Apple Inc.

Arash Mehrabi

Zaki Moussaoui

Gianpaolo Lisi

Dmitry Berdnikov

Moshe H Malkin

Zhiyuan Hu

Michael F Jean

Alin I Gherghescu

Atul A Salvekar

Jose V Santos Martinez

Brian D Mariner

Benjamin M Oztalay

Andrew H Jones

Bo Zhou

Portable electronic devices such as cellular telephones, wristwatch devices, tablet computers, wireless earbuds, and other portable devices use batteries. The batteries in these devices may be charged using a wireless power system. For example, a user may place devices such as tablet computers and cellular telephones on a wireless charging puck or mat to wirelessly charge these devices. Wireless power systems include a power transmitting device and a power receiving device. Coils in the power transmitting and receiving devices are used to transmit and receive wireless power signals. The coupling between the transmitting and receiving coils may affect the wireless charging efficiency and the power produced in the receiving device. Disclosed herein are feedback control schemes to optimize efficiency of wireless power transfer systems.

Feedback control schemes for wireless power transfer circuits

A wireless power system has first and second electronic devices. The first electronic device may receive power from an alternating-current-to-direct-current power converter. A magnetic sensor and/or other sensing circuitry may detect when a second electronic device is attached to the first electronic device. In response to detecting device attachment and receipt of power from the power converter, the first electronic device sends test wireless power signals to the second electronic device. During reception of the test signals, the second electronic device adjusts a ballast load so that output current from a rectifier in the second electronic device flows through the ballast load. The output of the rectifier is measured and compared to a threshold voltage. If the rectifier output voltage exceeds the threshold, the first electronic device is directed to alert the user that wireless charging of the second electronic device is commencing.

Wireless power system with charging alerts

A wireless power system may include an electronic device and a removable case. The electronic device and removable case may include wireless charging coils that are inductively coupled when the electronic device and the removable case are physically coupled. In a first mode, while the removable case is inductively coupled to the electronic device and the electronic device is not connected to a wired power source, a coil in the removable case transmits wireless power signals to the electronic device. In a second mode, while the removable case is inductively coupled to the electronic device and the electronic device is connected to a wired power source, the coil in the removable case receives wireless power signals from the electronic device. In a third mode, the removable case receives wireless power with a first coil and transmits wireless power to the electronic device with a second coil.

Wireless power mode switching

A wireless power transmitting device transmits wireless power signals to a wireless power receiving device using a wireless power transmitting coil. The wireless power receiving device may transmit data packets to the wireless power transmitting device. The wireless power transmitting device may include a data receiver that is coupled to the wireless power transmitting coil and that receives the transmitted data packets. The data receiver may be configured to demodulate the received data packets. The data packets may include at least preamble bits, start bits, and data bits encoded as biphase half-bit signals in accordance with a predefined wireless power transfer protocol. During demodulation, the receiver may perform preamble detection, start bit detection, and data bit detection by comparing the input signals to corresponding reference patterns using a maximum likelihood sequence detection scheme. Phase recovery may be employed throughout to help provide immunity to phase change.

Methods and apparatus for performing demodulation using maximum likelihood sequence matching in a wireless charging device

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Menlo Park, CA, United States of America

Arash Mehrabi