Surface spiral parallel and antiparallel winding designs for low spatial voltage stress, high efficiency, inductive wireless power transfer systems

Surface spiral winding has been demonstrated to achieve low skin and proximity effects copper losses, and low air-gap magnetic flux density in MHz, kW level inductive wireless power transfer systems. Even though different dielectric geometries have been proposed to reduce dielectric losses, dielectric losses are still the limiting factor to further improve the coil-to-coil power transfer efficiency. In addition, high spatial voltage stress between the first turn and the end turn limits the power scalability due to the voltage breakdown possibility. This paper develops coil geometric solutions to reduce dielectric losses and proposes a surface spiral parallel winding design to improve the coil-to-coil power transfer efficiency, and a surface spiral antiparallel winding design to equalize dynamic voltage stress between adjacent turns and improve power scalability while maintaining high coil-to-coil power transfer efficiency.