How to get a stable PID loop - Solutions - Huaqiang

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Before starting the PID auto-tuning adjustment, the entire PID control loop must work in a relatively stable state.
A stable PID means that the process variable is close to the set value, the output does not change irregularly, and the output value of the loop changes around the center of the control range.
Problems and solutions:
1. The PID output always outputs a large value and adjusts the change within this interval. cause:
. The gain (Gain) value is too high. The PID scan time is too long (for loops that respond quickly to PID)
Solution: Reduce the gain (Gain) value and / or select a shorter scan time 2. The process variable exceeds the set value a lot (overshoot is very large) Cause: Integral time may be too high Solution: Reduce integration time 3. Get a very unstable PID cause:
. If differential is used, there may be a problem with the differential parameters. No differentiation, it may be that the Gain value is too high. Solution:
. Adjust the differential parameters to the range of 0-1. The gain value is reduced according to the loop adjustment characteristic, and the minimum can be gradually increased from 0.x until the stable PID is obtained.