Design of a Wireless Power Transfer System with Long Air Gap

This paper presents the design of a multi-relay wireless power transfer (WPT) system suitable for millimeter-level extended air gaps in high-voltage environments. Feasibility is demonstrated through derivation, and a comparison of power and efficiency is conducted with systems employing different numbers of coils. The study highlights the comprehensive advantages of a five-coil system in terms of power transmission and efficiency. The coils utilize nanocrystalline magnetic cores, which are smaller and lighter than ferrite cores, effectively reducing the system's weight. Finite element electric field and magnetic field simulations confirm that the embedded system does not affect the insulation properties of insulators under high voltage. Experimental validation of the output characteristics shows that the optimal output efficiency can reach 50.9% under a 20V input.