JP2017034029A - Resonator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of suppressing reduction of power transmission efficiency due to Joule heat in a resonator.SOLUTION: A resonator 30 is used as a transmission side resonator 21 and a reception side resonator 25, in a noncontact power supply system 10 for use in wireless power supply. The resonator 30 includes a coil 33 for use in resonance of magnetic field, a reflector 34, i.e., a metal plate placed at a position where the magnetic flux generated in the coil 33 passes, and suppressing leakage of the magnetic flux, an insulation member 35, i.e., a ceramic member placed between the coil 33 and the reflector 34 in contact with at least the coil 33, and a resin housing 36 housing the coil 33, the reflector 34 and the insulation member 35.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resonator.

  In the non-contact power supply system, wireless power supply is performed by using magnetic field resonance in a resonator (for example, Patent Documents 1-3 below). Some resonators include a metallic reflector for suppressing leakage of magnetic flux generated in a coil.

JP 2013-55229 A JP 2014-146664 A JP 2014-43115 A

  In the resonator, Joule heat is generated in the coil itself. Further, an eddy current may be generated in the reflecting plate due to the magnetic flux passing through the reflecting plate, and Joule heat may be generated in the reflecting plate due to the eddy current. Joule heat generated in the resonator causes a reduction in power transmission efficiency. Therefore, in the resonator, it is desirable that generation of Joule heat is suppressed. It is also desirable that Joule heat be radiated efficiently.

  SUMMARY An advantage of some aspects of the invention is to solve at least the problems described above, and the invention can be implemented as the following forms.

[1] According to an aspect of the present invention, a resonator is provided. This resonator may be used for wireless power feeding. The resonator may include a coil, a metal plate, and a ceramic member. The coil may be used for magnetic field resonance. The metal plate may be disposed at a position where magnetic flux generated in the coil passes. The ceramic member may be disposed between the coil and the metal plate at least in contact with the coil. According to the resonator of this form, the heat dissipation of the coil is enhanced by heat conduction through the ceramic member. Further, since the distance between the metal plate and the coil is ensured at least by the thickness of the ceramic member, the generation of Joule heat due to the eddy current generated in the metal plate is suppressed. Therefore, energy loss caused by Joule heat generated in the resonator is suppressed, and a decrease in power transmission efficiency is suppressed.

[2] In the resonator of the above aspect, the ceramic member may be disposed in contact with both the coil and the metal plate. According to the resonator of this form, the heat dissipation of the coil is further improved. In addition, the resonator can be reduced in size.

[3] In the resonator according to the above aspect, the metal plate may have a heat radiation fin on a surface opposite to a surface facing the coil. According to the resonator of this form, the heat dissipation from the metal plate is further enhanced.

[4] In the resonator according to the above aspect, the ceramic member may have a thermal conductivity of 33 W / mK or more and 200 W / mK or less. According to the resonator of this form, the heat dissipation of the coil by the ceramic member is further enhanced.

[5] In the resonator according to the above aspect, a distance between the coil and the metal plate may be 10 mm or more and 20 mm or less. According to the resonator of this form, Joule loss due to eddy current generated in the metal plate is reduced.

[6] The resonator according to the above aspect further includes a resin casing that accommodates at least the coil, the ceramic member, and the metal plate, and the surface of the metal plate is It may be exposed to the outside from the part. According to the resonator of this form, the configuration can be made compact.

  A plurality of constituent elements of each aspect of the present invention described above are not indispensable, and some or all of the effects described in the present specification are to be solved to solve part or all of the above-described problems. In order to achieve the above, it is possible to appropriately change, delete, replace with another new component, and partially delete the limited contents of some of the plurality of components. In order to solve part or all of the above-described problems or to achieve part or all of the effects described in this specification, technical features included in one embodiment of the present invention described above. A part or all of the technical features included in the other aspects of the present invention described above may be combined to form an independent form of the present invention.

  The present invention can be realized in various forms other than the resonator. For example, it can be realized in the form of a power transmission device or power reception device including a resonator, a non-contact power supply device, a wireless power supply system, or an electronic device or a moving body including at least a power transmission device or a power reception device.

Schematic which shows the structure of a non-contact electric power feeding system. The schematic perspective view which shows the external appearance of a resonator. The schematic perspective view which shows the internal structure of a resonator. The schematic perspective view which shows the internal structure of a resonator.

A. Embodiment:
FIG. 1 is a schematic diagram showing a configuration of a non-contact power feeding system 10 including resonators 21 and 25 as an embodiment of the present invention. The non-contact power supply system 10 includes a power transmission device 11 and a power reception device 12, and transmits electric power from the power transmission device 11 to the power reception device 12 in a non-contact state by a magnetic resonance method (magnetic resonance coupling method). In the present embodiment, the non-contact power supply system 10 is applied to a power supply facility that performs wireless power supply to an electric vehicle. The power transmission device 11 of the non-contact power supply system 10 is installed on the floor surface of a garage, and the power reception device 12 is mounted on the lower part of the electric vehicle.

  The power transmission device 11 includes a power transmission side resonator 21, a high frequency power source 22, and a matching circuit 23. The power transmission-side resonator 21 resonates at a predetermined frequency to generate electromagnetic energy by receiving supply of high-frequency power. Details of the configuration of the power transmission side resonator 21 will be described later. The high frequency power supply 22 converts power supplied from a commercial power supply or the like into high frequency power having a predetermined frequency, and supplies the high frequency power to the power transmission resonator 21 via the matching circuit 23. The matching circuit 23 performs impedance matching that matches the impedance of the high-frequency power source 22 with the impedance of the power transmission resonator 21.

  The power receiving device 12 includes a power receiving side resonator 25, a matching circuit 26, a rectifier 27, and a battery 28. The power receiving side resonator 25 generates high frequency power by resonating at a predetermined frequency of the electromagnetic field energy generated by the power transmitting side resonator 21. The power reception side resonator 25 has substantially the same configuration as the power transmission side resonator 21. Details of the configuration of the power receiving resonator 25 will be described later.

  The matching circuit 26 supplies the rectifier 27 with the high frequency power generated in the power receiving side resonator 25 while performing impedance matching that matches the impedance of the power receiving side resonator 25 and the impedance of the rectifier 27. The rectifier 27 rectifies the high-frequency power, converts it to DC power, and supplies it to the battery 28. The battery 28 stores the DC power supplied from the rectifier 27. The electric vehicle uses the electric power stored in the battery 28 as a driving force.

  In the non-contact power feeding system 10, when the power transmission side resonator 21 and the power reception side resonator 25 are arranged so as to face each other with a predetermined distance, the two resonators 21 and 25 are magnetically resonance coupled. As a result, power is transmitted from the power transmission device 11 to the power reception device 12. The transmission of power between the power transmission device 11 and the power reception device 12 is controlled by the control units (not shown) included in the power transmission device 11 and the power reception device 12 cooperating with each other via wireless communication. The

  With reference to FIGS. 2-4, the structure of the power transmission side resonator 21 and the power receiving side resonator 25 in this embodiment is demonstrated. As described above, since the power transmission side resonator 21 and the power reception side resonator 25 have substantially the same configuration, the power transmission side resonator 21 and the power reception side resonator 25 are hereinafter referred to unless otherwise specified. Without distinction, they are collectively referred to as “resonator 30”. FIG. 2 is a schematic perspective view showing the appearance of the resonator 30. 3 and 4 are schematic perspective views showing the internal structure of the resonator 30. FIG. FIG. 3 shows a state in which a part of the resonator 30 is removed and a part of the internal coil 33 is exposed. 4, the exposed part of the internal structure of the resonator 30 in FIG. 3 is shown enlarged.

  The resonator 30 has a flat, substantially rectangular parallelepiped shape, and includes a first surface 31 and a second surface 32 on the opposite side (FIG. 2). When power is transmitted between the power transmission device 11 and the power reception device 12, the two resonators 30 are arranged to face each other so that the first surfaces 31 face each other. The second surface 32 of the power transmission side resonator 21 is in contact with the ground or outside air, and the second surface 32 of the power reception side resonator 25 is in contact with the body of the electric vehicle or outside air.

  The resonator 30 includes a coil 33, a reflecting plate 34, an insulating member 35, and a casing 36 (FIGS. 3 and 4). In the resonator 30, the coil 33, the reflection plate 34, and the insulating member 35 are housed in a compact manner in the internal space of the housing portion 36. In the present embodiment, the casing 36 is made of an insulating resin, and is formed by injection molding so as to cover the outer peripheral end of the resonator 30 and the entire first surface 31 side. (FIG. 2). In the central region on the second surface 32 side of the housing portion 36, a window portion 36w for exposing the central portion 34c of the reflecting plate 34 is formed as a substantially rectangular opening.

  In the present embodiment, the coil 33 has a configuration in which a conductive wire whose outer surface is covered with an insulator is wound in an approximately annular shape many times (FIGS. 3 and 4). The thickness of the coil 33 in the direction along the central axis is about 3 to 5 mm. The coil 33 has a main body part 33b in which a conducting wire is wound in an annular shape, and a terminal part 33t extending in the radial direction from the outer peripheral end of the main body part 33b. The main body portion 33b is disposed in a substantially central region of the first surface 31 when the resonator 30 is viewed along its thickness direction. Further, the main body portion 33 b is disposed at a substantially central position in the thickness direction of the resonator 30.

  The terminal portion 33t extends from the outer peripheral end of the main body portion 33b and protrudes to the outside at the side surface portion of the housing portion 36 (FIG. 2). The terminal portion 33t mediates electrical connection between the two ends of the conductive wire constituting the main body portion 33b of the coil 33 and the connection terminal of the matching circuit 23 (FIG. 1).

  The reflection plate 34 is a metal plate disposed at a position where the magnetic flux generated in the coil 33 passes in the thickness direction. The reflection plate 34 adjusts the direction of the magnetic flux generated in the coil 33 and improves the directivity of the magnetic flux. Control leaks. The reflecting plate 34 is preferably made of a nonmagnetic material. Moreover, it is desirable to be comprised with the metal with high heat conductivity. In the present embodiment, the reflection plate 34 is made of aluminum. The reflection plate 34 is disposed at a position on the second surface 32 side with respect to the coil 33 and at a position separated from the coil 33.

  As described above, the central portion 34c on the second surface 32 side of the reflecting plate 34 is exposed to the outside through the window portion 36w provided in the housing portion 36 (FIG. 2). When the resonator 30 is viewed along its thickness direction, the entire body 33b of the coil 33 is accommodated in the region of the central portion 34c of the reflector 34. On the surface of the central portion 34c of the reflecting plate 34, heat radiating fins 34f are provided over the entire surface. In the present embodiment, the heat radiating fins 34f are formed as a plurality of parallel linear protrusions (ribs).

  The insulating member 35 is made of, for example, a ceramic member whose main component is alumina. The insulating member 35 is formed in a plate shape. One surface of the insulating member 35 is configured to be flat. On the other surface of the insulating member 35, a concave portion 35c is formed in the shape of the main body portion 33b and the terminal portion 33t of the coil 33. In the resonator 30, the insulating member 35 is arranged such that the flat surface side is the second surface 32 side and the surface side having the recess 35 c is the first surface 31 side. The flat surface of the insulating member 35 is in surface contact with the reflecting plate 34. The coil 33 is fitted and held in the concave portion 35 c of the insulating member 35, and the region outside the concave portion 35 c is in contact with the housing portion 36. The insulating member 35 is sandwiched between the coil 33 and the reflecting plate 34 in the formation region of the recess 35c, and is sandwiched between the reflecting plate 34 and the wall portion on the first surface 31 side of the housing portion 36 in the outer region. .

  As described above, the resonator 30 of the present embodiment has a configuration in which the insulating member 35 is disposed between the coil 33 and the reflecting plate 34 so as to contact both the coil 33 and the reflecting plate 34. doing. According to the resonator 30 of the present embodiment, since the reflection plate 34 is provided, leakage of magnetic flux at the time of power transmission is suppressed, so that reduction in power transmission efficiency due to leakage of magnetic flux is suppressed. Further, a separation distance L between the coil 33 and the reflecting plate 34 is ensured by the amount of the insulating member 35 interposed between the coil 33 and the reflecting plate 34 (FIG. 4). By ensuring the separation distance L, the eddy current generated in the reflecting plate 34 when the magnetic flux generated in the coil 33 passes through the reflecting plate 34 is suppressed from being excessively increased. Heat generation is suppressed. Therefore, energy loss due to generation of Joule heat in the reflector 34 is reduced, and a reduction in power transmission efficiency is suppressed.

  Here, the separation distance L between the coil 33 and the reflecting plate 34 is preferably 10 mm or more. This is because, if the separation distance L is smaller than 10 mm, for example, when a current of several kW or more flows through the coil 33, the eddy current generated in the reflection plate 34 may become too large. The separation distance L is desirably 20 mm or less. This is because when the separation distance L is greater than 20 mm, for example, when a current of several kW or more flows through the coil 33, the leakage of magnetic flux by the reflecting plate 34 may not be sufficiently suppressed. Therefore, the separation distance L between the coil 33 and the reflecting plate 34 is more preferably 10 mm or more and 20 mm or less.

  In the resonator 30 of the present embodiment, the insulating member 35 is in direct contact with the coil 33 and the reflecting plate 34. Thereby, the Joule heat generated in the coil 33 can be efficiently transmitted to the reflecting plate 34 via the insulating member 35 made of a ceramic member having high thermal conductivity. Therefore, the heat dissipation of the coil 33 is enhanced, and the generation of energy loss due to Joule heat generated in the coil 33 during power transmission is suppressed. In addition, thermal deterioration of the coil 33 and the casing 36 is suppressed. In addition, the insulation between the coil 33 and the reflecting plate 34 is enhanced by the insulating member 35.

  Here, the insulating member 35 is preferably made of a ceramic member having a thermal conductivity of 33 W / mK or more. If it is this ceramic member, the heat dissipation of the coil 33 is ensured. The insulating member 35 is preferably composed of a ceramic member having a thermal conductivity of 200 W / mK or less. In general, ceramic members with high thermal conductivity tend to have low electrical resistance. A ceramic member having a thermal conductivity of 200 W / mK or less can ensure high insulation between the coil 33 and the reflecting plate 34 while improving the heat dissipation of the coil 33. Therefore, it is more desirable that the insulating member 35 is composed of a ceramic member having a thermal conductivity of 33 W / mK or more and 200 W / mK or less. Note that a thermal conductivity of 33 W / mK or more and 200 W / mK or less can be obtained by using a ceramic member mainly composed of alumina or a ceramic member mainly composed of aluminum nitride. A ceramic member mainly composed of alumina is relatively inexpensive and has excellent cost. A ceramic member mainly composed of aluminum nitride can ensure a higher thermal conductivity than a ceramic member mainly composed of alumina.

  Furthermore, in the resonator 30 according to the present embodiment, since the heat radiating fins 34f are provided on the reflection plate 34, the heat dissipation by the reflection plate 34 is enhanced. Moreover, the heat dissipation by the reflecting plate 34 is also improved by the reflecting plate 34 being made of aluminum having high thermal conductivity. In addition, in the resonator 30 of this embodiment, as described above, the coil 33 and the reflecting plate 34 are in direct contact with the insulating member 35, and the coil 33, the reflecting plate 34, and the insulating member 35 are in contact with each other. There is no useless space between them, and the resonator 30 is thinned. Further, since the coil 33 is held in the concave portion 35 c of the insulating member 35, the fixing property and the protection property of the coil 33 are enhanced. In the resonator 30 of this embodiment, the coil 33, the reflection plate 34, and the insulating member 35 are integrated in a compact manner by the housing unit 36, and the size is reduced.

  As described above, with the resonator 30 (the power transmission side resonator 21 and the power reception side resonator 25) of the present embodiment, energy loss due to Joule heat generated in the coil 33 and the reflection plate 34 is reduced, and contactlessness is achieved. A decrease in power transmission efficiency in the power feeding system 10 is suppressed. In addition, the various functions and effects described above can be achieved.

B. Variations:
B1. Modification 1:
In the above embodiment, the insulating member 35 is in direct contact with both the coil 33 and the reflecting plate 34. On the other hand, the insulating member 35 may not be in contact with the reflection plate 34, and may be disposed between the coil 33 and the reflection plate 34 at least in contact with the coil 33. For example, a member having high thermal conductivity such as silicon may be interposed between the insulating member 35 and the reflecting plate 34. In the said embodiment, the insulating member 35 has the recessed part 35c for arrange | positioning the coil 33 fittingly. On the other hand, the recess 35c may be omitted.

B2. Modification 2:
In the above embodiment, the reflecting plate 34 has the rib-shaped heat radiation fins 34f. On the other hand, the reflecting plate 34 may not have the heat radiating fins 34f. Further, instead of the rib-shaped heat radiation fins 34f, heat radiation fins having other shapes may be provided. The radiation fins only need to have a shape protruding in the thickness direction of the reflector so that the surface area of the reflector 34 increases. In the above embodiment, the reflecting plate 34 is made of aluminum. On the other hand, the reflecting plate 34 may be made of a metal other than aluminum. The reflecting plate 34 may be made of, for example, stainless steel or copper. In the above embodiment, the central portion 34 c of the reflecting plate 34 is exposed to the outside through the window portion 36 w of the housing portion 36. On the other hand, the central portion 34c of the reflecting plate 34 may not be exposed to the outside, and may be covered by the wall portion of the housing portion 36, for example.

B3. Modification 3:
In the said embodiment, the coil 33 has the structure by which the conductor was wound by multiple rings in the annular | circular shape. On the other hand, the coil 33 may have other configurations, for example, a solenoid coil.

B4. Modification 4:
The resonator 30 of the above embodiment is applied to the non-contact power feeding system 10 used in the power feeding facility of the electric vehicle. On the other hand, the resonator 30 may be applied to a power feeding system for a mobile body other than an electric vehicle, or a portable device such as a notebook computer or a mobile phone.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above-described effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Non-contact electric power feeding system 11 ... Power transmission apparatus 12 ... Power receiving apparatus 21 ... Power receiving side resonator 22 ... High frequency power supply 23 ... Matching circuit 25 ... Power transmission side resonator 26 ... Matching circuit 27 ... Rectifier 28 ... Battery 30 ... Resonator 31 ... 1st surface 32 ... 2nd surface 33 ... Coil 33b ... Body part 33t ... Terminal part 34 ... Reflector 34c ... Central part 34f ... Radiation fin 35 ... Insulating member 35c ... Recess 36 ... Housing part 36w ... Window part

Claims (6)

A resonator used for wireless power feeding,
A coil used for magnetic field resonance;
A metal plate disposed at a position where magnetic flux generated in the coil passes;
At least a ceramic member disposed between the coil and the metal plate in contact with the coil;
A resonator comprising: The resonator according to claim 1,
The ceramic member is a resonator arranged in contact with both the coil and the metal plate. The resonator according to claim 1 or 2, wherein
The said metal plate is a resonator which has a radiation fin in the surface on the opposite side to the surface facing the said coil. The resonator according to any one of claims 1 to 3,
The ceramic member has a thermal conductivity of 33 W / mK or more and 200 W / mK or less. The resonator according to any one of claims 1 to 4, wherein:
The resonator between the coil and the metal plate is 10 mm or more and 20 mm or less. The resonator according to any one of claims 1 to 5, further comprising:
At least, comprising a resin casing that accommodates the coil, the ceramic member, and the metal plate,
The surface of the said metal plate is a resonator exposed outside from the said housing | casing part.

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