Stabilisation of first-order plus dead-time unstable processes using PID controllers

New results on the robust stability of PID controllers with gain and phase margins for UFOPTD processes

“…The difficulty to solve this problem is that we cannot study the stability by directly computing the zeroes of the closed-loop characteristic equation of such a system since it is a transcendental equation, which has infinite roots. Hwang [11] solved this problem using the theory of D-partition [12]. In that work, for an UFOPTD process, the authors computed the region of proportional gain (denoted by k p ) and integral gain (denoted by k i ) for a fixed derivative gain (denoted by k d ).…”

“…To tune the parameters, the stability must be considered since such systems can easily tend to be unstable. Hence, some researchers have paid attention on determining all the feasible PID controllers for unstable processes with time delays [9][10][11]. Computing all the admissible space of the PID parameters gives a complete picture of the control of the UFOPTD processes.…”

Parameter plane synthesis of Matrix Converter fed Induction Motor over wide speed range

“…This technique is capable for coordination of parameters in parametric plane irrespective of the system order [8][9][10]. The D-partition technique is applied to locate the stability domain in controller parameters [11]. The authors in [12] presented the close loop DC drive performance based on parameter plane synthesis method.…”

Enhanced PID Controllers Design Based on Modified Smith Predictor Control for Unstable Process with Time Delay

“…Generally, PI or PID controllers are designed using a unity feedback control structure for these systems. Two-degreeof-freedom methods based on PID control are the most common methods [6][7][8][9][10][11]. Internal mode control and Smith predictor (SP) control are regarded as the most effective methods for process control and most widely used in industry but cannot be used directly for unstable process with time delay.…”