Research On Multivariable Adaptive Fuzzy Control For Cold Storage Refrigeration System

Cold storage refrigeration system is a complicated nonlinear system with MIMO, coupling, time-varying, and its refrigerating performance will be influenced by running condition and cold load. So establishing its mathematic model for control simulation and researching the multivariable intelligent control method are very necessary if want to obtain ideal effect of control quality and energy saving.The control difficulty in refrigeration system is how to remove the coupling between permaters. However, the transfer process of mass and energy in refrigeration system is too complicated to exactly express even by nonlinear mathematic model, so all of those control methods based on exact model can not obtain good control quality. Fuzzy control method is a good selection because it is not depend on exact model of controlled object. This research proposes a control method combining inverter compressor with electronic expansion valve based on multivariable stable adaptive fuzzy controller for cold storage refrigeration system.Firstly, it's established nonlinear mathematical model described by state-space for control simulation of refrigeration system. And then, Based on the theory of fuzzy control with variable universe and Lyapunov stability, It is designed a multivariable stable adaptive fuzzy controller for a class of MIMO complicated system such as refrigeration system. This adaptive fuzzy controller is based on fuzzy inference rules self-learning without needing so much expert control rules, which solves the problem of acquiring MIMO fuzzy inference rules. Under high approximation precision using fuzzy controller with variable universe, it's designed an easy-setting supervisory controller and self-adaptive law based on Lyapunov stability.The simulating results demonstrate that the controller can adapt the changes of running condition and cold load, has the characteristics of good tracking ability without overshoot, high control precision and strong robustness. So it has good applying prospect in refrigerating control area.