Power Handling Capability of Self-Resonant Structures for Wireless Power Transfer

The range and efficiency of resonant inductive wireless power transfer depends on the quality factor of the resonant coils. A multilayer self-resonant structure (MSRS), made of many alternating layers of thin foil conductors and dielectric, has been shown to have a quality factor many times higher than conventional resonant coils of similar size. To date, the MSRS has only been modeled and tested for small-signal excitations and the impact of large-signal excitations on the MSRS performance has not been considered. This paper explores large-signal effects such as Steinmetz core loss, temperature dependence of winding and core losses, and the thermal effect of loss in order to determine the power handling capability of the MSRS. The analysis shows that a 6.6 cm-diameter prototype MSRS is capable of transferring as much as 10.7 kW over a 0.5 cm gap and 760 W over 2.2 cm, for maximum 40 °C temperature rise in a 25 °C environment.