Inductive power transfer using diverted magnetic field

Abstract

In a wireless power transfer (WPT) system, a power-transmitting unit has a loop-shaped magnetic core formed by alternately arranging high-permeability (HP) and low-permeability (LP) core sections to give an interleaving pattern. A primary coil wound on the magnetic core provides a magnetic flux traveling therein when excited by an AC power source. A power-receiving unit has a pickup core shaped and dimensioned to overlie one or any LP core section, and to partially overlap HP core sections immediately adjacent to the LP core section that is overlay. The pickup core has a relative permeability higher than that of the aforesaid LP core section, causing at least a part of the magnetic flux to divert from this LP core section to the pickup core. The diverted part of magnetic flux generates electrical power in a secondary pickup coil wound on the pickup core to achieve WPT.