Planar Wireless Charging Technology for Portable Electronic Products and Qi

TLDR

This review traces wireless power from Tesla’s 1890s experiments through key historical milestones to the 2010 launch of the Qi standard for portable electronics. It explains how modern near‑field magnetic coupling enables planar wireless charging, comparing horizontal and vertical flux designs, and outlines the key features—localized charging, load identification, and positional freedom—adopted by the Wireless Power Consortium in the Qi standard. The article highlights industrial uses of wireless power since the 1960s and discusses recent domino‑resonator research that promises mid‑range charging capabilities.

Abstract

Starting from the basic principles of Tesla's wireless power transfer experiment in the 1890s, this review article addresses the key historical developments of wireless power and its modern applications up to formation of the world's first international wireless power standard "Qi" launched in 2010 for portable electronics. The scientific principles laid down by Nicolas Tesla for wireless power transfer, which still remain valid today, are first explained. Then, modern wireless power applications based on nonradiative (near-field) magnetic coupling for short-range applications are described. Some industrial application examples emerging since the 1960s are highlighted. The article then focuses on the comparison of the horizontal and vertical magnetic flux approaches developed in the early 1990s for low-power planar wireless charging pads. Several critical features such as localized charging, load identification, and freedom of positioning that are essential to wireless charging of portable electronic devices are explained. The core technologies adopted by the Wireless Power Consortium (WPC) for the "Qi" Standard in 2010 are summarized. Finally, the latest research and developments of wireless power transfer for midrange applications based on the domino-resonator concept and their future application potential are described.