Reduction of Electromagnetic Emissions Generated by Inductive Resonant WPT Systems Using Multi-Switching-Frequency-Based Method

Being switch-mode in nature, wireless power transfer systems (WPT) emit significant conducted electromagnetic emissions (EME). In this paper for the first time multi switching frequency scheme is applied to closed-loop WPT systems for reduction of conducted EME. In this method inductive resonant WPT system operates at different discrete switching frequencies sequentially. The effect of the multi switching frequency scheme on main performance characteristics of inductive-resonant wireless battery charger operating in constant current mode is analyzed by using simulations. Performance characteristics of the WPT system with the multi switching frequency scheme are compared with that of WPT system without modulations and with classical switching frequency modulation. It is shown that wireless battery charger with the multi switching frequency scheme exhibits performance similar to performance of wireless battery charger with classical switching frequency modulation but complexity of control is lower.