Adaptive Tracking Control For The Switched Model Of The Aeroengine

The aeroengine is a complicated plant with strong nonlinearity,and the model problem is one of the keys and the difficulties for the aeroengine control.A nonlinear model of the engine is developed according to the working principle of the engine and the aerodynamic characteristics between components.Generally,the modeling process is complex,and the accurate algebraic expression of the nonlinear model is unavailable.Thus,the nonlinear model is not suitable for control design.At present,the linear model and the LPV model are widely used to describe the engine nonlinear characteristics in the aeroengine control applications.However,the linear model is limited in the whole flight envelope and the LPV model lacks a theoretical basis to guarantee the stability.Therefore,developing an engine model with simple structure to describe the nonlinear characteristics accurate in the whole envelope is significant.Due to the reasons above,a switched model is developed based on the switched property of the engine in the whole flight envelope in this thesis.Then,on the basis of this model,the relevant control methods are studied.The main contributions of this thesis are as follows.(1)The state tracking problem of the model reference adaptive control for aeroengine with multi-operating points is studied.Firstly,a switched model including a set of linear model at several selected steady-state operating points is presented.This model describes approximately engine dynamic in the whole flight envelope and considers the control objectives and the dynamic parameters between the engine stages.Meanwhile,according to the desired performance requirements of the engine,we give a switched reference model.On this basis,the adaptive controller of the subsystem is designed to ensure each individual subsystem achieving the state tracking.Finally,an error switched system is established.Then,we design a switched rule to guarantee the requirements of each subsystem dynamic performance and the stability of the error switched system.Thus,the tracking control problem of the switched model reference adaptive for engine is solved.(2)Considering the engineering practice,we separately investigate the switched model reference adaptive tracking control problem for engine with two types of disturbances.Fistly,we consider the case of the system with the unknown disturbance.The stability of the error subsystem is guaranteed with the designed subsystem adaptive controller.Then,we provide a switched law such that the subsystem can achieve the state tracking performance and the stability of the error switched system.Secondly,we study the case of the system with the external disturbance.We design a H? adaptive controller and a switched rule to solve the H? state tracking model reference adaptive control problem for engine with this external disturbance.(3)The state tracking model reference adaptive control problem for engine under the changing mach number is concerned.Fist of all,a switched model is built based on the changing mach number.The subsystem adaptive control is designed to ensure the error subsystem is stable.Then,this switched model is compared with the real nonlinear model in order to verify the accuracy of this model.Moreover,the effectiveness of the proposed method is verified by comparing the controller based on the switched model with the controller based on the real nonlinear model.