Abstract: A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to the wireless power receiving device. The wireless power transmitting device determines whether an external object is present. The external object may be a foreign object such as a coin or paperclip or may be a wireless power receiving device. External objects are detected using quality-factor measurements. Wireless communications are used to discriminate between foreign objects and wireless power receiving devices. Quality factor measurements may be compensated for aging and temperature effects using temperature measurements and compensation factors based on frequency and measured resistance.

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 wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to the wireless power receiving device. The wireless power transmitting device determines whether an external object is present. The external object may be a foreign object such as a coin or paperclip or may be a wireless power receiving device. External objects are detected using quality-factor measurements. Wireless communications are used to discriminate between foreign objects and wireless power receiving devices. Quality factor measurements may be compensated for aging and temperature effects using temperature measurements and compensation factors based on frequency and measured resistance.

Abstract: Transmitters and/or receivers in a wireless power transfer system predict power losses to account for presence of foreign objects.

Abstract: A wireless power transmitter can include a coil, an inverter coupled to the coil, and control circuitry coupled to the inverter that, responsive to receiving a burst request pulse from a wireless power receiver, initiates inverter operation, driving the coil and powering the receiver. The control circuitry can operate inverter switches so bandwidth of the wireless power transfer signal falls within a specified range by: (a) extending a minimum on time of the switches, (b) modifying pulse width modulation (PWM) drive signals supplied to the switches to shape a coil current burst envelope, and/or (c) modifying PWM signal amplitude supplied to the switches. Modifying the PWM drive signals can include using a symmetrical PWM scheme in which the positive and negative pulses are symmetrical in width on a cycle-by-cycle basis or using a complementary PWM scheme in which the positive and negative pulse widths are complementary on a cycle-by-cycle basis.

Abstract: A wireless power transfer device can include a coil that couples to a corresponding coil of a counterpart device to facilitate wireless power transfer, a power converter coupled to the coil, and controller and communication circuitry that monitors one or more observable parameters associated with the wireless power transfer to detect a presence of a foreign object that is not the counterpart device and controls the power converter responsive to detection of the foreign object. The controller and communication circuitry can perform foreign object detection based on power accounting that includes estimating friendly metal losses associated with the counterpart device. The controller and communication circuitry can interrogate a machine readable tag associated with a case of the counterpart device and can receive from the machine readable tag information about the presence or properties of the case. The machine readable tag can be an NFC tag.

Abstract: A wireless power transfer device can include a coil that couples to a corresponding coil of a counterpart device to facilitate wireless power transfer, a power converter coupled to the coil, and controller and communication circuitry that monitors one or more observable parameters associated with the wireless power transfer to detect a presence of a foreign object that is not the counterpart device and control the power converter responsive to detection of a foreign object. The controller and communication circuitry can perform foreign object detection based on power accounting that includes estimating friendly metal losses associated with the counterpart device. The controller and communication circuitry can receive from the counterpart device friendly metal loss modeling parameters associated with the counterpart device, the modeling parameters including one or more coefficients relating to a wireless power transfer current and one or more coefficients relating to a wireless power transfer voltage.

Abstract: A wireless charging system having a power transmitter may wirelessly transfer power to a power receiver. Shield saturation, such as saturation of a ferrite structure, in the wireless power receiver may occur under some operating conditions. Saturation can lead to disruptive oscillations in power transfer. The power transmitting may include control circuitry for detecting and mitigating saturation.

Abstract: A wireless power transfer device can include a coil that couples to a corresponding coil of a counterpart device to facilitate wireless power transfer, a power converter coupled to the coil, and controller and communication circuitry that monitors one or more observable parameters associated with the wireless power transfer to detect a presence of a foreign object that is not the counterpart device and control the power converter responsive to detection of a foreign object. The controller and communication circuitry can perform foreign object detection based on power accounting that includes estimating friendly metal losses associated with the counterpart device. The controller and communication circuitry can receive from the counterpart device friendly metal loss modeling parameters associated with the counterpart device, the modeling parameters including one or more coefficients relating to a wireless power transfer current and one or more coefficients relating to a wireless power transfer voltage.

Abstract: A wireless charging system having a power transmitter may wirelessly transfer power to a power receiver. Shield saturation, such as saturation of a ferrite structure, in the wireless power receiver may occur under some operating conditions. Saturation can lead to disruptive oscillations in power transfer. The power transmitting may include control circuitry for detecting and mitigating saturation.

Abstract: A multi-coil wireless power transfer (WPT) arrangement can include a magnetic core; first and second WPT coils positioned adjacent one another above the magnetic core; a third WPT coil positioned above the first and second wireless power transfer coils; a magnet ring located above the first and second wireless power transfer coils; additional magnetic core material disposed atop the magnetic core and associated with the third WPT coil. The first and second WPT coils can be separated by a separation distance selected to accommodate the additional magnetic core material; and a segmented metallic shield positioned between the magnet ring and the first and second wireless power transfer coils. The additional magnetic core material can include a base portion disposed atop the magnetic core and beneath the third wireless power transfer coil and/or a post portion disposed atop the base portion and within the third wireless power transfer coil.

Abstract: A wireless charging system having a power transmitter may wirelessly transfer power to a power receiver. Shield saturation, such as saturation of a ferrite structure, in the wireless power receiver may occur under some operating conditions. Saturation can lead to disruptive oscillations in power transfer. The power transmitting may include control circuitry for detecting and mitigating saturation.

Abstract: A wireless power transfer device can include a coil that couples to a corresponding coil of a counterpart device to facilitate wireless power transfer, a power converter coupled to the coil, and controller and communication circuitry that monitors one or more observable parameters associated with the wireless power transfer to detect a presence of a foreign object that is not the counterpart device and control the power converter responsive to detection of a foreign object. The controller and communication circuitry can perform foreign object detection based on power accounting that includes estimating friendly metal losses associated with the counterpart device. The controller and communication circuitry can receive from the counterpart device friendly metal loss modeling parameters associated with the counterpart device, the modeling parameters including one or more coefficients relating to a wireless power transfer current and one or more coefficients relating to a wireless power transfer voltage.

Abstract: A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to the wireless power receiving device. The wireless power transmitting device determines whether an external object is present. The external object may be a foreign object such as a coin or paperclip or may be a wireless power receiving device. External objects are detected using quality-factor measurements. Wireless communications are used to discriminate between foreign objects and wireless power receiving devices. Quality factor measurements may be compensated for aging and temperature effects using temperature measurements and compensation factors based on frequency and measured resistance.

Abstract: A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to the wireless power receiving device. The wireless power transmitting device determines whether an external object is present. The external object may be a foreign object such as a coin or paperclip or may be a wireless power receiving device. External objects are detected using quality-factor measurements. Wireless communications are used to discriminate between foreign objects and wireless power receiving devices. Quality factor measurements may be compensated for aging and temperature effects using temperature measurements and compensation factors based on frequency and measured resistance.

Abstract: A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device may include ASK decoding circuitry. An inverter controller may supply control signals to an inverter based on a clock signal. To improve wireless transmission at various frequencies of interest, the clock signal used by the inverter controller may be dithered using a modulating signal. To mitigate bit errors in ASK decoding caused by the dithering of the clock signal in the wireless power transmitting device, ASK communication receiving circuitry in the wireless power transmitting device may receive information regarding the modulating signal used to dither the clock signal. The ASK communication receiving circuitry may receive a clock signal that has been dithered using the modulating signal, dither an analog-to-digital converter sampling rate using the modulating signal, or include notch filtering circuitry with parameters determined based on the modulating signal.

Abstract: A wireless charging system having a power transmitter may wirelessly transfer power to a power receiver. Shield saturation, such as saturation of a ferrite structure, in the wireless power receiver may occur under some operating conditions. Saturation can lead to disruptive oscillations in power transfer. The power transmitting may include control circuitry for detecting and mitigating saturation.

Abstract: A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to the wireless power receiving device. The wireless power transmitting device determines whether an external object is present. The external object may be a foreign object such as a coin or paperclip or may be a wireless power receiving device. External objects are detected using quality-factor measurements. Wireless communications are used to discriminate between foreign objects and wireless power receiving devices. Quality factor measurements may be compensated for aging and temperature effects using temperature measurements and compensation factors based on frequency and measured resistance.

Abstract: A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to the wireless power receiving device. The wireless power transmitting device determines whether an external object is present. The external object may be a foreign object such as a coin or paperclip or may be a wireless power receiving device. External objects are detected using quality-factor measurements. Wireless communications are used to discriminate between foreign objects and wireless power receiving devices. Quality factor measurements may be compensated for aging and temperature effects using temperature measurements and compensation factors based on frequency and measured resistance.

Abstract: A wireless charging system having a power transmitter may wirelessly transfer power to a power receiver. Shield saturation, such as saturation of a ferrite structure, in the wireless power receiver may occur under some operating conditions. Saturation can lead to disruptive oscillations in power transfer. The power transmitting may include control circuitry for detecting and mitigating saturation.