Electric Power Systems



Introduction

The use of electric technologies in aviation is expanding, as is evident from recent designs of transport aircraft. A reason for this is that electric technologies tend to be more power efficient. An electrically operated system produces or uses only as much power as needed, thus minimizing losses and avoiding excessive power extraction from the engines. Further expected advantages are better reliability, lower maintenance and lifecycle cost.

Yet, electric technologies tend to be heavier than their hydraulic or pneumatic equivalents. On the other hand, only one instead of two or three forms of power is used on an aircraft. It is necessary to carefully consider the capabilities of electric generation and distribution, as well as to balance (manage) all power demands in order to optimize an electric system architecture.

Power electronics, such as voltage converters or motor drives, are a key technology for the more-electric aircraft. Their weight depends on the characteristics of the loads supplied by an electric system, as well as the required degree of network stability and acceptable distortion (power quality).

All these issues have to be considered carefully to realize the full potential of the more-electric aircraft. In cooperation with European aircraft and system manufacturers, the team Energy Systems is developing methods and tools based on modeling and simulation that cover a broad scope of aspects in electric power system design, analysis and optimization.

Architecture Level Design

At the stage of architecture level design, various options are examined to compare their benefits and drawbacks. Related to each architecture option, a certain amount of studies is involved, such as determining the dimensioning operating cases and loads, weight, and a preliminary safety analysis. These are repetitive and time-consuming tasks.

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 Architecture Level Design – Concept of ENADOT

To improve the efficiency of the design process, an integrated tool based on modeling and simulation is developed by the team Energy Systems. Named as the Electric Network Architecture Design Optimization Tool (ENADOT), it is capable of evaluating architecture designs w.r.t. power behavior, dimensioning loads, weight, rejected heat (cooling demands), safety and reliability. ENADOT is implemented in the object-oriented, physical modeling language Modelica. It employs a steady-state modeling approach (architecture level). Diverse automatic analysis and optimization capabilities are incorporated, so that the different aspects of architecture design are covered in a combined manner.

Design and verification of electrical components and systems

In the future aircraft design concept, the electrical power supply system will gain more attentions. In the HVDC architecture of the  “More Electric Aircraft” ( MEA), electro - mechanical actuators are supplied by a DC network. Numerous power electronic components such as DC / AC DC / DC converter are used for current regulation , which can lead to many high frequency harmonics in the electrical network . Besides the well known negative effects of high frequency harmonics such as life reduction of equipment and energy loss, unwanted mutual interference between several components  can also be caused. As result, the entire electrical network can be destabilized. Methods and tools are developed by the team Energy Systems to optimize the operation of the aircraft electrical system. The main research areas are :

  • Multi-level modeling und simulation
  • Modeling of electrical machines
  • Optimization of electrical generators
  • Network stability and power quality
  • Failure analysis
  • Virtual V&V testing or aircraft electrical systems
  • Test rig for aircraft electrical networks: The test rig is built for the validation of the new methods for network stability and power quality studies.
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  • Components of the test rig
    • Labview Real-time System for the real-time simulation of a generator
    • A DLR electric actuator
    • A Siemens electric actuator for as load
    • DC/DC Buck-converter
    • Electric loads
    • NI FPGA Platform

Selected Publications

  • Schallert, C.: Ein integriertes Entwurfswerkzeug für elektrische Bordsysteme. Deutscher Luft- und Raumfahrt Kongress, 31.08. – 02.09.10, Hamburg.
  • Schallert, C.: An integrated tool for aircraft electric power systems pre-design. International workshop on aircraft system technologies, 26. – 27.03.09, Hamburg.
  • Papers 1
  • Papers 2
     

 

 

 

 

 

 

 

 

 

 


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