Wireless power transmission device and control method therefor

A wireless charging system, comprising:

• a transmitter formed to transmit power in a wireless manner;
• and
• a receiver formed to receive wireless power from the transmitter,
• wherein the transmitter comprises:
• a power supply unit configured to supply power to transmit power to the receiver in a wireless manner;
• and
• a power transmission control unit configured to:
• periodically generate a signal having a waveform at a first frequency for each period, wherein the first frequency is different from a preset resonant frequency between the transmitter and the receiver;
• measure a variation of an attenuation factor of the generated signal for the each period;
• detect a second frequency included in the generated signal, wherein the second frequency is different from each of the first frequency and the preset resonant frequency, and wherein the second frequency is related to a mutual inductance value between the transmitter and the receiver;
• determine a type of an external material corresponding to the receiver and an alignment state between the transmitter and the receiver based on the measured variation of the attenuation factor and the detected second frequency;
• and
• transmit power to the receiver in the wireless manner based on the determined type of the external material and alignment state.

A wireless power transmission method of a wireless power transmitter for transmitting power in a wireless manner, the wireless power transmission method comprising:

• periodically generating a signal having waveform at a first frequency, wherein the first frequency is different from a preset resonant frequency between the wireless power transmitter and the receiver;
• measuring a variation of an attenuation factor of the generated signal for the each period;
• detecting a second frequency included in the generated signal, wherein the second frequency is different from each of the first frequency and the preset resonant frequency, and wherein the second frequency is related to a mutual inductance value between the wireless power transmitter and the receiver;
• determining a type of an external material corresponding to the receiver and an alignment state between the wireless power transmitter and the receiver based on the measured variation of the attenuation factor and the detected second frequency;
• and
• transmitting power to the receiver in the wireless manner based on the determined type of the external material and alignment state.