Wireless inductive power transfer
First Claim
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.
1 Assignment
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Accused Products
Abstract
A wireless power transmitter (101)) comprises a resonance circuit (201) comprises a transmitter inductor (103) for generating a power transfer signal for wirelessly transferring power to the power receiver (105). A driver (203) generates a drive signal for the resonance circuit (201) and a resonance modification circuit (505) aligns the resonance frequency of the resonance circuit (201) with the drive frequency of the drive signal by slowing a state change for resonance circuit (201) for a fractional time interval of cycles of the drive signal. A load estimator (509) generates a load estimate reflecting an equivalent load resistor for the transmitter inductor (103) reflecting the loading of the power transfer signal. A drive frequency adapter (511) then adapts the drive frequency in response to the load estimate. The invention may in particular improve load modulation communication quality.
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Citations
20 Claims
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1. A power transmitter for inductively transferring power to a power receiver, the power transmitter comprising:
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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, and wherein the first equivalent parallel load resistance is lower than the second equivalent parallel load resistance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13)
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9. A power transmitter for inductively transferring power to a power receiver, the power transmitter comprising:
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a resonance circuit comprising a capacitive impedance and an inductive impedance, wherein the inductive impedance comprises a transmitter inductor, wherein the transmitter inductor provides a power transfer signal for wirelessly transferring power to the power receiver; a driver that provides 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 natural resonance frequency of the capacitive impedance and inductive impedance 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, wherein the first equivalent parallel load resistance is higher than the second equivalent parallel load resistance. - View Dependent Claims (16, 17, 18, 19, 20)
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14. A method of operation for a power transmitter inductively transferring power for to a power receiver, the power transmitter comprising a resonance circuit comprising a capacitive impedance and an inductive impedance, the inductive impedance comprising a transmitter inductor for generating a power transfer signal for wirelessly transferring power to the power receiver;
- the method comprising;
generating a drive signal for the resonance circuit, wherein the drive signal has a drive frequency; aligning 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, generating 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 adapting the drive frequency in response to the load estimate; wherein adapting the drive frequency comprises; adapting 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, and adapting 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, and wherein the first equivalent parallel load resistance is lower than the second equivalent parallel load resistance.
- the method comprising;
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15. A wireless power transfer system comprising power transmitter and a power receiver, the power transmitter comprising:
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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 wherein the driver 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 the 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 generates 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 adaptor 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, and wherein the first equivalent parallel load resistance is lower than the second equivalent parallel load resistance.
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Specification