Set-point weighted PID controllers for unstable systems

✍ Scribed by G Prashanti; M Chidambaram

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 172 KB
• Volume: 337
• Category: Article
• ISSN: 0016-0032
• DOI: 10.1016/s0016-0032(00)00017-x

✦ Synopsis

1249}1253) for selection of set-point weighting parameters for stable systems are extended to unstable "rst-order plus time-delay (FOPTD) systems. Since these methods require the real part of the dominant pole, an analytical solution is derived for calculation of dominant poles of the closed-loop system given the PID controllers settings. For PID controller settings given by DePaor and O'Malley (Int. J. Control 49 (1989) 1273}1284) and Clement and Chidambaram (Chem. Eng. Commun. 62 (1997) 63}74), the set-point weighting parameters are calculated and simple equations are given for the parameters in terms of (ratio of time delay to dominant time constant). Simulation results on an unstable FOPTD transfer function model and higher-order transfer function model show that the overshoot is signi"cantly reduced by employing the set-point weighting parameters in the PID controller. The performances of the closed-loop servo responses for all the extended methods are compared.