How Smart DC-to-DC Strategies Tackle Power-hungry Aircraft
The aviation industry is undergoing a significant shift from traditional AC Power distribution toward higher voltage DC power distribution. At the same time, the demand for power is increasing exponentially, especially as the industry moves to More Electric Aircraft (MEA) and electrical actuation replacing pneumatic and hydraulic actuation.
As the total power demand increases, traditional aircraft electrical distribution architectures become infeasibly heavy and, therefore, higher voltage DC power distribution is an essential enabler for More Electric Aircraft, irrespective of the propulsion or energy source technologies.
These trends do, however, add complexity to on-board power electronics, pushing the boundaries of the fundamental values of Size, Weight, Power, and Cost (SWAP-C) integral to modern airframe design. Combine this with the additional challenge of power conversion at altitudes from 40,000 to 45,000 feet, with the non-linear relationship between breakdown voltage and altitude, and the technology challenge becomes even more difficult.
High voltage electrical power on any vehicle enables a lower weight of conductor and with subsequent significant cost and weight savings for the aircraft harnessing. The conventional technology voltage of 115VAC line to neutral was established in 1956 on the Boeing KC135, setting the standard for almost all airliners since. The Airbus A380 used conventional 115VAC, but trade-studies were undertaken on the advantages of adopting 230VAC. The risks of new technology introduction were at that time deemed too high, so aircraft-level weight reductions of 2000kg in copper conductor were not realised. Subsequently, aircraft such as the Boeing 787 and the Airbus A350XWB have realised significant weight and cost savings by adopting higher voltage AC. A simple scaling calculation based on current ratio indicates that wiring for distribution of power would be 60% lighter at 800Vdc than the equivalent at 540Vdc, and 90% lighter than the equivalent at 270Vdc. That has weight implications measured in tons for next generation aircraft.
The rewards in terms of weight reduction are clear. The challenge is to develop HVDC power converters that maintain a small enough footprint to complement the reduction in cable weight. To achieve this, several complementary technologies need to be developed, including alternative dielectric materials, high voltage interconnections, design features for suppression of breakdown, and improved methods of cooling the power electronics within converters.
Working closely with Universities and Industry Partners, TT Electronics are pushing the boundaries of physics, design, and manufacture with the goal of developing a family of scalable building blocks to achieve quick-to-market HVDC secondary power conversion solutions to satisfy the emerging growth market of More Electric Aircraft and Urban Air Systems.