JP6916917B2 - Contactless power supply system - Google Patents

Description

The present invention relates to a non-contact power supply system, and more particularly, a non-contact power supply system for a plug-in hybrid vehicle or an electric vehicle that performs non-contact power supply between a power transmission coil installed on the ground and a power reception coil installed on the lower surface of a vehicle body. With respect to suitable techniques.

For plug-in hybrid vehicles (PHEV) and electric vehicles (EV) that are battery-charged with external power, wireless power supply (non-contact power supply) due to the hassle of connecting the charging cable, dirt on clothes, and anxiety in rainy weather. ) Needs are increasing.

The non-contact power supply includes an electromagnetic induction type that uses electromagnetic induction between the primary coil on the ground side and the secondary coil on the vehicle side, and a magnetic field resonance type that uses magnetic field resonance. Of these, the electromagnetic induction type has a very high power transmission efficiency, but is characterized in that the primary coil and the secondary coil must be sufficiently close to each other. On the other hand, the magnetic field resonance type may have a certain distance between the primary coil and the secondary coil, but is characterized in that the power transmission efficiency is lower than that of the electromagnetic induction type. Conventionally, an electromagnetic induction type non-contact power feeding device that suppresses the influence of leakage flux outside the vehicle body even if there is a misalignment between the power feeding unit (primary coil) and the power receiving unit (secondary coil) has been proposed (for example). , Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-49230

There are helical coil and spiral coil as coil types used in non-contact power feeding system, but it was decided to adopt spiral coil as primary coil and secondary coil in the international standardization of non-contact power feeding system for automobiles. .. Spiral coils are more susceptible to the metal on the back of the coil than helical coils. For example, if there is a metal member in the vicinity of the secondary coil, there is a problem that an eddy current is generated in the metal member due to the magnetic flux generated in the primary coil, and the power transmission efficiency is lowered. In order to solve this problem, for example, it is conceivable to spread the core and the magnetic material sheet in a wide range on the vehicle body side, but since the lower surface of the vehicle body has a complicated shape, the processing of the core and the magnetic material sheet is costly. There is a problem that it is difficult to attach it to the lower surface of the vehicle body. In addition, there is a concern that the weight of the vehicle body will increase, and that the core and the magnetic sheet are fragile and easily damaged.

In view of the above problems, it is an object of the present invention to suppress the eddy current in the metal member on the vehicle body side by a simple method in the non-contact power feeding system for automobiles.

In the non-contact power feeding system according to one aspect of the present invention, the power transmitting coil installed on the ground and the power receiving coil installed on the lower surface of the vehicle body face each other to perform non-contact power feeding between the power transmitting coil and the power receiving coil. In a contact power supply system, both the power transmitting coil and the power receiving coil are spiral coils, and the power receiving coil is attached to a metal member directly or indirectly via a coil core to receive power on the surface of the metal member. The non-conductive magnetic thin film is formed in a certain range centered on the mounting position of the coil, and the non-magnetic conductor does not intervene between the power receiving coil and the non-conductive magnetic thin film.

According to this, it is possible to suppress the eddy current in the metal member on the vehicle body side and improve the power transmission efficiency by a simple method such as forming a non-conductive magnetic thin film in a certain range of the mounting position of the power receiving coil.

Preferably, the diameter of the non-conductive magnetic thin film is made larger by about 150 mm to 350 mm than the diameter of the power receiving coil.

According to this, the area for forming the non-conductive magnetic thin film can be made smaller to improve the power transmission efficiency.

More preferably, the diameter of the non-conductive magnetic thin film is made larger than the diameter of the power receiving coil by about 250 mm.

According to this, the area for forming the non-conductive magnetic thin film can be made as small as possible to ensure good power transmission efficiency.

Preferably, the shape of the non-conductive magnetic thin film is made such that the shape of the power transmission coil is stretched in the vehicle width direction.

According to this, it is possible to cope with the misalignment between the power transmitting coil and the power receiving coil, particularly the misalignment in the vehicle width direction.

Since the power transmission efficiency does not change much even if the relative magnetic permeability of the non-conductive magnetic thin film is increased too much, the relative magnetic permeability of the non-conductive magnetic thin film is appropriately about 50.

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

According to this, it is possible to suppress the eddy current in the metal member on the vehicle body side and improve the power transmission efficiency by a simple method such as applying a magnetic paint to a certain range of the mounting position of the power receiving coil.

According to the present invention, an eddy current in a metal member on the vehicle body side is formed by a simple method such as forming a non-conductive magnetic thin film in a certain range of the mounting position of the power receiving coil without laying a core or a magnetic material sheet on the lower surface of the vehicle body. It is possible to improve the power transmission efficiency by suppressing the above.

Schematic of a non-contact power supply system according to an embodiment of the present invention Plan view and cross-sectional view of a power transmission coil according to an example Plan view and cross-sectional view of the power receiving coil according to an example Bottom view of the vehicle body where the power receiving coil is installed The figure explaining the magnetic flux between a power transmission coil and a power reception coil The figure explaining the magnetic flux between a power transmission coil and a power reception coil (without a core). A graph showing the relationship between the diameter of the magnetic coating film and the power transmission efficiency when the power receiving coil is large. A graph showing the relationship between the diameter of the magnetic coating film and the power transmission efficiency when the power receiving coil is small. Graph showing the relationship between the relative permeability of magnetic paint and power transmission 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 explanations of already well-known matters and duplicate explanations for substantially the same configuration may be omitted. This is to avoid unnecessary redundancy of the following description and to facilitate the understanding of those skilled in the art.

It should be noted that the inventors (or others) intend to limit the subject matter described in the claims by those skilled in the art by providing the accompanying drawings and the following description in order to fully understand the present invention. It is not something to do. In addition, the dimensions, thickness, detailed shape of details, etc. of each member drawn in the drawing may differ from the 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 supply system according to the present embodiment is a magnetic field resonance type non-contact power supply system that wirelessly charges the battery 30 of an automobile 100 such as a plug-in hybrid vehicle or an electric vehicle.

In the non-contact power supply 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 terrestrial device 200 can communicate with each other by wireless 300. The automobile 100 determines the charge amount of the battery 30, and requests the ground device 200 to appropriately start / stop the power supply through the wireless 300. The ground device 200 controls the supply / stop of electric energy to the automobile 100 according to the request from the automobile 100.

When supplying electrical 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 energized to the power transmission unit 60 through the cable 201. A power transmission coil (primary coil) (not shown) is housed in the power transmission unit 60, and a strong magnetic field is generated in the power transmission unit 60 by energizing the power transmission coil with a high-frequency current.

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 vertically opposed to the power transmission unit 60. The gap between the power receiving unit 10 and the power transmission unit 60 is 100 to 160 mm.

The power receiving unit 10 includes a resonance circuit composed of a power receiving coil (secondary coil) and a capacitor (not shown), and the resonance circuit resonates when the power receiving 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 in the battery 30. As described above, in the system according to the present embodiment, electric energy is wirelessly supplied from the ground device 200 to the automobile 100 by magnetic field resonance.

An inverter 40 is connected to the battery 30. When the automobile 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 which is the power source of the automobile 100.

FIG. 2 is a plan view and a cross-sectional view of the 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 in which an insulated coated electric wire 62 having a diameter of 5.4 mm is wound in a circular spiral shape in two stages eight times, 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.

FIG. 3 is a plan view and a cross-sectional view of the power receiving coil according to an example. The power receiving coil 11 is housed in the power receiving unit 10. The power receiving coil 11 is a spiral coil in which an insulating coated electric wire 12 having a diameter of 5.4 mm is wound in a circular spiral shape in one stage eight times, 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 formed of a magnetic material such as ferrite. The diameter of the coil core 13 is 400 mm.

The shape of the power receiving coil 11 does not have to be the same as the shape of the power transmission coil 61. For example, the outer diameter and inner diameter of the power receiving coil 11 may be smaller than the above by 100 mm (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 attaching the power receiving unit 10 becomes easy.

Further, both the power transmitting coil 61 and the power receiving coil 11 do not have to be circular. For example, the power transmission coil 61 and / or the power reception coil 11 may be oval or elliptical long in the vehicle width direction.

FIG. 4 is a bottom view of the vehicle body on which the power receiving coil is installed. The power receiving unit 10 is installed, for example, between the left and right rear wheels at the rear of the vehicle. The lower surface of the automobile 100 is covered with an undercover 101 made of iron, aluminum, or the like, and the power receiving coil 11 housed in the power receiving unit 10 is attached to such an undercover 101. More specifically, the coil core 13 to which the power receiving coil 11 is attached is attached to the undercover 101.

Further, a circular magnetic coating film 14 is formed on the surface of the undercover 101 so as to surround the power receiving coil 11. The magnetic coating film 14 can be formed by applying a coating material (magnetic coating material) containing magnetic powder particles obtained by pulverizing a magnetic material such as ferrite to a median diameter of about 20 μm to a thickness of several mm. The magnetic coating film 14 has the characteristics of high magnetic permeability and high electrical resistance, can concentrate magnetic flux, and can suppress loss due to eddy current.

Since the magnetic coating film 14 is exposed to the external environment, it is desirable to apply a rust preventive treatment to the magnetic paint, or to apply a rust preventive treatment to the surface of the magnetic coating film 14 after applying the magnetic paint.

The magnetic coating film 14 is an example of the "non-conductive magnetic thin film" described in the claims. Instead of applying the magnetic paint, a magnetic film or the like may be attached to the surface of the undercover 101 in a circular shape. Alternatively, a circular magnetic thin film may be formed on the surface of the undercover 101 by a method such as plating or vapor deposition. Hereinafter, for convenience of explanation, a magnetic coating film formed by applying a magnetic paint will be described as an example.

FIG. 5 is a diagram for explaining the magnetic flux between the power transmission coil and the power reception coil. The figure is a side view of the power transmission coil 61 and the power reception coil 11. For convenience, the power receiving coil 11 is drawn smaller than the power transmission coil 61.

When a high-frequency current is applied to the power transmission coil 61, a magnetic field as shown by the magnetic flux 70 is generated in the power transmission coil 61. When the magnetic flux 70 generated by the power transmission coil 61 is transmitted to the power reception coil 11, a high frequency current is generated in the power reception coil 11 due to magnetic field resonance. Further, when the magnetic flux 70 generated by the power transmission coil 61 penetrates the metal undercover 101, an eddy current is generated in the undercover 101 and the power transmission efficiency is lowered. However, in the present embodiment, since the magnetic coating film 14 is formed on the surface of the undercover 101, the magnetic flux 70 penetrating the undercover 101 is very small. As a result, the eddy current of the undercover 101, which causes a transmission loss of electric energy, is reduced, and the power transmission efficiency can be kept good.

The shape of the magnetic coating film 14 may be a shape obtained by extending the shape of the power transmission coil 61 in the vehicle width direction. When the automobile 100 is parked in a predetermined position for charging the battery, the position in the vehicle length direction can be regulated by the vehicle stop, whereas there is no such thing in the vehicle width direction and the position in the vehicle width direction cannot be regulated. It is considered that the position shift of the power receiving unit 10 in the vehicle width direction with respect to the power transmission unit 60 is likely to occur. Therefore, the shape of the magnetic coating film 14 is preliminarily made into a shape obtained by extending the shape of the transmission coil 61 in the vehicle width direction. For example, the shape of the magnetic coating film 14 is longer in the vehicle width direction with respect to the circular power transmission coil 61. By making the shape oval or elliptical, the magnetic shielding effect of the magnetic coating film 14 can be obtained even if the power transmitting coil and the power receiving coil are slightly misaligned.

Further, the coil core 13 can be omitted. FIG. 6 is a diagram illustrating a magnetic flux between a power transmitting coil and a power receiving coil (without a core). By appropriately adjusting the thickness of the magnetic coating film 14 in this way, the magnetic coating film 14 can be used not only for suppressing the eddy current in the undercover 101 but also as the core of the power receiving coil 11.

Next, the demonstration result of the power transmission efficiency in the non-contact power supply system according to the present embodiment is shown. Table 1 shows the conditions under each condition when the power transmission coil 61 shown in FIG. 2 and the power receiving coil 11 shown in FIG. 3 are opposed to each other at a distance of 150 mm and a high frequency current of 3 kW in the 85 kHz band is applied to the power transmission coil 61. Shows power transmission efficiency. "Power receiving coil: large" represents a power receiving coil 11 having the same size as the power transmission coil 61 (outer diameter 350 mm, inner diameter 260 mm), and "power receiving coil: small" means a power receiving coil 11 (outer diameter) smaller than the power transmission coil 61. 250 mm, inner diameter 160 mm). "With metal plate" means that the power receiving coil 11 (more specifically, coil core 13) is attached to an iron plate having a thickness of 2 mm, a length of 600 mm, and a width of 500 mm assuming an undercover 101. There is no such iron plate. “With magnetic coating film” means that a magnetic coating film 14 having a relative magnetic permeability of 100 is formed on the entire surface of the iron plate with a thickness of 1 mm.

As can be seen from Table 1, the presence of the magnetic coating film 14 improves efficiency as compared with the case without the magnetic coating film 14, regardless of the size of the power receiving coil 11. In particular, when the power receiving coil 11 becomes small, it tends to be strongly influenced by the metal plate, but by forming the magnetic coating film 14, the efficiency can be improved more than when there is no metal plate.

As described above, the power transmission efficiency can be improved by forming the magnetic coating film 14 on the surface of the undercover 101, but applying the magnetic paint to the entire surface of the undercover 101 is costly. Therefore, in consideration of cost, it is preferable to apply the magnetic paint to the minimum necessary area to form the magnetic coating film 14.

FIG. 7 is a graph showing the relationship between the diameter of the magnetic coating film 14 and the power transmission efficiency when the power receiving coil is large (the outer diameter of the power receiving coil 11 is 350 mm, the inner diameter is 260 mm, and the diameter of the coil core 13 is 400 mm). In the range where the diameter of the magnetic coating film 14 is smaller than or slightly larger than the diameter of the power receiving coil 11 (the diameter of the magnetic coating film 14 is around 0 to 400 mm), the efficiency does not change much, but the diameter of the magnetic coating film 14 is large. Efficiency is significantly improved from around 50 mm larger than the diameter of the power receiving coil 11 (around 400 mm in diameter of the magnetic coating film 14), and when the diameter of the magnetic coating film 14 is 250 mm or more larger than the diameter of the power receiving coil 11 (magnetism). (Diameter 600 mm or more of the coating film 14) The improvement of efficiency becomes slow.

FIG. 8 is a graph showing the relationship between the diameter of the magnetic coating film 14 and the power transmission efficiency when the power receiving coil is small (the outer diameter of the power receiving coil 11 is 250 mm, the inner diameter is 160 mm, and the diameter of the coil core 13 is 300 mm). Even when the power receiving coil 11 is small, the efficiency does not change much in the range where the diameter of the magnetic coating film 14 is smaller than or slightly larger than the diameter of the power receiving coil 11 (the diameter of the magnetic coating film 14 is around 0 to 300 mm). However, the efficiency is remarkably improved from the point where the diameter of the magnetic coating film 14 is about 50 mm larger than the diameter of the power receiving coil 11 (around 300 mm in diameter of the magnetic coating film 14), and the diameter of the magnetic coating film 14 is the diameter of the power receiving coil 11. If it is 250 mm or more larger than the diameter (the diameter of the magnetic coating film 14 is 500 mm or more), the improvement of efficiency becomes slow.

From the above, it can be said that the diameter of the magnetic coating film 14 may be made larger by about 150 mm to 350 mm than the diameter of the power receiving coil 11 regardless of the size of the power receiving coil 11. Further, in order to satisfy the contradictory requirements such as improving the power transmission efficiency while reducing the area of the magnetic coating film 14, the diameter of the magnetic coating film 14 may be increased by about 250 mm from the diameter of the power receiving coil 11.

On the other hand, it is expected that the power transmission efficiency is improved when the relative magnetic permeability of the magnetic paint is higher than when it is low, but in consideration of cost, it is preferable to minimize the relative magnetic permeability of the magnetic paint.

FIG. 9 is a graph showing the relationship between the relative magnetic permeability of the magnetic paint and the power transmission efficiency. The outer diameter of the power transmitting coil 61 and the power receiving coil 11 is 350 mm and the inner diameter is 260 mm, the diameters of the coil cores 63 and 13 are 400 mm, and the thickness of the magnetic coating film 14 is 1 mm and the diameter is 500 mm. The efficiency is improved when the relative magnetic permeability of the magnetic paint is in the range of 0 to 50, but the improvement of efficiency is slowed down when the relative magnetic permeability exceeds 50. Therefore, it can be said that the relative magnetic permeability of the magnetic paint may be about 50. Since magnetic saturation limits efficiency improvement, it is preferable to set the saturation magnetic flux density to 30 mT or more in order to avoid magnetic saturation.

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

Therefore, among the components described in the attached 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, the fact that those non-essential components are described in the accompanying drawings and detailed description should not immediately determine that those non-essential components are essential.

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

In the above, for convenience, the technique in the present invention has been described by taking a magnetic field resonance type non-contact power feeding system as an example, but the present invention is not limited to the magnetic field resonance type non-contact power feeding system, and the present invention is not limited to the magnetic field resonance type non-contact power feeding system. It can also be applied to power supply systems.

Further, in the above, it is assumed that the magnetic coating film 14 is formed on the power receiving coil 11 side, but the magnetic coating film may be formed on the power transmission coil 61 side. For example, when the power transmission unit 60 is installed in a multi-storey car park or the like, the power transmission coil 61 may have to be directly attached to a metal member such as a steel frame due to space restrictions. In such a case, by applying a magnetic paint to the surface of a metal member such as a steel frame to form a magnetic coating film, the magnetic flux penetrating the metal member is reduced and an eddy current is generated in the metal member. Can be reduced to maintain good power transmission efficiency.

11 Power receiving coil 13 Coil core 14 Magnetic coating film (non-conductive magnetic thin film)
61 Power transmission coil 101 Undercover (metal member)

Claims (7)

A non-contact power supply system in which a power transmission coil installed on the ground and a power reception coil installed on the lower surface of a vehicle body face each other to perform non-contact power supply between the power transmission coil and the power reception coil.
Both the power transmission coil and the power reception coil are spiral coils, and the power transmission coil and the power reception coil are spiral coils.
It has been indirectly attached to the metal member through the power receiving coil child Irukoa,
A non-conductive magnetic thin film is formed on the surface of the metal member so as to surround the power receiving coil in a certain range centered on the mounting position of the power receiving coil.
A non-contact power feeding system characterized in that a non-magnetic conductor does not intervene between the power receiving coil and the non-conductive magnetic thin film. The non-contact power feeding system according to claim 1, wherein the diameter of the non-conductive magnetic thin film is 150 mm to 350 mm larger than the diameter of the power receiving coil. The non-contact power feeding system according to claim 2, wherein the diameter of the non-conductive magnetic thin film is 250 mm larger than the diameter of the power receiving coil. The non-contact power feeding system according to any one of claims 1 to 3, wherein the shape of the non-conductive magnetic thin film is a shape obtained by extending the shape of the power transmission coil in the vehicle width direction. The non-contact power feeding system according to any one of claims 1 to 4, wherein the non-conductive magnetic thin film has a relative magnetic permeability of about 50. The non-contact 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. The non-contact power feeding system according to any one of claims 1 to 6, wherein the metal member is iron.

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