Wireless power transmission unit and power generator with the wireless power transmission unit

• US 8,698,350 B2
• Filed: 10/06/2011
• Issued: 04/15/2014
• Est. Priority Date: 10/08/2010
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Kanno, Hiroshi
• Primary Examiner(s): Deberadinis, Robert L.
• Application Number:
  US13/267,033
• Publication Number:
  US 20120086281A1
• Time in Patent Office: 922 Days
• Field of Search: 307/18, 307/19
• US Class Current: 307/19
• CPC Class Codes: H01Q 1/248 provided with an AC/DC converting device, e.g. rectennas
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 7/35 with light sensitive cells

Abstract

A wireless power transmission unit includes oscillators that convert DC energy into RF energy with a frequency f0, power transmitting antennas, and power receiving antennas. Each power transmitting antenna is a series resonant circuit in which a power transmitting inductor and a first capacitor are connected in series. Each power receiving antenna is a parallel resonant circuit in which a power receiving inductor and a second capacitor are connected in parallel. If the oscillator has a voltage step-up ratio Voc, the power transmitting inductor has an inductance L1, the power receiving inductor has an inductance L2, and the power transmitting and power receiving antennas and have a coupling coefficient k, (L2/L1)≧4(k/Voc)² is satisfied. The absolute value of the phase difference θres between the respective resonant magnetic fields of first and second pairs of resonant antennas is set to fall within the range of 90 to 180 degrees.

Claims

1. A wireless power transmission unit comprising:

first and second wireless power transmitting sections, each of the first and second wireless power transmitting sections including

an oscillator that converts DC energy into RE energy having a frequency f0,

a power transmitting antenna that transmits the RF energy and includes a first inductor and a first capacitor connected together in series to form a series resonant circuit with a resonant frequency fT, and

a power receiving antenna that receives at least a part of the RF energy transmitted by the power transmitting antenna by coupling a resonant magnetic field and includes a second inductor and a second capacitor connected in parallel with each other to form a parallel resonant circuit with a resonant frequency fR,

wherein the resonant frequencies fT and fR are set to be substantially equal to the frequency f0 of the RF energy, and

wherein if the oscillator has a voltage step-up ratio Voc, the first inductor has an inductance L1, the second inductor has an inductance L2, and the power transmitting and power receiving antennas have a coupling coefficient k,

the first and second wireless power transmitting sections satisfy (L2/L1)≧

4(k/Voc)²;

a combining section that combines together RF energies supplied from the respective power receiving antennas of the first and second wireless power transmitting sections and outputs the combined RE energy; and

a control section that controls the respective oscillators of the first and second wireless power transmitting sections such that the respective phases of the resonant magnetic fields of the first and second wireless power transmitting sections have a phase difference θ

res of 90 to 180 degrees therebetween.

2. The wireless power transmission unit of claim 1, wherein the phase difference θ

res is set to be 180 degrees.

3. The wireless power transmission unit of claim 1, wherein the control section controls the respective phases θ

ta and θ

tb of RF energies that have been transmitted from the respective oscillators of the first and second wireless power transmitting sections, thereby setting the absolute value of the phase difference θ

t between the phases θ

ta and θ

tb to be 90 to 180 degrees therebetween.

4. The wireless power transmission unit of claim 3, wherein the absolute value of the phase difference θ

t is set to be 180 degrees.

6. The power generator of claim 3, wherein the power generating section is a solar power generating section.

7. The power generator of claim 3, wherein the solar power generating section uses crystalline silicon.

5. A power generator comprising:

first and second power generating units, each of the first and second power generating units including

a power generating section that outputs DC energy,

an oscillator that converts the DC energy supplied from the power generating section into RF energy having a frequency f0,

a power transmitting antenna that transmits the RF energy and includes a first inductor and a first capacitor connected together in series to form a series resonant circuit with a resonant frequency fT, and

a power receiving antenna that receives at least a part of the RF energy transmitted by the power transmitting antenna by coupling a resonant magnetic field and includes a second inductor and a second capacitor connected in parallel with each other to form a parallel resonant circuit with a resonant frequency fR,

wherein the resonant frequencies fT and fR are set to be substantially equal to the frequency f0 of the RF energy, and

wherein if the oscillator has a voltage step-up ratio Voc, the first inductor has an inductance L1, the second inductor has an inductance L2, and the power transmitting and power receiving antennas have a coupling coefficient k, the first and second power generating units satisfy (L2/L1)≧

4(k/Voc)²;

a combining section that combines together RF energies supplied from the respective power receiving antennas of the first and second power generating units and outputs the combined RF energy; and

a control section that controls the respective oscillators of the first and second power generating units such that the respective phases of the resonant magnetic fields of the first and second power generating units have a phase difference θ

res of 90 to 180 degrees therebetween.

8. The power generator of claim 5, wherein when an output terminal of the power receiving antenna is connected to a load that follows the power receiving antenna, the output impedance Zoc of the oscillator is substantially equal to the input impedance Zin of the power transmitting antenna.

9. The power generator of claim 5, wherein when an output terminal of the oscillator is connected to an input terminal of the power transmitting antenna, the output impedance Zout of the power receiving antenna is substantially equal to the input impedance of a load that follows the power receiving antenna.

10. The power generator of claim 5, wherein (L2/L1)≧

100×

(k/Voc)² is satisfied.

11. The power generator of claim 5, wherein (L2/L1)≧

10000×

(k/Voc)² is satisfied.

12. The power generator of claim 5, wherein the power generating section and the power transmitting antenna are arranged outside of a building, and

wherein the power receiving antenna is installed inside of the building.

13. The power generator of claim 5, wherein the first and second inductors both have an air-core spiral structure.

14. The power generator of claim 5, wherein L1<

L2 is satisfied.

15. The power generator of claim 5, wherein the number N2 of turns of the second inductor is greater than the number N1 of turns of the first inductor.

16. The power generator of claim 5, wherein the second inductor is larger in area than the first inductor.

17. The power generator of claim 16, wherein when the first and second inductors are projected onto the power transmitting antenna'"'"'s arrangement plane, the first inductor is included within, and located close to the periphery of, the area defined by the projected profile of the second inductor.

18. The power generator of claim 16, wherein when the first and second inductors are projected onto the power transmitting antenna'"'"'s arrangement plane, the first inductor is located close to the periphery of the area defined by the projected profile of the second inductor.

19. The power generator of claim 5, wherein a phase control section that matches the phases of RF energies supplied from the respective power receiving antennas of the first and second power generating units is arranged between the power receiving antenna and the combining section in each of the first and second power generating units.

20. The power generator of claim 5, wherein the phase difference is 180 degrees, and

wherein in order to match the phases of RF energies supplied from the respective power receiving antennas of the first and second power generating units, the polarity of connection between the power receiving antenna and the combining section in the first power generating unit is inverse of the polarity of connection in the second power generating unit.

21. The power generator of claim 5, comprising a frequency converting circuit, which converts the RF energy supplied from the combining section into alternating current or direct current that has a lower frequency than the RF energy.

22. The power generator of claim 5, wherein each of the first and second power generating units comprises a frequency converting circuit, which converts the RF energy supplied from the power receiving antenna into alternating current or direct current that has a lower frequency than the RF energy.

23. The power generator of claim 5, wherein the combining section is connected to a utility grid.

24. A power generator comprising:

first and second power generating units, each of the first and second power generating units including

a power generating section that outputs DC energy,

an oscillator that converts the DC energy supplied from the power generating section into RF energy having a frequency f0,

a power transmitting antenna that transmits the RF energy and includes a first inductor and a first capacitor connected together in series to form a series resonant circuit with a resonant frequency fT,

a power receiving antenna that receives at least a part of the RE energy transmitted by the power transmitting antenna by coupling a resonant magnetic field and includes a second inductor and a second capacitor connected in parallel with each other to form a parallel resonant circuit with a resonant frequency fR, and

a rectifier that converts the RF energy supplied from the power receiving antenna into DC energy

wherein the resonant frequencies fT and fR are set to be substantially equal to the frequency f0 of the RF energy, and

wherein if the oscillator has a voltage step-up ratio Voc, the rectifier has a voltage step-up ratio Vrr, the first inductor has an inductance L1, the second inductor has an inductance L2, and the power transmitting and power receiving antennas have a coupling coefficient k, the first and second power generating units satisfy (L2/L1)≧

4(k/(Voc×

Vrr))²;

an output section that combines RF energies received from the respective power transmitting antennas of the first and second power generating units and outputs the combined RF energy; and

a control section that controls the respective oscillators of the first and second power generating units such that the respective phases of the resonant magnetic fields of the first and second power generating units have a phase difference θ

res of 90 to 180 degrees therebetween.

25. The power generator of claim 24, wherein the power generating section is a solar power generating section.

26. The power generator of claim 24, wherein when an output terminal of the rectifier is connected to a load that follows the rectifier, the output impedance Zoc of the oscillator is substantially equal to the input impedance Zin of the power transmitting antenna.

27. The power generator of claim 24, wherein when an output terminal of the oscillator is connected to an input terminal of the power transmitting antenna, the output impedance Zout of the rectifier is substantially equal to the input impedance of a load that follows the rectifier.

28. The power generator of claim 24, wherein (L2/L1)≧

100×

(k/(Voc×

Vrr))² is satisfied.

29. The power generator of claim 24, wherein (L2/L1)≧

2304×

(k/Voc)² is satisfied.

30. The power generator of claim 24, wherein (L2/L1)≧

10000×

(k/Voc)² is satisfied.

31. The power generator of claim 24, wherein the rectifier is a voltage doubler rectifier circuit with a voltage step-up ratio Vrr of at least two.

32. A power generator comprising

N power generating units, where N is an integer that is equal to or greater than four, and

a combining section that combines together the respective outputs of the power generating units in parallel with each other,

wherein each said power generating unit comprises:

a power generating section that outputs DC energy;

an oscillator that converts the DC energy supplied from the power generating section into RF energy having a frequency f0;

a power transmitting antenna that transmits the RF energy and includes a first inductor and a first capacitor connected together in series to form a series resonant circuit with a resonant frequency fT; and

a power receiving antenna that receives at least a part of the RF energy transmitted by the power transmitting antenna by coupling a resonant magnetic field and that includes a second inductor and a second capacitor connected in parallel with each other to form a parallel resonant circuit with a resonant frequency fR,

wherein the resonant frequencies fT and fR are set to be substantially equal to the frequency f0 of the RF energy, and

wherein if the oscillator has a voltage step-up ratio Voc, the first inductor has an inductance L1, the second inductor has an inductance L2, and the power transmitting and power receiving antennas have a coupling coefficient k, the power generating unit satisfies (L2/L1)≧

4(k/Voc)², and

wherein the power generator further includes a control section, which controls the respective oscillators of the power generating units such that the resonant magnetic field in one of two proximate ones of the N power generating units has a phase difference θ

res of 90 to 180 degrees from the resonant magnetic field in the other power generating unit.