| The demand for liquid flow rate control and more and more precise production requirements in the industry have promoted the development of electromagnetic liquid flow meters.In recent years,many scholars have made achievements in accuracy improvement,cost control and intelligence improvement,but they are still lacking.Comprehensive and systematic comprehensive research,which leads to a significant increase in cost while accuracy is improved,too much attention to power consumption brings measurement accuracy to a halt,accuracy and cost are controlled within a reasonable range,but the intelligence of the flowmeter.No mention of it.Therefore,it is necessary to develop an electromagnetic liquid flowmeter intelligent converter under comprehensive consideration of various aspects such as accuracy improvement,cost control and intelligence improvement.The electromagnetic liquid flowmeter uses the principle of Faraday electromagnetic induction.When the charged liquid flows in the controllable magnetic field of the sensor,the charged particles in the liquid will be affected by the Lorentz force and hit the sensor plates on both sides of the sensor.,When the electric field force and Lorentz force given to the charged particles by the electric field between the two plates reach a balance,the induced voltage value output by the sensor is stable and changes with the flow velocity.In order to better complete this subject,a water tank circulating water experiment platform is designed.Taking into account the improvement of measurement accuracy,this subject needs to design a signal processing circuit for processing the small voltage output by the sensor.Through filtering experiments and band-pass circuit verification,a signal processing that can amplify the flow rate voltage signal in the passband by 4800 times and has a good filtering effect is finally obtained.Circuit.Another important factor to improve accuracy is the choice of excitation frequency and excitation mode.This topic determines that the excitation frequency is 6.25 Hz by comparing the waveforms of the flow velocity voltage signal with excitation frequencies of 100 Hz,25Hz,12.5Hz,and 6.25 Hz.Comparing square wave excitation,three-state wave excitation,sine wave excitation and triangle wave excitation,the waveform of the flow velocity voltage signal and the data collected by ADC confirm that the excitation mode is square wave.Taking into account the performance and cost of the excitation circuit,three different circuits that can generate an excitation square wave are compared,and it is finally determined that the current source composed of an operational amplifier and an excitation circuit composed of an H bridge are selected for this topic.In this project,many intelligent modules are designed to improve the intelligence of electromagnetic liquid flowmeters,including SMS sending module,RS-485 module,flow calculation module and so on.The realization of these modules relies on the software design of a main function and three interrupt functions,which can ensure the intelligence of the instrument without affecting the real-time and accuracy of its flow rate measurement.In addition,in order to improve the accuracy of meter flow measurement,the software design also includes a simple one-dimensional median filter algorithm combined with a one-dimensional average filter algorithm to process the data collected by the ADC.The application of this algorithm has improved.The measurement accuracy will not increase the cost.In the end,this subject was successfully developed to measure the liquid flow rate in the range of 0.001m/s to 2.5m/s,the average error of the measurement was within ±0.35%,the repeatability was not higher than 0.4%,and the accuracy requirements of 0.35 were met,and the cost of the device was less than 500 Yuan,an electromagnetic liquid flow meter intelligent converter with many intelligent functions. |
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