IMC Based Design of PI Controller for Real Time Pressure Process

Abstract: The objective of the work is to maintain the pressure in the closed loop at desired set value. The pressurized tank has the features of nonlinearity, sluggishness by tuning conventional PI methods. This paper focus on implementation of internal mode control (IMC) to obtain an optimal PI control setting for pressure process. System identification of the process is done by process reaction curve method. To improve the robustness, internal model control method (IMC) is employed in tuning the PI controller and is applied to the First Order plus Time-Delay (FOPTD) model. Here delay is approximated with First Order plus Pade Approximation. At first, a Proportional Integral (PI) controller based on IMC-PI setting is designed and the results are compared with Ziegler Nichols (ZN) controller settings. The robustness of the controllers are endorsed by imposing both servo and regulatory disturbances. The simulation results confirm that IMC-PI controller has improved dynamic performance on disturbance rejection.

Keywords: IMC, Ziegler Nichols, PI controller, Pressure process.