Wireless power transmitters with wide input voltage range and methods of their operation
First Claim
1. A power transmitter for wirelessly charging an electronic device, the power transmitter comprising:
- an input configured to receive a variable DC input voltage;
an inverter coupled to the input to receive the variable DC input voltage, the inverter configured to generate an AC square-wave signal having a duty cycle selected to provide a predetermined equivalent voltage, wherein the inverter is configured to generate the AC square-wave signal with a relatively high duty cycle when a determined magnitude of the variable DC input voltage is relatively low, and the inverter is configured to generate the AC square-wave signal with a relatively low duty cycle when the determined magnitude of the variable DC input voltage is relatively high;
a plurality of primary coils coupled to a matching network to receive a charging signal, the plurality of primary coils configured to be selectable in multiple different coil combinations, each of the multiple different coil combinations including a number of the plurality of primary coils, with at least one of the multiple different coil combinations including more than one of the plurality of primary coils to facilitate transmission with different numbers of primary coils, the plurality of primary coils configured to selectively transmit a power transfer signal to a receiver coil on the electronic device; and
the matching network coupled to the inverter and to the plurality of primary coils, the matching network configured to generate the charging signal from the AC square-wave signal and to provide the charging signal to the plurality of primary coils, the matching network includinga differential input with first and second differential inputs configured to receive the AC square wave signal,a differential output with first and second differential outputs configured to produce the charging signal, anda plurality of switched capacitors that are selectively switched to achieve maximum power transfer efficiency for a selected coil combination used to transmit the power transfer signal, wherein the plurality of switched capacitors are coupled in parallel across the first and second differential inputs, wherein a first number of the plurality of switched capacitors are switched into the matching circuit when a first number of primary coils are included in the selected coil combination, and one or more additional switched capacitors are switched into the matching circuit when a second and larger number of primary coils are included in the selected coil combination.
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Accused Products
Abstract
The embodiments described herein provide a power transmitter for wireless charging of an electronic device and methods of its operation. The power transmitter uses an inverter configured to generate a square wave from a potentially wide ranging DC input voltage. The inverter is configured to generate the square wave with a duty cycle that results in a desired equivalent voltage output, effectively independent of the DC input voltage that is provided. Thus, by generating a square wave with a selectable duty cycle the inverter provides the ability to facilitate wireless power transfer with a wide range of DC input voltages. Furthermore, in some embodiments the power transmitter may provide improved power transfer efficiency using a quasi-resonant phase shift control strategy with adjustable dead time and a matching network that is dynamically selectable to more effectively couple with the transmitter coil combination being used to transmit power to the electronic device.
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Citations
20 Claims
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1. A power transmitter for wirelessly charging an electronic device, the power transmitter comprising:
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an input configured to receive a variable DC input voltage; an inverter coupled to the input to receive the variable DC input voltage, the inverter configured to generate an AC square-wave signal having a duty cycle selected to provide a predetermined equivalent voltage, wherein the inverter is configured to generate the AC square-wave signal with a relatively high duty cycle when a determined magnitude of the variable DC input voltage is relatively low, and the inverter is configured to generate the AC square-wave signal with a relatively low duty cycle when the determined magnitude of the variable DC input voltage is relatively high; a plurality of primary coils coupled to a matching network to receive a charging signal, the plurality of primary coils configured to be selectable in multiple different coil combinations, each of the multiple different coil combinations including a number of the plurality of primary coils, with at least one of the multiple different coil combinations including more than one of the plurality of primary coils to facilitate transmission with different numbers of primary coils, the plurality of primary coils configured to selectively transmit a power transfer signal to a receiver coil on the electronic device; and the matching network coupled to the inverter and to the plurality of primary coils, the matching network configured to generate the charging signal from the AC square-wave signal and to provide the charging signal to the plurality of primary coils, the matching network including a differential input with first and second differential inputs configured to receive the AC square wave signal, a differential output with first and second differential outputs configured to produce the charging signal, and a plurality of switched capacitors that are selectively switched to achieve maximum power transfer efficiency for a selected coil combination used to transmit the power transfer signal, wherein the plurality of switched capacitors are coupled in parallel across the first and second differential inputs, wherein a first number of the plurality of switched capacitors are switched into the matching circuit when a first number of primary coils are included in the selected coil combination, and one or more additional switched capacitors are switched into the matching circuit when a second and larger number of primary coils are included in the selected coil combination. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A power transmitter for wirelessly charging an electronic device, the power transmitter comprising:
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an input configured to receive a variable DC input voltage that can vary in a range from about 5 to about 20 volts; an input voltage detector coupled to the input and configured to determine a determined magnitude of the DC input voltage; a full-bridge inverter with first and second transistor pairs, wherein the inverter is configured to generate an AC square-wave signal from the variable DC input voltage; a plurality of selectable primary coils configured to receive a charging signal and to selectively transmit a power transfer signal to a receiver coil of the electronic device; and a matching network coupled to the inverter and to the plurality of selectable primary coils, the matching network configured to generate the charging signal from the AC square-wave signal and to provide the charging signal to the plurality of selectable primary coils, the matching network including a plurality of switched capacitors coupled in parallel across first and second differential inputs; and a microcontroller coupled to the input voltage detector, the inverter, the matching network, and the plurality of selectable primary coils, and the matching network, the microcontroller configured to; control the inverter to generate the AC square-wave signal having a duty cycle selected to provide a predetermined equivalent voltage, wherein the inverter is configured to generate the AC square-wave signal with a relatively high duty cycle when a determined magnitude of the variable DC input voltage is relatively low, and the inverter is configured to generate the AC square-wave signal with a relatively low duty cycle when the determined magnitude of the variable DC input voltage is relatively high, control the plurality of selectable primary coils to selectively activate a selected coil combination that most effectively couples with the receiver coil of the electronic device, where the selected coil combination can include one or more of the plurality of selectable primary coils to facilitate transmission with different numbers of the selectable primary coils, and selectively couple the plurality of switched capacitors in the matching network to achieve maximum power transfer efficiency for the selected coil combination used to transmit the power transfer signal, wherein a first number of the plurality of switched capacitors are coupled into the matching circuit when a first number of primary coils are included in the selected coil combination, and one or more additional switched capacitors are coupled into the matching circuit when a second and larger number of primary coils are included in the selected coil combination.
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15. A method of wirelessly charging an electronic device, the method comprising:
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receiving, through an input, a variable DC input voltage; generating, by an inverter coupled to the input, an AC square-wave signal from the variable DC input voltage, wherein the AC square-wave signal is generated to have a duty cycle that provides a predetermined equivalent voltage, wherein the AC square-wave signal is generated with a relatively high duty cycle when a determined magnitude of the variable DC input voltage is relatively low, and the AC square-wave signal is generated with a relatively low duty cycle when the determined magnitude of the variable DC input voltage is relatively high; selectively switching a plurality of switched capacitors in a matching network to achieve maximum power transfer efficiency to a receiver coil in the electronic device, wherein the matching network is coupled between the inverter and a plurality of primary coils, wherein the plurality of switched capacitors is coupled in parallel across first and second differential inputs; generating a charging signal from the AC square-wave signal by the matching network; selecting, from the plurality of primary coils, a coil combination from multiple different coil combinations to determine the selected coil combination, each of the multiple different coil combinations including a number of the plurality of primary coils with at least one of the multiple different coil combinations including more than one of the plurality of primary coils to facilitate transmission with different numbers of primary coils; and driving the selected coil combination using the charging signal to transmit a power transfer signal to the receiver coil of the electronic device. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification