Investigating the Interoperability of Unsymmetrical Charging Coils for Unmanned Aerial Vehicles

Abstract

This paper investigates the interoperability of un-symmetrical transmitter (Tx) and receiver (Rx) coil geometries for wireless charging of unmanned aerial vehicles (UAVs). It evaluates the coupling performance of circular, double-D (DD), and bipolar (BP) coil structures under various excitation modes to identify configurations that minimize sensitivity to misalignment. The study analyses BP coils under both 0° and 180° excitation modes and DD coils in a conventional configuration. Finite element analysis (FEA) using Ansys Maxwell and experimental validation through hardware implementation were conducted to examine magnetic coupling across air gaps (10 to 100 mm) and lateral misalignments (±250 mm). The interoperability assessment identified the circular Tx-Rx coil pair as the most robust solution, achieving a nominal coupling coefficient $(k\approx 0.2)$ at a 50 mm air gap with misalignment tolerance of ±50 mm in both $x$ and $y$ directions. BP (0°) excitation mode demonstrated improved misalignment tolerance but required a reduced air gap for optimal coupling, while DD configurations showed stronger coupling along specific misalignment axes but were more sensitive to positional deviations. The findings emphasize the importance of coil geometry and excitation mode in enhancing UAV wireless charging performance. This research provides comprehensive guidelines for optimizing Tx-Rx coil interoperability, with the circular coil pair emerging as the most effective design for stable and efficient power transfer under real-world misalignment conditions.