ENERGY CONVERSION SYSTEMS FOR HIGH ALTITUDE PSEUDO-SATELLITES

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-07-2 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 42, 223-230 pp, DOI: 10.5593/sgem2017/42/S17.029

ABSTRACT

In this paper are presented some studies concerning energy conversion systems for High Altitude Pseudo-Satellites (HAPS).
In the first part of the paper, a state-of-the-art in the field of energy conversion systems on board of high altitude UAVs together with the identification of future trends in electrical propulsion of aircrafts are shown.
The interfacing between the fuel cells and the bus, as well as the bus voltage adjustment is made via the DC to DC converters. Simple type boost converters are lighter, but have a lower gain. On the ground, they require large heat radiators, but at higher altitudes due to low external temperatures the radiators sizes can be lowered substantially. Resonant converters perform much better gain, but contain transformers, which are heavy and thus increases the weight of the aircraft, and thus the energy propulsion required. It is necessary to carry out a study to identify optimal energy balance from the point of view of the entire aircraft.
There are also performed critical analyses of few possible constructive solutions, their advantages and disadvantages and some estimations concerning dimensioning of these conversion systems.

Keywords: pseudo-satellites, fuel cell, batteries, photovoltaic cells, non-isolated DC to DC converters; isolated converters