MIMO Robust Control for HVAC Systems

Potential improvements in heating, ventilating, and air conditioning (HVAC) system performance are investigated through the application of multiple-input-multiple-output (MIMO) robust controllers. This approach differs dramatically from today´s prevalent method of building HVAC controllers using multiple single-input-single-output control loops. A simulation model of an experimental HVAC system is used in the design and simulation testing of controllers. While simulation can be insightful, the only way to truly verify the performance provided by different HVAC controller designs is by actually using them to control an HVAC system. Thus, an experimental HVAC system was built for testing a wide range of advanced HVAC controllers. The design and testing of MIMO robust controllers provides valuable insight into potential improvements in performance, as well as constraints, associated with applying this control methodology to HVAC systems. Test results on the physical system demonstrate achievable performance gains (reductions in discharge air temperature settle time) in excess of 300%. Furthermore, these performance gains may be achieved without significant impact to current HVAC system architecture (interconnection).