Method for detecting foreign material, and apparatus and system therefor

Abstract

A power transmission method for a wireless power transmitter, the power transmission method including receiving, from a wireless power receiver, a packet including a foreign object detection (FOD) status packet; 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 includes information on a reference quality factor or a reference peak frequency, and wherein the packet further includes at least one of a signal strength packet, an end power transfer packet, a power control hold-off packet, a configuration packet, an identification packet for transmitting receiver identification information, an extension identification packet, a general request packet, a special request packet, a control error packet, a renegotiation packet, a 24-bit reception power packet, an eight-bit reception power packet, and a charging status packet.