JP2010073885A - Resonance coil and non-contact feeding system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent spark discharge from occurring in a resonance coil used for a non-contact feeding system using a resonance technique. <P>SOLUTION: Each of a secondary self-resonant coil 110 and a primary self-resonant coil 240 includes a coil wire 410 constituting a coil and an insulating resin 420. The coil wire 410 electrically resonates at a predetermined resonance frequency. The resin 420 is coated to the coil wire 410 in a shape of taper so that its thickness increases as the location approaches to the end of the coil wire 410 according to the electric field distribution of the coil wire 410. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resonance coil and a contactless power supply system, and more particularly to a resonance coil used when power is transmitted / received using a resonance method and a contactless power supply system using the resonance coil.

  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. The hybrid vehicle is a vehicle in which an internal combustion engine is further mounted as a power source together with an electric motor, or 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 these, the resonance method is a non-contact power transmission technique in which a pair of resonators (for example, a pair of resonance 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) (see Non-Patent Document 1).
International Publication No. 2007/008646 Pamphlet Andre Kurs, 5 others, “Wireless Power Transfer via Strongly Coupled Magnetic Resonances”, [online], July 6, 2007, SCIENCE 317, p. 83-86, [Search September 12, 2007], Internet <URL: http://www.sciencemag.org/cgi/reprint/317/5834/83.pdf>

  In the configuration disclosed in the above document, the resonance coil is composed of an LC resonance coil whose both ends are open (not connected). Here, the electric field distribution of the coil conductor constituting the resonance coil becomes higher as it is closer to the end of the coil conductor. When the configuration disclosed in the above document is applied to a power supply system for an electric vehicle that can receive a large power of several kW to several tens of kW, the electric field is broken down at the end of the coil conductor or near the end. Exceeding the limit, spark discharge can occur.

  Therefore, an object of the present invention is to prevent the occurrence of spark discharge in a resonance coil used in a non-contact power feeding system using a resonance method.

  According to the present invention, the resonance coil is a resonance coil that transmits power to or receives power from the other coil by resonating with another coil via an electromagnetic field, and the coil is insulated from the coil conductor. Resin. The coil conductor is electrically resonated at a predetermined resonance frequency. The resin is coated on the coil conductor so that the thickness increases as the end of the coil conductor is closer.

Preferably, the thickness of the resin is determined according to the electric field distribution of the coil conductor.
Preferably, the resin is coated in a taper shape from the non-central portion to the end portion of the coil conductor.

  Moreover, according to this invention, a non-contact electric power feeding system is provided with a primary coil, a primary self-resonance coil, a secondary self-resonance coil, a secondary coil, and a rectifier. The primary coil receives power from the power source. The primary self-resonant coil is fed by electromagnetic induction from the primary coil and generates an electromagnetic field. The secondary self-resonant coil receives power from the primary self-resonant coil by resonating with the primary self-resonant coil via the electromagnetic field. The secondary coil takes out the electric power received by the secondary self-resonant coil by electromagnetic induction. The rectifier rectifies the electric power extracted by the secondary coil and supplies it to the load. Each of the primary self-resonant coil and the secondary self-resonant coil includes a coil conductor and an insulating resin. The coil conductor is electrically resonated at a predetermined resonance frequency. The resin is coated on the coil conductor so that the thickness increases as the end of the coil conductor is closer.

Preferably, the thickness of the resin is determined according to the electric field distribution of the coil conductor.
Preferably, the resin is coated in a taper shape from the non-central portion to the end portion of the coil conductor.

  In this invention, since the insulating resin is coated on the coil conductor so that the thickness increases as the end of the coil conductor is closer, the limit value of dielectric breakdown is higher as the end of the coil conductor is closer. Therefore, according to the present invention, it is possible to prevent the occurrence of spark discharge in the resonance coil used in the non-contact power feeding system using the resonance method.

  According to the present invention, the thickness of the resin is not made uniform over the entire length of the coil lead wire, but the thickness is increased as it is closer to the end portion, so that the amount of resin can be reduced and the weight of the coil can be reduced. it can. Moreover, the heat dissipation of a coil can also be ensured.

  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 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.

  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.

  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 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.

  In the secondary self-resonant coil 110, the end portion of the coil conductor and the vicinity thereof have a high electric field. In order to prevent a spark discharge into the air in the high electric field portion, the coil conductor is made of an insulating resin. The end portion and the vicinity thereof are coated. The configuration of secondary self-resonant coil 110 will be described in detail later.

  The secondary 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 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 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. DC / DC converter 140 is not necessarily required, and the AC power extracted by secondary coil 120 may be directly rectified by rectifier 130 and then directly supplied to power storage device 150.

  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 electricity using kinetic energy received from driving wheels or an engine (not shown), 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 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 power received from the AC power source 210 into high frequency power, and supplies the converted high frequency power to the primary coil 230. Note that the frequency of the high-frequency power generated by the high-frequency power driver 220 is, for example, 1M to 10 and several MHz.

  Primary 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 coil 230 feeds 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. Note that the capacitance component of the primary self-resonant coil 240 is also a stray capacitance of the coil.

  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.

  In the primary self-resonant coil 240 also, the end portion of the coil conductor and the vicinity thereof have a high electric field, and the end portion of the coil conductor and the vicinity thereof are coated with an insulating resin. The configuration of the primary self-resonant coil 240 will also be described in detail later.

  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, the primary coil 320 is connected to the high frequency power supply 310, and 1 M to 10 and several MHz high frequency power is supplied to the primary self-resonant coil 330 that is magnetically coupled to the primary coil 320 by electromagnetic induction. The primary self-resonant coil 330 is an LC resonator having its own inductance and stray capacitance, and resonates with a secondary self-resonant coil 340 having the same resonance frequency as the primary self-resonant coil 330 via 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) transferred to the secondary self-resonant coil 340 is taken out by the secondary 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 coil 230 and the primary self-resonant coil 240 in FIG. 1 correspond to the primary coil 320 and the primary self-resonant coil 330 in FIG. 2, respectively, and the secondary self-resonant coil 110 and the secondary coil 120 in FIG. This corresponds to the secondary self-resonant coil 340 and the secondary 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. A curve k1 is a component inversely proportional to the distance from the wave source, and is referred to as a “radiating electric 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 “induced electric field”. The curve k3 is a component that is inversely proportional to the cube of the distance from the wave source, and is referred to as an “electrostatic field”.

  The “electrostatic field” is a region where the intensity of the electromagnetic wave suddenly decreases with the distance from the wave source. In the resonance method, energy (electric power) is utilized by using the near field (evanescent field) in which this “electrostatic field” is dominant. 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 field” is dominant, Energy (electric power) is transmitted to the resonator (secondary self-resonant coil). Since this “electrostatic field” does not propagate energy far away, the resonance method can transmit power with less energy loss than electromagnetic waves that transmit energy (electric power) by “radiant electric field” that propagates energy far away. it can.

  FIG. 4 is a diagram showing the electric field distribution (voltage distribution) of secondary self-resonant coil 110 and primary self-resonant coil 240 shown in FIG. Referring to FIG. 4, the horizontal axis indicates the distance from the center portion of the coil conducting wire constituting the self-resonant coil, and the vertical axis indicates the electric field of the coil conducting wire. As shown in FIG. 4, the closer to the end of the coil conductor, the higher the electric field and the maximum at the end. For example, when the transmitted power reaches a level of several hundred watts, a spark discharge occurs due to the electric field exceeding the dielectric breakdown limit at the end of the coil conductor. If the transmitted power becomes even higher, spark discharge can occur near the end of the coil conductor. The electric field at the center of the coil conductor is zero, and the sign of the electric field is inverted according to the resonance frequency.

  In this embodiment, the secondary self-resonant coil 110 and the primary self-resonant coil 240 are coated with an insulating resin in this embodiment where spark discharge can occur near the end of the coil conductor and in the vicinity of the end. The Then, based on the electric field distribution of the coil conductor shown in FIG. 4, the coil conductor is coated so that the thickness of the resin increases as it is closer to the end of the coil conductor.

  FIG. 5 is an enlarged view of the ends of the secondary self-resonant coil 110 and the primary self-resonant coil 240. Referring to FIG. 5, an insulating resin 420 is coated around the coil conductor 410 constituting the self-resonant coil. The coil conducting wire 410 is a highly conductive electric wire and is made of, for example, silver or copper. The resin 420 is made of, for example, Teflon (registered trademark), silicon, or the like, and is coated into a taper shape so that the thickness increases as the end of the coil conductive wire 410 is closer.

  The reason why the resin 420 is tapered so as to increase in thickness as it approaches the end of the coil conductor 410 is as follows. That is, as described above, when the transmission power increases, not only the coil end but also the voltage in the vicinity of the end can cause a spark discharge to occur, so that the end of the coil conductor 410 has insulating properties. This is because the thickness of the resin 420 is determined based on the electric field distribution of the coil conductor 410 shown in FIG.

  FIG. 6 is a diagram showing the thickness of the resin 420 over the entire length of the secondary self-resonant coil 110 and the primary self-resonant coil 240. In FIG. 6, secondary self-resonant coil 110 (or primary self-resonant coil 240) is linearly extended so that the change in thickness of resin 420 can be easily understood.

  Referring to FIG. 6, the resin 420 is coated in a tapered shape so that the thickness increases as it is closer to both ends of the coil conductor 410, and the resin 420 is not provided in a portion near the center of the coil conductor 410, Alternatively, it is thinly coated. As shown in FIG. 4, in the portion near the center of the coil conductor 410, the voltage of the coil conductor 410 is low and does not cause dielectric breakdown. The resin 420 is made thinner. Thereby, the amount of the resin 420 can be reduced, the weight of the coil can be reduced, and the heat dissipation of the coil can be secured.

  As described above, in this embodiment, in the secondary self-resonant coil 110 and the primary self-resonant coil 240, the insulating resin 420 is coated in a taper shape so that the thickness increases as the end of the coil conducting wire 410 is closer. Since it is processed, the limit value of dielectric breakdown increases as it approaches the end of the coil conductor 410. Therefore, according to this embodiment, it is possible to prevent the occurrence of spark discharge in secondary self-resonant coil 110 and primary self-resonant coil 240.

  In addition, the thickness of the resin 420 is not uniformly increased over the entire length of the coil conductor 410, but the thickness is increased as it is closer to the end of the coil conductor 410, so that the amount of resin can be reduced and the weight of the coil can be reduced. Can do. Moreover, the heat dissipation of a coil can also be ensured.

  In the above-described embodiment, the electric vehicle may be a hybrid vehicle further equipped with an engine as a power source in addition to the motor 170. The electric vehicle may be a fuel cell vehicle equipped with a fuel cell as a DC power source.

  In the above description, the power supplied from power supply device 200 is charged in power storage device 150. However, the present invention is also applicable to a vehicle that does not include the power storage device. That is, the present invention is also applicable to an electric vehicle that travels with a motor while receiving power from a power feeding device during traveling.

  In the above description, each of secondary self-resonant coil 110 and primary self-resonant coil 240 corresponds to an example of a “resonant coil” 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.

1 is an overall configuration diagram of a non-contact power feeding system according to an embodiment of the present 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 the figure which showed the electric field distribution of the secondary self-resonance coil and primary self-resonance coil which are shown in FIG. It is an enlarged view of the edge part of a secondary self-resonance coil and a primary self-resonance coil. It is the figure which showed the thickness of resin over the full length of a secondary self-resonance coil and a primary self-resonance coil.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Electric vehicle, 110, 340 Secondary self-resonant coil, 120, 350 Secondary coil, 130 Rectifier, 140 DC / DC converter, 150 Power storage device, 160 PCU, 170 Motor, 180 Vehicle ECU, 210 AC power supply, 220 High frequency power Driver, 230, 320 Primary coil, 240, 330 Primary self-resonant coil, 360 load, 410 coil conductor, 420 resin.

Claims (6)

A resonance coil that transmits power to or receives power from the coil by resonating with another coil via an electromagnetic field,
A coil conductor that electrically resonates at a predetermined resonance frequency;
A resonance coil comprising: an insulating resin coated on the coil conductor such that the thickness thereof increases as the end of the coil conductor is closer.   The resonance coil according to claim 1, wherein the thickness of the resin is determined according to an electric field distribution of the coil conductor.   The resonance coil according to claim 1, wherein the resin is coated in a tapered shape from a non-central portion to an end portion of the coil conductor. A primary coil that receives power from a power source;
A primary self-resonant coil that is fed by electromagnetic induction from the primary coil and generates an electromagnetic field;
A secondary self-resonant coil that receives power from the primary self-resonant coil by resonating with the primary self-resonant coil via the electromagnetic field;
A secondary coil that takes out the electric power received by the secondary self-resonant coil by electromagnetic induction;
A rectifier that rectifies the power extracted by the secondary coil and supplies the rectified power to a load
Each of the primary self-resonant coil and the secondary self-resonant coil is:
A coil conductor that electrically resonates at a predetermined resonance frequency;
A non-contact power feeding system including an insulating resin that is coated on the coil conductor such that the thickness increases as the end of the coil conductor is closer.   The contactless power feeding system according to claim 4, wherein the thickness of the resin is determined according to an electric field distribution of the coil conductor.   The non-contact power feeding system according to claim 4 or 5, wherein the resin is coated in a taper shape from a non-central portion to an end portion of the coil conducting wire.

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