METHOD FOR DETECTING FOREIGN MATERIAL, AND APPARATUS AND SYSTEM THEREFOR

A power transmission method for a wireless power transmitter, the power transmission method including receiving, from a wireless power receiver, a foreign object detection (FOD) status packet including information on a reference quality factor or a reference peak frequency; determining whether a foreign object is present in a charging area of the wireless power transmitter based on the FOD status packet; and generating a foreign object detection indicator indicating whether the foreign object is present in the charging area of the wireless power transmitter based on a result of the determination and transmitting the generated foreign object detection indicator to the wireless power receiver, wherein the FOD status packet has a length of two bytes, wherein one byte of the FOD status packet includes a six-bit reservation field and a two-bit mode field, and wherein all bits of the reservation field are recorded as zero.