METHOD FOR DETECTING FOREIGN MATERIAL, AND APPARATUS AND SYSTEM THEREFOR

A wireless power transmission method including receiving, from a wireless power receiver, a first foreign object status packet and a second foreign object status packet; and transmitting, to the wireless power receiver, a foreign object detection indicator indicating whether a foreign object is present in a charging area of a wireless power transmitter, wherein the first foreign object status packet includes a first reference value and mode information, wherein the second foreign object status packet includes a second reference value and mode information, wherein the mode information of the first foreign object status packet indicates whether the first reference value is a reference quality factor or a reference peak frequency of the wireless power receiver, and wherein the mode information of the second foreign object status packet indicates whether the second reference value is the reference quality factor or the reference peak frequency of the wireless power receiver.