What is the electric control valve? Between the input and output of the electric control valve, however, what does it matter? OLS Valve told us: the output of the electric control valve is difficult to use an accurate digital model to describe, but it can be accurately measured. For this characteristic, the stepper control does not respond directly to the input signal, but several fixed steps, according to each of the measurement result of the input command signal step-by-step approximation of the set amount. Reasonable control parameter settings, the method of the control object running smoothly follow or stability control, suitable for less demanding on the response speed of the flow or pressure. The electric control valve is usually used as an integral part of the automatic control system is used to adjust the flow rate or pressure of the gas. But the relationship between the input and output of the electric control valve is difficult to use an accurate digital model to describe. This is not only due to the nonlinearity of the output characteristic of the valve, while the flow through the valve the gas flow and the bellows seal balance adjust the mutual influence of the pressure drop before and after the valve valve cage is difficult to calculate. Flow control, for example, the traffic is only concerned with the degree of opening of the valve when the pressure in the valve before and after fixed, but in most cases, when the changes of the valve position of the valve, the valve before and after pressure will change, which when the flow gain the calculation is very difficult. In fact, due to the pressure in the valve before and after the effect of disturbance factors will fluctuate causing changes in the flow rate, flow through the valve the flow of gas and the degree of opening of the valve does not exist a one-to-one correspondence relationship. Due to the uncertainty of the mathematical model, the opening degree of the valve plate as the manipulated variable not meet the system requirements, and may even lead to accidents. Then the analytical relationship between the valve opening and flow or pressure drop is not easy, but with the measuring instrument can be easily under a degree of opening of the valve flow or pressure drop measurements.
Can be seen from the inappropriate features calculated output of the valve is easily measured, the The stepper control does not respond directly on the input signal, but several fixed steps, the step-by-step approximation of the set amount of the input signal. Flow or pressure drop of the valve in the high-pressure regulating valve cage plate is rotated one step after the first measurement, the control result of the comparison by the computer based on the measured value and the set value, to determine the direction of rotation of the Next valve plate, until the measured value and set the value of the difference is less than the predetermined error stops. Stepper control program design does not involve the analysis and solution of the mathematical model, and therefore is relatively simple, and generally can be achieved with a ladder. Two parameters need to be set, and the step size and sampling period in the program design. These two parameters greater impact on the accuracy and speed of response of the control system, set the system to control the accuracy and speed of response must be considered.
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