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

• US 8,508,076 B2
• Filed: 08/10/2010
• Issued: 08/13/2013
• Est. Priority Date: 08/13/2009
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Kanno, Hiroshi
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): VU, TOAN T
• Application Number:
  US12/853,351
• Publication Number:
  US 20110037322A1
• Time in Patent Office: 1,099 Days
• Field of Search: 307/104
• US Class Current: 307/104
• CPC Class Codes: H02J 50/005 Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves

Abstract

A wireless power transmission unit includes an oscillator for converting DC energy into RF energy having a frequency f0 and a first antenna for transmitting the RF energy. The first antenna includes a first inductor and a first capacitor that are connected together in series to form a series resonant circuit with a resonant frequency fT. The unit further includes a second antenna for receiving, by resonant magnetic coupling, at least a part of the RF energy that has been transmitted by the first antenna. The second antenna includes a second inductor and a second capacitor that are connected in parallel with each other to form a parallel resonant circuit with a resonant frequency fR. The resonant frequencies fT and fR are set to be substantially equal to the frequency f0 of the RF energy, the oscillator has a voltage step-up ratio Voc, the first inductor has an inductance L1, the second inductor has an inductance L2, the second inductor is coupled with the first inductor by a resonant magnetic field at a coupling coefficient k which is set to be less than 0.5, and the power transmission unit satisfies (L2/L1)≧4(k/Voc)².

Claims

1. A wireless power transmission unit comprising:

an oscillator for converting DC energy into RF energy having a frequency f0;

a first antenna for transmitting the RF energy, the first antenna including a first inductor and a first capacitor that are connected together in series to form a series resonant circuit with a resonant frequency fT; and

a second antenna for receiving, by resonant magnetic coupling, at least a part of the RF energy that has been transmitted by the first antenna, the second antenna including a second inductor and a second capacitor that are 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,

the oscillator has a voltage step-up ratio Voc,

the first inductor has an inductance L1,

the second inductor has an inductance L2,

the second inductor is coupled with the first inductor by a resonant magnetic field at a coupling coefficient k which is set to be less than 0.5, and

the power transmission unit satisfies (L2/L1)≧

4(k/Voc)².

2. A power generator comprising:

a power generating section for outputting DC energy; and

a wireless power transmission unit, which is connected to the power generating section,

wherein the wireless power transmission unit includes;

an oscillator for converting the DC energy into RF energy having a frequency f0;

a first antenna for transmitting the RF energy, the first antenna including a first inductor and a first capacitor that are connected together in series to form a series resonant circuit with a resonant frequency fT; and

a second antenna for receiving, by resonant magnetic coupling, at least a part of the RF energy that has been transmitted by the first antenna, the second antenna including a second inductor and a second capacitor that are 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,

the oscillator has a voltage step-up ratio Voc,

the first inductor has an inductance L1,

the second inductor has an inductance L2,

the second inductor is coupled with the first inductor by a resonant magnetic field at a coupling coefficient k which is set to be less than 0.5, and

the power generator satisfies (L2/L1)≧

4(k/Voc)².

3. The power generator of claim 2, wherein the power generating section is a solar power generating section.

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

5. The power generator of claim 2, wherein when an output terminal of the second antenna is connected to a load that follows the second antenna, the output impedance Zoc of the oscillator and the input impedance Zin of the first antenna are substantially equal.

6. The power generator of claim 2, wherein when an output terminal of the oscillator is connected to an input terminal of the first antenna, the output impedance Zout of the second antenna is substantially equal to the input impedance of a load that follows the second antenna.

7. The power generator of claim 2, wherein (L2/L1)≧

100×

(k/Voc)² is satisfied.

8. The power generator of claim 2, wherein (L2/L1)≧

10000×

(k/Voc)² is satisfied.

9. The power generator of claim 2, wherein the power generating section and the first antenna are arranged outside of a building, and

wherein the second antenna is installed inside of the building.

10. The power generator of claim 2, wherein the first and second inductors both have an air-core spiral structure.

11. The power generator of claim 2, wherein L1<

L2 is satisfied.

12. The power generator of claim 2, wherein the number N2 of turns of the second inductor is greater than the number N1 of turns of the first inductor.

13. The power generator of claim 2, wherein the area of the second inductor is larger than an area of the first inductor.

14. The power generator of claim 13, wherein when the second inductor is projected onto the plane of the first inductor, the first inductor is included within an area defined by the projected profile of the second inductor.

15. The power generator of claim 13, wherein when the second inductor is projected onto the plane of the first inductor, the first inductor is located close to the periphery of an area defined by the projected profile of the second inductor.

16. A wireless power transmission unit comprising:

an oscillator for converting DC energy into RF energy having a frequency f0;

a first antenna for transmitting the RF energy, the first antenna including a first inductor and a first capacitor that are connected together in series to form a series resonant circuit with a resonant frequency fT;

a second antenna for receiving, by resonant magnetic coupling, at least a part of the RF energy that has been transmitted by the first antenna, the second antenna including a second inductor and a second capacitor that are connected in parallel with each other to form a parallel resonant circuit with a resonant frequency fR; and

a rectifier for converting the RF energy supplied from the second 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,

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,

the second inductor is coupled with the first inductor by a resonant magnetic field at a coupling coefficient k which is set to be less than 0.5, and

the power transmission unit satisfies (L2/L1)≧

4(k/(Voc×

Vrr))².

17. A power generator comprising:

a power generating section for outputting DC energy; and

a wireless power transmission unit, which is connected to the power generating section,

wherein the wireless power transmission unit includes;

an oscillator for converting the DC energy into RF energy having a frequency f0;

a first antenna for sending out the RF energy, the first antenna including a first inductor and a first capacitor that are connected together in series to form a series resonant circuit with a resonant frequency fT;

a second antenna for receiving, by resonant magnetic coupling, at least a part of the RF energy that has been transmitted by the first antenna, the second antenna including a second inductor and a second capacitor that are connected in parallel with each other to form a parallel resonant circuit with a resonant frequency fR; and

a rectifier for converting the RF energy supplied from the second 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,

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,

the second inductor is coupled with the first inductor by a resonant magnetic field at a coupling coefficient k which is set to be less than 0.5, and

the power generator satisfies (L2/L1)≧

4(k/(Voc×

Vrr))².

18. The power generator of claim 17, wherein the power generating section is a solar power generating section.

19. The power generator of claim 17, wherein when an output terminal of the rectifier is connected to a load that follows the rectifier, the output impedance Zoc of the oscillator and the input impedance Zin of the first antenna are substantially equal.

20. The power generator of claim 17, wherein when an output terminal of the oscillator is connected to an input terminal of the first antenna, the output impedance Zout of the rectifier is substantially equal to the input impedance of a load that follows the rectifier.

21. The power generator of claim 17, wherein (L2/L1)≧

100×

(k/(Voc×

Vrr))² is satisfied.

22. The power generator of claim 17, wherein (L2/L1)≧

2304×

(k/Voc)² is satisfied.

23. The power generator of claim 17, wherein (L2/L1)≧

10000×

(k/Voc)² is satisfied.

24. The power generator of claim 17, wherein the rectifier is a voltage doubler rectifier circuit with a voltage step-up ratio Vrr of at least two.

25. A power generation system comprising a number of power generators,

wherein in at least two of the power generators, their output terminals are connected in parallel with each other, and

wherein the at least two power generators are as defined by claim 17.