Nonlinear control of a heating, ventilating, and air conditioning system with thermal load estimation

This paper presents a nonlinear controller for a heating, ventilating, and air conditioning (HVAC) system capable of maintaining comfort conditions under time varying thermal loads. The controller consist of a regulator and a disturbance rejection component designed using Lyapunov stability theory. The mitigation of the effect of thermal loads other than design loads on the system is due to an online thermal load and state estimator. The availability of the thermal load estimates allows the controller to keep comfort regardless of the thermal loads affecting the thermal space being heated or cooled. Simulation results are used to demonstrate the potential for keeping comfort and saving energy of this methodology on a variable-air-volume HVAC system operating on cooling mode.