Design of Resonant Circuit Components to Suppress Both EMF and EMI in Wireless Power Transfer Systems for Electric Vehicles

Wireless power transfer (WPT) systems use a magnetic field as the medium for transferring power wirelessly. During the transfer process, there are two magnetic fields, which are called the coupling magnetic field and the leakage magnetic field. The leakage magnetic field can cause electromagnetic field (EMF) and electromagnetic interference (EMI) issues. In WPT systems, when transferring power from source to load, EMF can affect humans due to the strong magnetic field. EMI can cause interference with other electronic devices due to the harmonic magnetic field. Before a WPT system can be commercialized, the EMF and EMI issues must both be solved. In addition, EMF and EMI regulations must be met. This article proposes a method of designing resonant circuit components to suppress EMF and EMI in WPT systems for electric vehicles (EVs). The processes of suppressing EMF and EMI are explained. The proposed method was verified through simulation and experiment. Results showed that EMF can be suppressed by up to 50%, and EMI can be suppressed by up to 14 dB.