vortex flowmeter has weak adaptability to pipeline environment,small measuring range ratio,and is easily interfered by various noises,so it cannot be applied to harsh industrial environments such as petrochemical and metallurgical environments.An intelligent vortex flowmeter with high accuracy,wide measuring range and strong environmental adaptability was proposed.In hardware design,MSP430 series single chip microcomputer with built-in low-power hard core fast Fourier transform(FFT)multiplier was used as the main control core,and the adaptive band-pass filtering and automatic gain control amplification were carried out on the weak signal output by piezoelectric vortex sensor to obtain a more stable analog frequency signal;the analog frequency signal was digitally collected and calculated to obtain a stable pulse signal related to the actual flow,so as to better overcome the interference of field mechanical vibration and electromagnetic signals,improve the environmental adaptability of the vortex flowmeter,and enhance the comprehensive measurement accuracy of the system.In software design,FFT algorithm was used as an auxiliary method to avoid high frequency signal section and greatly enhance the accuracy of measurement in the case of low flow rate and weak signal.The field test results show that the designed vortex flowmeter runs stably,and the relative indication error and repeatability error meet the standards of the first level meter in the national standard Vortex Flowmeter(JJG 1029—2007),so it has a very wide range of applicability in the measurement of water and gas medium vortex flow under various industrial environments.