JP2020178034A - Non-contact power supply transmission coil unit, manufacturing method thereof, and non-contact power supply device - Google Patents

Abstract

To provide a non-contact power supply transmission coil unit that reduces high frequency loss due to coil skin effect and proximity effect, suppresses an increase in AC resistance, and can be manufactured at low cost, and a non-contact power supply device with high transmission efficiency using a transmission coil unit.SOLUTION: A non-contact power supply transmission coil unit includes a coil 2 wound in a spiral, and a magnetic shield 3 arranged so as to face the coil surface of the coil 2, and the coil cross-sectional shape in the winding direction of a coil conductor of each winding has a shape portion that follows the flow of a magnetic flux line generated when the coil 2 is energized.SELECTED DRAWING: Figure 3

Description

The present invention relates to a non-contact power supply transmission coil unit, a method for manufacturing a non-contact power supply transmission coil unit, and a non-contact power supply device capable of transmitting electric power in a non-contact manner with high efficiency.

In recent years, the use of an electromagnetic induction type wireless power feeding device has been studied for charging the battery of a vehicle such as an electric vehicle or a hybrid vehicle. In the wireless power feeding device, a high-frequency strong current (generally several tens of kHz to 200 kHz, several tens of amperes) is applied to the power transmission coil, and the power receiving coil receives the high-frequency magnetic field generated from the power transmission coil to transmit power in a non-contact manner.

In such a non-contact power feeding device, a planar coil having a spiral shape and a rectangular cross section is used in order to cope with the thinning of the device. Further, in order to prevent an eddy current from being generated in surrounding metal parts due to a high frequency magnetic field and abnormal heat generation, a magnetic shield made of ferrite or the like is arranged near the coil (for example, Patent Document 1). The transmission coil unit is composed of a combination of a flat coil and a magnetic shield.

In the transmission coil unit, when the coil is energized, magnetic flux lines are generated so as to surround the coil cross section. Since the magnetic flux lines have high magnetic permeability of the magnetic shield, they are distributed so as to flow substantially vertically from the surface of the magnetic shield. Further, although the coil is formed by winding one conducting wire, it may be considered that a plurality of conductors (coil conductors) are equivalently arranged close to each other. Therefore, the coil has both a skin effect due to the current flowing through the coil and a proximity effect due to the eddy current generated in the adjacent coil conductor. Therefore, the current flowing through each coil conductor is biased inside the conductor, and in particular, the inner peripheral portion of the coil is biased toward the inner peripheral side inside the coil conductor, and the outer peripheral portion is biased toward the outer peripheral side inside the coil conductor. Therefore, the current is concentrated in those parts and the magnetic flux lines are also concentrated.

However, since the conventional coil is a flat coil having a rectangular cross section, the high frequency skin thickness is thin, and the cross-sectional area of the coil conductor in the portion where the above current is concentrated flows is small. Therefore, the AC resistance increases, and the decrease in power transmission efficiency becomes a problem.

On the other hand, it is known to use a litz wire obtained by twisting a large number of insulating strands as a coil winding (for example, Patent Document 2). The litz wire is a wire obtained by combining a large number (for example, 500 or more) of thin strands (for example, enamel wire having a diameter of 0.1 mm or less). It is possible to suppress high frequency loss due to the skin effect and proximity effect. However, the litz wire having a thin wire and a large number of wires has a problem that the manufacturing cost is high.

Japanese Unexamined Patent Publication No. 2013-201296 JP-A-2016-219252

Therefore, in view of the above circumstances, the present invention provides a transmission coil unit for non-contact power feeding that can be manufactured at low cost by reducing high frequency loss due to the skin effect and proximity effect of the coil and suppressing an increase in AC resistance. The purpose is to do.

The non-contact power supply transmission coil unit of the present invention is for non-contact power supply including a coil wound in a spiral shape and a magnetic shield arranged so as to face the coil surface of the coil at a predetermined distance. The transmission coil unit has a portion in which the coil cross-sectional shape in the winding direction of the coil conductor of each winding is along the magnetic flux line generated when a current flows through the coil.

The cross-sectional shape of the coil is rectangular, and the longitudinal direction of the rectangular shape is substantially perpendicular to the magnetic shield surface of the magnetic shield at the inner peripheral portion and the outer peripheral portion of the coil, and the inner peripheral portion and the outer peripheral portion. The rectangular shape is substantially parallel to the magnetic shield surface at the central portion between the two, and the angle in the longitudinal direction of the rectangular shape is between the inner peripheral portion and the central portion and between the central portion and the outer peripheral portion. It may change stepwise between departments.

The cross-sectional shape of the coil may be U-shaped, and the U-shaped recess may face the magnetic shield surface.

It is provided with a non-magnetic insulator having a rectangular planar shape, a spiral groove having a straight side portion and an arc portion at a corner portion, and the coil is continuously provided in the groove. Good.

The non-magnetic insulator may be a resin having a thermal conductivity of 1 W / (mK) or more.

At least the side surface of the coil conductor may be directly or indirectly in contact with the non-magnetic insulator.

The ratio of the side length to the width of the upper surface of the U-shape is the maximum at the inner peripheral portion and the outer peripheral portion of the coil, the minimum at the central portion between the inner peripheral portion and the outer peripheral portion, and the said. The ratio may change stepwise between the inner peripheral portion and the central portion and between the central portion and the outer peripheral portion.

A magnetic layer may be formed on at least the surface and the side surface of the coil cross-sectional shape opposite to the surface facing the magnetic shield surface.

The method for manufacturing the non-contact power supply transmission coil unit may include a step of spirally grooving the metal flat plate by laser processing or press working, and a step of deforming the grooved metal flat plate by press working. Good.

The method for manufacturing the non-contact power feeding transmission coil unit includes a step of grooving a metal flat plate in a spiral shape by laser processing or press working, a step of deforming the grooved metal flat plate by press working, and a groove. A step of forming a magnetic layer on the surface of the metal flat plate that has been cut may be included.

In the non-contact power feeding device of the present invention, the non-contact power transmission transmission coil unit may be used as a power transmission coil or as a power transmission coil and a power reception coil.

With the above configuration, the current is concentrated in the portion where the magnetic flux lines are concentrated inside the coil conductor of each winding. Further, the coil cross-sectional shape in the winding direction of the coil conductor of each winding has a shape portion that follows the flow of magnetic flux lines generated when the coil is energized. Therefore, the current is concentrated in this shape portion where the magnetic flux lines are concentrated. However, since this shaped portion follows the flow of magnetic flux lines, it occupies a large area in the cross section of the coil conductor. Therefore, as a result, the AC resistance of the coil can be reduced.

Further, by fixing the coil so as to be embedded in the non-magnetic insulator, vibration of the coil at the time of feeding can be suppressed. Further, the heat of the coil can be released to the non-magnetic insulator, and as a result, an increase in DC resistance due to heat generation of the coil itself can be suppressed.

Further, by forming a magnetic layer on the surface and side surface of the cross-sectional shape of the coil conductor, which is at least opposite to the surface facing the magnetic shield surface, the magnetic flux lines concentrated on the surface and side surface of the coil conductor are magnetic. The number of magnetic flux lines that can be guided to the layer and penetrate the coil conductor can be reduced. As a result, the eddy current in the coil conductor can be suppressed and the AC resistance of the coil can be further reduced.

Further, the transmission coil unit can be manufactured at low cost by processing the metal flat plate into a spiral coil shape by laser processing or press processing. Further, by providing the magnetic layer on the coil surface, the eddy current in the coil conductor can be further suppressed, and the transmission coil unit can be manufactured easily and at low cost.

Further, by using a transmission coil unit that can be manufactured at low cost while reducing high frequency loss due to the skin effect and proximity effect, it is possible to provide a non-contact power feeding device having high transmission efficiency and low cost.

It is a top view of the plane of the transmission coil unit which concerns on 1st to 4th Embodiment. It is sectional drawing of the transmission coil unit which concerns on 1st Embodiment. It is sectional drawing of the transmission coil unit which concerns on 2nd Embodiment. It is sectional drawing of the transmission coil unit which concerns on 3rd Embodiment. It is sectional drawing of the transmission coil unit which concerns on 4th Embodiment. It is sectional drawing of the transmission coil unit which concerns on 5th Embodiment. It is a top view of the transmission coil unit which concerns on 5th Embodiment. It is sectional drawing of the coil conductor of the coil of the transmission coil unit which concerns on 6th Embodiment. It is a block diagram explaining the manufacturing process of the coil of the transmission coil unit which concerns on 7th Embodiment. It is a block diagram explaining the manufacturing process of the coil of the transmission coil unit which concerns on 8th Embodiment. It is a circuit block diagram explaining the non-contact power feeding apparatus which concerns on 9th Embodiment. It is a figure (plan view) explaining the calculation model of a coil. It is sectional drawing of the coil of the transmission coil unit of Example 1. FIG. It is sectional drawing of the coil and the magnetic shield of the transmission coil unit of Example 2. FIG. It is sectional drawing of the coil and the magnetic shield of the transmission coil unit of Example 3. FIG. It is sectional drawing of the coil and the magnetic shield of the transmission coil unit of the comparative example 1. FIG. It is sectional drawing of the coil of the transmission coil unit of Example 12. FIG. It is a graph which shows the actual measurement result of the coil of the transmission coil unit of Example 12.

A transmission coil unit according to an embodiment of the present invention, a method for manufacturing the same, and a non-contact power feeding device using the transmission coil unit will be described with reference to the drawings.

<1. Transmission coil unit>
(First Embodiment)
FIG. 1 is a schematic plan view of a transmission coil unit according to the first to fourth embodiments. The transmission coil unit 1 includes a flat coil 2 in which a coil conductor 21 made of aluminum or copper metal is spirally wound, and a magnetic shield 3 arranged so as to oppose the coil surface of the coil 2. There is. In this example, the coil 2 is a flat coil having 6 turns and an alpha winding. Further, as the magnetic shield 3, various ferrite materials such as a Ni-based ferrite sintered body and an Mn-based ferrite sintered body can be used, but a NiMn-based ferrite sintered body having a high resistivity is more preferable. Further, an electric shield 4 made of aluminum or copper metal is arranged so as to face the surface of the magnetic shield 3 opposite to the coil 2.

FIG. 2 is a schematic cross-sectional view of the transmission coil unit according to the first embodiment, and is a cross-sectional view taken along the line AA'of FIG. The magnetic flux line 5 generated by energizing the coil 2 with an electric current is shown by a dotted line. The coil cross-sectional shape of the coil conductor 21 of each winding in the winding direction has a shape portion along the flow of the magnetic flux line 5 generated when the coil 2 is energized.

That is, in this example, the cross-sectional shape of the coil conductor 21 of each winding is rectangular, and the longitudinal direction of the rectangular shape is substantially equal to the surface (magnetic shield surface) of the magnetic shield 3 at the inner peripheral portion 22 and the outer peripheral portion 24 of the coil. It is vertical and is substantially parallel to the magnetic shield surface at the central portion 23 between the inner peripheral portion 22 and the outer peripheral portion 24. Further, the angle of the rectangular shape in the longitudinal direction with respect to the magnetic shield surface changes stepwise from the inner peripheral portion 22 to the central portion 23 and from the central portion 23 to the outer peripheral portion 24.

The coil 2 is a spiral flat coil, and the coil conductor 21 is continuously wound from the inner peripheral portion to the outer peripheral portion of the winding. Therefore, as a method of winding the coil conductor 21, the angle in the longitudinal direction of the rectangular shape with respect to the magnetic shield surface is the same during one rotation of the winding, and it changes little by little or gradually with each rotation. The angle changes gently and continuously during one circumference of the coil, and when viewed in a cross section passing through the center of the spiral coil, the angle gradually changes from the inner peripheral portion 22 to the outer peripheral portion 24 of the coil. In any case, it does not matter.

The magnetic flux line 5 surrounding the coil 2 is generated substantially perpendicularly from the magnetic shield surface of the magnetic shield 3 at the inner peripheral portion 22 of the coil, flows substantially parallel to the coil conductor at the central portion 23, and becomes the magnetic shield 3 at the outer peripheral portion 24. It flows almost vertically.

In the first embodiment, the coil conductor 21 is arranged so that the longitudinal direction of its rectangular cross section is along the magnetic flux line 5, and the rectangular shape corresponds to the shape portion along the flow of the magnetic flux line 5.

In FIG. 2, the portion where the magnetic flux lines are concentrated and the current is substantially concentrated inside the coil conductor 21 of each winding is shown in gray. The concentration of the magnetic flux lines 5 and the current in the coil conductor 21 is on the inner peripheral side of the coil conductor 21 at the inner peripheral portion 22 of the coil, on the outer peripheral side of the coil conductor 21 at the outer peripheral portion 24 of the coil, and further at the inner peripheral portion 22. In the central portion 23 between the outer peripheral portion 24 and the outer peripheral portion 24, the coil conductor 21 is formed on the surface opposite to the surface facing the magnetic shield 3 and on the opposite side.

As described above, in the first embodiment, the coil cross-sectional shape of the coil conductor 21 in the winding direction has a rectangular shape of a shape portion along the flow of the magnetic flux line 5. As a result, the cross-sectional area of the current-concentrated portion can be increased, and an increase in AC resistance can be suppressed.

In this embodiment, the coil cross-sectional shape is rectangular and the longitudinal direction of the rectangular shape coincides with the direction of the magnetic flux line 5, but the coil cross-sectional shape is not limited to the rectangular shape. The coil cross-sectional shape may be another shape as long as the longitudinal direction of the coil cross-sectional shape is substantially aligned with the flow of the magnetic flux line 5 or has a component that is aligned with the flow.

(Second Embodiment)
FIG. 3 is a schematic cross-sectional view of the transmission coil unit according to the second embodiment. The schematic plan view of the transmission coil unit according to the second embodiment may be the same as that in FIG. FIG. 3 is a cross-sectional view taken along the line AA'of FIG. 1 of the schematic plan view.

The transmission coil unit 1 includes a flat coil 2 in which a coil conductor 21 made of aluminum or copper metal is spirally wound, and a magnetic shield 3 arranged so as to face the coil surface of the coil 2. There is. As the magnetic shield 3, various ferrite materials such as a Ni-based ferrite sintered body and a Mn-based ferrite sintered body can be used, but a NiMn-based ferrite sintered body having a high resistivity is more preferable. The electric shield is omitted and not shown.

The coil cross-sectional shape of the coil conductor 21 in the winding direction is U-shaped, and the U-shaped recess faces the magnetic shield surface. The magnetic flux lines generated by energizing the coil 2 are concentrated in the portion shown in gray inside the coil conductor 21 of each winding, and the current is also concentrated in this portion. This portion corresponds to a shape portion along the flow of the magnetic flux line 5.

That is, in the inner peripheral portion 22 of the coil 2, the L-shaped portion on the inner peripheral side of the U-shape roughly corresponds to the shape portion along the flow of the magnetic flux line 5, and in the outer peripheral portion 24, the outer peripheral side of the U-shape. The L-shaped portion roughly corresponds to the shape portion along the flow of the magnetic flux line 5, and in the central portion 23, the flat portion on the side opposite to the U-shaped magnetic shield surface is approximately the flow of the magnetic flux line 5. Corresponds to the shape part along. Therefore, it can be said that the coil 2 of the transmission coil unit 1 according to the second embodiment has a shape portion along the flow of the magnetic flux line 5. As a result, the increase in AC resistance is suppressed.

In this example, the same U-shaped coil conductor 21 is repeatedly arranged, but the coil cross-sectional shape of the coil conductor 21 of each winding does not necessarily have to be the same.

The coil 2 of the transmission coil unit according to the second embodiment can be easily and inexpensively manufactured by laser processing or press processing described later.

(Third Embodiment)
FIG. 4 is a schematic cross-sectional view of the transmission coil unit according to the third embodiment. The schematic plan view of the transmission coil unit according to the third embodiment may be the same as that in FIG. 1, and FIG. 4 is a cross-sectional view taken along the line AA'of FIG. 1 of the schematic plan view.

The transmission coil unit 1 includes a flat coil 2 in which a coil conductor 21 made of aluminum or copper metal is spirally wound, and a magnetic shield 3 arranged so as to face the coil surface of the coil 2. There is. As the magnetic shield 3, various ferrite materials such as a Ni-based ferrite sintered body and a Mn-based ferrite sintered body can be used, but a NiMn-based ferrite sintered body having a high resistivity is more preferable. The electric shield is omitted and not shown.

The coil 2 of the transmission coil unit 1 according to the third embodiment has a U-shaped coil cross-sectional shape and is U-shaped, similarly to the coil 2 of the transmission coil unit 1 according to the second embodiment. The letter-shaped recess faces the magnetic shield surface. The ratio of the side length 26 to the U-shaped upper surface width 25 is maximum at the inner peripheral portion 22 and the outer peripheral portion 24 of the coil, and is minimum at the central portion 23 between the inner peripheral portion 22 and the outer peripheral portion 24. is there. Further, the ratio of the side surface length 26 to the upper surface width 25 changes stepwise between the inner peripheral portion 22 and the central portion 23 and between the central portion 23 and the outer peripheral portion 24.

The coil 2 is a spiral flat coil, and the coil conductor 21 is continuously wound from the inner peripheral portion 22 to the outer peripheral portion 24. Therefore, as a method of winding the coil conductor 21, the ratio of the side length to the upper surface width of the U-shape is the same during one rotation of the winding, and whether it changes little by little with each rotation. Alternatively, the ratio gradually and continuously changes during one circumference of the coil, and when viewed in a cross section passing through the center of the spiral coil, it gradually changes from the inner peripheral portion 22 to the outer peripheral portion 24 of the coil. In any case, it does not matter.

The coil 2 of the third embodiment has a structure having two features of the first embodiment and the second embodiment. That is, the coil cross-sectional shape of the coil conductor 21 of each winding of the coil 2 of the third embodiment is U-shaped like the coil 2 of the second embodiment, and is formed with the inner peripheral portion 22 of the coil 2. The outer peripheral portion 24 has a substantially rectangular shape close to the cross section of the coil conductor 21 of the coil 2 of the first embodiment, and its longitudinal direction is substantially perpendicular to the magnetic shield surface of the magnetic shield 3, so that the magnetic flux line 5 is formed. It has a shape part that follows the flow. Further, the central portion 23 of the coil 2 also has a substantially rectangular shape close to the cross section of the coil conductor 21 of the coil 2 of the first embodiment, and its longitudinal direction is substantially parallel to the magnetic shield surface, so that the magnetic flux lines It has a shape portion along the flow of 5. Then, between the inner peripheral portion 22 and the central portion 23 and between the central portion 23 and the outer peripheral portion 24, a U-shaped L-shaped portion follows the flow of the magnetic flux line 5 as in the first embodiment. The cross-sectional shape of the coil is gradually changed so as to correspond to the shape portion. As a result, an increase in the AC resistance of the coil 2 is suppressed.

The coil 2 of the transmission coil unit according to the third embodiment can be easily and inexpensively manufactured by laser processing or press processing described later.

(Fourth Embodiment)
FIG. 5 is a schematic cross-sectional view of the transmission coil unit according to the fourth embodiment. The transmission coil unit according to the fourth embodiment has basically the same structure as the transmission coil unit according to the first embodiment, but the magnetic layer 6 is formed on the entire surface of the coil conductor 21. It differs in that.

Here, the magnetic flux lines concentrated on the inner peripheral side and the outer peripheral side of the coil conductor 21 are guided so as to be attracted to the magnetic layer 6 having a high magnetic permeability, and the concentration of the magnetic flux lines is eliminated inside the coil conductor 21. As a result, the current concentration inside the coil conductor 21 is also eliminated, and as a result, an increase in the AC resistance of the coil 2 can be further suppressed. In terms of eliminating the concentration of magnetic flux lines, the surface (upper surface) and edge of the coil conductor 21 on the side opposite to the surface facing at least the magnetic shield surface of the coil conductor 21 are not the entire surface of the coil. The magnetic layer 6 may be formed on the side surface including the magnetic layer 6.

(Fifth Embodiment)
FIG. 6 shows a schematic cross-sectional view of a fifth embodiment of the present invention. In FIG. 6, the coil 2 is a spiral flat coil, and is continuously wound from the inner peripheral portion to the outer peripheral portion. Further, the coil cross-sectional shape of the coil conductor 21 of each winding is U-shaped like the coil 2 of the second embodiment.

The transmission coil unit 1 includes a flat coil 2 in which a coil conductor 21 made of aluminum or copper metal is spirally wound, and a magnetic shield 3 arranged so as to face the coil surface of the coil 2. There is. As the magnetic shield 3, various ferrite materials such as a Ni-based ferrite sintered body and a Mn-based ferrite sintered body can be used, but a NiMn-based ferrite sintered body having a high resistivity is more preferable. The electric shield is omitted and not shown.

The present embodiment differs from the second embodiment in that a non-magnetic insulator 41 is provided between the magnetic shield 3 and the coil 2. A plan view of the non-magnetic insulator 41 and the coil 2 is shown in FIG. In FIG. 7, the non-magnetic insulator 41 is formed with spiral grooves having straight side portions and arcuate corner portions and having a rectangular planar shape as a whole. Further, the coil 2 is continuously provided in the groove of the non-magnetic insulator 41. The non-magnetic insulator is preferably a material having a relatively high thermal conductivity, such as ceramic. Further, a resin containing glass fiber or an inorganic filler may be used. The thermal conductivity of the non-magnetic insulator 41 is preferably 1 W / (mK) or more.

At least the side surface of the coil conductor 21 of each winding in the coil 2 is in direct or indirect contact with the groove of the non-magnetic insulator 41. For example, the coil 2 may be fitted in the groove of the non-magnetic insulator 41, or an adhesive layer (not shown) may be provided between the coils 2. Since at least the side surface of the coil conductor 21 of each winding is in contact with the groove of the non-magnetic insulator 41, the lower side of the coil 2 is embedded in the non-magnetic insulator 41 and fixed. There are two effects of this configuration.

One is the effect of suppressing the vibration of the coil 2. That is, in the present embodiment, since the coil 2 is formed of a metal flat plate, it has high elasticity unlike the litz wire. In other words, there is a natural frequency determined by the elasticity, shape and mass of the coil 2. When alternating current flows through the coil 2, if the coil 2 is left in a deformable state, the natural vibration of the coil 2 is excited by the interaction with the magnetic shield 3 and the coil (not shown) of the feeding destination. There are times. However, if the coil 2 is embedded and fixed in a non-magnetic insulator 41 having high rigidity or viscosity, such vibration can be suppressed.

Further, since the coil 2 is embedded in the non-magnetic insulator 41, the effect of heat dissipation of the coil 2 can be expected. Insulators generally have low thermal conductivity, but insulating resins with increased thermal conductivity, such as nylon resin mixed with an appropriate insulating filler and high thermal conductivity PPS (H718LB (TORAY), etc.), have recently been put into practical use. It is becoming a plastic.

In the present embodiment, the U-shaped cross-sectional shape of the coil conductor 21 may be changed at the inner peripheral portion, the central portion, and the outer peripheral portion as in the third embodiment (FIG. 4). The width and depth of the groove of the non-magnetic insulator 41 may also be changed according to the change in the cross-sectional shape of the coil conductor 21.

(Sixth Embodiment)
FIG. 8 is a schematic cross-sectional view of the coil conductor of the coil of the transmission coil unit according to the sixth embodiment. The transmission coil unit according to the present embodiment has basically the same structure as the transmission coil unit according to the second embodiment and the fifth embodiment, and has at least a magnetic shield having a coil cross-sectional shape of the coil conductor 21. The difference is that the magnetic layer 6 is formed on the surface and the side surface opposite to the surface facing the surface. In FIG. 8, (A) is on the upper surface of the U-shape and the surfaces of both left and right sides, (B) is on the surface of the surface facing the magnetic shield surface, (C) is on the inner surface of the recess. This is also the case when the magnetic layer 6 is formed on the entire surface of the U-shaped coil cross-sectional shape.

FIG. 8D is a partial cross-sectional view showing an example in which a magnetic material is provided in the coil 2 of the fifth embodiment (FIG. 4). When the coil 2 of the fifth embodiment is provided with a magnetic material, the coil 2 may be coated with the magnetic material in advance as shown in FIGS. 8A to 8C and then fitted into the non-magnetic insulator 41. It is good, but as shown in FIG. 3D, after the coil 2 is attached (or bonded) to the non-magnetic insulator 41, the upper surface and the edge of each coil conductor 21, that is, the portion exposed from the non-magnetic insulator 41. Only the magnetic material 6 may be provided.

Also in the present embodiment, as in the fourth embodiment, the magnetic flux lines concentrated on the inner peripheral side and the outer peripheral side of the coil conductor 21 are guided so as to be attracted to the magnetic layer 6 and inside the coil conductor 21. The concentration of magnetic flux lines is eliminated. As a result, the current concentration inside the coil conductor 21 is also eliminated, and as a result, an increase in the AC resistance of the coil 2 can be further suppressed.

<2. Manufacturing method of transmission coil unit>
(7th and 8th embodiments)
FIG. 9 is a block diagram illustrating a coil manufacturing process of the transmission coil unit according to the seventh embodiment. The coil manufacturing method of the transmission coil unit is as follows: grooving step S1 for producing a spiral flat coil by grooving a thin metal flat plate in a spiral shape by laser processing or press working, and the grooving metal flat plate. The coil of the transmission coil unit according to the first to third and sixth embodiments described above is manufactured through these steps, including the deformation step S2 of deforming the flat coil plate made of the above by press working.

For example, the transmission coil unit of the first embodiment is deformed by press working with a spiral metal flat plate sandwiched vertically in the deformation step S2 after the grooving step S1, and the angle of the cross section is stepwise. Form a coil with a changing rectangular cross section. At this time, the angle of the cross section is the same during one circumference of the winding, and may be changed stepwise little by little with each rotation, or the angle may be gently and continuously during one circumference of the coil. It may be changed so that the angle changes stepwise from the inner circumference to the outer circumference of the coil each time it makes one round.

Further, for example, the transmission coil units of the second and third embodiments have a cross-sectional shape obtained by press working with a male mold and a female mold in the post-deformation step S2 of the spiral grooving step S1. Form a C-shaped coil. At this time, with respect to the transmission coil unit of the third embodiment, the depth of the groove of the male type and the female type is the same during one rotation of the winding, and the depth is changed stepwise little by little with each rotation. The depth of the groove is gradually and continuously changed during one circumference of the coil, and when viewed in a cross section passing through the center of the spiral coil, the groove is formed from the inner circumference to the outer circumference of the coil. Pressing may be performed so that the depth angle changes stepwise.

FIG. 10 is a block diagram illustrating a coil manufacturing process of the transmission coil unit according to the eighth embodiment. The method for manufacturing the coil of the transmission coil unit according to this embodiment is the step of manufacturing the coil of the transmission coil unit according to the embodiment shown in FIG. 9, and the magnetic layer forming step S3 for further forming a magnetic layer on the coil conductor surface. It is an addition. As a result, the coil of the transmission coil unit according to the fourth to sixth embodiments described above is manufactured.

As a method of forming the magnetic layer on the surface of the coil conductor, in addition to the method of forming the magnetic layer by wet or dry plating, the powdered magnetic material is mixed with a solvent such as epoxy resin and applied by spraying or brushing. There is a way to do it. As the magnetic material, in addition to a ferromagnetic material such as iron and nickel and silicon steel to which Si and the like are added, amorphous, sendust, metal oxide (ferrite) and the like can be used. Any form of material such as thin film or nanopowder can be used.

<3. Non-contact power supply device>
(9th embodiment)
FIG. 11 is a circuit block diagram illustrating a non-contact power feeding device according to a ninth embodiment. In this example, it is applied to an electric vehicle. This non-contact power feeding device includes a power transmitting device 7 that functions as a charger and a power receiving device 8 that includes a battery 84 that serves as a power source for the automobile main body 9. The power transmitting device 7 and the power receiving device 8 are electromagnetically coupled to form a non-contact power feeding device that transmits power in a non-contact manner.

As shown in FIG. 11, the power transmission device 7 includes a power supply 71, a rectifier circuit 72, a power transmission circuit 73, and a power transmission coil 74. The power supply 71 is a system power supply that supplies a three-phase AC voltage such as 200V or 400V or a single-phase AC voltage of 100V. The rectifier circuit 72 has an input end connected to the power supply 71 and an output end connected to the power transmission circuit 73, rectifies the AC voltage supplied from the power supply 71, converts it into a DC voltage, and converts the converted DC voltage into a DC voltage. Output to the transmission circuit 73. The power transmission circuit 73 has an input end connected to a rectifying circuit 72 and an output end connected to both ends of a power transmission coil 74, and uses a DC voltage from the rectifying circuit 72 to generate an alternating current of a predetermined frequency. The generated AC voltage is supplied to the transmission coil 74.

As shown in FIG. 11, the power receiving device 8 includes a power receiving coil 81, a power receiving circuit 82, a charge / discharge control circuit 83, and a battery 84.

When the power receiving coil 81 is used so as to be close to and opposed to the power transmission coil 74 of the power transmission device 7, both coils 81 and 74 are electromagnetically coupled to form a transformer between them. The AC voltage induced in the power receiving coil 81 by this electromagnetic induction is supplied to the power receiving circuit 82, rectified in the power receiving circuit 82, and converted into a DC voltage. The DC voltage output from the power receiving circuit 82 is supplied to the battery 84 via the charge / discharge control circuit 83 to charge the battery 84. The charge / discharge control circuit 83 controls the charge when the battery 84 is charged by the output from the power receiving circuit 82, and controls the discharge when the vehicle body 9 which is a load is operated by the battery 84. Is. The battery 84 is a rechargeable secondary battery (for example, a lithium ion battery, a nickel hydrogen battery, etc.) that can be repeatedly used by charging after being discharged.

In the non-contact power feeding device according to the present embodiment, the transmission coil unit according to the present invention described above can be used for the power transmission coil 74. As a result, since a transmission coil unit that can be manufactured at low cost by reducing high frequency loss due to the skin effect and proximity effect is used, it is possible to provide a non-contact power feeding device with high transmission efficiency and low cost.

Further, the transmission coil unit according to the present invention described above may also be used for the power receiving coil 81. Further, it is possible to provide a low-cost non-contact power feeding device having high transmission efficiency.

The non-contact power feeding device according to the present invention is not limited to that for automobiles. It may be used to power an electronic device such as a mobile phone, a smartphone, or a tablet. Further, the transmission coil unit according to the present invention may also be applied to an inductive heating device or the like. Further, the transmission coil unit according to the present invention is not limited to use in an electromagnetic induction type non-contact power feeding device. It may also be applied to a magnetic field resonance type non-contact power feeding device.

Hereinafter, simulations and experiments when the transmission coil unit according to the present invention is carried out and applied, and the results thereof will be described. However, the present invention is not limited to the application examples described here.

<1. Simulation analysis model>
Before explaining an application example by simulation of the transmission coil unit according to the present invention, first, a simulation model for analyzing the characteristics (AC resistance, inductance, Q value, coupling coefficient k, transmission efficiency η) of the coil components will be described. To do.

As the analysis software for the simulation, the electromagnetic field analysis software ANSYS Maxwell (manufactured by Ansys) was used. Table 1 summarizes the analysis conditions.

FIG. 12 is a diagram (plan view) for explaining the calculation model of the coil. The coil is assumed to be an aluminum material having a resistivity of 2.78 × ^10-8 Ωm. It is a flat coil with 6 turns. The inner and outer diameters of the coil are φ205 mm and φ350 mm, respectively. The frequency of the alternating current that energizes the coil is 85 kHz.

<2. Example by calculation of power transmission coil>
The coil characteristics (AC resistance, inductance, Q value) when the transmission coil unit of the present invention is used for the transmission coil are calculated.

(Example 1)
FIG. 13 is a cross-sectional dimensional view of the coil 2 and the magnetic shield 3 of the transmission coil unit of the first embodiment. Corresponds to the cross-sectional view taken along the line AA'in FIG.

As shown in FIG. 13, the cross-sectional shape of the coil conductor 21 of each winding is a rectangular shape of 9.2 × 2 mm, and the coil conductor 21 has 6 turns. The distance pitch between the neighbors of the coil conductor 21 (the distance between the centers of the coil conductors next to each other) is 12.5 mm, the closest distance between the coil conductor 21 and the magnetic shield is 5 mm, and the center of the coil conductor 21 on the innermost circumference and the spiral shape. The distance from the center of the coil is 107.5 mm, and the distance between the center of the outermost coil conductor 21 and the center of the spiral coil is 170 mm. The angle of the rectangular shape with respect to the magnetic shield 3 in the longitudinal direction is 90 °, 45 °, 0 °, 0 °, -45 °, -90 from the inner circumference to the outer circumference of the coil 2 along the flow of the generated magnetic flux lines. It changes gradually with °. That is, the coil cross-sectional shape of the coil conductor 21 has a shape portion that follows the flow of magnetic flux lines.

Table 2 summarizes the calculated coil characteristics (AC resistance R, inductance L, Q value).

(Example 2)
FIG. 14 is a cross-sectional dimensional view of the coil 2 and the magnetic shield 3 of the transmission coil unit of the second embodiment. Corresponds to the cross-sectional view taken along the line AA'in FIG.

As shown in FIG. 14, the cross-sectional shape of the coil conductor 21 of each winding is the same U-shape from the inner peripheral portion 22 to the outer peripheral portion 24 of the coil. Each dimension of the U-shape is as shown in the figure. The U-shape is symmetrical, and the coil conductor 21 has 6 turns. Spacing pitch between adjacent coil conductors 21 (distance between the centers of adjacent coil conductors), the closest distance between the coil conductors 21 and the magnetic shield, and the distance between the center of the innermost coil conductor 21 and the center of the spiral coil. The distances between the center of the outermost coil conductor 21 and the center of the spiral coil are 12.5 mm, 5 mm, 107.5 mm, and 170 mm, respectively, as in FIG.

The inner peripheral portion 22 of the coil 2 has an L-shaped portion on the inner peripheral side of the U-shape, the outer peripheral portion 24 has an L-shaped portion on the outer peripheral side of the U-shape, and the central portion 23 has a U-shaped portion. The flat portion of is corresponding to the shape portion along the flow of the magnetic flux line.

Table 2 summarizes the calculated coil characteristics (AC resistance R, inductance L, Q value).

(Example 3)
FIG. 15 is a cross-sectional dimensional view of the coil 2 and the magnetic shield 3 of the transmission coil unit of the third embodiment. Corresponds to the cross-sectional view taken along the line AA'in FIG.

The cross-sectional shape of the coil conductor 21 of each winding is U-shaped, but as shown in FIG. 15, the aspect ratio of the shape from the inner peripheral portion 22 to the outer peripheral portion 24 (side length with respect to the upper surface width of the U-shaped shape). Ratio) is changing step by step. Each dimension of the U-shape is as shown in the figure. The U-shape is symmetrical, and the six-roll coil conductors 21 are arranged symmetrically around the central portion 23. Spacing pitch between adjacent coil conductors 21 (distance between the centers of adjacent coil conductors), the closest distance between the coil conductors 21 and the magnetic shield, and the distance between the center of the innermost coil conductor 21 and the center of the spiral coil. The distances between the center of the outermost coil conductor 21 and the center of the spiral coil are 12.5 mm, 5 mm, 107.5 mm, and 170 mm, respectively, as in FIG.

In the third embodiment, the inner peripheral portion 22 and the outer peripheral portion 24 of the coil 2 have a substantially rectangular shape, and have a shape portion whose longitudinal direction is perpendicular to the magnetic shield surface and follows the flow of magnetic flux lines. Further, the central portion 23 of the coil 2 also has a shape portion whose longitudinal direction is substantially parallel to the magnetic shield surface and which follows the flow of the magnetic flux line 5. Then, a coil is formed between the inner peripheral portion 22 and the central portion 23 and between the central portion 23 and the outer peripheral portion 24 so that the left and right L-shaped portions of the U-shape correspond to the shape portions along the flow of the magnetic flux lines. The cross-sectional shape is changing step by step.

Table 2 summarizes the calculated coil characteristics (AC resistance R, inductance L, Q value).

(Comparative Example 1)
FIG. 16 is a cross-sectional dimensional view of the coil 2 and the magnetic shield 3 of the transmission coil unit of Comparative Example 1. Corresponds to the cross-sectional view taken along the line AA'in FIG.

As shown in FIG. 16, the cross-sectional shape of the coil conductor 21 of each winding is a rectangular shape of 9.2 × 2 mm, and all of them are arranged parallel to the magnetic shield surface of the magnetic shield 3. The coil conductor 21 has 6 turns. Spacing pitch between adjacent coil conductors 21 (distance between the centers of adjacent coil conductors), the closest distance between the coil conductors 21 and the magnetic shield, and the distance between the center of the innermost coil conductor 21 and the center of the spiral coil. The distances between the center of the outermost coil conductor 21 and the center of the spiral coil are 12.5 mm, 5 mm, 107.5 mm, and 170 mm, respectively, as in FIG.

Table 2 summarizes the calculated coil characteristics (AC resistance R, inductance L, Q value).

(Example 4)
The coil of the transmission coil unit of the fourth embodiment is a coil of the first embodiment shown in FIG. 13 in which a magnetic layer is formed on the entire surface of the coil conductor of each winding as shown in FIG. The film thickness of the magnetic layer is 0.2 mm.

Table 2 summarizes the calculated coil characteristics (AC resistance R, inductance L, Q value).

(Examples 5 to 7)
The transmission coil unit of the fifth embodiment has magnetic layers on the upper surface of the U-shaped coil conductor and the surfaces of both left and right sides of the coil of the second embodiment shown in FIG. 14, as shown in FIG. 6 (A). It is formed. The film thickness of the magnetic layer is 0.2 mm.

The transmission coil unit of the sixth embodiment has the coil of the second embodiment shown in FIG. 14 on the U-shaped upper surface of the coil conductor, the left and right side surfaces, and the magnetic shield surface as shown in FIG. 8 (B). A magnetic layer is formed on the surface of the facing surface. The film thickness of the magnetic layer is 0.2 mm.

The transmission coil unit of the seventh embodiment faces the U-shaped upper surface of the coil conductor, the left and right side surfaces, and the magnetic shield surface of the coil of the second embodiment shown in FIG. 14, as shown in FIG. 8 (C). In addition to the magnetic layer on the surface of the surface to be formed, a magnetic layer is also formed on the inner surface of the recess. The film thickness of the magnetic layer is 0.2 mm.

Table 2 summarizes the coil characteristics (AC resistance R, inductance L, Q value) obtained by calculation for Examples 5 to 7.

<3. Example by calculation of power transmission coil and power reception coil>
Coil characteristics (coupling coefficient k and transmission efficiency η) when the transmission coil unit according to the present invention is used as a transmission coil and a power receiving coil, and both coils face each other at a distance of 150 mm (transmission distance) and face each other. To calculate. The coupling coefficient k is a number representing the degree of coupling between the power transmitting coil and the power receiving coil constituting the transformer. The transmission efficiency η can be obtained by the product of the coupling coefficient k and the Q value.

(Examples 8 to 11)
The eighth embodiment is a case where the transmission coil unit of the first embodiment shown in FIG. 13 is used as a power transmission coil and a power reception coil.

The ninth embodiment is a case where the transmission coil unit of the second embodiment shown in FIG. 14 is used as a power transmission coil and a power reception coil.

The tenth embodiment is a case where the transmission coil unit with a magnetic layer of the fourth embodiment is used as a power transmission coil and a power reception coil.

The eleventh embodiment is a case where the transmission coil unit with a magnetic layer of the fifth embodiment is used as a power transmission coil and a power reception coil.

Table 2 summarizes the coil characteristics (coupling coefficient k and transmission efficiency η) obtained by calculation for Examples 8 to 11.

(Comparative Example 2)
Comparative Example 2 is a case where the transmission coil unit of Comparative Example 1 shown in FIG. 16 is used as a power transmission coil and a power reception coil.

Table 2 summarizes the calculated coil characteristics (coupling coefficient k and transmission efficiency η).

As is clear from Table 2, in Examples 1 to 3, the AC resistance is reduced, the Q value is increased, and the high frequency loss is reduced as compared with Comparative Example 1. Further, in Examples 4 to 5 in which the magnetic layer is formed on the surface of the coil conductor, the AC resistance is further reduced, the Q value is increased, and the high frequency loss is very small.

Further, from Table 2, it can be seen that higher transmission efficiency η can be obtained for Examples 8 and 9 and Examples 10 and 11 as compared with Comparative Example 2.

Therefore, by using the transmission coil unit according to the present invention as a power transmission coil, and as a power transmission coil and a power reception coil, it is possible to suppress an increase in AC resistance and realize non-contact power supply with high transmission efficiency.

(Example 12)
In this embodiment, an experiment and an experimental result using a prototype of the transmission coil unit according to the fifth embodiment will be described. First, the prototype coil 2 has the shape shown in FIG. 7 (fifth embodiment), and has external dimensions of 250 × 250 mm. The material is aluminum. As shown in FIG. 8D, a coil having a magnetic layer on the upper surface including an edge and a coil not provided with a magnetic layer were prototyped. The detailed dimensions of the coil conductor 21 portion are shown in FIG. The non-magnetic insulator 41 has dimensions of 280 x 280 mm, a groove depth for embedding the coil of 1 mm (not shown), and is made of polycarbonate. The size of the magnetic shield 3 (not shown) is 260 mm × 260 mm, and is provided at a position 5 mm away from the coil conductor 21 with the non-magnetic insulator 41 interposed therebetween. The material is ferrite.

The results of measuring the coil characteristics (AC resistance, Q value, inductance) of the transmission coil unit of the present embodiment configured as described above using an impedance analyzer are shown in FIGS. 18 (a), (b), and (c). Each is shown in. In the figure, "AP" represents an aluminum coil without the magnetic layer, and "MCP" represents an aluminum coil with the magnetic layer. Further, the characteristic values at 85 kHz are shown in Table 3.


Compared with the simulation results in Table 2, both the AC resistance and the inductance are larger. For example, comparing aluminum conductors with a U-shaped cross section (without a magnetic layer), Table 2 (Example 2) has an AC resistance of 74.17 mΩ and an inductance of 22.75 μH, whereas in this example, the AC resistance is 287 mΩ. The inductance is 34.9 μH. Comparing the transmission efficiencies, it was 94.0% in Table 2 (Example 9), but it was slightly lower at 91.4% in this example.

One of the causes of the difference between this embodiment (measured value) and Table 2 (calculated value) is considered to be the shape of the coil. That is, in Table 2, the calculation was performed using a circular model having a diameter of 350 mm and 6 turns, whereas the coil used in this embodiment has a side of 250 mm and a rectangular shape of 10 turns. The magnetic flux density is higher and the AC resistance tends to be higher. On the other hand, the AC resistance reduction effect due to the provision of the magnetic layer was 1.2% (94.0% to 95.2%) in the calculation (Table 2), whereas it was 1.6 in this example. % (91.4% to 93.0%), and the improvement effect becomes more remarkable.

As a comparative example, Table 3 also shows the actual measurement results of the same shape (250 mm × 250 mm rectangle) using a copper litz wire (2100 stranded wire). The AC resistance is as low as 41.2 mΩ. The volume resistivity of aluminum is about 60% higher than that of copper, but even if this is taken into consideration, the AC resistance of this embodiment is more than three times that of litz wire. However, if this difference is due to the difference in the suppression ability with respect to the skin effect, a coil conductor 21 having a U-shaped cross section is formed by laminating several layers of magnetic thin plates (for example, 0.2 mm thick). It is presumed that this difference can be reduced with some measures such as.

The transmission coil unit and the non-contact power feeding device according to the present invention can be used in the fields of electronic devices such as automobiles and mobile phones, and inductive heating devices.

1 Transmission coil unit 2 Coil 21 Coil conductor 22 Inner circumference 23 Central part 24 Outer part 25 Top surface width 26 Side length 3 Magnetic shield 4 Electric shield 41 Non-magnetic insulator 5 Magnetic field line 6 Magnetic layer 7 Transmission device 71 Power supply 72 Rectifier circuit 73 Transmission circuit 74 Transmission coil 8 Power receiving device 81 Power receiving coil 82 Power receiving circuit 83 Charging / discharging control circuit 84 Battery 9 Automobile body

Claims (11)

A non-contact power supply transmission coil unit including a coil wound in a spiral shape and a magnetic shield arranged so as to face the coil surface of the coil at a predetermined distance.
A non-contact power feeding transmission coil unit having a coil cross-sectional shape in the winding direction of each winding coil conductor along a magnetic flux line generated when a current flows through the coil. The coil cross-sectional shape is rectangular
The longitudinal direction of the rectangular shape is substantially perpendicular to the magnetic shield surface of the magnetic shield at the inner peripheral portion and the outer peripheral portion of the coil, and is substantially perpendicular to the magnetic shield surface at the central portion between the inner peripheral portion and the outer peripheral portion. Parallel and
A claim characterized in that the longitudinal angle of the rectangular shape with respect to the magnetic shield surface changes stepwise between the inner peripheral portion and the central portion and between the central portion and the outer peripheral portion. Item 2. The non-contact power feeding transmission coil unit according to item 1. The coil cross-sectional shape is U-shaped,
The non-contact power supply transmission coil unit according to claim 1, wherein the U-shaped recess faces the magnetic shield surface. It has a rectangular planar shape, is provided with a non-magnetic insulator in which a spiral groove having a straight portion at a side portion and an arc portion at a corner portion is formed, and the coil is continuously provided in the groove. The non-contact power supply transmission coil unit according to claim 3. The transmission coil unit for non-contact power feeding according to claim 4, wherein the non-magnetic insulator is made of a resin having a thermal conductivity of 1 W / (mK) or more. The non-contact power feeding transmission coil unit according to claim 4, wherein at least a side surface of the coil conductor is in direct or indirect contact with the non-magnetic insulator. The ratio of the side length to the upper surface width of the U-shape is the maximum in the inner peripheral portion and the outer peripheral portion of the coil, the minimum in the central portion between the inner peripheral portion and the outer peripheral portion, and the said. The one according to any one of claims 3 to 6, wherein the ratio changes stepwise between the inner peripheral portion and the central portion and between the central portion and the outer peripheral portion. Transmission coil unit for non-contact power supply. The invention according to any one of claims 1 to 7, wherein a magnetic layer is formed on at least a surface and a side surface of the coil cross-sectional shape opposite to the surface facing the magnetic shield surface. Transmission coil unit for non-contact power supply. Any one of claims 1 to 7, which comprises a step of grooving the metal flat plate in a spiral shape by laser processing or press working, and a step of deforming the grooved metal flat plate by press working. The method for manufacturing a non-contact power supply transmission coil unit according to the section. A step of grooving a metal flat plate in a spiral shape by laser processing or press working, a step of deforming the grooved metal flat plate by press working, and a magnetic layer on the surface of the grooved metal flat plate. The method for manufacturing a non-contact power supply transmission coil unit according to claim 8, further comprising a step of forming. A non-contact power feeding device according to any one of claims 1 to 8, wherein the non-contact power feeding transmission coil unit is used as a power transmission coil, or as a power transmission coil and a power receiving coil.