Tuning PI controllers for integrating-non minimum phase plus delay time processes

Direct Synthesis method for disturbance rejection (DS-d) is employed to derive a PI controller for integrating process with non minimum phase and delay. The delay is approximated by first order Taylor Series approximation and the system is reduced to process model having only non minimum phase and integrator. The model order reduction is based on frequency response technique. The tuning parameter A for DS-d is calculated by using minimum integral absolute error (IAE) using golden section search method. Simulation examples are included to show effectiveness of the proposed controller. The technique proposed can perform well for load/disturbance changes.