Aircraft Electric Power Systems and Architectures

In early stage of the aircraft history, aircraft is driven by mechanical, electrical, hydraulic and pneumatic hybrid systems. An the end of 1970’s, the idea of using electricity as dominant power source emerged and during this period the concept of More Electric Aircraft was proposed. The first commercial aircraft “Fly by Wire” (FBW)was introduced by Airbus with A320 series in 1980’s. The FBW technology can reduce the weight and volume of aircraft by replacing part of the mechanical and hydro-mechanical systems into electrical systems. In FBW system, power electrical systems generally use 115V with fixed frequency at 400Hz AC for high power onboard equipment and 28V DC for low power onboard equipment. However, some onboard systems like flight control actuation, landing gear, de-icing device and engine starter/generator are still driven by hydraulic, pneumatic and mechanical hybrid systems which are inefficiency and heavy. These defects foreshadow the wider implementation of electric power system in aircraft.

In order to remedy these defects and make flights much safer, reliable and environmental friendly, the “Power by Wire” technology emerges as the times require. In PBW technology, most of the inefficient, heavy hydraulic systems were eliminated and replaced by electrical systems which have relatively higher efficiency, stronger fault-tolerant ability and lower weight. Therefore, the aircraft EPS capacity needs to sprint higher to meet the electrical equipment’s requirements. For example, the electrical capacity of Boeing 787 has increased to 1MW during a normal flight. Apparently, compared with conventional EPS, more advanced EPS is needed to achieve high availability, stability, efficiency and low weight, volume in MEA. Besides, less engine noise, emissions and fuel burn can be realized in MEA.