On-line, auto-tuning control of Electronic Expansion Valves

In this paper, the results of a research project aimed at deriving simple, high-performance, auto-tuning, robust control algorithms for evaporators controlled by means of EEVs (Electronic Expansion Valves) are reported. Control design is performed by resorting to a detailed virtual prototyping environment described in Beghi and Cecchinato (2009). The proposed control scheme consists of two nested loops. In the inner loop, the plant is connected in feedback to a PID controller. It is assumed that the structure of the process model is given but its parameters are unknown. The outer loop is composed of a parameter estimator and an adaptation algorithm that updates the parameters of the PID controller on the basis of the result of a system identification procedure. Performance of the proposed controller is evaluated in the virtual prototyping environment by means of simulations.