JP6684579B2 - Contactless power supply system - Google Patents

Description

  The present invention relates to a contactless power supply system, and is particularly suitable for a contactless power supply system for a plug-in hybrid vehicle or an electric vehicle that performs contactless power supply between a primary coil on the ground side and a secondary coil on the vehicle upper side. Regarding technology.

  In plug-in hybrid vehicles (PHEV) and electric vehicles (EV) that are battery-charged with external power, wireless power feeding (contactless power feeding) is used because of the hassle of connecting charging cables, stains on clothes, and anxiety when it rains. ) Is growing in need.

  Non-contact power feeding includes an electromagnetic induction type that uses electromagnetic induction between a primary coil on the ground side and a secondary coil on the vehicle side, and a magnetic field resonance type that uses magnetic field resonance. In either method, a large alternating magnetic field is generated from the power transmission coil, and there is a concern that the magnetic field may affect the human body. In the international standardization of the contactless power supply system for automobiles, it is expected that the alternating magnetic field outside the vehicle will be required to be 27 μT or less, which is the standard guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP).

  2. Description of the Related Art Conventionally, in a non-contact power feeding system for an automobile, the generation of a leakage magnetic field from the power transmission coil is reduced by surrounding the power transmission coil with a magnetic material (see, for example, Patent Document 1).

JP, 2014-166070, A

  There are helical coil and spiral coil as the types of coils used in the non-contact power feeding system, but in the international standardization of the non-contact power feeding system for automobiles, it was decided to use the spiral coil as the primary coil and the secondary coil. . Since the spiral coil has a smaller leakage magnetic field than the helical coil, it is easy to satisfy the above criteria. However, if the transmission power is increased by rapid charging or the like, the leakage magnetic field becomes large, and there is a risk that the above criteria will not be satisfied. In addition, since the power transmission coil on the ground side is hidden by the vehicle body during contactless power supply, a person can be separated from the power transmission coil by a certain distance if the vehicle body is large to some extent like a normal car, but in the case of a small car such as a commuter vehicle. Since the vehicle body is small, it may not be possible to keep a person away from the power transmission coil by a certain distance or more, and the above criteria may not be satisfied.

  In view of the above problems, it is an object of the present invention to reduce a leakage magnetic field to the outside of a vehicle while maintaining good power transmission efficiency in a contactless power supply system for an automobile.

In a contactless power feeding system according to one aspect of the present invention, a first coil installed on the ground and a second coil installed on a lower surface of a vehicle body face each other, and the first coil and the second coil are opposed to each other. A non-contact power feeding system that performs non-contact power feeding between two coils, wherein the first coil and the second coil are both spiral coils, and a power transmitting coil that transmits power among the first coil and the second coil A flange is provided upright on both sides of the power transmission coil in the vehicle width direction so that the entire power transmission coil is hidden in a side view from the vehicle width direction, and the non-conductive magnetic thin film is formed on the surface of the flange on the power transmission coil side. There are formed, the power transmission coil is mounted on the coil core formed of magnetic material, coil core is mounted on an iron plate of the flange is provided, in a portion of the coil core is non-conductive magnetic thin film While not kicked, in the region between the flange and the coil core in the iron plate, non-conductive magnetic thin film is formed, is that.

  According to this, the leakage magnetic field from the power transmission coil is reduced by providing the flange around the power transmission coil, and the non-conductive magnetic thin film is formed on the surface (inner peripheral surface) of the flange on the power transmission coil side. , The power transmission efficiency between the first coil and the second coil can be kept good.

  Preferably, the flange is erected at a position about 75 mm away from the outer circumference of the power transmission coil. Further, the relative magnetic permeability of the non-conductive magnetic thin film is set to about 50. Further, the protrusion height of the flange is made equal to the height of the surface of the power transmission coil.

  According to these, both reduction of the leakage magnetic field and improvement of the power transmission efficiency can be realized in a balanced manner.

  The flange may be an annular flange that surrounds the outer circumference of the power transmission coil.

  According to this, it is possible to reduce the leakage magnetic field in all side directions of the power transmission coil.

  The non-conductive magnetic thin film may be a coating film formed by applying a magnetic paint.

  According to this, the non-conductive magnetic thin film can be formed by a simple method such as applying a magnetic paint to the inner peripheral surface of the flange.

  According to the present invention, it is possible to reduce the leakage magnetic field to the outside of the vehicle while maintaining good power transmission efficiency in the non-contact power supply system for automobiles.

Schematic of the non-contact electric power feeding system which concerns on one Embodiment of this invention. The top view and sectional drawing of the power transmission coil which concerns on an example. The top view and sectional drawing of the receiving coil which concern on an example. Graph of distance from coil center where magnetic flux density by material used for flange is below guideline standard Graph of power transfer efficiency by material used for flange The figure which shows an example of the flange of the power transmission coil side The figure which shows another example of the flange of the power transmission coil side The figure which shows another example of the flange of the power transmission coil side. Graph showing the relationship between the relative permeability of the magnetic paint on the flange and the distance from the coil center where the magnetic flux density is below the guideline standard. Graph showing the relationship between the relative permeability of the magnetic paint on the flange and the power transmission efficiency Graph showing the relationship between the diameter of the flange and the distance from the coil center where the magnetic flux density is below the guideline standard. Graph showing the relationship between flange diameter and power transmission efficiency

  Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed description of well-known matters and repeated description of substantially the same configuration may be omitted. This is for avoiding unnecessary redundancy in the following description and for facilitating understanding by those skilled in the art.

  It should be noted that the inventors provide the accompanying drawings and the following description for those skilled in the art to fully understand the present invention, and are intended to limit the subject matter described in the claims by these. is not. Further, the dimensions, thicknesses, detailed shapes of details, and the like of each member depicted in the drawings may be different from the actual ones.

  FIG. 1 schematically shows a contactless power feeding system according to an embodiment of the present invention. For example, the contactless power supply system according to the present embodiment is a magnetic field resonance type contactless power supply system that wirelessly charges a battery 30 of a vehicle 100 such as a plug-in hybrid vehicle or an electric vehicle.

  In the contactless power feeding system according to the present embodiment, the ground device 200 and the power transmission unit 60 are installed on the ground. The vehicle 100 and the ground device 200 can communicate with each other by radio 300. The automobile 100 determines the amount of charge of the battery 30 and requests the ground device 200 to start / stop power supply via the radio 300 as appropriate. The ground device 200 controls supply / stop of electric energy to the vehicle 100 according to a request from the vehicle 100.

  When supplying electric energy to the vehicle 100, the ground apparatus 200 generates a high frequency current of 3 kW class in the 85 kHz band (81.38 kHz to 90 kHz) from commercial power (AC power supply). The high frequency current generated by the ground device 200 is passed through the cable 201 to the power transmission unit 60. An unillustrated power transmission coil (primary coil) is housed in the power transmission unit 60, and a strong magnetic field is generated in the power transmission unit 60 by supplying a high frequency current to the power transmission coil.

  On the other hand, in the automobile 100, the power receiving unit 10 is installed on the lower surface of the vehicle body. When charging the battery 30, the vehicle 100 is moved so that the power receiving unit 10 is located at a position vertically opposed to the power transmission unit 60. The gap between the power receiving unit 10 and the power transmitting unit 60 is 100 to 160 mm.

  The power receiving unit 10 accommodates a resonance circuit including a power receiving coil (secondary coil) and a capacitor (not shown). When the power receiving unit is exposed to the magnetic field generated by the power transmission unit 60, the resonance circuit resonates. A high frequency current is generated in the power receiving unit 10. The high frequency current generated in the power receiving unit 10 is converted into a direct current by the rectifier 20 and charged in the battery 30. As described above, in the system according to the present embodiment, electric energy is wirelessly supplied from the ground apparatus 200 to the automobile 100 by magnetic field resonance.

  An inverter 40 is connected to the battery 30. When the vehicle 100 is driven, the inverter 40 converts the direct current stored in the battery 30 into an alternating current to drive the electric motor 50 that is the power source of the vehicle 100.

  FIG. 2 is a plan view and a cross-sectional view of a power transmission coil according to an example. A power transmission coil 61 is housed in the power transmission unit 60. The power transmission coil 61 is a spiral coil formed by winding an insulated coated electric wire 62 having a diameter of 5.4 mm in a circular spiral shape in two stages and eight turns, and has an outer diameter of 350 mm and an inner diameter of 260 mm. The power transmission coil 61 is mounted on a disk-shaped coil core 63 formed of a magnetic material such as ferrite. The coil core 63 has a diameter of 400 mm. The coil core 63 is attached to the iron plate 64.

  An annular flange made of an iron plate having a thickness of several mm so as to surround the outer periphery of the power transmission coil 61 at a position about 75 mm away from the outer periphery of the power transmission coil 61 in order to reduce the leakage magnetic field in the side direction of the power transmission coil 61. 65 is provided. The diameter of the flange 65 is 500 mm. The flange 65 may be integrally formed with the iron plate 64, or may be attached to the iron plate 64 by welding, screwing, or the like.

  From the viewpoint of reducing the leakage magnetic field in the side direction of the power transmission coil 61, the protrusion height of the flange 65 is set to a height such that the entire power transmission coil 61 is hidden in a side view. Here, the power transmission efficiency can be increased and the leakage magnetic field can be suppressed by shortening the distance between the power transmitting and receiving coils as much as possible, and thus the member protruding from the surface of the power transmitting coil 61 in the power transmitting unit 60. It is desirable not to provide. Therefore, it is appropriate to set the protrusion height of the flange 65 to about the height of the surface of the power transmission coil 61 even if the protrusion height is increased to the maximum.

  A magnetic coating film 66 is formed on the inner peripheral surface of the flange 65. The magnetic coating film 66 can be formed by applying a coating material (magnetic coating material) containing a magnetic material such as ferrite in the form of fine particles or magnetic material pieces to a thickness of several mm. The magnetic coating film 66 has characteristics of high magnetic permeability and high electric resistance, and can absorb magnetic flux and suppress loss due to eddy current. That is, by forming the magnetic coating film 66 on the inner peripheral surface of the flange 65, it is possible to suppress the generation of eddy currents in the flange 65 and maintain good power transmission efficiency.

  The magnetic coating film 66 may be formed on the surface of the iron plate 64 that is not covered with the coil core 63. As a result, generation of eddy currents in the iron plate 64 can be suppressed and power transmission efficiency can be improved.

  FIG. 3 is a plan view and a cross-sectional view of a power receiving coil according to an example. A power receiving coil 11 is housed in the power receiving unit 10. The power receiving coil 11 is a spiral coil formed by winding an insulating covered electric wire 12 having a diameter of 5.4 mm in a circular spiral shape eight times in one step, and has an outer diameter of 350 mm and an inner diameter of 260 mm. The power receiving coil 11 is mounted on a disk-shaped coil core 13 made of a magnetic material such as ferrite. The diameter of the coil core 13 is 400 mm. The coil core 13 is attached to an iron plate 14 that forms an undercover on the lower surface of the automobile 100.

  Basically, in the contactless power feeding system, electric energy is wirelessly supplied from the ground apparatus 200 to the vehicle 100, but conversely, electric power generated by the vehicle 100 may be wirelessly transmitted to the ground apparatus 200. In this case, the roles of the power receiving coil 11 and the power transmitting coil 61 are switched, the power receiving coil 11 functions as a power transmitting coil, and the power transmitting coil 61 functions as a power receiving coil. Therefore, it is necessary to reduce the leakage magnetic field in the lateral direction of the power receiving coil 11 as well.

  An annular flange made of an iron plate having a thickness of several mm so as to surround the outer periphery of the power receiving coil 11 at a position about 75 mm away from the outer periphery of the power receiving coil 11 in order to reduce the leakage magnetic field in the lateral direction of the power receiving coil 11. 15 are provided. The diameter of the flange 15 is 500 mm. The flange 15 may be integrally formed with the iron plate 14, or may be attached to the iron plate 14 by welding, screwing, or the like.

  From the viewpoint of reducing the leakage magnetic field in the lateral direction of the power receiving coil 11, the protruding height of the flange 15 is set to a height such that the entire power receiving coil 11 is hidden in a side view. Here, the power transmission efficiency can be increased and the leakage magnetic field can be suppressed by making the distance between the power transmitting and receiving coils as short as possible. Therefore, a member protruding from the surface of the power receiving coil 11 in the power receiving unit 10. It is desirable not to provide. Therefore, even if the protrusion height of the flange 15 is maximized, it is appropriate that the height of the surface of the power receiving coil 11 is approximately the same.

  A magnetic coating film 16 similar to the magnetic coating film 66 (FIG. 2) is formed on the inner peripheral surface of the flange 15. As a result, generation of eddy currents in the flange 15 can be suppressed, and good power transmission efficiency can be maintained. The magnetic coating film 16 may be formed on the surface of the iron plate 14 that is not covered with the coil core 13. As a result, generation of eddy currents in the iron plate 14 can be suppressed and power transmission efficiency can be improved.

  The magnetic coating film 16 and the magnetic coating film 66 are examples of the "non-conductive magnetic thin film" described in the claims. A magnetic film or the like may be attached instead of applying the magnetic paint. Alternatively, the magnetic thin film may be formed by a method such as plating or vapor deposition.

  Further, since the magnetic coating film 16 is exposed to the external environment, it is desirable that the magnetic coating material is subjected to anticorrosion treatment, or that the surface of the magnetic coating film 16 is subjected to anticorrosion treatment after applying the magnetic coating material.

  The shape of the power receiving coil 11 does not have to be the same as the shape of the power transmitting coil 61. For example, the outer diameter and the inner diameter of the power receiving coil 11 may be reduced by 100 mm from the above (outer diameter 250 mm, inner diameter 160 mm). By reducing the size of the power receiving coil 11 in this way, the cost of the power receiving unit 10 can be reduced, and the work of mounting the power receiving unit 10 becomes easy.

  Neither the power transmission coil 61 nor the power receiving coil 11 need be circular. For example, the power transmission coil 61 and / or the power reception coil 11 may have an elliptical or elliptical shape that is long in the vehicle width direction.

  Next, the optimum selection of the material used for the flange 15 and the flange 65 will be described. The simulation was performed under the condition that the power transmitting coil 61 of FIG. 2 and the power receiving coil 11 of FIG. 3 were opposed to each other with a distance of 150 mm and a high frequency current of 3 kW in the 85 kHz band was applied to the power transmitting coil 61. FIG. 4 is a graph of the distance from the coil center where the magnetic flux density for each material used for the flange is equal to or less than the guideline standard (27 μT). The coil center here is the center of the power transmission coil 61. It can be said that the shorter the distance from the coil center, the more the leakage magnetic field can be reduced. FIG. 5 is a graph of power transmission efficiency for each material used for the flange. It should be noted that each of the graphs includes a case without a flange as a comparative example.

In the graphs of FIGS. 4 and 5,
(1) “Without flange and magnetic coating” means that the magnetic coating is not formed on the surfaces of the iron plate 14 and the iron plate 64 without providing the flange 15 and the flange 65.
(2) "With flange without magnetic coating" means that the magnetic coating is formed with a thickness of 1 mm on the surfaces of the iron plate 14 and the iron plate 64 without providing the flange 15 and the flange 65.
(3) "Iron (without magnetic coating film)" represents a case where the iron flange 15 and the flange 65 are provided and the magnetic coating film is not formed.
(4) "Aluminum (without magnetic coating film)" represents a case where the flange 15 and the flange 65 made of aluminum are provided and the magnetic coating film is not formed.
(5) "Ferrite (without magnetic coating film)" represents a case where the flange 15 and the flange 65 made of ferrite are provided and the magnetic coating film is not formed.
(6) "Iron + magnetic coating film (relative magnetic permeability 100)" is a magnetic coating film having a relative magnetic permeability of 100 on the inner peripheral surface of the iron flange 15 and the flange 65 and the surfaces of the iron plate 14 and the iron plate 64. 16 and the magnetic coating film 66 are formed with a thickness of 1 mm.
(7) “Iron + magnetic coating film (relative magnetic permeability 250)” is a magnetic coating film having a relative magnetic permeability of 250 provided with iron flanges 15 and 65, and the inner peripheral surfaces thereof and the surfaces of the iron plates 14 and 64. 16 and the magnetic coating film 66 are formed with a thickness of 1 mm.

  As can be seen from the graph of FIG. 4, the above (3), (4), (6), and (7) are good for reducing the leakage magnetic field, and the magnetic flux density is set to the guideline standard or less at a position 400 mm or more away from the coil center. be able to. As a result, the magnetic flux density leaking to the outside of the vehicle can be kept below the general guideline standard even for a small vehicle with a short vehicle width. Further, even if the distance from the center of the coil at which the transmission power increases and the magnetic flux density becomes equal to or lower than the guideline standard extends a little, it can be accommodated within the vehicle width. On the other hand, regarding the graph of FIG. 5 and the power transmission efficiency, the above (2), (4), (5), (6) and (7) are good. From this, it is the above (4), (6) and (7) that satisfy both the reduction of the leakage magnetic field and the power transmission efficiency. Here, in consideration of the ease of attachment to the iron plate 14 and the iron plate 64 and the integral moldability, the flange 15 and the flange 65 are preferably made of iron rather than aluminum, and the condition (6) above is further satisfied. (7). That is, as described above, it can be said that it is optimal to form the magnetic coating film 16 and the magnetic coating film 66 on the inner peripheral surfaces of the iron flange 15 and the flange 65.

  The shapes of the flange 65 and the flange 15 are not limited to annular shapes. FIG. 6A is a diagram showing an example of the flange 65 on the power transmission coil 61 side. For example, assuming a case where the power receiving unit 10 is installed between the left and right rear wheels of the vehicle rear portion of the automobile 100, the person in front of the vehicle can be kept away from the power transmission coil 61 by a certain distance or more because the vehicle length is in front of the vehicle. As shown in FIG. 6A, it is conceivable that the leakage magnetic field to the outside of the vehicle in front of the vehicle can be kept below the reference without forming the flange 65 in a U shape in plan view and providing the flange in the front portion of the vehicle. FIG. 6B is a diagram showing another example of the flange 65 on the power transmission coil 61 side. The flange 65 may be U-shaped in a plan view.

  FIG. 6C is a diagram showing yet another example of the flange 65 on the power transmission coil 61 side. If there is a ground device 200, a wall, or the like in the rear portion of the vehicle 100 that is supplying power, it is assumed that no person can enter the rear of the vehicle. Therefore, the flange of the rear portion of the vehicle is omitted, and as shown in FIG. 6C. The flange 65 may be provided only on the left and right portions of the vehicle. Further, the flange 65 may have an arc shape instead of a straight shape in a plan view.

  Although not shown, the flange 15 on the power receiving coil side can also have various shapes like the flange 65 described above.

  Next, the suitable relative magnetic permeability of the magnetic paint used for the magnetic coating film 16 and the magnetic coating film 66 will be described. The simulation was performed under the same conditions as above. FIG. 7 is a graph showing the relationship between the relative magnetic permeability of the magnetic paint on the flange and the distance from the coil center where the magnetic flux density is below the guideline standard. The coil center here is the center of the power transmission coil 61. It can be said that the shorter the distance from the coil center, the more the leakage magnetic field can be reduced. FIG. 8 is a graph showing the relationship between the relative magnetic permeability of the magnetic paint on the flange and the power transmission efficiency.

  As can be seen from these graphs, as the relative permeability of the magnetic paint increases from 0 to 50, the effect of reducing the leakage magnetic field decreases, but the power transmission efficiency sharply improves. When the relative permeability of the magnetic paint exceeds 50, the power transmission efficiency is not improved so much, and the effect of reducing the leakage magnetic field is not significantly deteriorated. From this, it can be said that the relative magnetic permeability of the magnetic paint used for the magnetic coating film 66 is preferably about 50. The same applies to the magnetic coating film 16 on the power receiving coil side.

  Next, suitable diameters (inner diameters) of the flange 15 and the flange 65 will be described. The simulation was performed under the same conditions as above. FIG. 9 is a graph showing the relationship between the diameter of the flange and the distance from the coil center where the magnetic flux density is below the guideline standard. The coil center here is the center of the power transmission coil 61. It can be said that the shorter the distance from the coil center, the more the leakage magnetic field can be reduced. FIG. 10 is a graph showing the relationship between the diameter of the flange and the power transmission efficiency.

  As can be seen from these graphs, it is sufficient for the power transmission efficiency that the diameter of the flange 65 is 500 mm or more, and for the reduction of the leakage magnetic field, it is sufficient that the diameter of the flange 65 is 500 mm or less. From this, it can be said that the diameter of the flange 65 is preferably about 500 mm. That is, as described above, it is preferable to provide the flange 65 at a position about 75 mm away from the outer circumference of the power transmission coil 61. The same applies to the flange 15 on the power receiving coil side.

  As described above, the embodiment has been described as an example of the technique of the present invention. To that end, the accompanying drawings and detailed description are provided.

  Therefore, among the components described in the accompanying drawings and the detailed description, not only the components essential for solving the problem but also the components not essential for solving the problem in order to exemplify the above technology Can also be included. Therefore, it should not be immediately recognized that these non-essential components are essential, because the non-essential components are described in the accompanying drawings and the detailed description.

  Further, since the above-described embodiments are for exemplifying the technique of the present invention, various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or the scope of equivalents thereof.

  For the sake of convenience, the technology in the present invention has been described above by taking the magnetic field resonance-type non-contact power supply system as an example, but the present invention is not limited to the magnetic field resonance-type non-contact power supply system, and an electromagnetic induction-type non-contact power supply system. It can also be applied to a power supply system.

11 Power receiving coil (second coil)
15 Flange 16 Magnetic coating (non-conductive magnetic thin film)
61 power transmission coil (first coil)
65 Flange 66 Magnetic coating (non-conductive magnetic thin film)

Claims (6)

A contactless power supply system in which a first coil installed on the ground and a second coil installed on a lower surface of a vehicle body face each other to perform contactless power supply between the first coil and the second coil. There
Each of the first coil and the second coil is a spiral coil,
Of the first coil and the second coil, for the power transmission coil that transmits power, both sides in the vehicle width direction with respect to the power transmission coil are hidden so that the entire power transmission coil is hidden in a side view from the vehicle width direction. The flange is erected on
A non-conductive magnetic thin film is formed on the surface of the flange on the power transmission coil side,
The power transmission coil is mounted on a coil core made of a magnetic material ,
The coil core is mounted on an iron plate provided with the flange,
While the non-conductive magnetic thin film is not provided in the coil core portion, the non-conductive magnetic thin film is formed in a region of the iron plate between the flange and the coil core. And a non-contact power supply system.   The contactless power feeding system according to claim 1, wherein the protrusion height of the flange is equal to the height of the surface of the power transmission coil.   The contactless power supply system according to claim 1, wherein the flange is an annular flange that surrounds the outer circumference of the power transmission coil.   The non-contact power feeding system according to claim 1, wherein the non-conductive magnetic thin film is a coating film formed by applying a magnetic paint. The flange has a U-shape or a U-shape in which both sides of the power transmission coil in the vehicle width direction and the vehicle rear side are surrounded and the vehicle front side of the power transmission coil is opened.
The contactless power feeding system according to claim 1. The contactless power supply system according to claim 1, wherein the flange is provided only on both sides of the power transmission coil in the vehicle width direction.

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