Multi sub-coil flux pipe couplers and their use in a misalignment-adaptive wireless power transfer system

Abstract

Flux pipe couplers are compact coils used in wireless power transfer (WPT) applications. The first part of this paper investigates the effect number of sub-coils on the magnetic characteristics. Flux pipe couplers with more than two sub-coils exhibit higher coupling coefficient as compared to traditional flux pipe couplers with two sub-coils. Furthermore, multi sub-coil flux pipe couplers better distribute the magnetic flux inside the core, making them attractive in high power applications. The second part presents an experimental WPT system employing multi sub-coil flux pipe couplers with three sub-coils. More than 82% power transfer efficiency is observed when couplers are separated with 100 mm vertical gap. Lateral misalignments up to 200 mm are then applied, and meantime, the separation between sub-coils is varied for achieving maximum efficiency. A near-constant efficiency is obtained up to 150 mm misalignment. Therefore, this paper announces another potential use of flux pipe couplers realizing an adaptive WPT system.