数字科氏质量流量计闭环系统及信号解算

Novel closed loop system and output signal processing of digital Coriolis mass flowmeter

在科氏质量流量计测量系统设计中,提出一种数字式信号处理、解算的全新设计思路.采用高速并行模拟数字转换电路(AD)将传感器输出的信号完整采样,借助数字信号处理芯片(DSP,DigitalSignalProcessor)强大运算能力对信号进行深入的分析与处理;利用信号处理方法对信号进行实时滤波处理并精确计算两路信号的相位差,进而解算出流体的质量流量和密度,辅以单片机和现场可编程器件(FPGA,FieldProgrammableGateArray)实现系统的控制、显示与通讯;提出谐振电路的数字式闭环设计新思想,利用数字电路及其信号处理方法实现传统的闭环增益控制(AGC,AutoGainControl).实验结果表明:该系统有效提高了测量系统的零点稳定性和测量精度.

In the processing of designing Coriolis mass flow measurement system, the novel digital method for processing the signals and calculating the results was introduced. The high performance parallel analog to digital converter (A/D) was utilized to sample the whole signals of the sensor. The sample data were deeply analyzed and processed by the high performance floating point DSP (digital signal processor). The classical signal processing method was used to filter the sample data and calculate the phase difference of the two signals, and that the mass flow and density of the liquid were calculated. The system was controlled and the output results were displayed and transferred by the single chip processor and the FPGA (field programmable gate array). Furthermore, the novel digital closed loop was brought forward in the closed loop resonant circuit, the digital circuits and digital signal processing methods were used to realize the traditional AGC (auto gain control) in the closed loop circuit. The experimental results show that the offset and the precision of the system are improved.