JP5625263B2 - Coil unit, non-contact power transmission device, non-contact power supply system, and electric vehicle - Google Patents

Coil unit, non-contact power transmission device, non-contact power supply system, and electric vehicle Download PDF

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JP5625263B2
JP5625263B2 JP2009120125A JP2009120125A JP5625263B2 JP 5625263 B2 JP5625263 B2 JP 5625263B2 JP 2009120125 A JP2009120125 A JP 2009120125A JP 2009120125 A JP2009120125 A JP 2009120125A JP 5625263 B2 JP5625263 B2 JP 5625263B2
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coil
self
power
resonant
electromagnetic induction
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JP2010267917A (en
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真士 市川
真士 市川
佐々木 将
将 佐々木
達 中村
達 中村
平 菊池
平 菊池
山本 幸宏
幸宏 山本
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トヨタ自動車株式会社
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/60Other road transportation technologies with climate change mitigation effect
    • Y02T10/70Energy storage for electromobility
    • Y02T10/7005Batteries
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/60Other road transportation technologies with climate change mitigation effect
    • Y02T10/70Energy storage for electromobility
    • Y02T10/7022Capacitors, supercapacitors or ultracapacitors
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/10Technologies related to electric vehicle charging
    • Y02T90/12Electric charging stations
    • Y02T90/122Electric charging stations by inductive energy transmission

Description

  The present invention relates to a coil unit, a non-contact power transmission device, a non-contact power feeding system, and an electric vehicle, and more particularly to a shape of a self-resonant coil for improving power transmission efficiency.

  As environmentally friendly vehicles, electric vehicles such as electric vehicles and hybrid vehicles have attracted a great deal of attention. These vehicles are equipped with an electric motor that generates driving force and a rechargeable power storage device that stores electric power supplied to the electric motor. Note that the hybrid vehicle includes a vehicle in which an internal combustion engine is further mounted as a power source together with an electric motor, and a vehicle in which a fuel cell is further mounted together with a power storage device as a DC power source for driving the vehicle.

  As in the case of an electric vehicle, a hybrid vehicle is known that can charge an in-vehicle power storage device from a power source outside the vehicle. For example, a so-called “plug-in hybrid vehicle” that can charge a power storage device from a general household power supply by connecting a power outlet provided in a house and a charging port provided in the vehicle with a charging cable is known. Yes.

  On the other hand, as a power transmission method, wireless power transmission that does not use a power cord or a power transmission cable has recently attracted attention. As this wireless power transmission technology, three technologies known as power transmission using electromagnetic induction, power transmission using electromagnetic waves, and power transmission using a resonance method are known.

  Among them, the resonance method is a non-contact power transmission technique in which a pair of resonators (for example, a pair of self-resonant coils) are resonated in an electromagnetic field (near field) and transmitted through the electromagnetic field. It is also possible to transmit power over a long distance (for example, several meters) (Patent Document 1).

International Publication No. 2007/008646 Pamphlet

  A contactless power transmission device and a power reception device that employ the resonance method include a self-resonant coil that transmits electric power through an electromagnetic field. The self-resonant coil is made by winding a coil material, and the cross-sectional shape of the coil material may be a circular shape. In some cases, the self-resonant coil is manufactured by a member common to the electromagnetic induction coil for inputting or outputting electric power to the self-resonant coil. In this case, the cross-sectional shape of the coil material is the same.

  When power is transmitted by the resonance method, a high-frequency current flows through the self-resonant coil. Here, it is known that when a high-frequency current flows in the coil, the current density is high on the surface of the coil and becomes low as it leaves the surface (so-called skin effect). Therefore, when the current flowing in the coil is high frequency, the substantial electric resistance of the coil is increased as compared with the case of direct current or low frequency.

  In particular, when power is transmitted and received by the resonance method, the power supplied to the self-resonant coil is stored in the inductance and capacitance components of the self-resonant coil and resonates. Therefore, the self-resonant coil is larger than the electromagnetic induction coil. Current flows. Therefore, if the electric resistance of the coil is large, energy loss increases due to heat generated by the resistance, leading to a decrease in transmission efficiency.

  The present invention has been made to solve such a problem, and an object thereof is to improve transmission efficiency in power transmission by the resonance method.

  A coil unit according to the present invention is a coil unit for performing at least one of power transmission and power reception by electromagnetic resonance with a first self-resonant coil arranged opposite to the first self-resonant coil, And an electromagnetic induction coil. The second self-resonant coil performs electromagnetic resonance with the first self-resonant coil. The electromagnetic induction coil is configured to be capable of at least one of power transmission and power reception with the second self-resonant coil by electromagnetic induction. The second self-resonant coil is a coil whose electric resistance per unit length is smaller than that of the electromagnetic induction coil.

  According to this coil unit, since the electrical resistance per unit length is smaller than that of the electromagnetic induction coil, when the member has the same cross-sectional shape as the electromagnetic induction coil (that is, when the electrical resistance per unit length is the same) Compared with, heat generation due to current flowing in the self-resonant coil during resonance can be reduced. As a result, energy loss during power transmission can be reduced, and transmission efficiency can be improved.

  Preferably, the second self-resonant coil and the electromagnetic induction coil have a shape in which a coil material is wound. The second self-resonant coil is a coil in which the length of the coil material surface portion in the cross section of the coil material of the second self-resonant coil is longer than the length of the coil material surface portion in the cross section of the coil material of the electromagnetic induction coil. It is.

  With such a configuration, the surface area of the self-resonant coil can be increased. In the resonance method, the current flowing in the coil becomes a high frequency, so that the current flows only near the coil surface due to the skin effect. Therefore, by increasing the surface area of the coil, a large amount of current can flow (that is, the substantial electrical resistance can be reduced). As a result, energy loss during power transmission can be reduced, and transmission efficiency can be improved.

  Preferably, the second self-resonant coil has a second direction in which the length in the first direction of the cross-sectional shape of the coil material of the second self-resonant coil is perpendicular to the first direction in the cross-sectional shape. It is a coil longer than the length of.

  By setting it as such a structure, the cross-sectional shape of a coil can be flattened. As a result, since the distance from the coil surface to the coil center portion can be shortened, the heat generated in the coil can be easily dissipated, and the cooling performance of the coil can be improved.

  Alternatively, preferably, the coil material of the second self-resonant coil is constituted by a plurality of linear conductors.

  With such a configuration, the surface area of the self-resonant coil can be increased, so that the transmission efficiency during power transmission can be improved.

  A non-contact power transmission device according to the present invention includes the coil unit described above, and performs at least one of power transmission and reception by electromagnetic resonance.

  A non-contact power feeding system according to the present invention includes the above-described non-contact power transmission device in at least one of a power transmission device and a power reception device, and transmits power from a power source to the power reception device by electromagnetic resonance.

  The electric vehicle according to the present invention includes a self-resonant coil, an electromagnetic induction coil, a rectifier, and an electric drive device. The self-resonant coil receives power in a non-contact manner by electromagnetic resonance with a power transmission device provided outside the vehicle. The electromagnetic induction coil is configured such that electric power can be output from the self-resonant coil by electromagnetic induction. The rectifier is configured to receive power from the electromagnetic induction coil and rectify. The electric drive device is configured to receive the electric power rectified by the rectifier and generate a vehicle driving force. The self-resonant coil is a coil whose electric resistance per unit length is smaller than that of the electromagnetic induction coil.

  Preferably, the self-resonant coil and the electromagnetic induction coil have a shape in which a coil material is wound. The self-resonant coil is a coil in which the length of the coil material surface portion in the cross-section of the coil material of the self-resonant coil is longer than the length of the coil material surface portion in the cross-section of the coil material of the electromagnetic induction coil.

  Preferably, the self-resonant coil is a coil in which a length in a first direction of a cross-sectional shape of a coil material of the self-resonant coil is longer than a length in a second direction perpendicular to the first direction in the cross-sectional shape. It is.

  Alternatively, preferably, the coil material of the self-resonant coil is constituted by a plurality of linear conductors.

  According to the present invention, the transmission efficiency can be improved in the transmission of power by the resonance method.

It is a whole lineblock diagram of the non-contact electric supply system according to an embodiment of the invention. It is a figure for demonstrating the principle of the power transmission by the resonance method. It is the figure which showed the relationship between the distance from an electric current source (magnetic current source), and the intensity | strength of an electromagnetic field. It is a figure for demonstrating the skin depth by a skin effect. It is an example of the self-resonant coil shape of the example of examination (when not corresponding to this Embodiment). It is a figure which shows the outline | summary of the coil unit by this Embodiment. It is a figure which shows an example of sectional drawing which shows the cross-sectional shape of the coil material of a self-resonance coil. It is sectional drawing which shows the 1st modification of the cross-sectional shape of the coil material of a self-resonant coil. It is sectional drawing which shows the 2nd modification of the cross-sectional shape of the coil material of a self-resonant coil. It is sectional drawing which shows the 3rd modification of the cross-sectional shape of the coil material of a self-resonant coil. It is sectional drawing which shows the 4th modification of the cross-sectional shape of the coil material of a self-resonant coil. It is sectional drawing which shows the 5th modification of the cross-sectional shape of the coil material of a self-resonant coil. It is sectional drawing which shows the 6th modification of the cross-sectional shape of the coil material of a self-resonance coil.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is an overall configuration diagram of a non-contact power feeding system according to an embodiment of the present invention. Referring to FIG. 1, the non-contact power feeding system includes an electric vehicle 100 and a power feeding device 200. Electric vehicle 100 includes a secondary self-resonant coil 110, a secondary electromagnetic induction coil 120, a rectifier 130, a DC / DC converter 140, and a power storage device 150. Electric vehicle 100 further includes a power control unit (hereinafter also referred to as “PCU (Power Control Unit)”) 160, a motor 170, and a vehicle ECU (Electronic Control Unit) 180.

  The configuration of the electric vehicle 100 is not limited to the configuration shown in FIG. 1 as long as the vehicle is driven by a motor. For example, a hybrid vehicle including a motor and an internal combustion engine, a fuel cell vehicle including a fuel cell, and the like are included.

  Secondary self-resonant coil 110 is disposed, for example, at the bottom of the vehicle body. The secondary self-resonant coil 110 is an LC resonant coil whose both ends are open (not connected), and receives power from the power feeder 200 by resonating with a primary self-resonant coil 240 (described later) of the power feeder 200 via an electromagnetic field. To do. Note that the capacitance component of the secondary self-resonant coil 110 is the stray capacitance of the coil, but a separate capacitor (not shown) may be connected to both ends of the coil in order to obtain a predetermined stray capacitance.

The secondary self-resonant coil 110 and the secondary self-resonant coil 240 are connected to the primary self-resonant coil 240 and the secondary self-resonant coil 240 based on the distance from the primary self-resonant coil 240 and the resonance frequency of the primary self-resonant coil 240 and the secondary self-resonant coil 110. The number of turns is appropriately set so that the Q value (for example, Q> 100) indicating the resonance intensity with the self-resonant coil 110 and κ indicating the degree of coupling increase.

  The secondary electromagnetic induction coil 120 is disposed coaxially with the secondary self-resonant coil 110 and can be magnetically coupled to the secondary self-resonant coil 110 by electromagnetic induction. The secondary electromagnetic induction coil 120 takes out the electric power received by the secondary self-resonant coil 110 by electromagnetic induction and outputs it to the rectifier 130.

  The rectifier 130 rectifies the AC power extracted by the secondary electromagnetic induction coil 120. DC / DC converter 140 converts the power rectified by rectifier 130 into a voltage level of power storage device 150 based on a control signal from vehicle ECU 180 and outputs the voltage to power storage device 150. Note that when receiving power from the power supply apparatus 200 while the vehicle is running, the DC / DC converter 140 may convert the power rectified by the rectifier 130 into a system voltage and directly supply it to the PCU 160. The DC / DC converter 140 is not necessarily required, and the AC power extracted by the secondary electromagnetic induction coil 120 may be directly supplied to the power storage device 150 after being rectified by the rectifier 130.

  The power storage device 150 is a rechargeable DC power source, and is composed of, for example, a secondary battery such as lithium ion or nickel metal hydride. The power storage device 150 stores power supplied from the DC / DC converter 140 and also stores regenerative power generated by the motor 170. Then, power storage device 150 supplies the stored power to PCU 160. Note that a large-capacity capacitor can also be used as the power storage device 150, and is a power buffer that can temporarily store the power supplied from the power supply device 200 and the regenerative power from the motor 170 and supply the stored power to the PCU 160. Anything is acceptable.

  PCU 160 drives motor 170 with power output from power storage device 150 or power directly supplied from DC / DC converter 140. PCU 160 also rectifies the regenerative power generated by motor 170 and outputs the rectified power to power storage device 150 to charge power storage device 150. The motor 170 is driven by the PCU 160 to generate a vehicle driving force and output it to driving wheels. Motor 170 generates power using kinetic energy received from an engine (not shown) in the case of drive wheels or a hybrid vehicle, and outputs the generated regenerative power to PCU 160.

  Vehicle ECU 180 controls DC / DC converter 140 when power is supplied from power supply apparatus 200 to electric vehicle 100. The vehicle ECU 180 controls the voltage between the rectifier 130 and the DC / DC converter 140 to a predetermined target voltage by controlling the DC / DC converter 140, for example. In addition, vehicle ECU 180 controls PCU 160 based on the traveling state of the vehicle and the state of charge of power storage device 150 (also referred to as “SOC (State Of Charge)”) when the vehicle is traveling.

  On the other hand, power supply device 200 includes an AC power supply 210, a high-frequency power driver 220, a primary electromagnetic induction coil 230, and a primary self-resonant coil 240.

  AC power supply 210 is a power supply external to the vehicle, for example, a system power supply. The high frequency power driver 220 converts the power received from the AC power source 210 into high frequency power, and supplies the converted high frequency power to the primary electromagnetic induction coil 230. Note that the frequency of the high-frequency power generated by the high-frequency power driver 220 is, for example, 1 M to several tens of MHz.

  Primary electromagnetic induction coil 230 is arranged coaxially with primary self-resonant coil 240 and can be magnetically coupled to primary self-resonant coil 240 by electromagnetic induction. The primary electromagnetic induction coil 230 supplies the high-frequency power supplied from the high-frequency power driver 220 to the primary self-resonant coil 240 by electromagnetic induction.

  Primary self-resonant coil 240 is disposed near the ground, for example. The primary self-resonant coil 240 is also an LC resonant coil whose both ends are open (not connected), and transmits electric power to the electric vehicle 100 by resonating with the secondary self-resonant coil 110 of the electric vehicle 100 via an electromagnetic field. The capacitance component of the primary self-resonant coil 240 is also a stray capacitance of the coil, but a capacitor (not shown) may be separately connected to both ends of the coil as in the secondary self-resonant coil 110.

  The primary self-resonant coil 240 also has a Q value (for example, Q> based on the distance from the secondary self-resonant coil 110 of the electric vehicle 100, the resonance frequency of the primary self-resonant coil 240 and the secondary self-resonant coil 110, etc. 100), and the number of turns is appropriately set so that the degree of coupling κ and the like are increased.

  FIG. 2 is a diagram for explaining the principle of power transmission by the resonance method. Referring to FIG. 2, in this resonance method, in the same way as two tuning forks resonate, two LC resonance coils having the same natural frequency resonate in an electromagnetic field (near field), and thereby, from one coil. Electric power is transmitted to the other coil via an electromagnetic field.

  Specifically, a primary electromagnetic induction coil 320 is connected to a high frequency power supply 310, and high frequency power of 1 M to several tens of MHz is fed to a primary self-resonant coil 330 that is magnetically coupled to the primary electromagnetic induction coil 320 by electromagnetic induction. To do. The primary self-resonant coil 330 is an LC resonator based on the inductance of the coil itself and stray capacitance (including the capacitance of the capacitor when a capacitor is connected to the coil), and has the same resonance frequency as that of the primary self-resonant coil 330. Resonates with the secondary self-resonant coil 340 having an electromagnetic field (near field). Then, energy (electric power) moves from the primary self-resonant coil 330 to the secondary self-resonant coil 340 via the electromagnetic field. The energy (electric power) moved to the secondary self-resonant coil 340 is taken out by the secondary electromagnetic induction coil 350 that is magnetically coupled to the secondary self-resonant coil 340 by electromagnetic induction and supplied to the load 360. Note that power transmission by the resonance method is realized when the Q value indicating the resonance intensity between the primary self-resonant coil 330 and the secondary self-resonant coil 340 is greater than 100, for example.

  1 will be described. The AC power supply 210 and the high-frequency power driver 220 in FIG. 1 correspond to the high-frequency power supply 310 in FIG. Further, the primary electromagnetic induction coil 230 and the primary self-resonant coil 240 in FIG. 1 correspond to the primary electromagnetic induction coil 320 and the primary self-resonant coil 330 in FIG. 2, respectively, and the secondary self-resonant coil 110 and the secondary electromagnetic in FIG. Induction coil 120 corresponds to secondary self-resonant coil 340 and secondary electromagnetic induction coil 350 in FIG. In addition, the rectifier 130 and the subsequent parts in FIG.

  FIG. 3 is a diagram showing the relationship between the distance from the current source (magnetic current source) and the intensity of the electromagnetic field. Referring to FIG. 3, the electromagnetic field is composed of three components. The curve k1 is a component that is inversely proportional to the distance from the wave source, and is referred to as a “radiated electromagnetic field”. A curve k2 is a component inversely proportional to the square of the distance from the wave source, and is referred to as an “induction electromagnetic field”. The curve k3 is a component inversely proportional to the cube of the distance from the wave source, and is referred to as an “electrostatic magnetic field”.

  The “electrostatic magnetic field” is a region where the intensity of the electromagnetic wave suddenly decreases with the distance from the wave source. In the resonance method, the energy (using the near field (evanescent field) where this “electrostatic magnetic field” is dominant is used. Power) is transmitted. That is, by resonating a pair of resonators having the same natural frequency (for example, a pair of LC resonance coils) in a near field where the “electrostatic magnetic field” is dominant, from one resonator (primary self-resonance coil) Energy (electric power) is transmitted to the other resonator (secondary self-resonant coil). Since this "electrostatic magnetic field" does not propagate energy far away, the resonance method transmits power with less energy loss than electromagnetic waves that transmit energy (electric power) by "radiant electromagnetic field" that propagates energy far away. be able to.

  In power transmission by the resonance method, first, power received from the high-frequency power driver 220 is transmitted from the primary electromagnetic induction coil 230 to the primary self-resonant coil 240 by electromagnetic induction. The primary self-resonant coil 240 stores the transmitted power in the inductance and stray capacitance of the coil itself (including the capacitance of the capacitor when a capacitor is connected to the coil), and performs self-resonance. Generates an electromagnetic field.

  On the other hand, on the power receiving side, the secondary self-resonant coil 110 resonates due to the electromagnetic field generated by the self-resonant of the primary self-resonant coil 240, and the secondary self-resonant coil 110 also self-resonates at the same resonance frequency as the primary self-resonant coil 240. To do. The secondary electromagnetic induction coil 120 takes out the electric power received by the secondary self-resonant coil 110 from the primary self-resonant coil 240 by electromagnetic induction, and transmits the electric power to the load after the rectifier 130. In the secondary electromagnetic induction coil 120, a part of the resonance energy (electric power) of the secondary self-resonant coil 110 is extracted.

  At this time, in the primary self-resonant coil 240 and the secondary self-resonant coil 110 (hereinafter also collectively referred to as “self-resonant coil”), energy (electric power) alternates between inductance and stray capacitance due to self-resonance. When moving to, a current flows through the self-resonant coil. Therefore, energy loss occurs due to heat generated by the electrical resistance of the coil itself.

  Since the primary self-resonant coil 240 stores the power (energy) transmitted from the primary electromagnetic induction coil 230 in the inductance and stray capacitance of the coil itself as described above, the primary self-resonant coil 240 has a power larger than that of the primary electromagnetic induction coil 230. doing. Therefore, for example, if the dimensions and shapes of the primary electromagnetic induction coil 230 and the primary self-resonant coil 240 are the same (the same electrical resistance per unit length), the current flowing in the primary self-resonant coil 240 is the primary electromagnetic The current becomes relatively larger than the current flowing through the induction coil 230, and the energy loss due to heat generation also increases. This also applies to the secondary self-resonant coil 110 and the secondary electromagnetic induction coil 120 on the power receiving side. That is, as described above, in the secondary electromagnetic induction coil 120, only a part of the electric power of the secondary self-resonant coil 110 is taken out. Bigger than.

  Therefore, in order to improve power transmission efficiency in power transmission by the resonance method, it is important to reduce energy loss due to the resistance component of the coil itself when the self-resonant coil resonates.

  Note that the primary electromagnetic induction coil 230 and the secondary electromagnetic induction coil 120 (hereinafter also collectively referred to as “electromagnetic induction coil”) are connected to an external power source on the power supply side, and on the power reception side (vehicle side). Connect to load if present. Therefore, both ends of the electromagnetic induction coil are drawn from a coil case (not shown) that houses the electromagnetic induction coil and the self-resonant coil, and are extended to an external power source or a load. Therefore, since it is necessary to handle both ends of the coil outside the coil case, it is difficult to make the cross-sectional shape of the electromagnetic induction coil complicated. That is, the cross-sectional shape of the electromagnetic induction coil needs to be a relatively simple shape (for example, a circle or a square). By doing in this way, manufacture and handling of a coil material become easy.

  Therefore, in the present embodiment, the electrical resistance per unit length of the primary self-resonant coil 240 and the secondary self-resonant coil 110 that are self-resonant coils is used as the primary electromagnetic induction coil 230 and the secondary electromagnetic induction that are electromagnetic induction coils. By making it smaller than the electrical resistance per unit length of the coil 120, energy loss during power transmission is reduced, and transmission efficiency is improved.

  In general, when a high-frequency current flows through a conductor, it is known that a current flows densely only near the surface of the conductor, and a so-called skin effect occurs in which almost no current flows in the center of the conductor. Yes. This is because when a current is passed through the conductor, a magnetic field is generated in a direction perpendicular to the conductor, but the density of the magnetic field is stronger at the center of the conductor and the current flow is blocked by the counter electromotive force generated by the magnetic field.

  FIG. 4 is a diagram for explaining the skin depth due to the skin effect. The skin depth is a depth at which the current flowing inside the conductor is 1 / e (about 0.37) of the surface current of the conductor, and the skin depth d is generally expressed by the equation (1).

d = (2ρ / ω · μ) 1/2 (1)
ρ: Conductor resistivity ω: Angular frequency of current (= 2π × frequency f)
μ: Magnetic permeability of conductor The horizontal axis of FIG. 4 indicates the frequency f of the current, and the vertical axis indicates the skin depth d. As shown in FIG. 4, the skin depth d decreases exponentially as the frequency f of the current increases. That is, in the high frequency region, it means that the substantial electrical resistance of the conductor increases.

  Therefore, in a self-resonant coil that resonates at a high frequency, in order to reduce the electrical resistance of the coil, simply increase the coil diameter of the coil material and increase the cross-sectional area of the coil material as in the case of direct current or low frequency. It is not always effective to increase the surface area of the coil.

  However, when the surface area of the coil is increased, as shown in FIG. 5, for example, when the coil has a shape having a bellows-like protrusion in the current flow direction (longitudinal direction of the coil material), Although the surface area increases, the distance along the coil surface increases with respect to the direction of current flow. Therefore, in the case of such a shape, there is a possibility that the electrical resistance increases.

  Therefore, in the present embodiment, the length of the coil material surface portion in the cross section of the coil material forming the self-resonant coil is equal to the length of the coil material surface portion in the cross section of the coil material forming the electromagnetic induction coil. The cross-sectional shape is longer than that. By doing so, the surface area of the coil can be increased without increasing the distance in the direction in which the current flows along the coil surface. As a result, when the current is high frequency, the substantial electrical resistance per unit length of the self-resonant coil can be made smaller than the electrical resistance per unit length of the electromagnetic induction coil.

  FIG. 6 shows a schematic diagram of coil unit 400 in the present embodiment. Referring to FIG. 6, coil unit 400 includes an electromagnetic induction coil 410, a self-resonant coil 420, a bobbin 430, and a capacitor 440.

  The electromagnetic induction coil 410 corresponds to the primary electromagnetic induction coil 230 and the secondary electromagnetic induction coil 120 in FIG. The electromagnetic induction coil 410 has a coil material wound around the bobbin 430. Then, it is arranged coaxially with the self-resonant coil 420. Both ends of the electromagnetic induction coil 410 are pulled out of a coil case (not shown) that houses the coil unit 400 and connected to an external power source or a load. The electromagnetic induction coil 410 transmits or receives power with the self-resonant coil 420 by electromagnetic induction.

  In addition, since the electromagnetic induction coil 410 is pulled out of the coil case, the cross section of the coil material is shaped like a solid circle, for example, as described above.

  Self-resonant coil 420 corresponds to primary self-resonant coil 240 and secondary self-resonant coil 110 in FIG. The self-resonant coil 420 is mounted so that a coil material is wound around a cylindrical and insulating bobbin 430. Then, both ends of the self-resonant coil 420 are connected to a capacitor 440 disposed inside the bobbin 430 to constitute an LC resonance circuit. Note that the capacitor 440 is not necessarily required. When a desired capacitance component is realized by the stray capacitance of the self-resonant coil 420, both ends of the self-resonant coil 420 are not connected (open).

  The self-resonant coil 420 performs power transmission or power reception by electromagnetic resonance with another opposing self-resonant coil. In addition, power is received or transmitted by the electromagnetic induction coil 410 and electromagnetic induction.

  The cross-section of the coil material of the self-resonant coil 420 is such that the length of the coil material surface portion in the cross-section of the coil material is larger than that of the electromagnetic induction coil 410. It is made longer than the length of the part.

7 to 13 show examples of the cross-sectional shape of the coil material of the self-resonant coil 420.
FIG. 7 shows an example of the cross-sectional shape of the coil material of the self-resonant coil 420. As shown in FIG. 7, the cross-sectional shape of the coil material of the self-resonant coil 420 is substantially O-shaped, that is, a shape like a pipe with a hollow coil.

  At this time, by making the thickness of the conductor (coil material) sufficiently larger than the skin depth, the surface area of the inner surface portion can be increased compared to a solid conductor having the same outer diameter. Furthermore, since the sectional area of the coil is reduced, the amount of conductor (for example, copper) used can be reduced, so that the cost and weight can be reduced.

  FIG. 8 is a cross-sectional view showing a first modification of the cross-sectional shape of the coil material of the self-resonant coil 420. In the first modification, as shown in FIG. 8, the cross-sectional shape of the coil material is substantially U-shaped. By setting it as such a shape, the surface area of a coil can be increased and the usage-amount of a conductor can be reduced similarly to the case of the cross-sectional shape of FIG. In this case, since the inner surface portion is open, heat generated on the inner surface can be easily radiated as compared with the cross-sectional shape of FIG. 7, and the cooling performance of the coil can be improved.

  FIG. 9 is a cross-sectional view showing a second modification of the cross-sectional shape of the coil material of the self-resonant coil 420. In the second modification, as shown in FIG. 9, the cross-sectional shape of the self-resonant coil 420 is a rectangular flat plate. Further, the rectangular flat plate-shaped cross-sectional member may be bent or curved like a substantially V shape or a substantially M shape.

  FIG. 10 is a sectional view showing a third modification of the sectional shape of the coil material of the self-resonant coil 420. In the third modification, as shown in FIG. 10, the self-resonant coil 420 is composed of a plurality of small-diameter conductors. Thereby, the surface area of a coil can be increased. Furthermore, the stray capacitance can be increased by filling each conductor with a derivative such as silicon resin. In order to obtain a predetermined stray capacitance, it is not necessary to separately arrange a capacitor. Alternatively, even when a separate capacitor is provided, the capacitance of the capacitor can be reduced.

  FIG. 11 is a sectional view showing a fourth modification of the sectional shape of the coil material of the self-resonant coil 420. As shown in FIG. 11, a plurality of concave portions or convex portions may be formed on the outer peripheral surface of the coil.

  FIG. 12 is a cross-sectional view showing a fifth modification of the cross-sectional shape of the coil material of the self-resonant coil 420. In the fifth modification, the length of one direction (for example, B in FIG. 12) having a cross-sectional shape of the coil material is longer than the length in the direction perpendicular to the direction (for example, A in FIG. 12). It has a cross-sectional shape. That is, it has a flat cross-sectional shape such as an ellipse as shown in FIG. By flattening such a cross-sectional shape, the distance from the surface of the coil conductor to the center of the coil conductor is shortened, so that the heat inside the coil conductor is easily radiated and the cooling performance of the coil can be improved. In addition, such a cross-sectional shape is not restricted to an ellipse. Further, the flat cross-sectional shape member may be bent or curved.

  FIG. 13 is a sectional view showing a sixth modification of the sectional shape of the coil material of the self-resonant coil 420. As shown in FIG. 13, the cross-sectional shape of the self-resonant coil 420 may be spiral.

  As described above, in power transmission by the resonance method, the length of the coil material surface portion in the cross section of the coil material forming the self-resonant coils (the primary self-resonant coil 240 and the secondary self-resonant coil 110) is the electromagnetic induction coil. By making the cross-sectional shape longer than the length of the surface portion of the coil material in the cross section of the coil material forming the (primary electromagnetic induction coil 230 and secondary electromagnetic induction coil 120), self-resonance occurs in a region where the current is high frequency. The substantial electrical resistance of the unit length of the coil can be made smaller than the electrical resistance of the unit length of the electromagnetic induction coil. As a result, energy loss in the self-resonant coil can be reduced, so that transmission efficiency during power transmission can be improved.

  The PCU 160 and the motor 170 in the present embodiment are examples of the “electric drive device” in the present invention.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  DESCRIPTION OF SYMBOLS 100 Electric vehicle, 110, 340 Secondary self-resonant coil, 120, 350 Secondary electromagnetic induction coil, 130 Rectifier, 140 DC / DC converter, 150 Power storage device, 160 PCU, 170 Motor, 180 Vehicle ECU, 200 Power feeding device, 210 AC power supply, 220 high frequency power driver, 230, 320 primary electromagnetic induction coil, 240, 330 primary self resonant coil, 310 high frequency power supply, 360 load, 400 coil unit, 410 electromagnetic induction coil, 420 self resonant coil, 430 bobbin, 440 capacitor .

Claims (8)

  1. A coil unit for performing at least one of power transmission and power reception by electromagnetic resonance with a first self-resonant coil disposed oppositely,
    A second self-resonant coil for performing electromagnetic resonance with the first self-resonant coil;
    An electromagnetic induction coil configured to be capable of at least one of power transmission and power reception with the second self-resonant coil by electromagnetic induction,
    The second self-resonant coil and the electromagnetic induction coil have a shape in which a coil material is wound ,
    The second self-resonant coil has a smaller electrical resistance per unit length than the electromagnetic induction coil , and the length of the coil material surface portion in the cross-section of the coil material of the second self-resonant coil is The coil unit is a coil longer than the length of the coil material surface portion in the cross section of the coil material of the electromagnetic induction coil .
  2. The second self-resonant coil has a second direction in which the length in the first direction of the cross-sectional shape of the coil material of the second self-resonant coil is perpendicular to the first direction in the cross-sectional shape. The coil unit according to claim 1 , wherein the coil unit is longer than the coil length.
  3. The coil unit according to claim 1 , wherein the coil material of the second self-resonant coil is configured by a plurality of linear conductors.
  4. It includes coil unit according to any one of claims 1 to 3 carried out at least one of power transmission and power reception by electromagnetic resonance, non-contact power transmission apparatus.
  5. A non-contact power feeding system that transmits power from a power source to a power receiving device by electromagnetic resonance,
    The non-contact electric power feeding system which contains the non-contact electric power transmission apparatus of Claim 4 in at least any one of the said power transmission apparatus and the said power receiving apparatus.
  6. An electric vehicle,
    A self-resonant coil that receives electric power in a non-contact manner by electromagnetic resonance with a power transmission device provided outside the vehicle;
    An electromagnetic induction coil configured to be capable of outputting electric power from the self-resonant coil by electromagnetic induction;
    A rectifier configured to receive and rectify power from the electromagnetic induction coil;
    An electric drive device configured to receive the electric power rectified by the rectifier and generate a vehicle driving force;
    The self-resonant coil and the electromagnetic induction coil have a shape in which a coil material is wound ,
    The self-resonant coil is a coil having an electrical resistance per unit length smaller than that of the electromagnetic induction coil , and the length of the coil material surface portion in the cross-section of the coil material of the self-resonant coil is equal to that of the electromagnetic induction coil. An electric vehicle which is a coil longer than the length of a coil material surface portion in a cross section of the coil material .
  7. The self-resonant coil is a coil in which the length in the first direction of the cross-sectional shape of the coil material of the self-resonant coil is longer than the length in the second direction perpendicular to the first direction in the cross-sectional shape. The electric vehicle according to claim 6 , wherein
  8. The electric vehicle according to claim 6 , wherein the coil material of the self-resonant coil is configured by a plurality of linear conductors.
JP2009120125A 2009-05-18 2009-05-18 Coil unit, non-contact power transmission device, non-contact power supply system, and electric vehicle Active JP5625263B2 (en)

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US8829725B2 (en) 2010-03-19 2014-09-09 Tdk Corporation Wireless power feeder, wireless power receiver, and wireless power transmission system
US8800738B2 (en) 2010-12-28 2014-08-12 Tdk Corporation Wireless power feeder and wireless power receiver
US8742627B2 (en) 2011-03-01 2014-06-03 Tdk Corporation Wireless power feeder
KR20120116802A (en) 2011-04-13 2012-10-23 엘지이노텍 주식회사 A wireless power transmission system and a wireless power receiver using a relay device
CN103534771A (en) 2011-05-19 2014-01-22 丰田自动车株式会社 Power-reception device, power-transmission device, and power-transfer system
JP2013012637A (en) * 2011-06-30 2013-01-17 Yazaki Corp Power supply system
CN103843084A (en) * 2011-10-04 2014-06-04 丰田自动车株式会社 Power reception device, power transmission device, and power transmission system
JP5885239B2 (en) 2011-10-20 2016-03-15 トヨタ自動車株式会社 Power receiving device, power transmitting device, and power transmission system
JP6302365B2 (en) * 2014-06-20 2018-03-28 矢崎総業株式会社 Coil device for non-contact power supply
KR101701045B1 (en) 2015-06-09 2017-01-31 삼성전기주식회사 Coil structure for wireless power transfer and wireless power transmitter comprising thereof

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EP1010229A4 (en) * 1997-05-06 2001-02-14 Auckland Uniservices Ltd Inductive power transfer across an extended gap
JPH11186086A (en) * 1997-12-17 1999-07-09 Tokin Corp Manufacture of spiral coil for noncontact power transmitter
CN102361358B (en) * 2007-03-27 2015-07-29 麻省理工学院 Wireless energy transfer
WO2009023155A2 (en) * 2007-08-09 2009-02-19 Nigelpower, Llc Increasing the q factor of a resonator
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WO2009037821A1 (en) * 2007-09-17 2009-03-26 Hideo Kikuchi Induced power transmission circuit
JP5160858B2 (en) * 2007-10-25 2013-03-13 メレアグロス株式会社 A coil of a power transmission device, a power transmission device, a power transmission device of the power transmission device, and a power reception device of the power transmission device.
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