An Efficient Structure for Parallel Cascade Control

摘要

A control structure capable of avoiding interactions between the two loops of a parallel cascade system is developed. A conventional controller is used in the inner loop and an IMC controller is inserted in the outer loop in order to reject only the effects of the perturbations that are not taken care of by the inner controller. Various possible IMC structures are compared in order to show the advantages of the proposed structure. This control scheme outperforms conventional controllers and other control structures that are designed to avoid interactions between the two loops both in the nominal case and in the presence of uncertainties, provided that the IMC controller is carefully designed. The proposed structure is shown to be even more advantageous when the primary measurements are infrequently sampled.