Robust control and limit protection in aircraft gas turbine engines

Uncertainties and, in particular, large inlet distortions, affect closed-loop stability, performance, and erode surge margins of aircraft gas turbine engines. Traditional robust control techniques can be combined with robust reference governors to preserve the stability and tracking performance, while enforcing the surge margin constraints. The paper examines uncertainty modeling, the effect of inlet distortions on engine performance, and on controller architecture selection; it also illustrates the combined application of robust reference governor and H-infinity controller. Our results suggest that stability and tracking performance of the feedback loop can be maintained with robust control techniques, hence constraint handling (limit protection) represents the primary goal in dealing with the effect of inlet distortions.