WIRELESS POWER TRANSFER

A wireless power transfer system comprises a power transmitter () wirelessly providing power to a power receiver () via an electromagnetic power transfer signal. The power transmitter () comprises a transmitter coil () generating the power transfer signal and a driver () generating a drive signal for the transmitter coil () to generate the power transfer signal. A foreign object detector () executes a foreign object detection operation arranged to detect a presence of a foreign object in response to a property of the drive signal. A communicator () receives a power operating point indication from the power receiver () which represents a load power for a load of the power receiver (). An adapter () adapts the foreign object detection operation in response to the operating point indication being indicative of a change in the load power meeting a criterion.