Device and method for controlling transmission of power in wireless power transmitting system

A wireless power transmitter configured to transmit wireless power, the wireless power transmitter comprising:

• a power converter configured to transmit the wireless power to a wireless power receiver based on a primary coil array through magnetic coupling,
• wherein the primary coil array comprises a plurality of primary coils;
• and
• a communicator & controller configured to control the wireless power,
• wherein the wireless power transmitter is configured to:
• perform an analog ping,
• wherein the analog ping results in a first set of primary cells, among the plurality of primary coils of the wireless power transmitter;
• for each of the primary cells in the first set, perform, in a ping phase, a digital ping after performing the analog ping;
• receive, from the wireless power receiver in the ping phase, at least one signal strength packet after the digital ping;
• select a second set of primary cells based on the at least one signal strength packet related to the digital ping among the first set related to the analog ping;
• receive, from the wireless power receiver in a configuration phase, a configuration packet including an out-band field after the ping phase,
• wherein the out-band field informs whether the wireless power receiver supports an out-band communication or not;
• and
• receive, from the wireless power receiver in a negotiation phase, a foreign object detection (FOD) status packet after the configuration phase,
• wherein the FOD status packet includes a reference quality factor value,
• wherein the wireless power transmitter performs FOD based on the reference quality factor value.