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Wireless inductive power transfer

  • US 10,536,035 B2
  • Filed: 11/01/2016
  • Issued: 01/14/2020
  • Est. Priority Date: 11/02/2015
  • Status: Active Grant
First Claim
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1. A power transmitter for inductively transferring power to a power receiver, the power transmitter comprising:

  • a resonance circuit comprising a capacitive impedance and an inductive impedance,wherein the inductive impedance comprises a transmitter inductor,wherein the transmitter inductor generates a power transfer signal for wirelessly transferring power to the power receiver;

    a driver that generates a drive signal for the resonance circuit,wherein the drive signal has a drive frequency;

    a resonance modification circuit,wherein the resonance modification circuit aligns a resonance frequency of the resonance circuit with the drive frequency by slowing a state change for at least one of the capacitive impedance and the inductive impedance for a fractional time interval of each of at least a plurality of cycles of the drive signal;

    a load estimator,wherein the load estimator provides a load estimate,wherein the load estimate reflects an equivalent load resistor for the transmitter inductor,wherein the equivalent load resistor reflects a loading of the power transfer signal; and

    a drive frequency adapter,wherein the drive frequency adapter adapts the drive frequency in response to the load estimate;

    wherein the drive frequency adapter adapts the drive frequency to be a first distance away from a resonance frequency of a power receiving resonance circuit of the power receiver for a load estimate indicative of a first equivalent parallel load resistance,wherein the drive frequency adapter adapts the drive frequency to be a second distance away from a resonance frequency of a power receiving resonance circuit of the power receiver for a load estimate indicative of a second equivalent parallel load resistance,wherein the first distance is greater than the second distance, andwherein the first equivalent parallel load resistance is lower than the second equivalent parallel load resistance.

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