Flexible PCB Coupler for Omnidimensional Wireless Power Transfer System (TPEL, under review)

Abstract

Wireless power transfer (WPT) in the megahertz operating frequency range is a promising method for enhancing charging spatial flexibility. However, the traditional planar coupler has high requirements for the position and angle of the receiving device, which limits the practical use of WPT. This article proposes a flexible print circuit board (PCB) coupler that generates a centrally symmetric magnetic field, resulting in stable mutual inductance between transmitting (Tx) and receiving (Rx) coils. The flexible PCB couplers eliminate the need for current amplitude or phase control circuits. Each flexible PCB coil can shape itself according to the device to be charged wirelessly, enabling the Rx coil to receive energy wirelessly regardless of its self-rotation or revolution around the Tx coil. Several practical experiments have validated the feasibility of the proposed omnidirectional WPT system. To test the omnidirectional operation, three different shapes of receiving coils (cylinder, square prism, and triangular prism) are manufactured, and they achieve a total output power of 15 W and 68.18% efficiency when activated simultaneously. The newly proposed omnidirectional WPT system eliminates the need for specific positions and directions for numerous charging devices, further advancing the power solution for the ubiquitous Internet of Things (IoT).