Robust Hybrid Model Reference Adaptive Control for a Variable Speed Refrigeration System

This paper aimed to design a hybrid model reference adaptive controller (H-MRAC) that would be robust to model parameter uncertainty and disturbances to achieve high precision control of variable speed refrigeration system (VSRS). The designed H-MRAC was based on the modified MIT rule with control performance that strictly followed command values by a parameter that could minimize specific error functions. The designed H-MRAC was found to have robust control performance based on simulation and experiments of disturbance application and model parameter fluctuations for VSRS. When control performance of the designed H-MRAC was compared with that of an existing PI-only controller, it was confirmed that the designed H-MRAC had a faster settling time, fewer undershoots, and fewer steady-state errors for more precise and robust control. This is due to the advantage that the parameter used in the control of H-MRAC is automatically updated without relying on characteristic parameters of the model.