System Identification and Controller Development for a Small Turbojet Engine

Sinan Ekinci, Ali Turker Kutay, Oguz Uzol and Melih Yigitturk

This paper presents the results of a system identification and controller development study for a small generic turbojet engine. Custom Full Authority Digital Engine Control (FADEC) system hardware and embedded software are designed and implemented on the engine. The system also controls the automatic start-up sequence for the engine to ensure a safe and certain ignition under all-weather conditions as well as safe acceleration until the engine reaches the idle rpm. The shut-down sequence is also controlled to make sure the engine is stopped and cooled-down in a safe manner. Both of these sequences are operated in open-loop. For closed-loop feedback control operation, a dynamic mathematical model of the engine is obtained through a series of system identification tests. The developed FADEC system is used to supply the engine a pre-determined fuel flow rate schedule in open-loop. Various step and sinusoidal signals are applied to the fuel pump and the engine�s responses to these commands are recorded. Linear dynamic models are fitted to the responses to represent engine behavior at different speeds. The obtained models are then used to design feedback controllers to ensure optimum engine performance despite changing loads and environmental conditions.

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