Wireless Power Transfer System for Multiple Drones In-Flight Charging Applications Under Wide Charging Tolerance with Constant Charging Current

The wireless power transfer (WPT) for drones

in-flight charging is one solution for extend operation time.

However, the WPT for drones fluctuates owing to the varying

mutual inductance and changes in the distance between the

transmitter coil and the receiver coil during flight. This paper

presents a single-transmitter, multiple-receiver, wireless in-

flight charging system designed to extend the operational

duration of drones. The control method leverages bifurcation

phenomena to track the bifurcation frequency under various

coupling-coefficient conditions. To validate the proposed

method, a 470 W WPT system prototype was constructed for

an in-flight survey drone. The system supports an extended-

range power transfer at a maximum air gap of 150 mm. The

experimental results demonstrate that the WPT system can

achieve up to 82% efficiency, while maintaining a constant

receiver current.