A joint research team from China and the United Kingdom has developed a 20 kW-class wireless charging system for new energy vehicles (NEVs) that overcomes key thermal and efficiency barriers in inductive energy transfer. Interestingly, the 20-kilowatt wireless charging system achieves an unprecedented efficiency of 98.51 percent.
The Dongguan Institute of Materials Science and Technology of the Chinese Academy of Sciences (CAS) led the research in collaboration with the CAS Institute of Physics, the City University of Hong Kong and the University of Cambridge.
Cut the cord
Self-driving electric vehicles can navigate complex roads, but their autonomy comes to a halt if they require a manual plug-in to charge. This human dependence poses a major problem for fully automated transportation. Therefore, the newly developed automated wireless charging technology aims to eliminate this limitation and enable autonomous fleets to operate and refuel without human intervention.
Common wireless charging pads usually use heavy ferrite cores to conduct magnetic fields. Ferrite works well at low power, but when you crank up the wattage to quickly charge a car, the material kicks back. It overheats, loses efficiency and stifles power density.
The researchers addressed this problem by using stress-annealed Fe-based nanocrystalline alloys with material system codesign.
“Here, we report an inductive charging system using Fe-based nanocrystalline alloys and developed through combined optimization at the material and system levels,” the team noted.
Engineers made a surprising design decision by favoring moderate magnetic permeability over maximum values to balance system performance. This strategy led to the development of a compact magnetic core tape measuring 440 mm x 330 mm and just 4 mm thick. The resulting material achieves half the profile of standard ferrite plates while handling high power densities.
98.51% efficient
To optimize the core structure, the researchers used a special stress annealing process combined with coil-aligned lamination. These techniques successfully reduced nuclear energy losses to 135 kW/m³ under test conditions of 85 kHz and 0.2 T.
According to the study, the system delivers an AC-to-AC conversion efficiency of 98.51% and a volumetric power density of 9.55 kW/L across its coils and cores. In addition, thermal stability is reliably maintained during high-performance operating cycles.
“The integration of material and electrical design facilitates the development of inductive charging systems to support autonomous vehicles and electromobility,” the study continues.
Automated driving needs automated refueling. Without contactless charging, fully autonomous robotaxi fleets remain a pipe dream.
It is tailor-made for China’s ambitious five-year plan (2026-2030) for intelligent connected vehicles, which aims for widespread commercial autonomous driving on major urban highways and expressways by 2030.
Cars are just the beginning.
The Dongguan Institute of Materials Science and Technology is already in the process of moving the prototype into commercial production. Aside from personal electric vehicles, the technology is aimed at industrial automated guided vehicles (AGVs) in factories, heavy rail transport and even low-altitude electric aircraft.
Through higher speeds, a thinner profile and lower operating temperatures, the joint Sino-British team has paved the way for a world where machines can easily recharge in the background.
The study was recently published in the journal Nature communication.
