Subsystem Interaction Analysis in Power Distribution Systems of Next Generation Airlifters

Subsystem interaction in a simplified power distribution system of a next generation transport aircraft is addressed. Detailed analysis of interaction between an ElectroMechanical Actuator (EMA) connected to the DC bus of the power distribution system in a next generation transport aircraft with the bus regulator is presented. The classical impedance ratio criterion is used to determine local stability around an equilibrium point of each interface by observing the impedance characteristics of the source and load subsystems. Critical parameters that determine the local stability of the integrated system are identified. The loss of stability under large disturbances is presented to motivate the use of nonlinear stability analysis methods. Preliminary results of nonlinear stability analysis are presented. Introduction The research reported in this paper is concerned with the analysis of subsystem integration in power distribution systems of next generation transport aircraft. It is projected that in future aircraft, all power, except propulsion, will be distributed and processed electrically. In other words, electrical power will be utilized for driving aircraft subsystems currently powered by hydraulic, pneumatic or mechanical means including utility and flight control actuation, environmental control system, lubrication and fuel pumps, and numerous other utility functions. These concepts are embraced by what is known as the “More Electric Aircraft (MEA)” initiative. The MEA emphasizes the utilization of electrical power as opposed to hydraulic, pneumatic, and mechanical power for optimizing aircraft performance and life cycle cost. Increasing use of electric power is seen as direction of technological opportunity for aircraft power systems based on rapidly evolving technology advancements in power electronics, fault tolerant electrical power distribution systems and electrically driven primary flight control actuator systems. The aircraft power distribution system plays a central role in the development of concepts of “Power-By-Wire” and “More Electric Aircraft”. The MEA will need a highly reliable, fault tolerant, autonomously controlled electrical power system to deliver high quality power from the sources to the load [1]. Baseline Power System Architecture The proposed power distribution system is built around a 270V DC distribution bus. The typical