Multi-loop PI controller design with variable set-point weighting

FABRICIO GARELLI; RICARDO MANTZ; HERNÁN DE BATTISTA

Kouty nad Desnou, República Checa

Conferencia; 8th International Scientific?Technical Conference ? PROCESS CONTROL 2008; 2008

University of Pardubice

The paper proposes a new methodology to adapt the set-point weighting of multivariable two degree of freedom PID controllers. The main feature of this PID structure is that it allows independent responses of the system to disturbances and to set-point changes. For multivariable systems, it also permits the control designer to reduce the interaction among the different loops. However, a drastic reduction of the set-point weighting may lead to poor set-point tracking performance. The proposed adaptive set-point weighting enables to set the closed loop system for the desired set-point response and to adjust the weighting factor when interactions reach predefined limits. In this manner, the trade-off between individual loop tracking performances and crossed interaction amplitudes can be easily addressed. Variable structure control related concepts are used to analyze the methodology, since a discontinuous signal is used in order to adjust the weighting factor.