| An aero-engine is a complicated time-varying plant with strong nonlinearity and strong coupling.In recent years,a number of methods of modeling of aero-engines have emerged,which have certain limitations.In order to describe the dynamic performance of the engine system more accurately and conduct satisfactory control design,uncertainties in aero-engine models must be taken into account.The study in this aspect is of great important both in theory and in engineering applications.This thesis establishes a switched model of aero-engines with unknown parameters based on multiple equilibrium points.Since continuous dynamics and discrete switched signals exist in a switched system,the interaction between them makes the dynamic behavior of the switched system extremely complicated.Therefore,traditional control methods usually is no longer applicable,and a new control method needs to be applied.In addition,the state of the aero-engine has better dynamic performance when approaching the safety boundary line.However,the closer to the safety boundary,the more likely it is to have safety problems such as over-temperature and over-speed.Therefore,this thesis introduces the switched mechanism into aero-engine modeling and controller design.The speed regulation and temperature protection are decomposed into multiple loops control for the two contradictions between the rapidity and safety of aero-engine.The speed tracking control problem with temperature protection for the aero-engine switched systems is investigated.Finally,the software and hardware in the loop simulation is given to verify the effectiveness.The main contributions of this thesis are as follows:Firstly,the speed tracking control and safety protection problems of the direct model reference adaptive control is investigated.By using the theory of the model reference adaptive,the switched reference model is given,and the controller of each loop are designed by decomposing rapidity and safety.By using the dwell time method,the stability problem of the error switched system is given.The switching rules is identified to guarantee the requirement of temperature protection.Effective switching between the speed tracking loop and the safety protection loop is realized,which provides a possible strategy to solve the contradictions between the rapidity and safety of engines especially for the speed tracking control problem with temperature protection for the engine switched systems.Secondly,by using indirect model reference adaptive control method,the parameter estimation value of the engine switching system are acquired and the speed tracking control problem with temperature protection is studied.The parameters of the engine switched system are identified online by using the estimator.And,in order to obtain the stability of the error switched system,an estimation error switched system is established,and an adaptive controller are designed for its subsystems based on the estimated value.Considering the speed tracking control and safety protection,the aero-engine speed tracking and temperature protection control are realized on the basis of ensuring the boundedness and convergence of the engine switched system parameter estimates.Finally,the closed-loop reference model is introduced to study the closed-loop model reference adaptive speed tracking and temperature protection control to improve the dynamic performance of the engine switched system.According to the control target design,the closed-loop reference model is designed.And then,the closed-loop error switching system is established,and the adaptive controllers are designed for its subsystems.By using the switched systems theory,a class of the switched rules is designed and some sufficient conditions are provided to guarantee the stability of the closed-loop error switched system.And the aero-engine speed tracking and temperature protection control are realized by designing the switched rules of the speed loop and the temperature protection loop controller. |
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