Comparison of Different Coil Structures for Wireless Power Transfer Using Magnetic Resonant Coupling

Magnetic resonant coupling is preferred over magnetic induction because of its higher efficiency and ability to transfer power for longer distances. The main components of wireless power transfer system are a primary transmission coil connected to power source and a secondary receiving coil. Both coils are separated by some air gap. Primary coil generates an alternating magnetic field and flux, which triggers current to flow through a nearby receiver coil. This paper describes the power transfer between coils, coil position, size of coils, number of coil rotations, intermediate coils. This paper also deals with the variation of mutual inductance and coupling coefficient over a wide range of distance for each of the three coil structures namely - square spiral, circular spiral and helix. The analysis is performed with the assistance of ANSYS Electronics software.