Modeling And Switching Control Of Turbofan Aero-engine

The turbofan aero-engine is an extremely complex aerodynamic plant. There exist many safety boundaries during the running process of the aero-engine. Usually, the safety boundaries mutually restrict, which makes the control synthesis much more difficult. The controller design of the aero-engine is often aimed at multiple objectives. Thus, the traditional methods are often not well applicable because it is usually hard to meet such a requirement. The object of this paper is to design suitable controllers such that both the high pressure spool speed tracking and temperature protection for high pressure turbine inlet are achieved. The switching technique provides an effective way to solve such a problem. Based on such a technique, multiple controllers and the switching laws can be designed respectively such that every desired performance index can be satisfied and the optimal performance of the whole system can be also ensured. The adoption of switching technique can in some degree solve the design problem under the mutual restriction of the safety boundaries and simplify the process of the controller design.This paper studies the modeling problem of a certain type of separate exhaust turbofan aero-engine. The model of every component for the turbofan aero-engine is established according to the engine aerothermodynamics principle. Since the above-mentioned non-linear system model is difficult to use for the control synthesis, a small deviation model (equilibrium manifold expansion model) based on the above-mentioned models is built. The switching controller is designed and simulation is implemented for such a model, respectively.For convenience of stability analysis, the continuous system model of the aero-engine is discretized into a linear parameter-vary ing model (LPV). The conditions guaranteeing the stability of the linear parameter-varying model are presented by solving a set of linear matrix inequalities (LMIs). Simulations show that the high pressure spool speed can track the reference signal satisfactorily while the temperature of high pressure turbine inlet remains in the safe region. The effectiveness of the switching controller is demonstrated by the simulations.