Synchronization Measurement And Control Of The Multi-Cooling System Based On Chaos Theory

The multi-cooling system is a common form of the refrigeration system. It’s mainly composed of the compressor rack, the condenser unit and multiple independent display cases. The supermarket refrigeration system is a typical multi-cooling system. Food is placed in different cases based on their different storage temperatures, these display cases share a set of compressor rack and condenser unit. The temperature in the display case is typically maintained by the hysteresis controller. These controllers are designed and operate independently, but this concept neglects cross-coupling effects. Practice has shown that in the Supermarket refrigeration system, the temperature regulation in one display case influences that in the neighboring ones. These interactions from time to time lead to a synchronous operation in the display cases, which finally causes decreased cold storage quality and increased energy consumption.At present, people pay more and more attention on the energy problem with the rapid growth of Chinese economic. At the same time new energy is developed and utilized, the effective utilization rate of energy has become an important problem. Because the refrigeration industry consumes large amounts of energy, so how to solve the synchronization in the supermarket refrigeration system and improve the effective utilization rate of energy has became an important research subject. The paper mainly studies the synchronization measurement on Kuramoto order parameter and de-synchronization on delayed feedback control. Main contends of the paper are described as follows:The working principle of the multi-cooling system and the reasons causing synchronization in the multi-cooling system are introduced; The supermarket refrigeration system is a typical multi-cooling system, the model of the supermarket refrigeration system aimed to describe the dynamic characteristics of synchronization is discussed, the model is composed of individuals models of the display cases, the suction manifold and the compressor rack; and under reasonable assumptions, the above nonlinear model is simplified into a piecewise-affine switched model.The definition, basic characteristics and decisive parameters of chaos are introduced; the stability of the system is analyzed based on the Poincare map theory; the dynamic characteristics of the system are discussed based on the bifurcation theory. We have found that when the system has a low-period orbit, there is a tendency to synchronization, when the system has a high-period orbit, even the complex chaos-like behavior, it is far away from the synchronization. The above information is a foundation of developing the de-synchronization method by chaotification of the system.The Kuramoto model and Kuramoto order parameter are introduced; the synchronization is early detected by calculating Kuramoto order parameter; several typical chaos anti-control methods are discussed, the target of de-synchronization is achieved by using delayed feedback control based on the idea of making it chaotic; the result shows that energy consumption of the system is obviously decreased after de-synchronization.