Abstract: A method for determining a quality factor of a wireless charger is disclosed. The wireless charger includes an inverter, a filter, and a resonant tank circuit. The inverter receives a supply voltage and generates a PWM signal at a first node and a second node. The filter connects to the first and second nodes of the inverter to receive the PWM signal, and generates a filtered signal at a first terminal and a second terminal of a capacitor. The resonant tank circuit connects to the first and second terminals of the capacitor of the filter to receive the filtered signal, and provides wireless power at an inductor coil to a receiver. The method includes: issuing a current pulse to the resonant tank circuit; and in a Q-factor determination phase of the wireless charger, connecting the resonant tank circuit and only the capacitor of the filter in a resonance network.

Abstract: A wireless charging transmitter, controller and system are disclosed. The transmitter has a full-bridge inverter having two full-bridge output nodes, a resonant circuit comprising a series arrangement of a transmitter inductor and a first capacitor, and a second capacitor in parallel with the series arrangement, a PI-filter coupled between the second capacitor and the full-bridge inverter; wherein the controller is configured to measure a Q-factor of the resonant circuit by: controlling the full-bridge inverter to connect an input voltage supply to the PI-filter to supply an excitation pulse to the resonant circuit; controlling the full-bridge inverter to disconnect the input voltage supply and initiate a resonance in the resonant circuit; controlling a switch in the full-bridge inverter to provide an reference ground to a first terminal of the transmitter inductor; and measuring a decay of the voltage at a second terminal of the transmitter inductor.

Abstract: A wireless power transmitter to wirelessly transmit power applies a current or voltage to a transmitter coil based on an indication of coupling being in a predetermined range. The current or voltage which is applied causes the transmitter coil to transmit a high power (HP) DPING. A response to the HP DPING indicates that a wireless power receiver is located on a charging surface and a power signal is then transmitted to the wireless power receiver to charge or power an electronic device coupled to the wireless power receiver. Use of HP DPING improves the wireless power transmission performance including transmission area and interoperability of wireless power transmitters with low coupling to wireless power receivers.

Abstract: A wireless power transmitter to wirelessly transmit power applies a current or voltage to a transmitter coil based on an indication of coupling being in a predetermined range. The current or voltage which is applied causes the transmitter coil to transmit a high power (HP) DPING. A response to the HP DPING indicates that a wireless power receiver is located on a charging surface and a power signal is then transmitted to the wireless power receiver to charge or power an electronic device coupled to the wireless power receiver. Use of HP DPING improves the wireless power transmission performance including transmission area and interoperability of wireless power transmitters with low coupling to wireless power receivers.

Abstract: A method of compensating for temperature dependent Q factor variations in a wireless charger includes receiving, by the wireless charger, a reference Q factor value from a device to be charged. The method also includes the wireless charger determining a Q factor threshold value from the reference Q factor. The method further includes the wireless charger measuring a Q factor associated with a transmit coil of the wireless charger. The method also includes determining a temperature value. The method further includes applying a temperature compensation calculation to the measured Q factor using the temperature value to produce a temperature compensated Q factor. The method also includes comparing the temperature compensated Q factor with the Q factor threshold value. The method may also include compensation for temperature dependent internal power loss values.

Abstract: A wireless charger includes a plurality of charging units for charging wirelessly chargeable devices. Each charging unit includes one or more transmit coils for producing a wireless charging signal. Each charging unit also includes a driver circuit for driving the one or more transmit coils. The driver circuit is switchable according to a charging PWM duty cycle of that charging unit. Each charging unit is operable to perform a Q factor measurement by injecting excitation energy into the one or more transmit coils of that charging unit to produce a free resonance signal, and measuring a decay rate of the free resonance signal. Each charging unit is operable to alter its charging PWM duty cycle during a time window in which another charging unit of the wireless charger is performing a Q factor measurement.

Abstract: A wireless charging transmitter includes first and second input terminals for receiving an input voltage from a power source, a coil, an inverter having first and second inverter input terminals coupled to the first and second input terminals respectively, and first and second inverter output terminals for providing an output voltage to the coil. A control system is configured to monitor a voltage between the first and second input terminals, and control the inverter to adjust the output voltage, based on an offset between the monitored voltage and a target voltage, to at least partially compensate the offset. The wireless charging transmitter may further include an ideal diode coupled between one of the input terminals and the inverter.

Abstract: A method of compensating for temperature dependent Q factor variations in a wireless charger includes receiving, by the wireless charger, a reference Q factor value from a device to be charged. The method also includes the wireless charger determining a Q factor threshold value from the reference Q factor. The method further includes the wireless charger measuring a Q factor associated with a transmit coil of the wireless charger. The method also includes determining a temperature value. The method further includes applying a temperature compensation calculation to the measured Q factor using the temperature value to produce a temperature compensated Q factor. The method also includes comparing the temperature compensated Q factor with the Q factor threshold value. The method may also include compensation for temperature dependent internal power loss values.

Abstract: A wireless charger includes a plurality of charging units for charging wirelessly chargeable devices. Each charging unit includes one or more transmit coils for producing a wireless charging signal. Each charging unit also includes a driver circuit for driving the one or more transmit coils. The driver circuit is switchable according to a charging PWM duty cycle of that charging unit. Each charging unit is operable to perform a Q factor measurement by injecting excitation energy into the one or more transmit coils of that charging unit to produce a free resonance signal, and measuring a decay rate of the free resonance signal. Each charging unit is operable to alter its charging PWM duty cycle during a time window in which another charging unit of the wireless charger is performing a Q factor measurement.

Abstract: A wireless charger includes a rectifier, a first filter that includes an inductor, a resonant tank circuit, and a second filter that includes a switch. The rectifier receives a drive signal from a voltage supply and generates a rectified voltage signal. The rectified voltage signal is filtered by the first filter and the filtered signal is provided to the tank circuit, which resonates to provide power wirelessly to a receiver. The switch of the second filter is connected in parallel with the inductor of the first filter. The switch is closed in order to bypass the inductor during a detection phase in which the wireless charger determines a quality factor of the tank circuit.

Abstract: A wireless charger includes multiple transmitter coils, first and second drivers, and a controller. The transmitter coils are arranged close to and/or overlap with each other. The first driver is coupled with at least one of the transmitter coils to drive the transmitter coil to communicate with and/or provide power over a first channel to receiver devices. The second driver is coupled with at least another one of the transmitter coils to drive the transmitter coil to communicate with and/or provide power over a second channel to receiver devices. The controller is coupled with the first and second drivers and enables only one of the first and second drivers at a time during a first stage.

Abstract: A method for determining a quality factor of a wireless charger is disclosed. The wireless charger includes an inverter, a filter, and a resonant tank circuit. The inverter receives a supply voltage and generates a PWM signal at a first node and a second node. The filter connects to the first and second nodes of the inverter to receive the PWM signal, and generates a filtered signal at a first terminal and a second terminal of a capacitor. The resonant tank circuit connects to the first and second terminals of the capacitor of the filter to receive the filtered signal, and provides wireless power at an inductor coil to a receiver. The method includes: issuing a current pulse to the resonant tank circuit; and in a Q-factor determination phase of the wireless charger, connecting the resonant tank circuit and only the capacitor of the filter in a resonance network.

Abstract: A wireless charger includes multiple transmitter coils, first and second drivers, and a controller. The transmitter coils are arranged close to and/or overlap with each other. The first driver is coupled with at least one of the transmitter coils to drive the transmitter coil to communicate with and/or provide power over a first channel to receiver devices. The second driver is coupled with at least another one of the transmitter coils to drive the transmitter coil to communicate with and/or provide power over a second channel to receiver devices. The controller is coupled with the first and second drivers and enables only one of the first and second drivers at a time during a first stage.

Abstract: A two-stage wireless power transfer system has three distinct components. A first component has a first-stage wireless power transmitter (TX). A second component has a first-stage wireless power receiver (RX) hardwired to a second-stage wireless power transmitter. A third component, which may be a rechargeable, battery-powered device like a cell phone, has a second-stage wireless power receiver. The first stage has TX and RX inductor coils that are substantially larger than the TX and RX coils of the second stage. A Z-gap between the first and second components can be relatively large, while still achieving relatively high overall power transfer efficiency as long as the Z-gap between the second and third components is relatively small.

Abstract: In a wireless charging system, a power-transmitting node (TX) has a power transmitter for transmitting power wirelessly to a power-receiving node (RX), a sampling and sensing circuit, a processor, and a signal receiver for receiving signals from the RX. The processor detects the presence of a foreign object (FO) during a power-transfer session using Quality Factor (QF) values. Estimated QF parameters are determined via exponential curve fitting using peak values of a damped sinusoidal waveform generated by a resonant circuit. Then the estimated parameters in the exponential curve are used to calculate the QF, which provides a robust measurement result even in a noisy environment.

Abstract: A wireless charging system (transmitter) has multiple transmit coils that allows for multiple receiver devices (receivers), such as cell phones, to be charged simultaneously. The receivers send data packets that include a receiver ID to the transmitter so that one of the transmitter coils can be paired with a respective one of the receivers. The transmitter can then distinguish between the communications with the receivers using the IDs such that communications with receivers connected with adjacent ones of the transmitter coils do not interfere with each other.

Abstract: A wireless charger includes a rectifier, a first filter that includes an inductor, a resonant tank circuit, and a second filter that includes a switch. The rectifier receives a drive signal from a voltage supply and generates a rectified voltage signal. The rectified voltage signal is filtered by the first filter and the filtered signal is provided to the tank circuit, which resonates to provide power wirelessly to a receiver. The switch of the second filter is connected in parallel with the inductor of the first filter. The switch is closed in order to bypass the inductor during a detection phase in which the wireless charger determines a quality factor of the tank circuit.

Abstract: In a wireless charging system, a power-transmitting node (TX) has a power transmitter for transmitting power wirelessly to a power-receiving node (RX), a sampling and sensing circuit, a processor, and a signal receiver for receiving signals from the RX. The processor detects the presence of a foreign object (FO) during a power-transfer session using Quality Factor (QF) values. Estimated QF parameters are determined via exponential curve fitting using peak values of a damped sinusoidal waveform generated by a resonant circuit. Then the estimated parameters in the exponential curve are used to calculate the QF, which provides a robust measurement result even in a noisy environment.

Abstract: A wireless charging system (transmitter) has multiple transmit coils that allows for multiple receiver devices (receivers), such as cell phones, to be charged simultaneously. The receivers send data packets that include a receiver ID to the transmitter so that one of the transmitter coils can be paired with a respective one of the receivers. The transmitter can then distinguish between the communications with the receivers using the IDs such that communications with receivers connected with adjacent ones of the transmitter coils do not interfere with each other.