Wireless Power Transfer System for Lightweight Unmanned Aerial Vehicle in Free-Azimuth Flight

In some special work scenarios, unmanned aerial vehicles (UAVs) are un land or need to hover for a long time. Inflight wireless power transfer (WPT) technology improves convenience and extends operating hours. However, there will inevitably be some offset during in-flight WPT. Realization of in-flight WPT for UAVs in any position will greatly improve the availability. At the same time, in order to minimize the impact on the work of the UAVs and to increase the applicability, the WPT system needs to be specially designed in order to meet requirements such as lightweight. A novel WPT system for the above requirements is proposed in this paper. A rotating time-varying magnetic field is generated by designed coils and control of current phase. Wireless power can be received when the UAV is hovering at any azimuth around the transmitter coil. The system operates at 6.78 MHz for a lighter weight and a longer transfer distance. Class-EF converters which designed for the current requirement are used. A 50 W experimental prototype is developed to verify the proposed WPT system.