Wireless power transmitting device for wirelessly transmitting power, wireless power receiving device for wirelessly receiving power, and operation method thereof

A wireless power transmitting device comprising:

• a transmission coil;
• a DC/DC converter configured to output a driving voltage;
• an inverter configured to output AC power to the transmission coil, using the driving voltage;
• at least one controller;
• and
• memory storing instructions that, when executed by the at least one controller, cause the wireless power transmitting device to:
• output a first control signal for generating the AC power having a first frequency to the inverter, so that the inverter outputs, to the transmission coil, the AC power having the first frequency based on the first control signal,
• identify voltage information of a demodulated signal generated by demodulating a signal applied to the transmission coil while the AC power having the first frequency is applied to the transmission coil, and
• output, to the inverter, a second control signal for generating the AC power having a second frequency different from the first frequency, instead of the first control signal, based on a first peak-to-peak value identified in the voltage information being a preset first value or more, and
• wherein the inverter outputs the AC power having the second frequency to the transmission coil based on the second control signal.