A nonlinear switching control strategy of regulation and safety protection for aero-engines based on the equilibrium manifold expansion model

Abstract

This article proposes a nonlinear switching control strategy to solve the regulation control problem with safety constraint for aero-engines based on the equilibrium manifold expansion model. That is a kind of nonlinear model with satisfactory accuracy. The design procedure includes design of sub-controllers such as the nonlinear high-pressure spool speed tracking controller, high pressure turbine outlet temperature safety protection controller and the nonlinear dynamic feedback recovery controller. Also, switching law and dynamic controller state reset law are properly designed. Under the proposed strategy, system trajectory starting from temperature safety boundary will never return to the safety boundary. The designed reset law ensures a smooth switching from protection mode to recovery mode. Switch-off moment of the protection controller can be arbitrarily selected according to the tracking performance requirement. Freedom degree of selection is enlarged. The sub-controllers corresponding to objectives of regulation and safety protection are designed separately with more freedom degree and less conservatism. The effectiveness and the robustness of the proposed strategy are verified through a case study for a two-spool turbofan engine.