Off-Equilibrium Linearization-Based Control of Nonlinear Time-Delay System and Application to a Turbofan Engine

Abstract

Turbofan engines exhibit pronounced nonlinearity due to component characteristics and thermal processes, necessitating linearization to connect engine control with linear control theory. Off-equilibrium linearization offers excellent transient tracking and controller performance, making it ideal for military turbofan engines with rapid acceleration and deceleration. Hardware-in-Loop (HIL) experiments are crucial for verifying controller performance, but time delays in the HIL platform can cause oscillations in state variables when using this linearization method. To address this issue, this paper introduces an off-equilibrium linearization-based control strategy. This strategy employs an off-equilibrium linearized model to approximate the nonlinear time-delay system, followed by designing an H∞ controller for the linear time-delay system. The effectiveness of this approach applied to turbofan engines, including its antidelay and robust tracking capabilities, is validated through simulations, HIL experiments, and semiphysical experiments.