JP5923916B2 - Contactless power supply - Google Patents

Description

  The present invention relates to a non-contact power feeding device.

  Winding as a receiving coil on the main device side of a non-contact power transmission device that includes a charger having a power transmission coil and a main device having a power receiving coil, and transmits power in a non-contact manner by electromagnetic induction between the two coils. There is known a non-contact power transmission device including a planar coil in which a portion is formed in a thin planar shape, and a heat conductive layer that is in contact with all of the winding portions on at least one side of the planar coil (Patent Document 1). ).

JP 2009-4513 A

  In the conventional structure described above, a massive heat conduction layer is provided on the entire top surface of the coil. However, eddy currents are generated between the coil and the heat conduction layer provided on the entire top surface of the coil when magnetic flux flows through the coil. There is a problem that the calorific value increases.

  The problem to be solved by the present invention is to provide a non-contact power feeding device capable of suppressing heat generation of a coil.

The present invention is arranged so that the coil is disposed between the wound coils when viewed in the winding direction, and the non-magnetic length is longer than the length in the direction in which the extending direction is not straddled. By providing a metal heat conductor, the above-described problems are solved.

  According to the present invention, when a metal heat conductor that is longer than the length in the direction in which the extending direction is not straddled is provided so as to straddle between the coils, the metal heat conductor is orthogonal to the magnetic flux. Since the aspect ratio is large with respect to the direction, the generated eddy current is small. Thereby, the heat_generation | fever of a coil can be suppressed.

It is principal part sectional drawing which shows the non-contact electric power feeder which concerns on one embodiment of this invention. It is a top view which shows a coil and a metal thermal conductor among the receiving coils of FIG. It is sectional drawing which shows the receiving coil of the non-contact electric power supply which concerns on other embodiment of this invention. It is a top view which shows the receiving coil of the non-contact electric power feeder which concerns on other embodiment of this invention. It is sectional drawing which follows the OA line of FIG. It is sectional drawing which follows the OB line of FIG. It is a top view which shows a coil and a metal thermal conductor among the receiving coils of the non-contact electric power feeder which concerns on further another embodiment of this invention. It is sectional drawing which follows the VII-VII line of FIG. It is a graph which shows the resistance-frequency characteristic and inductance-frequency characteristic of the coil of the non-contact electric power supply which concern on this invention. It is a graph which shows the resistance-frequency characteristic and inductance-frequency characteristic of the coil of the non-contact electric power feeder which concerns on the comparative example of this invention. It is a figure which shows the model for estimating the temperature of the coil vicinity. It is a figure which shows the model for estimating the Joule heat which generate | occur | produces in a metal heat conductor. It is a graph which shows the relationship between the thickness of a metal heat conductor, coil vicinity temperature, and emitted-heat amount.

  FIG. 1 is a non-contact power feeding apparatus to which an embodiment of the present invention is applied, and includes a power receiving coil 10 and a power transmitting coil 20 positioned via a predetermined gap space 30, and is installed in a power feeding stand or the like. The present invention can be applied to a system in which electric power is supplied in a non-contact manner to a load such as a battery 50 mounted on a vehicle or the like and charged.

  The power receiving coil 10 includes a coil 11 made of a conductor such as copper. The coil 11 of this example is a flat coil wound at least on the xy plane, and is wound in a single (one step) on the xy plane as shown in FIG. Also included are those that are wound in multiple layers. In addition to the coil 11 wound in a plan view as shown in FIG. 2, the coil 11 of this example is wound in an elliptical shape in a plan view, or a rectangular shape such as a square or a rectangle. Also included are those which are wound around the shape of figure 8 or intersecting with the figure 8 shape. The surfaces of the conductors of the coil 11 of this example are insulated so as not to short-circuit each other, and both ends thereof are connected to the input terminals of the battery 50, respectively.

  Further, FIG. 2 shows the coil 11 of this example wound three times in a spiral shape in plan view. From the inner end point P1 to the point P2 counterclockwise is the first rotation, from the point P2 to the point P3 counterclockwise is the second rotation, and from the point P3 to the outer end point P4. Up to the third rotation. However, the number of windings is not limited to that shown in the figure, and can be appropriately set according to the use of power feeding.

  Returning to FIG. 1, a magnetic core 14 that adjusts the magnetic field from the power transmission coil 20 is provided over the entire surface of the coil 11 on the back surface of the coil 11 via the insulating portion 13. Further, on the back surface of the magnetic core 14, a magnetic shielding plate 15 that suppresses the magnetic fields from the power receiving coil 10 and the power transmitting coil 20 from reaching the back side of the power receiving coil 10 is provided. In order to protect the entire power receiving coil 10, a cover 16 that covers the entire power receiving coil 10 is provided. However, a part of the metal thermal conductor 12 described later is exposed from the cover 16 to the gap space 30. ing. This point will be described later.

  A metal thermal conductor 12 is provided between the coils 11 of the power receiving coil 10 of this example (between the coil wires). For the metal thermal conductor 12 of this example, a metal having high thermal conductivity such as aluminum can be used. In order to insulate between the metal heat conductor 12 and the coil 11 and between the metal heat conductors 12 adjacent to each other, the surface of the metal heat conductor 12 is coated with insulation.

  When the coil 11 is viewed in the winding direction, the metal thermal conductor 12 of this example is disposed between the wound coils 11 and preferably disposed in a direction orthogonal to the coil 11. Yes. Here, the term “arranged between the coils 11” means that the two ends of the metal thermal conductor 12 are at least wound in the plan view of the coil 11 in FIG. 2 and are in thermal contact with the two adjacent coils 11. Means that In other words, it means that the heat generated in the coil 11 due to the electromagnetic induction action is transmitted to the metal heat conductor 12 and can be used to radiate heat from here to the outside of the power receiving coil 10.

  As shown in FIG. 2, the metal heat conductor 12 can be arranged at an arbitrary interval along the winding direction of the coil 11, and is arranged so as to be continuously laminated along the winding direction of the coil 11. May be. When arrange | positioning so that the metal heat conductor 11 may be laminated | stacked continuously, the adjacent metal heat conductor 11 is insulated from each other.

The metal heat conductor 12 is formed so that the length in the extending direction disposed between the two coils is longer than the length in the non-stretching direction. That is, in terms of the xyz coordinates in FIG. 1, the extending direction arranged across the road corresponds to the y-axis direction, and the non-crossing direction corresponds to the x-axis direction (the direction along the winding direction of the coil 11). Therefore, the length in the y-axis direction is longer than the length in the x-axis direction. Note that the length in the z-axis direction is a length obtained by adding the exposure from the cover 26 described later to the thickness of the coil 11. As an example of the shape of the metal thermal conductor 11 that satisfies such conditions, a thin thin plate can be cited in the winding direction of the coil 11.

  As shown in FIG. 1, the metal heat conductor 12 is provided such that its lower surface is exposed from the cover 16 toward the gap space 30. Heat from the coil 11 transmitted from the exposed portion to the metal heat conductor 12 can be radiated to the gap space 30.

  The metal heat conductor 12 of this example is made of a thin plate-like metal that is long in the direction straddling the coils 11 (y-axis direction) and thin in the winding direction of the coil 11 (x-axis direction in FIG. 1). For example, since the aspect ratio is large and insulated from each other in the direction perpendicular to the magnetic flux, the generated eddy current is small, the resistance of the coil 11 due to the proximity effect, the heat generation of the thin metal heat conductor 12 itself, and other electromagnetic influences. There are few. Moreover, since the metal thermal conductor 12 with high thermal conductivity can be disposed in contact with the coil 11, heat dissipation from the coil is higher than when the resin is filled. For example, the thermal conductivity of aluminum is approximately 200 W / (mK), whereas the high thermal conductive resin is 1 to 2 W / (mK), and a large thermal conductivity is achieved by using the metal thermal conductor 12 that is a thin aluminum plate. The rate can be expected to improve.

  FIG. 8 shows measurement results of resistance and inductance when a laminated aluminum metal heat conductor 12 is arranged between the coils 11 according to this example. In the figure, ♦ indicates resistance-frequency characteristics and inductance-frequency characteristics when the aluminum metal heat conductor 12 is not disposed between the coils 11, and □ indicates the case where the aluminum metal heat conductor 12 is disposed between the coils 11. The resistance-frequency characteristics and the inductance-frequency characteristics are shown. Changes in resistance and inductance due to the presence or absence of the laminated aluminum metal heat conductor 12 are not observed.

On the other hand, when an aluminum metal heat conductor is disposed between the coils 11 as shown in the upper diagram of FIG. 9, the resistance of the coil 11 increases as shown in the lower left and right diagrams of FIG. A decrease was observed. This is presumably because an eddy current is generated in the aluminum metal heat conductor 12 'by the magnetic flux passing through the upper and lower surfaces and the side surfaces of the aluminum metal heat conductor 12', causing a proximity effect and a magnetic flux shielding effect. Therefore, when arranging a metal thermal conduction material such as aluminum in the vicinity of the coil 11, is arranged such eddy current is not generated becomes necessary.

で表される。ここで、熱抵抗は、金属熱伝導体１２の厚さと単位長さ当たりの層数による等価熱伝導率を用いる。金属熱伝導体１２の厚み（アルミニウムと樹脂との混合率）を上げることにより、コイル付近の温度を低減できる。 Next, the optimized shape of the metal heat conductor 12 will be considered. In order to increase the thermal conductivity, it is effective to increase the thickness of the portion of the metal thermal conductor 12 that is in contact with the coil 11. On the other hand, to suppress the eddy current of the metal thermal conductor 12, the thickness is reduced. It is necessary to insulate from each other by thinning according to the frequency. First, as shown in FIG. 10, the temperature T _{2 in} the vicinity of the coil 11 has a thermal resistance 1 / KA, a steady heat generation amount Q per unit length, and an ambient temperature T ₁ .

It is represented by Here, the thermal resistance uses an equivalent thermal conductivity according to the thickness of the metal thermal conductor 12 and the number of layers per unit length. By increasing the thickness of the metal heat conductor 12 (mixing ratio of aluminum and resin), the temperature near the coil can be reduced.

発生する起電圧Ｖ（ｔ，ｘ）と実効値Ｖ_ｅｆｆは、それぞれ下記のようになる。

On the other hand, as shown in FIG. 11, the metal thermal conductor 12 is a flat plate having vertical aX, horizontal X, and height L, and when the magnetic flux of B ₀ sin ωt is linked perpendicularly to the metal thermal conductor 12 The Joule heat generated in 12 flat plates is estimated. The magnetic flux φ (t, x) interlinking the longitudinal ax and lateral x regions is the interlinkage magnetic flux density B ₀ , the angular frequency ω, the electrical conductivity σ of the metal thermal conductor 12, and the magnetic permeability μ of the metallic thermal conductor 12. As

The generated electromotive voltage V (t, x) and effective value V _eff are as follows.

となり、金属熱伝導体１２に発生するジュール熱は、上記電流によるジュール熱を平板領域で積分（０〜ｘ〜Ｘ）することにより、下記のようになる。

Assuming that a current due to the electromotive voltage is generated in the circulation path of the widths dx and adx, the resistance dr (x) at that portion is

Thus, the Joule heat generated in the metal thermal conductor 12 is as follows by integrating (0 to x to X) the Joule heat generated by the current in the flat plate region.

Here, when the frequency is sufficiently high, the thickness L at which the current is generated is represented by the skin thickness.

From the above, after all, the Joule heat generated in one flat plate can be estimated as follows.

より、

ただし、

The thickness of the insulating layer between the thin plates as the metal heat conductor 12 is set to 0.1 mm, and the mixing ratio of aluminum and resin is changed according to the thickness of the thin plate (for example, if the mixing ratio is 50%, the thin plate The thickness is also set to 0.1 mm, which is the same as the insulating layer), and plotted together with Joule heat, the result is as shown in FIG. For example, when the value of a is determined so that the total Joule heat of the metal heat conductor 12 becomes 1 / k of the steady output P, (n is the number of thin plates)

Than,

However,

  By selecting the largest value a that satisfies the above formula 9, it is possible to achieve both thermal performance and electromagnetic performance.

  Returning to FIG. 1, the power transmission coil 20 has the same structure as that of the power reception coil 10 described above. As members corresponding to the coil 11, the metal heat conductor 12, the insulating portion 13, the magnetic core 14, the magnetic shielding plate 15, and the cover 16 of the power receiving coil 10, the power transmission coil 20 includes the coil 21, the metal heat conductor 22, and the insulation. A portion 23, a magnetic core 24, a magnetic shielding plate 25, and a cover 26 are provided. Note that the metal thermal conductors 12 and 22 of the present invention may be provided in at least one of the power receiving coil 10 or the power transmitting coil 20.

  As described above, according to the non-contact power feeding device 1 of the present example, the metal thermal conductor 12 is long in the direction across the coils 11 (y-axis direction), and the winding direction of the coil 11 (x-axis in FIG. 1). In other words, it has a large aspect ratio with respect to the direction perpendicular to the magnetic flux and is insulated from each other. Therefore, the generated eddy current is small, the resistance of the coil 11 due to the proximity effect, and the thin plate. There are few electromagnetic influences, such as heat_generation | fever of the metal heat conductor 12 itself.

  Further, by selecting the largest value a that satisfies the above formula 9, it is possible to achieve both thermal performance and electromagnetic performance.

  Further, since a part of the metal heat conductor 12 is exposed to the gap space 30 side of the coil 11, the coil can be effectively subjected to heat exchange by natural convection with the outside air of the gap space 30 or forced air cooling by a fan or the like. 11 can be removed.

  FIG. 3 is a cross-sectional view showing a power receiving coil 10 according to another embodiment of the present invention. In this example, a part of the metal thermal conductor 12 exposed in the gap space 30 is connected by a connecting portion 12a. Yes. By carrying out like this, since the metal thermal conductor 12 can be contacted by the upper surface and both sides | surfaces of the coil 11, the thermal resistance of the coil 11 can be reduced and the heat dissipation effect can be increased. Further, the coil 11 can be positioned by the metal heat conductor 12. Furthermore, the coil 11 can be protected when a force is applied to the non-contact power feeding device 1. That is, the resistance value of the coil 11 generally increases with frequency, but the value is also affected by how the coil 11 is wound (such as how to twist parallel coils) and arrangement (clearance between the coils). After winding the coil 11 in a predetermined winding method, the conventional example is hardened with resin so that the position does not change even when a force is applied from the outside. The effect can be expected.

4 is a plan view showing a power receiving coil 10 according to still another embodiment of the present invention, FIG. 5A is a cross-sectional view taken along line OA in FIG. 4, and FIG. 5B is taken along line OB in FIG. It is sectional drawing. In this example, two coils 11 are used in parallel, and the coils 11 are twisted to increase the Q value indicating the sharpness of resonance. In this case, since the clearance between the wires of the coil 11 in the circumferential direction changes with the angle, as shown in FIGS. 5A and 5B, the length of the side perpendicular to the coil 11 of the metal thermal conductor 12 is matched to the clearance. W _A and W _B are changed. Thus, the arrangement of the metal thermal conductor 12 shaped so as to be in contact with the wire of the coil 11 is effective in terms of heat dissipation.

  FIG. 6 is a plan view showing a power receiving coil 10 according to still another embodiment of the present invention, and FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. In this example, the other metal heat conductors 17 that are connected to one surface of the plurality of metal heat conductors 12 exposed in the gap space 30 and extend in the winding direction of the coil 11 are arranged. By providing the other metal heat conductor 17, the heat radiation area of the metal heat conductor 12 can be increased, and the heat radiation effect can be enhanced. Further, by arranging the flat metal heat conductor 17 in the gap space 30 away from the coil 11, an increase in coil resistance due to the proximity effect can be suppressed.

  The power receiving coil 10 or the power transmitting coil 20 corresponds to a coil according to the present invention.

DESCRIPTION OF SYMBOLS 1 ... Non-contact electric power feeder 10 ... Power receiving coil 11 ... Coil 12 ... Metal thermal conductor 12a ... Connection part 13 ... Insulation part 14 ... Magnetic core 15 ... Magnetic shielding board 16 ... Cover 17 ... Other metal thermal conductors 20 ... Power transmission Coil 21 ... Coil 22 ... Metal thermal conductor 23 ... Insulating part 24 ... Magnetic core 25 ... Magnetic shielding plate 26 ... Cover 30 ... Gap space

Claims (7)

In a non-contact power feeding device that feeds power between a pair of coils formed by winding at least one coil in a non-contact manner,
When the coil formed by winding is viewed in the winding direction, the coil is disposed between the wound coils, and the length in the direction in which the length of the extending direction is not straddled is disposed. The non-contact electric power feeder provided with the nonmagnetic metal heat conductor formed longer than the length. The metal heat conductor is
Formed into a thin plate,
Insulated with the coil arranged across,
The non-contact electric power feeder of Claim 1 arrange | positioned orthogonally to the coil arrange | positioned across the said straddle.   The non-contact electric power feeder of Claim 2 with which the metal heat conductor arrange | positioned orthogonally to the said coil is provided in contact with the said coil according to the space | interval of the said coil.   The contactless power feeding device according to any one of claims 1 to 3, wherein a part of the metal heat conductor is exposed in a gap space between the pair of coils.   The non-contact electric power feeder according to claim 4 with which a part of metallic heat conductor exposed to said gap space is connected.   The other metal heat conductor which connects these and is extended to the winding direction of the said coil is arrange | positioned on one surface of the some metal heat conductor exposed to the said gap space, The Claim 4 or 5 is arrange | positioned. Non-contact power feeding device. The sheet metal heat conductor is
The conductivity of the metal heat conductor is σ, the length of the long side of the metal heat conductor is X, the magnetic permeability of the metal heat conductor is μ, the number of metal heat conductors is n, and the angular frequency of the feed power is ω , When the flux linkage density is B ₀ and the metal heat conductor plate thickness / long side length ratio is a,
a ³ −Ka ² −K <0
However, K = {16P · √ (σωμ / 2)} / nkσ ² B ₀ ² X ⁴
The non-contact electric power feeder as described in any one of Claims 2-6 which satisfy | fills.

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