Modeling and Analysis of Periodic Energy Control for Series–Series Wireless Power Transfer System

Wireless power transfer (WPT) is an emerging technology that enables efficient and convenient transmission of electrical energy wirelessly, and it has gained significant attention due to its potential to revolutionize various industrial, commercial, and consumer applications. This article presents a study on the series-series (SS)-compensated WPT system, focusing on characteristics analysis of periodic energy control (PEC) by the extended describing function (EDF) model. The model incorporates the influence of equivalent series resistors in the transmitting and receiving coils. The research highlights the feature of the PEC's input impedance angle always being greater than zero, which is attributed to the phase limitation of its driving circuit, making it suitable for zero voltage switching operations. In addition, the study reveals that the operating frequency range of PEC is discontinuous and exhibits a piecewise monotonic property against frequency splitting. This research provides valuable insights for the accurate modeling and understanding of PEC behavior in SS-compensated WPT systems. Finally, simulations and experiments are conducted, the EDF model is verified with high accuracy, and the frequency skip is demonstrated. The dc-dc system efficiency is up to 95.3% for the WPT system using PEC.