JP6365110B2 - Coil unit - Google Patents

Description

  The present invention relates to a coil unit used in a non-contact power transmission apparatus.

  The non-contact power transmission technology uses the coupling of electric field, magnetic field, electromagnetic wave, etc. between the primary (power transmission) coil and the secondary (power reception) coil that are opposed to each other. This is a technology for transmitting non-contact to the secondary coil. There are several types of transmission technologies. Among them, the magnetic field resonance method using the coupling of magnetic fields and using the power transmission coil unit and the power reception coil unit as LC resonance circuits and matching the resonance frequencies of both coil units is a short to medium distance. The system is attracting attention as a method that can perform high-power transmission with high efficiency.

  When the magnetic resonance type non-contact power transmission technology is applied to a charging device that requires high power transmission such as an electric vehicle, heat generation due to loss becomes a serious problem, so the coil unit itself has low loss and high power transmission. Efficiency is required.

  In response to such a demand, for example, in Patent Document 1, the coil core has a flat structure in which the coil is wound in a spiral shape, and the magnetic core provided with the coil is a ferrite core having a flat plate shape. Non-contact power feeding devices have been proposed. In this non-contact power feeding device, the coil and the magnetic core are arranged and adjusted with the area as a guideline to minimize the overall magnetic resistance, thereby preventing the magnetic flux formed. As a result, the power loss is reduced, the high output is secured, and the power supply efficiency such as the charging efficiency is improved.

JP 2010-119187 A

  However, in the technique disclosed in Patent Document 1, since the magnetic body is disposed close to the coil as a core, the loss of the coil increases due to a phenomenon called a mirror image effect, and as a result, the heat generation of the coil unit increases. There was a problem to do. Here, the mirror image effect means that when a magnetic material is brought close to a conducting wire through which an alternating current flows, a mirror-symmetric conducting wire having a magnetic surface as a symmetry plane exists and the magnetic flux counteracts as if the magnetic flux cancels each other. This is a phenomenon in which alternating current resistance is increased by inducing electric power and reducing the current density inside the conductor in a portion close to the magnetic body.

  Further, in the technique disclosed in Patent Document 1, although the inductance between the coils can be improved by minimizing the magnetic resistance, the AC resistance increases as described above. There is a possibility that the Q value of the coil that contributes to the coil hardly changes or may decrease depending on the case, and it is difficult to greatly improve the Q value of the coil, and there is a problem that the efficiency is insufficient. Here, the Q value of the coil is an amount represented by the equation Q = ωL / R, and the product of the angular velocity ω of the transmission frequency used for power transmission and the inductance of the coil unit is divided by the AC resistance at the transmission frequency. It is the value.

  The present invention has been made in view of such a problem, and suppresses an increase in AC resistance when a magnetic material is disposed close to the coil, thereby greatly improving the Q value of the coil, thereby achieving high efficiency and low loss. The purpose is to obtain a coil unit.

  As a result of intensive research conducted by the present inventors in order to solve the above-mentioned problems, the distance between the strands constituting the winding formed by twisting a plurality of insulation-coated conductors as the coil conductor, and the magnetic body Since it was newly found that the increase in AC resistance can be suppressed and further the AC resistance can be reduced depending on the positional relationship, the present invention has been completed.

  A coil unit according to the present invention includes a rod-like or plate-like magnetic body, and a winding wound on the surface of the magnetic body, and the winding includes a primary strand obtained by twisting a plurality of insulation-coated conductors. , And a secondary strand obtained by twisting a plurality of primary strands, and a gap between the first portion having a wide interval between the strands constituting the outermost periphery of the winding is narrow. It has the 2nd part, and the 2nd part is located in the surface side of a magnetic body rather than the 1st part, It is characterized by the above-mentioned.

  According to the present invention, the winding includes a primary strand obtained by twisting a plurality of insulation-coated conductors and a secondary strand obtained by twisting a plurality of primary strands, and the outermost periphery of the winding. The first portion has a wide space between the strands and the second portion has a narrow space between the strands, and the second portion is located closer to the magnetic body than the first portion. Therefore, an increase in AC resistance due to the counter electromotive force generated by the mirror image effect of the magnetic material can be most effectively suppressed, and a reduction in loss of the coil unit can be realized. Moreover, since the coil unit according to the present invention can suppress only the AC resistance without reducing the inductance of the coil, the Q value of the coil can be greatly improved. As a result, the transmission efficiency can be increased.

  Preferably, the size of the total area of the cross sections of the windings is 200 times or more with respect to the size of the cross-sectional area per one of the plurality of insulating coated conductors. In this case, the difference in spacing between the strands of the first part and the second part constituting the outermost periphery of the winding becomes sufficiently large, and an increase in AC resistance due to the mirror image effect can be further suppressed. The Q value of the coil can be further greatly improved.

  ADVANTAGE OF THE INVENTION According to this invention, the increase in alternating current resistance at the time of arrange | positioning a magnetic body close to a coil can be suppressed, Q value of a coil can be improved significantly, and a highly efficient and low-loss coil unit can be provided.

It is a system configuration figure showing a non-contact power transmission device with which a coil unit concerning a suitable embodiment of the present invention is applied with a load. It is sectional drawing of the coil unit which concerns on suitable embodiment of this invention. It is a schematic diagram which shows the twisting structure in the coil | winding of the coil unit which concerns on suitable embodiment of this invention. FIG. 3 is a plan view of a winding viewed from the direction of arrow A in FIG. 2 in a coil unit according to a preferred embodiment of the present invention. FIG. 3 is a plan view of a winding viewed from the direction of arrow B in FIG. 2 in a coil unit according to a preferred embodiment of the present invention. It is the schematic cross section which looked at the coil | winding of the structure which twisted the insulation coating conductor 3 steps in the direction orthogonal to the extension direction of a coil | winding. It is sectional drawing of the coil unit which concerns on the modification corresponding to sectional drawing of the coil unit which concerns on suitable embodiment of this invention shown in FIG. In the coil unit which concerns on a modification, it is a top view of the coil | winding seen from the arrow C direction of FIG. In the coil unit which concerns on a modification, it is a top view of the coil | winding seen from the arrow D direction of FIG. In the coil unit which concerns on a modification, it is a top view of the coil | winding seen from the arrow E direction of FIG. In the coil unit which concerns on a modification, it is a top view of the coil | winding seen from the arrow F direction of FIG. FIG. 3 is a plan view of a winding of a coil unit according to Comparative Example 1, corresponding to a plan view of the winding as viewed from the direction of arrow A in FIG. 2. FIG. 3 is a plan view of a winding of a coil unit according to Comparative Example 1, corresponding to a plan view of the winding viewed from the direction of arrow B in FIG. 2. It is a measurement result of the inductance L of Example 1 and Comparative Examples 1 and 2. It is a measurement result of equivalent series resistance value Rs of Example 1 and Comparative Examples 1 and 2. It is a measurement result of Q value of Example 1 and Comparative Examples 1 and 2. It is a measurement result of the inductance L of Example 2 and Comparative Examples 3 and 4. 4 shows the measurement results of equivalent series resistance values Rs of Example 2 and Comparative Examples 3 and 4. FIG. It is a measurement result of Q value of Example 2 and Comparative Examples 3 and 4.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  First, an overall configuration of a non-contact power transmission apparatus S1 to which a coil unit according to a preferred embodiment of the present invention is applied will be described with reference to FIG. FIG. 1 is a system configuration diagram showing a contactless power transmission device to which a coil unit according to a preferred embodiment of the present invention is applied together with a load. In addition, the coil unit which concerns on suitable embodiment of this invention is applicable to any of the power transmission coil unit and power receiving coil unit in a non-contact electric power transmission apparatus.

  As shown in FIG. 1, the non-contact power transmission device S1 includes a power transmission device Ut and a power reception device Ur.

  The power transmission device Ut includes a power source PW, an inverter INV, and a power transmission side resonance unit Rtu. The power receiving device Ur includes a rectifier circuit DB and a power receiving side resonance unit Rru.

  First, the configuration of the power transmission device Ut will be described. The power source PW supplies DC power to an inverter INV described later. The power source PW is not particularly limited as long as it outputs DC power. A DC power source rectified and smoothed from a commercial AC power source, a secondary battery, a DC power source generated by photovoltaic power, or a switching power source device such as a switching converter, etc. Is mentioned.

  The inverter INV has a function of converting input DC power supplied from the power source PW into AC power. In the present embodiment, the inverter INV converts the input DC power supplied from the power source PW into AC power, and supplies the AC power to a power transmission coil unit Ltu and a power transmission side resonance capacitor unit Ctu, which will be described later, which are resonance parts. The inverter INV is composed of a switching circuit in which a plurality of switching elements are bridge-connected. Examples of the switching elements constituting the switching circuit include elements such as MOS-FETs (Metal Oxide Semiconductor-Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors).

  As shown in FIG. 1, the power transmission side resonance unit Rtu includes a power transmission coil unit Ltu and a power transmission side resonance capacitor unit Ctu. Specifically, the power transmission side resonance unit Rtu constitutes an LC resonance circuit formed by the power transmission coil unit Ltu and the power transmission side resonance capacitor unit Ctu. Therefore, by configuring the resonance frequency of the power transmission side resonance unit Rtu to be substantially equal to the resonance frequency of the power reception side resonance unit Rru, which will be described later, it is possible to realize magnetic field resonance type power transmission.

  The power transmission coil unit Ltu has a function of transmitting AC power supplied from the inverter INV to the power receiving coil unit Lru described later. When the non-contact power transmission device S1 according to the present embodiment is applied to a power supply facility for a vehicle such as an electric vehicle, the power transmission coil unit Ltu is disposed in the ground or in the vicinity of the ground.

  The power transmission side resonance capacitor unit Ctu has a function of adjusting the resonance frequency so that the resonance frequency of the power transmission side resonance unit Rtu becomes substantially equal to the resonance frequency of the power reception side resonance unit Rru described later. The power transmission side resonance capacitor unit Ctu may be connected in series to the power transmission coil unit Ltu, may be connected in parallel, or may be a combination of series connection and parallel connection.

  Next, the configuration of the power receiving device Ur will be described. As shown in FIG. 1, the power reception side resonance unit Rru includes a power reception coil unit Lru and a power reception side resonance capacitor unit Cru. Specifically, the power reception side resonance unit Rru constitutes an LC resonance circuit formed by the power reception coil unit Lru and the power reception side resonance capacitor unit Cru. Therefore, by configuring the resonance frequency of the power receiving side resonance unit Rru to be substantially equal to the resonance frequency of the power transmission side resonance unit Rtu, it is possible to realize magnetic field resonance type transmission.

  The power receiving coil unit Lru has a function of receiving AC power transmitted from the power transmitting coil unit Ltu. In addition, when the non-contact power transmission device S1 according to the present embodiment is applied to a power supply facility for a vehicle such as an electric vehicle, the power receiving coil unit Lru is mounted on the lower portion of the vehicle.

  The power reception side resonance capacitor unit Cru has a function of adjusting the resonance frequency so that the resonance frequency of the power transmission side resonance unit Rtu is substantially equal to the resonance frequency of the power reception side resonance unit Rru. The power receiving side resonance capacitor unit Cru may be connected in series to the power receiving coil unit Lru, may be connected in parallel, or may be a combination of series connection and parallel connection.

  The rectifier circuit DB has a function of rectifying the AC power received by the power receiving coil unit Lru into DC power. Examples of the rectifier circuit DB include a conversion circuit having a full-wave rectification function using a diode bridge and a power smoothing function using a capacitor and a three-terminal regulator. The DC power rectified by the rectifier circuit DB is output to the load R. Here, as the load R, when the non-contact power transmission device S1 according to the present embodiment is applied to a power supply facility for a vehicle such as an electric vehicle, a secondary battery or a rotating machine included in the vehicle may be used. When the load R is an AC rotating machine, an inverter (not shown) is added between the rectifier circuit DB of the non-contact power receiving device Ur and the load R so that AC power is supplied to the AC rotating machine. There is.

  By providing such a configuration, the power transmission coil unit Ltu and the power receiving coil unit Lru are opposed to each other, thereby realizing a non-contact power transmission device S1 that transmits power in a non-contact manner.

  Next, the configuration of the coil unit according to a preferred embodiment of the present invention applied to the above-described power transmission coil unit Ltu or power reception coil unit Lru will be described in detail.

  With reference to FIGS. 2-4, the structure of coil unit Lu1 which concerns on preferred embodiment of this invention is demonstrated. FIG. 2 is a cross-sectional view of a coil unit according to a preferred embodiment of the present invention. FIG. 3 is a schematic diagram showing a twisted structure in a winding of a coil unit according to a preferred embodiment of the present invention. FIG. 4A is a plan view of the winding as seen from the direction of arrow A in FIG. 2 in the coil unit according to the preferred embodiment of the present invention. FIG. 4B is a plan view of the winding as seen from the direction of arrow B in FIG. 2 in the coil unit according to the preferred embodiment of the present invention. 4A and 4B, the magnetic body F1 is omitted for convenience of explanation.

  As shown in FIG. 2, the coil unit Lu1 includes a magnetic body F1 and a coil C1. The magnetic body F1 is a rod-shaped or plate-shaped magnetic body. In the present embodiment, the magnetic body F1 has a substantially rectangular parallelepiped shape, and the outer surfaces thereof are substantially rectangular first and second main faces F1a and F1b facing each other, and the first and second opposing faces. It has a second side surface (not shown) and opposed first and second end faces F1c, F1d. The first and second side surfaces extend in the long side direction of the first and second main surfaces F1a and F1b so as to connect the first and second main surfaces F1a and F1b. The first and second end faces F1c, F1d extend in the short side direction of the first and second main faces F1a, F1b so as to connect the first and second main faces F1a, F1b. Further, when the coil unit Lu1 is applied to the power transmission coil unit Ltu or the power reception coil unit Lru, the long side directions of the first and second main surfaces F1a and F1b of the magnetic body F1 are between the power transmission coil unit Ltu and the power reception coil unit Lru. It will be arrange | positioned so that it may correspond to the direction orthogonal to an opposing direction. Still further, the magnetic body F1 is arranged to be separated from a coil C1 to be described later, and the separation distance between the magnetic body F1 and the coil C1 to be described later is an insulation distance necessary between them or a magnetic body. F1 is appropriately set based on a preferable effect of reducing the magnetic resistance exerted on the coil C1 described later. Such a magnetic body F1 is preferably made of a material having a relatively high relative permeability, and examples thereof include ferrite.

  The coil C1 is a flat spiral coil having a substantially square shape, and is formed by winding a winding W1 on the surface of the magnetic body F1. In the present embodiment, the coil C1 has a winding W wound around the first main surface F1a of the magnetic body F1. That is, the axial direction of the coil C1 is parallel to the opposing direction of the power transmission coil unit Ltu and the power reception coil unit Lru, which is a direction orthogonal to the long side direction of the first and second main surfaces F1a and F1b of the magnetic body F1. It becomes. Here, when the coil unit Lu1 is applied to the power transmission coil unit Ltu, the coil C1 is disposed closer to the power reception coil unit Lru than the magnetic body F1 in the facing direction of the power transmission coil unit Ltu and the power reception coil unit Lru. On the other hand, when the coil unit Lu1 is applied to the power reception coil unit Lru, the coil C1 is disposed closer to the power transmission coil unit Ltu than the magnetic body F1 in the facing direction of the power transmission coil unit Ltu and the power reception coil unit Lru. In other words, the magnetic body F1 is disposed on the side opposite to the power transmission surface of the coil C1 during power transmission. With such a configuration, when the winding W1 of the coil C1 is viewed in cross section, a part of the outer peripheral surface of the winding W1 is close to the first main surface F1a of the magnetic body F1, and a part of the outer peripheral surface of the winding W1. The (remaining part) is arranged so as to be away from the first main surface F1a of the magnetic body F1. The number of turns of the coil C1 is appropriately set based on a separation distance between the coils facing each other during power transmission, a desired power transmission efficiency, and the like.

  As shown in FIG. 3, the winding W <b> 1 is formed by twisting a plurality of insulating coated conductors 302 in which a conductor 301 is covered with an insulating material 300. Specifically, the winding W <b> 1 includes a primary strand 303 in which a plurality of insulation-coated conductors 302 are twisted and a secondary strand 304 in which a plurality of primary strands 303 are twisted. That is, the winding W1 has a structure in which the insulating coated conductor 302 is twisted in multiple stages. The conductor 301 constituting the insulating coated conductor 302 is preferably copper, aluminum, or an alloy containing these as a main component, and a laminate of these is also preferable. Moreover, as the insulating material 300 which comprises the insulation coating conductor 302, it is preferable in it being urethane type resin and imide type resin.

  Further, as shown in FIGS. 4a and 4b, the winding W1 includes a first portion 400 having a large interval between the strands constituting the outermost periphery of the winding W1 and a second interval having a small interval between the strands. It has a portion 401. In the present embodiment, the strand that forms the outermost periphery of the winding W1 corresponds to the primary strand 303. In the first portion 400, as shown in FIG. 4a, the interval between the primary strands 303 constituting the outermost periphery of the winding W1 is wide. On the other hand, in the second portion 401, as shown in FIG. 4b, the interval between the primary strands 303 constituting the outermost periphery of the winding W1 is narrow. Specifically, in FIG. 4 a, the center line 405 with respect to the width of one primary strand 303 of the adjacent primary strand 303 and the center line 406 with respect to the width of the other primary strand 303 are respectively orthogonal to the center line 406. The length of the line segment 407 connecting the center lines is the interval between the primary strands 303 in the first portion 400, and in FIG. 4b, the center line 405 with respect to the width of one primary strand 303 of the adjacent primary strands 303 and The length of the line segment 408 connecting each center line in the direction orthogonal to the center line 406 with respect to the width of the other primary element wire 303 is the interval between the primary elements 303 in the second portion 401. In the present embodiment, the length of the line segment 407 is longer than the length of the line segment 408. That is, the interval between the primary strands 303 in the first portion 400 is wider than the interval between the primary strands 303 in the second portion 401. As shown in FIG. 2, the second portion 401 is configured to be positioned closer to the surface side of the magnetic body F <b> 1 than the first portion 400. Here, an example of a manufacturing method of the first portion 400 having a large interval between the strands constituting the outermost periphery of the winding W1 and the second portion 401 having a narrow interval between the strands will be described. For example, by suppressing the winding W1 to be sandwiched and applying pressure using a jig or the like until the portion that is not sandwiched is locally deformed, the local area where the pressure is applied becomes narrower between the strands. In the other portions, the spacing between the strands becomes wide. As described above, the winding W1 including the first portion 400 having a wide interval between the strands constituting the outermost periphery and the second portion 401 having a narrow interval between the strands is achieved. This example is an example of a method for manufacturing the first portion 400 having a wide interval between the strands constituting the outermost periphery of the winding W1 and the second portion 401 having a narrow interval between the strands. Various manufacturing methods are applicable without being limited to the above.

  In the present embodiment, the winding W1 has a structure in which the insulating coated conductor 302 is twisted in two stages, but is not limited thereto. Here, with reference to FIG. 5, the winding W1 'having a structure in which the insulation-coated conductors 302 are twisted in three stages will be described. FIG. 5 is a schematic cross-sectional view in which a winding having a structure in which insulation-coated conductors are twisted in three stages is viewed in a direction perpendicular to the extending direction of the winding. As shown in FIG. 4, the winding W <b> 1 ′ is configured by twisting a plurality of stages of insulating coated conductors 302 in which a conductor 301 is covered with an insulating material 300. Specifically, the winding W1 ′ includes a primary strand 303 obtained by twisting a plurality of insulating coated conductors 302, a secondary strand 304 obtained by twisting a plurality of primary strands 303, and a plurality of twisted secondary strands 304. A combined tertiary strand 305 is included. In this example, the winding W1 ′ has a structure in which the insulation coated conductor 302 is twisted in three stages, but may include a quaternary strand (not shown) in which a plurality of tertiary strands 305 are twisted. In addition, a quintic strand (not shown) in which a plurality of quaternary strands are further twisted may be included. When the winding W1 ′ includes the tertiary strand 305, the secondary strand 304 corresponds to the strand constituting the outermost periphery of the winding W1 ′, and when the winding W1 ′ includes the quaternary strand, the tertiary strand When 305 corresponds to a strand constituting the outermost periphery of the winding W1 ′ and includes a fifth strand, the fourth strand corresponds to a strand constituting the outermost periphery of the winding W1 ′. .

  The winding W1 configured in this way has a total cross-sectional area of the winding W1 that is 200 times or more larger than the cross-sectional area of each of the plurality of insulation-coated conductors 302. It is preferable that the number of the insulating coated conductors 302 is configured. In this case, the difference in the spacing between the strands of the first portion 400 and the second portion 401 constituting the outermost periphery of the winding W1 becomes sufficiently large, and further suppresses an increase in AC resistance due to the mirror image effect. And the Q value of the coil C1 can be further greatly improved.

  As described above, in the coil unit Lu1 according to the present embodiment, the winding W1 has the first portion 400 having a large interval between the strands constituting the outermost periphery and the second portion 401 having a small interval between the strands. The second portion 401 is located closer to the surface side of the magnetic body F1 than the first portion 400. Therefore, an increase in AC resistance due to the counter electromotive force generated by the mirror image effect of the magnetic body F1 can be most effectively suppressed, and a reduction in the loss of the coil unit Lu1 can be realized. Further, since the coil unit Lu1 according to the present invention can suppress only the AC resistance without reducing the inductance of the coil C1, the Q value of the coil C1 can be greatly improved. As a result, the transmission efficiency can be increased.

(Modification)
Subsequently, the configuration of a coil unit Lu2 according to a modification of the coil unit Lu1 according to the preferred embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a cross-sectional view of a coil unit according to a modification corresponding to the cross-sectional view of the coil unit according to the preferred embodiment of the present invention shown in FIG. FIG. 7 a is a plan view of a winding as seen from the direction of arrow C in FIG. 6 in a coil unit according to a modification. FIG. 7B is a plan view of the winding as seen from the direction of arrow D in FIG. 6 in the coil unit according to the modification. FIG. 7c is a plan view of the winding as seen from the direction of arrow E in FIG. 6 in the coil unit according to the modification. FIG. 7d is a plan view of the winding viewed from the direction of arrow F in FIG. 6 in the coil unit according to the modification. Note that the coil unit Lu2 according to the present modification is applicable to both the power transmission coil unit Ltu and the power receiving coil unit Lru in the non-contact power transmission device S1. In this modification, the above-described preferred embodiment is that the coil unit Lu2 includes the magnetic body F2 and the coil C2 instead of the magnetic body F1 and the coil C1 of the coil unit Lu1 according to the above-described preferred embodiment. This is different from the coil unit Lu1. That is, the coil unit Lu1 according to the above-described preferred embodiment and the coil unit Lu2 according to the present modification are different in coil type. The following description will focus on differences from the above-described preferred embodiment.

  As shown in FIG. 6, the coil unit Lu2 includes a magnetic body F2 and a coil C2. In the present modification, the outer shape of the magnetic body F2 is a substantially rectangular parallelepiped shape, and the first and second main surfaces F2a and F2b facing each other as the outer surfaces thereof are opposed to the first and second main surfaces F2a and F2b facing each other. It has a second side surface (not shown) and opposed first and second end faces F2c, F2d. The first and second side surfaces extend in the long side direction of the first and second main surfaces F2a and F2b so as to connect the first and second main surfaces F2a and F2b. The first and second end faces F2c, F2d extend in the short side direction of the first and second main faces F2a, F2b so as to connect the first and second main faces F2a, F2b. Further, when the coil unit Lu2 is applied to the power transmission coil unit Ltu or the power reception coil unit Lru, the long side direction of the first and second main surfaces F2a and F2b of the magnetic body F2 is between the power transmission coil unit Ltu and the power reception coil unit Lru. It will be arrange | positioned so that it may correspond to the direction orthogonal to an opposing direction. Such a magnetic body F2 is preferably made of a material having a relatively high relative permeability, and examples thereof include ferrite. In this modification, the magnetic body F2 has a substantially rectangular parallelepiped shape, but may have a cylindrical shape.

  The coil C2 is a coil having a spiral solenoid structure, and is formed by winding the winding W2 on the surface of the magnetic body F2. In this modification, the coil C2 has a winding W2 wound on the first and second main surfaces F2a and F2b and on the first and second side surfaces of the magnetic body F2. Specifically, the coil C2 is wound so that the outer surface of the magnetic body F2 is spirally wound around the opposing direction of the first end face F2c and the second end face F2d. That is, the magnetic body F2 functions as the core of the coil C2. With such a configuration, when the winding W2 of the coil C2 is viewed in cross section, a part of the outer peripheral surface of the winding W2 (upper side in the drawing) located on the first main surface F2a of the magnetic body F2 is made of the magnetic body F2. The part (remaining part) of the outer peripheral surface of the winding W2 (the upper side in the drawing) is disposed so as to be close to the first main surface F2a and away from the first main surface F2a of the magnetic body F2. Further, a part of the outer peripheral surface of the winding W2 (lower side in the drawing) located on the second main surface F2b of the magnetic body F2 is close to the second main surface F2b of the magnetic body F2, and the winding W2 (shown in the drawing). A part (remaining part) of the outer peripheral surface on the lower side is disposed so as to be away from the second main surface F2b of the magnetic body F2.

  The winding W2 is the same as the winding W1 according to the preferred embodiment described above, and the first portion 410 having a large interval between the strands constituting the outermost periphery of the winding W2 and the second having a small interval between the strands. Portion 411. In this modification, the strands that form the outermost periphery of the winding W2 correspond to the primary strands 313. In the first portion 410, as shown in FIGS. 7a and 7c, the interval between the primary strands 313 constituting the outermost periphery of the winding W2 is wide. On the other hand, in the second portion 411, as shown in FIGS. 7b and 7d, the interval between the primary strands 313 constituting the outermost periphery of the winding W2 is narrow. Specifically, in FIG. 7a and FIG. 7c, the direction perpendicular to the center line 416 with respect to the width of one primary strand 313 of the adjacent primary strand 313 and the center line 416 with respect to the width of the other primary strand 313. The lengths of the line segments 417 connecting the respective center lines are the intervals between the primary strands 313 in the first portion 410. In FIGS. 7b and 7d, one of the primary strands 313 adjacent to each other. The length of the line segment 418 connecting the center lines in the direction orthogonal to the center line 416 with respect to the width and the center line 416 with respect to the width of the other primary strand 313 is between the primary strands 313 in the second portion 411. It becomes an interval. In this modification, the length of the line segment 417 is longer than the length of the line segment 418. That is, the interval between the primary strands 313 in the first portion 410 is wider than the interval between the primary strands 313 in the second portion 411. And as FIG. 6 shows, the 2nd part 411 is the 1st main surface F2a and 2nd main surface F2b side of the magnetic body F1 rather than the 1st part 410, ie, the surface side of the magnetic body F1 It is comprised so that it may be located in.

  As described above, in the coil unit Lu2 according to the present modification, the winding W2 includes the first portion 410 having a large interval between the strands constituting the outermost periphery and the second portion 411 having a small interval between the strands. The second portion 411 is located closer to the surface side of the magnetic body F2 than the first portion 410. Therefore, an increase in AC resistance due to the counter electromotive force generated by the mirror image effect of the magnetic body F2 can be most effectively suppressed, and the loss of the coil unit Lu2 can be reduced. Moreover, since the coil unit Lu2 according to the present modification can suppress only the AC resistance without reducing the inductance of the coil C2, the Q value of the coil C2 can be greatly improved. As a result, the transmission efficiency can be increased.

  Hereinafter, according to the above-described embodiment, Examples 1 and 2 and Comparative Examples 1 to 4 can suppress an increase in AC resistance when a magnetic body is disposed close to the coil and greatly improve the Q value of the coil. It shows concretely by.

  As Example 1, the coil unit Lu1 according to the preferred embodiment described above was used. As Example 2, the coil unit Lu2 according to the modification of the coil unit Lu1 according to the preferred embodiment described above was used. As a comparative example 1, in order to compare the characteristics with the first example, in the coil unit Lu1 according to the preferred embodiment described above, a coil unit in which the spacing between the strands constituting the outermost periphery of the winding W1 is uniform is used. Using. As a comparative example 2, in order to compare the characteristics with the example 1, the coil unit Lu1 according to the preferred embodiment described above was obtained by removing the magnetic body F1. As a comparative example 3, in order to compare the characteristics with the example 2, the coil unit Lu2 according to the above-described modified example uses a coil unit in which the spacing between the strands constituting the outermost periphery of the winding W2 is uniform. . As Comparative Example 4, in order to compare the characteristics with Example 2, a coil unit in which the magnetic body F2 was removed from the coil unit Lu2 according to the modification was used.

  First, the configuration of the winding W10 in the coil unit according to Comparative Example 1 will be described with reference to FIG. FIG. 8a is a plan view of the winding of the coil unit according to Comparative Example 1, corresponding to the plan view of the winding as viewed from the direction of arrow A in FIG. FIG. 8b is a plan view of the winding of the coil unit according to the comparative example 1, corresponding to the plan view of the winding seen from the direction of arrow B in FIG. As shown in FIGS. 8a and 8b, the winding W10 in the coil unit according to Comparative Example 1 has a uniform spacing between the strands constituting the outermost periphery of the winding W10. In FIG. 8a, a line connecting the center lines in a direction orthogonal to the center line 705 for the width of one primary strand 703 and the center line 706 for the width of the other primary strand 703 of adjacent primary strands 703. The length of the minute 707 and the center line 705 with respect to the width of one primary strand 703 and the center line 706 with respect to the width of the other primary strand 703 in FIG. The lengths of the line segments 708 connecting the lines are substantially equal. That is, the coil unit according to Comparative Example 1 is configured such that in the coil unit Lu1 according to the preferred embodiment described above, the spacing between the strands constituting the outermost periphery of the winding W1 is made uniform.

  Here, the windings of Examples 1 and 2 and Comparative Examples 1 to 4 were formed by twisting 84 insulation-coated conductors made of copper and having a conductor having a diameter of 0.05 mm covered with urethane resin to form a primary strand. 14 primary strands were twisted together to form secondary strands. Moreover, the 1st part in the coil | winding of Example 1, 2 was 4 mm, the 2nd part was 2 mm, and all the space | intervals between the strands which comprise the outermost periphery of the coil | winding of Comparative Examples 1 and 3 were 3 mm. . Furthermore, the magnetic material in Example 1 and Comparative Example 1 used ferrite (relative magnetic permeability of about 3000) having a length of 200 mm, a width of 200 mm, and a thickness of 6 mm, and the number of winding turns (the number of turns) was 11 turns. Still further, the magnetic material in Example 2 and Comparative Example 3 uses ferrite having a length of 270 mm, a width of 100 mm, and a thickness of 6 mm (relative permeability of about 3000), and the number of winding turns (the number of turns) is 22 turns. did.

  Subsequently, in Examples 1 and 2 and Comparative Examples 1 to 4, the inductance L and the equivalent series resistance value Rs of the coil unit were measured using an impedance analyzer. Further, the transmission frequency of non-contact power transmission was set to 85 kHz, and the Q value was obtained from the measured inductance L and equivalent series resistance value Rs.

  The measurement results of the inductance L in Example 1 and Comparative Examples 1 and 2 are shown in FIG. Moreover, the measurement result of the equivalent series resistance value Rs in Example 1 and Comparative Examples 1 and 2 is shown in FIG. Furthermore, the measurement result of the Q value in Example 1 and Comparative Examples 1 and 2 is shown in FIG. As shown in FIGS. 9 to 11, Example 1 has substantially the same value of inductance L as Comparative Example 1, while the value of equivalent series resistance value Rs is remarkably low. The value is extremely high. Further, in Example 1, compared to Comparative Example 2, the value of inductance L is increased by using a magnetic material, while equivalent series resistance value Rs is low, and as a result, Q value is remarkably high. That is, in Example 1, it was confirmed that the increase in the AC resistance of the coil C was suppressed and the Q value of the coil C was greatly improved.

  The measurement results of the inductance L in Example 2 and Comparative Examples 3 and 4 are shown in FIG. Moreover, the measurement result of the equivalent series resistance value Rs in Example 2 and Comparative Examples 3 and 4 is shown in FIG. Furthermore, the measurement result of the Q value in Example 2 and Comparative Examples 3 and 4 is shown in FIG. As shown in FIGS. 12 to 14, the value of inductance L in Example 2 is substantially equal to that of Comparative Example 3, while the value of equivalent series resistance value Rs is significantly lower. The value is extremely high. Further, in Example 2, the value of the inductance L is increased by using a magnetic material, while the equivalent series resistance value Rs is low, and as a result, the Q value is remarkably high compared to Comparative Example 4. That is, in Example 2, it was confirmed that the increase in the AC resistance of the coil C was suppressed and the Q value of the coil C was greatly improved.

  That is, from the present embodiment and the comparative example, the first portion having a wide interval between the strands constituting the outermost periphery of the winding and the second portion having a narrow interval between the strands, the second portion is The configurations of Example 1 and Example 2 that are located closer to the surface of the magnetic body than the first part can most effectively suppress the increase in AC resistance, and the loss of the coil unit can be reduced. It was confirmed that it could be planned.

  The present invention has been described based on the embodiments. It will be understood by those skilled in the art that the embodiments are illustrative, and that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes are also within the scope of the claims of the present invention. By the way. Accordingly, the description and drawings herein are to be regarded as illustrative rather than restrictive.

  The coil unit according to the present invention can be widely used for a coil unit in a non-contact power transmission system to a vehicle such as an electric vehicle (BEV) or a plug-in hybrid electric vehicle (PHEV: Plug-in Hybrid Electric Vehicle). Is possible.

S1 ... Non-contact power transmission device, Ut ... Power transmission device, PW ... Power source, INV ... Inverter, Rtu ... Power transmission side resonance unit, Ltu ... Power transmission side coil unit, Ctu ... Power transmission side resonance capacitor unit, Ur ... Power reception device, DB ... Rectifier circuit, R ... load, Rru ... power receiving side resonance unit, Lru ... power receiving side coil unit, Cru ... power receiving side resonance capacitor unit, Lu1, Lu2 ... coil unit, C1, C2 ... coil, F1, F2 ... magnetic material, F1a , F2a ... first main surface of the magnetic material, F1b, F2b ... second main surface of the magnetic material, F1c, F2c ... first end surface of the magnetic material, F1d, F2d ... second end surface of the magnetic material, W1 , W1 ', W2, W10 ... winding, 300 ... insulation coating, 301 ... conductor, 302 ... insulation coating conductor, 303, 313, 703 ... primary strand, 304 ... secondary strand, 305 ... tertiary strand , 407, 408, 417, 418, 707, 708 ... the spacing between the strands, 400, 410 ... the first portion where the spacing between the strands is wide, 401, 411 ... the second portion where the spacing between the strands is narrow , 405, 406, 415, 416, 705, 706 ... center line.

Claims (2)

A rod-shaped or plate-shaped magnetic body, and a winding wound on the surface of the magnetic body,
The winding includes a primary strand obtained by twisting a plurality of insulation-coated conductors and a secondary strand obtained by twisting a plurality of the primary strands, and constitutes the outermost periphery of the winding. Having a first portion with a wide spacing between the strands and a second portion with a narrow spacing between the strands;
The coil unit, wherein the second part is located closer to the surface of the magnetic body than the first part. 2. The coil unit according to claim 1, wherein the size of the total area of the cross-section of the winding is 200 times or more with respect to the size of the cross-sectional area per one of the plurality of insulation-coated conductors. .

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