Conventional heating, ventilating, and air conditioning (HVAC) systems have traditionally used the temperature and the humidity ratio as the quantitative indices of comfort in a room. Recently, the carbon dioxide (CO 2 ) concentration has also been recognized as having an important contribution to room comfort. This paper presents the modeling of an augmented HVAC system including CO 2 concentration, and its control strategies. Because the proposed augmented HVAC system is multi-input multi-output (MIMO) and has no relative degree problem, the dynamic extension algorithm can be employed; then, a feedback linearization technique is applied. A linear-quadratic regulator (LQR) is designed to optimize control performance and to stabilize the proposed HVAC system. Simulation results are provided to validate the proposed system model, as well as its linearized control system.
This paper describes the procedure for improving performance of PID controller based on fuzzy gain scheduling and a simple procedure to get parameters of a PI-PD controller from parameters of a PID controller. A PID controller based on fuzzy gain scheduling is first constructed, and then convert PID gains into PI-PD gains. Simulation results demonstrate that better performance can be achieved in comparison with Ziegler-Nichols controllers.
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