Hybrid control of the distributed refrigeration system

The supermarket refrigeration system typically has a distributed control structure, which neglects interactions between its subsystems. These interactions from time to time lead to a synchronization operation of the display-cases which causes an inferior control performance and increased energy consumption. The paper focuses on synchronization dynamics of the refrigeration system modeled as a piecewise-affine switched system. System behaviors are analyzed using chaos theory. The synchronization phenomenon is interpreted as a stable low-period orbit; if the system has a high-order periodic orbit or a chaotic behavior, the system is considered away from the synchronization. Therefore, the paper proposes a concept that the system may be de-synchronized by making it chaotic. A de-synchronization scheme is developed. It includes a synchronization-early-monitoring detector by calculating the maximum Lyapunov exponent and a de-synchronization controller by chaotifying the system using the time-delayed impulsive method, essentially a kind of hybrid control.