JP5595895B2 - Resonant coil and non-contact power transmission device having the same - Google Patents

Description

  The present invention relates to a resonance coil that transmits power to a counterpart coil or receives power transmitted from the counterpart coil by a resonance phenomenon, and a non-contact power transmission apparatus having the resonance coil.

  In recent years, for example, charging of a secondary battery (hereinafter simply referred to as “battery”) included in an electric vehicle or the like is wireless (non-contact) that does not require physical connection such as plug connection in order to facilitate charging work. ) Is used.

  As such wireless power transmission technology, an electromagnetic induction method using an electromagnetic induction phenomenon, an electromagnetic wave transmission method using an electromagnetic wave, a resonance method using a resonance phenomenon, and the like are known. Among them, the resonance method is a technique for transmitting electric power by supplying AC power to the transmission resonance coil and causing the transmission resonance coil to resonate with the reception resonance coil disposed opposite to the transmission resonance coil via an electromagnetic field. It is possible to transmit large power of several kW between relatively distant places.

  However, when such a resonance-type wireless power transmission technology is applied to a system in which large power of several kW to several tens of kW is transmitted, such as a battery charging system of an electric vehicle, for example, as shown in FIG. When the resonance state is reached, a high voltage is generated at or near the end of the coil wire wound in the tubular shape of the resonance coil, and a dielectric breakdown occurs with a grounded case that accommodates the resonance coil, resulting in a spark. There were problems such as the occurrence of discharge. And the technique which solves such a problem is disclosed by patent document 1, for example.

  As shown in FIG. 7, the resonance coil 901 disclosed in Patent Literature 1 includes a coil conductor 910 and an insulating resin 920 as a covering member. The coil conducting wire 910 is wound in a tubular shape a plurality of times. And since this insulating resin 920 is coated on the coil conductor 910 so that the thickness increases as it approaches the end 910a in the longitudinal direction of the coil conductor 910, the dielectric strength at the end 910a of the coil conductor 910 is increased. To prevent spark discharge. The coil conductor 910 of the resonance coil 901 is provided with a certain inter-conductor gap between the winding portions of the coil conductor 910 to prevent spark discharge due to dielectric breakdown between the winding portions of the coil conductor 910. It was out.

  Such a resonance coil 901 is used for, for example, a battery charging system of an electric vehicle, and therefore, downsizing is required for improving fuel efficiency, securing a vehicle interior space, and effectively using a charging area. However, the above-described resonance coil 901 is coated so that the thickness of the resin 920 increases as it approaches the end 910a in the longitudinal direction of the coil conductor 910, and is not provided in the center in the longitudinal direction. Alternatively, it is thinly coated, so that the dielectric breakdown resistance (dielectric strength) in the axial central portion of the coil conductor 910 is low, and the gap between the conductors between the winding portions cannot be reduced. Could not be miniaturized. As a technique for solving such a problem, by covering the entire coil conductor 910 with a covering member having a uniform thickness, the dielectric strength between the winding portions of the coil conductor 910 is improved, and the coil conductor 910 A configuration in which the gap is made small is known.

JP 2010-73885 A

  However, in the resonance coil having the above-described configuration, the thickness of the covering member that covers the coil conductor is the highest even though the potential difference generated between the winding portions of the coil conductor differs depending on the location of the coil conductor as can be seen from FIG. Since it is determined uniformly according to the large potential difference, the coating member becomes thicker than necessary at the portion where the potential difference is lower than this, and it has excessive dielectric strength. As a result, the manufacturing cost increases.

  The present invention aims to solve the above problems. That is, an object of the present invention is to provide a small and inexpensive resonant coil that does not cause dielectric breakdown between coil conductors and a non-contact power transmission device including the same.

  As a result of repeated investigations on the configuration of the resonance coil in order to achieve both reduction in size and cost of the resonance coil, the present inventor has produced different potential differences between the winding portions of the coil conductor. By providing a covering member having an appropriate thickness according to the potential difference between them, the present inventors have found that it is possible to realize a low cost while having a small shape, and completed the present invention.

  In order to achieve the above object, the invention described in claim 1 is a resonance coil that transmits electric power to a counterpart coil by a resonance phenomenon or receives electric power transmitted from the counterpart coil. A coil conductor having a thickness corresponding to a potential difference generated between the one winding portion and another winding portion adjacent to the one winding portion. A resonance coil is provided with a member.

  The invention described in claim 2 is the invention described in claim 1, wherein the coil conductor is wound in a tubular shape a plurality of times, and a thickness of an axially central portion of the coil conductor in the covering member. Is larger than the thickness of both end portions in the axial direction of the coil conductor in the covering member.

  In order to achieve the above object, a third aspect of the present invention includes a transmission resonance coil that transmits power by a resonance phenomenon, and a reception resonance coil that receives power transmitted from the transmission resonance coil. In the contact power transmission device, at least one of the transmission resonance coil and the reception resonance coil is the resonance coil according to claim 1 or 2, wherein the contact power transmission device is a contactless power transmission device.

  According to the first aspect of the present invention, the coil conductor has a coil conductor wound a plurality of times, and the coil conductor has one winding part and another one adjacent to the one winding part. Since a covering member having a thickness corresponding to the potential difference generated between the winding portion and the winding portion is provided, for example, when the thickness of the covering member provided on the coil conductor is uniform, a part of the covering member is excessive. In the present invention, an excessive dielectric strength is obtained by providing a covering member with an appropriate thickness by providing a covering member having a thickness according to the potential difference generated between the winding portions of the coil conductor. Therefore, it is possible to provide a small and inexpensive resonance coil that does not cause dielectric breakdown between coil conductors.

  According to the second aspect of the present invention, the coil conductor is wound in a tubular shape a plurality of times, and the thickness of the central portion of the coil conductor in the covering member in the axial direction is larger than the thickness of both end portions in the axial direction. In a resonance coil having a characteristic that a potential difference generated between each winding portion of a coil conductor is large at the axial center portion of the tubular coil conductor and becomes small at both ends, a small and inexpensive resonance without insulation breakdown between the coil conductors. Coil can be provided.

  According to the invention described in claim 3, since at least one of the transmission resonance coil and the reception resonance coil is the resonance coil described in claim 1 or 2, by using a small and inexpensive resonance coil, A small and inexpensive contactless power transmission device can be provided.

It is a perspective view which shows one Embodiment of the resonance coil of this invention. (A) is sectional drawing which follows the longitudinal direction in the state which extended the coil conducting wire which the resonance coil of FIG. 1 has extended straight, (b) is sectional drawing which follows the X1-X1 line of (a). (C) is sectional drawing which follows the X2-X2 line | wire of (a). It is explanatory drawing which shows the structure of the wireless power transmission apparatus which concerns on one Embodiment of the non-contact power transmission apparatus of this invention. FIG. 4 is a block diagram of the wireless power transmission device of FIG. 3. It is explanatory drawing which shows the principle of a resonance-type electric power transmission system. It is a figure which shows typically the voltage distribution in the resonance state in a coil conducting wire. It is a partial expanded sectional view which shows the structure of the conventional resonance coil.

(One Embodiment of Resonance Coil)
Hereinafter, an embodiment of a resonance coil of the present invention will be described with reference to FIGS.

  The resonance coil is used to transmit power to or receive power transmitted from the counterpart coil by using a resonance phenomenon.

  The resonance coil according to the present invention shown in each drawing (indicated by reference numeral 50 in the drawings) has a coil conductor 51 and a covering member 53.

  As shown in each drawing, the coil conductor 51 is, for example, an air-core spiral coil having a diameter D of 600 mm and a length L of 200 mm, in which a copper wire having a diameter of 5 mm is wound around a tubular (solenoid) a plurality of times (n times). It is. The coil conductor 51 is provided with winding portions 55 [1] to 55 [n] which are a plurality of circular portions (one turn). Between one winding portion 55 [k] of the coil conductor and another winding portion 55 [k + 1] (k: 1 to n−1) adjacent thereto (hereinafter simply referred to as between the winding portions 55), A certain gap G (that is, a gap) between the conductors is provided. The “constant inter-conductor gap G” means that the inter-conductor gaps G are the same or substantially the same.

  FIG. 6 shows the voltage distribution of the coil conductor 51 in the resonance state. As is apparent from FIG. 6, the potential difference between the unit distances in the coil conductor 51 (ie, the slope of the graph) is larger at the central portion in the longitudinal direction of the coil conductor 51 (ie, the origin of the graph). It gets smaller as it gets closer to the part. That is, the coil conductor 51 wound in a tubular shape has a different potential difference between the winding portions 55 depending on the location, and specifically, between the winding portions 55 in the central portion in the axial direction (that is, the length L direction). The potential difference is larger than the potential difference between the winding portions 55 at both axial ends.

  The covering member 53 is made of, for example, a synthetic resin having a high withstand voltage such as PI (polyimide) or PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), and the entire surface of the coil conductor 51 is formed. It is provided so as to cover. The dielectric breakdown voltage (AC) of the covering member 53 is about 15 to 20 [kV / mm] in PI and about 150 [kV / mm] in PFA, while the dielectric breakdown voltage (AC) of air. Is about 3 [kV / mm], and by providing such a covering member 53, the gap G between the conductors can be further reduced.

  The structure of the covering member 53 is shown in FIGS. FIG. 2A is a cross-sectional view along the longitudinal direction of the coil conductor 51 that is straightened, and FIG. 2B is a central portion in the longitudinal direction of the coil conductor 51, that is, a tube that is wound a plurality of times. FIG. 2C is a cross-sectional view of a portion that is an axially central portion of the coil conductor 51 in a state where the coil conductor 51 is formed, and FIG. 2C is a coil conductor in a state where one end in the longitudinal direction of the coil conductor is wound. It is sectional drawing of the part used as the axial direction both ends of 51.

  The covering member 53 has a minimum thickness according to the potential difference between the winding portions 55, that is, even when this potential difference occurs, the covering member 53 has a minimum thickness necessary to prevent dielectric breakdown between the winding portions 55. It is formed as follows. The thickness of the covering member 53 is determined according to the voltage distribution of the coil conductor 51 in the resonance state.

  That is, the covering member 53 has a thickness at the center in the longitudinal direction (that is, the center in the axial direction of the coil conductor 51) as shown in FIGS. 2A to 2C in accordance with the characteristics of the coil conductor 51. The thickness is formed so that the thickness gradually decreases toward both ends in the longitudinal direction (that is, both ends in the axial direction of the coil conductor 51). In other words, the covering member 53 is provided such that the thickness of the coil conducting wire 51 at the central portion in the axial direction is larger than the thickness at both axial end portions.

  In the present embodiment, the covering member 53 is formed so that the thickness of the central portion in the axial direction of the coil conducting wire 51 is larger than the thickness of both end portions in the axial direction. On the other hand, in the case of other configurations, for example, when the thickness of the covering member 53 is made uniform over the entire length of the coil conducting wire 51, the thickness is the winding portion 55 at the axially central portion of the coil conducting wire 51. Therefore, the thickness of the covering member 53 becomes excessive at both ends in the axial direction of the coil conducting wire 51, resulting in waste.

  And according to this embodiment, about the coating | coated member 53, the thickness difference is made small in the axial direction both ends of the coil conducting wire 51 where the electrical potential difference between the winding parts 55 is comparatively low, and the electrical potential difference between the winding parts 55 is made. In the axially central portion of the relatively high coil conductor 51, by increasing the thickness, a covering member 53 having a thickness corresponding to the potential difference between the winding portions 55 is provided, thereby reducing the size and cost. Both are compatible.

  As described above, according to the present invention, the coil conductor 51 has the coil conductor 51 that is wound a plurality of times and is provided with a constant gap G between the winding portions 55. Since the covering member 53 having a thickness corresponding to the potential difference generated between the turning portion 55 [k] and another winding portion 55 [k + 1] adjacent thereto is provided, for example, the covering member provided on the coil conductor 51 When the thickness of 53 is made uniform, a part of the covering member 53 will have an excessive dielectric strength. In the present invention, it is adjusted to the potential difference generated between the winding portions 55 of the coil conductor 51. By providing the covering member 53 with a thickness, it is possible to eliminate the portion having an excessive dielectric strength by setting the covering member 53 to an appropriate thickness, and realize a small and inexpensive resonance coil without insulation breakdown between the coil conductors 51. it can.

  In addition, the coil conductor 51 is wound in a tubular shape a plurality of times, and the thickness of the central portion of the coil conductor 51 in the covering member 53 in the axial direction is larger than the thickness of both end portions in the axial direction. In a resonance coil having a characteristic that a potential difference generated between the portions 55 is large at the axial center portion of the tubular coil conductor 51 and becomes small at both ends, a small and inexpensive resonance coil without dielectric breakdown between the coil conductors 51 is realized. it can.

  In the present embodiment, the thickness of the central portion in the axial direction of the coil conductor 51 in the covering member 53 is formed to be larger than the thickness of both end portions in the axial direction. However, the present invention is not limited to this. Unless it is contrary to the object of the present invention, a covering member having a thickness corresponding to a potential difference generated between one winding portion 55 [k] of the coil conductor 51 and another winding portion 55 [k + 1] adjacent thereto. What is provided is that 53 is provided.

  Moreover, in this embodiment, although the fixed gap G between conductors was provided between each winding part 55 of the coil conductor 51, it is not limited to this. For example, the inter-conductor gaps G may be different from each other, such as adjusting the inter-conductor gap G together with the thickness of the covering member 53 in accordance with the potential difference between the winding portions 55.

  Moreover, although the coil conducting wire 51 of the present embodiment has been wound a plurality of times in a tubular shape, the present invention is not limited thereto. For example, the coil conducting wire 51 is wound a plurality of times in a flat plate shape. A flat spiral coil or the like may be used, and the shape of the coil conducting wire 51 is arbitrary as long as the object of the present invention is not violated.

(One Embodiment of Non-contact Power Transmission Device)
Next, a wireless power transmission device according to an embodiment of the non-contact power transmission device of the present invention provided with the above-described resonance coil will be described with reference to FIGS.

  FIG. 3 is an explanatory diagram showing the configuration of the wireless power transmission device according to the embodiment of the present invention. As shown in the figure, a wireless power transmission device 10 according to the present embodiment includes a power receiving device 12 provided in an electric vehicle 5 and a power feeding device 11 that supplies AC power to the power receiving device 12. The AC power output from the power feeding device 11 is transmitted to the power receiving device 12 in a non-contact (wireless) manner. The power feeding device 11 includes a communication coil 24 for power transmission. When AC power is supplied to the communication coil 24, the AC power is supplied to the power reception communication coil 31 provided in the power receiving device 12. Is transmitted to.

  The power receiving device 12 provided in the electric vehicle 5 includes a power receiving communication coil 31 that approaches the power transmitting communication coil 24 and a rectifier 33 when the electric vehicle 5 is placed at a predetermined position of the power feeding device 11 during charging. And. Furthermore, a battery 35 charged with DC power, a DC / DC converter 42 that steps down the voltage of the battery 35 and supplies it to the sub-battery 41, an inverter 43 that converts output power of the battery 35 into AC power, A motor 44 driven by AC power output from the inverter 43 is provided.

  FIG. 4 is a block diagram of the wireless power transmission device 10 according to the embodiment of the present invention, which includes a power feeding device 11 and a power receiving device 12 mounted on the electric vehicle 5.

  The power supply apparatus 11 is amplified by a carrier oscillator 21 that outputs a carrier signal for power transmission, a power amplifier 23 that amplifies the carrier signal (that is, AC power) output from the carrier oscillator 21, and the power amplifier 23. A communication coil 24 that outputs AC power is provided. As will be described later, the communication coil 24 includes a feeding coil (primary coil) L1 and a transmission resonance coil X1. And the resonance coil 50 mentioned above is used as this transmission resonance coil X1.

  The carrier oscillator 21 outputs, for example, AC power having a frequency of 1 to 100 [MHz] as an AC signal for power transmission.

  The power amplifier 23 amplifies the AC power output from the carrier transmitter 21. Then, the amplified AC power is output to the communication coil 24. The communication coil 24 cooperates with the communication coil 31 provided in the power receiving device 12 and wirelessly transmits AC power to the communication coil 31 by a resonance type power transmission method. The resonance type power transmission method (that is, the resonance method) will be described later.

  The power receiving device 12 rectifies the AC power received by the communication coil 31 and receives the AC power transmitted from the power transmission communication coil 24, and rectifies the DC voltage. And a rectifier 33 to be generated. In addition, a battery 35 that supplies electric power to the vehicle driving motor 44 (see FIG. 3) is provided, and the battery 35 is charged by DC power output from the rectifier 33.

  As will be described later, the communication coil 31 includes a power receiving coil (primary coil) L2 and a receiving resonance coil X2. The above-described resonance coil 50 is used as the reception resonance coil X2.

  Next, the resonance type power transmission method will be described. FIG. 5 is an explanatory diagram showing the principle of the resonant power transmission method. As shown in the figure, the power feeding device 11 is provided with a power feeding coil L1 and a transmission resonance coil X1 (that is, a resonance coil 50) that is disposed concentrically and in proximity to the power feeding coil L1. Note that the power supply coil L1 and the transmission resonance coil X1 constitute the communication coil 24 shown in FIGS. In addition, the power receiving device 12 is provided with a power receiving coil L2 and a receiving resonance coil X2 (that is, a resonance coil 50) disposed concentrically and in proximity to the power receiving coil L2. The receiving coil L2 and the receiving resonance coil X2 constitute the communication coil 31 shown in FIGS.

  When a primary current is passed through the feeding coil L1, an induced current flows through the transmission resonance coil X1 by electromagnetic induction, and the transmission resonance coil X1 resonates due to the inductance Ls and the stray capacitance Cs of the transmission resonance coil X1. Resonates at a frequency ωs (= 1 / √Ls · Cs). Then, the reception resonance coil X2 on the power receiving device 12 side provided near the transmission resonance coil X1 resonates at the resonance frequency ωs, and a secondary current flows through the reception resonance coil X2. Further, a secondary current flows through the power receiving coil L2 close to the receiving resonance coil X2 due to electromagnetic induction.

  With the above operation, power can be transmitted from the power feeding device 11 to the power receiving device 12 wirelessly.

  Next, the operation of the wireless power transmission device of the present invention shown in FIGS. 3 and 4 will be described. As shown in FIG. 3, the electric vehicle 5 is placed at a predetermined position of the power feeding device 11, and the communication coil 24 provided in the power feeding device 11 and the communication coil 31 provided in the power receiving device 12 of the electric vehicle 5 are opposed to each other. Then, the battery 35 can be charged.

  When charging is started, AC power having a frequency of about 1 to 100 [MHz] is output from the carrier oscillator 21 shown in FIG.

  Then, the AC power output from the carrier transmitter 21 is amplified by the power amplifier 23. The amplified AC power is transmitted to the power receiving device 12 through the communication coils 24 and 31 based on the principle of the resonance power transmission described above.

  The AC power transmitted to the power receiving device 12 is output from the communication coil 31 to the rectifier 33.

  The rectifier 33 rectifies AC power and converts it into DC power of a predetermined voltage, supplies this power to the battery 35, and charges the battery 35. Thereby, the battery 35 can be charged.

  As described above, according to the present invention, since the above-described resonance coil 50 is used as the transmission resonance coil X1 and the reception resonance coil X2, the resonance coil 50 is wound a plurality of times and is constant between the winding portions 55. The coil conductor 51 is provided with a gap G between the conductors, and the coil conductor 51 has a space between one winding portion 55 [k] and another winding portion 55 [k + 1] adjacent thereto. Since the covering member 53 having a thickness corresponding to the potential difference generated in the first and second portions is provided, the covering member 53 can be made to have an appropriate thickness so that a portion having excessive dielectric strength can be eliminated, and the transmission resonance coil X1 and the reception resonance coil X2 Can be miniaturized at low cost, and therefore a small and inexpensive non-contact power transmission device can be provided.

  In the present embodiment, the resonance coil 50 described above is used for both the transmission resonance coil X1 and the reception resonance coil X2. However, the present invention is not limited to this, and at least one of the transmission resonance coil X1 and the reception resonance coil X2 is used. Any one using the resonance coil 50 may be used.

  In addition, embodiment mentioned above only showed the typical form of this invention, and this invention is not limited to embodiment. That is, various modifications can be made without departing from the scope of the present invention.

5 Electric vehicle 10 Wireless power transmission device (non-contact power transmission device)
50 Resonant Coil 51 Coil Conductor 53 Covering Member 55 Winding Part G Conductor Gap G (Spacing Between Winding Parts)
X1 Transmission resonance coil (resonance coil)
X2 receiving resonance coil (resonance coil)

Claims (3)

A resonance coil that transmits power to a counterpart coil by a resonance phenomenon or receives power transmitted from the counterpart coil,
Having a coil wire wound several times; and
The coil conductor is provided with a covering member having a thickness corresponding to a potential difference generated between the one winding portion and another winding portion adjacent to the one winding portion. Resonant coil. The coil conductor is wound into a tube a plurality of times;
2. The resonance coil according to claim 1, wherein a thickness of an axially central portion of the coil conductor in the covering member is larger than thicknesses of both end portions in the axial direction of the coil conductor of the covering member. In a non-contact power transmission apparatus having a transmission resonance coil that transmits power by a resonance phenomenon, and a reception resonance coil that receives power transmitted from the transmission resonance coil,
The contactless power transmission device according to claim 1, wherein at least one of the transmission resonance coil and the reception resonance coil is the resonance coil according to claim 1.

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