Apple Inc.

Patrin Illenberger

Saining Ren

Aiguo Hu

Ho Fai Leung

Wynand L Malan

Bo Long

Andrew R Connell

Qi Zhu

Metal object detection may be performed in a wireless power system by monitoring the 5th or other order harmonic current of a dual-frequency power transmitter driven by a voltage-fed inverter with square-wave output. While power transfer is maintained by tuning at the fundamental frequency, the transmitter circuit is tuned simultaneously at the 5th order frequency or other harmonic frequencies to increase or decrease the flow of the harmonic current for when a metal object is present. The receiver circuit may include a notch filter to filter out the 5th order frequency. With the dual-frequency tuning configuration, the presence of a metal object causes a significant drop of the increase in the harmonic current at the transmitter side while the receiver behaves as an open circuit with no effect on power transfer. The harmonic tuning circuit may be switched off as necessary to leave only the fundamental frequency for power transfer.

Harmonic current monitoring in a wireless power system

A wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to a wireless power receiving device. The wireless power transmitting coil is located in a housing. The housing has a circular outline and contains one or more magnets that couple to corresponding magnets in the wireless power receiving device to help align a wireless power receiving coil in the wireless power receiving device to the wireless power transmitting coil in the wireless power transmitting device. A circular array of capacitive sensor electrodes is supported by the housing at a location that overlaps the wireless power transmitting coil. Capacitive sensor measurements from the capacitive sensor array are analyzed to determine whether a foreign object such as a coin or paperclip is present between the housing and the wireless power receiving device.

Wireless power devices with capacitive foreign object detection sensors

Growing community of inventors

Auckland, New Zealand

Patrin Illenberger