Analytical design of decoupling control for variable-air-volume air-conditioning system

Variable-air-volume (VAV) air-conditioning system has the feature of multi-variable, intense coupling and nonlinear. The coupling may directly affect the property and the stability of VAV system. In this paper, a theoretical model of VAV air-conditioning system by combining the theoretical analysis with the data analysis of experiment is established, which is the four input-output transfer function matrix. Based on the model, a new analytical design method of decoupling controller matrix is proposed in terms of the standard internal model control structure for VAV air-conditioning system. Its advantage is that absolute decoupling for the nominal responses of system outputs can be implemented, and moreover, the controller parameters can be tuned on-line in a monotonous manner to cope with the plant unmodelled dynamics, so that significant decoupling regulation can be achieved. The simulation curves of the decoupling control system show the availability of the method.