Apple patents wireless charging safety check for metal objects

1. Controller and communication circuitry for a wireless power transmitter, the controller and communication circuitry being adapted to couple to an inverter and a wireless power transfer coil of the wireless power transmitter and control the inverter to regulate wireless power transfer to a wireless power receiver, the controller and communication circuitry comprising logic or programming that detects a foreign object influenced by an electromagnetic field associated with wireless power transfer to the wireless power receiver by: receiving from the wireless power receiver an indication of receiver power associated with the wireless power transfer; determining a measured power loss associated with the wireless power transfer by comparing the indication of receiver power to a transmitter power measured by the wireless power transmitter; computing a predicted power loss based on the indication of receiver power and one or more coefficients corresponding to a baseline wireless power transmission between the wireless power transmitter and the wireless power receiver; and determining that a foreign object is present if the measured power loss exceeds the predicted power loss by more than a threshold; and responsive to determining that the foreign object is present, mitigating presence of the foreign object by reducing a power level of or suspending the wireless power transfer using the wireless power transfer coil.