Transmitter coil design for resonant wireless power transfer

Abstract

The paper discusses the Tx coil design for resonant wireless power transfer. Resonant power transfer has attractive features over inductive power transfer i.e. multi-device charging and spatial flexibility, both require large coil size. However, the coil size cannot exceed a certain limit to guarantee efficient power transfer. The Tx coil design impacts the whole system performance, we show how it impacts the PA behavior, the system reliability, and the design space. The power coupling for planar coils takes place through the normal magnetic field component H z , hence, that field component should be uniform as we are going to show. Based on field uniformity a Tx coil synthesis process is introduced, where the coil turns shape are optimized to produce the minimum field variation, only low computational burden magnetic equations can be used to permit the high number of iterations, the final design is verified using a 3D Full wave EM tool.