Precise flow control method of proportional valve

Abstract

The invention discloses a precise flow control method of a proportional valve. The precise flow control method includes step 1, starting a system; step 2, initializing the system; step 3, collecting a flow value of the proportional valve and performing flow value scale conversion; step 4, comparing the flow value with a preset lower limit of flow value allowance, performing the step 6 if the flow value is smaller than the lower limit of the flow value allowance, or otherwise, performing the step 5; step 5, comparing the flow value with a preset upper limit of the flow value allowance, performing the step 6 if the flow value is larger than the upper limit of the flow value allowance, or otherwise, performing the step 3; step 6, looking up a controlled quantity-flow table according to the flow value subjected to scale conversion to acquire a corresponding controlled quantity 1, looking up the controlled quantity-flow table according to a preset value to acquire a corresponding controlled quantity 2, setting an equation that preset controlled quantity = current controlled quantity + controlled quantity 2 - controlled quantity 1, and controlling flow of the proportional valve. The precise flow control method has the advantage that table look-up correction is performed on the basis of closed-loop control, and thus, precise control can be realized.

Description

Technical field [0001] The invention relates to a flow control method, in particular to a method for accurately controlling the flow of a proportional valve. Background technique [0002] In current flow control applications, a proportional valve is usually used to control the flow, especially in the medical device industry using a proportional valve to accurately control the gas flow. The control is performed by directly outputting a control amount to control the opening degree of the proportional valve. Realized in open loop. However, in this flow control application, there is a problem of poor performance in practical applications. The reason can be easily analyzed: due to the inherent deficiencies of open-loop control, environmental factors such as: environmental temperature changes, atmospheric pressure changes, The impacts of these factors are objectively existent, and they only lie in the magnitude of the impact. To reduce their impact, a better environment must be const...

AI Technical Summary

Problems solved by technology

However, in this kind of flow control application, there is a problem of poor performance in practical applications. The reason can be easily analyzed: due to the inherent deficiencies of open-loop control, environmental factors such as: changes in ambient temperature, changes in atmospheric pressure, The influence of these factors exists objectively, and the only difference lies in the magnitude of the influence. To reduce the influence, a better environment needs to be constructed to satisfy it, but such a cost is high and sometimes even impossible to achieve.

In addition, equipment components will naturally decay with time and environmental factors during application, which is also the reason for the poor control effect

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