ELECTRIC POWER TRANSMISSION DEVICE AND ELECTRIC POWER TRANSMISSION METHOD

• US 20150303702A1
• Filed: 08/21/2013
• Published: 10/22/2015
• Est. Priority Date: 08/31/2012
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: KOBAYASHI, Naoki, FUKUDA, Hiroshi, HAMA, Yoshinori, TANOMURA, Masahiro, YOSHIDA, Shuhei, SHIZUNO, Kaoru
• Granted Patent: US 10,020,682 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01F 27/02 Casings
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• 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 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H04B 13/02 Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy

Abstract

An electric power transmission device for wirelessly transmitting electric power in a highly conductive medium includes a power transmitting unit configured to wirelessly transmit electric power and a power receiving unit configured to intromit the wireless electric power transmitted from the power transmitting unit. The power transmitting unit and the power receiving unit include an electric power transmission coil and a containment member having a dielectric configured to cover the electric power transmission coil, and transmit the electric power by causing resonance at a frequency determined by impedance of the power transmitting unit, impedance of the power receiving unit, and impedance of the highly conductive medium.

Claims

1. An electric power transmission device for wirelessly transmitting electric power in a highly conductive medium, the electric power transmission device comprising:

a power transmitting unit configured to wirelessly transmit electric power; and

a power receiving unit configured to intromit the wireless electric power transmitted from the power transmitting unit,

wherein the power transmitting unit and the power receiving unit include

an electric power transmission coil; and

a containment member having a dielectric configured to cover the electric power transmission coil, and

transmit the electric power by causing resonance at a frequency determined by impedance of the power transmitting unit, impedance of the power receiving unit, and impedance of the highly conductive medium.

2. The electric power transmission device according to claim 1, wherein a capacitance component (C1 [pF]) constituting the impedance of the power transmitting unit, a capacitance component (C2 [pF]) constituting the impedance of the power receiving unit, a capacitance component (C3 [pF]) of capacitance formed by the power transmitting unit, the power receiving unit, and the highly conductive medium present between the power transmitting unit and the power receiving unit, and an interval distance (d [cm]) between the power transmitting unit and the power receiving unit satisfy a relationship of 30>

C3·

d/(C1+C2)>

0.5.

3. The electric power transmission device according to claim 1, wherein at least one of the power transmitting unit and the power receiving unit includes

an impedance adjustment unit configured to vary self-impedance.

4. The electric power transmission device according to claim 1, wherein a magnitude (d1 [cm]) of a direction along an electric power transmission coil surface of the containment member and an outer diameter (d2 [cm]) of the electric power transmission coil satisfy a relationship of d1/d2>

1.2.

5. The electric power transmission device according to claim 1, wherein the containment member includes

a first containment member having a first dielectric configured to cover the electric power transmission coil;

and

a second containment member having a second dielectric configured to cover the first containment member.

6. The electric power transmission device according to claim 5, wherein the containment member further includes

a covering unit having a third dielectric configured to cover the second containment member.

7. The electric power transmission device according to claim 5, wherein the second dielectric is constituted of a dielectric having the same specific gravity as the highly conductive medium.

8. The electric power transmission device according to claim 5, wherein a dielectric tangent of the first dielectric is less than or equal to a dielectric tangent of the second dielectric.

9. The electric power transmission device according to claim 5, wherein a specific dielectric constant of the first dielectric is less than or equal to a specific dielectric constant of the second dielectric.

10. The electric power transmission device according to claim 1, wherein the highly conductive medium has conductivity greater than 1×

10<sup>−

4</sup> and a specific dielectric constant greater than 1.

11. The electric power transmission device according to claim 1, wherein the highly conductive medium is any one of seawater, a river, fresh water, tap water, soil, and concrete.

12. The electric power transmission device according to claim 1,

wherein part or all of an electric field occurring in the highly conductive medium rotates approximately in parallel to an electric power transmission coil surface of the power transmitting unit or the power receiving unit, and

wherein part or all of a magnetic field occurring in the highly conductive medium is directed approximately in parallel to the electric power transmission coil surface of the power transmitting unit or the power receiving unit.

13. The electric power transmission device according to claim 12, wherein an interlinkage magnetic flux passing through the electric power transmission coil of the power transmitting unit and an interlinkage magnetic flux passing through the electric power transmission coil of the power receiving unit are directed in directions reverse to each other in a phase condition in which the magnetic field is maximized, thereby generating the magnetic field parallel to the electric power transmission coil surface.

14. The electric power transmission device according to claim 1,

wherein the power transmitting unit is mounted in a power supply source installed in seawater, a ship, or a submarine,

wherein the power receiving unit is mounted in a sensor installed in the seawater, the ship, or the submarine, and

wherein electric power transmission from the power transmitting unit to the power receiving unit is wirelessly performed.

15. The electric power transmission device according to claim 1, wherein electric power transmission is wirelessly performed from the power transmitting unit to the power receiving unit using the power transmitting unit and the power receiving unit in connection members of power cables placed in seawater.

16. The electric power transmission device according to claim 1, wherein electric power transmission and wireless communication are simultaneously performed using the power transmitting unit as a transmitter for transmitting information and using the power receiving unit as a receiver for transmitting information.

17. An electric power transmission method of wirelessly transmitting electric power in a highly conductive medium, the electric power transmission method comprising:

covering, by a containment member, an electric power transmission coil with a dielectric;

wirelessly transmitting, by a power transmitting unit, the electric power;

intromitting, by a power receiving unit, the transmitted wireless electric power; and

transmitting the electric power by causing resonance at a frequency determined by impedance of the power transmitting unit, impedance of the power receiving unit, and impedance of the highly conductive medium.