Abstract: An electronic device configured to transmit or receive power by inductive power transfer is disclosed. The electronic device includes an inductive charging receiver to receive electromagnetic power through a surface from a magnetic field at an operating frequency within a frequency range of 100 kHz to 1 MHz from an inductive charger. The inductive charging receiver includes a substantially planar inductive coil with a metallic spiral-shaped conductor, and further includes an electrically conductive shield positioned between the conductor of the inductive coil and the surface of the electronic device such that the shield covers the metallic spiral-shaped conductor. The shield may include a metal layer that has a metal thickness in a range of 1 to 70 micrometers, or the shield may be non-metallic. Transmission of electromagnetic power through the shield is allowed in the frequency range for inductive power transfer.

Abstract: A system and method for variable power transfer in an inductive charging or power system. In accordance with an embodiment the system comprises a pad or similar base unit that contains a primary, which creates an alternating magnetic field. A receiver comprises a means for receiving the energy from the alternating magnetic field from the pad and transferring it to a mobile device, battery, or other device. In accordance with various embodiments, additional features can be incorporated into the system to provide greater power transfer efficiency, and to allow the system to be easily modified for applications that have different power requirements. These include variations in the material used to manufacture the primary and/or the receiver coils; modified circuit designs to be used on the primary and/or receiver side; and additional circuits and components that perform specialized tasks, such as mobile device or battery identification, and automatic voltage or power-setting for different devices or batteries.