2. The electric power transmission device according to claim I, wherein a capacitance component (CI [pF]) constituting the impedance of the power transmitting unit, a capacitance component (C2 [pF]) constituting the impedance of the power 20 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]) bet\veen the power transmitting unit and the power receiving unit satisfy a relationship of 30>C3-d/(Cl+C2)>0.5. 25 45 3. The eiectric power transmission device according to claim 1 or 2, wherein at least one of the power transmitting unit and the power receiving unit includes an impedance adjustment unit configured to varj' seif-impedance. 5 4. The electric power transmission device according to any one of claims 1 to 3, wherein a magnitude (dl [cm]) of a direction along an electric power transmission coil surface of the containnient member and an outer diameter (d2 [cm]) of the electric power transmission coil satisfy a relationship of dl/d2>1.2. 10 5. The electric power transmission device according to any one of claims I to 4, wherein the containment member includes a fust 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 15 the first containment member.

6. The electric power transmission device according to claim 5, wherein the containment member further inchides a covering unit having a third dielectric configured to cover the second 20 containment member.

7. The electric power transmission device according to claim 5 or 6, wherein the second dielectric is constituted of a dielectric having the same specific gravit)' as the highly conductive medium. 25 46 8. The electric power transmission device according to any one of claims 5 to 7, wherein a dielectric tangent of the first dielectric is less than or equal to a dielectric tangent of the second dielectric. 5 9. The electric power transmission device according to any one of claims 5 to 8, 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 any one of claims 1 to 10 9, wherein the highly conductive medium has conductivity greater than 1x10^'' and a specific dielectric constant greater than 1.

11. The electric power transmission device according to any one of claims 1 to 10, wherein the highly conductive medium is any one of seawater, a river, fresh water, 15 tap water, soil, and concrete.

12. The electric power transmission device according to any one of claims 1 to 11, wherein part or all of an electric field occurring in the highly conductive 20 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 higlily conductive medium is directed approximately in parallel to the electric power transmission coil surface of the power transmitting unit or the power receiving unit. 25 47

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 5 each other in a phase condition in which the magnetic field is maxhnized, thereby generating t!ie magnetic field parallel to the electric power transmission coil surface.

14. The electric power transmission device according to any one of claims 1 to 13, 10 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 ixom the power transmitting unit to the 15 power receiving unit is wirelessly performed.

15. The electric power transmission device according to any one of claims 1 to 14, wherein electric power transmission is wirelessly performed from the power transmitting unit to the power receiving unit using the power transmitting unit and the 20 power receiving unit in connection members of power cables placed in seawater.

16. The electric power transmission device according to any one of claims 1 to 15, wherein electric power transmission and wireless communication are simultaneously performed using the power transmitting unit as a transmitter for transmitting information 25 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: 5 covering, by a contaiimient 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 10 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 higlily conductive medium.

TECHNICAL FIELD
[0001]
The present invention relates to an electric power transmission device and an
electric power transmission method.
10 BACKGROUND ART
[0002]
In recent years, the spread of resource exploration devices in the sea or marine earthquake sensor networks for early detection of earthquakes has progressed and there has been a high need for electric power supply means for these devices. It is desirable 15 to use wireless electric power transmission technology as the electric power supply means for these devices because they are surrounded by seawater. This is because enabling wireless transmission of electric power obviates the need to expose a metal plug for electric power supply and the possibility of short-circuiting in seawater, which has a conductivity of about 4 Siemens per meter (S/m). 20 [0003]
In general, a coil obtained by winding a wire a pluralit)' of times is used as means for wirelessly transmitting and receiving electric power. A magnetic flux interlinking the coil is generated by applying alternating current (AC) power to the coil of the power transmitting unit. Further, this magnetic flux generates an induced current 25 in the coil of the power receiving unit by performing interlinking with the coil of the

2 power receiving unit and the transmission of electric power is performed.
[0004]
Incidentally, in wireless technology, for example, technology for perfomiing communication between a terminal device main body and a detachable electronic device 5 such as a memory card using a wireless millimeter wave signal is disclosed in Patent Document 1. In addition, technology for improving inductance values of a power transmittmg unit and a power receiving unit and increasing a distance of electric power transmission using a magnetic member is disclosed in Patent Document 2. In addition, technology for improving mutual inductances of a power transmitting unit and a power 10 receiving unit and increasing a distance of transmission by causing resonance (magnetic field resonance) at t!ie same frequency using a coil having a high quality (Q) value is disclosed in Patent Document 3. [Documents of the prior art] [Patent Documents] 15 [0005]
[Patent Document 1]
Japanese Unexamined Patent Application, First Publication No. 2011-022640 [Patent Document 2]
Japanese Patent No. 4772744 20 [Patent Document 3]
Japanese Unexamined Patent Application, First Publication No. 2012-504387
DISCLOSURE OF INVENTION [Problejiis to be solved by the invention] 25 [0006]

3 However, in the wireless electric power transmission technology using the
conventional electromagnetic induction teclinology, it is necessary to shorten a distance
between a coil of a power transmitting unit and a coil of a power receiving unit almost to
the point of contact so as to efficiently perform electric power transmission. Thus, for
5 example, it is difficult to stably supply electric power because alignment of a ship is not
performed with high precision.
[0007]
On the other hand, even in the above-described long-distance transmission
technology, it is obvious that only low electric power transmission efficiency is obtained
10 even when the long-distance transmission technology in the air is applied to seawater. This is based on the fact that conductivit}' and dielectric constants are significantly different between air and seawater and a mechanism of electric power transmission in the media is different in electric power transmission in the air and electric power transmission in seawater. Also, the conductivity' of air is 0 S/m and the specific
15 dielectric constant thereof is about 1. On the other hand, the conductivity of seawater is about 4 S/m and the specific dielectric constant thereof is about 81. [0008]
Here, physical differences between the case in which wireless electric power is propagated in the air and the case in which the wireless electric power is propagated in
20 seawater will be briefly described.
First, in the case of electric power transmission in the air, there is substantially no energy consumed during the propagation in the medium (air). In this case, factors decreasing electric power transmission efficiency mainly include conductor loss in a coil, matching loss between the power transmitting unit and the power receiving unit,
25 reflection loss such as a leakage magnetic flux, and radiation loss. In particular, in

4 Patent Document 2, radiation loss is effectively suppressed by adopting a non-radiative
phenomenon in which energy is stored in the vicinity of the power transmitting/receiving
unit using a coil having a high Q value.
[0009]
5 On the other hand, when the medium is seawater, because seawater has fixed
conductivity', loss occurs when energy is propagated in the medium. Factors causing the
energy loss are based on the conductivit}' of seawater and an electric field occurring in
seawater. That is, the loss occurs when a potential gradient proportional to a product of
the conductivity and the electric field occurs in seawater. In addition, because seawater
10 has high conductivity', energy lost without reaching an opposite power receiving unit increases when the energy is non-directionally transmitted from the power transmitting unit in seawater. Therefore, in order to efficiently perform electric power transmission in seawater, it is necessary' to have directivity in which opposite coil surfaces are connected and form a flow of energy substantially perpendicular to the coil surface.
15 [0010]
In light of the differences of the above-described propagation mechanisms, it is particularly difficult to transmit a millimeter wave signal shown in Patent Document 1 in a highly conductive medium such as seawater. For example, because an attenuation distance in seawater is 100 j.un or less in the case of a millimeter wave of 60 GHz, it is
20 impossible to perfonn propagation of 10 cm or more in seawater. [0011]
In addition, even when long-distance transmission is implemented in seawater using a magnetic member or resonance as siiown in Patent Document 2, the magnetic flux increases, the number of electric field components radiated in the seawater increases
25 with the magnetic flux, and electric power transmission efficiency does not increase as a

5 result. Fiiithei; because of a non-radiative phenomenon, it is fiindanientally difficult to
implement long-distance transmission in a medium having high conductivity.
[0012]
In particular, in the case of the conventional magnetic field resonance
5 technology as shown in Patent Document 3, it is possible to efficiently perform energy
transmission only by making resonant frequencies of the coil of the power transmitting
unit and the coil of the power receiving unit equal in the air. However, because the
specific dielectric constant is as large as 81 in seawater, the influence of impedance
between the power transmitting unit and the power receiving unit is large and it is
10 difficult to perform energy transmission using only a simple resonance phenomenon of
the power transmitting/receiving unit.
[0013]
Further, various tj'pes of media as shown in a table of FIG. 27 also have
relatively high conductivit>' and specific dielectric constants. Therefore, a similar
15 problem may occur even when electric power is transmitted not only in seawater but also
in other such media.
[0014]
Therefore, the present invention provides an electric power transmission device
and an electric power transmission method tor solving the above-described problems.
20 [Means for solving the problem]
[0015]
Tiie present invention has been made to solve the above-described problems and
is an electric power transmission device for wirelessly transmitting electric power in a
highly conductive medium, the electric power transmission device including: a power
25 transmitting unit configured to wirelessiy transmit electric power; and a power receiving

6 uait configured to intromit the wireless electric power transmitted from the power
transmitting unit, wherein tlie 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
5 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 niediun).
[0016]
In addition, the present invention is an electric power transmission method of
10 wirelessiy transmitting electric power in a highly conductive medium, the electric power transmission method including: covering, by a containment member, an electric power transmission coil with a dielectric; wirelessiy 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
15 determined by impedance of the power transmitting unit, impedance of the power receiving unit, and impedance of the highly conductive medium. [Effects of the hwention] [0017]
According to the present invention, it is possible to minimize the disappearance
20 of electromagnetic energy diffused in a highly conductive medium even when a power transmitting unit and a power receiving unit are in a relatively separated neighboring field and consequently long-distance transmission is enabled in wireless electric power transmission in the highly conductive medium such as seawater.
25 BRIEF DESCRIPTION OF DRAWINGS

7 [0018]
FIG. 1 is a diagram illustrating a configuration of an electric power transmission
device according to a first embodiment of the present invention.
FIG. 2 is an equivalent circuit diagram of wireless electric power when the
5 wireless electric power is propagated from a power transmitting unit to a power receiving
unit according to the first embodiment of the present invention.
FIG. 3 is a graph illustrating influences of capacitance components of the power
transmitting unit and the power receiving unit and a capacitance component generated
between the power transmitting and receiving units on electric power transmission
10 efficiency according to the first embodiment of the present invention.
FIG. 4A is a graph illustrafing influences of a diameter of a power transmission
coil and a dimensional ratio of a power-transmitting-side containment member on electric
power transmission efificieney according to the first embodiment of the present invention.
FIG. 4B is a sectional view illustrating the diameter of the power transmission
15 coil and the dimensional ratio of the power-transmitting-side containment member
according to the first embodiment of the present invention.
FIG. 5 is a diagram illustrating an electric field vector and a magnetic field
vector in the electric power transmission device according to the first embodiment of the
present invention.
20 FIG. 6 is a diagram illustrating a Poynling vector (energy flow) generated based
on the electric field vector and the magnetic field vector in the electric power
transmission device according to the first embodiment of the present invention.
FIG. 7 is a diagram illustrating a configuration of the power transmission device
according to a second embodiment of the present invention.
25 FIG. 8 is a graph illustrating an influence of a ratio between a dielectric tangent

8 of a first dielectric and a dielectric tangent of a second dielectric on electric power
transmission efficiency according to the second embodiment of the present invention.
FIG. 9 is a graph illustrating influences of a specific dielectric constant of the
first dielectric and a specific dielectric constant of the second dielectric on the electric
5 power transmission efficiency according to the second embodiment of the present
invention.
FIG. 10 is a diagram illustrating an electric power transmission device according
to a third embodiment of the present invention.
FIG 11 is a diagram illustrating a first example in the third embodiment of the
10 present invention.
FIG 12 is a diagram illustrating a second example in the third embodiment of
the present invention.
FIG. 13 is a diagram illustrating a third example in the third embodiment of the
present invention.
15 FIG. 14 is a model diagram for simulations for verifying the effect of the electric
power transmission device of the first example in the third embodiment of the present
invention.
FIG. 15 is a schematic top view of the power transmitting unit in the first
example of the third embodiment of the present invention.
20 FIG 16 is a graph illustrating simulation results of electric power transmission
efficiency in the first example of the third embodiment of the present invention.
FIG I7A is a sectional side view illustrating an electric field vector in the
vicinity of the power transmitting unit and the power receiving unit in the first example
of the third embodiment of the present invention.
25 FIG. 17B is a sectional pian view illustrating the electric field vector in the

9 vicinity of the power transmitting unit and the power receiving unit in the first example
of the third embodiment of the present invention.
FIG. 18A is a sectional side view ilUistrating a magnetic field vector in the
vicinity of the power transmitting unit and the power receiving unit in the first example
5 of the third embodiment of the present invention.
FIG. 18B is a sectional plan viewillustratingthemagneticfieid vector in the
vicinit)' of the power transmitting unit and the power receiving unit in the first example
of the third embodiment of the present invention.
FIG. 19A is a sectional side view illustrating a Poynting vector in the vicinity of
10 the power transmitting unit and the power receiving unit in the first example of the third
embodiment of the present invention.
FIG. 19B is a sectional plan view illustrating the Poynting vector in the vicinity
of the power transmitting unit and the power receiving unit in the first example of the
third embodiment of the present invention.
15 FIG. 20A is a sectional side view illustrating a Poynting vector in the air in the
first example of the third embodiment of the present invention.
FIG. 20B is a sectional plan view illustrating a Poynting vector in the air in the
first example of the third embodiment of the present invention.
FIG. 21A is a sectional side view illustrating a Poynting vector in the air when
20 conventional magnetic field resonance technology is used.
FIG 21B is a sectional plan view illustrating a Poynting vector in the air when
the conventional magnetic field resonance technology is used.
FIG 22 is a model diagram for simulations for verifying the effect of the electric
power transmission device of the second example in the third embodiment of the present
25 invention.

10 FIG. 23 is a model diagram of a spiral coil viewed from the top surface in the
second example of the third embodiment of the present invention.
FIG. 24 is a model diagram of the spiral coil viewed from the side surface in the
second example of the third embodiment of the present invention.
5 FIG. 25 is a model diagram of a loop coil viewed from the top surface in the
second example of the third embodiment of the present invention.
FIG. 26 is a model diagram of the loop coil viewed from the side surface in the
second example of the third embodiment of the present invention.
FIG. 27 is a diagram illustrating a table in which conductivities of various t>'pes
10 of media related to electric power transmission and specific dielectric constants are
summarized.
FIG. 28 is a model diagram for simulations for verifying the effect of the electric
power transmission device 6 as a third example in the third embodiment of the present
invention.
15 FIG. 29 is a side view of the power transmitting unit in the third example of the
third embodiment of the present invention.
FIG. 30 is a model view of a spiral coil in the third example of the third
embodiment of the present invention viewed from the power receiving unit side.
FIG. 31 is a model view of the spiral coil in the tliird example of the third
20 embodiment of the present invention viewed from the power receiving unit side.
FIG. 32 is a model view of a spiral coil in the third example of the third
embodiment of the present invention viewed from the power transmitting unit side.
FIG. 33 is a model view of the spiral coil in the third example of the third
embodiment of the present invention viewed from the power transmitting unit side.
25 FIG 34 is a graph illustrating simulation results of the electric power

u
transmission efficiency in the third example of tlie third embodiment of the present invention.
EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0019]
5
Hereinafter, an electric power transmission device according to the first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of the electric power transmission device according to the first embodiment.
10 in FIG. 1, an electric power transmission device 1 includes a power transmitting
unit 11 and a power receiving unit 12. In addition, the power transmitting unit 11 and the power receiving unit 12 are covered with a highly conductive medium 13. The power transmitting unit 11 includes a power transmission coil HI and a power-transmitting-side containment member 112 constituted of a dielectric configured
15 to cover the power transmission coil HI. In addition, like the power transmitting unit H, the power receiving unit 12 includes a power reception coil 121 and a power-receiving-side containment member 122. Each of the power transmission coil HI and the power reception coi! 121 is obtained by winding a conductor such as a copper wire a plurality of times. Although a helical coil, a spiral coil, or the like is
20 generally used as the power transmission coil 111 and the power reception coil 121, this embodiment is not limited thereto.
Also, here, the power transmitting unit and the power receiving unit in the electric power transmission device are collectively referred to as an electric power transmission unit. In addition, the power transmission coil and the power reception coil
25 are collectively referred to as an electric power transmission coil. Flere, the power

12 transmitting unit may include a fiinction as tlie power receiving unit and the power
receiving unit may include a flmction as the power transmitting unit. In addition, the
power transmitting unit and the power receiving unit have the same configuration.
[0020]
5 The power-transmitting-side containment member 112 and the
power-receiving-side containment member 122, for example, include a dielectric having
adielectrictangent of 0.01 or less in a specific dielectric constant of about 2 to 10 such
as polyethylene, polyimide, polyamide, fluorine resin, or acryl.
[0021]
10 In addition, although the highly conductive medium is assumed to be seawater
in each embodiment, the present invention is not limited thereto. For example, the
highly conductive medium may be a matter having a specific dielectric constant greater
than 1 at a conductivity of 1x10"'' S/m or more such as a river, fresh water, tap water, soil,
or concrete shown in the table of FIG. 27. 15 [0022]
Here, an equivalent circuit when wireless electric power transmitted from the
power transmitting unit 11 is propagated to the power receiving unit 12 is illustrated in
FIG. 2.
FIG. 2 is an equivalent circuit diagram for the wireless electric power when the 20 wireless electric power is propagated from the power transmitting unit 11 to the power
receiving unit 12.
Tlie power transmitting unit 11 and the power receiving unit 12 flirther include a
power-transmitting-side impedance adjustment unit 113 and a power-receiving-side
impedance adjustment unit 123 configured to adjust impedance of the power 25 transmission coil 111 or the power reception coil 121. Here, the impedance of the

13 power transmission coil 111 in the power transmitting unit 11 mainly includes an
inductance component LI and a capacitance component CI, and these are uniquely
determined by a coil sliape, the number of turns, a thickness of a copper wire, and a
dielectric constant and size of a dielectric constituting the power-transmitting-side
5 containment member 112. Likewise, the impedance of the power reception coil 121 in
the power receiving unit 12 also includes an inductance component L2 and a capacitance
component C2.
Also, in the present document, the power-transmitting-side impedance
adjustment unit and the power-receiving-side impedance adjustment unit are collectively
10 referred to simply as an impedance adjustment unit. [0023]
AC power supplied to the power transmitting unit 11 is propagated in an equivalent circuit constituted of the above-described LI, L2, CI, and C2, L3, and C3, and propagated to the power receiving unit 12. t.Here, L3 is a mutual inductance component
15 in the power transmission coi! Ill and the power reception coil 121 and C3 is a
capacitance component configured in the power transmitting unit 11, the power receiving
unit 12, and the highly conductive medium 13.
[0024]
In terms of transmission efficiency at the time of propagation, whether
20 impedance matching (resonance) is achieved at a frequency of AC power to be
propagated through a propagation path is important. Therefore, as illustrated in FIG. 2, it is possible to perform adjustment so that impedance matching is obtained at an arbitrary frequency by adding each of a capacitance component CT of variable capacitance of the power-transmitting-side impedance adjustment unit 113 and a
25 capacitance component C2' of variable capacitance of the power-receiving-side

14 impedance adjustnientunit 123. Thus, even when a positional relationship between the
power transmitting unit 11 and the power receiving unit 12 during power transmission
varies and a value of C3 fluctuates, it is possible to supply stable electric power by
maintaining resonance if CI' and C2' are appropriately adjusted to compensate for this
5 fluctuation.
A varactor diode (variable capacitance diode) can be used in a variant part of
capacitance and a pluralit}' of capacitances can be configured to be combined with a
switch transistor.
[0025]
10 Here, in the following description, a combination capacitance component of a
capacitance component provided in the power transmission coil 111 itself and a capacitance component of variable capacitance is newly set as CI. This will be described as the capacitance component CI constituting the impedance of the power transmitting unit U. Likewise, a combination capacitance component of a capacitance
15 component of the power reception coil 121 itself and a capacitance component of variable capacitance is newly set as C2. This will be described as the capacitance component C2 constituting the impedance of the power receiving unit 12. [0026]
Here, in the electric power transmission device 1 of the first embodiment, il is
20 possible to particularly obtain high electric power transmission efficiency when a
predetermined condition is satisfied in terms of a capacitance component CI constituting the impedance of the power transmitting unit 11, a capacitance component C2 constituting the impedance of the power receiving unit 12, a capacitance component C3 of capacitance formed by the power transmitting unit 11, the power receiving unit 12, and
25 the highly conductive medium 13 present between the power transmitting unit 11 and the

15 power receiving unit 12, and an interval distance d between the power transmitting unit
and the power receiving unit.
[0027]
FIG. 3 is a graph illustrating influences of capacitance components of the power 5 transmitting unit 11 and the power receiving unit 12 and a capacitance component generated between the power transmitting and receiving units on electric power transmission efficiency.
From the graph ilhistrated in FIG. 3, it can be seen that particularly high electric power transmission efficiency is obtained when the above-described CI [pF], C2 [pF], 10 C3 [pF], and d [cm] satisfy the following condition. [0028]
[Math 1]
(C1 + C2)
[0029]
15 Also, according to three-dimensional electromagnetic field simulations, in this
embodiment, it is possible to satisfy Formula (I) under the condition that areas of the power transmission coil 111 and the power reception coil 121 be about 10 cm to 30 cm and the distance d between the power transmitting unit 11 and the power receiving unit 12 be about 5 cm to 30 cm.
20 [0030]
In addition, in the first embodiment, it is possible to obtain particularly high electric power transmission efficiency when a dimensional ratio of the power transmission coil 111 and the power-transmitting-side containment member 112 and a

16 dimensional ratio of the power reception coil 121 and the power-recciving-side
containment member 122 satisfy a predetermined condition.
[0031]
FIG. 4A is a graph illustrating influences of an outer diameter of the power
5 transmission coil 111 and a dimensional ratio of the power-transmitting-side containment
member 112 on electric power transmission efficiency. According to FIG. 4A, it is
possible to obtain electric power transmission efficiency which is at least 5% more than 1,
that is a minimum ratio capable of being produced, by setting a ratio dl/d2 to 1.2 or more
in the relationship of the magnitude of the direction along a coil surface of the
10 power-transmitting-side containment member 112 and an outer diameter d2 (FIG. 4B) of the power transmission coil 111. Further, when a high electric power transmission efficiency of 10% or more is desired to be obtained, it is preferable that a value of the ratio dl/d2 be 1.4 or more.
Also, it is possible to obtain similar effects even in the diameter of the power
15 reception coil 121 in the power receiving unit 12 and the dimensional ratio of the power-receiving-side containment member 122. In addition, if both the power transmitting unit 11 and the power receiving unit 12 satisfy the above-described condition, it is possible to obtain a greater effect. [0032]
20 Next, a specific operation of the electric power transmission device 1 according
to this embodiment will be sequentially described.
First, in the power transmitting unit 11, an AC power supply (not illustrated) outputs AC power at a predetermined frequency. Next, the output AC power is supplied to the power transmission coil 111 and the power transmission coil 111 transmits the AC
25 power as electromagnetic energ)' to the outside (the highly conductive medium 13).

17 Next, the power receiving unit 12 intromits the transmitted electromagnetic energy to the
power reception coil 121. Here, the power-transmitting-side impedance adjustment unit
113 and the power-receiving-side impedance adjustment unit 123 adjust combination
impedance of impedances of the power transmitting unit 11, the power receiving unit 12,
5 and the highly conductive medium 13 so that resonance is at a frequency of electric
power to be transmitted. Electric power intromitted by the power reception coil 121 is
supplied to a target load (for example, a battery or the like) and electric power
transmission is completed.
[0033]
10 In the electric power transmission device 1 according to the first embodiment, it
is possible to maximize electric power to be intromitted to the power reception coil 121 by causing resonance in the combination impedance of the impedances of the power transmitting unit 11, the power receiving unit 12, and the higlily conductive medium 13. In addition, the power-transmitting-side containment member 112 and the
15 power-receiving-side containment member 122 prevent the electric field from extending to the highly conductive medium 13 and therefore there is an effect of minimizing the disappearance of electromagnetic energy diffused into the highly conductive medium 13. [0034]
FIG. 5 is a diagram illustrating an electric field vector and a magnetic field
20 vector in the electric power transmission device 1 according to the first embodiment and FIG. 6 is a diagram illustrating a Poynting vector (energy flow) generated based on the electric field vector and the magnetic field vector.
Here, schematic diagrams illustrating simulation results of the electric field and the magnetic field generated between the power transmitting unit 11 and the power
25 receiving unit 12 at the time of electric power transmission are illustrated in Figs. 5 and 6.

18 As illustrated in FIG. 5, in the electric power transmission device 1 of this embodiment,
the electric field and the magnetic field can be substantially parallel to a coil surface.
As a result, as illustrated in FIG. 6, it is possible to generate a substantially perpendicular
Poynting vector (electromagnetic energy flow) from the power transmitting unit 11 to the
5 power receiving unit 12.
[0035]
From the above, according to the electric power transmission device 1 based on
the first embodiment, it is possible to minimize the disappearance of electromagnetic
energy diffused into a highly conductive medium even when the power transmitting unit
10 11 and the power receiving unit 12 are in a relatively separated neighboring field and
consequently long-distance transmission is enabled in wireless electric power
transmission in the highly conductive medium such as seawater.
[0036]

15 FIG 7 is a diagram illustrating a configuration of the electric power transmission
device according to the second embodiment of the present invention.
Next, the electric power transmission device according to the second
embodiment will be described with reference to the drawings.
In FIG. 7, the electric power transmission device 2 includes a power transmitting
20 unit 21 and a power receiving unit 22. in addition, the power transmitting unit 21 and
the power receiving unit 22 are covered with a highly conductive medium 23. The
power transmitting unit 21 includes a power transmission coil 211 and a first
power-transmitting-side containment member 212 constituted of a first dielectric
configured to cover the power transmission coil 211, and fiirther includes a second
25 power-transmitting-side containment member 213 constituted of a second dielectric

19 configured to cover the fust power-traiismitting-side containment member 212. In
addition, like the power transmitting unit 21, the power receiving unit 22 includes a
power reception coil 221, a first power-receiving-side containment member 222, and a
second power-receiving-side containment member 223.
5 Also, in the present document, the first power-transmitting-side containment
member and the first power-receiving-side containment member are collectively referred
to as a first containment member and the second power-transmitting-side containment
member and the second power-receiving-side containment member are collectively
referred to as a second containment member.
10 [0037]
The first power-transmitting-side containment member 212, the second power-transmitting-side containment member 213, the first power-receiving-side containment member 222, and the second power-receiving-side containment member 223, for example, include a dielectric having a dielectric tangent of 0.01 or less at a specific
15 dielectric constant of about 2 to 10 such as polyethylene, polyimide, polyamide, fluorine resin, or acryl. [0038]
In addition, in the electric power transmission device 2 of the second embodiment, the specific dielectric constant of the first dielectric constituting the first
20 power-transmitting-side containment member 212 and the specific dielectric constant of the second dielectric constituting the second power-transmitting-side containment member 213 may be different or the same. In addifion, the dielectric tangent of the first dielectric constituting the first power-transmitting-side containment member 212 and the dielectric tangent of the second dielectric constituting the second power-transmitting-side
25 containment member 213 may be different or the same. The same is true for the first

20 dielectric constituting the first power-receiving-side containment member 222 and the
second dielectric constituting the second power-receiving-side containment member 223.
[0039]
In addition, although both the power transmitting unit 21 and the power
5 receiving unit 22 are disclosed as structures having the first containment member and the
second containment member in FIG. 7 illustrating the configuration of the electric power
transmission device 2, it is also possible for only one of the power transmitting unit 21
and the power receiving unit 22 to have a structure having the first containment member
a!id the second containment member in the second embodiment.
10 Further, an impedance adjustment unit described in the first embodiment may
also be provided in the electric power transmission device 2 of this embodiment.
[0040]
Here, in the electric power transmission device 2 of the second embodiment^ it is
possible to obtain higher electric power transmission efficiency when the dielectric
15 tangents of the dielectrics constituting the first power-transmitting-side containment
member 212 and the second power-transmitting-side containment member 213 satisfy a
predetermined condition.
[0041]
FIG. 8 is a graph illustrating an influence of a ratio between the dielectric
20 tangent of the first dielectric and the dielectric tangent of the second dielectric on electric
power transmission efficiency.
As illustrated in FIG. 8, it can be seen that higher electric power transmission
efficiency is obtained by making the dielectric tangent of the second dielectric greater
than the dielectric tangent of the first dielectric. This enables an efi:ect of preventing the
25 electric field from extending to the highly conductive medium 23 by the second dielectric

21 constituting the second powei-transmitting-side containment member 213 (second
powei-receiving-side containment member 223) to be obtained and is based on an effect
of reducing dielectric loss in the vicinity of the power transmission coil 211 (power
reception coil 221) by reducing the dielectric tangent of the first dielectric constituting
5 the first power-transmitting-side containment member 212 (first power-receiving-side
containment member 222).
[0042]
In addition, in the electric power transmission device 2 of the second
embodiment, it is also possible to obtain higher electric power transmission efficiency
10 when dielectric constants of the dielectrics constituting the first power-transmitting-side
containment member 212 and the second power-transmitting-side containment member
213 satisfy a predetermined condition.
[0043]
FIG. 9 is a graph illustrating influences of a specific dielectric constant of the
15 first dielectric and a specific dielectric constant of the second dielectric on the electric
power transmission efficiency.
As illustrated in FIG. 9, it can be seen that higher electric power transmission
efficiency is obtained by making the specific dielectric constant of the second dielectric
greater than the specific dielectric constant of the first dielectric.
20 [0044]
Next, a specific operation of the electric power transmission device 2 according
to the second embodiment will be sequentially described.
First, in the power transmitting unit 21, an AC power supply (not illustrated)
outputs AC power at a predetermined frequency. Next, the output AC power is supplied
25 to the power transmission coil 211 and the power transmission coil 211 transmits the AC

22 power as electromagnetic energ)' to the outside (the highly conductive medium 23).
Next, the power receiving unit 12 intromits the transmitted electromagnetic energy to the
power reception coil 221. Here, combination impedance of impedances of the power
transmitting unit 21, the power receiving unit 22, and the highly conductive medium 23
5 is adjusted so that resonance is at a frequency of electric power to be transmitted.
Electric power intromitted by the power reception coil 221 is supplied to a target load
(for example, a battery or the like) and electric power transmission is completed.
[0045]
In the electric power transmission device 2 according to the second embodiment,
10 it is possible to maximize electric power to be intromitted to the power reception coil 221
by causing resonance in the combination impedance of the impedances of the power
transmitting unit 21, the power receiving unit 22, and the highly conductive medium 23.
In addition, the second power-transmitting-side containment member 213 and
the second power-receiving-side containment member 223 prevent the electric field from
15 extending to the highly conductive medium 23 and therefore there is an effect of
minimizing the disappearance of electromagnetic energy diffused into the highly
conductive medium 23.
Thus, there is an effect that the first power-transmitting-side containment
member 212 and the first power-receiving-side containment member 222 reduce
20 dielectric loss in the vicinity of the power transmission coil 211 and the power reception
coi! 221.
[0046]
As shown above, the electric power transmission device 2 according to the
second embodiment can obtain high electric power transmission efficiency as in the
25 electric power transmission device 1 according to the first embodiment.

23 [0047]

FIG. 10 is a diagram illustrating a configuration of an electric power
transmission device according to the third embodiment of the present invention.
5 Next, the electric power transmission device according to the third embodiment
will be described with reference to the drawings.
In FIG. 10, the electric power transmission device 3 includes a power
transmitting unit 31 and a power receiving unit 32. In addition, the power transmitting
unit 31 and the power receiving unit 32 are covered with a highly conductive medium 33.
10 The power transmitting unit 31 includes a power transmission coil 311 and a first
power-transmitting-side containment member 312 constituted of a first dielectric
configured to cover the power transmission coil 311, a second power-transmitting-side
containment member 313 constituted of a second dielectric configured to cover the first
power-transmitting-side containment member 312, and a third power-transmitting-side
15 containment member 314 constituted of a third dielectric configured to cover the second
power-transmitting-side containment member 313. In addition, like the power
transmitting unit 31, the power receiving unit 32 inchides a power reception coil 321, a
first power-receiving-side containment member 322, a second power-receiving-side
containment member 323, and a third power-receiving-side containment member 324.
20 Also, in the present document, the third power-transmitting-side containment
member and the third power-receiving-side containment member are collectively referred
to as a covering member.
[0048]
The first power-transmitting-side containment member 312, the third
25 power-transmitting-side containment member 314, the first power-receiving-side

24 containment member 322, and the third power-receiving-side containment member 324,
for example, include a dielectric having a dielectric tangent of O.OI or less at a specific
dielectric constant of about 2 to 10 such as polyethylene, polyimide, polyamide, fluorine
resin, or nciyl.
5 [0049]
In addition, the second power-transmitting-side containment member 313 and
the second power-receiving-sidc containment member 323 are constituted of a liquid (for
example, pure water or distilled water) having the same specific gravity as the highly
conductive medium 33 (seawater) and having low conductivity. Thus, the second
10 power-transmitting-side containment member 313 and the second power-receiving-side containment member 323 can provide neutral buoyancy in the highly conductive medium 33 (in seawater). If the second power-transmitting-side containment member 313 or the second power-receiving-side containment member 323 can provide neutral buoyanc}', cost reduction can be promoted because it is unnecessary to provide a particular
15 mechanism for adjusting a specific gravit>', for example, when the electric power transmission device 3 floats and sinks in the seawater.
In addition, the third power-transmitting-side containment member 314 and the third power-receiving-side containment member 324 constituted of the third dielectric physically confine the second power-transmitting-side containment member 313 and the
20 second power-receiving-side containment member 323 which are liquid. [0050]
In addition, in the electric power transmission device 3 of the third embodiment, the specific dielectric constant of the first dielectric constituting the first power-transmittmg-side containment member 312, the specific dielectric constant of the
25 second dielectric constituting the second power-transmitting-side containment member

25 313, and the specific dielectric constant of the third dielectric constituting the third
power-transmitting-side containment member 314 may be different or the same. In
addition, the dielectric tangent of the first dielectric constituting the first
power-transmitting-side containment member 312, the dielectric tangent of the second
5 dielectric constituting the second power-transmitting-side containment member 313, and
the dielectric tangent of the third dielectric constituting the third power-transmitting-side
containment member 314 may be different or the same. The same is true for the first
dielectric constituting the first power-receiving-side containment member 322, the
second dielectric constituting the second power-reeeiving-side containment member 323,
10 and the third dielectric constituting the third power-receiving-side containment member 324. [0051]
In addition, althougli both the po\\'er transmitting unit 31 and the power receiving unit 32 are disclosed as structures having the first containment member, the
15 second containment member, and the third containment member in FIG. 10 illustrating the configuration of the electric power transmission device 3, it is also possible for only one of the power transmitting unit 31 and the power receiving unit 32 to have a structure having the first containment member, the second containment member, and the third containment member in this embodiment.
20 Also, an impedance adjustment unit described in the first embodiment may also
be provided in the electric power transmission device 3 according to the third embodiment. [0052]
Next, a specific operation of the electric power transmission device 3 according
25 to the third embodiment will be sequentially described.

26 First, in the power transmitting unit 31, an AC power supply (not illustrated)
outputs AC power at a predetermined frequency. Next, the output AC power is supplied
to the power transmission coil 311 and the power transmission coil 311 transmits the AC
power as electromagnetic energy to the outside (the highly conductive medium 33).
5 Next, the power receiving unit 32 intromits the transmitted electromagnetic energy to the
power reception coil 321. Here, combination impedance of impedances of the power
transmitting unit 31, the power receiving unit 32, and the highly conductive medium 33
is adjusted so that resonance is at a frequency of electric power to be transmitted.
Electric power intromitted by the power reception coil 321 is supplied to a target load
10 (for example, a battery or the like) and electric power transmission is completed. [0053]
In the electric power transmission device 3 according to the third embodiment, it is possible to maximize electric power to be intromitted to the power reception coil 321 by causing resonance in the combination impedance of the impedances of the power
15 transmitting unit 31, the power receiving unit 32, and the highly conductive medium 33. In addition, the second power-transmitting-side containment member 313 and the second power-receiving-side containment member 323 prevent the electric field from extending to the highly conductive medium 33 and therefore there is an effect of minimizing the disappearance of electromagnetic energy difflised into the highly
20 conductive medium 33.
Thus, there is an effect that the first power-transmitting-side containment member 312 and the first power-receiving-side containment member 322 reduce dielectric loss in the vicinity of the power transmission coil 311 and the power reception coil 321.
25 [0054]

27 Further, because the tiiird powcr-transmitting-side containment member 314 and
the third power-receiving-side containment member 324 are provided in the electric
power transmission device 3 according to the third embodiment, it is possible to use a
liquid (for example, pure water or distilled water) having the same specific gravity as the
5 highly conductive medium 33 (seawater) and having low conductivit)' in the second
power-transiuitting-side containment member 313 and the second power-receiving-side
containment member 323. Therefore, the power transmitting unit 31 and the power
receiving unit 32 can use the second povver-transmitting-side containment member 313
and the second power-receiving-side containment member 323 for neutral buoyancy.
10 [0055]
As shown above, the electric power transmission device 3 according to the third
embodiment can be implemented at a low cost as in the electric power transmission
device 1 according to the first embodiment and the electric power transmission device 2
according to the second embodiment because it is unnecessary to provide a separate
15 specific gravit)' adjustment mechanism.
[Example 1]
[0056]
Next, the first example in the third embodiment is illustrated in FIG. 11.
In FIG II, the power transmitting unit II of the electric power transmission
20 device 1 is provided in an electric power supply source 14 and the power receiving unit
12 is provided in a submarine 15. Even when the tide moves and a positional
relationship between the electric power supply source 14 and the submarine 15 fluctuates,
it is possible to stably supply electric power using the present invention.
[Example 2]
25 [0057]

28 Tn addition, the second example in the third embodiment is iiiiistrated in FIG. 12.
In FIG 12, the power transmitting unit! 1 of the electric power transmission
device 1 is provided in a submarine 16 and the power receiving unit 12 is provided in a
submarine 17. Even when the tide moves and a positional relationship between the
5 submarine 16 and the submarine 17 fluctuates, it is possible to stably supply electric
power using the present invention.
[0058]
In addition, the submarines 16 and 17 can bi-directionally supply electric power
using the power transmitting unit 11 as a power receiving unit and using the power
10 receiving unit 12 as a power transmitting unit. Alternatively, the submarines 16 and 17
may be provided with both the power transmitting unit 11 and the power receiving unit
12.
Also, the submarine 17 including the power receiving unit 12 may be a sensor
device or the like placed in a ship or under the sea.
15 [Example 3]
[0059]
Next, the third example in the third embodiment is illustrated in FIG. 13.
The power transmitting unit 11 is provided in a comiection member of a power
cable 18 and the power receiving unit 12 is provided in a connection member of a power
20 cable 19. Using the present iiwention, even in seawater, by wirelessly supplying
electric power, a contactless t)'pe of connection between the cables can be established,
the replacement of the power cable is facilitated, and reliability is also improved without
abrasion.
[0060]
25 In addition, the power cable 18 and the power cable 19 can bi-directionally

29 supply electric power using the power transmitting unit 11 as the power receiving unit
and using the power receiving unit 12 as the power transmitting unit. Further, the
above-described power cable 18 and the above-described power cable 19 may be
provided with both the power transmitting unit 11 and the power receiving unit 12.
5 [0061]
In addition, a function of wirelessly transmitting information to the power
transmitting unit 11 and the power receiving unit 12 may be installed. Because it is
unnecessary' to separately provide a wireless communication mechanism using the power
transmitting unit U as a transmitter and using the power receiving unit 12 as a receiver, it
10 is possible to implement the system at a low cost in a small size.
[Example 4]
[0062]
FIG. 14 is a model diagram for simulations for verifying the effect of an electric
power transmission device 4 according to the third embodiment.
15 As the first example of the third embodiment of the present invention, a specific
simulation model verifying its effect will be described with reference to FIG. 14.
In FIG. 14, the electric power transmission device 4 includes a power
transmitting unit 41 and a power receiving unit 42. In addition, the power transmitting
unit 41 and the power receiving unit 42 arc covered with the highly conductive medium,
20 seawater 43. The above-described power transmitting unit 41 includes a helical coil
(power transmission coil) 411, an internal dielectric (first power-transmitting-side
containment member) 412, an external dielectric (second power-transmitting-side
containment member) 413, and a covering dielectric (third power-transmitting-side
containment member) 414. The above-described power receiving unit 42 includes a
25 helical coil (power reception coil) 421, an internal dielectric (first power-receiving-side

30 containment member) 422, an external dielectric (second power-receiving-side
containment member) 423, and a covering dielectric (third power-receiving-side
containment member) 424.
[0063]
5 FIG. 15 is a schematic top view oftlie power transmitting unit 41 in the first
example of the third embodiment.
The helical coil 411 illustrated in FIG. 15 has a structure in which t^vo
single-layer coils, each of which is formed by winding a conducting wire having a
diameter of 2 mm 29 times in an outer diameter of 220 mm and an inner diameter of 100
10 mm, are separated by a distance of 3 mm and face each other.
AC power is applied fi'om a power feeding port to these opposing helical coils. The internal dielectric 412 is formed of a fluorine resin and the covering dielectric 414 is formed of an acryl. Sizes of the covering dielectric 414 are a length of 255 mm, a width of 255 mm, and a height of 19 mm. Aresonance frequency oftlie above-described
15 electric power transmission device 4 is 1 MHz. Here, in this example, even when a
ratio dl/d2 between the size d2 of the outer diameter of the helical coil and the size dl of the covering dielectric is 1.16, which is greater than 1, sufficiently high electric power transmission efficiency is obtained. However, if the ratio of dl/d2 is greater than 1.16, higher electric power transmission efficiency is obtained.
20 The power receiving unit 42 has the same configuration as the power
transmitting unit 41._ However, the configuration shown here is an example and similar effects are obtained even when the power transmitting unit 41 and the power receiving unit 42 do not have the same configuration. [0064]
25 FIG. 16 is a graph illustrating simulation results of electric power transmission

31 efficiency in the first example of the third embodiment.
By setting a distance d between the power transmitting unit 41 and the power
receiving unit 42 to 10 cm and simulating electric power transmission efficiency in
seawater, it was possible to obtain high electric power transmission efficiency of 40% or
5 more when a frequency f of electric power to be transmitted is in the vicinity' of 1 MHz
as illustrated in FIG. 16.
[0065]
Figs. 17A and I7B are views illustrating electric field vectors in the vicinity of
the power transmitting unit 41 and the power receiving unit 42 in the first example of the
10 third embodiment, and Figs. ISAand 18B are views illustrating magnetic field vectors in the vicinity of the power transmitting unit 41 and the power receiving unit 42 in the first example of the third embodiment. Figs. 19Aand 19B are views illustrating Poynting vectors in the vicinity of the power transmitting unit 41 and the power receiving unit 42 in this embodiment.
15 Results obtained by performing detailed three-dimensional electromagnetic field
simulations in terms of an electric field, a magnetic field, and a Poynting vector in the electric power transmission device 4 according to the above-described example will be described with reference to Figs. 17Ato 19B.
In the first example of the third embodiment, the flow of the electric field rotates
20 along a surface parallel to a coil surface as illustrated in Figs. 17A and 17B, and the flow of the magnetic field is radially generated along the surface parallel to the coil surface as illustrated in Figs. 18A and 188. Based on the flows of the electric field and the magnetic field, a Poynting vector (energy flow) substantially perpendicular to the coil surface is generated (Figs. I9A and I9B). As a result, even in seawater in which a
25 distance between flie power transmitting unit 41 and the power receiving unit 42 is

32 separated about 10 cm, the energy flow is formed in a direction substantially
perpendicular to the coil surface and the long-distance transmission in the seawater is
possible.
[0066]
5 Figs. 20Aand 20B are views illustrating Poynting vectors of the electric power
transmission device 4 according to the first example of the third embodiment in the air. Results obtained by simulating the power transmitting unit 41 and the power
receiving unit 42 of the electric power transmission device 4 according to tiiis
embodiment separated by a distance of 10 cm will be described with reference to Figs. 10 20Aand20B.
As illustrated in Figs. 20A and 20B, the energy flow perpendicular to the surface
of the power transmitting/receiving unit does not occur and the energy has a flow that
forms a spiral. That is, a phenomenon in which a flow of energy substantially
peqDendicular to the coil surface occurs is a phenomenon unique to energy that is 15 propagated in the highly conductive medium and is a phenomenon that does not occur
when the energy is propagated in the air. That is, the present invention uses a unique
phenomenon in which the flow of energy substantially perpendicular to the coil surface
occurs.
[0067]
20 Figs. 2IA and 21B arc views illustrating Poynting vectors in the air when
conventional magnetic field resonance technolog)' is used.
Next, results obtained by performing simulations in the air using the
conventional electromagnetic resonance technology will be described with reference to
Figs. 21A and 21B.
25 As illustrated in Figs. 21A and 21B, even in tiiis case, the energy flow

33 perpendicular to the surface of tlie power transmitting/receiving unit does not occur and
the energy has a flow that forms a spiral as in Figs. 20A and 20B. hi this case, the
electric power transmission efficiency is 90%. Also, as described already, high electric
power transmission efficiency is not obtained even when wireless electric power
5 transmission is attempted in seawater using an electric power transmission device
according to the conventional technology. From simulation results, it could be seen that
only an electric power transmission efficiency of about 10% at a distance of 10 cm is
obtained.
[0068]
10 Figs. 18A and 18B illustrate slates of magnetic fields under a phase condition in
which interlinkage magnetic fluxes passing through the helical coil 411 and the helical
coil 421 of the power transmitting unit 41 and the power receiving unit 42 are
maximized.
Physical differences between the conventional electromagnetic resonance
15 technology and the electric power transmission device 4 according to the first example of
the third embodiment will be described with reference to Figs. 18A and 18B.
As illustrated in Figs. 18A and I8B, the interlinkage magnetic flux passing
through the helical coil 411 of the power transmitting unit 41 and the interlinkage
magnetic flux passing through the helical coil 421 of the power receiving unit 42 are
20 directed in directions reverse to each other, so that tiie magnetic field is maximized and
the magnetic field parallel to the coil surface is generated.
On the other hand, in the wireless electric power transmission technology using
electromagnetic resonance, a resonance frequency is divided into t\vo parts in the case of
close coupling and it is generally known that interlinkage magnetic fluxes passing
25 througii the coils of the power transmitting unit and the power receiving unit are in

34 atiti-phase at a higher resonance frequency. In addition, in tlie same technoiog}', in a
state of ioosc coupling in which the resonance trequency is not divided, it is generally
known that the interlinkage magnetic fluxes passing through the coils of the power
transmitting unit and the power receiving unit are in phase.
5 The present invention is fiindamentally difterent from the conventional
electromagnetic resonance technology in that the interlinkage magnetic fluxes passing
through antenna coils of the power transniitting unit and the power receiving unit are in
anti-phase in a state of loose coupling in which the resonance frequency is not divided
rather than the close coupling state.
10 [Example 5]
[0069]
FIG. 22 is a model diagram for simulations for verifying the effect of an electric power transmission device 5 according to the third embodiment.
Next, simulation results obtained by verifying the effect of the second example
15 in the third embodiment of the present invention will be described with reference to FIG. 22.
In FIG. 22, the electric power transmission device 5 includes a power transmitting unit 51 and a power receiving unit 52. In addition, the power transmitting unit 51 and the power receiving unit 52 are covered with the highly conductive medium,
20 scawater 53. The above-described power transmitting unit 51 includes a spiral coil 5111, a loop coil 5112, an internal dielectric (first power-transmitting-side containment member) 512, an extenial dielectric (second power-transmitting-side containment member) 513, and a covering dielectric (third power-transmitting-side containment member) 514. The above-described power receiving unit 52 includes a spiral coil 5211,
25 a loop coil 5212, an internal dielectric (first power-rcceiving-side containment member)

35 522, ail externai dielectric (second power-receiving-side containment member) 523, and
a covering dielectric (third power-receiving-side containment member) 524.
[0070]
Figs. 23 and 24 are model diagrams of the spiral coil 5111 (spiral coil 5211)
5 viewed from the top surface and the side surface in the second example of the third
embodiment, respectively.
The spiral coil 5111 includes a dielectric substrate 5113 formed of a fluorine
resin and a spiral wiring 5114 formed of a metal wiring. The dielectric substrate 5113 is
configured to have a thickness of 1 mm, a length of 270 mm, and a width of 270 mm.
10 The spiral wiring 5114 is configured to have a length of 260 mm, a width of 260 mm, a
wiring width of 6 mm, a thickness of 50 \xm, and 10 turns.
[0071]
Figs. 25 and 26 are model diagrams of the loop coil 5112 (loop coil 5212)
viewed from the top surface and the side surface in the second example of the third
15 embodiment, respectively.
The loop coil 5112 includes a dielectric substrate 5115 formed of a fluorine resin
and a loop wiring 5116 formed of a metal wiring. The dielectric substrate 5115 is
configured to have a thickness of 1 mm, a length of 270 mm, and a width of 270 mm.
The loop wiring 5116 is configured to have a length of 260 mm, a width of 260 mm, a
20 wiring width of 6 mm, and a thickness of 50 jam.
[0072]
A distance of 3 mm between the spiral coil 5111 and the loop coil 5112 within
the internal dielectric 512 is separated. A high electric power transmission efficiency of
55% or more was obtained by simulating the above-described power transmitting unit 51
25 and the above-described power receiving unit 52 separated by a distance of 10 cm in

36 seawater. Also, tlie resonance frequency is about 1 MHz.
In this example, the power receiving unit 52 has the same configuration as the
power transmitting unit 51. However, the configuration sliown here is an example and a
similar effect is obtained even when the power transmitting unit 51 and the power
5 receiving unit 52 do not have the same configuration.
[0073]
As in the second example of the third embodiment, mass productivity is
increased by forming a coil on a dielectric substrate, manufacturing precision is high,
characteristic variation for each individual can be reduced. Thus, it is possible to make
10 the resonance frequencies of the power transmitting unit and the power receiving unit
equal and obtain higher electric power transmission efficiency.
[Example 6]
[0074]
FIG. 28 is a model diagram for simulations for verifying the effect of an electric
15 power transmission device 6 according to the third embodiment of the present invention.
Next, as the third example of the third embodiment of the present invention, a
specific simulation result verifying its effect will be described with reference to FIG. 28.
In FIG. 28, the electric power transmission device 6 includes a power
transmitting unit 61 and a power receiving unit 62. In addition, the power transmitting
20 unit 61 and the power receiving unit 62 are covered with seawater 63. The power
transmitting unit 61 includes a power transmission coil constituted of a spiral coil 6111
and a spiral coil 6112, a first power-transmitting-side containment member 612
constituted of a first dielectric configured to cover the power transmission coil, a second
power-transmitting-side containment member 613 constituted of a second dielectric
25 configured to cover the first power-transmitting-side containment member 612, a third

37 power-transmitting-side containment member 614 constituted of a third dielectric
configured to cover the second power-transmitting-side containment member 613. In
addition, like the power transmitting unit 61, the power receiving unit 62 includes a
power reception coil constituted of a spiral coil 6211 and a spiral coil 6212, a first
5 power-recciving-side containment member 622, a second power-receiving-side
containment member 623, and a third power-receiving-side containment member 624.
[0075]
Here, the simulation model in the third example of the third embodiment has a
structure in which the second power-transmitting-side containment member 613 (second
10 power-receiving-side coirtainment member 623) covers only an upper surface and a
lower surface (a surface parallel to a coil surface) of the first power-transmitting-side
containment member 612 (first power-receiving-side containment member 622) as
illustrated in FIG. 28. That is, the first power-transmitting-side containment member
612 (first power-receiving-side containment member 622) is inserted into the second
15 power-transmitting-side containment member 613 (second power-receiving-side
containment member 623). On the other hand, a side surface (a surface perpendicular to
the coil surface) of the first power-transmitting-side containment member 612 (first
power-receiving-side containment member 622) has a structure directly covered with the
third power-transmitting-side containment member 614 (third power-receiving-side
20 containment member 624).
[0076]
FIG. 29 is a model diagram of the power transmitting unit 61 viewed from the
side surface in the third example of the third embodiment.
The first power-transmitting-side containment member 612 is formed of two
25 fluorine resins, each of which has a length of 250 mm, a width of 250 mm, and a height

38 of 4.5 mm. The specific dieiectric constant is 10.2 and the dielectric tangent is 0.0023.
In addition, the second powei-transmitting-side containment member 613 is
fonned of two fluorine resins, each of which has a length of 250 mm, a width of 250 mm,
and a height of 6 mm. The specific dielectric constant is 6.2 and the dielectric tangent
5 is 0.0019.
In addition, the third power-transmitting-side containment member 614 is
formed of acryi having a length of 260 mm, a width of 260 mm, a height of 26.5 mm,
and a thickness of 5 mm. The specific dielectric constant of acrj'l is 3.3 and the
dielectric tangent thereof is 0.04.
10 Also, in the third example of the third embodiment, the power receiving unit 62
was also simulated in the same configuration as that of the above-described power
transmitting unit 61.
[0077J
Figs. 30 and 31 are model views of spiral coils 6111 and 6112 of the power
15 transmitting unit 61 in the third example of the third embodiment viewed from the power
receiving unit side, respectively.
The spiral coil 6111 is constituted of a wiring fonned of a 50-tum conductor
having an outer peripheiy of 208 mm. Adiameter of the wiring is 1 mm and an interval
of the wiring is 1 mm. The spiral coil 6112 has the same size as the spiral coil 6111.
20 The spiral coil 6111 and the spiral coil 6112 are disposed to be separated by a distance of
0.5 mm. An end portion of the outermost periphciy of the spiral coil 6111 and an end
portion of the outermost periphery of the spiral coil 6112 serve as power feeding ports of
high-frequency electric power. The direction of the spiral of the spiral coil 6111 and the
direction of the spiral of the spiral coil 6112 are configured to be directions in which the
25 magnetic field is generated in the same direction via the power feeding ports.

39 [0078]
Figs. 32 and 33 are model views of spiral coils 6211 and 6212 of the power
receiving unit 62 in the third example of the third embodiment viewed from the power
transmitting unit side, respectively.
5 A spiral coil 6211 is constituted of a wiring formed of a 50-turn conductor
having an outer peripheiy of 208 mm. A diameter of the wiring is 1 mm and an interval
of the wiring is 1 mm. The spiral coil 6212 has the same size as the spiral coil 6211.
The spiral coil 6211 and the spiral coil 6212 are disposed to be separated by a distance of
0.5 mm. An end portion of the outermost periphery of the spiral coi! 6211 and an end
10 portion of the outermost peripher>' of the spiral coil 6212 serve as power receiving ports of high-frequency power. The direction of the spiral of the spiral coi! 6211 and the direction of the spiral of the spiral coil 6212 are configured to be directions in which the magnetic field is generated in the same direction via the power receiving ports. [0079]
15 A high electric power transmission efficiency of 72% or more was obtained by
simulating the above-described power transmitting unit 61 and the above-described power receiving unit 62 separated by a distance of 10 cm in seawater as illustrated in FIG. 34. Also, the resonance frequency is about 140 MHz.
In the third example of the third embodiment, the power receiving unit 62 has
20 the same configuration as the power transmitting unit 61. However, the configuration shown here is an example and a similar effect is obtained even when the power transmitting unit 61 and the power receiving unit 62 do not have the same configuration. [0080]
By configuring a pluralit}' of dielectrics to cover a coil as indicated by
25 simulations according to the third example of the third embodiment, high-frequency

40 waves can be obtained witliout increasing loss within tlie dielectric and high electric
power transmission efficiency is obtained.
[0081]
Priority is claimed on Japanese Patent Application No. 2012-191649, filed
5 August 31, 2012, the content of which is incorporated herein by reference.
INDUSTRIAL APPLICABILITY [0082]
An electric power transmission device capable of increasing a distance of 10 wireless electric power transmissions in a highly conductive medium such as seawater can be provided.
[Description of Reference Symbols] [0083]
1 Electric power transmission device
15 11 Power transmitting unit
111 Power transmission coil
112 Power-transmitting-side containment member
113 Power-transmitting-side impedance adjustment unit
12 Power receiving unit
20 121 Power reception coil
122 Power-receiving-side containment member
123 Power-receiving-side impedance adjustment unit

13 Highly conductive medium
14 Electric power supply source 25 15 Submarine

41
16 Submarine
17 Submarine
18 Power cable
19 Power cable
5 2 Electric power transmission device
21 Power transmitting unit
211 Power transmission coil
212 First power-transmitting-side containment member
213 Second power-transmitting-side containment member 10 22 Power receiving unit ^

221 Power reception coil
222 First power-receiving-side containment member
223 Second power-receiving-side containment member 23 Highly conductive medium
15 3 Electric power transmission device
31 Power transmitting unit
311 Power transmission coil
312 First power-transmitting-side containment member
313 Second power-transmitting-side containment member 20 314 Third power-transmitting-side containment member
32 Power receiving unit
321 Power reception coil
322 First power-receiving-side containment member
323 Second power-receiving-side containment member 25 324 Third power-receiving-side containment member

42 33 Highly conductive medium
4 Electric power transmission device
41 Power transmitting unit
411 Helical coil
5 421 Helical coil
412 Internal dielectric
422 Internal dielectric
413 External dielectric
423 External dielectric
10 414 Covering dielectric
424 Covering dielectric
42 Power receiving unit
43 Seawater
5 Electric power transmission device
15 51 Power transmitting unit
51 !1 Spiral coil
5211 Spiral coii 5112 Loop coil
5212 Loop coil
20 5113 Dielectric substrate
5114 Spiral wiring
5115 Dielectric substrate
5116 Loop wiring 512 Internal dielectric
25 522 Internal dielectric

513 External dielectric
523 External dielectric
514 Covering dielectric
524 Covering dielectric
52 Power receiving unit
53 Seawater
6 Electric power transmission device
61 Power transmitting unit
6111 Spiral coil
6112 Spiral coil
6211 Spiral coil
6212 Spiral coil

612 First power-transmitting-sidc containment member
613 Second power-transmitting-side containment member 614 Third power-transmitting-side contaiiunent member
62 Power receiving unit
622 First power-receiving-side containment member
623 Second power-receiving-side containment member
624 Third power-receiving-side containment member 20 63 Seawater

WE CLAIMS:-
i. An electric power transmission device for wirelessly transmitting electric power in a highly conductive medium, the electric power transmission device 5 comprising:
a power transmitting unit configured to wiretessly 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
10 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 15 impedance of the highly conductive medium.
2. The electric power transmission device according to claim I, wherein a capacitance component (CI [pF]) constituting the impedance of the power transmitting unit, a capacitance component (C2 [pF]) constituting the impedance of the power
20 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]) bet\veen the power transmitting unit and the power receiving unit satisfy a relationship of 30>C3-d/(Cl+C2)>0.5.
25

45 3. The eiectric power transmission device according to claim 1 or 2, wherein at
least one of the power transmitting unit and the power receiving unit includes
an impedance adjustment unit configured to varj' seif-impedance.
5 4. The electric power transmission device according to any one of claims 1 to
3, wherein a magnitude (dl [cm]) of a direction along an electric power transmission coil
surface of the containnient member and an outer diameter (d2 [cm]) of the electric power
transmission coil satisfy a relationship of dl/d2>1.2.
10 5. The electric power transmission device according to any one of claims I to
4, wherein the containment member includes
a fust 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 15 the first containment member.
6. The electric power transmission device according to claim 5, wherein the
containment member further inchides
a covering unit having a third dielectric configured to cover the second 20 containment member.
7. The electric power transmission device according to claim 5 or 6, wherein
the second dielectric is constituted of a dielectric having the same specific gravit)' as the
highly conductive medium.
25

46 8. The electric power transmission device according to any one of claims 5 to
7, wherein a dielectric tangent of the first dielectric is less than or equal to a dielectric
tangent of the second dielectric.
5 9. The electric power transmission device according to any one of claims 5 to
8, 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 any one of claims 1 to
10 9, wherein the highly conductive medium has conductivity greater than 1x10^'' and a
specific dielectric constant greater than 1.
11. The electric power transmission device according to any one of claims 1 to
10, wherein the highly conductive medium is any one of seawater, a river, fresh water,
15 tap water, soil, and concrete.
12. The electric power transmission device according to any one of claims 1 to
11,
wherein part or all of an electric field occurring in the highly conductive 20 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 higlily conductive medium is directed approximately in parallel to the electric power transmission coil surface of the power transmitting unit or the power receiving unit. 25

47
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 5 each other in a phase condition in which the magnetic field is maxhnized, thereby generating t!ie magnetic field parallel to the electric power transmission coil surface.
14. The electric power transmission device according to any one of claims 1 to
13,
10 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 ixom the power transmitting unit to the 15 power receiving unit is wirelessly performed.
15. The electric power transmission device according to any one of claims 1 to
14, wherein electric power transmission is wirelessly performed from the power
transmitting unit to the power receiving unit using the power transmitting unit and the
20 power receiving unit in connection members of power cables placed in seawater.
16. The electric power transmission device according to any one of claims 1 to
15, wherein electric power transmission and wireless communication are simultaneously
performed using the power transmitting unit as a transmitter for transmitting information
25 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:
5 covering, by a contaiimient 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
10 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 higlily conductive medium.