Foldable coil design for wireless charging of unmanned aerial vehicles

In this thesis, two different coil designs were developed for the wireless charging of unmanned aerial vehicles (UAVs). In applications requiring long operational durations, UAVs face challenges due to limited battery capacity, necessitating frequent manual battery replacements. Wireless power transfer (WPT) offers a solution to this issue, enabling reliable, efficient, and autonomous charging through wireless methods. The most suitable technique for short-range wireless charging of UAVs is inductive power transfer (IPT). This study proposes two distinct coil designs for the wireless charging of UAVs: a fixed planar design and a foldable Double D Double D (DDD) coil design. In the DDD coil design, IPT is achieved using receiver and transmitter coils positioned on the UAV's legs and the charging station, respectively. To avoid instability and additional weight, the receiver coils are lightweight and symmetrically integrated into both legs of the UAV. The design comprises two vertical receiver coils and three horizontal transmitter coils placed on the ground. In contrast, the foldable coil design incorporates three rectangular planar spiral coils: two movable edge windings and one fixed central winding. The foldable transmitter windings enhance alignment along the axis with the lowest alignment tolerance during landing, thereby improving magnetic coupling. The foldable wireless charging system for UAVs is designed to operate at a frequency of 138.1 kHz, delivering an output power of 100 W. Experimental measurements of the foldable coil design demonstrated an efficiency of up to 97.66% in aligned conditions. The vertical misalignment tolerances of both designs were independently analyzed. The foldable design achieved an efficiency greater than 85.48% for vertical misalignments up to 10 cm. Additionally, the magnetic flux density distribution of the designs was evaluated to analyze magnetic leakage.