Abstract: A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device may be a wireless charging mat or other device with a charging surface. The wireless power receiving device may be a portable electronic device receiving transmitted wireless power signals from the wireless power transmitting device while resting on the charging surface. During digital ping operations, low-power wireless power signals may be transmitted from the wireless power transmitting device. Information gathered during the digital ping such as wireless power transmission efficiency information, coupling coefficient information, Q-factor information, and coil inductance information may be used in determining whether a foreign object is present.

Abstract: A wireless power system has a wireless power transmitting device and a wireless power receiving device. During digital ping operations while the transmitting device and receiving device negotiate to establish a power level to use during normal operation, low-power wireless power signals may be transmitted to the receiving device from the wireless power transmitting device. Information gathered during the digital ping may be evaluated using a wireless-power-transmission-efficiency-to-digital-ping-rectifier-output-voltage relationship and using a normal-operation-wireless-power-transmission-efficiency-to-digital-ping-wireless-power-transmission-efficiency relationship to predict a wireless power transmission efficiency that would be experienced if the system were to enter normal operation. Based on this efficiency prediction, the system can issue alerts and can decide whether or not to enter normal operation.

Abstract: A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device may be a wireless charging mat or other device with a charging surface. The wireless power receiving device may be a portable electronic device receiving transmitted wireless power signals from the wireless power transmitting device while resting on the charging surface. During digital ping operations, low-power wireless power signals may be transmitted from the wireless power transmitting device. Information gathered during the digital ping such as wireless power transmission efficiency information, coupling coefficient information, Q-factor information, and coil inductance information may be used in determining whether a foreign object is present.