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With the diversity of mission capability and the associated requirement for more advanced technologies, designing modern unmanned aerial vehicle (UAV) systems is an especially challenging task. In particular, the increasing reliance on the electrical power system for delivering key aircraft functions, both electrical and mechanical, requires that a systems-approach be employed in their development. A key factor in this process is the use of modeling and simulation to inform upon critical design choices made. However, effective systems-level simulation of complex UAV power systems presents many challenges, which must be addressed to maximize the value of such methods. This paper presents the initial stages of a power system design process for a medium altitude long endurance (MALE) UAV focusing particularly on the development of three full candidate architecture models and associated technologies.

This paper analyses the behaviour of a highly-capacitive DC UAV network under fault conditions. Through simulation, the nature of overvoltage transients caused by the redistribution of stored energy following the clearance of a fault is illustrated. It is found that clearance of fault currents at or around their peak magnitude can result in substantial quantities of inductive energy being redirected into the smaller load capacitors, causing severe overvoltages across these loads. Recommendations for a protection strategy are given on the basis of the results presented, with consideration given to the use of surge arrestors to provide additional overvoltage protection to sensitive loads.

Increasingly complex and challenging mission requirements for Unmanned Aerial Vehicles (UAVs) may in the future place demands on the vehicle electrical system. Direct current and high-frequency alternating current have been proposed as alternatives to conventional AC approaches in manned aircraft which may contribute to meeting these requirements. The paper reviews the advantages and disadvantages a number of power distribution options across a range of metrics likely to be of interest to UAV designers and operators including factors such as weight, fault management and electrical losses. Important technical challenges in the application of these technologies are identified.