Receiving‐coil structure reducing stray AC resistance for resonant coupling wireless power transfer

Abstract

Resonant inductive coupling wireless power transfer is widely known to be a possible convenient power supply method for the small mobile apparatus. However, the limited receiving-coil size tends to lower the efficiency and limit the output power owing to the small mutual inductance and comparatively large stray alternating current (AC) resistance of the receivingcoil. This study mitigates this issue by proposing a novel receiving-coil structure. This proposed structure comprises a coil and a drum core with a thin axis. The coil is wound on the axis to form a single winding layer. The proposed structure can reduce stray AC resistance by suppressing the proximity effect and reducing the wire length without deteriorating the mutual inductance significantly. Therefore, better efficiency and larger output power can be achieved. Simulations and experiments were performed to verify the proposed structure. Consequently, both simulations and experiments supported the reduction in AC resistance compared to the conventional structure. Furthermore, the experiment revealed improvements by the proposed structure in both efficiency and output power. These results support the effectiveness of the proposed structure for wireless power transfer to small mobile apparatus.

Autonomous Resonant Frequency Tuner for a 6.78MHz Inductive Coupling Wireless Power Transfer System to Stably Maximize Repeater Current

“…Owing to this feature, the WPT technique can be one of the fundamental key technologies for the coming information society because this technique is convenient for the power supply to many small Internet-of-Thing (IoT) devices dispersed in the wide space such as the radio frequency identification tags (RFID tags (1) (2) ) and small sensors (1) , which are increasingly utilized in the factories, warehouses, and hospitals. The WPT can also be a key for advanced medical technologies like biomedical implants (3) and capsule endoscopies (4) (5) because it can solve the need for internal batteries and therefore can miniaturize these medical devices. This perspective motivates the researchers to investigate the WPT technique for charging many small devices in a wide space.…”