Abstract: Since compression refrigeration system has problems of delay, coupling and external disturbance, an improved Smith predictive decoupling control based on disturbance observer has been proposed. First, the disturbance observer is used to observe overall disturbances of the system in the conventional Smith predictive control structure. The time-delay element is linearized by first-order Pade model. Then a diagonal matrix is applied to decouple the compression refrigeration system. Finally, the tuning of the controller parameter is realized based on the minimization of ITAE criterion, and the robust stability of the whole control system is discussed. Through the simulation, the proposed method can provide a better decoupling, better robustness and immunity for the compression refrigeration system. Moreover, it saves about 0.6% energy.

Key words: compression refrigeration system, Smith predictive control, time delay, disturbance observer (DOB), robustness, decoupling