The demand and interest in unmanned aerial vehicle (UAV) technology is growing rapidly. Despite their significant weight and long charging times, most UAVs operate on batteries. There is a growing need for wireless charging systems for UAVs to overcome the drawbacks of batteries. Typical wireless charging systems utilize ferrites to improve power transfer efficiency, but the brittle nature of ferrites hinders their application in dynamic UAV operations.
Recently, unmanned aerial vehicle (UAV) technology, primarily used in military applications, has begun to expand its applications to the public and private sectors due to technological advancements. UAVs possess immense potential due to their operational advantages in reliability, maneuverability, and cost-effectiveness.
The application of photography or videography has led to its rapid growth in viability, and emerging applications have appeared in areas such as traffic monitoring, delivery services, forest fire monitoring, and monitoring dangerous areas or ecosystems. However, one challenging issue remains to be addressed, as most drones are limited by battery capacity and weight constraints.
Wireless power transfer (WPT) will be an alternative technology for handling the electrical power required by drones. It can increase the flight range and operating time of drones and will facilitate autonomous flight. Inductive WPT has been successfully applied to various electric vehicles over the years, including our earlier developed wireless electric buses. Inductive WPT systems typically consist of a transmitting coil (Tx coil) and a receiving coil (Rx coil), while in our electric buses, the Tx coils are arranged as segmented loops under the road surface throughout the bus route.
The principle of an inductive WPT is based on Faraday's law, where alternating current (AC) in the Tx coil generates a time-varying magnetic field. This time-varying magnetic field from the Tx coil is coupled to the Rx coil through the air, thereby generating a time-varying current in the Rx coil through the coupled magnetic field. An output voltage is then generated at the terminals of the Rx coil, where a specified DC voltage can be converted from the AC voltage at the Rx coil.
The principle of inductive WPT is well-defined, and it has been successfully applied as the primary power source in our electric buses using a custom Tx-Rx structure. Based on the same principle of Faraday's law, WPT can also be applied to drones. Ferrite is used in the practical implementation of the inductive WPT system to improve magnetic coupling. Ferrite is known to possess excellent high-frequency permeability and suitable electrical conductivity.
While ferrites are generally optimized devices for conducting magnetic fields with desired efficiency, they are not very practical for waveguide magnetic field testing (WPT) in drones. The brittle nature of ferrites hinders WPT applications in the extreme dynamic environments of drone operation. Several works have improved drone performance, but their practical properties limit their suitability as efficient ferrite magnetic materials for WPT. The soft magnetic composite material presented in this paper aims to replace ferrites and integrate inductive WPT systems into drones.
This paper investigates the application of different ferromagnetic materials in the magnetic cores of unmanned aerial vehicle (UAV) WPT (Wide-Touch Panel) systems. This comparative study is based on a newly developed soft magnetic composite material (SMC) and conventional ferrites used as cores in WPT systems. In particular, the selection of suitable ferromagnetic core materials for UAV WPT systems is discussed primarily by considering harsh environments.
