IMC Based Control System Design of PID Cascaded Filter

An analytical method for the design of PID controller cascaded with the second order lead-lag filter is proposed for the various types of time-delay processes. The proposed design method is based on the IMC-PID method to give a desired closed-loop response. The process dead time is approximated by using the appropriate Fade expansion to convert the ideal feedback controller to the proposed PIDmiddotfilter structure with little loss of accuracy. The resulting PIDmiddotfilter controller compensates the dominant process poles and zeros efficiently and gives a drastic performance improvement in closed-loop performance. The simulation results show the superior performance of the proposed PIDmiddotfilter controller over the conventional PID controllers. The guideline for the closed-loop time constant lambda has also been suggested for the FOPDT and SOPDT models