Abstract: An electronic device in a wireless power system may be operable with a removable accessory such as a case. The device may convey wireless power to, from, or through the case while the device is coupled to the case. The device may have coplanar power transmitting and power receiving coils. The removable accessory may have an embedded switchable ferrimagnetic core and a coil that overlaps the switchable ferrimagnetic core. The switchable ferrimagnetic core may be operable in a first state where the switchable ferrimagnetic core is unsaturated. The switchable ferrimagnetic core may be operable in a second state where the switchable ferrimagnetic core is saturated by a magnetic field from a permanent magnet in a wireless power transmitting device. In the second state, the switchable ferrimagnetic core may have a lower magnetic permeability and higher magnetic reluctance than in the first state.

Abstract: An accessory for improving wireless power transfer efficiency in a wireless power transfer system can include a magnetic (e.g., ferrite) core dimensioned and positioned so as to reduce flux coupling from the PTx winding into friendly metal of the PRx and/or to enhance flux coupling from the PTx winding to the PRx winding. The core may define an aperture corresponding to an outer dimension (e.g., outer diameter) of the PRx winding. The core may further have an outer dimension selected to intercept sufficient flux to reduce flux coupling into the friendly metal of the PRx, such as an outer dimension corresponding to an outer dimension (e.g., outer diameter) of the PTx winding. The accessory may be a case for the PRx device or may be configured to be affixed to the face of the PTx device and may also include one or more alignment fixtures.

Abstract: A switched capacitor converter can include a switched capacitor stage comprising a flying capacitor and a ladder of three switching devices. A first switching device can be connected between a DC input of the switched capacitor converter and an AC bus. A second switching device is connected between the DC input and a third switching device. The third switching device can be connected between the second switching device and ground. The flying capacitor can be connected between the AC bus and a junction of the second switching device and the third switching device. The switched capacitor converter can further include an inverter stage having an input coupled to the AC bus and an output that delivers an AC voltage.

Abstract: A method of modeling a wireless power transfer system can include constructing a loss-split circuit model of the wireless power transfer system. The loss-split circuit model can include a plurality of resistance values corresponding to power losses in selected components of the power system. The method can further include performing a plurality of finite element analyses to determine the plurality of resistor values. The one or more resistance values can correspond to power losses associated with one or more of: a transmitter coil, a receiver coil, friendly metal associated with a transmitter, friendly metal associated with a receiver, and a foreign object.

Abstract: Electronic apparatuses according to embodiments of the present technology may include an electronic device a first surface and a second surface opposite the first. The electronic device may include a battery and a wireless charging coil within an interior volume of the device. The electronic device may include a first magnetic conductor and positioned between the battery and the wireless charging coil. The electronic device may also include an integrated circuit coupled with the battery and the wireless charging coil. The apparatuses may include a case extending about the electronic device. The case may be characterized by a first surface and a second surface. The case may be characterized by a thickness between the first surface of the case and the second surface of the case. The case may include a second magnetic conductor incorporated within the thickness of the case at the second surface of the case.

Abstract: An electronic device (that is capable of both transmitting and receiving wireless power) may be physically and inductively coupled to a removable accessory (that only receives wireless power). The electronic device and removable accessory may optionally be placed on a power transmitting device. In response to the electronic device and removable accessory being placed on a wireless power transmitting device, the electronic device may switch from a power transmitting mode (in which the electronic device transmits wireless power to the removable accessory) to a power receiving mode (in which the electronic device receives wireless power from the wireless power transmitting device). To ensure the electronic device detects the wireless power transmitting device and switches to the power receiving mode in this scenario, the electronic device may transmit wireless power in bursts separated by sleep periods while in the power transmitting mode.

Abstract: Electronic apparatuses according to embodiments of the present technology may include an electronic device a first surface and a second surface opposite the first. The electronic device may include a battery and a wireless charging coil within an interior volume of the device. The electronic device may include a first magnetic conductor and positioned between the battery and the wireless charging coil. The electronic device may also include an integrated circuit coupled with the battery and the wireless charging coil. The apparatuses may include a case extending about the electronic device. The case may be characterized by a first surface and a second surface. The case may be characterized by a thickness between the first surface of the case and the second surface of the case. The case may include a second magnetic conductor incorporated within the thickness of the case at the second surface of the case.

Abstract: An electronic device (that is capable of both transmitting and receiving wireless power) may be physically and inductively coupled to a removable accessory (that only receives wireless power). The electronic device and removable accessory may optionally be placed on a power transmitting device. In response to the electronic device and removable accessory being placed on a wireless power transmitting device, the electronic device may switch from a power transmitting mode (in which the electronic device transmits wireless power to the removable accessory) to a power receiving mode (in which the electronic device receives wireless power from the wireless power transmitting device). To ensure the electronic device detects the wireless power transmitting device and switches to the power receiving mode in this scenario, the electronic device may transmit wireless power in bursts separated by sleep periods while in the power transmitting mode.

Abstract: An electronic device in a wireless power system may be operable with a removable accessory such as a case. The device may convey wireless power to, from, or through the case while the device is coupled to the case. The device may have coplanar power transmitting and power receiving coils. The removable accessory may have an embedded switchable ferrimagnetic core and a coil that overlaps the switchable ferrimagnetic core. The switchable ferrimagnetic core may be operable in a first state where the switchable ferrimagnetic core is unsaturated. The switchable ferrimagnetic core may be operable in a second state where the switchable ferrimagnetic core is saturated by a magnetic field from a permanent magnet in a wireless power transmitting device. In the second state, the switchable ferrimagnetic core may have a lower magnetic permeability and higher magnetic reluctance than in the first state.

Abstract: A wireless charging mat and method of operating the same. The wireless charging mat includes a detection system configured to determine a location and an orientation of an electronic device on the wireless charging mat. The location and orientation are determined based on detected locations of one or more structural features of the electronic device. The wireless charging mat is operated according to the detected location and orientation.

Abstract: A wireless power relay can include a first wireless power receiver (Rx1) configured to receive power from a first wireless power transmitter (Tx1) in another device and a second wireless power transmitter (Tx2) configured to deliver power to a second wireless power receiver (Rx2) in another device. Rx1 may be configured to communicate with Tx1 via a first communication link, and the Tx2 may be configured to receive communication from Rx2 via a second communication link, both employing modulation of the wireless power signal. The relay may further include a power converter with its input coupled to Rx1 and its output coupled to Tx2 and a constant power controller configured to isolate modulated communication between the communication links. Additionally or alternatively, the relay may include circuitry configured to introduce a jamming signal preventing Tx1 from detecting and improperly interpreting signals from the second communications link.

Abstract: An electronic device in a wireless power system may be operable with a removable accessory such as a case. The device may convey wireless power to, from, or through the case while the device is coupled to the case. The device may have coplanar power transmitting and power receiving coils. The removable accessory may have an embedded switchable ferrimagnetic core and a coil that overlaps the switchable ferrimagnetic core. The switchable ferrimagnetic core may be operable in a first state where the switchable ferrimagnetic core is unsaturated. The switchable ferrimagnetic core may be operable in a second state where the switchable ferrimagnetic core is saturated by a magnetic field from a permanent magnet in a wireless power transmitting device. In the second state, the switchable ferrimagnetic core may have a lower magnetic permeability and higher magnetic reluctance than in the first state.

Abstract: A wireless charging mat and method of operating the same. The wireless charging mat includes a detection system configured to determine a location and an orientation of an electronic device on the wireless charging mat. The location and orientation are determined based on detected locations of one or more structural features of the electronic device. The wireless charging mat is operated according to the detected location and orientation.

Abstract: A method of adaptively controlling dead time between turn off of a first switching device of an inverter and turn on of a second switching device of the inverter that is a counterpart of the first switching device can include: monitoring a plurality of switching events of at least one of the first and second switching devices, storing for each monitored switching event an indication whether a dead time associated therewith permitted optimal switching, and adaptively controlling the dead time responsive to the stored indications. Monitoring a plurality of switching events of at least one of the first and second switching devices can further include sampling an output voltage of the inverter and comparing the sampled output voltage to one of a high reference voltage corresponding to a high inverter rail voltage and a low reference voltage corresponding to a low inverter rail voltage.

Abstract: A wireless power transfer system can include an electronic device including a first wireless power transfer coil and wireless power transfer circuitry coupled to the wireless power transfer coil. The wireless power transfer circuitry can be capable of receiving power and transmitting power wirelessly via the first wireless power transfer coil. The system can further include an accessory device including a second wireless power transfer coil, a rectifier coupled to the second wireless power transfer coil, and an energy storage device coupled to the rectifier by a regulator circuit. The wireless power transfer circuitry can operate in a pulsed or burst wireless power transfer mode to deliver power to the accessory device.

Abstract: A transmitter device is configured to transfer energy to multiple receiver devices. The transmitter device includes multiple transmitter coils, and a shared power converter is coupled to each transmitter coil. The shared power converter includes a leading half bridge and multiple trailing half bridges. Each transmitter coil is coupled between the leading half bridge and a respective one of the trailing half bridges. The shared power converter is dynamically configurable in that the leading half bridge may be coupled to multiple trailing half bridges when energy is to be transferred wirelessly to two or more receiver devices. The leading half bridge simultaneously operates with each trailing half bridge as an independent full-bridge phase shift inverter. A signal supplied to each transmitter coil is independently regulated by controlling a phase shift of a respective trailing half bridge with respect to the leading half bridge.

Abstract: A device in a wireless power system may be operable with a removable accessory such as a case. The device may transmit or receive wireless power through the case while the electronic device is coupled to the case. The case may have a folio shape with a front cover portion that covers the display of the electronic device. The case may have an embedded ferrimagnetic core that relays magnetic flux during wireless power transfer operations. Magnetic alignment structures in the case may position the ferrimagnetic core in the case in a high magnetic flux density region between the power transmitting device and the power receiving device. The ferrimagnetic core relays the magnetic flux between a transmitting coil in the power transmitting device and a receiving coil in the power receiving device. The ferrimagnetic core may be formed in a front portion, a sidewall, or a rear wall of a case.

Abstract: A wireless power system has a wireless power transmitting device and multiple wireless power receiving devices. The wireless power transmitting device may have a foldable housing. The wireless power transmitting device has wireless power coils that are used in transmitting wireless power to electronic devices such as cellular telephones, wristwatches, ear buds battery cases, ear buds, computer styluses, and other electronic devices. A rectifier can be coupled to a wireless power coil. In a first mode the coil transmits wireless power to a cellular telephone or other device. In a second mode, the coil is used in receiving wireless power from the cellular telephone or other device. The received wireless power can be retransmitted to other devices.

Abstract: Electronic apparatuses according to embodiments of the present technology may include an enclosure having a lid. The enclosure may define a first cavity and a second cavity, and may include an enclosure battery. The apparatuses may include a first enclosure wireless charging coil extending about the first cavity. The apparatuses may include a second enclosure wireless charging coil extending about the second cavity. The apparatuses may include a first earbud having a first earbud battery and a first earbud wireless charging coil operably coupleable with the first enclosure wireless charging coil for wireless charging of the first earbud battery. The apparatuses may include a second earbud having a second earbud battery and a second earbud wireless charging coil operably coupleable with the second enclosure wireless charging coil for wireless charging of the second earbud battery.

Abstract: A method of modeling a wireless power transfer system can include constructing a loss-split circuit model of the wireless power transfer system. The loss-split circuit model can include a plurality of resistance values corresponding to power losses in selected components of the power system. The method can further include performing a plurality of finite element analyses to determine the plurality of resistor values. The one or more resistance values can correspond to power losses associated with one or more of: a transmitter coil, a receiver coil, friendly metal associated with a transmitter, friendly metal associated with a receiver, and a foreign object.