Split Impedance Tuning of Multistrand PCB Windings for Constructing Efficient Wireless Power Transfer Module

Printed Circuit Board (PCB) windings offer significant advantages for various applications, including ease of manufacturing, high repeatability, and compact size. These qualities are particularly beneficial in modular wireless power transfer (WPT) systems for unmanned aerial vehicles (UAVs), and other mobile devices which require compact dimensions and consistent parameters. However, a major challenge associated with PCB windings is substantial high-frequency AC resistance. To address this issue, this letter proposes a split impedance tuning method that is free from complex design. It employs capacitors to tune the impedance of each strand, thereby achieving optimal current distribution and reducing resistance. Experimental validation demonstrates that the proposed method reduces the resistance of the tested sample from 0.904 Ω to 0.326 Ω. The 527 W experimental WPT system, utilizing 76-mm-radius PCB windings operating at 300 kHz, achieves 90% efficiency.