Wireless Power Transfer System with Reduced EMI Emission Employing Spread Spectrum Technique

Wireless power transfer (WPT) system based on a magnetic resonance between WPT coils has high parasitic capacitance due to the magnetic shielding materials of the coils. It induces high conductive electromagnetic interference (EMI) which travels along with the capacitive coupling. To reduce the EMI emission from the wireless charger, a WPT system with a spread spectrum technique (SST) is proposed in this paper for the EV charging application. The proposed wireless charger can reduce the peak and quasi-peak values of the EMI by spreading them into wide bandwidth. Moreover, it adopts the bridgeless rectifier at the secondary side, which can control the output voltage even though its operating frequency changes due to the SST. The performance of the proposed wireless charger including the output voltage regulation and EMI reduction capabilities are evaluated using simulation results based on PSIM software.