Wireless power transfer load modulation enhancement
AssigneeAvago Technologies International Sales Pte. Limited
InventorsJohn Stuart Walley, Ryan Michael Desrosiers, Vadim Bishtein
Life of this patent
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Abstract
A wireless power transfer (WPT) receiver circuit includes a receive coil to couple to a transmit coil of a WPT transmitter circuit. A rectifier is coupled to the receive coil to generate a rectified voltage. The rectifier comprises a bridge rectifier circuit including a first set of switching elements. A load modulation circuit facilitates communication between the WPT receiver circuit and the WPT transmitter circuit. The load modulation circuit includes a single modulation capacitor and one or more modulation switching elements. At least one node of one of the modulation switching elements is connected to an input node of the rectifier.
Claims20
A wireless power transfer (WPT) receiver circuit comprising:
- a receive coil configured to couple to a transmit coil of a WPT transmitter circuit;
- a rectifier coupled to the receive coil and configured to generate a rectified voltage, wherein the rectifier comprises a bridge rectifier circuit including a first set of switching elements;
- and
- a load modulation circuit configured to facilitate communication between the WPT receiver circuit and the WPT transmitter circuit, the load modulation circuit comprising a single modulation capacitor and one or more modulation switching elements, wherein at least one node of one of the one or more modulation switching elements is connected to an input node of the rectifier, wherein the one or more modulation switching elements comprises two field-effect transistor (FET) switches, wherein the single modulation capacitor is connected between first nodes of two FET switches, and wherein the WPT transmitter circuit further comprises at least one variable resistor connected in series or in parallel with the single modulation capacitor.
A wireless power transfer (WPT) receiver circuit comprising:
- a receive coil configured to couple to a transmit coil of a WPT transmitter circuit;
- a rectifier coupled to the receive coil and configured to generate a rectified voltage, wherein the rectifier comprises a bridge rectifier circuit including a first and a second pair of switching devices, and wherein each switching device of the first pair of switching devices includes at least two parallel-connected switching elements;
- and
- a load modulation circuit configured to facilitate communication between the WPT receiver circuit and the WPT transmitter circuit, the load modulation circuit comprising modulation switch elements wherein the modulation switch elements comprise FET switches coupled in series to adjustable resistors and to a single modulation capacitor.
A method for enhancing load modulation in a wireless power transfer (WPT) receiver, the method comprising:
- providing a damping load;
- coupling the damping load to an output node of a rectifier circuit of the WPT receiver using a damping switch;
- reducing oscillations associated with a load modulation circuit of the WPT receiver by closing the damping switch to apply the damping load in a time window including a modulation event;
- and
- coupling an adjustable resistor in series with a first set of FET switches of the rectifier circuit, when a second set of FET switches of the rectifier circuit are conducting current,
- wherein:
- the load modulation circuit comprises modulation FET switches controlled by a modulation pulse, and
- the modulation event includes application of the modulation pulse to a gate terminal of a modulation FET switch.
Dependencies are inferred from the claim text.