Embedded Lightweight Squirrel-Cage Receiver Coil for Drone Misalignment-Tolerant Wireless Charging

Wireless charging systems in unmanned aerial vehicles (UAVs) should be compact, lightweight, and misalignment-tolerant. Equipment required for better performance, such as the receiver, cannot be placed outside the drone body, which would cause additional flight power resistance. To satisfy more demanding requirements, a novel squirrel-cage receiver coil embedded in the landing gear of a UAV is proposed. It avoids flight resistance while achieving a lightweight, simplified structure for the transmitter and receiver coils. In the experiments, a main circular transmitter coil with a 440mm outer diameter was used. The DC-DC efficiency was 78%-80% and the output current was 2.47±0.13 A in a 0-320 mm diameter area. The efficiency was >74% and current was 2.05±0.15 A in a 320-440 mm diameter area. The results show that the squirrel-cage receiver coils combined with a main and a small circular transmitting coil has good misalignment tolerance performance.