Optimization of Transmitting Coils Based on Uniform Magnetic Field for Unmanned Aerial Vehicle Wireless Charging System

The operational flexibility of unmanned aerial vehicles (UAVs) can be considerably improved by wireless charging without manual intervention in battery charging. To ensure the stability of power receipt, the free-position wireless charging system of UAVs should be designed with urgency. In this article, a numerical definition of a uniform magnetic field and its criteria are presented. Furthermore, two methods, the valley-filling method (VFM) and peak-clipping method (PCM), are introduced to modulate the magnetic flux based on a uniform magnetic field. The correctness of the structures proposed to promote misalignment tolerance has been confirmed by simulations and experiments. The results show that the misalignment tolerance achieved with the employment of the PCM is better than that of other methods, which could keep the transmission efficiency stable when the UAV is horizontally offset.