Multi-coil wireless charging method and device and system therefor

A method for transmitting wireless power to a wireless power receiver by a wireless power transmitter having a plurality of transmission coils, the method comprising:

• simultaneously transmitting a first detection signal for detecting presence of the wireless power receiver using differently assigned frequencies for each of the transmission coils;
• identifying at least one frequency corresponding to a transmission coil through which a first signal strength indicator corresponding to the first detection signal has been received;
• transmitting a second detection signal using the identified at least one frequency;
• and
• determining a frequency to be used for power transmission based on a second signal strength indicator received corresponding to the second detection signal.

A wireless power receiver for wirelessly receiving power from a wireless power transmitter, the wireless power receiver comprising:

• a reception coil;
• a frequency filter configured to filter first to n-th frequencies for an AC signal received through the reception coil;
• and
• a main controller configured to identify at least one frequency at which a first detection signal is received, based on the filtered signal,
• wherein the main controller controls a first signal strength indicator corresponding to the first detection signal so as to be transmitted through the identified at least one frequency.