Analysis and Design of a 6.78 M Wireless Power Transfer System With Strong Misalignment Tolerance Based on Simplified Impedance Trajectory Tracing

Megahertz wireless power transfer (WPT) systems are sensitive to circuit parameters, where coupling coefficient k variations can directly and significantly affect the system dc–dc gain and efficiency. This letter proposes a simplified impedance trajectory tracing (SITT) design method, which makes full use of the respective advantages of static impedance compression and dynamic matching network. While ensuring high power density, it improves the robustness of the system for strong misalignment tolerance. Closed loop and hysteretic control are adopted to ensure stable constant power output, and integrated inductors are also fabricated. When k varies from 0.1 to 0.4, the system efficiency is always higher than 80%, and even reaches 88.5%.