6.78-MHz Wireless Power Transfer With Self-Resonant Coils at 95% DC-DC Efficiency

• Published in: IEEE transactions on power electronics Vol. 36; no. 3; pp. 2456 - 2460
• Main Authors: Gu, Lei, Zulauf, Grayson, Stein, Aaron, Kyaw, Phyo Aung, Chen, Tuofei, Davila, Juan Manuel Rivas
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-03-2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Capacitance; Coils; Coupling circuits; electromagnetic coupling; inductive charging; Integrated circuit modeling; power amplifiers; Semiconductors; Silicon; Topology; tuning; Wide bandgap semiconductors; Wireless communication; Wireless power transfer; Wireless power transmission; zero voltage switching
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2020.3014042

Megahertz-frequency inductive wireless power transfer holds the promise of compact and efficient wireless power transfer. Unfortunately, due to high-frequency losses in wide-bandgap semiconductors and low-<inline-formula><tex-math notation="LaTeX">Q</tex-math></inline-formula> high-frequency coil designs, these systems are universally less efficient, on a dc-dc basis, than wireless power systems operating at conventional frequency regimes. This letter describes the design considerations for inductive wireless power transfer systems operating at 6.78 MHz. With a novel high-frequency resonant amplifier topology, a high-<inline-formula><tex-math notation="LaTeX">Q</tex-math></inline-formula> self-resonant coil structure, and a better understanding of <inline-formula><tex-math notation="LaTeX">C_{oss}</tex-math></inline-formula> losses in wide-bandgap power semiconductors, we demonstrate 6.78- MHz wireless power transfer systems that achieve 95% dc-dc efficiency at power levels up to and beyond 1 kW.