Exploring Feasibility and Efficiency of a WPT System Comprising a Flat Spiral Coil Nested Within a Large Helical Coil

In this work, we investigate a feasibility of a noncanonical case of a wireless power transfer (WPT) system which comprises a spiral coil nested within a helical coil. This kind of a configuration would make sense in an indoor environment where a concealed room-sized helical coil would be used as a source and a gadget-sized spiral coil as a receiver of a wireless charging system, which would require no need for a personal charging pad or any special extension to charge one's device wirelessly. We have built a simulation model and a small laboratory prototype. The scenario was further explored by simulations with gradually adapting the structure size towards the realistic sizes of the coils. The challenge arises from multiple factors that entail optimizing the geometry of the transmitter and the receiver, calculating their equivalent electrical parameters, and the resonant frequency.