A Refinement Procedure for PID Controllers

Proportional-Integral-Derivative (PID) controllers are still extensively used in industrial systems. In the literature, many publications can be found considering PID controller design for processes with resonances, integrators and unstable transfer functions. However, due to structural limitations of PID controllers, generally, a good closed-loop performance cannot be achieved with a PID, for controlling the aforementioned processes, and usually a step response with a high overshoot and oscillation is obtained. PI-PD controllers provide very satisfactory closed-loop performances in the case of controlling processes with resonances, integrators and unstable transfer functions. This paper introduces a simple approach to get parameters of a PI-PD controller from parameters of a PID controller so that a good closed-loop system performance can be realized. Extensive simulation examples are given to illustrate the value of the approach proposed.