Physics / mechanism
Wireless power transfer (WPT) moves energy without galvanic contact via three dominant mechanisms: inductive coupling (near-field magnetic, <1 m, 85–95% efficiency at 100 W–22 kW in Qi/SAE J2954), magnetic resonance coupling (mid-range, 1–5 m, 70–90% efficiency, tolerant of misalignment via coupled LC resonators at matched frequencies), and far-field RF/microwave or laser-based approaches (rectenna arrays, <30% wall-to-load at useful range, but distance-independent geometry). Key parameters: coupling coefficient k, quality factor Q (kQ product governs range/efficiency tradeoff), operating frequency (6.78 MHz for AirFuel, 85–150 kHz for automotive), and thermal derating under misalignment. State of the art: GaN-based inverters push switching frequencies above 1 MHz with compact form factors; silicon carbide dominates high-power EV charging pads.
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