Air-Core Inductive Coil for RF Filtering in Charger Cables

The patent introduces a common-mode filtering coil as an intermediary component in the charging cable. This coil acts as a mediator that allows desired power transmission while blocking harmful electromagnetic interference and harmonics generated by wireless device signals. The filtering coil is positioned between the power source and the wireless device, intercepting and attenuating the harmful frequencies before they can propagate further.

The patent converts the harmful electromagnetic interference and harmonics into a beneficial filtering function. By incorporating the common-mode filtering coil, the system uses the presence of these interfering signals to activate the filtering mechanism, which then attenuates them. The harmful high-frequency signals are transformed into heat or dissipated energy through the resistive losses in the coil windings, while the useful power transmission continues uninterrupted.

The common-mode filtering coil serves multiple functions simultaneously: it provides common-mode noise filtering, differential-mode signal transmission, and impedance matching. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving effective electromagnetic interference reduction.

The patent utilizes parameter changes in the filtering coil's inductance and resistance values to optimize its filtering performance. By carefully selecting the coil's physical parameters (number of turns, wire gauge, core material), the design achieves effective interference attenuation without requiring complex active filtering circuits or multiple components.