Studies On Excitation Control And Signal Processing Of Slurry-type Electromagnetic Flowmeter

Electromagnetic flowmeter is widely used in industrial flow measurement. But the low-frequency square-wave excitation and the lower system computing power have constrained high-precision and high-speed measurement cability of electromagnetic flowmeter, and its ability of measureing slurry and other complex fluid as well. Excitation control and enhanced system computing power become the key to improve the performance of electromagnetic flowmeter,particularly to improve the performance of slurry measurement. In the paper, by theoretical simulation, the excitation control method based on linear voltage regulator and the method based on high-low voltage power switching are proposed, and the circuit's simulation, design and experiment are conducted too. Adopting the excitation control method based on linear voltage and using DSP-chip TMS320F2812 as the core of signal processing and system control, slurry-type electromagnetic flowmeter system is developed. And, PC monitor software is designed by the Graphical User Interface of MATLAB to monitor the operation of electromagnetic flowmeter and display signal gathered real-time. Then, the signal processing method based on comb-peak filtering for the measurement of water flow and the method based on statistical analysis and signal reconstruction for the measurement of slurry flow are adopted respectively. Also, the comparing experiments of slurry measurement as well as the calibration experiments for velocity of flow simulator and water flow are conducted.The experimental results show that, the square-wave excitation control methods can broaden the frequency range of square-wave excitation widely under the premise of ensuring stable signal zero, and combing with PC monitor software, the calibration accuracy of electromagnetic flowmenter system developed is better than 0.5 for water flow as well as velocity of flow simulator, the fluctuating scale of full flow measurement for slurry is lower than 1% with a short response time in 4 seconds. Thereby, this significantly increases the measurement accuracy and speed of electromagnetic flowmeter, particularly improves the performance of electromagnetic flowmeter for slurry measurement. Hence, the study promotes the technology of domestic electromagnetic flowmeter and lays a certain foundation for its going into the international advanced level as well.