A novel on-line auto-tuning PI controller for the superheat of evaporator with electronic expansion valve

摘要

A novel on-line auto-tuning PI control algorithm for the superheat of the evaporator is proposed in this paper. A first-order plus dead-time model is firstly employed to describe the system process, and the model parameters are obtained from the robust identification algorithm using the on-line experimental data. Then, a PI controller, whose parameters are tuned by the Ziegler-Nichols method, is designed to control the superheat at the outlet of evaporator by adjusting the opening of the electronic expansion valve. The MATLAB simulation results show the superheat can well track the change of its setting point through the effective control of the electronic expansion valve. The wide application of this controller will greatly increase the heat transfer efficiency of the evaporator.