METHOD FOR DETECTING FOREIGN MATERIAL, AND APPARATUS AND SYSTEM THEREFOR

A wireless power transmitter that transmits power to a wireless power receiver, the wireless power transmitter including a wireless communication unit configured to communicate with the wireless power receiver; and a controller, wherein the wireless communication unit receives a foreign object detection (FOD) status packet from the wireless power receiver, wherein the controller determines whether a foreign object is present in a charging area of the wireless power transmitter on the basis of the FOD status packet, wherein the wireless communication unit transmits, to the wireless power receiver, a foreign object detection indicator indicating whether the foreign object is present in the charging area of the wireless power transmitter on the basis of a result of the determination, wherein the FOD status packet includes information on a reference quality factor or a reference peak frequency, wherein the FOD status packet has a length of two bytes, wherein one byte of the FOD status packet includes a 6-bit reservation field and a 2-bit mode field, and wherein all bits of the reservation field are recorded as zero.