Operating frequency based power level altering in extended range wireless power transmitters
A power transmitter for wireless power transfer includes a control and communications unit configured to provide power control signals to control a power level of a power signal configured for transmission to a power receiver and including a pulse width modulation (PWM) signal generator for determining and selecting the operating frequency from the operating frequency range. The power transmitter further includes an inverter circuit configured to receive a direct current (DC) power and convert the input power to a power signal, coil configured to transmit the power signal to a power receiver, the coil formed of wound Litz wire and including at least one layer, the coil defining, at least, a top face, and a shielding comprising a ferrite core and defining a cavity, the cavity configured such that the ferrite core substantially surrounds all but the top face of the coil.
1 . A wireless power transfer system comprising:
a power receiver that (i) is configured to send a power request signal to a power transmitter and (ii) comprises a receiver coil configured to receive a wireless power transmission from a transmitter coil of the power transmitter;
the power transmitter comprising:
a power input in operative association with an external power supply and configured to receive a direct current (“DC”) input power from the external power supply;
an inverter circuit configured to (i) receive the DC input power via the power input in response to a power control signal that is configured to control input from the external power supply, (ii) receive a driving signal that is configured to generate an alternating current (“AC”) power signal for transmitting wireless power, and (iii) convert the DC input power to the AC power signal, based on the driving signal; and
the transmitter coil configured to, based on the AC power signal, transmit the wireless power transmission to the receiver coil of the power receiver; and
a transmitter controller comprising:
at least one processor;
at least one non-transitory machine-readable medium; and
program instructions provisioned on the at least one non-transitory machine-readable medium that, when executed by the at least one processor, cause the transmitter controller to:
receive the power request signal from the power receiver;
determine a power requirement for the wireless power transmission based on the power request signal;
determine the power control signal based on the power requirement, the power control signal configured to instruct the external power supply to select a DC voltage for the DC input power from a set of DC voltage levels, the set of DC voltage levels comprising a first DC voltage level associated with a first AC power signal level and a second DC voltage level associated with a second AC power signal level;
determine an operating frequency from an operating frequency range for the driving signal, the operating frequency associated with a third AC power signal level that is greater than the first AC power signal level and less than the second AC power signal level;
generate the driving signal based on the operating frequency; and
provide the power control signal to the external power supply.
2 . The wireless power transfer system of claim 1 , wherein the operating frequency range is about 87 kilohertz (“kHz”) to about 205 kHz.
3 . The wireless power transfer system of claim 1 , wherein the set of DC voltage levels include at least two of 5 Volts (“V”), 9 V, 15 V, or 20 V.
4 . The wireless power transfer system of claim 1 , wherein the power request signal is based on one or more of (i) a current charge level of a load associated with the power receiver, (ii) a voltage at a rectifier of the power receiver, (iii) a load resistance associated with the power receiver, or (iv) combinations thereof.
5 . The wireless power transfer system of claim 1 , wherein the program instructions that, when executed by the at least one processor, cause the transmitter controller to receive a power request signal from the power receiver comprises program instructions that, when executed by the at least one processor, cause the transmitter controller to:
when the transmitter coil and the receiver coil are coupled:
detect a plurality of alterations in the wireless power transmission as in-band signals of the wireless power transmission, and
decode the power request signal from the plurality of alterations in the wireless power transmission.
6 . The wireless power transfer system of claim 1 , wherein the driving signal is a pulse-width modulation (“PWM”) driving signal, and
wherein the transmitter controller further comprises a PWM generator configured to receive the driving signal and output the driving signal to the inverter circuit.
7 . The wireless power transfer system of claim 1 , wherein the power input is configured to receive the DC input power via one or more of a Universal Serial Bus (USB) connection, a Lightning power connection, a Qualcomm Quick Charge based connection, a USB Type-C (USB-C) type connection, a USB Power Delivery (USB-PD) type connection, a Mini-USB type connection, or combinations thereof.
8 . The wireless power transfer system of claim 1 , wherein the at least one processor comprises at least one first processor, wherein the at least one non-transitory machine-readable medium comprises at least one first non-transitory machine-readable medium, wherein the program instructions stored on the at least one non-transitory machine-readable medium comprise first program instructions stored on the at least one first non-transitory machine-readable medium, and
the wireless power transfer system further comprising the external power supply, which is configured to generate the DC input power, the external power supply comprising:
a voltage regulator, and
a power supply controller comprising:
at least one second processor,
at least one second non-transitory machine-readable medium, and
second program instructions stored on the at least one second non-transitory machine-readable medium, that, when executed by the at least one second processor, cause the power supply controller to:
receive the power control signal,
generate voltage regulation instructions for altering the DC voltage for DC input power signals based on the power control signal,
provide the voltage regulation instructions to the voltage regulator and thereby cause the voltage regulator to output the DC input power signals.
9 . The wireless power transfer system of claim 1 , wherein the power transmitter is operatively associated with a base station.
10 . The wireless power transfer system of claim 1 , wherein the power receiver is operatively associated with a wearable electronic device.