Apple Inc.
Wireless power system with foreign object detection

Abstract:

Wireless power transmitting equipment may transmit wireless power signals to wireless power receiving equipment. The wireless power transmitting equipment may have a wireless power transmitter coupled to a wireless power transmitting coil. The wireless power receiving equipment may have a wireless power receiving coil coupled to wireless power receiving circuitry such as a rectifier. Foreign object detection coil arrays may be formed from arrays of metal traces on printed circuit substrates that overlap the wireless power transfer coils. Control circuitry in the transmitting equipment and the receiving equipment may monitor signals from foreign object detection circuitry that is coupled to the coil arrays. The foreign object detection circuitry may produce in-phase and quadrature signals that are indicative of whether a foreign object is overlapping a foreign object detection coil array.