Comparative Experiment of Conventional and Dynamic Theories for Wireless Power Transfer

This letter presents a comparative experiment of conventional and dynamic theories for wireless power transfer (WPT) systems. The dynamic theory considers the effect of the intermediate and far-fields on system operation, while it is neglected in the conventional theory. Theoretical analyses reveal that conventional theory cannot accurately predict the system behavior at high frequencies, where the transfer distance is comparable to the wavelength. In contrast, the dynamic theory can be applied over a wide frequency range to determine the optimal frequency. Experimental results demonstrate that a maximum power transfer efficiency (PTE) of 70.4% can be achieved at an optimal frequency of 29.7 MHz for a transfer distance of 3.5 times the antenna radius by applying the dynamic theory. Matching circuits were designed for source and load impedance at the optimal frequency. The system with matching circuits exhibits an overall efficiency of 44% at the same transfer distance.