JP2013208012A - Antenna coil unit and magnetic field resonance power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a technique of magnetic field resonance wireless power supply having high transmission efficiency, and a large tolerance at a position where a power supply circuit faces a power receiving circuit.SOLUTION: An antenna coil unit 8 provided in at least one of a power supply circuit and a power receiving circuit includes a plurality of antenna coils 4 constituted by winding a conductor wire 40 around a reference axis X1. The plurality of antenna coils 4 are arranged side by side in a direction for forming magnetic flux of the same phase so that the reference axes X1 adjoin in parallel with each other.

Description

  The present invention relates to an antenna coil unit used for magnetic field resonance type wireless power feeding and a magnetic field resonance type power feeding system using the antenna coil unit.

  Mobile devices, personal information terminals (PDAs), electric assist bicycles, electric vehicles, hybrid vehicles, and other electric devices and electric devices that can be moved without being installed in one place can operate without being supplied with power from the outside. As described above, the battery has a power storage device such as a battery. In recent years, development of a technique for charging a power storage device mounted on such a device or apparatus has been advanced. In many cases, this charging is performed by, for example, connecting a charging port provided in a device or apparatus and a power supply apparatus with a cable or the like.

  However, in recent years, a technique for supplying power wirelessly without using such a cable, that is, contactless, has been attracting attention. One technique for supplying electric power in a non-contact manner uses magnetic resonance. Magnetic field resonance is a resonance between a pair of resonance circuits having a common natural frequency (resonance frequency), for example, a resonance circuit on the power supply equipment side and a resonance circuit on the equipment or device side via a magnetic field. This is a technology for transmitting power through the network. This resonance circuit is usually composed of an LC resonator, and L (inductance) is realized by an antenna coil (resonance coil) serving as an antenna. In order to obtain high transmission efficiency in power transmission using magnetic field resonance, it is necessary that the resonance coil provided in the resonance circuit on the power supply side and the resonance coil provided in the resonance circuit on the power reception side face each other with relatively high accuracy. is there. Here, for example, if the coil unit provided in the resonance circuit on the power supply side or the power reception side has a plurality of resonance coils, the tolerance of the facing accuracy between the resonance coil on the power supply side and the resonance coil on the power reception side is increased. It is possible.

  Japanese Patent Laid-Open No. 2009-106136 (Patent Document 1) discloses a coil unit provided in a resonance circuit on a power feeding side and a power receiving side when power is supplied to a vehicle from a power source outside the vehicle by using magnetic field resonance. A configuration in which at least one has a plurality of resonance coils is disclosed (Patent Document 1: FIGS. 17 to 18 and the like). However, the coil unit of Patent Document 1 is provided with a plurality of resonance coils in order to suppress the strength of the magnetic field other than the space for coupling the resonance circuit on the power supply side and the resonance circuit on the power reception side. In this coil unit, a plurality of resonance coils are arranged such that a magnetic field generated in one resonance coil and a magnetic field generated in at least one other resonance coil are in opposite phases to each other. For example, in the distance where the distance between two resonance coils is negligible, the distance from both resonance coils is almost equivalent, and the magnetic flux is canceled and the strength of the magnetic field can be reduced to almost zero. be able to. However, even between the two resonance coils, there is a position where the distances from both resonance coils are equivalent (Patent Document 1: paragraphs 70, 90 to 93, FIGS. 11 to 12, etc.). For this reason, the magnetic flux is canceled at the exact center between the two resonance coils, in other words, at the center of the coil unit. In other words, depending on the position of the resonance coil on the power supply side and the resonance coil on the power reception side, a place (dead zone) where the magnetic field becomes extremely weak may be generated. Therefore, in the configuration of Patent Document 1, it cannot be said that the tolerance of the facing accuracy of the facing resonance coils is necessarily increased.

JP 2011-23496 A

  In view of the above background, in magnetic field resonance type wireless power feeding, there is a demand for a technology that has a large tolerance between positions where the power feeding circuit and the power receiving circuit face each other and has high transmission efficiency.

  In view of the above problems, an antenna coil unit provided in at least one of the power feeding circuit and the power receiving circuit to perform wireless power feeding by a magnetic field resonance method in which a resonance circuit provided in the power feeding circuit and the power receiving circuit is resonated via a magnetic field. Is presented as follows. That is, the characteristic configuration of the antenna coil unit according to the present invention includes a plurality of antenna coils configured by winding a conductor wire around a reference axis, and the plurality of antenna coils are oriented in such a manner that magnetic fluxes having the same phase are formed. Thus, the plurality of antenna coils are arranged side by side so that the reference axes are adjacent to each other in parallel.

  According to this characteristic configuration, at least one of the power feeding circuit and the power receiving circuit is provided with the antenna coil unit configured to include the plurality of antenna coils. Therefore, the relative positions where the antenna coil of the power feeding circuit and the antenna coil of the power receiving circuit overlap are distributed over a wide range when viewed in the direction along the direction in which the power feeding circuit and the power receiving circuit face each other. That is, the tolerance of the position where the power feeding circuit and the power receiving circuit face each other is increased. Further, according to this characteristic configuration, the plurality of antenna coils arranged side by side are adjacent to each other in a direction in which magnetic fluxes having the same phase are formed and the reference axes around which the conductor wire circulates are parallel to each other. Therefore, the magnetic flux generated from both antenna coils is not canceled even on the side where the antenna coils are adjacent to each other. For this reason, for example, the antenna coil unit is configured by two antenna coils (for example, “coil A” and “coil B”), and the coil A from the position on the side away from the coil B (for example, “position A”) And a magnetic field that mediates magnetic resonance in a relatively wide range from a position between the coil B and the coil B (for example, “position AB”) to a position on the side of the coil B away from the coil A (for example, “position B”). Can appear. That is, according to this characteristic configuration, a wide resonance range can be provided without causing a dead zone. As described above, according to this feature configuration, it is possible to realize magnetic field resonance type wireless power feeding having a large tolerance between positions where the power feeding circuit and the power receiving circuit face each other and having high transmission efficiency.

  Here, it is preferable that the antenna coil unit according to the present invention is configured by connecting the plurality of antenna coils in series. In the magnetic field resonance type wireless power feeding, it is preferable to increase the resonance sharpness Q of the resonance circuit. For example, when the resonance circuit is configured by an LC resonator, “Q” increases as “L” (inductance) increases. Therefore, it is preferable that the connection form of the plurality of antenna coils is such that the inductance is further increased. When the antenna coils are connected in parallel, the total inductance is the reciprocal of the sum of the reciprocals of the respective inductances. For example, when two antenna coils having the same inductance are connected in parallel, the total inductance is ½. When the antenna coils are connected in series, the total inductance is the sum of the inductances. For example, when two antenna coils having the same inductance are connected in parallel, the total inductance is doubled.

  When the antenna coils are adjacent to each other, they may affect each other and reduce the inductance of each antenna coil. This influence tends to become stronger as the distance between the plurality of antenna coils is shorter. Therefore, as one aspect, the antenna coil units according to the present invention set the separation distance based on the amount of decrease in inductance of each antenna coil due to the influence of the other adjacent antenna coil, and the separation distance is equal to each other. It is preferable that the plurality of antenna coils be arranged apart from each other.

  By the way, by providing the antenna coil unit as described above, it is possible to construct the following magnetic field resonance type power feeding system. As one aspect, in the magnetic field resonance type power feeding system according to the present invention, the power feeding circuit is configured to include the antenna coil unit, and the power receiving circuit is configured to include one antenna coil. Here, the effective area, which is an area surrounded by the outer periphery of the antenna coil viewed in the direction along the reference axis, is the sum of the effective areas of the plurality of antenna coils included in the antenna coil unit of the feeder circuit. It is preferable that the width is set wider than the effective area of the antenna coil of the power receiving circuit. According to this configuration, the relative position where the antenna coil unit of the power feeding circuit and the antenna coil of the power receiving circuit overlap is distributed over a wide range as viewed in a direction along the direction in which the power feeding circuit and the power receiving circuit face each other. Become. In other words, according to this configuration, the tolerance of the position where the power feeding circuit and the power receiving circuit face each other is increased, and magnetic resonance wireless power feeding having high transmission efficiency can be realized.

  Here, in the magnetic field resonance type power feeding system according to the present invention, the effective area of each of the plurality of antenna coils constituting the antenna coil unit of the power feeding circuit is equal to that of the one antenna coil of the power receiving circuit. It is preferable to be equal to the area. According to this configuration, for example, a case that accommodates each antenna coil can be made common to all antenna coils, and a magnetic field resonance power feeding system can be constructed at a low cost. Further, since the antenna coil unit provided in the power feeding circuit has at least two antenna coils, the antenna coil unit has an effective area at least twice that of the power receiving circuit. Therefore, it is possible to secure a relative position over a wide range where the antenna coil unit of the power feeding circuit and the antenna coil of the power receiving circuit completely overlap when viewed in a direction along the direction in which the power feeding circuit and the power receiving circuit face each other. it can.

Block diagram schematically showing the configuration of the wireless power supply system Circuit block diagram schematically showing the configuration of the wireless power supply system Resonant circuit equivalent circuit diagram Diagram showing the magnetic field generated by the current flowing through the antenna coil The figure explaining the concept of the opposing error of the antenna coil in magnetic resonance Diagram showing the magnetic field generated by the current flowing through the antenna coil The figure which shows the magnetic field produced by the electric current which flows through an auxiliary coil part The figure which shows the relationship between the magnetic field which mediates magnetic resonance, and an antenna coil A perspective view showing an example of an antenna coil A perspective view showing an example of an antenna coil Partial enlarged view of antenna coil Diagram showing direction of current flowing through antenna coil A perspective view showing an example of an antenna coil unit Schematic circuit block diagram of a system to which an antenna coil unit is applied The figure which shows the opposing error of an antenna coil unit and an antenna coil The figure which shows the opposing error of an antenna coil and an antenna coil Graph showing the relationship between counter error ratio and transmission efficiency Graph showing the relationship between counter error and resonance frequency fluctuation The figure which shows an example of the relationship between the electric power feeding side resonance coil and a receiving side resonance coil The figure which shows an example of the relationship between the electric power feeding side resonance coil and a receiving side resonance coil

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking as an example a magnetic resonance power feeding system that wirelessly feeds a vehicle. As shown in FIG. 1, the magnetic field resonance power supply system 1 includes a power supply system 2 installed in a power supply facility and a power reception system 3 mounted on the vehicle 9 side. In the present embodiment, for example, the power feeding system 2 is installed near the ground G if it is an outdoor facility, or near the floor surface if it is an indoor facility.

  As shown in FIGS. 1 and 2, the power feeding system 2 includes an AC power source 21, a driver circuit 22, and a power feeding side resonance circuit 25. The power supply side resonance circuit 25 includes a power supply side resonance coil 24. The power receiving system 3 includes a power receiving side resonance circuit 35, a rectifier circuit 32, and a power storage device 31. The power reception side resonance circuit 35 includes a power reception side resonance coil 34. The power supply side resonance circuit 25 and the power reception side resonance circuit 35 are resonance circuits having the same natural frequency (resonance frequency), and are collectively referred to as a resonance circuit 5. The power supply side resonance coil 24 and the power reception side resonance coil 34 are collectively referred to as a resonance coil or an antenna coil 4.

  The AC power supply 21 of the power supply system 2 is, for example, a power supply (system power supply) supplied from a commercial distribution network owned by an electric power company, and the frequency thereof is, for example, 50 Hz or 60 Hz. The driver circuit 22 is a circuit that converts the frequency of the system power supply of 50 Hz or 60 Hz into the resonance frequency of the power supply side resonance circuit 25 (resonance circuit 5), and is configured by a high frequency power supply circuit. The power storage device 31 of the power receiving system 3 is a DC power source that can be charged and discharged, and for example, a secondary battery or a capacitor such as lithium ion or nickel metal hydride is used. The power received by the power reception side resonance circuit 35 is AC power having the resonance frequency of the power reception side resonance circuit 35. The rectifier circuit 32 is a circuit that rectifies AC power having this resonance frequency into DC power.

  The driver circuit 22 and the power supply side resonance circuit 25 together or the entire power supply system 2 corresponds to a power supply circuit in a broad sense. The power supply side resonance circuit 25 corresponds to a power supply circuit in a narrow sense. Similarly, the power receiving side resonance circuit 35 and the rectifier circuit together or the entire power receiving system 3 corresponds to a power receiving circuit in a broad sense. The power receiving side resonance circuit 35 corresponds to a power receiving circuit in a narrow sense.

  The vehicle 9 is, for example, an electric vehicle driven by a rotating electrical machine 91 or a hybrid vehicle driven by an internal combustion engine (not shown) and the rotating electrical machine 91. The rotating electrical machine 91 is connected to the power storage device 31 via a rotating electrical machine drive device such as an inverter 92, for example. In the present embodiment, the rotating electrical machine 91 is, for example, a three-phase AC rotating electrical machine, and the rotating electrical machine driving device is configured with an inverter 92 that converts power between direct current and alternating current as a core. The rotating electrical machine 91 can function as an electric motor and a generator. When the rotating electrical machine 91 functions as an electric motor, it receives power supplied from the power storage device 31 via the inverter 92 and generates a driving force (power running operation). On the other hand, when the rotating electrical machine 91 functions as a generator, AC power generated by braking of the vehicle 9 or driving force of an internal combustion engine or the like is converted into DC by the inverter 92 and regenerated to the power storage device 31 ( Regenerative operation).

  As shown in FIG. 2, the magnetic field resonance power supply system 1 is a system that resonates a pair of resonance circuits 5 (25, 35) via a magnetic field and supplies power via the magnetic field. As a “resonance” technique using “magnetism”, magnetic resonance imaging (MRI) often used in the medical field is known. However, while MRI uses the physical phenomenon of “magnetic spin resonance”, the “magnetic resonance power supply system” in the present invention does not use such a physical event. In the “magnetic resonance power feeding system” in the present invention, as described above, the two resonance circuits 5 are resonated via the “magnetic field”. Accordingly, here, the transmission method of the magnetic field resonance power feeding system 1 that transmits power using resonance in a magnetic field, including clearly distinguishing from so-called MRI, is referred to as a “magnetic field resonance method”. This transmission method is different from the so-called “electromagnetic induction method”, but this point will be described later.

  As described above, the power supply side resonance circuit 25 and the power reception side resonance circuit 35 have the same natural frequency (resonance frequency). In the present embodiment, the power supply side resonance circuit 25 and the power reception side resonance circuit 35 are LC resonators having the same configuration. Therefore, in the following description, when it is not necessary to distinguish between the two, it will be described as “resonance circuit 5”. As shown in the equivalent circuit of FIG. 3, the resonance circuit 5 includes an antenna coil 4 having an inductance component “L” and a capacitor 6 having a capacitance component “C”. In the present embodiment, as shown in FIG. 2, the capacitance component “C” is a combination of the capacitance components (Cs, Cs, Cp) of the three capacitors.

  The power supply side resonance circuit 25 and the power reception side resonance circuit 35 are circuits having the same resonance frequency. For example, when one of two tuning forks arranged apart from each other is vibrated in the air, the other tuning fork also vibrates in resonance with vibration propagated through the air. 25 and the power receiving resonance circuit 35 also resonate. More specifically, the power receiving side resonance circuit 35 resonates in resonance with the electromagnetic vibration propagated to the power receiving side resonance circuit 35 via the magnetic field generated by the resonance (electromagnetic vibration) of the power supply side resonance circuit 25 (electromagnetic). To vibrate).

  By the way, an “electromagnetic induction method” is known as a non-contact power transmission method. In particular, the circuit configuration of an electromagnetic induction method using magnetic field coupling is very similar to that shown in FIG. However, the “electromagnetic induction method” uses an electromotive force generated by a change in the strength of magnetic flux passing between the coils, and the coupling between the coils (magnetic field coupling) is generally dominant. In the electromagnetic induction system, the coupling strength of two circuits is often expressed by the self-inductance (L1, L2) and mutual inductance M of each of the two coils as shown in the following formula (1). When all the magnetic fluxes generated by the two coils are linked, the coupling strength is “1”.

  On the other hand, in the “magnetic resonance method”, both “magnetic field coupling” due to the inductance L between the two resonance circuits 5 and “electric field coupling” due to the capacitance C affect the transmission efficiency. In other words, the performance of the resonance circuit 5 as an LC resonator greatly affects the transmission efficiency. In the “magnetic resonance type” wireless power supply, the transmission efficiency of the power supply is determined by the “coupling coefficient” (hereinafter simply referred to as “resonance circuit 5 of the resonance circuit 5”) of the power supply side resonance circuit 25 and the power reception side resonance circuit 35 constituting the magnetic field resonance type power supply system 1. And may be referred to as “coupling coefficient”), and is governed by a parameter of “no load Q” (resonance sharpness at no load) of the resonance circuit 5.

  Here, since the coupling coefficient can use the coupling strength of the electromagnetic induction method, a detailed description is omitted. The no-load Q is represented by the following equation (2), where R is the resistance component of the circuit in the equivalent circuit shown in FIG. Here, it is assumed that the circuit constants of the two resonance circuits 5 to be resonated are the same (L = L1 = L2, C = C1 = C2, R = R1 = R2).

  The transmission efficiency of the magnetic field resonance method is governed by a “kQ product” that is a product of the coupling coefficient k of the resonance circuit 5 and the no-load Q of the resonance circuit 5. Therefore, in the magnetic field resonance method, it is preferable to increase the transmission efficiency by increasing (increasing) the no-load Q. As one aspect, it is preferable to set the no-load Q to “100” or more.

  In more detail, the efficiency of the magnetic field resonance power feeding system 1 includes the efficiency of the driver circuit 22 of the power feeding system 2, the efficiency of the spatial transmission unit configured by the power feeding side resonance circuit 25 and the power receiving side resonance circuit 35 (the above “ kQ product ") and the product of the efficiency of the rectifier circuit 32. The driver circuit 22 and the rectifier circuit 32 are both circuits that involve frequency conversion, and the efficiency is governed by the frequency characteristics of the semiconductor elements that constitute these circuits.

  The principle of the magnetic field resonance type power feeding system 1 has been described above. However, the magnetic field resonance type power feeding system 1 has a large tolerance between positions where the power feeding side resonance circuit 25 and the power receiving side resonance circuit 35 face each other, and has high transmission efficiency. It is preferable. First, the “opposing position” will be described.

  FIG. 4 schematically shows the antenna coil 4 configured by turning the conductor wire 40 around the reference axis (first reference axis X1). The antenna coil 4 shown in FIG. 4 is appropriately referred to as a “main coil portion 41” when it is necessary to distinguish from an auxiliary coil portion 42 described later. In this antenna coil 4 (main coil portion 41), a magnetic flux φ1 is generated by a current flowing through the conductor wire 40. The antenna coil 4 is provided in the power supply side resonance circuit 25 and the power reception side resonance circuit 35 as the power supply side resonance coil 24 and the power reception side resonance coil 34, respectively. As shown in FIG. 5, when the power supply side resonance coil 24 and the power reception side resonance coil 34 are opposed to each other, the power reception side resonance circuit 35 resonates with the power supply side resonance circuit 25 via a magnetic field. As shown in FIG. 5, when the first reference axis X1 of the power supply side resonance coil 24 and the first reference axis X1 of the power reception side resonance coil 34 coincide with each other, there is no positional deviation, and the facing error d is “ 0 ".

  By the way, it is not necessary to spread the magnetic field in the direction along the first reference axis X1 on the side opposite to the side where the power supply side resonance coil 24 and the power reception side resonance coil 34 face each other, that is, on the back side. On the other hand, as shown in FIG. 1, when the magnetic field resonance power feeding system 1 is applied to the vehicle 9, the magnetic flux φ 1 is applied to the vehicle 9, particularly when the magnetic field reaches the back side of the power reception side resonance coil 34. There is a possibility of affecting the iron plate at the bottom and the equipment inside the vehicle 9. Therefore, in the present embodiment, the antenna coil 4 is provided with directivity to suppress leakage of magnetic flux to a space other than the space where the magnetic field that couples the resonance circuit 5 on the power feeding side and the power receiving side is formed. Adopt the configuration.

  Specifically, as shown in FIG. 6, at least one auxiliary coil is arranged along one axial end face (back side axial end face PB) of the main coil section 41 and has a smaller diameter than the main coil section 41. The antenna coil 4 is configured to include the portion 42. The auxiliary coil section 42 is configured by winding a conductor wire 40 around a second reference axis X2 different from the first reference axis X1. The second reference axis X2, which is the rotation axis of the auxiliary coil portion 42, is set in a direction that intersects the magnetic flux φ1 of the main coil portion 41, and preferably in a substantially orthogonal direction. As will be described later with reference to FIG. 12, the auxiliary coil unit 42 has a component (I2) parallel to the circumferential direction of the main coil unit 41 among the components of the current flowing through the auxiliary coil unit 42. It is arranged so that it is in the same direction as the current (I1) flowing through the main coil portion 41 on the side close to 41.

  A magnetic flux φ2 is generated in the auxiliary coil section 42 as shown in FIG. As shown in FIG. 6, on the side where the auxiliary coil portion 42 is provided, the magnetic flux (φ1) of the main coil portion 41 bypasses the auxiliary coil portion 42 and is on one side in the axial direction of the first reference axis X1 (FIG. 6). (The magnetic flux φ4) without spreading to the back side axial end surface PB (to be described later). On the other hand, the magnetic flux spreads in the axial direction of the first reference axis X1 on the other side in the axial direction (the lower side in FIG. 6, the side of the opposing axial end surface PF) where the auxiliary coil part 42 is not provided. (Magnetic flux φ4). That is, as shown in FIG. 6, when the antenna coil 4 is opposed, the spread of the magnetic flux to one side of the first reference axis X1 is suppressed and the spread of the magnetic flux to the other side is not hindered. That is, as shown in FIG. 8, on one side of the first reference axis X1 (on the back side axial end face PB side), the influence of the magnetic field on the iron plate at the bottom of the vehicle 9 and the equipment in the vehicle 9 is suppressed. On the other side (opposite side axial end surface PF side), magnetic flux for magnetic field resonance can be applied to the corresponding resonance circuit 5.

  9 and 10 show an example of a specific configuration of such an antenna coil 4. FIG. 9 is a perspective view of the antenna coil 4 as viewed from the opposite axial end surface PF, which is the axial end surface on the opposite side during power feeding. FIG. 10 is a perspective view of the antenna coil 4 as seen from the back side axial end face PB. In this example, the antenna coil 4 includes 16 auxiliary coil portions 42. The magnetic field spreads in all radial directions of the main coil portion 41. Therefore, in order to guide the magnetic flux using the auxiliary coil portion 42 and suppress the leakage magnetic flux, it is preferable that the plurality of auxiliary coil portions 42 are arranged in the circumferential direction of the main coil portion 41 as described above.

  In addition, it is preferable that the auxiliary coil portions 42 be arranged at equal intervals in the circumferential direction of the main coil portion 41 so that a blank area in which suppression of leakage magnetic flux is weakened in the circumferential direction of the main coil portion 41 is not generated as much as possible. is there. When the main coil portion 41 is annular when viewed in the direction along the first reference axis X1, it can be easily realized by setting the second reference axis X2 in the circumferential direction of the main coil portion 41 at the same angular interval. It is. Further, when the main coil portion 41 is formed in a rectangular ring shape when viewed in the direction along the first reference axis X1, for example, as shown in FIG. 9 and FIG. Is preferred. Also in this case, it can be said that the main coil portions 41 are arranged at equal intervals in the circumferential direction. Similarly, even when the main coil portion 41 is formed in an elliptical shape, a track shape, or the like, it is preferable that the auxiliary coil portion 42 be arranged substantially evenly in the circumferential direction of the main coil portion 41.

  The directivity and efficiency of the antenna coil 4 vary depending on the number of turns of the main coil portion 41 and the auxiliary coil portion 42 and the inductance. The inductances of the main coil portion 41 and the auxiliary coil portion 42 are appropriately set according to the specifications of the magnetic field resonance type power feeding system 1. For example, since the magnetic field that mediates the resonance of the two resonance circuits 5 is a magnetic field that mainly depends on the main coil portion 41, the sum of all the inductances of the auxiliary coil portion 42 is larger than the inductance of the main coil portion 41. Configured to be smaller.

  The main coil portion 41 of the antenna coil 4 shown in FIGS. 9 and 10 is formed in a spiral shape along a reference plane PR orthogonal to the first reference axis X1. In order to easily define the reference plane PR, the substrate material 70 (core member 7) is used when the main coil portion 41 is formed. The substrate material 70 is made of, for example, polycarbonate or polypropylene. In the magnetic field resonance type power feeding system 1, the LC resonator (resonance circuit 5) as a pair is resonated via a magnetic field. The antenna coil 4 is a resonance coil corresponding to the inductor (L) in this LC resonator. If the capacitor (C) of the LC resonator is configured using the core member 7, the LC resonator can be constructed by the assembly of the antenna coil 4. In configuring a capacitor having high frequency characteristics, it is preferable that the value of the dielectric loss tangent of the core member 7 is small (for example, less than 0.003 in the target frequency band). Polycarbonate and polypropylene are materials having a dielectric loss tangent of approximately 0.002 or less and a low dielectric loss tangent value, and are suitable as the main material of the core member 7.

  The substrate material 70 is provided with a plurality of shaft core portions 72 in order to define the second reference axis X2. These shaft core portions 72 are connected by a connecting portion 71. The connecting portion 71 is a plane orthogonal to the first reference axis X1, and defines a reference plane PR. Since the auxiliary coil portion 42 is a coil having a smaller diameter than the main coil portion 41, the inductance of one auxiliary coil portion 42 tends to be small. Therefore, the auxiliary coil portion 42 includes a magnetic auxiliary coil core 43 as shown in FIG. 10 in order to ensure necessary inductance. The auxiliary coil core 43 is preferably made of a ferromagnetic material having a high magnetic permeability and a high specific resistance, such as ferrite. In order to effectively guide the magnetic flux generated by the current flowing through the main coil portion 41, the auxiliary coil portion 42 is preferably arranged in the vicinity of the main coil portion 41 in the radial direction of the main coil portion 41. Therefore, as shown in FIGS. 9 and 10, the auxiliary coil portion 42 is disposed so as to have a portion overlapping the main coil portion 41 when viewed in the axial direction of the first reference axis X <b> 1.

  The main coil portion 41 is formed through a main coil portion forming step in which the conductor wire 40 is spirally wound around the first reference axis X1 along the reference plane PR orthogonal to the first reference axis X1. The auxiliary coil portion 42 is formed around the second reference axis X2 through an auxiliary coil portion forming step in which the conductor wire 40 is circulated with a smaller diameter than the radius of the conductor wire 40 in the main coil forming step. The auxiliary coil portion forming step is performed while the conductor wire 40 is turned around the first reference axis X1 in the main coil portion forming step. Note that “while turning” includes the beginning of the main coil portion forming step and the end of the main coil portion forming step.

  By the way, in the main coil part 41 and the auxiliary coil part 42, if the adjacent conductor wires 40 are too close to each other, the interaction between the currents flowing in the adjacent conductor wires 40 due to the magnetic field induced by the current flowing in the antenna coil 4 occurs. The proximity effect is stronger. That is, the proximity effect has the effect of keeping away the current flowing in the same direction. This proximity effect acts in the direction of reducing the no-load Q. In addition, a stray capacitance (parasitic capacitor) may be generated between the adjacent conductor lines 40 to affect the impedance of the antenna coil 4. For this reason, it is preferable that the conductor wire 40 is wound somewhat loosely, rather than densely winding between the wires. For example, it is preferable that the conductor wire 40 is wound with a gap of about 1 to 2 times the wire diameter. When the auxiliary coil portion generation step is performed in the middle of the main coil portion generation step, a gap corresponding to the conductor wire 40 that circulates in the auxiliary coil portion 42 is provided between the conductor wires of the main coil portion 41 as shown in FIG. It is formed. For example, in the auxiliary coil portion 42, when the conductor wire 40 is wound once without any gap, a gap corresponding to almost one conductor wire 40 is between the conductor wires 40 constituting the main coil portion 41. Will be formed.

  FIG. 12 is a view of the antenna coil 4 as viewed along the axial direction of the second reference axis X2. As shown in FIG. 12, the component parallel to the circumferential direction of the main coil portion 41 among the components of the current I2 flowing through the auxiliary coil portion 42 is the current I1 flowing through the main coil portion 41 on the side close to the main coil portion 41. The same direction. Therefore, even if the auxiliary coil portion 42 is provided for the main coil portion 41, the loss of the magnetic field for magnetic field resonance is suppressed, and the transmission efficiency is hardly lowered.

  As described above, the magnetic field resonance type power feeding system 1 preferably has a large tolerance in a position where the power feeding side resonance circuit 25 and the power receiving side resonance circuit 35 face each other and has high transmission efficiency. In the present invention, a magnetic resonance type feeding system 1 having a large allowable range for allowing the facing error d described with reference to FIG. 5 is constructed, and an antenna coil unit (8) applied to such a system is provided. It has a feature in the configuration. As shown in FIGS. 13 and 14, the antenna coil unit 8 includes a plurality of antenna coils 4 each configured by winding a conductor wire 40 around a reference axis (first reference axis X1). Further, the antenna coil unit 8 is arranged in such a direction that the plurality of antenna coils 4 form magnetic fluxes (φ4) having the same phase, and the reference axes (first reference axes X1) are adjacent to each other in a parallel state. A plurality of antenna coils 4 are arranged side by side.

  The plurality of antenna coils 4 are connected in series as shown in FIG. As described above, in the magnetic field resonance type wireless power feeding, it is preferable to increase the resonance sharpness Q of the resonance circuit. When the resonance circuit is composed of an LC resonator, as shown in Expression (2), “Q” increases as “L” (inductance) increases. When the antenna coil 4 is connected in series, the total inductance of the antenna coil unit 8 is the sum of the inductances. For example, when two antenna coils 4 having the same inductance are connected in parallel, the total inductance is doubled. In other words, the inductance of each antenna coil 4 may be ½ of the inductance required for the antenna coil unit 8. Thus, it is preferable that the connection form of the plurality of antenna coils 4 is a series connection in which the inductance is further increased.

  Of course, the antenna coil 4 can be connected in parallel depending on the conditions, such as when an inductance capable of obtaining the necessary “Q” can be secured or when the necessary “Q” can be obtained by the capacitance of the LC resonator. It does not prevent you from being done.

  By the way, if the antenna coils 4 are adjacent to each other, they may affect each other to reduce the inductance of each antenna coil 4. This influence tends to become stronger as the separation distance SD of the plurality of antenna coils 4 is closer. Therefore, the separation distance SD is set so that the amount of decrease in inductance of the adjacent antenna coil 4 is sufficiently small to be negligible compared to the inductance (inherent inductance) when the antenna coil 4 is installed alone. It is preferable that Here, “small enough to be ignored” means, for example, that the amount of decrease in inductance is several percent of the inherent inductance (less than 10%), depending on the specifications required for the magnetic field resonance power feeding system 1. It is prescribed. That is, the antenna coil unit 8 sets the separation distance SD based on the amount of decrease in inductance of each antenna coil 4 due to the influence of the other adjacent antenna coil 4, and is separated from each other by the separation distance SD. The coil 4 is arranged.

  Needless to say, in a case where the mounting property is given priority, the plurality of antenna coils 4 are not separated from each other without being separated by the separation distance SD. In other words, if the specification of the entire system can permit a decrease in “Q” or transmission efficiency due to a decrease in inductance due to the influence of the adjacent antenna coil 4, it prevents the separation distance SD from being arranged at “0”. is not.

  As shown in FIG. 15, such an antenna coil unit 8 is used as the power supply side resonance coil 24 of the power supply side resonance circuit 25, and one antenna coil 4 is used as the power reception side resonance coil 34 of the power reception side resonance circuit 35. It is possible to construct the magnetic field resonance power supply system 1. At this time, the antenna coil unit 8 of the power supply side resonance circuit 25 has an effective area that is an area surrounded by the outer periphery of the antenna coil 4 as viewed in the direction along the reference axis (first reference axis X1) of the antenna coil 4. The total effective area “S2” of the plurality of antenna coils 4 is set to be larger than the effective area “S3” of the antenna coil 4 of the power receiving side resonance circuit 35.

  When set in this way, the feeding-side resonance coil 24 (antenna coil unit 8) is seen in a direction along the direction in which the feeding-side resonance coil 24 (antenna coil unit 8) and the power-receiving-side resonance coil 34 face each other. Therefore, the relative position where the power receiving side resonance coil 34 overlaps is distributed over a wide range. Thereby, the tolerance of the position where the power supply side resonance coil 24 (antenna coil unit 8) and the power reception side resonance coil 34 face each other is increased, and the magnetic field resonance power supply system 1 having high transmission efficiency is realized. As for the reference of the opposing position, the antenna coil unit 8 is an axis passing through the center of the magnetic field as the power supply side resonance coil 24 and parallel to the first reference axis X1. When the antenna coil unit 8 is composed of two antenna coils 4 having the same specifications as shown in FIG. 15, it becomes a reference for a position where the midpoint of both antenna coils 4 is opposed.

  Here, it is preferable that the effective area “S2” of each of the plurality of antenna coils 4 constituting the power supply side resonance coil 24 (antenna coil unit 8) is equal to the effective area “S3” of the power reception side resonance coil 34. For example, a case accommodating each antenna coil 4 can be shared by all the antenna coils 4, and the magnetic field resonance power feeding system 1 can be constructed at a low cost. Further, since the antenna coil unit 8 as the power supply side resonance coil 24 has at least two antenna coils 4, the antenna coil unit 8 has an effective area at least twice that of the power reception side resonance coil 34. Accordingly, the power supply side resonance coil 24 (antenna coil unit 8) and the power reception side resonance coil 34 are viewed in a direction along the direction in which the power supply side resonance coil 24 (antenna coil unit 8) and the power reception side resonance coil 34 face each other. It is possible to secure a relative position where the two completely overlap with each other over a wide range.

  FIG. 17 shows the relationship between the facing error d and the transmission efficiency. FIG. 17 shows an experimental result in which the transmission efficiency is measured by combining the power supply side resonance coil 24 and the power reception side resonance coil 34 in three different patterns. In this experiment, with respect to the power supply side resonance coil 24, the power reception side resonance coil 34 is moved along a straight line (measurement reference line) passing through a reference point that is the center position of the magnetic field of the power supply side resonance coil 24. The transmission efficiency is measured. The “antenna length AL” to be described later is the length of the power supply side resonance coil 24 in the direction along the measurement reference straight line (the length between the outermost conductor lines 40).

In FIG. 17, the characteristic “T1” is a characteristic when the power supply side resonance coil 24 (antenna coil unit 8) and the power reception side resonance coil 34 are combined as shown in FIG. As shown in FIG. 16, the characteristic “T2” is a characteristic when a power feeding side resonance coil 24 and a power receiving side resonance coil 34 configured by a single antenna coil 4 having the same specifications are combined. The characteristic “T3” is the same as that of FIG. 15 in terms of the outer shape, but the antenna coil 4 and the antenna coil unit 8 that are arranged adjacent to each other so that the magnetic flux is not in phase but in opposite phase, and the power reception side resonance. This is a characteristic when the coil 34 is combined. Note that the horizontal axis of the graph shown in FIG. 17 represents the counter error d by the “counter error ratio” shown below in order to align the comparison conditions.
Opposing error ratio = (opposing error d / antenna length AL) × 100 [%]

  As shown in FIG. 17, the antenna coil unit 8 (characteristic “T1”) configured by including a plurality of antenna coils 4 has a wider counter error than the single antenna coil 4 (characteristic “T2”). Good transmission efficiency can be exhibited within the ratio range. The value of the transmission efficiency of the single antenna coil 4 exceeds the antenna coil unit 8 by about 4 to 5% at maximum, but the transmission efficiency of the antenna coil unit 8 is also about 90% or more. It shows a sufficiently high efficiency for practical use. On the other hand, in the antenna coil unit 8 in which the antenna coils 4 are adjacently arranged so that the magnetic fluxes of the antenna coils 4 are in opposite phases, the transmission efficiency is substantially “0” at the center position where the opposing error ratio is near “0”. For example, the transmission efficiency is greatly reduced in the vicinity of the center position, and a so-called dead zone is generated. Therefore, as described above, when the antenna coil unit 8 is configured, it is preferable that the plurality of antenna coils 4 be arranged adjacent to each other in a direction in which magnetic fluxes having the same phase are formed.

  By the way, in the magnetic field resonance type power feeding system 1, the accuracy of the resonance frequency of the resonance circuit 5 is important, but this resonance frequency fluctuates due to the influence of the facing error d. FIG. 18 shows the relationship between the facing error d and the variation rate of the resonance frequency. In FIG. 18, the characteristic “T4” is a characteristic when the power supply side resonance coil 24 (antenna coil unit 8) and the power reception side resonance coil 34 are combined as shown in FIG. As shown in FIG. 16, the characteristic “T5” is a characteristic when a power feeding side resonance coil 24 and a power receiving side resonance coil 34 configured by a single antenna coil 4 having the same specifications are combined.

  When the facing error d is near “0”, the single antenna coil 4 has a frequency closer to the resonance frequency than the antenna coil unit 8. This appears as a difference in transmission efficiency as described above with reference to FIG. However, considering the variation rate, the single antenna coil 4 is configured to have a plurality of antenna coils 4 whereas the frequency variation of about 9% is generated according to the facing error d. In the antenna coil unit 8, the frequency fluctuation corresponding to the facing error d remains at about 5%. In other words, the resistance of the frequency fluctuation to the facing error d is stronger in the antenna coil unit 8 than in the single antenna coil 4.

  In order to obtain the magnetic field resonance type power feeding system 1 having high transmission efficiency, it is preferable that the resonance frequency fluctuates little. In addition, since the magnetic field resonance type power feeding system 1 is a system using non-contact power transmission technology, it may be subject to legal regulations such as the Radio Law in Japan. In the case of the magnetic field resonance power supply system 1, the frequency band subject to legal regulations corresponds to the resonance frequency of the resonance circuit 5. If the variation in the resonance frequency of the resonance circuit 5 is small, it becomes easy to configure the resonance circuit 5 that satisfies the legal regulations, which contributes to the cost reduction of the entire system.

  When the antenna coil unit 8 is provided in the power supply side resonance circuit 25, the pair of power reception side resonance circuits 35 includes the antenna coil unit 8 having a single antenna coil 4 or a plurality of antenna coils 4. Hereinafter, the resonance coil (antenna coil 4 or antenna coil unit 8) provided in the power receiving side resonance circuit 35 will be described. Here, it is assumed that the antenna coil unit 8 provided in the power supply side resonance circuit 25 includes the two antenna coils 4 as described above. The power supply side resonance circuit 25 and the power reception side resonance circuit 35 may be resonance circuits having the same resonance frequency. For example, in the case of an LC resonator, the resonance frequency is defined by “L” and “C”. . For this reason, for example, if the values of “L” in the two resonance circuits 5 are different, it is possible to adjust with the value of “C”. However, here, the inductance “L” on the power feeding side and the power receiving side. The case where "" is the same value is illustrated.

The power receiving side resonance circuit 35 can be configured to include, for example, three patterns of resonance coils. Here, the expression “same” is used in order to facilitate comparison, but this does not indicate a strict concept, but naturally includes the concept of “same level”.
(1) One antenna coil 4 having the same effective area as one antenna coil 4 of the antenna coil unit 8 of the power supply side resonance circuit 25 and having the same inductance as the whole antenna coil unit 8 (see FIG. 15). However, the effective area is an area surrounded by the outer periphery of the antenna coil 4 as viewed in the direction along the reference axis (first reference axis X1).
(2) The antenna coil unit 8 (see FIG. 19) having the same configuration (effective area and inductance) as the power supply side resonance circuit 25.
(3) One antenna coil 4 having the same effective area as that of the feeding-side resonance circuit 25 and having the same inductance as that of the entire antenna coil unit 8 (see FIG. 20).

  The configuration (1) can reduce the size of the resonance coil (antenna coil 4) provided in the power reception side resonance circuit 35. Therefore, for example, space saving can be realized when the power receiving side resonance circuit 35 is mounted on the vehicle 9 or the like. In the configuration (2), the resonance coil (antenna coil unit 8) provided in the power receiving side resonance circuit 35 cannot be reduced in size, but the resonance coil can be shared. Further, as illustrated in FIG. 18, when the same inductance is provided, the frequency variation with respect to the facing error d is smaller when the resonance coil is divided, so that the transmission efficiency is superior to (1). When it is not necessary to consider the mounting space of the power reception side resonance circuit 35, the configuration of (2) is preferable to (1). In the configuration (3), the electrical resistance of the resonance coil is smaller than those in (1) and (2). In terms of mountability and transmission efficiency, it does not reach the above configurations (1) and (2), but such a configuration can also be adopted.

  In the above description, the case where the power supply side resonance circuit 25 includes the antenna coil unit 8 having the plurality of antenna coils 4 has been described as an example. However, as a matter of course, the antenna coil unit 8 may be provided in the power receiving side resonance circuit 35. In this case, the pair of power supply side resonance circuits 25 includes an antenna coil unit 8 having a single antenna coil 4 or a plurality of antenna coils 4.

[Other Embodiments]
Hereinafter, other embodiments of the present invention will be described. Note that the configuration of each embodiment described below is not limited to being applied independently, and can be applied in combination with the configuration of other embodiments as long as no contradiction arises.

(1) In the said embodiment, the case where the antenna coil 4 with directivity was used was illustrated and demonstrated. When the antenna coil unit 8 is configured using a plurality of antenna coils 4, the effective area of the resonance coil is increased. For this reason, the possibility that the magnetic field generated from the resonance coil on the power supply side affects other than the resonance coil on the power reception side to be resonated becomes high. Therefore, in the above embodiment, the antenna coil 4 having directivity is described in consideration of suppressing such leakage magnetic flux. However, in order to realize the magnetic field resonance type feeding system 1 having a large tolerance of the position where the feeding side resonance circuit 25 and the receiving side resonance circuit 35 face each other and having high transmission efficiency, the antenna coil 4 having directivity is used. Obviously, the form of use is not limited. That is, the antenna coil unit 8 may be configured using the antenna coil 4 that does not have directivity as illustrated in FIGS. 4 and 5.

(2) In the above embodiment, as shown in FIG. 8, the case where both the power supply side resonance circuit 25 and the power reception side resonance circuit 35 have the antenna coil 4 having directivity is illustrated. However, when one of the sides on which the influence of the leakage magnetic flux is desired to be suppressed, the antenna coil 4 on only one of the sides may be configured with directivity. For example, if at least the power receiving resonance coil 34 includes the auxiliary coil portion 42, the influence of the magnetic field on the vehicle 9 can be suppressed. In this way, when it is sufficient that the leakage magnetic flux is suppressed only on the vehicle 9 side (the power reception side resonance circuit 35), the power supply side resonance circuit 25 is configured using the antenna coil 4 having no directivity. May be.

(3) In the said embodiment, the antenna coil 4 which has the rectangular annular main coil part 41 was illustrated. However, the shape of the antenna coil 4 (main coil portion 41) is not limited to a rectangular ring shape, and may be an annular shape or a track shape.

(4) In the above embodiment, an example in which the antenna coil 4 (main coil portion 41) is spirally formed along the reference plane PR orthogonal to the first reference axis X1 has been described. However, the configuration of the main coil portion 41 is not limited to this form. For example, the main coil portion 41 circulates along a plane parallel to the reference plane PR orthogonal to the first reference axis X1, and the diameter increases along the first reference axis X1 toward the back side axial end face PB. It may be formed in a spiral shape (tornado shape). Further, the main coil portion 41 may be formed in a cylindrical shape (spring shape) extending along the first reference axis X <b> 1 while circling with the same diameter along a plane parallel to the reference plane PR. 9 and 10 illustrate the antenna coil 4 in a form in which the main coil portion 41 is not provided with a magnetic core, but the main coil portion 41 may be provided with a core.

(5) In the said embodiment, although the form which performs wireless electric power feeding with respect to the electrical storage apparatus mounted in the vehicle 9 was illustrated, naturally this invention is not limited to application to a vehicle. For example, the present invention can also be used for power transmission by a small hydroelectric power generation, solar power generation, or small wind power generation to a general house or a building, that is, power transmission in a smart grid system.

  The present invention is used for an antenna coil unit provided in at least one of a power feeding circuit and a power receiving circuit in order to perform wireless power feeding by a magnetic field resonance method in which a resonance circuit provided in the power feeding circuit and the power receiving circuit is resonated through a magnetic field. Can do. Further, the present invention can be used for a magnetic field resonance type power feeding system configured to include this antenna coil unit.

1: Magnetic resonance type power feeding system 2: Power feeding system (power feeding circuit)
3: Power receiving system (power receiving circuit)
4: Antenna coil 5: Resonant circuit 6: Capacitor 8: Antenna coil unit 24: Feeding side resonance coil (antenna coil, antenna coil unit)
25: Power supply side resonance circuit (power supply circuit)
34: Receiving side resonance coil (antenna coil, antenna coil unit)
35: Receiving side resonance circuit (power receiving circuit)
40: Conductor line PR: Reference plane SD: Separation distance X1: First reference axis (reference axis)
S2, S3: Effective area

Claims (5)

An antenna coil unit provided in at least one of the power feeding circuit and the power receiving circuit for performing wireless power feeding by a magnetic field resonance method in which a resonance circuit provided in the power feeding circuit and the power receiving circuit is resonated via a magnetic field,
A plurality of antenna coils configured by winding a conductor wire around a reference axis are provided, and the plurality of antenna coils are adjacent to each other in a direction in which magnetic fluxes having the same phase are formed and the reference axes are parallel to each other. And an antenna coil unit configured by arranging the plurality of antenna coils side by side.   The antenna coil unit according to claim 1, wherein the plurality of antenna coils are connected in series.   3. The separation distance is set based on an amount of decrease in inductance of each antenna coil due to the influence of another adjacent antenna coil, and the plurality of antenna coils are arranged separated from each other by the separation distance. The antenna coil unit described in 1. The power feeding circuit is a magnetic resonance power feeding system configured to include the antenna coil unit according to any one of claims 1 to 3, and the power receiving circuit includes one antenna coil. And
The effective area that is the area surrounded by the outer periphery of the antenna coil viewed in the direction along the reference axis is the sum of the effective areas of the plurality of antenna coils included in the antenna coil unit of the feeder circuit. A magnetic resonance power feeding system that is set wider than the effective area of the antenna coil of the power receiving circuit.   5. The magnetic resonance power feeding system according to claim 4, wherein the effective area of each of the plurality of antenna coils constituting the antenna coil unit of the power feeding circuit is equal to the effective area of one antenna coil of the power receiving circuit. .

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