MagSafe for cars: 20 kW wireless charging with 98.5% efficiency

Revolution in electric vehicle charging: wireless system reaches 98.5% efficiency

Chinese and British scientists have unveiled an innovative 20 kW wireless charging system for electric cars that can overcome key thermal and energy barriers, achieving an unprecedented efficiency of 98.5%. This development could remove limitations for autonomous vehicles, allowing them to charge without human intervention.

Overcoming the limitations of traditional technologies

Existing wireless charging systems often use bulky ferrite cores. While ferrite is effective at low power levels, its performance drops significantly during fast charging: the material overheats, loses efficiency, and limits power density.

Researchers from the Dongguan Institute of Materials and Technology at the Chinese Academy of Sciences (CAS), in collaboration with the CAS Institute of Physics, City University of Hong Kong, and the University of Cambridge, found a solution to this problem. They replaced ferrite with nanocrystalline iron-based alloys that underwent thermal treatment under tension. By applying co-design methods for both the material and the system, the engineers achieved a balance between maximum magnetic permeability and optimal performance.

Innovative materials and their advantages

The new system uses a compact magnetic core strip measuring 440 mm by 330 mm and just 4 mm thick. This material, thinner than standard ferrite plates, can withstand significantly higher power densities. To optimize the core structure, the researchers applied specialized stress annealing and sheet-oriented lamination.

These technological solutions made it possible to minimize core energy losses to 135 kW/m³ at a frequency of 85 kHz and a magnetic field intensity of 0.2 T. As a result, the system demonstrates an AC-to-AC conversion efficiency of 98.51% and a volumetric power density of 9.55 kW/L. Another important advantage is stable thermal performance during high-power operation.

The future of autonomous electric transport

The development is part of China’s ambitious 5-year plan for autonomous vehicles, which calls for the widespread deployment of such systems on key highways by 2030. The Dongguan Institute is already working on commercializing the technology, which is aimed not only at passenger electric cars but also at industrial vehicles.

The research results were published in the prestigious scientific journal Nature.