WIRELESS POWER RECEIVING DEVICE AND METHOD OF OBTAINING QUALITY FACTOR OF WIRELESS POWER TRANSMITTING DEVICE

A wireless power transmitting device according to an embodiment of the present specification relates to a wireless power transmitting device for transmitting wireless power to a wireless power receiving device, and comprises: a power conversion circuit including a primary coil for transmitting the wireless power to the wireless power receiving device; and a communication/control circuit for communicating with the wireless power receiving device and controlling the power conversion circuit, wherein, before transmitting the wireless power to the wireless power receiving device, the communication/control circuit temporarily applies driving power to the primary coil and then stops the transmission of the driving power, and obtains a quality factor on the basis of a change in the voltage or current of the primary coil during a period of time in which the transmission of the driving power is stopped.