Contactless Power Transmission System

Abstract

To achieve a non-contact power transmission system that can satisfactorily reduce a leakage magnetic field, while preventing an increase in the physical constitutions of a power transmission coil and a power reception coil.SOLUTION: A non-contact power transmission system 10 transmits power from a power transmission coil 111 to a power reception coil 211 in a non-contact state. Each of the power transmission coil 111 and the power reception coil 211 includes a coil part that is a pair of coils arranged horizontally adjacent to each other, and the coils included in the coil part each have a shape wound on a horizontal surface and are configured such that the directions of magnetic fields generated by current are opposite to each other. A connection part connecting the coils included in the coil part is provided on coil outer diameter sides facing each other on the long sides of adjacent coils facing each other of the pair of coils, and the coils are bent and wound so as to be approximately point symmetrical with approximately the center of the connection part as the center of symmetry, such that the coil widths of long sides of the coils included in the pair of coils are approximately the same.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a contactless power transfer system. [Background technology]

[0002] In a contactless power transfer system that transmits power from a transmitting coil to a receiving coil without contact, the power transfer efficiency decreases when the leakage magnetic field, which is the magnetic field generated by the transmitting coil that does not intersect with the receiving coil, becomes large. Furthermore, if the leakage magnetic field spreads too much, it may affect the surrounding environment. Various technologies have been proposed to reduce the leakage magnetic field.

[0003] For example, as disclosed in Patent Document 1, a contactless power transfer system is known in which solenoid coils, whose magnetic flux directions are opposite to each other, are arranged in parallel in a direction intersecting the winding axis. In this contactless power transfer system, the power transmitting coil includes a first unit coil and a second unit coil arranged on a first surface at a distance from each other in a first direction and configured so that currents flowing therethrough have opposite phases, and the power receiving coil includes a third unit coil and a fourth unit coil arranged on a second surface parallel to the first surface at a distance from each other in the first direction and configured so that currents flowing therethrough have opposite phases. The winding axes of the first and second unit coils are arranged parallel to each other in a direction intersecting the first direction on the first surface, and the winding axes of the third and fourth unit coils are arranged parallel to each other in a direction intersecting the first direction on the second surface. The distance between the first unit coil and the second unit coil is longer than the distance between the first unit coil and the third unit coil, and the distance between the third unit coil and the fourth unit coil is longer than the distance between the second unit coil and the fourth unit coil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-47046 Summary of the Invention [Problem to be solved by the invention]

[0005] In the contactless power transfer system described in Patent Document 1, the distance between the first unit coil and the second unit coil and the distance between the third unit coil and the fourth unit coil need to be greater than the distance between the first unit coil and the third unit coil and the distance between the second unit coil and the fourth unit coil, respectively. In other words, the distance between the pair of coils included in each of the power transmitting coil and the power receiving coil needs to be greater than the distance between the power transmitting coil and the power receiving coil, which leads to an increase in the size of the power transmitting coil and the power receiving coil. Conversely, if the distance between the pair of coils included in each of the power transmitting coil and the power receiving coil is made smaller than the distance between the power transmitting coil and the power receiving coil in order to prevent the size of the power transmitting coil and the power receiving coil from increasing, reverse magnetic flux interference occurs between the pair of coils, reducing the magnetic flux linkage to the power receiving coil and decreasing the coupling coefficient between the power transmitting coil and the power receiving coil, ultimately resulting in a decrease in power transfer efficiency.

[0006] Therefore, there is a demand for a contactless power transmission system that can effectively reduce the leakage magnetic field while suppressing an increase in the size of the power transmitting coil and the power receiving coil. [Means for solving the problem]

[0007] The gist of the present disclosure is as follows.

[0008] (1) A contactless power transfer system that transfers power from a power transmitting coil to a power receiving coil in a contactless manner, each of the power transmitting coil and the power receiving coil includes a pair of coil portions arranged adjacent to each other in a horizontal direction; Each of the coils of the coil unit is wound in a horizontal plane, and is configured so that the directions of magnetic fields generated by currents are opposite to each other, The connecting portions connecting the coils of each of the coil portions are provided on the outer diameter sides of the coils facing each other on the adjacent long sides of the pair of coils facing each other, A contactless power transmission system in which the coils of a pair of coils are bent and wound so as to be approximately point symmetrical with the approximate center of the connecting portion as the center of symmetry, so that the coil widths of each long side of the coils are approximately equal. (2) Each of the power transmitting coil and the power receiving coil includes a pair of core portions that induce magnetic fields generated by the respective coils of the coil portions, The contactless power transmission system according to (1) above, wherein each of the cores of the core section is integral with each of the coils of the coil section and is arranged at a distance from each other. [Effects of the Invention]

[0009] The inventors of the present application have discovered that by forming a pair of coils included in each of the transmitting coil and the receiving coil into a circular shape wound in a horizontal plane, providing a connecting portion connecting each of the pair of coils on the outer diameter side of the opposing adjacent long sides of the pair of coils, and bending and winding the coils so that they are approximately point-symmetrical with the approximate center of the connecting portion as the center of symmetry so that the coil widths of each long side of the pair of coils are approximately equal, it is possible to suppress an increase in the physical size of the transmitting coil and the receiving coil, while suppressing magnetic field imbalance caused by the connecting wires and effectively reducing leakage magnetic fields.

[0010] According to the present disclosure, it is possible to realize a contactless power transfer system that can effectively reduce leakage magnetic fields while suppressing an increase in the size of the power transmitting coil and the power receiving coil. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a circuit diagram showing a circuit configuration of a contactless power transfer system 10 according to an embodiment of the present disclosure. [Figure 2]FIG. 2 is a conceptual diagram for explaining the configuration of a power transmission circuit 110 according to an embodiment of the present disclosure. [Figure 3] FIG. 2 is a conceptual diagram for explaining the configuration of a power receiving circuit 210 according to an embodiment of the present disclosure. [Figure 4] 1 is a conceptual diagram (part 1) for explaining the arrangement of a power transmitting circuit 110 and a power receiving circuit 210. FIG. [Figure 5] 10 is a conceptual diagram (part 2) for explaining the arrangement of the power transmitting circuit 110 and the power receiving circuit 210. FIG. [Figure 6] 4 is a flowchart illustrating an example of a process for driving and controlling a plurality of inverters 130 of the power transmission device 100 according to an embodiment of the present disclosure. [Figure 7] 10 is a conceptual diagram showing the configuration of a power transmission coil C111 of a contactless power transfer system of Comparative Example 1. FIG. [Figure 8] 10 is a conceptual diagram showing the configuration of a power receiving coil C211 of a contactless power transfer system of Comparative Example 1. FIG. [Figure 9] 10 is a diagram showing magnetic flux density distribution in the X direction (vehicle traveling direction) in the core of the power transmission coil C111 of Comparative Example 1 and the core of the power transmission coil 111 of the embodiment of the present disclosure when transmitting 30 kW of power. FIG. [Figure 10] FIG. 10 is a diagram showing measurement points of an X-direction far leakage magnetic field in a contactless power transfer system. [Figure 11] 10A and 10B are diagrams illustrating the results of comparing the far-field leakage magnetic field at a point 10 m in the X direction shown in FIG. 10 between the contactless power transfer system of Comparative Example 1 (FIGS. 7 and 8) and the contactless power transfer system 10 according to the embodiment of the present disclosure (FIGS. 1 to 5). [Figure 12] 10 is a conceptual diagram showing the configuration of a power transmission coil C311 in a contactless power transfer system of Comparative Example 2. FIG. [Figure 13] 10 is a conceptual diagram showing the configuration of a power receiving coil C411 of a contactless power transfer system of Comparative Example 2. FIG. [Figure 14] FIG. 10 is a diagram showing measurement points of a Y-direction far-field leakage magnetic field in a contactless power transfer system. [Figure 15]12A and 12B are diagrams showing the results of comparing the far-field leakage magnetic field at a point 10 m in the Y direction shown in FIG. 14 between the contactless power transfer system of comparison 2 (FIGS. 12 and 13) and the contactless power transfer system 10 according to an embodiment of the present disclosure (FIGS. 1 to 5). [Figure 16] 10 is a diagram showing the magnetic flux density distribution in the Y direction (vehicle width direction) in the core of the power transmission coil C311 of Comparative Example 2 and the core of the power transmission coil 111 of the embodiment of the present disclosure when transmitting 30 kW of power. FIG. [Figure 17] FIG. 10 is a conceptual diagram for explaining the configuration of a power transmitting circuit 110 according to a second embodiment of the present disclosure. [Figure 18] FIG. 10 is a conceptual diagram for explaining the configuration of a power receiving circuit 210 according to a second embodiment of the present disclosure. [Figure 19] 17 and 18 are diagrams illustrating the results of comparing the far-field leakage magnetic field at a point 10 m in the X direction shown in FIG. 10 between the contactless power transfer system of Comparative Example 1 (FIGS. 7 and 8) and the contactless power transfer system 10 according to the second embodiment of the present disclosure (FIGS. 17 and 18). DETAILED DESCRIPTION OF THE INVENTION

[0012] The contactless power transmission system will be described below with reference to the drawings. When the numbers, quantities, amounts, ranges, etc. of each element are mentioned in the following embodiments, the present invention is not limited to these numbers unless otherwise specified or clearly specified in principle. Furthermore, the configurations described in the following embodiments are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle. Similar components are denoted by similar reference symbols in each drawing. The scales of these drawings have been changed as appropriate to facilitate understanding. The illustrated embodiments are merely examples for carrying out the present invention, and the present invention is not limited to these embodiments.

[0013] 1. Configuration 1-1. Circuit configuration 1 is a circuit diagram showing a circuit configuration of a contactless power transmission system 10 according to an embodiment of the present disclosure. The contactless power transmission system 10 according to an embodiment of the present disclosure includes a power transmitting device 100, a power receiving device 200, a power source 300, and a battery 400.

[0014] The power transmitting device 100 and the power source 300 are typically placed on the ground, a road surface, a floor surface, etc. The power receiving device 200 and the battery 400 are typically mounted on a mobile object (a vehicle, a smartphone, etc.) to be charged.

[0015] In the contactless power transfer system 10 according to the embodiment of the present disclosure, a power transmitting coil 111 included in the power transmitting device 100 and a power receiving coil 211 included in the power receiving device 200 magnetically resonate with each other, thereby transferring power from the power transmitting coil 111 to the power receiving coil 211. That is, power is transferred by a magnetic field resonance method. As a result, power supplied from the power source 300 to the power transmitting device 100 is transferred to the power receiving device 200, and the power receiving device 200 charges the battery 400.

[0016] 1 shows one power receiving device 200 and one battery 400, but when there are multiple mobile objects to be charged, each mobile object is equipped with the power receiving device 200 and the battery 400 shown in Fig. 1. The multiple mobile objects may receive power and have their batteries 400 charged by the same power transmitting device 100.

[0017] The power supply 300 is connected to the power transmission device 100 and supplies power to the power transmission device 100. The power supply 300 is a three-phase AC power supply. For example, it is a system power supply with a phase voltage of 200 V. However, the power supply 300 may also be a single-phase AC power supply.

[0018] The battery 400 is connected to the power receiving device 200 and is charged with power by the power receiving device 200. The battery 400 is typically a rechargeable DC power supply such as a lithium ion battery or a nickel-metal hydride battery.

[0019] The power transmitting device 100 includes a power transmitting circuit 110, an immittance filter 120, an inverter 130, and an AC / DC converter 140. The power transmitting circuit 110, the immittance filter 120, the inverter 130, and the AC / DC converter 140 are configured to be cascade-connected.

[0020] The AC-DC converter 140 rectifies and transforms AC power supplied from the power supply 300 and outputs DC power to the inverter 130. The AC-DC converter 140 is typically configured with a rectifier circuit including a diode and a capacitor, and a step-up / step-down circuit including a semiconductor switching element (IGBT, MOSFET, etc.). The output voltage, drive, and stop of the AC-DC converter 140 are controlled by a control device (not shown) controlling the semiconductor switching element. The control device has one or more CPUs (Central Processing Units) and their peripheral circuits. The control device may further have an arithmetic circuit such as a logic operation unit or a numerical operation unit. The control device executes various processes based on software programs.

[0021] The inverter 130 converts the DC power output from the AC / DC converter 140 into AC power of a predetermined frequency, and outputs the AC power to the power transmission circuit 110 via the immittance filter 120. The inverter 130 converts the DC power so that the frequency of the AC power to be output is equivalent to a resonant frequency of the power transmission circuit 110, which will be described later. The frequency of the AC power output by the inverter 130 (the resonant frequency of the power transmission circuit 110) is a high frequency of, for example, about 85 kHz.

[0022] The inverter 130 is typically configured with a single-phase full-bridge circuit including semiconductor switching elements. The inverter 130 converts DC power into AC power of a predetermined frequency by performing switching control using pulse width modulation (PWM) or the like by a control device (not shown). The inverter 130 is also controlled to be driven and stopped by the control device.

[0023] The immittance filter 120 reduces electromagnetic noise in the output power of the inverter 130. The immittance filter 120 is configured by a coil and a capacitor as shown in FIG.

[0024] The power transmitting circuit 110 is a resonant circuit configured with a power transmitting coil 111 and capacitors C11 and C12. Coils L11 and L12 in the power transmitting coil 111 have capacitors C11 and C12 connected to one end, respectively. Capacitor C11, coil L11, coil L12, and capacitor C12 are connected in series in this order, making the power transmitting circuit 110 a series resonant circuit. Capacitors C11 and C12 are resonant capacitors that provide capacitance to the resonant circuit (power transmitting circuit 110). Capacitors C11 and C12 have approximately the same capacitance. Details of the power transmitting circuit 110 and the power transmitting coil 111 will be described later.

[0025] The resonant frequency of the power transmitting circuit 110 is equal to the frequency of the output power of the inverter 130. The power transmitting coil 111 magnetically resonates with the power receiving coil 211 (described later) due to the power output from the inverter 130 at the resonant frequency. Then, power is transmitted from the power transmitting coil 111 to the power receiving coil 211.

[0026] When transmitting power to a moving mobile object, a plurality of power transmission coils 111 (and thus power transmission circuits 110) are arranged along the path of the mobile object. For example, when transmitting power to a traveling vehicle, a plurality of power transmission coils 111 are arranged on the road along the path of the vehicle. In this case, it is necessary to appropriately switch the power transmission coil 111 that transmits power according to the movement of the mobile object. For this reason, in addition to the power transmission circuit 110, a plurality of immittance filters 120 and inverters 130 are arranged along the path of the mobile object. On the other hand, it is not necessary to arrange a plurality of AC / DC converters 140 as long as the DC power to be output is supplied to each of the plurality of inverters 130.

[0027] To illustrate this, FIG. 1 shows a case where the power transmitting device 100 includes a plurality of power transmitting circuits 110, a plurality of immittance filters 120, and a plurality of inverters 130. As shown in FIG. 1, a plurality of circuits, each of which is a cascade connection of the power transmitting circuits 110, the immittance filters 120, and the inverters 130, are connected in parallel to the output terminal of the AC / DC converter 140. Note that the plurality of power transmitting circuits 110, the immittance filters 120, and the inverters 130 are the same as those described above. Furthermore, in order to distinguish the plurality of power transmitting circuits 110, the immittance filters 120, and the inverters 130 from one another, symbols (A, B, ...) are added to the respective reference numerals. However, the power transmitting device 100 according to this embodiment may be configured with a single power transmitting circuit 110, an immittance filter 120, and an inverter 130.

[0028] The power receiving device 200 includes a power receiving circuit 210, an immittance filter 220, a rectifier circuit 230, and a smoothing capacitor C24. The power receiving circuit 210, the immittance filter 220, and the rectifier circuit 230 are configured to be cascaded. The smoothing capacitor C24 is connected to the output terminal of the rectifier circuit.

[0029] The power receiving circuit 210 is a resonant circuit configured with a power receiving coil 211 and capacitors C21 and C22. Coils L21 and L22 in the power receiving coil 211 have capacitors C21 and C22 connected to one end, respectively. Capacitor C21, coil L21, coil L22, and capacitor C22 are connected in this order, and the power receiving circuit 210 is a series resonant circuit. Capacitors C21 and C22 are resonant capacitors that provide capacitance to the resonant circuit (power receiving circuit 210). Capacitors C21 and C22 have approximately the same capacitance. Details of the power receiving circuit 210 and the power receiving coil 211 will be described later.

[0030] The resonant frequency of the power receiving circuit 210 is equal to the frequency of the output power of the inverter 130 (the resonant frequency of the power transmitting circuit 110). The power receiving coil 211 magnetically resonates with the power transmitting coil 111, and receives the power transmitted from the power transmitting coil 111.

[0031] The immittance filter 220 reduces electromagnetic noise in the power received by the power receiving circuit 210. The immittance filter 220 is configured with a coil and a capacitor as shown in FIG.

[0032] The rectifier circuit 230 converts the power received by the power receiving circuit 210 into DC power and outputs it. The rectifier circuit 230 is typically a single-phase full-wave rectifier circuit.

[0033] The smoothing capacitor C24 smoothes the DC power output by the rectifier circuit 230. The DC power smoothed by the smoothing capacitor C24 becomes the charging power for the battery 400.

[0034] 1-2. Power transmission circuit, power receiving circuit 1-2-1. Power transmission circuit Fig. 2 is a conceptual diagram for explaining the configuration of a power transmission circuit 110 according to an embodiment of the present disclosure. Fig. 2 shows a plan view of the power transmission circuit 110 located on a horizontal plane (XY plane) as seen from the vertical direction (Z-axis direction), a side view as seen from the horizontal-longitudinal direction (X-axis direction), and a perspective view. As described above, the power transmission circuit 110 is a resonant circuit configured by the power transmission coil 111 and capacitors C11 and C12.

[0035] The power transmission coil 111 includes a first coil portion (coils L11 and L12) that is a pair of coils, a first core portion (cores MM11 and MM12) that is a pair of cores, and an aluminum plate PL1. The coils L11 and L12 and the cores MM11 and MM12 are held in place by a resin member or the like (not shown).

[0036] As shown in Fig. 2, each of the coils L11 and L12 of the first coil section has a circular shape wound in a horizontal plane (XY plane). One end of each of the coils L11 and L12 is connected by a connecting portion A1, and the coils are wound so that the magnetic fields generated by current flow in opposite directions. That is, the coil L11 generates a magnetic field that is, for example, upward relative to the vertical direction (Z-axis direction), and the coil L12 generates a magnetic field that is, for example, downward relative to the vertical direction (Z-axis direction).

[0037] Each of the coils L11 and L12 of the first coil section has two long coil sides (coil sides along the X-axis direction, which is the long axis direction in FIG. 2) and two short coil sides (coil sides along the Y-axis direction, which is the short axis direction in FIG. 2). The coils L11 and L12 of the first coil section are connected by a connecting portion A1 at the positions of the opposing outer diameter sides and coil long sides of each of the coils L11 and L12. In other words, the connecting portion A1 is provided on the opposing outer diameter sides of the adjacent coil long sides of the pair of coils L11 and L12 that face each other (within the region sandwiched between the coils L11 and L12).

[0038] Because the short sides of the coils L11 and L12 of the first coil section generate an X-direction magnetic field, if the connecting portion were located on the short sides, the X-direction magnetic fields generated by the coils L11 and L12 would be unbalanced, increasing the far-field leakage magnetic field. Therefore, in an embodiment of the present disclosure, the connecting portion A1 connecting the coils L11 and L12 is located on the long sides of the coils rather than on the short sides. As a result, the X-direction magnetic fields generated on the short sides of the coils where the connecting portion A1 is not located are the same in magnitude but opposite in direction for the coils L11 and L12, effectively suppressing the increase in the X-direction far-field leakage magnetic field.

[0039] Furthermore, when forming the connecting portion A1 on the long sides of the pair of coils L11 and L12, the coil widths of the opposing long sides (WI11 and WI12) and the non-opposing long sides (WO11 and WO12) are approximately equal, that is, the coil widths of the long sides of the pair of coils L11 and L12 are approximately equal (WO11 = WI11 = WI12 = WO12), and a portion of the long sides of the coils near the connecting portion A1 is appropriately bent to be approximately point-symmetric with the approximate center of the connecting portion A1 as the center of symmetry (point of symmetry). As a result, the Y-direction magnetic fields generated at the long sides of coils L11 and L12 are the same magnitude but opposite in direction for coils L11 and L12, effectively suppressing an increase in the Y-direction far-field leakage magnetic field.

[0040] The cores MM11 and MM12 of the first core unit are made of a magnetic material that induces the magnetic field generated by the coils L11 and L12 of the first coil unit, and are typically made of ferrite.

[0041] Furthermore, each core MM11 and MM12 of the first core section is integral with each coil L11 and L12 of the first coil section, and is arranged adjacent to each other with a distance AW1 (referred to as the "first inter-core distance AW1") in the horizontal direction (Y-axis direction).

[0042] The aluminum plate PL1 is disposed under the coils L11 and L12 and the cores MM11 and MM12 to reduce the influence of external magnetic fields on the power transmitting circuit 110.

[0043] 1-2-2. Power receiving circuit Fig. 3 is a conceptual diagram for explaining the configuration of a power receiving circuit 210 according to an embodiment of the present disclosure. Fig. 3 shows a plan view of the power receiving circuit 210 located on a horizontal plane (XY plane) as seen from the vertical direction (Z-axis direction), a side view as seen from the horizontal-longitudinal direction (X-axis direction), and a perspective view. As described above, the power receiving circuit 210 is a resonant circuit configured by the power receiving coil 211 and capacitors C21 and C22.

[0044] The power receiving coil 211 includes a second coil portion (coils L21 and L22) that is a pair of coils, a second core portion (cores MM21 and MM22) that is a pair of cores, and an aluminum plate PL2. The coils L21 and L22 and the cores MM21 and MM22 are held in place by a resin member or the like (not shown).

[0045] As shown in Fig. 3, each of the coils L21 and L22 of the second coil section has a circular shape wound in a horizontal plane (XY plane). Furthermore, one end of each of the coils L21 and L22 is connected by a connecting portion A2, and the coils are wound so that the magnetic fields generated by the current flow in opposite directions. This allows the coils L21 and L22 of the second coil to appropriately receive the magnetic fields generated in opposite directions by the coils L11 and L12 of the first coil section.

[0046] Each of the coils L21 and L22 of the second coil section has two long coil sides (coil sides along the X-axis direction, which is the long axis direction in FIG. 3) and two short coil sides (coil sides along the Y-axis direction, which is the short axis direction in FIG. 3). The coils L21 and L22 of the second coil section are preferably connected by a connecting portion A2 at the positions of the opposing outer diameter sides and the coil long sides of each of the coils L21 and L22. That is, the connecting portion A2 is provided on the opposing outer diameter sides of the adjacent coil long sides of the pair of coils L21 and L22 that face each other (within the region sandwiched between the coils L21 and L22).

[0047] Because the short sides of coils L11 and L22 of the second coil section generate an X-direction magnetic field, if the connecting portion were located on the short sides, the X-direction magnetic field received by coils L21 and L22 would be unbalanced, increasing the far-field leakage magnetic field. Therefore, in an embodiment of the present disclosure, the connecting portion A2 connecting coils L21 and L22 is located on the long sides of the coils rather than on the short sides. As a result, the X-direction magnetic field received by the short sides of the coils where the connecting portion A2 is not located is the same magnitude but opposite in direction for coils L21 and L22, effectively suppressing the increase in the X-direction far-field leakage magnetic field.

[0048] Furthermore, when forming a connecting portion A2 on the long sides of the pair of coils L21 and L22, a portion of the long sides of the coils near the connecting portion A2 is appropriately bent so that the coil widths of the opposing long sides (WI21 and WI22) and the coil widths of the non-opposing long sides (WO21 and WO22) are approximately equal, that is, so that the coil widths of the long sides of the pair of coils L21 and L22 are approximately equal (WO21 = WI21 = WI22 = WO22). This ensures that the Y-direction magnetic fields of the long sides of coils L21 and L22 are the same magnitude but opposite in direction, effectively suppressing an increase in the Y-direction far-field leakage magnetic field.

[0049] 2 and 3, the coil wiring extending from coil L21 to coil L22 via connecting portion A2 in the power receiving coil 211 has a similar routing shape to the coil wiring extending from coil L11 to coil L12 via connecting portion A1 in the power transmitting coil 111 when the first coil portion (coils L11 and L12) and the second coil portion (coils L21 and L22) of the power receiving coil 211 face each other. 2 and 3, when the first coil section (coils L11 and L12) and the second coil section (coils L21 and L22) of the power receiving coil 211 face each other, the lead wires extending from the second coil section (coils L21 and L22) of the power receiving coil 211 to the capacitors C21 and C22 are arranged to have a similar routing shape to the lead wires extending from the first coil section (coils L11 and L12) of the power transmitting coil 111 to the capacitors C11 and C12, respectively. This makes it possible to more effectively suppress increases in the X-direction far leakage magnetic field and the Y-direction far leakage magnetic field.

[0050] Furthermore, the length of the first coil section in the long axis direction (X-axis direction in FIG. 2) is longer than the length of the second coil section in the long axis direction (X-axis direction in FIG. 3). On the other hand, the lengths of the first coil section and the second coil section in the short axis direction (Y-axis direction in FIGS. 2 and 3) are equal. This makes it possible to suppress pulsation in the power received by the power receiving coil 211.

[0051] The cores MM21 and MM22 of the second core portion are made of a magnetic material that induces the magnetic field generated by the coils L21 and L22 of the second coil portion, and are typically made of ferrite.

[0052] Furthermore, each core MM21 and MM22 of the second core section is integral with each coil L21 and L22 of the second coil section, and is arranged adjacent to each other with a distance AW2 (referred to as the "second core distance AW2") in the horizontal direction (Y-axis direction).

[0053] Here, to improve transmission efficiency, it is desirable that the second inter-core distance AW2 be approximately equal to the first inter-core distance AW1. Hereinafter, it is assumed that the first inter-core distance AW1 and the second inter-core distance AW2 are approximately equal.

[0054] The aluminum plate PL2 is disposed under the coils L21 and L22 and the cores MM21 and MM22 to reduce the influence of an external magnetic field on the power receiving circuit 210.

[0055] 1-2-3. Placement The first coil section (coils L11 and L12) and the second coil section (coils L21 and L22) are arranged to face each other. FIGS. 4 and 5 are conceptual diagrams for explaining the arrangement of the power transmitting circuit 110 and the power receiving circuit 210. FIG. 4 shows a perspective view. FIG. 5 shows a plan view seen from the vertical direction (Z-axis direction), a cross-sectional view seen from the horizontal-longitudinal direction (X-axis direction), and a cross-sectional view seen from the horizontal-lateral direction (Y-axis direction). FIGS. 4 and 5 also show a case where the power transmitting device 100 includes multiple power transmitting circuits 110, and five first coil sections are shown as an example. That is, they show an arrangement when transmitting power to a moving object. Note that FIGS. 4 and 5 omit some of the configurations of the power transmitting circuit 110 and the power receiving circuit 210 described in FIGS. 2 and 3.

[0056] As shown in FIG. 5, the first coil unit and the second coil unit face each other across a distance AG in the vertical direction (hereinafter also referred to as the "power transmission / reception distance AG"). Also, as shown in FIG. 4, multiple first coil units are attached in a series to an aluminum plate PL1 and placed on the ground, road surface, floor surface, etc. The direction in which the first coil units are attached (X-axis direction) typically corresponds to the direction of travel of the moving object. The second coil unit is attached to an aluminum plate PL2 and is mounted on the moving object to be charged. Surface FL indicates the part of the moving object on which the second coil unit is mounted. If the moving object is a vehicle, for example, surface FL is the bottom of the vehicle body.

[0057] As described above, the length per pitch of the multiple first coil sections is longer than the length in the major axis direction (X-axis direction) of the second coil section, which makes it possible to suppress pulsation in the power received by the power receiving coil 211 per pitch.

[0058] 2. Operation In order to transmit power to a moving mobile object, it is necessary to appropriately control each of the inverters 130 associated with the multiple power transmitting coils 111 according to the position of the mobile object. Fig. 6 is a flowchart showing an example of a process for driving and controlling the multiple inverters 130 of the power transmitting device 100 according to an embodiment of the present disclosure.

[0059] The process shown in Fig. 6 is executed by a control device associated with the inverter 130. The process shown in Fig. 6 is started when a condition for driving the first inverter 130 is satisfied. Here, the first inverter 130 is the inverter 130 associated with the power transmission coil 111 that transmits power to the moving object first. For example, when the moving object is a vehicle and the power transmission coils 111 are arranged in a row on a road, this is the inverter 130 associated with the power transmission coil 111 that the vehicle passes first. The condition for driving the first inverter 130 is, for example, when it is detected that the moving object has passed a point just before the position of the power transmission coil 111 that the vehicle will pass first and at which there is no branch before passing the power transmission coil 111.

[0060] In step S100, the control device sets N, a value indicating the inverter 130 to be controlled, to 1. N corresponds to the order of the inverters 130 associated with the power transmission coils 111 arranged in series, and N=1 corresponds to the inverter 130 associated with the power transmission coil 111 that first transmits power to the mobile object. After step S100, the process proceeds to step S110.

[0061] In step S110, the control device drives the Nth inverter 130 with a small voltage output. Immediately after the start of the process, N=1, so the first inverter 130 is driven with a small output voltage. After step S110, the process proceeds to step S120.

[0062] In step S120, the control device determines whether the output current (inverter current) of the Nth inverter 130 exceeds a predetermined value. The inverter current has a characteristic that it increases as the power receiving coil 211 approaches the power transmitting coil 111 and decreases as the power receiving coil 211 moves away from the power transmitting coil 111. Therefore, when a moving object passes the power transmitting coil 111, the inverter current increases until the moving object reaches a position closest to the power transmitting coil 111, and then decreases. In other words, when the Nth inverter current exceeds a predetermined value, it can be determined that the moving object has come sufficiently close to the Nth inverter 130. The predetermined value is a value that is provided to the program in advance and is optimally determined through experiments, etc.

[0063] If the Nth inverter current exceeds the predetermined value (step S120; Yes), the process proceeds to step S130. If the Nth inverter current does not exceed the predetermined value (step S120; No), the process of step S120 is executed again in the next execution cycle.

[0064] In step S130, the control device increases the output voltage of the Nth inverter 130. This is because the moving object is close enough to the Nth inverter 130 to sufficiently transmit power by the power transmitting coil 111 associated with the Nth inverter 130. After step S130, the process proceeds to step S140.

[0065] In step S140, the control device determines whether the Nth inverter current is below a predetermined value. As described above, when the Nth inverter current falls below the predetermined value, it can be determined that the moving object has moved a certain distance away from the Nth inverter 130. The predetermined value is a value that is provided in advance to the program and is a value that is optimally determined through experiments or the like. The predetermined value may be the same as or different from the predetermined value in step S120.

[0066] If the Nth inverter current is below the predetermined value (step S140; Yes), the process proceeds to step S150. If the Nth inverter current is not below the predetermined value (step S140; No), the process of step S140 is executed again in the next execution cycle.

[0067] In step S150, the control device reduces the output voltage of the Nth inverter 130. This is because the moving object is at a certain distance from the Nth inverter 130 and the effect of power transmission by the power transmission coil 111 associated with the Nth inverter 130 is small. At this time, the Nth inverter 130 may be stopped, and power transmission by the power transmission coil 111 associated with the Nth inverter 130 may be stopped. After step S150, the process proceeds to step S160.

[0068] In step S160, the control device determines whether the Nth inverter 130 is the terminal end. This is done, for example, by providing the number k of power transmission coils 111 to be arranged to the program in advance or by acquiring the number k and determining whether N is k. If the Nth inverter 130 is the terminal end (step S160; Yes), the process ends. If the Nth inverter 130 is not the terminal end (step S160; No), the process proceeds to step S170.

[0069] In step S170, the control device increments N. After step S170, the process returns to step S110 in the next execution cycle, and the process is repeated.

[0070] By the above-described processing, it is possible to control each of the multiple inverters 130 depending on the position of the moving object. Note that the processing shown in Fig. 6 is an example, and appropriate processing may be applied depending on the environment to which the contactless power transfer system 10 according to the embodiment of the present disclosure is applied.

[0071] 3.Characteristics In the contactless power transmission system 10 according to an embodiment of the present disclosure, the pair of coils included in each of the transmitting coil 111 and the receiving coil 211 are formed into a circular shape wound in a horizontal plane, and the connecting portions A1 and A2 connecting the respective coils of the pair of coils are provided on the outer diameter sides of the coils facing each other on the adjacent long sides of the pair of coils, and the coils are bent and wound in approximately point symmetry with the approximate center of the connecting portions A1 and A2 as the center of symmetry so that the coil widths of the respective long sides of the pair of coils are approximately equal, thereby making it possible to effectively reduce the leakage magnetic field.

[0072] Below, a comparison is shown between the leakage magnetic field in the contactless power transfer system 10 according to the embodiment of the present disclosure and the leakage magnetic field in a contactless power transfer system that does not use a pair of coils integrated with a pair of cores. In the contactless power transfer system 10 according to the embodiment of the present disclosure, the power transmitting circuit 110 and the power receiving circuit 210 are assumed to have the configuration and arrangement shown in FIGS. 1 to 5.

[0073] Fig. 7 is a conceptual diagram showing the configuration of the power transmitting coil C111 of the contactless power transfer system of Comparative Example 1. Fig. 8 is a conceptual diagram showing the configuration of the power receiving coil C211 of the contactless power transfer system of Comparative Example 1.

[0074] As shown in FIG. 7, the power transmission coil C111 of the contactless power transmission system of Comparative Example 1 includes a pair of coils, a first coil portion (coils CL11 and CL12), a pair of cores, a first core portion (cores CMM11 and CMM12), and an aluminum plate CPL1. As shown in FIG. 7, the coils CL11 and CL12 have a circular shape wound in a horizontal plane (XY plane). The coils CL11 and CL12 are wound so that the magnetic fields generated by currents are in opposite directions. That is, the coil CL11 generates a magnetic field directed upward relative to the vertical direction (Z-axis direction), and the coil CL12 generates a magnetic field directed downward relative to the vertical direction (Z-axis direction). The coils CL11 and CL12 of the first coil portion are connected to each other by a connecting portion A3 on the inner diameter side of each of the coils CL11 and CL12.

[0075] As shown in Fig. 8, the power receiving coil C211 of the contactless power transfer system of Comparative Example 1 includes a second coil portion (coils CL21 and CL22) that is a pair of coils, a second core portion (cores CMM21 and CMM22) that is a pair of cores, and an aluminum plate CPL2. As shown in Fig. 8, the coils CL21 and CL22 have a circular shape wound in a horizontal plane (XY plane). Furthermore, the coils CL21 and CL22 are wound so that the magnetic fields generated by currents are in opposite directions. The coils CL21 and CL22 of the second coil portion are connected to each other on the inner diameter side of each coil CL21 and CL22 by a connecting portion A4.

[0076] 9 is a diagram showing the magnetic flux density distribution in the X direction (vehicle traveling direction) in the core of the power transmission coil C111 of Comparative Example 1 and the core of the power transmission coil 111 of the embodiment of the present disclosure when transmitting 30 kW of power. As shown in Fig. 9, in the core of the power transmission coil C111 of Comparative Example 1, due to the influence of the connecting portion A3 provided on the inner diameter side of each of the coils CL11 and CL12, the X direction magnetic fields generated by the pair of coils CL11 and CL12 are different in magnitude and in opposite directions, resulting in asymmetric (unbalanced) magnetic fields. In contrast, in the core of the power transmission coil 111 of the embodiment of the present disclosure, the X direction magnetic fields generated by the pair of coils L11 and L12 are the same in magnitude but in opposite directions, resulting in symmetric magnetic fields.

[0077] FIG. 10 is a diagram illustrating measurement points of the X-direction far-side leakage magnetic field in a contactless power transfer system. For example, if the moving object to be charged is a vehicle and the power transmission coils (first coil units) are arranged in a row on a road along the vehicle's travel path, a far-side point, for example, about 10 m away from the center of the power transmission coil in the vehicle's direction of travel (X-axis direction), is set as the measurement point of the X-direction far-side leakage magnetic field. FIG. 11 is a diagram illustrating a comparison result of the far-side leakage magnetic field at a 10 m point in the X-direction shown in FIG. 10 between the contactless power transfer system of Comparative Example 1 ( FIGS. 7 and 8 ) and the contactless power transfer system 10 ( FIGS. 1 to 5 ) according to an embodiment of the present disclosure. As shown in FIG. 11 , the contactless power transfer system 10 ( FIGS. 1 to 5 ) according to an embodiment of the present disclosure has a far-side leakage magnetic field that is approximately 7 dB lower than the contactless power transfer system of Comparative Example 1 ( FIGS. 7 and 8 ).

[0078] Fig. 12 is a conceptual diagram showing the configuration of a power transmitting coil C311 in the contactless power transfer system of Comparative Example 2. Fig. 13 is a conceptual diagram showing the configuration of a power receiving coil C411 in the contactless power transfer system of Comparative Example 2.

[0079] The power transmission coil C311 of the contactless power transmission system of comparison 2 shown in FIG. 12 differs from the power transmission coil 111 of the contactless power transmission system 10 of the embodiment of the present disclosure in that it does not have a bending portion that makes the coil widths of the long sides of the pair of coils CL31 and CL32 approximately equal.

[0080] As shown in Fig. 12, the power transmission coil C311 of the contactless power transfer system of Comparative Example 2 includes a pair of coils, a first coil portion (coils CL31 and CL32), a pair of cores, a first core portion (cores CMM31 and CMM32), and an aluminum plate CPL1. As shown in Fig. 12, the coils CL31 and CL32 have a circular shape wound in a horizontal plane (XY plane). Furthermore, one end of each of the coils CL31 and CL32 is connected, and the coils are wound so that the magnetic fields generated by currents are in opposite directions. That is, the coil CL31 generates a magnetic field directed upward relative to the vertical direction (Z-axis direction), and the coil CL32 generates a magnetic field directed downward relative to the vertical direction (Z-axis direction). The coils CL31 and CL32 of the first coil portion are connected on the opposing outer diameter sides of the adjacent opposing coil long sides of the pair of coils CL31 and CL32 (within the region sandwiched between the coils CL31 and CL32).

[0081] The power transmission coil C311 of comparison 2 does not have a bent portion like the embodiments of the present disclosure, and therefore, due to the presence of a portion on the long sides of the coil connecting coils CL31 and CL32, the coil widths of the non-opposing long sides of the coil (WO31 and WO32) are larger than the coil widths of the opposing long sides of the coil (WI31 and WI32).

[0082] The cores CMM31 and CMM32 of the first core portion are made of a magnetic material that induces the magnetic field generated by the coils CL31 and CL32 of the first coil portion, respectively. The cores CMM31 and CMM32 are typically made of ferrite.

[0083] Furthermore, the cores CMM31 and CMM32 of the first core portion are integral with the coils CL31 and CL32 of the first coil portion, respectively, and are arranged adjacent to each other with a distance in the horizontal direction (Y-axis direction).

[0084] The aluminum plate CPL1 is disposed below the coils CL31 and CL32 and the cores CMM31 and CMM32 to reduce the influence of an external magnetic field on the transmitting coil C311.

[0085] The receiving coil C411 of the contactless power transmission system of comparison 2 shown in Figure 13 differs from the receiving coil 211 of the contactless power transmission system 10 of the embodiment of the present disclosure in that it does not have a bending portion that makes the coil widths of the long sides of the pair of coils CL41 and CL42 approximately equal.

[0086] As shown in Fig. 13, the power receiving coil C411 of the contactless power transfer system of Comparative Example 2 includes a second coil portion (coils CL41 and CL42) that is a pair of coils, a second core portion (cores CMM41 and CMM42) that is a pair of cores, and an aluminum plate CPL2. As shown in Fig. 13, the coils CL31 and CL32 have a circular shape wound in a horizontal plane (XY plane). Furthermore, one end of the coils CL41 and CL42 are connected to each other, and the coils are wound so that the magnetic fields generated by currents are in opposite directions. The coils CL41 and CL42 of the second coil portion are connected on the opposing outer diameter sides of the adjacent long sides of the pair of coils CL41 and CL42 (within the region sandwiched between the coils CL41 and CL42).

[0087] The receiving coil C411 of comparison 2 does not have a bending portion like the embodiments of the present disclosure, and therefore, due to the presence of a portion on the long sides of the coil connecting coil CL41 and coil CL42, the coil widths of the non-opposing long sides of the coil (WO41 and WO42) are larger than the coil widths of the opposing long sides of the coil (WI41 and WI42).

[0088] The cores CMM41 and CMM42 of the second core unit are made of a magnetic material that induces the magnetic field generated by the coils CL41 and CL42 of the second coil unit, respectively. The cores CMM41 and CMM42 are typically made of ferrite.

[0089] Furthermore, the cores CMM41 and CMM42 of the second core portion are integral with the coils CL41 and CL42 of the second coil portion, respectively, and are arranged adjacent to each other with a distance in the horizontal direction (Y-axis direction).

[0090] The aluminum plate CPL2 is disposed below the coils CL41 and CL42 and the cores CMM41 and CMM42 to reduce the influence of an external magnetic field on the receiving coil C411.

[0091] Fig. 14 is a diagram showing measurement points of the Y-direction far-side leakage magnetic field in a contactless power transfer system. For example, in a case where the moving object to be charged is a vehicle and the power transmission coils (first coil units) are arranged in a row on a road along the vehicle's travel path, a far-side point, for example, about 10 m away from the center of the power transmission coil in the vehicle width direction (Y-axis direction) that is offset by 90 degrees from the vehicle's direction of travel (X-axis direction), is set as the measurement point of the Y-direction far-side leakage magnetic field. Fig. 15 is a diagram showing a comparison result of the far-side leakage magnetic field at a point 10 m away in the Y direction shown in Fig. 14 between the contactless power transfer system of Comparative Example 2 (Figs. 12 and 13) and the contactless power transfer system 10 (Figs. 1 to 5) according to an embodiment of the present disclosure. As shown in Figure 15, the contactless power transmission system 10 (Figures 1 to 5) according to the embodiment of the present disclosure has the same coil width on the long side of each coil, and therefore can reduce the far-field leakage magnetic field by approximately 7 dB compared to the contactless power transmission system of comparison 2 (Figures 12 and 13).

[0092] 16 is a diagram showing the magnetic flux density distribution in the Y direction (vehicle width direction) in the core of the power transmission coil C311 of Comparative Example 2 and the core of the power transmission coil 111 of the embodiment of the present disclosure when transmitting 30 kW of power. In the core of the power transmission coil 111 of the embodiment of the present disclosure, the coil width WO11 of coil L11 and the coil width WI12 of coil L12 are approximately equal, so as shown in FIG. 16, the magnetic fields generated by the pair of coils L11 and L12 are approximately the same magnitude but opposite in direction, resulting in little asymmetry. In contrast, the coil width WO31 of coil CL31 and the coil width WI22 of coil CL32 are different, so the magnetic fields generated by the pair of coils CL31 and CL32 are different magnitudes but opposite in direction, reducing the cancellation effect of the opposing magnetic fields between the adjacent coils CL31 and CL32, resulting in large asymmetry and imbalance.

[0093] 4. Embodiment 2 Next, a second embodiment of the present disclosure will be described in which the connecting portions are provided on the short sides of the pair of coils L11 and L12.

[0094] 4-1. Power transmission circuit, power receiving circuit 4-1-1. Power transmission circuit Fig. 17 is a conceptual diagram for explaining the configuration of a power transmission circuit 110 according to a second embodiment of the present disclosure. Fig. 17 shows a plan view of the power transmission circuit 110 located on a horizontal plane (XY plane) as seen from the vertical direction (Z-axis direction), a side view as seen from the horizontal-longitudinal direction (X-axis direction), and a perspective view. The power transmission circuit 110 is a resonant circuit configured with a power transmission coil 111 and capacitors C11 and C12.

[0095] The power transmission coil 111 includes a first coil portion (coils L31 and L32) that is a pair of coils, a first core portion (cores MM31 and MM32) that is a pair of cores, and an aluminum plate PL1. The coils L31 and L32 and the cores MM31 and MM32 are held in place by a resin member or the like (not shown).

[0096] As shown in Fig. 17, each of the coils L31 and L32 of the first coil section has a circular shape wound in a horizontal plane (XY plane). One end of each of the coils L31 and L32 is connected by a connecting portion A5, and the coils are wound so that the magnetic fields generated by current flow in opposite directions. That is, the coil L31 generates a magnetic field that is, for example, upward relative to the vertical direction (Z-axis direction), and the coil L32 generates a magnetic field that is, for example, downward relative to the vertical direction (Z-axis direction).

[0097] Each of the coils L31 and L32 of the first coil section has two long coil sides (coil sides along the X-axis direction, which is the long axis direction in FIG. 17) and two short coil sides (coil sides along the Y-axis direction, which is the short axis direction in FIG. 17). The coils L31 and L32 of the first coil section are connected by a connecting portion A5 at the positions of the short coil sides on the opposing outer diameter sides of the pair of coils L31 and L32 (within the area sandwiched between the coils L31 and L32).

[0098] The cores MM31 and MM32 of the first core unit are made of a magnetic material that induces the magnetic field generated by the coils L31 and L32 of the first coil unit, and are typically made of ferrite.

[0099] Furthermore, the cores MM31 and MM32 of the first core portion are integral with the coils L31 and L32 of the first coil portion, respectively, and are arranged adjacent to each other with a distance in the horizontal direction (Y-axis direction).

[0100] The aluminum plate PL1 is disposed under the coils L31 and L32 and the cores MM31 and MM32 to reduce the influence of external magnetic fields on the power transmitting circuit 110.

[0101] 4-1-2. Power receiving circuit Fig. 18 is a conceptual diagram for explaining the configuration of a power receiving circuit 210 according to the second embodiment of the present disclosure. Fig. 18 shows a plan view of the power receiving circuit 210 located on a horizontal plane (XY plane) as seen from the vertical direction (Z-axis direction), a side view as seen from the horizontal-longitudinal direction (X-axis direction), and a perspective view. As described above, the power receiving circuit 210 is a resonant circuit configured by the power receiving coil 211 and capacitors C21 and C22.

[0102] The power receiving coil 211 includes a second coil portion (coils L41 and L42) that is a pair of coils, a second core portion (cores MM41 and MM42) that is a pair of cores, and an aluminum plate PL2. The coils L41 and L42 and the cores MM41 and MM42 are held in place by a resin member or the like (not shown).

[0103] As shown in Fig. 18, each of the coils L41 and L42 of the second coil section has a circular shape wound in a horizontal plane (XY plane). Furthermore, one end of each of the coils L41 and L42 is connected by a connecting portion A6, and the coils are wound so that the magnetic fields generated by the current flow in opposite directions. This allows the coils L41 and L42 of the second coil section to appropriately receive the magnetic fields generated in opposite directions by the coils L31 and L32 of the first coil section.

[0104] Coils L41 and L42 of the second coil section each have two long coil sides (coil sides along the X-axis direction, which is the long axis direction in FIG. 18) and two short coil sides (coil sides along the Y-axis direction, which is the short axis direction in FIG. 18). Coils L41 and L42 of the second coil section are connected by a connecting portion A6 at the positions of the short coil sides on the opposing outer diameter sides of the pair of coils L41 and L42 (within the area sandwiched between coils L41 and L42).

[0105] 17 and 18, the coil wiring extending from coil L41 to coil L42 via connecting portion A6 in the power receiving coil 211 has a similar routing shape to the coil wiring extending from coil L31 to coil L32 via connecting portion A5 in the power transmitting coil 111 when the first coil portion (coils L31 and L32) and the second coil portion (coils L41 and L42) of the power receiving coil 211 face each other. 17 and 18, when the first coil section (coils L31 and L32) and the second coil section (coils L41 and L42) of the power receiving coil 211 face each other, the lead wires extending from the second coil section (coils L41 and L42) of the power receiving coil 211 to the capacitors C21 and C22 are arranged to have a similar routing shape to the lead wires extending from the first coil section (coils L31 and L32) of the power transmitting coil 111 to the capacitors C11 and C12, respectively. This makes it possible to more effectively suppress increases in the X-direction far leakage magnetic field and the Y-direction far leakage magnetic field.

[0106] Furthermore, the length of the first coil section in the major axis direction (X-axis direction in FIG. 17) is longer than the length of the second coil section in the major axis direction (X-axis direction in FIG. 18). On the other hand, the lengths of the first coil section and the second coil section in the minor axis direction (Y-axis direction in FIGS. 17 and 18) are equal. This makes it possible to suppress pulsation in the power received by power receiving coil 211.

[0107] The cores MM41 and MM42 of the second core unit are made of a magnetic material that induces the magnetic field generated by the coils L41 and L42 of the second coil unit, respectively. The cores MM41 and MM42 are typically made of ferrite.

[0108] Furthermore, the cores MM41 and MM42 of the second core section are integral with the coils L41 and L42 of the second coil section, and are arranged adjacent to each other at a distance in the horizontal direction (Y-axis direction). Here, to improve transmission efficiency, it is desirable that the second inter-core distance be approximately the same as the first inter-core distance.

[0109] The aluminum plate PL2 is disposed below the coils L41 and L42 and the cores MM41 and MM42 to reduce the influence of an external magnetic field on the power receiving circuit 210.

[0110] In the second embodiment of the present disclosure, a pair of coils are connected by connecting portions A5 and A6 provided on the opposing outer diameter sides as shown in Figures 17 and 18, which allows the wiring length at the connecting portions to be shorter than the connecting method in the first comparative example shown in Figures 7 and 8, thereby reducing the degree of imbalance in the X-direction magnetic field on the short side of the coil. However, since connecting portions A5 and A6 are located on the short side coil, some non-uniformity in the X-direction magnetic field occurs compared to the embodiment shown in Figures 1 to 5.

[0111] 4-2.Characteristics Fig. 19 is a diagram showing a comparison result of the far-field leakage magnetic field at a point 10 m away in the X direction shown in Fig. 10 between the contactless power transfer system of Comparative Example 1 (Figs. 7 and 8) and the contactless power transfer system 10 according to Embodiment 2 of the present disclosure (Figs. 17 and 18). As shown in Fig. 19, it can be seen that the contactless power transfer system 10 according to Embodiment 2 of the present disclosure (Figs. 17 and 18) is able to reduce the far-field leakage magnetic field by approximately 3 dB compared to the contactless power transfer system of Comparative Example 1 (Figs. 7 and 8).

[0112] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0113] 10. Contactless power transmission system 100 Power transmission device 110, 110A, 110B, 110C, 110D Power transmission circuit 111 Transmission coil 120 Immittance Filter 130 Inverter 140 AC / DC converter 200 Powered Device 210 Receiving circuit 211 Receiving coil 220 Immittance Filter 230 Rectifier circuit 300 power supply 400 battery A1, A2, A5, A6 joints AW1 First core distance AW2 Second core distance AG power transmission distance C24 smoothing capacitor L11, L12, L21, L22, L31, L32, L41, L42 coils MM11, MM12, MM21, MM22, MM31, MM32, MM41, MM42 core PL1, PL2 aluminum plates

Claims

1. A contactless power transfer system that transfers power from a power transmitting coil to a power receiving coil in a contactless manner, each of the power transmitting coil and the power receiving coil includes a pair of coil portions arranged adjacent to each other in a horizontal direction; Each of the coils of the coil unit is wound in a horizontal plane, and is configured so that the directions of magnetic fields generated by currents are opposite to each other, Each of the coils of the coil section has two long coil sides and two short coil sides, The connecting portions connecting the coils of the coil units are provided on the coil outer diameter sides of the adjacent coil long sides facing each other of the pair of coils, A contactless power transmission system in which the coils of a pair of coils are bent and wound so as to be approximately point-symmetrical with the approximate center of the connecting portion as the center of symmetry, so that the coil widths of the long sides of each coil are approximately equal.

2. each of the power transmitting coil and the power receiving coil includes a pair of core portions that induce a magnetic field generated by each of the coils of the coil portion; The contactless power transfer system according to claim 1 , wherein the core of each of the core sections is integral with the coil of each of the coil sections and is arranged at a distance from the core.

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