Optimal Cancellation Loop Termination to Reduce the Magnetic Field in WPT Systems

This article introduces an advanced original model to mitigate magnetic fields in near-field wireless power transfer (WPT) systems using a cancellation loop based on magnetic resonance coupling. Mitigating magnetic fields in WPT systems is challenging because these systems intentionally generate magnetic fields, and the current induced in the cancellation loop can create an opposing magnetic field that may degrade WPT performance. The proposed model, which uses a reduced equivalent circuit based on an original theory, can simultaneously manage WPT system performance and shielding effectiveness. The numerical and experimental results show that cancellation loops are highly efficient for WPT systems with high immunity to external fields, while they can cause significant performance degradation in more susceptible WPT systems. Finally, the article offers advanced guidelines for optimizing the cancellation loop by precisely tuning its terminal capacitance, ensuring maximum field mitigation with minimal impact on WPT performance.