WIRELESS POWER TRANSFER SYSTEM

A wireless power receiver, method, and corresponding processing circuitry for the same are disclosed. The wireless power receiver includes a receiver coil configured to receive a wireless power transfer signal transmitted by a wireless power transmitter and a load coupled to the receiver coil. The wireless power receiver further includes communication circuitry configured to communicate a synchronization message to the wireless power transmitter which indicates time durations for repeating time intervals of foreign object detection and wireless power transfer. The foreign objection detection time periods correspond to periods of reduced power transfer to improve detection of foreign objects. The communication circuitry is configured to communicate a measured parameter, such as power received from an electromagnetic test signal, to the wireless power transmitter during the synchronized foreign object detection time periods, such that the wireless power transmitter can detect the presence or absence of a foreign object.