Wireless power transfer receiver having closed loop voltage control

• US 9,985,442 B2
• Filed: 09/24/2015
• Issued: 05/29/2018
• Est. Priority Date: 09/24/2015
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Von Novak, III, William Henry, Carobolante, Francesco, Irish, Linda Stacey, Wheatley, Charles Edward, Menegoli, Paolo
• Primary Examiner(s): Shin, Jeffrey
• Application Number:
  US14/863,538
• Publication Number:
  US 20170093167A1
• Time in Patent Office: 978 Days
• CPC Class Codes: H02J 50/12 of the resonant type
• 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 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge

Abstract

An apparatus for wirelessly receiving power via a wireless field generated by a transmitter includes a resonator configured to generate electrical current to power or charge a load based on a voltage induced in the resonator in response to the wireless field, a first variable capacitor electrically coupled to the resonator and configured to adjust a first capacitance of the first variable capacitor responsive to a first control signal, a second variable capacitor electrically coupled to the resonator and configured to adjust a second capacitance of the second variable capacitor responsive to a second control signal, and a control circuit configured to adjust and apply the first control signal and the second control signal to the first variable capacitor and the second variable capacitor, respectively, to adjust a resonant frequency of the resonator and a voltage output to the load based on an electrical characteristic indicative of a level of power output to the load.

Claims

1. An apparatus for wirelessly receiving power via a wireless field generated by a transmitter, the apparatus comprising:

a resonator configured to generate electrical current to power or charge a load based on a voltage induced in the resonator in response to the wireless field;

a first variable capacitor electrically coupled to the resonator and configured to adjust a first capacitance of the first variable capacitor responsive to a first control signal;

a second variable capacitor electrically coupled to the resonator and configured to adjust a second capacitance of the second variable capacitor responsive to a second control signal; and

a control circuit configured to adjust and apply the first control signal and the second control signal to the first variable capacitor and the second variable capacitor, respectively, to adjust a resonant frequency of the resonator and a voltage output to the load based on an electrical characteristic indicative of a level of power output to the load, wherein the control circuit is configured to control the resonant frequency of the resonator by adjusting the first variable capacitor responsive to the voltage output of the load, a reference voltage and a phase difference of a signal across the resonator.

2. The apparatus of claim 1, wherein the control circuit comprises a closed loop feedback circuit configured to adjust the first variable capacitor and the second variable capacitor responsive to a reference signal, the reference signal comprising the reference voltage.

3. The apparatus of claim 1, wherein the second variable capacitor is configured to adjust the voltage output of the load.

4. The apparatus of claim 1, wherein the first variable capacitor and the second variable capacitor are each configured to provide a portion of a total capacitance, the total capacitance configured to simultaneously adjust the resonant frequency of the resonator and a voltage output of the load.

5. The apparatus of claim 4, wherein the portion of the total capacitance provided by the first variable capacitor and the second variable capacitor causes the resonator to remain at the resonant frequency as the load varies, and causes an impedance of the resonator to be maintained as real.

6. The apparatus of claim 1, wherein the control circuit is configured to control the voltage output by adjusting the second variable capacitor responsive to the voltage output of the load and the reference voltage.

7. The apparatus of claim 1, wherein the control circuit is configured to control the voltage output by adjusting the second variable capacitor responsive to the voltage output of the load and the reference voltage.

8. The apparatus of claim 4, wherein the control circuit is configured to control the resonant frequency of the resonator and the voltage output of a wireless power receiver responsive to the voltage output of the load and the reference voltage.

9. The apparatus of claim 8, wherein the portion of the total capacitance provided by the first variable capacitor is inversely proportional to the portion of the total capacitance provided by the second variable capacitor.

10. The apparatus of claim 1, wherein:

in response to an increasing voltage output, the second variable capacitor is adjusted to reduce the voltage output; and

the first variable capacitor is adjusted to reduce the electrical current in the resonator.

11. The apparatus of claim 1, wherein:

in response to a decreasing voltage output, the second variable capacitor is adjusted to increase the voltage output; and

the first variable capacitor is adjusted to increase the electrical current in the resonator.

12. A method for wirelessly receiving power via a wireless field generated by a transmitter, the method comprising:

generating an electrical current to power or charge a load based on a voltage induced in a resonator in response to the wireless field;

adjusting a first variable capacitance responsive to a first control signal;

adjusting a second variable capacitance responsive to a second control signal;

applying the first control signal and the second control signal to the first variable capacitance and the second variable capacitance, respectively, to control a resonant frequency of the resonator and a voltage output to the load based on an electrical characteristic indicative of a level of power output to the load by adjusting the first variable capacitance responsive to the voltage output to the load, a reference voltage and a phase difference of a signal across the resonator.

13. The method of claim 12, further comprising applying the first control signal and the second control signal responsive to a reference signal, the reference signal comprising the reference voltage.

14. The method of claim 12, further comprising adjusting the second variable capacitance to adjust the voltage output to the load.

15. The method of claim 12, further comprising adjusting the first variable capacitance and the second variable capacitance to provide a portion of a total capacitance, to simultaneously adjust the resonant frequency of the resonator and the voltage output to the load.

16. The method of claim 15, wherein the portion of the total capacitance provided by the first variable capacitance and the second variable capacitance causes the resonator to remain at the resonant frequency as the load varies, and causes an impedance of the resonator to be maintained as real.

17. The method of claim 14, further comprising controlling the voltage output to the load by adjusting the second variable capacitance responsive to the voltage output to the load and the reference voltage.

18. The method of claim 12, further comprising controlling the voltage output to the load by adjusting the second variable capacitance responsive to the voltage output to the load and the reference voltage.

19. The method of claim 15, further comprising controlling the resonant frequency of the resonator and the voltage output to the load responsive to the voltage output to the load and the reference voltage.

20. The method of claim 15, wherein the portion of the total capacitance provided by the first variable capacitance is inversely proportional to the portion of the total capacitance provided by the second variable capacitance.

21. The method of claim 12, further comprising:

adjusting the second variable capacitance to reduce the voltage output to the load in response to an increasing voltage output to the load; and

adjusting the first variable capacitance to reduce the electrical current in the resonator.

22. The method of claim 12, further comprising:

adjusting the second variable capacitance to increase the voltage output to the load in response to a decreasing voltage output to the load; and

adjusting the first variable capacitance to increase the electrical current in the resonator.

23. A device for wirelessly receiving power via a wireless field generated by a transmitter, comprising:

means for generating an electrical current to power or charge a load in response to the wireless field;

means for adjusting a first capacitance responsive to a first control signal;

means for adjusting a second capacitance responsive to a second control signal; and

means for applying the first control signal and the second control signal to the means for adjusting the first capacitance and the means for adjusting the second capacitance, respectively, to control a resonant frequency of the means for generating the electrical current and a voltage output to the load based on an electrical characteristic indicative of a level of power output to the load by adjusting the first variable capacitance responsive to the voltage output to the load, a reference voltage and a phase difference of a signal across the means for generating the electric current.

24. The device of claim 23, further comprising means for applying the first control signal and the second control signal responsive to a reference signal, the reference signal comprising the reference voltage.

25. An apparatus for wirelessly receiving power via a wireless field generated by a transmitter, the apparatus comprising:

a resonator configured to generate electrical current to power or charge a load based on a voltage induced in the resonator in response to the wireless field;

a first variable capacitor electrically coupled to the resonator and configured to adjust a first capacitance of the first variable capacitor responsive to a first control signal;

a second variable capacitor electrically coupled to the resonator and configured to adjust a second capacitance of the second variable capacitor responsive to a second control signal; and

a closed loop feedback circuit configured to adjust and apply the first control signal and the second control signal to the first variable capacitor and the second variable capacitor, respectively, to adjust a resonant frequency of the resonator and a voltage output to the load based on an electrical characteristic indicative of a level of power output to the load, a reference signal, and a phase difference of a signal across the resonator.

26. The apparatus of claim 25, wherein:

in response to an increasing voltage output, the second variable capacitor is adjusted to reduce the voltage output, and the first variable capacitor is adjusted to detune the resonator away from resonance; and

in response to a decreasing voltage output, the second variable capacitor is adjusted to increase the voltage output, and the first variable capacitor is adjusted tune the resonator closer to resonance.