A Free-Positioning IPT System via Reconfigurable Coil Array Transmitter for Unmanned Aerial Vehicle Applications

The special structure, limited payload, and large range misalignments are three major impediments to the adoption of inductive power transfer (IPT) technology for unmanned aerial vehicle (UAV) unattended recharging applications. This article proposes a free-positioning IPT system to achieve reliable power transfer within large-scale horizontal offset and arbitrary 2-D rotation. Specifically, the novel magnetic structure employs a coil array transmitter and two perpendicular air-cored receiving coils. The transmitter generates a uniform rotating magnetic field with the cooperation of coil structure and its optimized excitation current vector, and the receivers based on cross-coupling mode utilize horizontal flux to establish strong coupling, by which the receivers are characterized by simple structure and lightweight. Moreover, a reconfigurable circuit topology that allows the array coils to be flexibly enabled according to the landing position of the UAV is designed and modeled. Finally, an experimental prototype is established to validate the proposal. The system can deliver 438 W with a dc-dc efficiency of 89%, and especially the variation of the output voltage is within ±8.7% during various landing positions and directions, which lays the foundation for UAV available free wireless charging in a wide range of 2-D space.