JP2017107896A - Non-contact power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce leakage magnetic field to the outside of a vehicle, while maintaining a good power transmission efficiency in a non-contact power supply system for vehicle.SOLUTION: In a non-contact power supply system performing non-contact power supply between a first coil (61) installed on the ground and a second coil (11) installed on the lower surface of the car body oppositely thereto, both first coil (61) and second coil (11) are spiral coils. In the power transmission coil for transmitting power, out of the first coil (61) and second coil (11), flanges (15, 65) are stood on the opposite sides in the vehicle width direction for the power transmission coil so that the whole power transmission coil is hidden, and non-conductive magnetic thin films (16, 66) are formed on the power transmission coil side surfaces of the flanges (15, 65).SELECTED DRAWING: Figure 2

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 charged by external power, wireless charging (non-contact charging) due to the troublesome work of connecting the charging cable, dirt on clothes, anxiety during rainy weather, etc. ) Needs are increasing.

  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 upper side, and a magnetic field resonance type that uses magnetic field resonance. In any system, a large alternating magnetic field is generated from the power transmission coil, and there is a concern about the influence of the magnetic field on the human body. In the international standardization of a contactless power supply system for automobiles, it is expected that the alternating magnetic field outside the vehicle is 27 μT or less, which is the standard guideline standard 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 a power transmission coil is reduced by surrounding the outer periphery of the power transmission coil with a magnetic material (for example, see Patent Document 1).

JP 2014-166070 A

  There are helical coils and spiral coils as the types of coils used in non-contact power supply systems, but it was decided to adopt spiral coils as primary and secondary coils in international standardization of non-contact power supply systems for automobiles. . Since the spiral coil has a smaller leakage magnetic field than the helical coil, it easily satisfies the above criteria. However, when the power transmission power is increased by rapid charging or the like, the leakage magnetic field becomes large, and there is a possibility that the above criteria may not be satisfied. In addition, since the ground-side power transmission coil is hidden by the vehicle body during non-contact power supply, people can be kept away from the power transmission coil by more than a certain distance as long as the vehicle body is large to a certain extent, but in the case of small vehicles such as commuters Since the vehicle body is small, there is a possibility that a person cannot be separated from the power transmission coil by a certain distance or more and the above-mentioned standard is not satisfied.

  In view of the above problems, an object of the present invention is 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 automobiles.

  In the non-contact power feeding system according to one aspect of the present invention, the first coil installed on the ground and the second coil installed on the lower surface of the vehicle body are opposed to each other. A non-contact power feeding system that performs non-contact power feeding between the first coil and the second coil, both of which are spiral coils, and a power transmission coil that transmits power among the first coil and the second coil The flange is erected on both sides in the vehicle width direction with respect to the power transmission coil so that the entire power transmission coil is hidden in a side view from the vehicle width direction. Is formed.

  According to this, the leakage magnetic field from the power transmission coil is reduced by providing a flange around the power transmission coil, and the non-conductive magnetic thin film is formed on the surface (inner peripheral surface) on the power transmission coil side of the flange. 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 periphery of the power transmission coil. Further, the relative permeability of the non-conductive magnetic thin film is set to about 50. Further, the protruding 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 power transmission efficiency can be realized in a balanced manner.

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

  According to this, the leakage magnetic field to all the side directions of a power transmission coil can be reduced.

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

  According to this, the nonconductive 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 Plan view and sectional view of power transmission coil according to an example Plan view and sectional view of power receiving coil according to an example Graph of distance from coil center where magnetic flux density by material used for flange is below guideline standard Graph of power transmission efficiency by material used for flange The figure which shows an example of the flange by the side of a power transmission coil The figure which shows another example of the flange by the side of a power transmission coil The figure which shows another example of the flange by the side of a power transmission coil 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 Graph showing the relationship between the relative permeability of magnetic paint on the flange and the power transmission efficiency Graph showing the relationship between the distance from the coil center where the flange diameter and magnetic flux density are below the guideline standard Graph showing the relationship between flange diameter and power transfer efficiency

  Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

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

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

  In the non-contact power feeding system according to the present embodiment, the ground device 200 and the power transmission unit 60 are installed on the ground. The automobile 100 and the ground device 200 can communicate with each other by the 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 appropriately through the radio 300. 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 automobile 100, the ground device 200 generates a 3 kW class high-frequency current in the 85 kHz band (81.38 k to 90 kHz) from commercial power (AC power supply). The high-frequency current generated by the ground device 200 is supplied to the power transmission unit 60 through the cable 201. A power transmission coil (primary coil) (not shown) is accommodated in the power transmission unit 60, and a strong magnetic field is generated in the power transmission unit 60 when a high-frequency current is passed through 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 automobile 100 is moved so that the power receiving unit 10 comes to a position facing the power transmission unit 60 in the vertical direction. The gap between the power reception unit 10 and the power transmission unit 60 is 100 to 160 mm.

  The power reception unit 10 accommodates a resonance circuit including a power reception coil (secondary coil) and a capacitor (not shown). The resonance circuit is resonated when the power reception coil is exposed to a magnetic field generated by the power transmission unit 60. 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 to the battery 30. Thus, in the system according to the present embodiment, electric energy is supplied wirelessly from the ground device 200 to the automobile 100 by magnetic field resonance.

  An inverter 40 is connected to the battery 30. When driving the automobile 100, the inverter 40 converts the direct current stored in the battery 30 into an alternating current and drives the electric motor 50 that is a power source of the automobile 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 accommodated in the power transmission unit 60. The power transmission coil 61 is a spiral coil in which an insulating coated electric wire 62 having a diameter of 5.4 mm is wound in two rounds and eight times in a circular spiral shape, 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 made of a magnetic material such as ferrite. The diameter of the coil core 63 is 400 mm. The coil core 63 is attached to the iron plate 64.

  In order to reduce the leakage magnetic field in the lateral direction of the power transmission coil 61, 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 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 or screwing.

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

  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 into fine particles or magnetic material pieces to a thickness of several millimeters. The magnetic coating film 66 has the characteristics of high magnetic permeability and high electrical 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 current in the flange 65 and to maintain good power transmission efficiency.

  The magnetic coating film 66 may also be formed on the surface of the iron plate 64 that is not covered with the coil core 63. Thereby, generation | occurrence | production of an eddy current can be suppressed in the iron plate 64, and electric 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 accommodated in the power receiving unit 10. The power receiving coil 11 is a spiral coil in which an insulation coated electric wire 12 having a diameter of 5.4 mm is wound in a circular spiral shape in eight steps, and has an outer diameter of 350 mm and an inner diameter of 260 mm. The 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 constituting an under cover on the lower surface of the automobile 100.

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

  In order to reduce the leakage magnetic field in the lateral direction of the power receiving coil 11, 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. 15 is 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 or screwing.

  From the viewpoint of reducing the leakage magnetic field in the side surface direction of the power receiving coil 11, the protruding height of the flange 15 is set such that the entire power receiving coil 11 is hidden in a side view. Here, when the distance between the power receiving and receiving coils is made as short as possible, the power transmission efficiency can be increased and the leakage magnetic field can be suppressed. Therefore, the member that protrudes 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 to make it approximately the height of the surface of the power receiving coil 11.

  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. Thereby, generation | occurrence | production of an eddy current in the flange 15 can be suppressed and electric power transmission efficiency can be kept favorable. The magnetic coating film 16 may also be formed on the surface of the iron plate 14 not covered with the coil core 13. Thereby, it can suppress that an eddy current generate | occur | produces in the iron plate 14, and can improve electric power transmission efficiency.

  The magnetic coating film 16 and the magnetic coating film 66 are examples of the “non-conductive magnetic thin film” recited 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.

  Furthermore, since the magnetic coating film 16 is exposed to the external environment, it is desirable to subject the magnetic coating material to a rust prevention treatment or to the surface of the magnetic coating film 16 after the magnetic coating material is applied.

  The shape of the power receiving coil 11 need not be the same as the shape of the power transmitting coil 61. For example, the outer diameter and inner diameter of the power receiving coil 11 may be made smaller by 100 mm than 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 mounting operation of the power receiving unit 10 is facilitated.

  Neither the power transmission coil 61 nor the power reception coil 11 need be circular. For example, the power transmission coil 61 and / or the power reception coil 11 may be oval or oval long in the vehicle width direction.

  Next, the optimal 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 transmission coil 61 of FIG. 2 and the power reception coil 11 of FIG. 3 are opposed to each other with a distance of 150 mm and a power of 3 kW in the 85 kHz band is applied to the power transmission 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 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 lower the leakage magnetic field. FIG. 5 is a graph of power transmission efficiency for each material used for the flange. Each graph includes a case without a flange as a comparative example.

In the graphs of FIG. 4 and FIG.
(1) “No flange-less magnetic coating film” represents a case where no magnetic coating film is 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 magnetic coating without flange” represents a case where the magnetic coating is formed on the surface of the iron plate 14 and the iron plate 64 with a thickness of 1 mm without providing the flange 15 and the flange 65.
(3) “Iron (no magnetic coating film)” represents the case where the iron flange 15 and the flange 65 are provided and the magnetic coating film is not formed.
(4) “Aluminum (no magnetic coating film)” represents the case where the aluminum flange 15 and the flange 65 are provided and no magnetic coating film is formed.
(5) “Ferrite (no magnetic coating film)” represents a case where the flange 15 and the flange 65 made of ferrite are provided and no magnetic coating film is formed.
(6) "Iron + magnetic coating film (relative magnetic permeability 100)" is provided with an iron flange 15 and flange 65, and a magnetic coating film having a relative permeability of 100 on the inner peripheral surface 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 provided with an iron flange 15 and flange 65, and a magnetic coating film having a relative permeability of 250 on the inner peripheral surface 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.

  As can be seen from the graph of FIG. 4, the above-mentioned (3), (4), (6), and (7) are good for reducing the leakage magnetic field, and the magnetic flux density is set below the guideline standard at a location 400 mm or more away from the coil center. be able to. Thereby, even if it is a small vehicle with a short vehicle width, the magnetic flux density which leaks outside the vehicle can be made below the general guideline standard. Moreover, even if the transmission power increases and the distance from the coil center where the magnetic flux density is below the guideline standard is slightly extended, it can be accommodated within the vehicle width. On the other hand, with respect to the graph of FIG. 5 and the power transmission efficiency, the above (2), (4), (5), (6), and (7) are good. Therefore, the above (4), (6) and (7) satisfy both the reduction of the leakage magnetic field and the power transmission efficiency. Here, considering the ease of attachment to the iron plate 14 and the iron plate 64 and the integral formability, it is preferable that the flange 15 and the flange 65 are made of iron instead of aluminum. (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 an annular shape. FIG. 6A is a diagram illustrating an example of the flange 65 on the power transmission coil 61 side. For example, assuming that the power receiving unit 10 is installed between the left and right rear wheels of the rear part of the automobile 100, since the vehicle front has a vehicle length, a person can be kept away from the power transmission coil 61 by a certain distance or more. As shown in FIG. 6A, it is considered that the leakage magnetic field to the outside of the vehicle in front of the vehicle can be less than the reference even if the flange 65 is U-shaped in plan view and the flange is not provided in the front portion of the vehicle. FIG. 6B is a diagram illustrating another example of the flange 65 on the power transmission coil 61 side. The flange 65 may be U-shaped in plan view.

  FIG. 6C is a diagram showing still another example of the flange 65 on the power transmission coil 61 side. If there is a ground device 200 or a wall or the like in the rear part of the vehicle 100 being fed, it is assumed that a person cannot enter the rear of the vehicle. Therefore, the flange in the rear part of the vehicle is also omitted, as shown in FIG. 6C. The flange 65 may be provided only on the left and right parts of the vehicle. Further, the flange 65 may be arcuate in addition to being linear in plan view.

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

  Next, the suitable relative magnetic permeability of the magnetic coating material 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 coating material 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 lower the leakage magnetic field. 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 coating material increases from 0 to about 50, the effect of reducing the leakage magnetic field is reduced, but the power transmission efficiency is rapidly improved. 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 deteriorated so much. From this, it can be said that the relative magnetic permeability of the magnetic coating 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, the suitable diameter (inner diameter) 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 lower the leakage magnetic field. 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 that the diameter of the flange 65 is 500 mm or more for the power transmission efficiency, and the diameter of the flange 65 may be 500 mm or less for reducing the leakage magnetic field. 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 separated from the outer periphery of the power transmission coil 61 by about 75 mm. The same applies to the flange 15 on the power receiving coil side.

  As described above, the embodiments have been described as examples of the technology in the present invention. For this purpose, the accompanying drawings and detailed description are provided.

  Accordingly, 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 illustrate the above technique. May also be included. Therefore, it should not be immediately recognized that these non-essential components are essential as those non-essential components are described in the accompanying drawings and detailed description.

  Moreover, since the above-mentioned embodiment is for demonstrating the technique in this invention, a various change, replacement, addition, abbreviation, etc. can be performed in a claim or its equivalent range.

  In the above, for the sake of convenience, the technology in the present invention has been described by taking a magnetic resonance type non-contact power feeding system as an example. However, the present invention is not limited to the magnetic field resonance type non-contact power feeding system, and is not limited to an electromagnetic induction type non-contact power feeding 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 non-contact power feeding 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 and perform non-contact power feeding between the first coil and the second coil. There,
Both the first coil and the second coil are spiral coils,
About the power transmission coil which transmits electric power among the first coil and the second coil, both sides in the vehicle width direction with respect to the power transmission coil so that the entire power transmission coil is hidden in a side view from the vehicle width direction. The flange is erected in
A non-contact power feeding system, wherein a non-conductive magnetic thin film is formed on a surface of the flange on the power transmission coil side.   The non-contact power feeding system according to claim 1, wherein the flange is erected at a position about 75 mm away from the outer periphery of the power transmission coil.   The non-contact power feeding system according to claim 1 or 2, wherein the non-conductive magnetic thin film has a relative permeability of about 50.   The contactless power feeding system according to any one of claims 1 to 3, wherein a protruding height of the flange is equal to a height of a surface of the power transmission coil.   The non-contact electric power feeding system in any one of Claims 1 thru | or 4 whose said flange is a cyclic | annular flange surrounding the outer periphery of the said power transmission coil.   The non-contact electric power feeding system according to any one of claims 1 to 5, wherein the non-conductive magnetic thin film is a coating film formed by applying a magnetic paint.

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