Electromagnetic interference and radiation from wireless power transfer systems

Wireless power transfer (WPT) technology is becoming increasingly popular for wireless charging of mobile phones and electrical vehicles. Because high power energy is transferred via air, however, the problem of electromagnetic radiated emission from WPT systems is expected to be serious. In this paper, an electromagnetic interface (EMI) and radiation from WPT systems are discussed. Three example technologies for suppressing the electromagnetic-field (EMF) noise and EMI noise from WPT systems are presented. EMF noise from different receiving (RX) coil topologies is characterized and an EMF noise suppression technology using a ferromagnetic material and metallic shielding is analyzed. A handheld resonant magnetic coupling charger (HH-RMCC), a WPT system with very low EMI noise, is then introduced. The proposed technologies for suppressing EMF and EMI noise from a WPT system will be helpful to design engineers.