Design of Control Laws Based on Inverted Decoupling and LMI for a Turboprop Engine

Abstract

Abstract A systematic approach of designing control laws for a turboprop engine is proposed. Firstly, the interactions between the control loops of a class of two-input two-output (TITO) plant are qualitatively analyzed. Since inverted decoupling well retains the dynamic characteristics of the original system, it is chosen to decouple the interactions so that the control loops can be divided into two single-input single-output (SISO) control loops. Then, the designed PI controller parameters for each control loop are obtained by solving linear matrix inequalities (LMIs) derived from Static Output Feedback (SOF) and regional pole placement. Considering that the main objective of turboprop engine control system is to ensure the demanded power at a constant propeller speed and component power is difficult to measure, this paper chooses fuel flow rate to control high pressure shaft speed and blade angle to control power turbine speed. Finally, this systematic approach is implemented and tested on integrated model of two-spool turboprop engine (TSTPE) on MATLAB. The simulation analysis and results of each step are presented in this paper. The simulation results show that applying inverted decoupling to decouple the interactions between the control loops of TSTPE is effective, and the designed control laws are capable of controlling fuel flow rate and blade angle of turboprop engine for high pressure shaft speed and power turbine shaft speed commands with appropriate tracking performance.