Stabilization region of PD controller for unstable first order process with time delay

Time delays affect considerably the performance of the process. Moreover the stabilizing regions of the controller parameters can be difficult to compute. This work provides the stability conditions for unstable first order plus time delay (UFOPTD) systems when a PD controller is used. Also, the parametric stabilization region is obtained by means of an analysis of the characteristic quasipolynomial. The results presented in this work show that a derivative action at the controller minimizes the effects of the time-delay achieving the stabilization of UFOPTD systems with large time-delay, in contrast with a process considering controller without derivative action. The behavior of the control strategy is illustrated with some numerical examples.