FOREIGN OBJECT AND VALID RECEIVER DETECTION TECHNIQUES IN WIRELESS POWER TRANSFER

Systems and methods are presented for detecting a foreign object on a wireless power transmitter, the transmitter configured to wirelessly charge power to a device when the device is on or in close proximity to a charging surface of the transmitter. The system includes a wireless power transmitter and a controller coupled to the wireless power transmitter. The controller is configured to detect a first resonant frequency of the wireless power transmitter when an object is not present on or is not in close proximity to the charging surface of the wireless power transmitter, detect a second resonant frequency of the wireless power transmitter in response to applying a power to the wireless power transmitter, compare the first resonant frequency and the second resonant frequency, and based on the comparison, determine whether an object is on or is in close proximity to the charging surface of the wireless power transmitter.