Low-Radiation Multiple-Coil Wireless Charger Using Detuned Compensation

This article investigates a low-radiation multicoil wireless charger driven by a single inverter, addressing the challenge of reducing radiation from unloaded transmitter (TX) coils in multicoil systems. Traditional methods often require multiple inverters or complex switching techniques to selectively activate TX coils, which increases system complexity and cost. Instead, this work proposes a detuned compensation technique that naturally attenuates the current in unloaded TX coils, thereby reducing radiation without the need for additional control circuits. The approach is analyzed using a two-coil system and then extended to a more general multicoil scenario. A five-coil TX system is experimentally demonstrated, achieving a current attenuation ratio exceeding 6 and maintaining an efficiency above 70% when charging a single 10-W receiver (RX). The results show a significant reduction in radiation field strength compared to a benchmark system, validating the effectiveness of the proposed detuned compensation technique. This method offers a promising solution for low-radiation wireless charging in applications requiring high mobility and adaptability.