Tracking-protection-recovery switching control for aero-engines.

This paper presents a novel tracking-protection-recovery switching strategy to solve the thrust tracking and safety protection multi-objective control problem for the aero-engines. The proposed switching control strategy overcomes the contradiction between the tracking performance and the safety requirement. The design procedure is with larger degree of freedom and less conservatism. The proposed switching controller can be designed in three steps. For the tracking stage, the tracking controller is designed only according to the rapidity requirement for the thrust tracking with less consideration of safety. For the protection stage, the protection controller is activated to limit the protected output in the safety region. Because of the properly designed protection controller, it is unnecessary to switch on the protection controller before the protected output reaches the safety boundary. That reduces conservatism and makes the tracking performance improved. For the recovery stage, the recovery controller, as well as the properly designed resetting law, is utilized to guarantee finite number of switches and the resulting asymptotic tracking. Because of the properly designed switch-off condition for the protection controller, the thrust tracking performance gets improved. The protected output is also successfully limited. Finally, a case study for a two-spool turbofan engine is performed to verify the effectiveness of the proposed scheme. It is also indicated that the proposed tracking-protection-recovery switching strategy can improve both safety performance and the tracking transient performance.