System for wireless power charging

Abstract

According to a first aspect of the present disclosed subject matter, a method for foreign object detection in a system having a relay adapted to inductively transfer power for charging a device and a transmitter having a controller configured to inductively transmit to the relay the power for charging the device, wherein the transmitter and the relay are separated by a medium, wherein the controller is capable of communicating with the device, the method comprising operations by the controller: determining power consumed by the transmitter; determining power loss on the transmitter according to continuous measurements of AC output current; obtaining coupling factor between the transmitter and the relay; determining power loss on the relay based on continuous measurements of AC output current and coupling factor; subtracting from the power consumed by the transmitter the power loss on the transmitter and power loss on the relay; obtaining from the device consumed power of the device; comparing a result of the subtracting to the consumed power of the device; determining foreign object presence.

Dependencies are inferred from the claim text.