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Download DIGITAL PRESSURE CONTROLLER
Transcript
2.5.5 PID CONTROL The outer loop pressure controller is a form of PID control executed every 100 milliseconds (10 times per second). The pressure is controlled to an exponential decay curve. V = p * ( S − A) + i * ∫ ( S − A)dt + d * d ( S − A) dt S = Set-point A = Actual V = Control Output p,i,d = Control Coefficients pressure Figures 2–3 and 2-4 show typical Control mode operation. Pressure in percent of full scale is plotted versus time to show the change in pressure as the instrument steps from one control point to the next. 0 10 20 30 40 50 60 Time - seconds pressure FIGURE 2–3 PRESSURE CONTROL NORMAL MODE 0 10 20 30 40 50 60 Time - seconds FIGURE 2–4 PRESSURE CONTROL FAST MODE 2-9 THEORY OF OPERATION
