Design of Transmitter Coil Antennas for Inductive Resonant Power Transfer

As people want to remove cables from their mobile devices, wireless charging becomes more and more important. Out of the different wireless power transfer (WPT) schemes, resonant inductive coupled WPT offers high transmission efficiencies paired with high spatial freedom in the position of the receiver and is thus of special interest in consumer electronics. To achieve high transmission efficiencies while allowing high spatial freedom, the transmitter coil of an inductively coupled WPT system has to be optimized. Here, we investigate the design of a printed-circuit-board (PCB) transmitter coil and consider skin effect, current crowding and proximity effect to optimize our design for a frequency of 6.78 MHz. In the end, we validate our theoretical model by comparing the predicted losses with the real losses in a WPT system resulting in a deviation of 10 % between model and measurement of a manufactured coil.