Design Method of IMC Controllers for Unstable Cascade Processes with Time Delay
ZHANG Jing-gang;QIN Na-na;Institute of Electronic Information Engineering,Taiyuan University of Science and Technology;
A design method of internal model control(IMC) controllers for unstable cascade processes with time delay is presented. The cascade proposed structure contains two control loops, a secondary loop and a primary loop. In the secondary loop, an analytical design method is derived based on the traditional IMC, it can quickly reject the disturbance in the inner loop. In order to decouple the set-point tracking characteristic from disturbance rejection characteristic, a 2 degree of freedom(DOF) IMC structure is used in the primary loop. Then the set point tracking controller and the disturbance rejection controller can be tuned independently, which overcomes the shortage of a traditional IMC. Both theoretical analysis and simulation results demonstrate that the proposed method can reduce the number of controller effectively,meanwhile provide good performance of set-point tracking and disturbance rejection as well as robustness simultaneously.