JP2009188131A - Non-contact power transmission device - Google Patents

Abstract

An object of the present invention is to provide a non-contact power transmission device capable of reducing the interaction between a primary coil and a secondary coil (reducing the magnetic coupling coefficient) and realizing stable power transmission in a wider range.
Electric power is transmitted in a non-contact manner from a primary coil to a secondary coil using electromagnetic induction. The primary coil and the secondary coil are both planar spiral coils and are opposed to each other in the axial direction. The outer diameter of the secondary coil is smaller than the outer diameter of the primary coil. The magnetic coupling coefficient between the primary side coil and the secondary side coil is 0.1 to 0.8.
[Selection] Figure 1

Description

  The present invention relates to a non-contact power transmission device that transmits power in a non-contact manner, and more particularly to a non-contact power transmission device used in a portable electronic device, a portable electric device, an electronic device, or the like.

  2. Description of the Related Art In recent years, a system that uses an electromagnetic induction effect between opposed coils has been proposed as one of methods for transmitting power from a power source to an electronic device without contact. As such a system, for example, there is a system called a cordless power station or a contactless power station, which is generally abbreviated as CLPS.

  Non-patent documents 1 and 2 describe the configuration of the power transmission side excitation air of such a non-contact power transmission system.

  Non-Patent Document 1 discusses the advantages and disadvantages of different construction methods, the improvement of characteristics by inserting capacitors, the effect of ferrite on the improvement of transmission power and transmission efficiency, and the improvement of transmission characteristics by displacement of the primary and secondary sides. It is what went. Specifically, in the non-contact power transmission apparatus, a connection method is used in which donut-shaped air core coils are arranged on both the primary side and the secondary side, and the directions of magnetic fluxes of adjacent coils are reversed. The reason for this is that the connection method in which the directions of the magnetic fluxes of adjacent coils are opposite to each other intensifies the magnetic flux and the leakage magnetic flux to the outside is greater than the connection method in which the generated magnetic fluxes are all in the same direction. This is because it has the advantage of being less.

In Non-Patent Document 1, when the number of air-core coils is increased on both the primary side and the secondary side, the maximum transmission power P2 _max and the maximum transmission efficiency η _max both increase and a disc-shaped ferrite core is used. In this case, it is disclosed that transmission power can be increased and transmission efficiency can be improved.

  Furthermore, in Non-Patent Document 1, when a capacitor having a capacity obtained from the resonance condition of the secondary coil and the self-inductance of the secondary coil is inserted in series between the secondary coil and the load resistance, the loss is reduced and the transmission efficiency is reduced to about It is stated that it will improve by 10%.

  In Non-Patent Document 1, the amount of power loss and transmission efficiency do not depend on the thickness of the ferrite core and do not depend on the type of ferrite. Has been shown to be advantageous. Further, in Non-Patent Document 1, it has been found that in the case of a coil shape that uses only a magnetic flux component perpendicular to the surface, it is better to match the central axes.

  However, in the non-contact power transmission device disclosed in Non-Patent Document 1, since the primary side and secondary side coils have the same dimensions, there is a large change due to misalignment, and in a wide range of aspects. It has the disadvantage of being inconvenient for any transmission.

In the non-contact power transmission system disclosed in Non-Patent Document 2, one spiral coil is disposed on the power reception side, and a plurality of parallel spiral coils are disposed on the power transmission side, opposite to the opposing surface of each spiral coil. It is the structure which has arrange | positioned the magnetic body thin plate or sheet | seat on the side, respectively. According to the non-contact power transmission system according to Non-Patent Document 2 having such a configuration, when the inner diameter / outer diameter ratio (D _i / D ₀ ) is 0.65 on the power receiving side, the maximum transmission power is about 70 W, and the inter-coil efficiency is about 65% is obtained. Further, the magnetic coupling coefficient k is greatly involved in the transmission characteristics, and D _i / D ₀ = 0.65 is the mutual inductance Mc between the power transmission coil and the power reception coil located in the center and the power transmission coil located outside. It is shown that the transmission characteristics are improved in that it is substantially equal to the mutual inductance M0 with the power receiving coil.

  Further, in Non-Patent Document 2, the non-contact power transmission device uses electromagnetic induction between the opposed primary side and secondary side coils, and is not connected from the primary side coil 1 to the secondary side coil 2 via a gap. Power is transmitted by contact.

  In such a non-contact power transmission device of Non-Patent Document 2, when the capacitor C2 is inserted in parallel with the load so as to cancel the inductive reactance of the coil in parallel to the power receiving coil side, improvement in efficiency can be seen. And it is shown that the fluctuation range of transmission efficiency can be improved by making the shape of the magnetic body on the back side of the power receiving coil into a shape that further prevents leakage.

  However, in the non-contact power transmission device disclosed in Non-Patent Document 2, the primary side coils are arranged in a plane, and there is a dead point that cannot be transmitted in the plane of transmission by adjacent coils. Therefore, the secondary side coil needs to be larger than the primary side coil. Therefore, the configuration is inconvenient for downsizing of the secondary side.

  Further, Patent Document 1 is the same as Non-Patent Document 1, and the primary side and secondary side coil configurations are the same, and stable transmission becomes difficult due to the coil position deviation.

  In Patent Document 2, a soft magnetic member made of soft magnetic powder and an organic binder is disposed on the outer side of the opposing primary coil and secondary coil, and stable due to misalignment between planar spiral coils. Did not mention the transmission. A combination of a planar spiral coil and a meander coil is shown as a configuration that widens the allowable range of positional deviation.

JP-A-7-231586 JP-A-8-148360 Junichi Murakami, Hidetoshi Matsuki, Shinki Kikuchi: “Non-contact power transmission characteristics by cordless power station using ferrite”, IEICE Technical Report, Magnetics Study Group, MAG-93-138, pp. 63-70, 1993 August 2 Published by The Institute of Electrical Engineers of Japan Junichi Hatanaka, Fumihiro Sato, Hidetoshi Matsuki, Shinki Kikuchi, Junichi Murakami, Makoto Kawase, Tadakuni Sato: “Study on the power transmission side excitation configuration of non-positioning non-contact power transmission system”, Journal of Japan Society of Applied Magnetics, Vol. 26, Vol. 580-584 (2002)

  Therefore, the non-contact power transmission systems disclosed in Non-Patent Documents 1 and 2 and Patent Documents 1 and 2 need to be further improved so that high output and stable power transmission can be performed in a wide range.

  Then, the subject of this invention is providing the non-contact electric power transmission apparatus which can implement | achieve the stable electric power transmission in a wide range.

  Another object of the present invention is to provide a non-contact power transmission apparatus that improves output by improving convergence of magnetic flux.

  According to an aspect of the present invention, in the power transmission device that transmits electric power from the primary coil to the secondary coil in a non-contact manner using electromagnetic induction, the primary coil and the secondary coil are planar spirals. A secondary coil having an outer diameter smaller than an outer diameter of the primary coil, and a magnetic coupling coefficient between the primary coil and the secondary coil. Is 0.1 to 0.8, a non-contact power transmission device is obtained.

  In this non-contact power transmission apparatus, the ratio of the outer diameter of the secondary coil to the outer diameter of the primary coil (the outer diameter of the secondary coil / the outer diameter of the primary coil) is 0.85 or less. It may be.

  In these non-contact power transmission devices, the ratio of the inner diameter of the secondary coil to the inner diameter of the primary coil (the inner diameter of the secondary coil / the inner diameter of the primary coil) is 0.85 or less. Also good.

  In these non-contact power transmission devices, a gap between the secondary coil and the primary coil may be 10 mm or less.

  In these non-contact power transmission devices, a soft magnetic material may be disposed outside at least one of the secondary side coil and the primary side coil.

  According to another aspect of the present invention, in the power transmission method for transmitting electric power from the primary coil to the secondary coil in a non-contact manner using electromagnetic induction, the primary coil and the secondary coil are planar. It becomes a spiral coil and is opposed to each other in the axial direction, the outer diameter of the secondary coil is made smaller than the outer diameter of the primary coil, and between the primary coil and the secondary coil A non-contact power transmission method characterized by including a magnetic coupling coefficient of 0.1 to 0.8 is obtained.

  According to still another aspect of the present invention, in a power feeding side device that feeds power in a contactless manner using electromagnetic induction to a power receiving side device having a secondary side coil composed of a planar spiral coil, the secondary side coil A primary coil composed of a planar spiral coil that can be opposed in the axial direction, the primary coil having an outer diameter larger than the outer diameter of the secondary coil, and a magnetic force with respect to the secondary coil; A power feeding side device having a coupling coefficient of 0.1 to 0.8 is obtained.

  In the power feeding device, the outer diameter of the primary coil may be equal to or greater than 0.85 of the outer diameter of the secondary coil.

  In these power supply side devices, the inner diameter of the primary coil may be equal to or greater than 0.85 of the inner diameter of the secondary coil.

  In these power supply side devices, a soft magnetic material may be provided outside the primary side coil.

  The non-contact power transmission apparatus and the non-contact power transmission method described above enable realization of stable power transmission in a wide range.

  Further, the power supply side device described above can stably supply power in a wide range to the power reception side device provided with the secondary side coil composed of a planar spiral coil.

  Furthermore, when a soft magnetic material is disposed outside at least one of the secondary coil and the primary coil, high output power transmission is possible.

  The non-contact power transmission apparatus according to the embodiment of the present invention uses electromagnetic induction between opposing coils to transmit power from the primary coil to the secondary coil in a non-contact manner via a gap. In this case, the primary side coil functions as a part of the power feeding side device, and the secondary side coil 2 functions as a part of the power receiving side device.

  In this non-contact power transmission device, the primary side coil and the secondary side coil are constituted by a pair of planar coils having planar spiral coils. These planar coils are arranged so as to face each other in the axial direction. The planar coil is not limited to a circular shape as long as it is a planar type, but may be a polygonal shape, but is preferably a planar winding coil.

  The outer diameter of the secondary coil is smaller than the outer diameter of the primary coil, and the magnetic coupling coefficient between these coils is set to 0.1 to 0.8, thereby suppressing fluctuations in output due to misalignment between the coils. Stable power transmission over a wide range can be realized.

  In the non-contact power transmission device, the ratio of the opposing secondary coil outer diameter to the primary coil outer diameter (secondary coil outer diameter / primary coil outer diameter) should be 0.85 or less. As a result, fluctuations in output due to positional deviation between coils can be suppressed, and stable power transmission in a wide range can be realized.

  In any one of the non-contact power transmission devices, the ratio of the opposing secondary coil inner diameter to the primary coil inner diameter (secondary coil inner diameter / primary coil inner diameter) is 0.85 or less. As a result, fluctuations in output due to positional deviation between coils can be suppressed, and stable power transmission in a wide range can be realized.

  Furthermore, in any one of the non-contact power transmission devices, the gap between the opposing secondary side coil and the primary side coil is set to 10 mm or less, so that fluctuations in output due to misalignment between the coils are suppressed, and a wide range is achieved. Can realize stable power transmission. Here, the reason why the coil gap is set to 10 mm or less is that if it exceeds 10 mm, the output power becomes small and becomes impractical.

  Further, by arranging a soft magnetic material on the outer side of either one or both of the opposing secondary side planar coil and primary side planar coil, the primary side coils 1 and 2 are caused by the convergence effect of the generated magnetic field. The magnetic coupling of the secondary coil can be improved and the output can be improved.

  Further, in non-contact power transmission with a configuration similar to that of the present invention using a pair of planar coils having the same shape, the magnetic coupling coefficient k is about 0.95 to 0.98 when the center axis is aligned as the coil gap 0. In this configuration, the tolerance of the positional deviation between the primary side coil and the secondary side coil is extremely low, and the transmission power becomes almost zero when the central axis of each coil is deviated by 25% of the diameter. Incidentally, if the diameter is similarly shifted by 10%, the transmission power is halved.

  In addition, the present invention is configured so that the secondary side coil is smaller than the primary side coil so that it is useful in non-contact transmission to an electronic device or the like, particularly in application to a portable device. It is intended to reduce the weight.

  Various embodiments of the present invention will be described below with reference to the drawings.

[Example 1]
As shown in FIG. 1, the primary coil 1 and the secondary coil 2 are arranged so as to face each other in the axial direction, and the gap between these coils is 1 mm. On the outer side of the primary side coil 1 and the secondary side coil 2, soft magnetic materials 3 and 4 made of a sintered MnZn ferrite having a thickness of 0.5 mm were arranged so as to protrude from the outer side of the coil.

  The secondary coil 2 has an outer diameter of 30 mm, an inner diameter of 15 mm, and a winding number of 11. The primary coil 1 has an outer diameter of 30 to 200 mm, an inner diameter of 20 mm, and the number of turns corresponding to the outer diameter and varied in the range of 2 to 33.

  Further, as shown in FIG. 2, a power source 5 is connected to the primary coil 1, while a capacitor 6, a rectifier 7, a DC / DC converter 8, and a variable resistor 9 are connected to the secondary coil 2. The measurement circuit (LCR meter) was configured. Then, the power source 5 was set to a frequency of 120 kHz and a constant current of 50 mA, the inductance was measured with an LCR meter, and the magnetic coupling coefficient k was obtained.

  Also, the secondary coil 2 is translated from a state where the center positions of the primary coil 1 and the secondary coil 2 are aligned, and the rate of change in the magnetic coupling coefficient between the coils is 20% or less. Was determined as the k0.8 attenuation region. The relationship between the ratio of the outer diameter of the secondary coil 2 and the outer diameter of the primary coil 1 (the outer diameter of the secondary coil / the outer diameter of the primary coil) and the k0.8 attenuation region Asked. The result is shown in FIG.

  In FIG. 3, in the region where the ratio of the outer diameter of the secondary coil to the outer diameter of the primary coil is 0.85 or less, the k0.8 attenuation region is clearly increased. Therefore, stable power transmission is possible in a wider range than when the primary coil and the secondary coil having the same outer diameter are used. By the way, if this is compared in terms of area, the expansion will be about 3 times or more.

[Example 2]
As shown in FIG. 1, the primary coil 1 and the secondary coil 2 are arranged so as to face each other in the axial direction, and the gap between these coils is 1 mm. On the outer side of the primary side coil 1 and the secondary side coil 2, soft magnetic materials 3 and 4 made of a sintered MnZn ferrite having a thickness of 0.5 mm were arranged so as to protrude from the outer side of the coil.

  The secondary coil 2 has an outer diameter of 30 mm, an inner diameter of 15 mm, and a winding number of 11. The primary side coil 1 has an outer diameter of 90 mm, an inner diameter of 15 to 75 mm, and the number of turns corresponding to the outer diameter and varied in the range of 3 to 14.

  Then, the relationship between the ratio of the inner diameter of the secondary coil 2 and the inner diameter of the primary coil 1 and the k0.8 attenuation region was determined in the same manner as in Example 1. The result is shown in FIG.

  In FIG. 4, in the region where the ratio of the inner diameter of the secondary coil to the inner diameter of the primary coil is 0.85 or less, the k0.8 attenuation region is clearly increased. Therefore, stable power transmission is possible in a wider range than when using a coil having the same inner diameter. By the way, if this is compared in terms of area, the magnification is about 2.5 times or more.

[Example 3]
As shown in FIG. 1, the primary coil 1 and the secondary coil 2 are arranged so as to face each other in the axial direction, and the gap between these coils is 1 mm. On the outer side of the primary side coil 1 and the secondary side coil 2, soft magnetic materials 3 and 4 made of a sintered MnZn ferrite having a thickness of 0.5 mm were arranged so as to protrude from the outer side of the coil.

  The outer diameter ratio of the primary side coil and the secondary side coil was changed under the condition that the size of the secondary side coil 2 was smaller than that of the primary side coil 1.

  And the magnetic coupling coefficient k between coils and the k0.8 attenuation | damping area were measured with the method similar to Example 1 and 2 in the state in which the center axis | shaft of both coils is suitable. The result is shown in FIG.

  In FIG. 5, it can be seen that the range in which stable power transmission can be performed is clearly expanded by setting the magnetic coupling coefficient to 0.8 or less. Particularly, by reducing the ratio of the inner diameter of the secondary coil to the inner diameter of the primary coil, the range in which stable power transmission can be performed is significantly expanded. However, if the coupling coefficient is small, the transmittable power is small. Therefore, the magnetic coupling coefficient k of 0.1 or less is not practical.

[Example 4]
As shown in FIG. 1, the primary coil 1 and the secondary coil 2 are arranged so as to face each other in the axial direction. On the outer side of the primary side coil 1 and the secondary side coil 2, soft magnetic materials 3 and 4 made of a sintered MnZn ferrite having a thickness of 0.5 mm were arranged so as to protrude from the outer side of the coil.

  The primary coil 1 had an outer diameter of 50 mm, an inner diameter of 20 mm, and 6 windings. The secondary coil 2 had an outer diameter of 30 mm, an inner diameter of 15 mm, and a winding number of 11.

  Then, with the central axes of the primary coil 1 and the secondary coil 2 aligned, the gap between the coils is changed from 0 to 10 mm, and the magnetic coupling coefficient k is set by the same method as in the first embodiment. It was measured. The result is shown in FIG.

  In FIG. 6, the gap between the coils is 10 mm or less, the magnetic coupling coefficient k is 0.1 to 0.72, and stable power transmission can be realized in a wide range.

[Example 5]
As shown in FIG. 1, the primary coil 1 and the secondary coil 2 are arranged so as to face each other in the axial direction. The primary coil 1 had an outer diameter of 70 mm, an inner diameter of 20 mm, and 8 turns. The secondary coil 2 had an outer diameter of 30 mm, an inner diameter of 15 mm, and a winding number of 11.

  And with the central axes of the primary coil 1 and the secondary coil 2 aligned, the gap between the coils is 1 mm, and the soft magnetic material is arranged on both the primary and secondary sides. Only the secondary side was not mounted, and the magnetic coupling coefficient k was measured in the same manner as in Example 1. Again, the soft magnetic material was a 0.5 mm thick MnZn ferrite sintered body.

  The results are shown in Table 1 below.

  As is apparent from the table, by arranging the soft magnetic material, the magnetic coupling coefficient k is clearly improved, and the transmission power is improved.

[Example 6]
As shown in FIG. 1, the primary coil 1 and the secondary coil 2 are arranged so as to face each other in the axial direction. On the outer side of the primary side coil 1 and the secondary side coil 2, soft magnetic materials 3 and 4 made of a sintered MnZn ferrite having a thickness of 0.5 mm were arranged so as to protrude from the outer side of the coil.

  The primary coil 1 had an outer diameter of 50 mm, an inner diameter of 20 mm, and a winding number of 5. The secondary coil had an outer diameter of 50 mm, an inner diameter of 20 mm, and a winding number of 5.

  Then, the input frequency of the primary coil 1 was 290 kHz, the input voltage was 8.5 vrms, the gap between the coils was changed in the range of 0 to 5 mm, and the power transmission state was measured.

  As a result, an output power of about 3 W was stably obtained in a range where the in-plane position variation was about 10 mm. Incidentally, the inter-coil transmission efficiency at this time was 95%. Further, the transmission efficiency as a power source including the semiconductor element at this time was 77%.

  Compared with the case where the primary side coil 1 and the secondary side coil 2 are configured to have the same shape, the range in which power can be transmitted with a stable output has been remarkably expanded.

[Example 7]
As shown in FIG. 1, the primary coil 1 and the secondary coil 2 are arranged so as to face each other in the axial direction. On the outer side of the primary side coil 1 and the secondary side coil 2, soft magnetic materials 3 and 4 made of a sintered MnZn ferrite having a thickness of 0.5 mm were arranged so as to protrude from the outer side of the coil.

  The primary coil 1 had an outer diameter of 84 mm, an inner diameter of 40 mm, and a winding number of 8. The secondary coil 2 had an outer diameter of 50 mm, an inner diameter of 20 mm, and a winding number of 5.

  The frequency of the primary input was 232 kHz, the input voltage was 62 vrms, the gap was 1 mm, and the power transmission state was measured.

  As a result, an output power of about 3 W was stably obtained in the range where the in-plane position variation was about 50 mm. Incidentally, the inter-coil transmission efficiency at this time was 95%. Further, the transmission efficiency as a power source including the semiconductor element at this time was 77%.

  Compared with the case where the primary side coil 1 and the secondary side coil 2 are configured to have the same shape, the range in which power can be transmitted with a stable output has been remarkably expanded.

[Summary]
Various embodiments shown below can be obtained by using the above-described Examples 1 to 7.

  1. In a power transmission device that transmits electric power from a primary coil 1 to a secondary coil 2 in a non-contact manner using electromagnetic induction, the primary coil 1 and the secondary coil 2 are planar spiral coils and shafts. The outer diameter of the secondary coil 2 is smaller than the outer diameter of the primary coil 1, and the magnetic coupling coefficient between the primary coil 1 and the secondary coil 2 is 0.1-0. 8 is a non-contact power transmission device.

  2. In the non-contact power transmission device according to the first embodiment, the ratio between the outer diameter of the secondary coil 2 and the outer diameter of the primary coil 1 (the outer diameter of the secondary coil / the outer diameter of the primary coil). Is 0.85 or less, the non-contact electric power transmission apparatus characterized by the above-mentioned.

  3. In the non-contact power transmission device according to Embodiment 1 or 2, the ratio of the inner diameter of the secondary coil 2 to the inner diameter of the primary coil 1 (the inner diameter of the secondary coil / the inner diameter of the primary coil) is 0. A non-contact power transmission apparatus, characterized in that it is 85 or less.

  4). 4. The non-contact power transmission apparatus according to any one of the first to third embodiments, wherein a gap between the secondary coil 2 and the primary coil 1 is 10 mm or less.

  5). In the non-contact power transmission device according to any one of the first to fourth embodiments, the soft magnetic materials 3 and 4 are disposed outside at least one of the secondary coil 2 and the primary coil 1. Non-contact power transmission device.

  6). In a power transmission method in which electric power is transmitted from the primary side coil 1 to the secondary side coil 2 in a non-contact manner using electromagnetic induction, the primary side coil 1 and the secondary side coil 2 are formed as planar spiral coils and are used as shafts. The outer diameter of the secondary coil 2 is made smaller than the outer diameter of the primary coil 1, and the magnetic coupling coefficient between the primary coil 1 and the secondary coil 2 is 0.1. The non-contact electric power transmission method characterized by including -0.8.

  7. In a power feeding side device that feeds power in a contactless manner using electromagnetic induction to a power receiving side device comprising a secondary side coil 2 composed of a planar spiral type coil, a planar spiral type that can face the secondary side coil 2 in the axial direction. The primary side coil 1 includes a primary side coil 1, and the primary side coil 1 has an outer diameter larger than that of the secondary side coil 2, and a magnetic coupling coefficient with respect to the secondary side coil 2 is 0.1 to 0. .. 8 is a power supply side device.

  8). The power feeding side device according to the seventh embodiment, wherein the outer diameter of the primary side coil 1 is equal to or greater than 0.85 of the outer diameter of the secondary side coil 2.

  9. 9. The power supply apparatus according to Embodiment 7 or 8, wherein the inner diameter of the primary coil 1 is at least 0.85 of the inner diameter of the secondary coil 2.

  10. 10. The non-contact power transmission device according to any one of the seventh to ninth embodiments, wherein the soft magnetic material 3 is provided outside the primary coil 1.

  The non-contact power transmission device according to the present invention is applied to power transmission to portable electronic devices, portable electrical devices, and electronic devices, and is particularly suitable for portable devices.

It is a perspective view which mainly shows one example of arrangement | positioning of the coil in the non-contact electric power transmission apparatus which concerns on the Example of this invention, and arrangement | positioning of a soft magnetic material. It is a circuit diagram which shows the structural example of the measuring circuit of the non-contact electric power transmission apparatus in the Example of this invention. The secondary coil is translated from the state in which the ratio of the secondary coil outer diameter / primary coil outer diameter according to the first embodiment of the present invention matches the center position of each coil, and the magnetic coupling coefficient between the coils is reduced. It is a figure which shows the position fluctuation distance from which a rate becomes 20% or less as a k0.8 attenuation | damping area. When the secondary coil inner diameter / primary coil inner diameter ratio according to the second embodiment of the present invention and the center position of each coil are matched, the secondary coil is moved in parallel, and the reduction rate of the magnetic coupling coefficient between the coils is It is a figure which shows the position fluctuation distance used as 20% or less as a k0.8 attenuation | damping area. The magnetic coupling coefficient k between the primary coil and the secondary coil according to the third embodiment of the present invention and the secondary coil are translated from a state where the center positions of the respective coils are matched, and the magnetic coupling coefficient between the coils is reduced. It is a figure which shows the position fluctuation distance from which a rate becomes 20% or less as a k0.8 attenuation | damping area. It is a figure which shows the relationship between the gap between the primary coil and secondary coil by Example 4 of this invention, and the magnetic coupling coefficient k between a primary coil and a secondary coil.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Primary side coil 2 Secondary side coil 3, 4 Soft magnetic material 5 Power supply 6 Capacitor 7 Rectifier 8 DC / DC converter 9 Variable resistance

Claims (10)

  In the power transmission device that transmits electric power from the primary coil to the secondary coil in a non-contact manner using electromagnetic induction, the primary coil and the secondary coil are planar spiral coils and are arranged in the axial direction. The outer diameter of the secondary coil is smaller than the outer diameter of the primary coil, and the magnetic coupling coefficient between the primary coil and the secondary coil is 0.1 to 0.8. A non-contact power transmission device characterized by that.   2. The contactless power transmission device according to claim 1, wherein a ratio between an outer diameter of the secondary coil and an outer diameter of the primary coil (outer diameter of the secondary coil / outer diameter of the primary coil). Is 0.85 or less, the non-contact electric power transmission apparatus characterized by the above-mentioned.   3. The non-contact power transmission device according to claim 1, wherein the ratio of the inner diameter of the secondary coil to the inner diameter of the primary coil (the inner diameter of the secondary coil / the inner diameter of the primary coil) is 0. A non-contact power transmission apparatus, characterized in that it is 85 or less.   4. The non-contact power transmission apparatus according to claim 1, wherein a gap between the secondary side coil and the primary side coil is 10 mm or less. 5.   5. The non-contact power transmission device according to claim 1, wherein a soft magnetic material is disposed outside at least one of the secondary coil and the primary coil. Power transmission device.   In an electric power transmission method for transmitting electric power from a primary coil to a secondary coil using electromagnetic induction in a non-contact manner, the primary coil and the secondary coil are planar spiral coils in the axial direction. Opposing each other, making the outer diameter of the secondary side coil smaller than the outer diameter of the primary side coil, and setting the magnetic coupling coefficient between the primary side coil and the secondary side coil to 0.1-0. 8. A contactless power transmission method, comprising:   A planar spiral coil that can be opposed to the secondary coil in the axial direction in a power feeding side device that feeds power in a contactless manner using electromagnetic induction to a power receiving side device including a secondary coil composed of a planar spiral coil. The primary side coil has an outer diameter larger than that of the secondary side coil, and a magnetic coupling coefficient with respect to the secondary side coil is 0.1 to 0.8. A power supply side device characterized by that.   8. The power feeding side device according to claim 7, wherein an outer diameter of the primary side coil is equal to or greater than 0.85 of an outer diameter of the secondary side coil.   9. The power feeding side device according to claim 7, wherein an inner diameter of the primary side coil is not less than 0.85 of an inner diameter of the secondary side coil.   10. The non-contact power transmission device according to claim 7, wherein a soft magnetic material is provided outside the primary coil.

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