Induction Generator Based More Electric Architectures for Commercial Transport Aircraft

Abstract

In the trend toward more electric aircraft, optimizing the performance of the new electrical power system in terms of reliability, fault-tolerance, size, weight, e ffciency and cost is quite a challenging task, in which the type of the generator has great impact on the overall performance of the system. This dissertation explores and evaluates the option of using an induction generator for the distributed electrical power system of commercial transport more electric aircraft. In this dissertation, induction generator based electrical power generation and management system architectures are developed for both the main engine generation system and auxiliary power unit system. The application of induction generator in the proposed systems improves the system power density compared to synchronous generator based systems, and avoids the excessive faulty current issue caused by permanent magnet (PM) generators. In the main engine generation system, an induction generator based AC/DC hybrid electric power generation system under twin-shaft twin-generator concept is proposed. The proposed AC/DC hybrid generation architecture supplies constant voltage variable frequency power directly from the generator winding terminals, and enables load sharing between the two engine shafts. Control schemes are developed to regulate the AC load voltage and coordinate DC power generation between the two generators. The feasibility of operation of the proposed system is demonstrated by both computer simulation and hardware-in-the-loop real-time emulation. An auxiliary power unit (APU) that allows the regenerative power from the actuators to be absorbed by the turbine shaft of the APU is proposed. An open-end winding induction starter/generator is used to provide direct power flow path from the electro-hydrostatic actuators (EHAs) and/or electro-magnetic actuators (EMAs) to the power source, and to create a separate electric actuation bus without significant additional hardware requirement. A closed-loop control scheme for regulating both main DC bus and actuation DC bus voltages in aircraft emergency power mode is developed and verified by simulation in MATLAB/Simulink. A modular back-up power link unit for re-confi gurable fault-tolerant actuation system architecture is also proposed to provide additional power supply path for the flight safety critical actuator loads in the proposed auxiliary power unit based regenerative power management strategy. A closed-loop control scheme for extracting constant and steady power flow from the primary power source through the modular back-up power link unit is developed and verified by simulation in MATLAB/Simulink. The proposed more electric architectures in this dissertation provide solutions for electri fication development of aircraft systems in terms of enhancing the electric power generation capacity of the aircraft, reducing the hardware requirement of the electric power generation and distribution system, managing the high peak and regenerative power flow from the EHA/EMAs, and enhancing the reliability and availability of the flight safety critical actuation system and the regenerative power management system.