Nonlinear Control and Disturbance Decoupling of HVAC Systems Using Feedback Linearization and Backstepping With Load Estimation

A new control methodology is introduced for nonlinear and MIMO heating, ventilating and air conditioning (HVAC) systems. A full information feedback of states and disturbances is used for disturbance decoupling and model linearization purposes. Then a backstepping controller is applied to the system linearized model. It is shown that in this way, heat and moisture loads can be compensated completely if considered as measurable disturbances. For non-measurable disturbances, a stable observer is designed for estimation purpose. Simulation results show that the closed-loop system has good and fast tracking, offset-free and smooth response with high disturbance decoupling and optimal energy consuming properties in presence of time-varying loads.