Transmitting coil achieving uniform magnetic field distribution for planar wireless power transfer system

A 20 cm by 20 cm transmitting coil is designed for an inductively-coupled power transfer system. The coil design is a spiral, whose geometry is optimized to ensure an even magnetic field distribution. This guarantees uniform power delivery regardless of recieving coil position. The transmitting coil is tested using Litz wire, a switchmode power amplifier, and a 6 cm by 8 cm recieving coil connected to a rectifier and a variable load. The system achieves a maximum efficiency of 80.9% and a maximum power delivery of 11.8 W. At a fixed load, the power delivery has a coefficient of variation of 2.2% as the recieving coil´s position is varied on the transmitter. In general, the system efficiency is high and insensitive to receiver placement as well as loading conditions.