Aero-engine Modeling And Optimization Based On Switched LPV Model

As the power source of aircraft,aero-engine has always been an important research object in the design of engine control system.The performance of aero-engines has a great influence on the maneuverability and rapidity of aircraft.Therefore,how to design an optimal control algorithm to make the engine give full play to its potential without adding or modifying the airframe hardware and improve the flight quality of the aircraft has become a research focus in the aviation field.In this paper,a research on the modeling and optimization control of aero-engines has been carried out.The main contents include the following three parts:The first part is the establishment of aero-engine switched LPV model.Based on the turbofan engine model provided by a research institute,combined with the switching theory and LPV model theory,an aero-engine switched LPV model suitable for full flight envelope is established in this paper.Firstly,based on the operation data of the engine under a single operating condition,the small deviation state model of aero-engine is established by using the least square method and linear fitting method.On this basis,the LPV model is established by the matrix pseudo inverse method.Finally,a switched LPV model with three subsystems is formed by changing the working conditions.In the second part,the problem of unconstrained aero-engine optimization control is studied,which realizes the pursuit of speed and economy in the speed adjustment control of aero-engines.In the switched LPV system,the design of control input and switching time are coupled with each other,which makes the optimization problem of the aero-engine very complicated.In order to overcome this problem,two-step method is used to optimize the control of aero-engine system for the first time.In the first step,the optimal control input and the derivatives of the objective function to the switching time are obtained;In the second step,the gradient information of the objective function is used to solve the optimal switching time.The two-step method successfully solves the coupling problem of two optimization variables which are to be solved and realizes the innovation of extending the optimization algorithm suitable for non-parametric system to parametric system.Finally,numerical simulation and hardware-in-the-loop experiments verify the effectiveness of the proposed optimal control method.In the third part,considering the limitation of actual aero-engine fuel flow control valve,the optimization control problem of aero-engine with control input constrained is studied.By using the parametric method,the original constrained optimization problem is transformed into a new nonlinear programming problem,which reduces the amount of calculation and shortens the optimization time.Finally,the sequential quadratic programming algorithm is used to solve the nonlinear programming problem,and the simulation results verify the effectiveness of the proposed optimization method.