Method and device relating to time request for application message in wireless power transmission system

A wireless power receiver, comprising:

• a power pickup related to receiving wireless power from a wireless power transmitter;
• and
• a communicator/controller related to controlling the reception of the wireless power,
• wherein the wireless power receiver:
• enters a power transfer phase related to receiving the wireless power;
• transmits a first application message to the wireless power transmitter in the power transfer phase;
• and
• receives a second application message in response to the first application message from the wireless power transmitter in the power transfer phase;
• wherein the wireless power receiver completes receiving the second application message within a specific time period, and
• wherein a starting point of the specific time period is a end point of the first application message.

A method for transferring a wireless power in a wireless power transfer system, the method performed by a wireless power transmitter and comprising:

• entering a power transfer phase related to transferring the wireless power;
• receiving a first application message from a wireless power receiver in the power transfer phase;
• and
• transmitting a second application message in response to the first application message to the wireless power receiver in the power transfer phase;
• wherein the wireless power transmitter completes transmitting the second application message within a specific time period, and
• wherein a starting point of the specific time period is a starting point of the first application message.