JP2017099186A - Power receiving device and power transmission system - Google Patents

Abstract

PURPOSE: To provide a power receiving device and a power transmission system, capable of suppressing an influence of a magnetic field on the inside or the periphery of the device while suppressing an increase in weight and an increase in cost.CONSTITUTION: The power receiving device includes: a power receiving coil disposed opposite a power transmission coil and receiving electric power transmitted from the power transmission coil in a noncontact manner; and an annular conductor having an annular shape surrounding a central axis of the power reception coil and an annular conductor disposed in a plane in a direction opposing the power transmission coil from the coil surface of the power reception coil.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a power receiving device that receives power in a contactless manner and a power transmission system that transmits power in a contactless manner.

  2. Description of the Related Art In recent years, power transmission systems that transmit power in a contactless manner when power is supplied to wearable devices such as watches and electric vehicles have been used. In such a power transmission system, a coil on the power transmission device side (power transmission coil) and a coil on the power reception device side (power reception coil) are arranged so as to face each other to transmit power. As a power transmission method, an electromagnetic induction method using electromagnetic induction and a magnetic field resonance method using magnetic field resonance are known. In the electromagnetic induction method, a magnetic field is generated by causing a current to flow through a power transmission coil, and a current is generated in the power receiving coil using an induced magnetic flux. In the magnetic field resonance method, a capacitor is connected to the power transmission coil and the power reception coil to form a resonance circuit, and the power transmission coil and the power reception coil resonate at the same frequency, thereby generating a current in the power reception coil.

  In such a power transmission system, a strong magnetic field is generated in order to transmit power. Therefore, in order to reduce the influence of the generated magnetic field on the surroundings of the power transmitting device and the power receiving device, a metal or magnetic material is placed on the surface of the case of the power transmitting device storing the power transmitting coil or the case of the power receiving device storing the power receiving coil. It has been considered to shield the magnetic field by providing a shielding shield made of (for example, Patent Document 1).

Japanese Patent No. 5759761

  The shielding shield as described above is provided so as to close the openings of the power transmission coil and the power reception coil. Therefore, for example, when an electronic device such as a watch or a wearable terminal is a power receiving device, if the power receiving coil is disposed around the display unit, the display unit is blocked by the shielding shield, and the display unit cannot be visually recognized. For this reason, a display part cannot be provided around the opening part of a receiving coil, and there existed a problem that the design of an electronic device will be restrict | limited.

  Further, since the shielding shield is provided so as to close the opening of the power receiving coil, the amount of material used is large. For this reason, there existed a problem that the weight of a power receiving apparatus increased and cost increased.

  In order to solve the above problems, an object of the present invention is to provide a power receiving device capable of suppressing the influence of a magnetic field on the inside and the surroundings of the device while suppressing an increase in weight and an increase in cost.

  A power receiving device according to the present invention is disposed opposite to a power transmitting coil, has a power receiving coil that receives power transmitted from the power transmitting coil in a contactless manner, and an annular shape surrounding a central axis of the power receiving coil, And an annular conductor disposed in a plane in a direction facing the power transmission coil from the coil surface of the power reception coil.

  In addition, a power transmission system according to the present invention includes a power transmission coil that transmits power, a power reception coil that is disposed to face the power transmission coil, and that receives power transmitted from the power transmission coil in a contactless manner, and the power reception coil And an annular conductor disposed so as to be located between a plane including the coil surface of the power receiving coil and a plane including the coil surface of the power transmission coil. And

  According to the present invention, it is possible to suppress the influence of a magnetic field on the inside and the surroundings of the apparatus while suppressing an increase in weight and an increase in cost.

It is the figure (FIG. 1 (a)) and top view (FIG.1 (b)) which show typically the structure of the power receiving apparatus of this invention. It is a figure (Drawing 2 (a)) and a top view (Drawing 2 (b)) showing typically composition of a power transmission device of the present invention. It is a circuit diagram which shows the structure of a power transmission circuit (FIG.3 (a)) and a power receiving circuit (FIG.3 (b)). They are a perspective view (Drawing 4 (a)), a top view (Drawing 4 (b)), and a sectional view (Drawing 4 (c)) showing typically a positional relation of a receiving coil, an annular conductor, and a transmitting coil. It is a figure which compares and compares the magnetic force line of the magnetic field produced in the electric power transmission system of Example 1 with the magnetic force line of a magnetic field when an annular conductor does not exist. FIG. 6 is a diagram (FIG. 6A) and a plan view (FIG. 6B) schematically illustrating a configuration of a power receiving device according to a second embodiment. It is the upper side figure (Drawing 7 (a)) and sectional view (Drawing 7 (b)) which show typically the positional relationship of the receiving coil of Example 2, a ring conductor, and a power transmission coil. It is a figure which compares the magnetic force line of the magnetic field produced in the electric power transmission system of Example 2 with the magnetic force line of a magnetic field when an annular conductor does not exist. It is a figure which shows typically the structure of a power receiving apparatus in case an annular conductor is formed in the same plane as a power receiving apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1A is a diagram schematically showing the configuration of the power receiving device 10, and FIG. 1B is a horizontal sectional view (plan view) taken along line 1a-1b in FIG. 1A. is there. The power receiving device 10 is a device such as a watch, for example, and includes a main body 11, a power receiving coil 12, and an annular conductor 13. In addition, illustration of the main-body part 11 is abbreviate | omitted in FIG.1 (b).

  The main body 11 includes electronic circuits such as a power receiving circuit, a liquid crystal display (LCD), and a circuit board. The main body 11 is disposed at a position facing the annular conductor 13 with the power receiving coil 12 interposed therebetween. When the vicinity of the arrangement region of the main body 11 in the power receiving device 10 is the front side and the vicinity of the arrangement region of the annular conductor 13 is the back side, the liquid crystal display unit is opposite to the front side surface portion (the surface opposite to the power receiving coil 12 of the main body 11). Side surface portion). Moreover, you may have a magnetic shield etc. in the position by the side of the receiving coil 12. FIG.

  The power receiving coil 12 is, for example, a circular coil having an annular coil surface (opening). The power receiving coil 12 is disposed so as to face a power transmitting coil 21 described later at the time of power reception, and receives the power transmitted from the direction A shown in FIG. As will be described later, the power receiving coil 12 is connected to a rectifier circuit, a load, and the like to form a power receiving circuit.

  The annular conductor 13 has an annular shape surrounding the central axis of the power receiving coil 12 and is made of a conductive material such as copper or stainless steel. The diameter of the annular conductor 13 is larger than the diameter of the power receiving coil 12. The annular conductor 13 is provided at a position facing the main body 11 via the power receiving coil 12. When viewed from the A direction, the annular conductor 13 is arranged at a position closer to the power transmission side than the power receiving coil 12 during power transmission.

  2A is a diagram schematically illustrating the structure of the power transmission device 20, and FIG. 2B is a horizontal sectional view (plan view) taken along line 2a-2b in FIG. 2A. is there.

  The power transmission coil 21 is a circular coil having a circular coil surface (opening). The power transmission coil 21 transmits power in the B direction shown in FIG. An AC current source, a power amplifier, and a resonant capacitor are connected to the power transmission coil 21 to constitute a power transmission circuit.

  FIG. 3A is a circuit diagram showing the configuration of the power transmission circuit 23. The power transmission circuit 23 includes an alternating current source AC, a power amplifier PA, and a power transmission side resonance circuit 22. The power transmission side resonance circuit 22 includes a power transmission coil 21 and a resonance capacitor C1 connected in series.

  The AC current source AC generates an AC current (AC signal) having a frequency of 13.56 MHz, which is used as a frequency band of, for example, an ISM (Industry Science Medical) band. The power amplifier PA amplifies the generated alternating current and supplies it to the power transmission side resonance circuit 22. The power transmission side resonance circuit 22 resonates at a resonance frequency of 13.56 MHz and generates an AC magnetic field.

  FIG. 3B is a circuit diagram illustrating a configuration of the power receiving circuit 14 including the power receiving coil 12. The power receiving circuit 14 includes a power receiving side resonance circuit 15, a rectifier circuit 16, and a load RX. The power reception side resonance circuit 15 includes a power reception coil 12 and a resonance capacitor C2 connected in parallel. The rectifier circuit 16 includes rectifier diodes D1 to D4.

  The power reception side resonance circuit 15 resonates at the same resonance frequency as that of the power transmission side resonance circuit 22, that is, a resonance frequency of 13.56 MHz due to the fluctuation of the magnetic field generated by the resonance of the power transmission side resonance circuit 22. Thereby, an alternating current having a frequency of 13.56 MHz is generated in the power receiving side resonance circuit 15.

  The power reception side resonance circuit 15 supplies the generated alternating current to the rectification circuit 16. The rectifier circuit 16 converts alternating current into direct current and supplies it to the load RX.

  The load RX is, for example, a battery provided in the power receiving device 10. That is, power is transmitted from the power transmission circuit 23 to the power reception circuit 14 by the operation of each of the above parts, and the battery of the power reception device 10 is charged.

  Referring again to FIGS. 1A and 1B, the annular conductor 13 is formed of a closed annular conductor line, and no capacitor is connected. Therefore, although the annular conductor 13 has a certain stray capacitance, the resonance frequency thereof is greatly different from the resonance frequency 13.56 MHz of the power transmission side resonance circuit 22 and the power reception side resonance circuit 15.

  FIG. 4A is a perspective view schematically showing a positional relationship among the power receiving coil 12, the annular conductor 13, and the power transmitting coil 21 (hereinafter collectively referred to as a power transmission system) during power transmission. FIG. 4B is a top view of such a power transmission system, and FIG. 4C is a cross-sectional view taken along line VV of the top view including the central axis Ax of the power receiving coil 12.

  The annular conductor 13 is disposed in a plane in a direction facing the power transmission coil 21 from the coil surface of the power reception coil 12. That is, the annular conductor 13 is disposed between the plane including the coil surface of the power transmission coil 21 and the plane including the coil surface of the power reception coil 12 so as to surround the central axis of the power reception coil 12. The diameter of the annular conductor 13 is larger than the diameter of each of the power receiving coil 12 and the power transmitting coil 21.

  5A and 5B are a cross-sectional view (FIG. 5B) of magnetic field lines of a magnetic field generated around the power transmission coil 21, the power reception coil 12, and the annular conductor 13 in this embodiment, and a provisional annular conductor. FIG. 6 is a diagram schematically showing a cross-sectional view (FIG. 5A) of magnetic field lines of a magnetic field generated around the power transmission coil 21 and the power reception coil 12 when 13 is not present.

  When the annular conductor 13 is not present, an AC magnetic field is widely generated around the power transmission coil 21 and the power reception coil 12 as indicated by a broken line in FIG. In the present invention, the power transmission side resonance circuit 22 and the power reception side resonance circuit 15 are resonated at the same frequency (13.56 MHz) as described above, and power is transmitted using a so-called magnetic field resonance method. Occur. Therefore, the spread of the magnetic field formed around the power transmission coil 21 and the power receiving coil 12 is large, and the influence of the magnetic field on the peripheral region of each coil, such as the inside or the outside of the power receiving device 10, is large.

  On the other hand, when the annular conductor 13 exists between the plane including the coil surface of the power transmission coil 21 and the plane including the coil surface of the power receiving coil 12, the induction is induced in the annular conductor 13 by the magnetic field generated by the power transmission coil 21. A current flows, and a magnetic field is generated around the annular conductor 13 in a direction that cancels the magnetic field generated by the power transmission coil 21. Therefore, the spread of the magnetic field formed around the power transmission coil 21 and the power receiving coil 12 is reduced, and the influence of the magnetic field on the peripheral region of each coil, such as the inside or the outside of the power receiving device 10, is reduced.

  The magnetic field generated around the annular conductor 13 has a function of canceling the spread of the magnetic field generated around the power transmission coil 21 and the power receiving coil 12, but has an effect on the amount of power transmitted from the power transmission circuit 23 to the power reception circuit 14. Does not reach.

  In the above description, the diameter of the annular conductor 13 is larger than the diameter of the power receiving coil 12. However, in this embodiment, the annular conductor 13 has a shape and size including the power receiving coil 12. good. That is, it is only necessary that the annular conductor 13 has a shape including the power receiving coil 12 when the power receiving coil 12 and the conductor surface of the annular conductor 13 are placed in the same plane.

  As described above, according to the power receiving device 10 of the present embodiment, the influence of the magnetic field generated during power transmission between the power transmission coil 21 and the power receiving coil 12 on the peripheral region of the power receiving device 10 can be reduced.

  Further, since the annular conductor 13 is disposed at a position facing the main body 11 with the power receiving coil 12 interposed therebetween, the front surface portion of the power receiving device 10 (opposite to the surface facing the power receiving coil 12 of the main body 11). This does not hinder the visual recognition of the liquid crystal display portion and the like formed on the side surface portion. Further, since the annular conductor 13 has an annular shape and uses a small amount of material, an increase in the weight and cost of the power receiving device can be suppressed as compared with the case where a plate-shaped shielding shield is provided.

  A power receiving apparatus and a power transmission system according to the present embodiment will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected about the structure similar to Example 1, and description is abbreviate | omitted.

  FIG. 6A is a diagram schematically showing the configuration of the power receiving device 30 of the present embodiment, and FIG. 6B is a horizontal sectional view taken along line WW in FIG. 6A. Is a plan view). The power receiving device 30 is an electronic device such as a watch, for example, and includes a main body 11, a power receiving coil 32, and an annular conductor 33. In addition, illustration of the main-body part 11 is abbreviate | omitted in FIG.6 (b).

  In the power receiving device 30 of the present embodiment, the diameter of the annular conductor 33 is different from the diameter of the annular conductor 13 of the power receiving device 10 of the first embodiment. That is, unlike the first embodiment, the diameter of the annular conductor 33 is smaller than the diameter of the power receiving coil 32.

  Fig.7 (a) is a top view which shows typically the positional relationship of the receiving coil 32, the annular conductor 33, and the power transmission coil 21 (electric power transmission system) at the time of electric power transmission. FIG. 7B is a cross-sectional view taken along line XX in FIG. 7A and includes the central axis Ax of the power receiving coil 32.

  An annular conductor 33 is disposed between a plane including the coil surface of the power transmission coil 21 and a plane including the coil surface of the power reception coil 32 so as to surround the central axis of the power reception coil 32. Further, the diameter of the annular conductor 33 is smaller than the diameter of each of the power receiving coil 32 and the power transmitting coil 21.

  FIGS. 8A and 8B are a cross-sectional view (FIG. 8B) of magnetic field lines of a magnetic field generated around the power transmission coil 21, the power reception coil 32, and the annular conductor 33 in this embodiment, and a provisional annular conductor. FIG. 9 is a diagram schematically showing a cross-sectional view (FIG. 8A) of magnetic field lines of a magnetic field generated around the power transmission coil 21 and the power reception coil 32 when 33 is not present.

  When the annular conductor 33 is not present, an alternating magnetic field is widely generated around the power transmission coil 21 and the power reception coil 32 as indicated by a broken line shown in FIG. Therefore, the spread of the magnetic field formed around the power transmission coil 21 and the power reception coil 32 is large, and the influence of the magnetic field on the peripheral region of each coil, such as inside or outside the power reception device 30, is large.

  On the other hand, when the annular conductor 33 exists between the plane including the coil surface of the power transmission coil 21 and the plane including the coil surface of the power receiving coil 32, the annular conductor 33 is guided by the magnetic field generated by the power transmission coil 21. A current flows, and a magnetic field is generated around the annular conductor 33 in a direction to cancel the magnetic field generated by the power transmission coil 21.

  In this embodiment, since the diameter of the ring of the annular conductor 33 is smaller than the diameter of each of the power reception coil 32 and the power transmission coil 21, the power reception coil in the inner region (region close to the central axis) of the power reception coil 32 and the power transmission coil 21. 32 and the spread of the magnetic field generated around the power transmission coil 21 are suppressed. Accordingly, the influence of the magnetic field on the periphery of the power transmission coil 21 and the power reception coil 12, particularly on the inner region of the coil is reduced.

  In the above description, it is assumed that the diameter of the annular conductor 33 is smaller than the diameter of the power receiving coil 32. However, in this embodiment, the annular conductor 33 may have the shape and size included in the power receiving coil 32. It ’s fine. That is, it is only necessary that the annular conductor 33 has a shape included in the power receiving coil 32 when the conductor surfaces of the power receiving coil 32 and the annular conductor 33 are placed in the same plane.

  As described above, according to the power receiving device 30 of the present embodiment, the magnetic field generated during power transmission between the power transmission coil 21 and the power receiving coil 32 affects the peripheral region of the power receiving device 30, particularly the inside of the power receiving device 30. Can be reduced. Thus, for example, when the power receiving device 30 is a precision device such as a watch or a portable terminal, it is possible to greatly reduce the influence of the magnetic field on the precision components inside the device.

  In addition, this invention is not limited to the said embodiment. For example, in Example 1 and Example 2 described above, the example in which the annular conductor 13 (33) is disposed at a position closer to the power transmission side than the coil surface of the power receiving coil 12 (32) has been described. However, for example, as shown in FIG. 9, the annular conductor 13 (33) may be formed in the same plane (for example, the same layer) as the power receiving coil 12 (32).

  Further, in the above-described embodiment, the example using the magnetic field resonance method in which the power transmission coil and the power reception coil transmit power by resonating at a common resonance frequency has been described. However, electric power may be transmitted by an electromagnetic induction method in which power is transmitted from the power transmission coil to the power reception coil by electromagnetic induction.

  Moreover, although the said Example demonstrated the example in which a power transmission coil and a receiving coil resonate at the resonance frequency of 13.56 MHz, a frequency band is not restricted to this. For example, a short wave frequency band such as 6.78 MHz or a long wave frequency band of about 100 kHz may be used. In short, it is sufficient if the power transmission coil and the power reception coil are configured to resonate at the same resonance frequency.

  The annular conductor 13 may be in an electrically floating state, may be grounded, or may be connected to some circuit.

  Moreover, in the said Example, the receiving coil 12 (32), the power transmission coil 21, and the cyclic | annular conductor 13 (33) demonstrated as an example the case where it had an annular | circular shape. However, it may have an elliptical shape, a rectangular shape such as a rectangle, or a ring shape such as a polygonal ring.

  The power receiving coil 12 (32) and the power transmitting coil 21 may be a plurality of coils wound in a cylindrical shape. Further, the annular conductor 13 (33) may be formed in a plurality of coil shapes or spring shapes. The annular conductor 13 (33) may be arranged in a plane in a direction facing the power transmission coil 21 from the coil surface of the power reception coil 12 (32). For example, the power reception coil 12 (32) has n turns (n: Any one of the first to nth coil surfaces can be used as the coil surface of the power receiving coil 12 (32).

  Further, in the above-described embodiment, an example in which the load RX that receives the supplied power is the battery of the power receiving device 10 and charging is performed based on the transmitted power has been described. However, the purpose of power transmission is not limited to charging. For example, bi-directional or unidirectional communication may be performed using the transmitted power by modulating an AC signal (AC current).

  Moreover, the said Example demonstrated the example in which an annular conductor is formed in a power receiving apparatus. However, the annular conductor may be formed in the power transmission device. In short, the annular conductor may be disposed between a plane including the coil surface of the power receiving coil and a plane including the coil surface of the power transmission coil.

  Moreover, the role of a receiving coil and a power transmission coil may be reversed by switch switching etc., and you may be comprised so that the electric power transmission of a reverse direction is possible.

  In order to further suppress the influence of the magnetic field on the periphery, a conventionally used magnetic sheet or conductor plate may be used in combination with the annular conductor of the present invention.

DESCRIPTION OF SYMBOLS 10,30 Power receiving apparatus 11 Main-body part 12, 32 Power receiving coil 13, 33 Annular conductor 14 Power receiving circuit 15 Power receiving side resonance circuit 16 Rectifier circuit 20 Power transmission apparatus 21 Power transmission coil 22 Power transmission side resonance circuit 23 Power transmission circuit

Claims (14)

A power receiving coil that is arranged to face the power transmitting coil and receives the power transmitted from the power transmitting coil in a contactless manner;
An annular conductor having a ring shape surrounding a central axis of the power receiving coil, and an annular conductor disposed in a plane facing the power transmission coil from a coil surface of the power receiving coil;
A power receiving device comprising: A capacitor connected to the power receiving coil;
The power reception device according to claim 1, wherein the power reception coil and the capacitor constitute a resonance circuit that resonates at a predetermined resonance frequency.   The power receiving device according to claim 1, wherein the annular conductor has a size and a shape including the power receiving coil.   The power receiving device according to claim 1, wherein the annular conductor has a size and a shape included in the power receiving coil.   The power receiving device according to claim 1, wherein the annular conductor has an annular shape and is larger than a diameter of the power receiving coil.   The power receiving device according to claim 1, wherein the annular conductor has an annular shape and is smaller than a diameter of the power receiving coil.   The power receiving device according to any one of claims 1 to 6, wherein the annular conductor is formed in the same plane as the power receiving coil. A power transmission coil for transmitting power;
A power receiving coil that is disposed to face the power transmitting coil and that receives power transmitted from the power transmitting coil in a contactless manner;
An annular conductor having an annular shape surrounding the central axis of the power receiving coil, and being disposed so as to be located between a plane including the coil surface of the power receiving coil and a plane including the coil surface of the power transmitting coil;
A power transmission system comprising: A power transmission side capacitor connected to the power transmission coil, and a power reception side capacitor connected to the power reception coil,
The power transmission coil and the power transmission side capacitor constitute a power transmission side resonance circuit that resonates at a predetermined resonance frequency,
The power transmission system according to claim 8, wherein the power receiving coil and the power receiving side capacitor constitute a power receiving side resonance circuit that resonates at the predetermined resonance frequency.   The power transmission system according to claim 8 or 9, wherein the annular conductor has a size and a shape including the power receiving coil.   The power transmission system according to claim 8 or 9, wherein the annular conductor has a size and a shape included in the power receiving coil.   The power transmission system according to claim 8 or 9, wherein the annular conductor has an annular shape and is larger than a diameter of the power transmission coil and a diameter of the power reception coil.   The power transmission system according to claim 8 or 9, wherein the annular conductor has an annular shape and is smaller than a diameter of the power transmission coil and a diameter of the power reception coil.   14. The power transmission system according to claim 8, wherein the annular conductor is formed in the same plane as the power receiving coil.

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