Wireless power feeder, wireless power receiver, and wireless power transmission system

• US 8,829,725 B2
• Filed: 03/18/2011
• Issued: 09/09/2014
• Est. Priority Date: 03/19/2010
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Urano, Takashi
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): Mourad, Rasem
• Application Number:
  US13/051,184
• Publication Number:
  US 20110227420A1
• Time in Patent Office: 1,271 Days
• Field of Search: 307/104
• US Class Current: 307/104
• 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: H04B 5/26 using coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

Power is fed from a power feeding coil L2 to a power receiving coil L3 by magnetic resonance. A VCO 202 alternately turns ON/OFF switching transistors Q1 and Q2 at a drive frequency fo, whereby AC power is supplied to the power feeding coil L2, and then the AC power is supplied from the power feeding coil L2 to the power receiving coil L3. A phase detection circuit 114 detects a phase difference between current and voltage phases, and the VCO 202 adjusts the drive frequency fo such that the phase difference becomes zero. When load voltage is changed, the detected voltage phase value is adjusted with the result that the drive frequency fo is adjusted.

Claims

1. A wireless power feeder that wirelessly feeds power from a power feeding coil to a power receiving coil using a magnetic field resonance phenomenon between the power feeding coil and the power receiving coil, the feeder comprising:

the power feeding coil;

a power transmission control circuit that feeds AC power to the power feeding coil at a drive frequency so as to make the power feeding coil feed the AC power to the power receiving coil;

a phase detection circuit that detects a phase difference between voltage and current phases of the AC power;

a signal receiving coil that receives, from the AC power receiving side, an output signal having a duty ratio indicating an output level; and

a signal adjustment circuit that DC-converts the output signal in accordance with the duty ratio,

the power transmission control circuit adjusting the drive frequency so as to reduce the phase difference,

the phase detection circuit performing ex-post adjustment of the detected value of one or both of the voltage and current phases in accordance with a signal level of the DC-converted output signal.

2. The wireless power feeder according to claim 1, wherein the phase detection circuit compares a first phase value indicating a timing at which a voltage level of the AC power becomes a first reference value and a second phase value indicating a timing at which a current level of the AC power becomes a second reference value to detect the phase difference and changes one or both of the first and second reference values in accordance with the signal level to perform ex-post adjustment of one or both of the first and second phase values.

3. The wireless power feeder according to claim 1, wherein the signal receiving coil is a single-winding coil.

4. The wireless power feeder according to claim 1, wherein the coil plane of the signal receiving coil and that of the power feeding coil are substantially the same.

5. The wireless power feeder according to claim 1, wherein the signal adjustment circuit extracts an output signal component from the AC voltage detected in the signal receiving coil through a band-pass filter.

6. The wireless power feeder according to claim 1, wherein the power transmission control circuit causes the power feeding coil to which no capacitor is connected in series or in parallel, to feed the AC power to the power receiving coil.

7. The wireless power feeder according to claim 1, wherein the power feeding coil does not form, together with the circuit elements on the power feeding side, a resonance circuit having a resonance point corresponding to a resonance frequency of the power receiving coil.

8. The wireless power feeder according to claim 1, wherein no capacitor is inserted in series or in parallel to the power feeding coil.

9. A wireless power receiver that wirelessly receives, at a power receiving coil, AC power fed from the wireless power feeder as claimed in claim 1, comprising:

a receiving coil circuit that includes the power receiving coil and a capacitor;

a loading circuit that includes a loading coil that is magnetically coupled to the power receiving coil to receive the AC power from the power receiving coil and a load to which power is supplied from the loading coil;

a signal generation circuit that generates an output signal having a duty ratio indicating an output voltage applied to a part of the loading circuit; and

a signal transmitting coil that transmits the output signal to the wireless power feeder.

10. The wireless power receiver according to claim 9, wherein the signal generation circuit transmits the output signal as a signal indicating a difference value between the output voltage and a reference voltage by the duty ratio.

11. The wireless power receiver according to claim 9, wherein

the signal generation circuit includes:

a control signal generation circuit that generates a control signal at a control frequency; and

a comparison circuit that generates an enable signal when a predetermined magnitude relationship is established between the signal level of the control signal and the output voltage, and

the duty ratio of the output signal is determined based on the duty ratio of the enable signal.

12. The wireless power receiver according to claim 11, wherein

the signal generation circuit further includes a reference signal generation circuit that generates a reference signal having a reference frequency higher than the control frequency, and

the signal generation circuit transmits the reference signal as the output signal while the enable signal is being generated.

13. The wireless power receiver according to claim 9, wherein the signal transmitting coil is a single-winding coil.

14. The wireless power receiver according to claim 9, wherein the coil plane of the signal transmitting coil and that of the power receiving coil are substantially the same.

15. A wireless power transmission system for wirelessly feeding power from a power feeding coil to a power receiving coil using a magnetic field resonance phenomenon between the power feeding coil and the power receiving coil, the system comprising:

a power transmission control circuit that supplies AC power to the power feeding coil at a drive frequency;

a loading circuit that includes a loading coil that is magnetically coupled to the power receiving coil to receive the AC power from the power receiving coil and a load that receives power from the loading coil;

a signal generation circuit that generates an output signal having a duty ratio indicating an output voltage applied to a part of the loading circuit;

a signal transmitting coil that transmits the generated output signal to the power feeding side;

a signal receiving coil that receives the transmitted output signal;

a signal adjustment circuit that DC-converts the received output signal in accordance with the duty ratio; and

a phase detection circuit that detects a phase difference between voltage and current phases of the AC power,

the power transmission control circuit adjusting the drive frequency so as to reduce the phase difference, and

the phase detection circuit performing ex-post adjustment of the detected value of one or both of the voltage and current phases in accordance with a signal level of the DC-converted output signal.

16. A wireless power feeder that wirelessly feeds power from a power feeding coil to a power receiving coil using a magnetic field resonance phenomenon between the power feeding coil and the power receiving coil, the feeder comprising:

the power feeding coil;

a power transmission control circuit that feeds AC power to the power feeding coil at a drive frequency so as to make the power feeding coil feed the AC power to the power receiving coil;

a phase detection circuit that detects a phase difference between voltage and current phases of the AC power;

a signal receiving coil that receives, from the AC power receiving side, an output signal indicating an output level by the magnitude of a signal frequency; and

a signal adjustment circuit that DC-converts the output signal in accordance with the signal frequency,

the power transmission control circuit adjusting the drive frequency so as to reduce the phase difference, and

the phase detection circuit performing ex-post adjustment of the detected value of one or both of the voltage and current phases in accordance with a signal level of the DC-converted output signal.

17. The wireless power feeder according to claim 16, wherein the phase detection circuit compares a first phase value indicating a timing at which the voltage level of the AC power becomes a first reference value and a second phase value indicating a timing at which the current level of the AC power becomes a second reference value to detect the phase difference and changes one or both of the first and second reference values based on the output signal to perform ex-post adjustment of one or both of the first and second phase values.

18. The wireless power feeder according to claim 16, wherein the signal receiving coil is a single-winding coil.

19. The wireless power feeder according to claim 16, wherein the coil plane of the signal receiving coil and that of the power feeding coil are substantially the same.

20. The wireless power feeder according to claim 16, wherein the signal adjustment circuit extracts an output signal component from the AC voltage detected in the signal receiving coil through a band-pass filter.

21. The wireless power feeder according to claim 16, wherein the power transmission control circuit causes the power feeding coil to which no capacitor is connected in series or in parallel, to feed the AC power to the receiving coil.

22. The wireless power feeder according to claim 16, wherein the power feeding coil does not form, together with circuit elements on the power feeding side, a resonance circuit having a resonance point corresponding to the resonance frequency of the power receiving coil.

23. The wireless power feeder according to claim 16, wherein no capacitor is inserted in series or in parallel to the power feeding coil.

24. A wireless power receiver that receives, at a power receiving coil, AC power fed from the wireless power feeder as claimed in claim 16 by wireless, said receiver comprising:

a receiving coil circuit that includes the power receiving coil and a capacitor;

a loading circuit that includes a loading coil that is magnetically coupled to the power receiving coil to receive the AC power from the power receiving coil and a load to which power is supplied from the loading coil;

a signal generation circuit that generates an output signal indicating an output voltage applied to a part of the loading circuit by a signal frequency; and

a signal transmitting coil that transmits the output signal to the wireless power feeder.

25. The wireless power receiver according to claim 24, wherein the signal generation circuit generates the output signal as a signal indicating a difference value between the output voltage and a reference voltage by the signal frequency.

26. The wireless power receiver according to claim 24, wherein the signal transmitting coil is a single-winding coil.

27. The wireless power receiver according to claim 24, wherein the coil plane of the signal transmitting coil and that of the power receiving coil are substantially the same.

28. A wireless power transmission system for wirelessly feeding power from a power feeding coil to a power receiving coil using a magnetic field resonance phenomenon between the power feeding coil and the power receiving coil, the system comprising:

a power transmission control circuit that supplies AC power to the power feeding coil at a drive frequency;

a loading circuit that includes a loading coil that is magnetically coupled to the power receiving coil to receive the AC power from the power receiving coil and a load circuit that receives power from the loading coil;

a signal generation circuit that generates an output signal indicating an output voltage applied to a part of the loading circuit by a signal frequency;

a signal transmitting coil that transmits the generated output signal to the power feeding side;

a signal receiving coil that receives the transmitted output signal;

a signal adjustment circuit that DC-converts the received output signal in accordance with the signal frequency; and

a phase detection circuit that detects a phase difference between voltage and current phases of the AC power,

the power transmission control circuit adjusting the drive frequency so as to reduce the phase difference, and

the phase detection circuit performing ex-post adjustment of the detected value of one or both of the voltage and current phases in accordance with a signal level of the DC-converted output signal.