Double-feedback gas flow sensor

Abstract

The invention discloses a double-feedback gas flow sensor which comprises a gas flow probe, a differential amplification circuit, a conditioning circuit, a compensation circuit, a controller and a power amplification circuit. The controller is used for outputting two paths of PWM waves to the power amplification circuit, then the magnitude of feedback currents are adjusted and controlled, the differential amplification circuit is not directly used for current feedback, a corresponding control algorithm is set in the controller to output proper feedback quantity, the shortcomings that analog circuit feedback quantity is too large or too small, multi-time feedback is caused, and response speed is slow are overcome, quick balance of bridge can be well achieved, and the dynamic property of the sensor is greatly improved. Meanwhile, volume flow rate is corrected in real time according to gas pressure in a pipeline, accordingly, an accurate gas volume flow value under an actual working condition is obtained, measuring errors caused by air pressure changing are removed, and the accuracy requirement on a volume flow rate meter of industrial production measuring is met.

Description

Technical field [0001] The invention belongs to the technical field of gas flow sensing, and specifically relates to a dual feedback gas flow sensor. Background technique [0002] At present, gas flow measurement methods can be divided into four categories according to the measurement principle, namely differential pressure flow meters, velocity flow meters, positive displacement flow meters and mass flow meters. According to the output type of gas flow, it can be simply divided into gas volume flow meter and gas mass flow meter. Since the volume of gas is a function of temperature and pressure, and is affected by the temperature and pressure of the medium, the measurement accuracy of gas volume flow is often not high; and the quality of gas does not change with time, temperature, and pressure, so the gas mass flow rate The measurement result is more accurate. However, in some practical applications, high-precision gas volume flow is often required. [0003] Thermal gas mass flo...

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Problems solved by technology

[0006] Aiming at the above-mentioned technical problems existing in the prior art, the present invention provides a double-feedback gas flow sensor, which obtains the volume flow rate of gas through the measurement method of gas mass flow rate, and obtains high precision under actual working conditions according to the gas pressure correction in the pipeline. The volume flow rate value, using a micro-processing unit in the feedback loop to avoid the shortcomings of a single differential analog circuit that is susceptible to external interference and slow response speed, and an additional feedback loop is added to increase the voltage of the temperature compensation component during the bridge balance process and improve the sensor Excellent dynamic performance, high measurement accuracy

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