Research On Disturbance-free Switching Fault-tolerant Control Of Aero-engine

In the research of fault-tolerant control of aeroengine,the switching system can control the controlled system by switching signal control subsystem.However,the control signal will produce buffeting at the time of subsystem switching.Buffeting is an unexpected transient performance,and the existence of chatter will reduce the stability,robustness and security of the system.Besides,sensor failure and time delay are also a very common phenomenon in the actual system operation.Their existence will not only destroy the stability of the system,but also lead to system instability.It is of practical significance to study the scrambling free switching of aeroengine under the condition of fault,delay and interference.In order to study the transient performance of aeroengine control system at the switching time,a linear state space model of 90K turbofan aeroengine is established for the total temperature of the exit of speed,fuel and high-pressure turbine.The existence of filter is verified by MATLAB programming and the filter coefficient is solved;Lyapunov function method is used to prove that the switching system meets the filtering characteristics and the level of undisturbed switching;The system structure of the healthy,failure failure and time-delay switching system is established by Simulink simulation.The buffeting amplitude values of the three switching systems at the switching time are compared.The results show that the buffeting amplitude values of the switching time are less than 0.0005,which proves that the filter can realize the disturbance free switching.On the basis of the analysis,the buffeting values of the decreasing interference,periodic interference,incremental interference and constant value interference function on the healthy switching system,the failure failure switching system and the delay switching system at the switching time are analyzed.The results show that the filter switching system can realize buffeting suppression under the condition of decreasing the interference function,periodic interference function and constant value interference function;The dynamic changes of stability and buffeting values of the switched system with time-varying delay and time-varying delay are analyzed.It is found that the magnitude of the constant delay time has an effect on the stability of the switched system,and the buffeting value of the switched system is independent of the lag time.The stability and transient performance of the three switching systems with filter health,fault and time delay are verified.The simulation results show that the switching system with filter can realize the undisturbed switching of aeroengine under six working conditions,and ensure the stability of the switching system.Then,it is verified that the switching system can realize the undisturbed switching among the health subsystem,the fault subsystem and the fault delay subsystem under the takeoff condition.