Nxp Usa, Inc.

Freescale Semiconductor,inc.

Dechang Wang

Li Wang

Huan Mao

Dengyu Jiang

Xiang Gao

Wei Cao

Yong Wang

Changhao Shi

Ruyang Sheng

Fei Chen

Ping Zhao

Yonggang Chen

Lingling Wang

Zhendong Fei

Rui Lv

Yangjie Zhang

Changchao Shi

Jan Horak

Transferring wireless power using a multiple pulse width modulation M-PWM driver signal includes generating the multiple PWM driver signal such that the pulse width varies in accordance with the magnitude of a periodic modulating curve. The M-PWM driver signal adjacent a zero-crossing of the periodic modulating wave is modified by reducing an interval between the zero-crossing and at least one pulse of the M-PWM driver signal closest to the zero-crossing. The modified M-PWM driver signal is used to open and close a switch in a wireless power transfer charging circuit.

Multiple and sinusoidal pulse width modulation for wireless charging

Power transmission associated with wireless charging of a battery of an electronic device or powering of the electronic device comprises determining a power loss associated with transmitting a power signal having a transmitted power from the wireless power transmitter to a wireless power receiver. A closed loop power loss control based on the power loss is performed which comprises outputting a target transmit power to meet a power loss limit. The power signal having the target transmit power is wirelessly transmitted to the wireless power receiver to charge the battery of the electronic device or power the electronic device and balance charging performance and safety.

Closed loop power loss control of wireless power transmission, and methods for wireless power transmission

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.

Method for determining a quality factor and wireless charger

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.

Wireless charging method, device and system

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.

Wireless charger, system and method

Apparatus and methods of providing digital varying output, such as sinusoidal, pulse width modulation, SPWM, control for an inverter comprising at least a first switch and a second switch are disclosed. The method comprising: generating a first binary control signal at a system modulation frequency; generating a second binary control signal at an M-times higher carrier frequency; wherein generating the second binary control signal comprises: providing a periodic counter having a K-times higher reset frequency; calculating M switch-off moments; determining for each, a corresponding switch-off counter value and a corresponding counter sequence value; storing each switch-off counter value in a respective memory location corresponding to the respective counter sequence and dummy values in the remaining memory locations; and sequentially and periodically transferring the contents of the memory locations to at least one PWM value register.

Apparatus and methods for varying output pulse-width modulation (PWM) control of an inverter

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.

Q-factor determination in wireless charging system having complex resonant circuit

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.

Multi-coil wireless charger

A wireless power receiver has over-voltage protection (OVP) circuitry that performs different techniques for different over-voltage conditions. The OVP circuitry includes controllable resistive clamp circuitry (a resistor in series with a resistor control switch) and controllable capacitive clamp circuitry (a capacitor in series with a capacitor control switch). Based on an output-based feedback signal and a reference signal, comparison circuitry generates comparison signals, based on which a controller selectively enables (i) the resistive clamp circuitry intermittently for a relatively low over-voltage condition and continuously for a higher over-voltage condition and (ii) the capacitive clamp circuit to detune the receiver, both in order to decrease the rectified output voltage.

Overvoltage protection circuit for wireless power receiver

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.

Q-factor determination for foreign object detection circuit in wireless charging system

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.

Method of pairing receiver with wireless charger transmitter

An apparatus for detecting disconnection of a secondary side of a current transformer includes a sampling circuit coupled to the secondary side of the current transformer that samples signals from the secondary side of the current transformer. A pull-up circuit is switchably coupled to the sampling circuit in response to a coupling signal in a diagnostic phase. A processor is coupled to the sampling circuit for receiving sampled signals from the sampling circuit. The processor extracts corresponding signal information from the sampled signals and stores the extracted signal information in a memory. The extracted signal information corresponds to statuses that the secondary side of the current transformer is connected or disconnected to a load. A detector is coupled to the processor and the memory, and accesses the memory using the signal information of the sampled signals.

Apparatus and method for detecting disconnection in secondary side of current transformer

A bridgeless power factor correction (PFC) circuit has first and second nodes, and first and second current paths connected between the first and second nodes. The first current path includes a first semiconductor device and a first switch element, and the second current path includes a second semiconductor device and a second switch element. One of the first and the second current paths further includes first and second sensing elements that are oppositely connected in series.

Power factor correction circuit

A wireless transmitter wirelessly charges/powers a wireless receiver. The transmitter performs an analog ping to tentatively detect a device. During an energizing phase of the analog ping, the transmitter applies power pulses to a resonant circuit within the transmitter, where, after application of the power pulses, the resonant circuit enters a free-resonance state of a resonating phase of the analog ping that follows the energizing phase. During the resonating phase, while the resonant circuit is in the free-resonance state, the transmitter samples voltage within the resonant circuit to generate one or more voltage-level samples. The transmitter processes the voltage-level samples to tentatively detect the device. If a device is tentatively detected then the transmitter performs a digital ping to definitively determine whether the device is present. If definitively detected then the transmitter wirelessly charges/powers the wireless receiver.

Free-resonance analog ping for wireless power transmission

A wireless charging system has a transmitter and a receiver. The transmitter has (i) a TX coil that wirelessly transfers power to the receiver and (ii) TX circuitry that powers the TX coil and detects receiver removal by comparing TX input power and TX power loss. The TX circuitry can determine (1) TX input power as the product of sampled TX input current and voltage and (2) TX power loss using a mapping based on sampled TX coil current. When the receiver is present, the difference between TX input power and TX power loss has a first value and when the receiver is removed, the difference has a second, lesser value. The transmitter detects removal of the receiver by determining when the difference decreases below a specified threshold level. By frequently generating and analyzing the difference, the transmitter can quickly detect receiver removal and safely power down the TX coil.

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Suzhou, China

Dechang Wang