Hierarchical Hybrid Control for Innovative Air-conditioning Equipment

This paper describes the control system for innovative air-conditioning equipment, in particular an air treatment unit. The most important characteristic of the equipment is to be “friend of the environment”, in the sense that it does not use environmentally aggressive refrigerating fluids. Other main characteristic is associated with the complexity of its control, due to the large number of input and output variables and the necessity to maintain several concurrent processes, ranging from the processes associated with equipment security to processes associated with normal functions, as heating and cooling, including processes associated with the cleaning of the air, using humidifiers. For the system development, Microsoft Visual C++ was used as code integration platform, enabling merging of results obtained from LabWindows/CVI for virtual instrumentation and generation the application synoptic, with other results obtained from Statemate Magnum (used as a Statecharts based development system). The used control methods rely on Statechart models (which are adequate for modelling of systems controlled by discrete events) using continuous variables associated to some states of the system (needed for some actuators of the equipment). The simulation and validation of the model were major tasks that were taken prior to the implementation of the system. Key-words: Statecharts; Reactive systems; Embedded systems; Automatic code generation; Air-conditioning