Research On Drive Circuit Design Technology Of Dual-frequency Electromagnetic Flowmeter

In the latter part of the oil field development, there is not only the oil-water two-phase flow, but also sand and other foreign matter in most cases, which means that eliminating the impact of sediment to flow measurement has very important significance for the development of production and resources. In the case of existing technology, to achieve domestic sediment noise elimination is difficult. Using the dual-frequency excitation technique to eliminate the noise of sediment has been a hot research at home and abroad, but at home, it still has many problems in its application in the oil application field. Based on dual-frequency excitation technique, this paper has a deeply research about the use of dual-frequency excitation of electromagnetic flow measure driver circuit.Firstly, we developed a dual-frequency excitation control method of electromagnetic flow-meters based on a CPLD, proposed a dual frequency excitation drive system, and developed a new flow control constant current source circuit. By using this method, we can easily change the excitation frequency, in order to increase the use of the instrument. The proposed drive system is simple to achieve. After simulation and experiment analysis, the system shows its good and stable operation status. The flow control constant current source circuit can ensure the whole current circuit system function constantly.Secondly, we proposed a higher precision signal processing circuit based on the characteristics of dual-frequency excitation electromagnetic flow-meter sensor output signal which is consist of power frequency and high frequency noise. This system uses a dual-frequency filter circuit to filter out frequency interference, and using high-precision controllable sampling signal can improve the driving circuit sensitivity and accuracy in response to the signal.Finally, we gave a dual-frequency excitation of electromagnetic flow-meters overall system which constructed with small diameter electromagnetic flow sensor designed by Daqing Oilfield Testing R & D center, and verified the dual-frequency excitation drive circuit system in Daqing Oilfield simulation environment, and analyze the test results table under various conditions of experimental.