Wireless Charging for Electric Vehicles: The Impact of Air Gap Distance and Coil Alignment on Power Transfer Efficiency

This study examines inductive power transfer (IPT)-based wireless power transfer (WPT) for electric vehicle (EV) charging, focusing on static WPT (SWPT). Experimental analysis evaluated air gap variations (20–200 mm) and lateral misalignment (-100 mm to 100 mm) on coupling coefficient (K), coil inductance (L1, L2), and mutual inductance (M). Ferrite plates improved performance, maintaining a higher coupling coefficient (K = 0.83 at 20 mm vs. K = 0.8 without). Mutual inductance retention was also higher, reducing from 42.76 pH to 1.51 pH with ferrite, compared to 9.55 pH to 0.79 pH without. Magnetic flux density peaked at 11.89 mT with ferrite vs. 6.85 mT without optimizing magnetic field concentration. Economic analysis showed a reduced payback period from 10.1 to 6.3 years with efficiency improvements. Findings emphasize optimizing coil alignment, ferrite materials, and infrastructure to enhance large-scale WPT adoption.