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Frequency Domain-based Electrical Accumulator Unit (EAU)


OBJECTIVE: Analyze the frequency content and demand of emerging More Electric Aircraft and develop a Line Replaceable Unit capable of providing the high-frequency power requirements. The device will help source peak power demands and provide bus stabilization. DESCRIPTION: The advancement to more-electric aircraft (MEA) has resulted in an increased focus for electrically-driven utilities, including flight critical actuation. In addition to these new loads, advancements in radar systems have increased both the continuous and peak electrical power demand from the power system. For these applications, uninterruptible and clean electric power is an essential requirement. Emerging MEA use multiple energy sources to meet specific aircraft power demands under all expected flight conditions, including actuator peak and regenerative energy demands, power and thermal management system (PTMS) electrical starting demands, active electronically scanned array (AESA) radar systems, and emergency power demands. The characteristic switching dynamics of these loads create very large rate of current change (dI/dt) events. The sharp current rise implies increased frequency content of the power delivered to the load. The repeated sourcing of this high frequency content may lead to unexpected system performance, including diminished power component reliability, distribution system lifetimes, and filter network performance. The electrical accumulator unit (EAU) is a recently-developed technology designed to work in parallel with the main aircraft generator. During intervals of heavy peak current demand, the EAU sources the majority of the current to the load. Therefore, the generator is used more as a source of average current with the EAU sourcing the peaks. An alternative approach is sought in for this research. A frequency-domain approach to designing an EAU will include the device sourcing the highest frequency components of the current, with the main aircraft generator sourcing the lower frequency current. The goal of this program will be to determine the frequency bandwidth performance desired, and build a Line Replaceable Unit (LRU) that sources the required current. Key to the success will be advanced power electronic topologies and controls as well as advanced energy storage devices. In addition, frequency domain EAU could provide simplified means of integrating prognostics and health management (PHM) algorithms into the power system. Innovative ideas are sought to understand the frequency content and demand of emerging MEA, and to develop a LRU capable of providing these high-frequency current requirements. PHASE I: Demonstrate the feasibility of frequency-domain-based EAU to meet the requirements above. Define the conceptual design and predict the performance of the proposed design through analysis, preliminary modeling, simulation and/or small-scale testing. The proposed concept should be scalable and flexible to support various mission applications. PHASE II: Develop the detailed design and fabricate a prototypical device or hardware demonstration to be tested in a laboratory environment. Models and/or simulations should be validated by demonstrations which fully capture the relevant physics. A clear definition of failure modes would be expected as well as the ability to meet required operational lifetimes. PHASE III: This technology may have application in future commercial and military aircraft. Therefore, a production program will identify a potential transition platform and will develop necessary detail specifications for the completed LRU. REFERENCES: 1. INVENT Modeling, Simulation, Analysis and Optimization; AIAA-2010-287. 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, Orlando, Florida, January 4-7, 2010. 2. Integrated Aircraft Electrical Power System Modeling and Simulation Analysis; 2010-01-1804: Power Systems Conference, November 2010, Fort Worth, TX, USA, Session: Modeling, Simulation, Analysis & Control.
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