Low loss magnetic design for wireless power transfer

Abstract

An electromagnetically power transmission system to transmit power at a high power density and with a high efficiency under consideration of EMC aspects is proposed. Product requirements like size and weight are taken into account. The system uses the resonance wave coupling and an impedance adaption for multi-stage conversion is implemented to optimize efficiency and impedance matching. The transferred power is up to 180 W at a frequency of 6.78 MHz with a distance between 30 mm and 80 mm. The results show that an efficiency up to 88% can be achieved. The transmitted power density reaches up to 14 W/cm2. It is shown that due to the evanescent wave resonance coupling the system emits only very little radiation and thus is capable to keep EMC/EMF regulations. Wireless power transfer applications such as electric vehicle charging and wireless power drive for LED lighting through a wall are demonstrated.