Electric power transmission device and electric power transmission method

• US 10,020,682 B2
• Filed: 08/21/2013
• Issued: 07/10/2018
• Est. Priority Date: 08/31/2012
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Tanomura, Masahiro, Yoshida, Shuhei, Shizuno, Kaoru, Kobayashi, Naoki, Fukuda, Hiroshi, Hama, Yoshinori
• Primary Examiner(s): Cole, Brandon S
• Application Number:
  US14/423,999
• Publication Number:
  US 20150303702A1
• Time in Patent Office: 1,784 Days
• Field of Search: 307104
• 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 comprising:

a power transmitting unit including a first coil having a first capacitance (C1) contained in a first dielectric member;

a power receiving unit including a second coil having a second capacitance (C2) contained in a second dielectric member; and

a highly conductive medium that entirely covers the power transmitting unit and the power receiving unit so as to form a third capacitance (C3) in connection with the power transmitting unit and the power receiving unit,

wherein the power transmitting unit and the power receiving unit are positioned close to each other with an interval distance (d) depending on the first capacitance, the second capacitance, and the third capacitance, and the interval distance between the power transmitting unit and the power receiving unit depends on a relationship of 30>

C3·

d/(C1+C2)>

0.5.

2. An electric power transmission device comprising:

a power transmitting unit including a first coil having a first capacitance (C1) contained in a first dielectric member;

a power receiving unit including a second coil having a second capacitance (C2) contained in a second dielectric member; and

a highly conductive medium that entirely covers the power transmitting unit and the power receiving unit so as to form a third capacitance (C3) in connection with the power transmitting unit and the power receiving unit,

wherein the power transmitting unit and the power receiving unit are positioned close to each other with an interval distance (d) depending on the first capacitance, the second capacitance, and the third capacitance, and impedance matching is implemented using a first variable capacitance (C1′

) for the power transmitting unit and a second variable capacitance (C2′

) for the power receiving unit so as to compensate for fluctuations of the third capacitance due to the interval distance being changed.

3. An electric power transmission device comprising:

a power transmitting unit including a first coil having a first capacitance (C1) contained in a first dielectric member;

a power receiving unit including a second coil having a second capacitance (C2) contained in a second dielectric member; and

a highly conductive medium that entirely covers the power transmitting unit and the power receiving unit so as to form a third capacitance (C3) in connection with the power transmitting unit and the power receiving unit,

wherein the power transmitting unit and the power receiving unit are positioned close to each other with an interval distance (d) depending on the first capacitance, the second capacitance, and the third capacitance, and a length (d1) of the first dielectric member along the first coil and an outer diameter (d2) of the first coil satisfy a relationship of d1/d2>

1.2.

4. An electric power transmission device comprising:

a power transmitting unit including a first coil having a first capacitance (C1) contained in a first dielectric member;

a power receiving unit including a second coil having a second capacitance (C2) contained in a second dielectric member; and

a highly conductive medium that entirely covers the power transmitting unit and the power receiving unit so as to form a third capacitance (C3) in connection with the power transmitting unit and the power receiving unit,

wherein the power transmitting unit and the power receiving unit are positioned close to each other with an interval distance (d) depending on the first capacitance, the second capacitance, and the third capacitance, and the highly conductive medium has conductivity greater than 1×

10<sup>−

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