Research On Fault Tolerant Control For Aeroengine Gas Path Component

This paper focuses on the research of fault tolerant control for a turbofan engine in the entire flight envelope, which accommodates performance loss caused by gas path component faults. To restore thrust and component stall margins, the closed-loop control system is realized online which includes fault diagnosis and performance accommodations.Based on a volume dynamic aero-engine component level model, the construction of state variable models and the method of improving linear model accuracy are discussed. The state variables are determined on the thermodynamic characteristics of engine chambers, and various state groups are obtained with different classification criterions that help to analyze their influence on linear model accuracy. A Linear Parameter Varying(LPV) model is built up on the basis of linear models in various conditions from idle to maximum state, and high model precision is achieved.A Quantum behaved Particle Swarm Optimization-based(QPSO) Linear Quadratic Gaussian with Loop Transfer Recovery(LQG/LTR) control method is proposed for the aero-engine system, in order to solve the problem of choosing weight parameters in classical trial-and-error way. Adjustable parameter q is optimized automatically according to singular value curves of target loop and actual loop. Then design parameters are acquired. This improved controller design reduces blindness of the traditional method and has good control performance.Considering the fact that gas-path component faults could be caused by foreign stuff inspiration, mechanical fracturing, or component efficiency reduction to a certain level, high rotor system faults are ranked by efficiency and flow factors. Based on design points selected from the flight envelope, QPSO algorithm is applied to obtain engine inputs adjustments in the large fault magnitude while approximate functions are used to get the inputs in medium and small fault cases. The off-line performance accommodation interpolation schedules are designed.Extend Kalman Filter-based(EKF) fault diagnosis module and non-linear transformation module that transforms input adjustments to reference adjustments are designed to construct the aero-engine closed-loop fault tolerant control system, which accommodates performance for high rotor components online. Simulations indicate that the fault tolerant control could reduce thrust and stall margins loss effectively.