가변속 냉동시스템의 상태방정식 모델링과 최적제어

Abstract

Abstract This paper deals with precise analytical state equation modeling of a variable speed refrigeration system (VSRS)for optimum control in state space. The VSRS is described as multi-input and multi-output (MIMO) system, which hastwo controlled variables and two control inputs. First, the Navier-Stokes equation and mass flow rate were applied to eachcomponent of the basic refrigeration cycle to build a dynamic model. The dynamic model, represented by a differentialequation, was transformed into the state equation formula. Next, a full-order state observer was built to estimate all of thestate variables to compose an optimum control system. Then, an optimum controller was designed to minimize an evaluationfunction that has input energy and control error. Finally, simulations and experiments were conducted to verify the validityof the proposed modeling and designed optimum controller to regulate target temperature and superheat in a 1RT oil coolersystem. The results show that the proposed method, state equation modeling and optimum control, is efficient to ensure optimal control performance of the VSRS.