A Planar Omnidirectional Wireless Power Transfer Platform for Portable Devices

Abstract

Recently, omnidirectional wireless power transfer (WPT) has gained extensive attention globally. However, it is difficult to integrate such system with common home furniture for its three-dimensional (3-D) structure, which degrades its practicality. Targeting at this challenge, this article proposes a novel planar omnidirectional WPT system, enabling 3-D omnidi-rectional WPT for consumer electronics, such as mobile phones and earphones. It consists of three sets of planar coils, which can generate magnetic field in three dimensions, enabling the receiver to be charged in all positions and orientations. Besides, the decoupling performance of the proposed coil structure is verified. Afterwards, a LCCL-LC resonant converter is utilized to achieve the constant output voltage gain at resonant frequency. Finally, in the experiment, three sets of coils are integrated as PCB windings and the magnetic field is measured to verify the omnidirectional magnetic field distribution under 6.78MHz. When charging a 5-W receiver for portable devices, the output voltage will be between 16-24V while the overall efficiency is 70%-72.5% with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$x$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$y$</tex> misalignment. Considering the angular misalignment, the efficiency remains between 28%-53%.