Wireless inductive power transfer
First Claim
1. A power transmitter for providing a power transfer to a power receiver using a wireless inductive power transfer signal, the power transmitter comprising:
- a transmitter inductor for generating an inductive carrier signal for load modulation in response to a voltage drive signal applied to at least one of the transmitter inductor and a resonance circuit comprising the transmitter inductor;
a measurement unit arranged to, for cycles of a reference signal synchronized to the voltage drive signal, perform first measurements of at least one of an inductor current and an inductor voltage for the transmitter inductor, each first measurement being over a measurement time interval being a subset of a cycle period of the reference signal and having a first time offset relative to the reference signal;
an adaptor for varying the first time offset and detecting an optimum measurement timing offset for the varying first time offset, the optimum measurement timing offset being detected as a time offset for the varying first time offset which results in a maximum demodulation depth for a demodulation depth reflecting a difference measure for first measurements generated by the measurement unit with the first time offset for different modulation loads of the inductive carrier signal; and
a demodulator for demodulating load modulation of the inductive carrier signal from first measurements with the first time offset set to the optimum measurement timing offset.
1 Assignment
0 Petitions
Accused Products
Abstract
A power transmitter (101) provides power transfer to a power receiver (105) using a wireless inductive power transfer signal. The power transmitter (101) comprises an inductor (103) generating the power transfer signal when a voltage drive signal is applied. A measurement unit (311) performs measurements of a current or voltage of the inductor (103). The measurements are performed with a time offset relative to a reference signal synchronized to the voltage drive signal. An adaptor (313) can vary the time offset to determine an optimum measurement timing offset resulting in a maximum demodulation depth which reflects a difference measure for measurements for different modulation loads of the power transfer signal. A demodulator (309) then demodulates load modulation of the inductive carrier signal from measurements with the time offset set to the optimum measurement timing offset. In some scenarios, both the timing and duration of measurements may be varied. The approach improves communication reliability.
4 Citations
14 Claims
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1. A power transmitter for providing a power transfer to a power receiver using a wireless inductive power transfer signal, the power transmitter comprising:
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a transmitter inductor for generating an inductive carrier signal for load modulation in response to a voltage drive signal applied to at least one of the transmitter inductor and a resonance circuit comprising the transmitter inductor; a measurement unit arranged to, for cycles of a reference signal synchronized to the voltage drive signal, perform first measurements of at least one of an inductor current and an inductor voltage for the transmitter inductor, each first measurement being over a measurement time interval being a subset of a cycle period of the reference signal and having a first time offset relative to the reference signal; an adaptor for varying the first time offset and detecting an optimum measurement timing offset for the varying first time offset, the optimum measurement timing offset being detected as a time offset for the varying first time offset which results in a maximum demodulation depth for a demodulation depth reflecting a difference measure for first measurements generated by the measurement unit with the first time offset for different modulation loads of the inductive carrier signal; and a demodulator for demodulating load modulation of the inductive carrier signal from first measurements with the first time offset set to the optimum measurement timing offset. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of operation for a power transmitter arranged to provide a power transfer to a power receiver using a wireless inductive power transfer signal, the method comprising:
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a transmitter inductor generating an inductive carrier signal for load modulation in response to a voltage drive signal applied to at least one of the transmitter inductor and a resonance circuit comprising the transmitter inductor; for cycles of a reference signal synchronized to the voltage drive signal, performing first measurements of at least one of an inductor current and an inductor voltage for the transmitter inductor, each first measurement being over a measurement time interval being a subset of a cycle period of the reference signal and having a first time offset relative to the reference signal; varying the first time offset and detecting an optimum measurement timing offset as a time offset for the varying first time offset which results in a maximum demodulation depth for a demodulation depth reflecting a difference measure for first measurements generated with the first time offset for different modulation loads of the inductive carrier signal; and demodulating load modulation of the inductive carrier signal from first measurements with the first time offset set to the optimum measurement timing offset.
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Specification