How to tune PID controller
As we know the PID controller is composed of 3 components namely:
1.Component proportional constant Kp
2. Component Integrator with constant Ki
3. Differentiator with a constant component Kd
In the PID control tuning, we mean that set the value of KI, Kp and Kd to obtain the most optimum value. There is a several way to tune PID controller such of:
1. Zieger Nichols
2. Cohen-Con
3. IAE-ISE
The loop performance must fall between two extremes:
1. First, the loop must respond to a change in set point and to disturbances. That is, an error, or difference in the process and the set point, must eventually result in the manipulation of the output so that the error is eliminated. If the gain, reset, and derivative of the loop are turned to zero there will be no response.
2. Second extreme :
The other extreme is instability. An unstable loop will oscillate without bound. A set point change will cause the loop to start oscillating, and the oscillations will continue. At worst, the oscillations will grow (or diverge).
Proper tuning of a loop will allow the loop to respond to set point changes and disturbances without causing instability.
Rule of thumb for informal methode PID Tuning : optimum decay ratio :1/4 quarter wave decay.
There is no single combination of tuning parameters that will provide quarter wave decay. If the gain is increased and the reset rate decreased by the correct amount the decay ratio will remain the same.
you can reach more detailed explanation in this file ..................or this
