Inductive charging systems empowered by stress-annealed nanocrystalline alloys with high induced magnetic anisotropy

The large-scale commercial deployment of autonomous electric vehicles requires automated charging solutions. Inductive charging provides an alternative but faces efficiency, power density, and thermal stability challenges associated with ferrite-based systems. Here, we report an inductive charging system utilizing Fe-based nanocrystalline alloys, developed through combined material and system-level optimization. While conventional approaches often target maximum permeability, our analysis indicates that moderate permeability aligns more effectively with system requirements. Through stress-annealing, an effective permeability of 2330 and a core loss of 135 kW/m³ (at 85 kHz, 0.2 T) are achieved. The material is subsequently fabricated into core bars via a coil-aligned lamination technique. This material–system co-design results in an inductive charger with an AC-AC efficiency of 98.51%, a volumetric power density of 9.55 kW/L (including coils and magnetic cores), and thermal stability during high-power operation. Integrating material and electrical design facilitates the development of inductive charging systems to support autonomous vehicles and electric mobility. The work tunes iron-based nanocrystalline alloys by stress annealing to reach moderate permeability and low loss, then uses coil-aligned laminated cores in a 20 KW inductive charger that achieves 98.51% alternating-current efficiency, high power density, and stable temperature.