PID regulator with overshoot inhibition - has threshold trigger switching to prevent overshoot and steady state error

摘要

A temp. regulator with PID control action includes a threshold switching stage to limit overshoot. PID control action is built into the regulator to increase speed of response and to eliminate steady state error. With such action a sudden change in demand can result in the output temp. overshooting to an unacceptable value. The reference (Usoll) is compared (5) with the actual temperature (Uist) and the difference monitored (6) against a threshold value (Ug). If the acceptable overshoot is exceeded a trigger stage (4) is actuated to block the system summing junction (5) and limit the regulator action (3) on the process (2). A timing device (7) monitors the period of the threshold excess and triggers a memory (8) to control the duration of the blocking action.