Omnidirecitional wireless power transfer for portable devices

In this paper, omnidirectional wireless power transfer system proposed by Intel and the University of Hong Kong are evaluated first based on FEA simulation and numerical model. The analysis results show that their systems cannot generate preferred omnidirectional magnetic field. Then, a new transmitter coil structure with preferred omnidirectional magnetic field is proposed. Two modulation methods of the excitation current are also studied and compared. Finally, three 6.78MHz LCL resonant converters are built to drive the transmitter coils and generate omnidirectional magnetic field. Near field probe is used to measure the magnetic field to verify both the proposed transmitter coil structure and modulation methods.