A novel planar wireless power transfer system with strong coupled magnetic resonances

A novel wireless power transfer system using strongly coupled magnetic resonances is proposed. In the proposed design, both the transmitter coil set and the receiver coil set are fully planar, comprising of two printed spiral resonator coils and co-planar source and load loops. Comparisons in both quality factor and power transfer efficiency of the design with self-resonant printed spirals and with capacitor-loaded printed spirals are made. In addition, the power transfer efficiency of the planar design with small inductances is also discussed. Measurement results show that the proposed design exhibits a power transfer efficiency of 74.1% at the distance of 200 mm. The planar structure and high transfer efficiency make the proposed design a suitable candidate for wireless power transfer of small portable electronic devices. Finally, the effects of ferrite material and conductive objects on the proposed system are also investigated.