Wireless power transmitters with wide input voltage range and methods of their operation

摘要

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.

主权项

1. A power transmitter for wirelessly charging an electronic device, the power transmitter comprising:
an input configured to receive a DC input voltage; an inverter coupled to the input to receive the DC input voltage, the inverter configured to generate an AC square-wave signal having a duty cycle selected to provide a predetermined equivalent voltage; a matching network coupled to the inverter to receive the AC square-wave signal, the matching network configured to generate a charging signal from the AC square-wave signal, the matching network including a plurality of switched capacitors; a plurality of primary coils coupled to the matching network to receive the 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 wherein the plurality of switched capacitors are selectively switched based on the number of the plurality of primary coils in a selected coil combination used to transmit the power transfer signal such that the matching network resonates with the selected coil combination at a resonant frequency that closely matches a fundamental frequency of the charging signal.