PID-Fuzzy control of air handling units in the presence of uncertainty

Air-handling unit (AHU) is one of the most complex installations that its control is necessary for maintaining satisfactory comfort conditions in buildings with low energy utilization. In this paper, a multivariable nonlinear and minimum phase model of the AHU is considered in the presence of uncertainties. The controller design is divided into two types. The first controller type is for the linearized plant based on decoupled PID-Fuzzy and PD-type Fuzzy controllers. The second type is based on full matrix PID-Fuzzy and pole-placement controllers in which interaction effects are considered. The indoor temperature and relative humidity are controlled via manipulation of valve positions of air and cold water flow rates. Attainment of tracking goals is inspected through various desired commands of indoor temperature and relative humidity. According to the results, all of the controllers are efficient but the decoupled PD-type Fuzzy controller is the worst controller in tracking of desired commands. In comparison with other controllers, the decoupled PID-Fuzzy controller guarantees the robust performance against the model-based parametric uncertainties. In addition, using pole-placement controller leads to the less energy consumption in comparison with the other controllers.