Control strategy for electric starter generators embedded in gas turbine engine for aerospace applications

The market for integrated power systems for Unmanned Air Vehicles (UAVs) is developing quickly [1]. Due to space constraints a practical solution for UAVs is to employ electric-starter generators (ESG) embedded in gas turbine engines to facilitate electric engine crank, assist the engine to the desired idle speed and generate power to drive the onboard auxiliaries [2]. However, the traditional sensors that provide accurate knowledge of the machine rotor position to facilitate precise control of the ESG cannot be used because of the adverse operating conditions. This paper describes the challenges of embedding and coupling a position sensorless based permanent magnet ESG directly onto a single shaft of a small, low-cost, gas turbine engine. The complete hardware and control architecture was tested on an experimental test rig using a dynamometer to mimic the gas turbine engine. Following the testing in laboratory, the system was commissioned into the gas turbine Small Electric Engine Demonstrator (SEED). The paper highlights the importance of verification and validation stages when considering a significant technical programme.