Research On Nonlinear Modeling And Control Of Aeroengine

Most control systems in the aerospace industry primarily use linear techniques for analysis and design.This linear design approach does not maximize engine performance.Aviation researchers have been exploring new nonlinear design and analysis methods in the analysis and design of engine control systems.The application of the nonlinear control method can effectively reduce the time and cost involved in the development of the engine control law,and has a good potential in improving the performance,reliability and safety of the engine.Sliding mode control is a control method with strong robustness and strong anti-interference ability,which is very suitable for the analysis and design of aero-engine control systems.This paper takes DGEN380 small turbofan engine as the research object,mainly studies the application of aeroengine modeling and nonlinear sliding mode control in the design of its control law.In the modeling section,different forms of engine models were built from the perspective of control engineering.In the control law design part,the stability of the system is guaranteed theoretically,and the performance of the designed controller is verified by simulation.In order to obtain a linear model at the relevant steady-state operating point.Firstly,based on the engine's own design parameters and component characteristics,the variable-ratio thermal calculation method is used to establish the steady-state cyclic model and dynamic cycle model of the engine using Matlab/Simulink simulation platform.Then,using the dynamic response model of the dynamic cycle model at the relevant steady-state operating point,the linear model is extracted based on the combination of the perturbation method and the fitting method.On the basis of the linear model,the general nonlinear term is introduced to modify the reference linear model,the working range of the model is broadened,and a simplified nonlinear model is established.This nonlinear model is the basis for the design of subsequent control laws.At the control theory level,the matrix exponential bounds are analyzed and the relationship between the matrix exponential norm and the matrix measure is given.Taking a kind of nonlinear model as the research object,the Dini upper right derivative is introduced,and a sliding function design method is proposed based on the comparison principle.A small turbofan engine sliding mode regulator is designed,and the sliding mode motion phase is designed based on the comparison principle.The approaching motion phase is designed based on the generalized Gronwall-Bellman lemma,which ensures that the system state variable makes the sliding mode motion index stable in t he sliding mode attracting region when the sliding mode arrives.The designed regulator was simulated using Matlab/Simulink.The simulation results show that for a certain range of disturbances,the system can be exponentially stabilized in equilibrium,and the engine speed can be adjusted near the expected operating point.It provides an effective idea for the analysis and design of the steady-state control law of small turbofan engines.The acceleration control law of small turbofan engine is designed based on nonlinear model.The generalized Gronwall-Bellman lemma is introduced in the design of sliding mode controller parameters,and the theoretical constraint formula of tracking error norm is given.The tracking error norm boundary can be adjusted by the selection of the control law parameters.The above acceleration control law was simulated by Matlab/Simulink.The simulation results show that the system can track the speed switching command in time and realize the acceleration control based on the nonlinear model.It provides an effective idea for the research of acceleration control of small turbofan engines.