This paper is concerned with the design of a simple Internal model control based PID controller (IMC-PID) for purely integrating processes with large dead time (IPD). Here, we develop an IMC-PID tuning rules by using first-order Padé approximation for time delay representation and a second-order filter is used to make the controller structure proper. Selection of the suitable value for close-loop time constant is the primary concern; because, it is the sole tuning parameter for improving the transient and steady state behavior of the process output. The close-loop time constant is computed though a simple linear relation based on the instantaneous process error. The performance of the proposed IMC-PID controller is compared with the well known model based PID tuning rules to justify its effectiveness.

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