METHOD FOR DETECTING FOREIGN MATERIAL, AND DEVICE AND SYSTEM THEREFOR

A wireless power transmitter including a reception unit configured to receive a foreign object detection (FOD) status packet from a wireless power receiver; and a transmission unit configured to transmit a response indicating whether a foreign object is present in a charging area of the wireless power transmitter to the wireless power receiver, wherein the FOD status packet includes a mode bit field, wherein the mode bit field indicates whether the FOD status packet includes a reference peak frequency of the wireless power receiver, wherein the reference peak frequency is pre-allocated to the wireless power receiver, and wherein the response is determined using a measured peak frequency of a transmitted power signal and an adaptive threshold frequency based on the reference peak frequency included in the FOD status packet.