Model-free controller design for advanced energy-saving control of the refrigeration system

Nowadays, dual-loop control of the constant evaporation temperature and the minimum stable superheat has become one of the most advanced energy-saving control method in the refrigeration system. However, there still exist several problems. On one hand, practical superheat control with PID method usually leads to unstable output. On the other hand, the steady model is not suitable for variable load analysis. Moreover, the high-order, coupling and non-linear dynamic model of the refrigeration system makes it difficult to analysis and control. In order to better cope with these problems, in this paper, a model-free control strategy is proposed for the dual-input dual-output energy-saving control design of the refrigeration system. This proposed model-free control method doesn't need the mathematic model of the system under control and it is suitable for complex nonlinear systems. Simulation tests have been carried out and through the test results, the effectiveness of this proposed model-free control strategy has been fully illustrated.