Evaluation of Power Conversion on Heavy Payload Tethered Hexarotors: A Strategic Approach

This research article addresses the evaluation of power conversion on heavy payload tethered hexarotors where the payloads are high and hovering times are long. Modifications were added to the power conversion unit based on operation reliability perspective. Since the objective power conversion is large comparing to existing tethered UAVs today, a strategic engineering approach was proposed and tested based on partial observations on current spikes and power thresholds of DCDC switching regulators. Research problem is such that, when UAV motors are consuming low currents, the current spikes are not the plausible cause of direct power failure. But at higher currents even small current spikes could cause power failures. Risk increase with time and situations worsen when UAVs operate under high precision flight controls. When the number of parallel converters are small this becomes a mission critical problem. As a solution, fast switching high current diodes are used at the low voltage high current output to block reverse currents, and then apply low voltage bus bar to prevent dependency issues on particular DCDC module. At the cost of a small power dissipations over diodes, the total current thresholds of UAV become higher. Experiment results shows that with the use of proposed method large number of paralleling switching regulators become possible and heavy payload flights become reliable.