A Cuboid Geometry Design for MVDC Power Cables for Using in Future All Electric Wide Body Aircraft

Abstract

Designing high-power-delivery and low-system-mass electric power systems (EPS) is a major goal to achieve the next generation of electrified aircraft. As one of its major components, cables must be redesigned to obtain high-power-density and low-system-mass EPS. Among challenges in designing aircraft cables such as arc and arc tracking, partial discharges (PD), and thermal management, the latter is decisive since the thermal properties of the cable determine its maximum ampacity. The maximum permissible current of a cable depends on radiative and convective heat transfers from its surface to the ambient environment. At the cruising altitude (12.2 km) of wide-body aircraft where the air pressure is 18.8 kPa, the convective heat transfer is greatly reduced which results in a reduction in maximum permissible current. Moreover, both radiative and convective heat transfers depend on the surface area of the cable. One way to increase the heat transfers and compensate for the reduction of convective heat transfer from a limited air pressure is to change the geometry of the cable. The cuboid geometry design provides a larger contact area with the ambient environment for the same cross-section area, so it is expected that the heat transfer will increase compared to conventional cylindrical cables, and in turn, the maximum power carrying capacity of the cable will be larger. Here, the question is whether the hypothesis is true, and if so, how much improvement can be expected. The purpose of this paper is to answer these questions and, for the first time, an MVDC (5 kVdc) high power (1 kA) cuboid shape cable is designed for future AEA to increase the maximum permissible current of the cable.

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