Research On The Application Of Predictive Control Algorithm To A Mixed Absorption Refrigeration Cycle

The predictive control algorithm has been developed in the seventies of the twentieth century. Since the predictive control algorithm based on a predictive model is a kind of pre-calculated and second on-line optimization and state feed back control algorithms, it has good robust capability and can overcome model based error and the influence of the uncertainty factor such as parameters and structure etc. So it can adapt itself to complex environments well and guarantee good control performance and dynamic stability of the control systems. The predictive control algorithm has been succeeded in industry process control and brought much importance of industry process control since it was put forward.The thermodynamics model of the mixed absorption refrigeration cycle is analyzed and multivariable predictive control algorithm is introduced, and in this thesis DMC-PID serial control algorithm is presented based on that. The proposed DMC-PID algorithm can effectively overcome the dynamic lag and uncertainty of the cycle. The results of computer simulation and on-line application show that the algorithm has good anti-jamming ability and could improve dynamic characteristics of the absorption refrigeration cycle. Based on thermodynamics model and auto-control model, the PLC control system has been made by function charts, trapezium graphs and control program. The experiment results showed that the DMC-PID can reduce dead space error by 31.4 percent, peak error 23.5 percent and transit-time 26.3 percent compared to the PID control algorithm. The DMC-PID can improve dynamic stability of the control systems and has a good real-time response, and it is superior to the PID control algorithm. The DMC-PID control algorithm is to supply references to the research of auto-control system of the mixed absorption refrigeration cycle.