Apple Inc.

Dmitry Berdnikov

Zaki Moussaoui

Weihong Qiu

Nan Liu

Arash Mehrabi

Sumant Ranganathan

Christopher M Pinciuc

Rex H Huang

Jukka-pekka J Sjoeroos

Zhiyuan Hu

Alin I Gherghescu

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 have a wireless power transmitting device and a wireless power receiving device. The wireless power receiving device may have a receive coil that receives wireless power signals from the wireless power transmitting device and may have a rectifier that produces direct-current power from the received wireless power signals. The wireless power transmitting device may have an array of transmit coils. Each transmit coil has a respective magnetic coupling coefficient characterizing its magnetic coupling with the receive coil. The wireless power transmitting device may have control circuitry that uses the magnetic coupling coefficient values in selecting transmit coils to use in transmitting wireless power to the wireless power receiving device.

Wireless power system with coupling-coefficient-based coil selection

A power system has a wireless power transmitting device and a wireless power receiving device. Coils in the transmitting device may include a circular coil overlapped by first and second rectangular coils at a charging surface. The rectangular coils each include straight segments extending over a central region of the circular coil. Control circuitry can activate the circular coil to transmit wireless power to a first type of wireless power receiving coil using vertical components of the magnetic field generated by the circular coil. The control circuitry can activate the rectangular coils to transmit wireless power to a second type of wireless power receiving coil using horizontal components of the magnetic field generated by the rectangular coils. The circular and rectangular coils wirelessly charge the power receiving device while located at the same position on the charging surface, regardless of the type of wireless power receiving coil that is used.

Wireless power transmitting devices

A wireless power system has a wireless power transmitting device such as a charging mat with a charging surface and a wireless power receiving device that receives wireless power from coils overlapped by the charging surface. The wireless power transmitting device receives load current and load voltage measurements from the wireless power receiving device and uses this information to produce one or more load lines. The load lines may form a family of load lines each associated with a different respective duty cycle used by inverter circuitry in the wireless power transmitting device in transmitting wireless power signals using the coils. The control circuitry can determine whether the wireless power receiving device has moved by comparing current and voltage information from the wireless power receiving device to the family of load lines and can take appropriate action such as measuring coil inductances for use in subsequent coil selection operations.

Wireless power system with device movement detection

A wireless power transmission system has a wireless power receiving device that can be charged using multiple different types of wireless power transmitting devices. The different types of wireless power transmitting devices have power transmitting coils that exhibit different levels of magnetic coupling with the power receiving coil of the wireless power receiving device. The wireless power receiving device may include capacitors, resistors, and/or other loading circuits that can be independently switched into use depending on the level of magnetic coupling that is detected, on a rectified voltage level, on the size of the output load, and/or on information conveyed during handshaking operations to present a desired impedance adjustment at the power receiving coil so that data signal can be properly conveyed between the power receiving device and the power transmitting device.

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San Jose, CA, United States of America

Dmitry Berdnikov