Wireless inductive power transfer

• US 9,866,073 B2
• Filed: 06/15/2015
• Issued: 01/09/2018
• Est. Priority Date: 06/19/2014
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Joye, Neil Francis, Van Wageningen, Andries, Abernethy, Simon George, Lulofs, Klaas Jacob
• Primary Examiner(s): Jackson, Stephen W
• Assistant Examiner(s): Sun, Pinping
• Application Number:
  US15/306,575
• Publication Number:
  US 20170093222A1
• Time in Patent Office: 939 Days
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H04B 5/24 Inductive coupling
• CPC Class Codes: H04B 5/263 Multiple coils at either side
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A wireless power transfer system includes a power transmitter (201) arranged to provide a power transfer to a power receiver (205) via a power transfer signal. The power receiver (205) comprises a first mode controller (709) for transmitting a standby mode exit request to the power transmitter (201) by changing a loading of a communication inductor (209) of the power transmitter (201). The power transmitter (201) comprises a mode controller (405) which controls the power transmitter (201) to operate in a standby mode wherein a presence of the power receiver (205) is detected but no power transfer signal is generated. It furthermore comprises a detector (403) for detecting an impedance change of the communication inductor (209). The mode controller (405) is arranged to initiate a transition from the standby mode to a power transfer mode in response to the detector (403) detecting the impedance change.

Claims

1. A wireless power transfer system including a power transmitter arranged to provide a power transfer to a power receiver via a wireless inductive power transfer signal generated by the power transmitter,

wherein:

the power receiver comprises a first mode controller for transmitting a standby mode exit request to the power transmitter by changing a loading of a communication inductor of the power transmitter; and

the power transmitter comprises;

the communication inductor for communicating with the power receiver;

a second mode controller for controlling the power transmitter to operate in a standby mode wherein a presence of the power receiver is detected but no power transfer signal is generated;

a detector for detecting an impedance change of the communication inductor;

and the second mode controller is arranged to initiate a transition from the standby mode to a power transfer mode in response to the detector detecting the impedance change;

wherein the communication inductor is part of a resonance circuit and the detector is arranged to apply an excitation signal comprising at least one excitation causing oscillations to the resonance circuit exceeding a duration of the excitation of the excitation signal, and to detect the impedance change from a measurement of at least one of a communication inductor voltage and a communication inductor current, wherein the measurement is performed with a time offset relative to a time of the excitation.

2. The wireless power transfer system of claim 1 wherein the power receiver is arranged to transmit the standby mode exit request in response to receiving a power-on user input.

3. The wireless power transfer system of claim 1 wherein the communication inductor is separate from a transmitter power coil generating the power transfer signal.

4. The wireless power transfer system of claim 1 wherein the power receiver is arranged to generate the standby mode exit request to comprise control data, and the power transmitter comprises a receiver for retrieving the control data and the second mode controller is arranged to adapt the transition from the standby mode to the power transfer mode based on the control data.

5. The power transmitter of claim 1 wherein the time offset is no less than 10 and no more than 60 time periods for a resonance of the resonance circuit.

6. A power transmitter for a wireless power transfer system including a power receiver arranged to receive power from the power transmitter via a wireless inductive power transfer signal generated by the power transmitter, and to transmit a standby mode exit request by changing a loading of a communication inductor;

the power transmitter comprising;

the communication inductor for communicating with the power receiver;

a mode controller for controlling the power transmitter to operate in a standby mode wherein a presence of the power receiver is detected but no power transfer signal is generated;

a detector for detecting an impedance change of the communication inductor;

and wherein the mode controller is arranged to initiate a transition from the standby mode to a power transfer mode in response to the detector detecting the impedance change;

wherein the communication inductor is part of a resonance circuit and the detector is arranged to apply an excitation signal comprising at least one excitation causing oscillations to the resonance circuit exceeding a duration of the excitation of the excitation signal, and to detect the impedance change from a measurement of at least one of a communication inductor voltage and a communication inductor current, wherein the measurement is performed with a time offset relative to a time of the excitation.

7. The power transmitter of claim 6 wherein the communication inductor is part of a resonance circuit having a resonance frequency;

and the detector is arranged to detect the impedance change based on an estimate of the resonance frequency, the detector further being arranged to determine the estimate of the resonance frequency in the stand-by phase.

8. The power transmitter of claim 6 wherein the excitation signal comprises repeated excitations having a time offset resulting in interference between oscillations of the resonance circuit for two consecutive excitations.

9. The power transmitter of claim 8 the detector is arranged to adapt a repetition interval for the repeated excitations based on an amplitude of at least one of a communication inductor voltage and a communication inductor current.

10. The power transmitter of claim 9 wherein the detector is arranged to adapt the repetition interval to maximize the at least one of the communication inductor voltage and the communication inductor current.

11. The power transmitter of claim 8 wherein an exponential time constant for the resonance circuit is no less than twice a duration of an excitation.

12. The power transmitter of claim 6 wherein the communication inductor is part of a resonance circuit and the detector is arranged to apply an excitation signal to the resonance circuit, and to adjust a repetition frequency for excitations of the excitation signal in response to a resonance frequency estimate for a resonance frequency of the resonance circuit when in the standby mode.

13. A method of operation for a wireless power transfer system including a power transmitter arranged to provide a power transfer to a power receiver via a wireless inductive power transfer signal generated by the power transmitter,

the method comprising:

the power transmitter operating in a standby mode wherein a presence of the power receiver is detected but no power transfer signal is generated;

the power receiver transmitting a standby mode exit request to the power transmitter by changing a loading of a communication inductor of the power transmitter;

the power transmitter detecting an impedance change of the communication inductor; and

the power transmitter initiating a transition from the standby mode to a power transfer mode in response to the detection of the impedance change;

wherein the communication inductor is part of a resonance circuit, the method further comprises the power transmitter applying an excitation signal comprising at least one excitation causing oscillations to the resonance circuit exceeding a duration of the excitation of the excitation signal, and the detection of the impedance change is from a measurement of at least one of a communication inductor voltage and a communication inductor current, wherein the measurement is performed with a time offset relative to a time of the excitation.

14. A method of operation for a power transmitter for a wireless power transfer system including a power receiver arranged to receive power from the power transmitter via a wireless inductive power transfer signal generated by the power transmitter, and to transmit a standby mode exit request by changing a loading of a communication inductor;

the method comprising;

controlling the power transmitter to operate in a standby mode wherein a presence of the power receiver is detected but no power transfer signal is generated;

detecting an impedance change of the communication inductor; and

initiating a transition from the standby mode to a power transfer mode in response to the detection of the impedance change;

wherein the communication inductor is part of a resonance circuit, the method further comprises the power transmitter applying an excitation signal comprising at least one excitation causing oscillations to the resonance circuit exceeding a duration of the excitation of the excitation signal, and the detection of the impedance change is from a measurement of at least one of a communication inductor voltage and a communication inductor current, wherein the measurement is performed with a time offset relative to a time of the excitation.