Coil group and non-contact power supply system

Abstract

To provide a coil group that can suppress fluctuation of power supply efficiency without increasing a physical build of power transmission coils in a height direction.SOLUTION: In a coil group, a plurality of primary coils are arranged in a plane form, and a maximum coupling coefficient sum kba, which is a coupling coefficient sum at a maximum position P2 (max) where a coupling coefficient sum which is a sum of a coupling coefficient of each of the primary coils of a primary coil group and a coupling coefficient of a secondary coil becomes maximum in a second position where a central axis of the secondary coil does not match a central axis of any of the plurality of primary coils, satisfies "D1<1 / 2×Max (ka, kba)" by using a first difference D1 between a first coupling coefficient ka and the maximum coupling coefficient sum kba, and a maximum value MAX (ka, kba) between the first coupling coefficient ka and the maximum coupling coefficient sum kba.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a coil group and a contactless power supply system. [Background technology]

[0002] Patent Document 1 discloses a technique in which charging coils for contactless power supply are arranged in a stacked manner, so that a vehicle pad for receiving power receives power from a plurality of charging coils. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2017-521984 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the charging coils are stacked, the height of the device increases. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] According to a first embodiment of the present disclosure, a coil group (GLA) is provided, comprising a plurality of primary coils (L1) and a secondary coil (L2) whose relative position with respect to the plurality of primary coils is changeable, the plurality of primary coils are arranged in a plane, the secondary coil is capable of contactlessly receiving power from at least one of the plurality of primary coils while changing the relative position, the secondary coil has a first position (P1) where a central axis (CX) of the secondary coil coincides with a central axis (CX) of one target primary coil among the plurality of primary coils, and a second position (P2) where a central axis of the secondary coil does not coincide with the central axis of any of the plurality of primary coils, and a second position at which the target primary coil can receive power from a primary coil group (GL) including at least two of the primary coils, and a first coupling coefficient ka between the target primary coil and the secondary coil at the first position, and a maximum coupling coefficient sum kba, which is the sum of the coupling coefficients between each primary coil of the primary coil group and the secondary coil at a maximum position (P2(max)) in the second position where the coupling coefficient sum is maximized, satisfy the following formula (1) using a first difference D1 between the first coupling coefficient ka and the maximum coupling coefficient sum kba and a maximum value MAX(ka, kba) between the first coupling coefficient ka and the maximum coupling coefficient sum kba. D1 < 1 / 2×Max(ka,kba) ···(1)

[0007] According to this embodiment, since the multiple power transmitting coils are arranged in a plane, the power receiving coil can receive power from the multiple power transmitting coils without increasing the height of the multiple primary coils. Furthermore, by satisfying formula (1), when the power receiving coil receives power while changing its position relative to the power transmitting coil, the fluctuation range of the power supply efficiency caused by the movement can be reduced.

[0008] According to a second embodiment of the present disclosure, a coil group (GLA) is provided, comprising a plurality of primary coils (L1) and a secondary coil (L2) whose relative position with respect to the plurality of primary coils is changeable, the plurality of primary coils are arranged in a plane, the secondary coil is capable of receiving power contactlessly from at least one of the plurality of primary coils while changing the relative position, and the secondary coil is movable between a first position (P1) where a central axis (CX) of the secondary coil coincides with a central axis (CX) of one target primary coil among the plurality of primary coils, and a second position (P2) where a central axis of the secondary coil does not coincide with the central axis of any of the plurality of primary coils, and the second position is capable of receiving power from a primary coil group (GL) including at least two of the plurality of primary coils. A specific coupling coefficient sum kbt, which is displaceable and is a coupling coefficient sum at a specific second position (P2(id)) at which (i) a first coupling coefficient ka between the target primary coil and the secondary coil at the first position, and (ii) a coupling coefficient sum which is the sum of the coupling coefficients between each primary coil of the primary coil group and the secondary coil at the second position coincide with each other, satisfies the following equation using a second difference D2 between the first coupling coefficient ka and the specific coupling coefficient sum kbt and a maximum value Max(ka, kba) between the first coupling coefficient ka and a maximum coupling coefficient sum kba which is a maximum value of the coupling coefficient sum. D2 < 1 / 2×Max(ka,kba) ···(6)

[0009] According to this embodiment, since the multiple transmitting coils are arranged in a plane, the receiving coil can receive power from the multiple transmitting coils without increasing the height of the multiple primary coils. Furthermore, by satisfying formula (6), when the receiving coil receives power while changing its position relative to the transmitting coil, the fluctuation range of the power supply efficiency caused by the movement can be reduced. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of a non-contact power supply system according to a first embodiment. [Diagram 2] FIG. 1 is a circuit diagram of a contactless power supply system according to a first embodiment. [Diagram 3] 4 is a flowchart of a power supply sequence. [Figure 4] 2A and 2B are diagrams illustrating the arrangement of a power transmitting coil and a power receiving coil according to the first embodiment. [Diagram 5] 11 is a diagram showing the relationship between the movement of a power receiving coil and a power transmitting coil that supplies power. [Figure 6] 1 is a flowchart of the design procedure. [Figure 7] A diagram explaining each step of the design procedure. [Figure 8] 10A and 10B are diagrams illustrating other arrangements of the power receiving coil and the power transmitting coil. [Figure 9] FIG. 11 is a circuit diagram of a non-contact power supply system according to a second embodiment. [Figure 10] FIG. 11 is a circuit diagram of a contactless power supply system according to a third embodiment. [Figure 11] FIG. 13 is a circuit diagram of a contactless power supply system according to a fourth embodiment. [Figure 12] FIG. 13 is a circuit diagram of a contactless power supply system according to a fifth embodiment. [Figure 13] FIG. 13 is a circuit diagram of a contactless power supply system according to a sixth embodiment. [Figure 14] 13A and 13B are diagrams illustrating other embodiments of the arrangement of power transmitting coils. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A. First embodiment: A1. Configuration of the wireless power supply system: As shown in FIG. 1, the contactless power supply system 1 includes a contactless power supply device 10 and a power receiving device 80. In this embodiment, the contactless power supply device 10 is buried under a road RS. The power receiving device 80 is mounted on a vehicle VE as a moving body that travels on the road RS. While the vehicle VE is traveling, the power receiving device 80 is supplied with power from the contactless power supply device 10. Here, traveling includes a case where the vehicle VE is moving and a case where the vehicle is stopped due to waiting for a traffic light or the like. The vehicle VE is configured as, for example, an electric vehicle or a hybrid vehicle. FIG. 1 shows an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other.

[0012] The non-contact power supply device 10 includes a power transmission unit 40 having a power transmission coil L1 as a primary coil, and an AC power source 11 that supplies power to the power transmission unit 40. The AC power source 11 supplies AC power of a predetermined operating frequency to the multiple power transmission units 40. The multiple power transmission coils L1 are arranged along the extension direction of the road RS and along a direction intersecting the extension direction. The extension direction of the road RS is the X-axis direction. The direction in which the power transmission coil L1 and the power receiving coil L2 face each other is the Z-axis direction. The power transmission coil L1 is arranged along the XY plane, as will be described in detail later.

[0013] The moving body on which the power receiving device 80 is mounted is not limited to a vehicle VE traveling on the road RS, and may be, for example, an AGV (automated guided vehicle), a traveling robot, etc. The power transmitting unit 40 may be installed not under the road RS, but on a sidewalk or parking lot adjacent to the road RS, or on a route along which the AGV travels.

[0014] The power receiving device 80 includes a battery 84 as a power storage device, a power receiving resonant circuit 81 having a power receiving coil L2 as a secondary coil, and a power receiving side control unit 96. The power receiving coil L2 can be magnetically coupled to the power transmitting coil L1. In this embodiment, the power receiving coil L2 is provided on the underside of the vehicle VE, facing the power transmitting coil L1.

[0015] The electric power received by the power receiving coil L2 is supplied to the battery 84. The battery 84 is a secondary battery that is charged by the supplied DC power. The electric power charged in the battery 84 is used as a driving force for traveling, etc.

[0016] The power receiving side control unit 96 controls each unit such as the power receiving resonant circuit 81 in the power receiving device 80. The power receiving side control unit 96 is realized by including an ECU (engine control unit). Note that the ECU may be realized by one microcontroller or may be realized by including multiple microcontrollers.

[0017] A2.Circuit configuration of the non-contact power supply system: As shown in FIG. 2, the power transmitting unit 40 has a power transmitting resonant circuit 42 and a switching circuit 44 in addition to the above configuration. The power transmitting resonant circuit 42 has a power transmitting coil L1, a power transmitting capacitor C1 as a primary capacitor, and a first switch SW1. The power transmitting capacitor C1 includes a first power transmitting capacitor C11 and a second power transmitting capacitor C12. The first switch SW1 is a bidirectional switch to which source terminals of two FETs (Field effect transistors) are connected. A switching signal Sig1 output from the switching circuit 44 is input to gate terminals of the two FETs. This controls the on / off state of the first switch SW1.

[0018] The first power transmitting capacitor C11 is connected in parallel with the power transmitting coil L1. The first switch SW1 is connected in series with the second power transmitting capacitor C12. The connection between the second power transmitting capacitor C12 and the first switch SW1 is connected in parallel with the power transmitting coil L1. The capacitance value of the power transmitting resonant circuit 42, which is a parallel resonant circuit, is switched by switching the on / off state of the first switch SW1.

[0019] The switching circuit 44 switches the state of the power transmitting resonant circuit 42 between a power supplying state in which power is supplied from the power transmitting coil L1 to the power receiving coil L2 and a non-power supplying state in which power is not supplied from the power transmitting coil L1 to the power receiving coil L2. In this embodiment, the switching circuit 44 switches the state of the power transmitting resonant circuit 42 between a resonant state and a non-resonant state by switching the first switch SW1 between an on state and an off state. As described later, when the power transmitting resonant circuit 42 is in a resonant state, power is supplied from the power transmitting coil L1 to the power receiving coil L2. When the power transmitting resonant circuit 42 is in a non-resonant state, power is not supplied from the power transmitting coil L1 to the power receiving coil L2. That is, the switching circuit 44 sets the power transmitting resonant circuit 42 to a power supplying state by setting the power transmitting resonant circuit 42 to a non-resonant state. The switching circuit 44 sets the power transmitting resonant circuit 42 to a non-power supplying state by setting the power transmitting resonant circuit 42 to a non-resonant state.

[0020] When the power transmitting resonant circuit 42 is set to a non-resonant state, the switching circuit 44 sets the first switch SW1 to an off state. When the power transmitting resonant circuit 42 is set to a non-resonant state, the switching circuit 44 sets the first switch SW1 to an on state. When the power transmitting coil L1 and the power receiving coil L2 are magnetically coupled, the capacitance value of the power transmitting capacitor C1, i.e., the combined capacitance of the first power transmitting capacitor C11 and the second power transmitting capacitor C12, is set to a value that causes the power transmitting resonant circuit 42 to be in a resonant state at the operating frequency. When the first switch SW1 is set to an off state, the resonant frequency of the power transmitting resonant circuit 42 deviates from the operating frequency, and the power transmitting resonant circuit 42 is in a non-resonant state.

[0021] The power receiving device 80 includes a power receiving resonant circuit 81, a rectifier circuit 83, and a battery 84. The power receiving resonant circuit 81 includes a power receiving coil L2 as a secondary coil, and a power receiving capacitor C2 as a secondary capacitor connected in series to the power receiving coil L2. The rectifier circuit 83 rectifies the AC power received by the power receiving resonant circuit 81, and supplies the rectified DC power to the battery 84.

[0022] When the power transmitting coil L1 and the power receiving coil L2 are magnetically coupled, the resonant frequency of the power transmitting resonant circuit 42 and the resonant frequency of the power receiving resonant circuit 81 are set to be substantially the same. This allows contactless power supply to the power receiving device 80 by magnetic field resonant coupling between the power transmitting coil L1 and the power receiving coil L2. As described above, the DC power output from the power receiving resonant circuit 81 is rectified by the rectifier circuit 83 and supplied to the battery 84.

[0023] In this embodiment, the primary side is a parallel resonant circuit, and the secondary side is a series resonant circuit, so that a so-called PS type non-contact power supply is performed. In this embodiment, the capacitance value of the power transmitting capacitor C1 is C1, the self-inductance of the power transmitting coil L1 is L1, the capacitance value of the power receiving capacitor C2 is C2, the self-inductance of the power receiving coil L2 is L2, and the angular frequency of the AC power output from the AC power source 11 is ω. The capacitance value C1 is set to satisfy the following formula (a1), and the capacitance value C2 is set to satisfy the following formula (a2). In this case, the secondary voltage V2 is ideally expressed by the following formula (a3) ​​using the primary voltage V1. C1=1 / (ω 2 L1) (a1) C2=1 / (ω 2 ·L2(1-k 2 )) (a2)

number

[0024] A3.Outline of power supply sequence: The position of the power receiving coil L2 relative to the multiple power transmitting coils L1 can be changed. The power transmitting coils L1 are arranged along the XY plane, and the power receiving coil L2 receives power from the nearest power transmitting coil L1 in a non-contact manner. The power transmitting unit 40 is set to either a standby state or a power supply state. Specifically, when the power transmitting unit 40 is set to the standby state, the switching circuit 44 sets the first switch SW1 to an off state and sets the power transmitting resonant circuit 42 to a non-resonant state. On the other hand, when the power transmitting unit 40 is set to the power supply state, the switching circuit 44 sets the first switch SW1 to an on state and sets the power transmitting resonant circuit 42 to a resonant state. The standby current flowing through the power transmitting coil L1 in the standby state is smaller than the power supply current flowing through the power transmitting coil L1 in the power supply state.

[0025] The power supply sequence will be described with reference to Fig. 3. The power transmission unit 40 is set to a standby state at the time of start-up.

[0026] In a standby state, the power transmission unit 40 causes a standby current to flow through the power transmission coil L1, thereby generating a magnetic flux from the power transmission coil L1. When the power receiving coil L2 approaches the power transmission coil L1, the power receiving device 80 detects the magnetic flux generated by the power transmission coil L1 using a secondary side detection circuit (not shown). When the power receiving device 80 detects the magnetic flux generated by the power transmission coil L1, it generates a starting magnetic flux. Specifically, the power receiving device 80 applies AC power to a magnetic flux generating coil (not shown). This causes the magnetic flux generating coil to generate a magnetic flux.

[0027] When the power transmitting unit 40 detects the magnetic flux generated by the power receiving device 80 with a magnetic sensor (not shown), it determines that the power receiving coil L2 is located near the power transmitting coil L1. When it determines in step S1 that the power receiving coil L2 is located near the power transmitting coil L1, it sets the power transmitting resonant circuit 42 to a resonant state in step S3. Specifically, the switching circuit 44 switches the first switch SW1 from an off state to an on state using a switching signal Sig1. This allows contactless power supply to the power receiving coil L2 by magnetic field resonant coupling between the power transmitting coil L1 and the power receiving coil L2.

[0028] When the power receiving coil L2 moves away from the power transmitting coil L1, the power transmitting unit 40 uses a magnetic sensor (not shown) to determine in step S5 that the power receiving coil L2 is not located near the power transmitting coil L1. When the switching circuit 44 determines in step S5 that the power receiving coil L2 is not located near the power transmitting coil L1, the switching circuit 44 sets the power transmitting resonant circuit 42 to a non-resonant state in step S7. Specifically, the switching circuit 44 switches the first switch SW1 from an on state to an off state using a switching signal Sig1. As a result, power supply is stopped and the power transmitting unit 40 is set to a standby state.

[0029] A4. Arrangement of the transmitting coil and the receiving coil: As shown in FIG. 4, the coil group GLA includes a plurality of power transmitting coils L1 and a power receiving coil L2. In this embodiment, the power transmitting coil L1 and the power receiving coil L2 are formed by winding a coil wire, which is a conductor coated with an insulating film, in a spiral or volute shape around a coil central axis CX, which is the central axis of the coil. As shown in the "side view" of FIG. 4, the power transmitting coil L1 and the power receiving coil L2 are arranged so that a coil plane Sc perpendicular to the coil central axis CX of the power transmitting coil L1 and a coil plane Sc of the power receiving coil L2 can face each other. Note that the power transmitting coil L1 and the power receiving coil L2 may be formed by stacking a plurality of printed circuit boards on which C-shaped printed wiring is formed, and conducting adjacent printed wiring in the Z-axis direction to form a spiral wiring.

[0030] As shown in the "plan view" of FIG. 4, the multiple power transmitting coils L1 are arranged in a planar shape. Here, "arranged in a planar shape" means that the multiple power transmitting coils L1 are arranged in a plurality of directions so that the coil planes Sc are along the same plane or the same curved surface and do not overlap with each other. "Arranged in a plurality of directions" means, specifically, that the power transmitting coils L1 are arranged not only in the X-axis direction but also in the Y-axis direction. In this embodiment, the power transmitting coils L1 are arranged at equal intervals. As described above, the power receiving coil L2 is mounted on the vehicle VE. The power receiving coil L2 can receive power contactlessly from at least one of the multiple power transmitting coils L1 while changing the relative position with respect to the power transmitting coil L1.

[0031] The reception of power by the moving power receiving coil L2 will be described with reference to Fig. 5. In Fig. 5, the hatched power transmitting coil L1 is a coil that is supplying power in a non-contact manner. Similarly, the hatched power receiving coil L2 is a coil that is receiving power. The power receiving coil L2 moves toward the right on the paper.

[0032] At "time t1" in FIG. 5, the receiving coil L2 approaches the power transmitting coil L1 in the array. As shown at "time t2" in FIG. 5, when the receiving coil L2 approaches the end power transmitting coil L1, contactless power transfer begins. At "time t3" in FIG. 5, the receiving coil L2 is also fed power from the end power transmitting coil L1. As shown at "time t4" in FIG. 5, when the vehicle travels and the distance between the power transmitting coil L1 next to the end power transmitting coil L1 and the receiving coil L2 becomes shorter, the receiving coil L2 also receives power from the power transmitting coil L1 next to the end power transmitting coil L1.

[0033] Here, as shown at "time t3" in FIG. 5, a position where the coil center axis CX of the receiving coil L2 coincides with the coil center axis CX of any one of the multiple power transmitting coils L1 is called a first position P1. At the first position P1, the power transmitting coil L1 whose coil center axis CX of the receiving coil L2 coincides with its own coil center axis CX is also called a target primary coil. As shown at "time t4", "time 5", and "time 6" in FIG. 5, a position where the coil center axis CX of the receiving coil L2 does not coincide with the coil center axis CX of any one of the multiple power transmitting coils L1 and where power can be received from the power transmitting coil group GL as a primary coil group including at least two power transmitting coils L1 among the multiple power transmitting coils L1 is called a second position P2. The receiving coil L2 is displaceable between the first position P1 and the second position P2.

[0034] In this embodiment, if the coupling coefficient k between the power transmitting coil L1 and the power receiving coil L2 at the first position P1 is defined as a first coupling coefficient ka, and the coupling coefficient sum kb at a maximum position P2(max) in the second position P2 where the coupling coefficient sum kb, which is the sum of the coupling coefficients k between each of the power transmitting coils L1 and the power receiving coil L2 of the power transmitting coil group GL, is maximized, is defined as a maximum coupling coefficient sum kba, the first coupling coefficient ka and the maximum coupling coefficient sum kba satisfy the following formula (1). As a result, as will be described in detail later, it is possible to suppress fluctuations in the coupling coefficient k that accompany movement. D1 < 1 / 2×Max(ka,kba) ···(1) In formula (1), "D1" is the difference between the first coupling coefficient ka and the maximum coupling coefficient sum kba. Also, in formula (1), "Max(ka, kba)" is the maximum value between the first coupling coefficient ka and the maximum coupling coefficient sum kba.

[0035] In the present embodiment, (i) a coupling coefficient k between each of the power transmitting coils L1 and the power receiving coil L2 in the power transmitting coil group GL at the second position P2, A specific coupling coefficient sum kbt, which is a coupling coefficient sum kb at a specific second position P2(id) where at least one of the coupling coefficients k corresponding to the power transmitting coil L1 coincides with (ii) the coupling coefficient sum kb which is the sum of the coupling coefficients k between each of the power transmitting coils L1 and the power receiving coil L2 in the power transmitting coil group GL, satisfies the following formula (6). As a result, as will be described in detail later, it is possible to suppress fluctuations in the coupling coefficient k that accompany movement. D2 < 1 / 2×Max(ka,kba) ···(6) In equation (6), "D2" is the difference between the first coupling coefficient ka and the specific coupling coefficient sum kbt.

[0036] Specifically, in the non-contact power supply system 1, the sizes of the power transmitting coil L1 and the power receiving coil L2, the distance between the power transmitting coils L1, and the heightwise distance between the power transmitting coil L1 and the power receiving coil L2 are set so as to satisfy the above formulas (1) and (6).

[0037] The size of the power transmitting coil L1 and the power receiving coil L2 is, in detail, the outer diameter of each coil. In this specification, as shown in FIG. 4, the size of the power transmitting coil L1 and the power receiving coil L2 is expressed by the smallest rectangle that contains and contacts each coil. The maximum outer diameter of the coil is the length of the long side of the smallest rectangle that contains and contacts the coil. The minimum outer diameter of the coil is the length of the short side of the smallest rectangle that contains and contacts the coil. The smallest rectangle that contains and contacts the coil is parallel to the coil plane Sc. When the smallest rectangle that contains and contacts the coil is a square, the maximum outer diameter of the coil coincides with the minimum outer diameter. In this specification, when the maximum outer diameter and the minimum outer diameter of the coil coincide, the maximum outer diameter is used to express the size of the coil. In this embodiment, the shape of the power transmitting coil L1 and the power receiving coil L2 projected onto the coil plane is approximately a square. In other words, the smallest rectangle that contains and contacts the coil is a square.

[0038] 4, the maximum outer diameter Drmax of the receiving coil L2 is larger than the maximum outer diameter Dsmax of the transmitting coil L1. The coil spacing Gs of the transmitting coil L1 in the XY plane and the coil gap Gz, which is the minimum distance in the Z direction between the coil plane Sc of the transmitting coil L1 and the coil plane Sc of the receiving coil L2, are set to values ​​that satisfy the above formulas (1) and (6).

[0039] A5. Design procedure for transmit coil and receive coil: A design procedure for determining each parameter of the power transmitting coil L1 and the power receiving coil L2 of the contactless power supply device 10 so as to satisfy the above formulas (1) and (6) will be described with reference to Fig. 6. Specifically, the parameters include the self-inductance of the power transmitting coil L1, the self-inductance of the power receiving coil L2, the maximum outer diameter Dsmax and the minimum outer diameter Dsmin of the power transmitting coil L1, the maximum outer diameter Drmax and the minimum outer diameter Drmin of the power receiving coil L2, the coil interval Gs, and the inter-coil gap Gz.

[0040] For ease of understanding, as shown in the "plan view" of Fig. 7, four power transmitting coils L1 are arranged, and the power receiving coil L2 moves in the X direction along a straight line connecting the coil central axes CX of the power transmitting coils L1 in a plan view along the Z axis direction. In the following description, the power transmitting coils L1 are numbered "(n)" to distinguish each of the four power transmitting coils L1. The two power transmitting coils L1 located on the movement path of the power receiving coil L2 are numbered "(1)" and "(2)" in order from upstream to downstream in the movement direction.

[0041] In step S1 of Fig. 6, the designer sets the values ​​of each parameter. In step S3, the mutual inductance M and the self-inductance L at each position are acquired. The inductances can be acquired by simulation or by actual measurement. By repeating the process of setting the position of the receiving coil L2 and acquiring each inductance, each inductance for the X position, which is the position in the X-axis direction, can be acquired.

[0042] As shown in “S3” in FIG. 7, for example, the mutual inductance M between the power transmitting coil L1 and the power receiving coil L2 is 21 is maximum at a first position P1 where the coil central axis CX of the power transmitting coil L1 and the coil central axis CX of the power receiving coil L2 coincide in a plan view. Specifically, the mutual inductance M between the power transmitting coil L1(1) and the power receiving coil L2, 21 (1) is maximum at a first position P1(1) where the coil central axis CX of the power transmitting coil L1(1) and the coil central axis CX of the power receiving coil L2 coincide in a plan view. Similarly, the mutual inductance M 21 is the mutual inductance M 21 (2) is maximum at a first position P1(2) where the coil central axis CX of the power transmitting coil L1(2) and the coil central axis CX of the power receiving coil L2 coincide in a plan view. Note that since there are a plurality of first positions P1 corresponding to the arrangement in which a plurality of power transmitting coils L1 are arranged, the first positions P1 are distinguished by the same notation as the power transmitting coil L1, that is, by adding the number "(n)" to the first positions P1, as described above.

[0043] In addition, in "S3" of FIG. 7, the self-inductance L is omitted. In addition, in reality, the mutual inductance M 21 (1) and the mutual inductance M 21 In addition to (2), the mutual inductance M 21 (3) and the mutual inductance M 21 (4) is obtained. However, for ease of understanding, in the following description, the mutual inductance M 21 (3) and the mutual inductance M 21 (4) is the mutual inductance M 21 (1) and the mutual inductance M 21 Regarding (2), we will explain this by assuming that it is small enough to be ignored.

[0044] 6, the designer calculates the coupling coefficient k at each position. The coupling coefficient k is expressed by the following formula (b1) using the mutual inductance M, the self-inductance L1 of the power transmitting coil L1, and the self-inductance L2 of the power receiving coil L2.

number

[0045] In step S7, the designer calculates the coupling coefficient sum kb at each position. The sum of the coupling coefficients k calculated for each position in step S5 is the coupling coefficient sum kb. In the illustrated example, the coupling coefficient sum kb is calculated by adding the coupling coefficient k(1) and the coupling coefficient k(2).

[0046] In step S9, the designer obtains the maximum value of the coupling coefficient k and the coupling coefficient sum kb at each position. Specifically, the maximum value of the coupling coefficient k(1), the coupling coefficient k(2), and the coupling coefficient sum kb is obtained at each position. In the case of the illustrated arrangement, as shown in FIG. 7, the characteristic line CL, which is a curve drawn by the maximum values ​​of the coupling coefficient k and the coupling coefficient sum kb at each position, has three maximum points. In this embodiment, the power transmitting coils L1 are all the same size and are arranged in a matrix shape at equal intervals, so that the characteristic line CL has a maximum value at the midpoint between the coil central axis CX of the power transmitting coil L1(1) and the coil central axis CX of the power transmitting coil L1(2) in a plan view. In other words, the midpoint between the coil central axis CX of the power transmitting coil L1(2) and the maximum position P2(max) coincides with each other.

[0047] That is, the characteristic line CL has maxima at the first position P1(1), the first position P1(2), and the maximum position P2(max). As described above, the first position P1(1) and the first position P1(2) are positions where the coil central axis CX of the power transmitting coil L1(1) and the coil central axis CX of the power transmitting coil L1(2) coincide with each other. The maximum position P2(max) is an intermediate position between the coil central axis CX of the power transmitting coil L1(1) and the coil central axis CX of the power transmitting coil L1(2). When the power transmitting coils L1 of the same size are arranged on the same plane at equal intervals, the center of gravity of the coil central axis CX of each power transmitting coil L1 of the power transmitting coil group GL becomes the maximum position P2(max) in a planar view.

[0048] The maximum position P2(max) is the position of a maximum point that appears on the characteristic line CL in the process of moving the receiving coil L2 from a position where the coil center axis CX of the target transmitting coil and the coil center axis CX of the receiving coil L2 coincide to a position where the coil center axis CX of the transmitting coil L1 adjacent to the target transmitting coil and the coil center axis CX of the receiving coil L2 coincide, that is, in the section from the first position P1 to the next first position P1.

[0049] Here, the coupling coefficient k at the first position P1 is called a first coupling coefficient ka, and the coupling coefficient sum kb at the maximum position P2(max) is called a maximum coupling coefficient sum kba.

[0050] 6, the designer determines whether the first difference D1 is smaller than the first target difference Dtg1. Here, the first difference D1 is expressed by the formula (b2). D1 = |ka-kba| (b2) The first target difference Dtg1 is set to a value that is at least half or less than the maximum value MAX(ka, kba), which is the larger value of the first coupling coefficient ka or the maximum coupling coefficient sum kba. In the illustrated example, as shown in "S11" in Fig. 7, the maximum coupling coefficient sum kba is greater than the first coupling coefficient ka, so "kba / 2" is set to the first target difference Dtg1. Unlike this embodiment, the first target difference Dtg1 may be set to a value smaller than "kba / 2".

[0051] The power receiving coil L2 receives power while changing its position relative to the power transmitting coil L1. When the positional relationship between the power transmitting coil L1 and the power receiving coil L2 changes, the inductances of the coils change, and the power supply efficiency also changes. Reducing the fluctuation range of the inductance associated with the displacement reduces the fluctuation range of the power supply efficiency, which is preferable because it makes it possible to stabilize the power supply to the battery 84. In other words, the smaller the first difference D1, the more stable the power supply to the battery 84, which is preferable.

[0052] 6, if it is determined that the first difference D1 is not smaller than the first target difference Dtg1, then in step S15, the designer changes the value of at least one parameter among the multiple parameters set in step S1. After changing the parameters in step S15, the designer performs step S3 using the changed parameters.

[0053] 5, when it is determined that the first difference D1 is smaller than the first target difference Dtg1, the designer determines in step S13 whether the second difference D2 is smaller than the second target difference Dtg2. Here, the second difference D2 is expressed by the formula (b3). D2 = |kb-kbt| (b3) As described above, "kb" in formula (b3) is the sum of the coupling coefficients k between each of the power transmitting coils L1 and the power receiving coil L2 in the power transmitting coil group GL. "kbt" in formula (b3) is the specific coupling coefficient sum kbt, which is the coupling coefficient sum kb at the specific second position P2(id) where at least one coupling coefficient k and the coupling coefficient sum kb match. In the illustrated example, as shown in "S13" in Fig. 7, the coupling coefficient sum kb is the sum of the coupling coefficient k(1) and the coupling coefficient k(2), so the position where the coupling coefficient k(2) is zero is the specific second position P2(id).

[0054] The second target difference Dtg2 is set in the same manner as the first target difference Dtg1. That is, the second target difference Dtg2 is set to a value equal to or less than half the maximum value MAX(ka, kba), which is the larger value of the first coupling coefficient ka and the maximum coupling coefficient sum kba. In the illustrated example, since the maximum coupling coefficient sum kba is larger than the first coupling coefficient ka, a value equal to or less than "kba / 2" is set to the second target difference Dtg2. In this embodiment, the second target difference Dtg2 is set to the same value as the first target difference Dtg1. Unlike this embodiment, the second target difference Dtg2 may be set to a value smaller than "kba / 2". In addition, the second target difference Dtg2 may be set to a value different from the first target difference Dtg1.

[0055] As with the first difference D1, the smaller the second difference D2 is, the more stable the power supply to the battery 84 can be, which is preferable.

[0056] If it is determined in step S13 that the second difference D2 is not smaller than the second target difference Dtg2, the designer proceeds to step S15. On the other hand, if it is determined in step S13 that the second difference D2 is smaller than the second target difference Dtg2, the fluctuation range of the power supply efficiency associated with the displacement of the power receiving coil L2 can be kept below the target value, and the designer ends the design.

[0057] The design method described above can be realized by using a computer. Specifically, steps S1, S3, and S15 are obtained by accepting values ​​input by a designer, and the design method can be realized by having a computer execute a program that realizes the design method.

[0058] A6. Power supply sequence details: As described with reference to Fig. 3, the switching circuit 44 sets the power transmitting resonant circuit 42 to a resonant state and starts power supply in step S3 in Fig. 3. Then, the switching circuit 44 sets the power transmitting resonant circuit 42 to a non-resonant state and stops power supply in step S7 in Fig. 3. Also, as described with reference to Fig. 4, the arranged power transmitting coils L1 are switched in sequence from a standby state to a power supply state in accordance with the movement of the power receiving coil L2.

[0059] When the switching circuit 44 determines that the power receiving coil L2 is located at the specific second position P2(id), it switches the power transmitting resonant circuit 42 between a non-power supply state and a power supply state. Explained with reference to FIG. 5, the switching circuit 44 of the power transmitting coil L1(2) switches the power transmitting resonant circuit 42 from a non-power supply state to a power supply state at "time t4" when the power receiving coil L2 is located at the specific second position P2(id). This allows the non-contact power supply device 10 to supply power efficiently. Even if the power supply state is switched to a power supply state from a time before "time t4", effective power supply cannot be performed because the mutual inductance M is small. Therefore, when it is determined that the power receiving coil L2 is located at the specific second position P2(id), the power transmitting resonant circuit 42 is switched from a non-power supply state to a power supply state, thereby allowing efficient power supply.

[0060] Similarly, the switching circuit 44 of the power transmitting coil L1(1) switches the power transmitting resonant circuit 42 from the power supplying state to the power non-supplying state at "time t6" when the power receiving coil L2 is located at the specific second position P2(id).

[0061] A7. Other forms of arrangement of the transmitting coil and the receiving coil: In the above, a case where four power transmitting coils L1 are arranged has been described with reference to Fig. 7. The number of power transmitting coils L1 is not limited to four. For example, as shown in Fig. 8, even in a case where three or more power transmitting coils L1 are arranged in the X direction, the specific second position P2(id) can be obtained in the same manner as described above.

[0062] In the case of the contactless power transfer system 1 that satisfies the above formulas (1) and (6), the fluctuation range of the power transfer efficiency caused by the movement of the power receiving coil L2 can be suppressed regardless of the movement path of the power receiving coil L2. That is, as described above, not only when the power receiving coil L2 moves along the straight line connecting the coil central axis CX of the power transmitting coil L1, but also when the power receiving coil L2 moves in a direction intersecting with the X-axis direction in which the power receiving coil L2 is arranged, as shown by the arrow DA in Fig. 8, the fluctuation range of the power transfer efficiency caused by the movement of the power receiving coil L2 can be suppressed. That is, by satisfying formulas (1) and (6), it is possible to provide a contactless power transfer system 1 that suppresses fluctuations in the supply current to the battery 84 regardless of the movement path of the power receiving coil L2.

[0063] According to the first embodiment described above, the multiple power transmitting coils L1 are arranged in a planar shape. Therefore, the power receiving coil L2 can receive power from the multiple power transmitting coils L1 without increasing the height size of the coil group GLA. Furthermore, the first difference D1 between the first coupling coefficient ka and the maximum coupling coefficient sum kba, and the maximum value MAX(ka, kba) between the first coupling coefficient ka and the maximum coupling coefficient sum kba satisfy the formula (1). Therefore, when the power receiving coil L2 receives power while changing its relative position with the power transmitting coil L1, the fluctuation range of the power supply efficiency caused by the movement can be reduced.

[0064] The power transmitting resonant circuit 42 and the power receiving resonant circuit 81 are configured so that a coupling coefficient k between the power transmitting coil L1 and the power receiving coil L2 has a positive correlation with the power output to the battery 84. As a result, the larger the coupling coefficient k, the larger the power that can be supplied to the battery 84. The non-contact power supply system 1 is a so-called PS type non-contact power supply system in which the power transmitting resonant circuit 42 is a parallel resonant circuit and the power receiving resonant circuit 81 is a series resonant circuit. As a result, a configuration can be realized in which the coupling coefficient k and the power output to the battery 84 have a positive correlation.

[0065] In addition, the maximum outer diameter Dsmax of the transmitting coil L1, the minimum outer diameter Dsmin of the transmitting coil L1, the maximum outer diameter Drmax of the receiving coil L2, and the minimum outer diameter Drmin of the receiving coil L2 are the same, and since the maximum outer diameter Drmax and the minimum outer diameter Drmin are the same, both of the following equations (2) and (3) are satisfied. Drmax > Dsmax ···(2) Drmin > Dsmin ···(3) As a result, at the second position P2, the power receiving coil L2 can easily receive power from the multiple power transmitting coils L1, thereby realizing the contactless power transfer system 1 that satisfies the above formulas (1) and (6). Note that it is preferable that the maximum outer diameter Drmax is about twice the maximum outer diameter Dsmax, and the minimum outer diameter Drmin is about twice the minimum outer diameter Dsmin.

[0066] Furthermore, the second difference D2 between the first coupling coefficient ka and the specific coupling coefficient sum kbt, and the maximum value Max(ka, kba) between the first coupling coefficient ka and the maximum coupling coefficient sum kba, which is the maximum value of the coupling coefficient sum kb, satisfy the formula (6). Therefore, when the power receiving coil L2 receives power while changing its position relative to the power transmitting coil L1, the fluctuation range of the power supply efficiency caused by the movement can be reduced.

[0067] B. Second embodiment: A power transmitting resonant circuit 242 included in a power transmitting unit 240 according to this embodiment has a circuit configuration different from that of the power transmitting resonant circuit 42 of the first embodiment. The same components as those in the above embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0068] As shown in FIG. 9, the power transmitting capacitor C1 of the power transmitting resonant circuit 242 includes a first parallel primary capacitor C1p1 and a second parallel primary capacitor C1p2 as parallel primary capacitors, and a series primary capacitor C1s. The first switch SW1 is connected in series with the second parallel primary capacitor C1p2. A connection between the second parallel primary capacitor C1p2 and the first switch SW1 is connected in parallel with the power transmitting coil L1. The second parallel primary capacitor C1p2 is connected in parallel with the power transmitting coil L1. The series primary capacitor C1s is connected in series with the power transmitting coil L1. The capacitance values ​​of the first parallel primary capacitor C1p1, the second parallel primary capacitor C1p2, and the series primary capacitor C1s are set to values ​​that are in a resonant state at the operating frequency when the first switch SW1 is set to an on state. The power transmitting resonant circuit 242 and the power receiving resonant circuit 81 perform a so-called PS-S type non-contact power supply.

[0069] In the power transmitting resonant circuit 242, similarly to the PS system, there is a positive correlation between the coupling coefficient k between the power transmitting coil L1 and the power receiving coil L2 and the secondary voltage V2. Therefore, there is a positive correlation between the coupling coefficient k and the power output to the battery 84.

[0070] According to the second embodiment described above, the same effects as those of the above embodiment are achieved.

[0071] C. Third embodiment: 10 differs from the above-described embodiments in that it has a coupling circuit 346 and in the circuit configuration of the power transmitting resonant circuit 342. The same components as those in the above-described embodiments are denoted by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0072] The power transmitting unit 340 has a coupling circuit 346. The coupling circuit 346 is used to establish or cut off a power transmission path between the power transmitting unit 340 and the power receiving device 80. The coupling circuit 346 has a tertiary coil L3 and a tertiary capacitor C3. The tertiary capacitor C3 is connected in parallel to the tertiary coil L3. The tertiary coil L3 is disposed at a position where it can be magnetically coupled to the power transmitting coil L1. As a result, when the power transmitting coil L1 and the power receiving coil L2 are magnetically coupled to each other, the power transmitting coil L1, the power receiving coil L2, and the tertiary coil L3 are magnetically coupled to each other.

[0073] The first power transmitting capacitor C11 is connected in series with the power transmitting coil L1. The second power transmitting capacitor C12 is connected in series with the first switch SW1. A connection between the second power transmitting capacitor C12 and the first switch SW1 is connected in parallel with the first power transmitting capacitor C11. The first switch SW1 is set to an on state when the power transmitting resonant circuit 342 is set to a resonant state. The combined capacitance of the first power transmitting capacitor C11 and the second power transmitting capacitor C12 is set to a value that puts the power transmitting resonant circuit 342 into a resonant state at the operating frequency.

[0074] The capacitance value of the tertiary capacitor C3 is set to a value that causes the parallel resonant circuit formed by the tertiary coil L3 and the tertiary capacitor C3 to enter a resonant state when the transmitting coil L1, the receiving coil L2, and the tertiary coil L3 are magnetically coupled to each other.

[0075] The switching circuit 44 switches the power transmitting resonant circuit 342 from a non-resonant state to a resonant state, and switches the power transmitting unit 340 from a standby state to a power supplying state. Specifically, the switching circuit 44 switches the first switch SW1 from an off state to an on state, as described above. This causes a power supply current to flow through the power transmitting coil L1 and the tertiary coil L3 magnetically coupled to the power transmitting coil L1, and power is supplied contactlessly to the power receiving coil L2.

[0076] In response, the switching circuit 44 switches the power transmitting resonant circuit 342 from a resonant state to a non-resonant state, and switches the power transmitting unit 340 from a power feeding state to a standby state. Specifically, the switching circuit 44 switches the first switch SW1 from an on state to an off state, as described above. This switches the power transmitting unit 340 to a standby state in which a standby current smaller than the power feeding current flows through the power transmitting coil L1.

[0077] Most of the power that the power receiving resonant circuit 81 receives from the power transmitting unit 340 is due to the magnetic coupling between the power receiving coil L2 and the tertiary coil L3. Therefore, the larger the coupling coefficient k between the tertiary coil L3 and the power receiving coil L2, the larger the current value of the current I2 flowing through the power receiving coil L2. In the first embodiment, the sizes of the power transmitting coil L1 and the power receiving coil L2, the interval between the power transmitting coil L1, and the heightwise distance between the power transmitting coil L1 and the power receiving coil L2 are set to satisfy the above formulas (1) and (6). In contrast, in this embodiment, the sizes of the tertiary coil L3 and the power receiving coil L2, the interval between the tertiary coil L3, and the heightwise distance between the tertiary coil L3 and the power receiving coil L2 are set to satisfy the above formulas (1) and (6). That is, in this embodiment, the tertiary coil L3 is arranged in the same manner as the power transmitting coil L1 shown in FIG. 8.

[0078] In this embodiment, the capacitance value of the power transmitting capacitor C1 is C1, the self-inductance of the power transmitting coil L1 is L1, the capacitance value of the power receiving capacitor C2 is C2, the self-inductance of the power receiving coil L2 is L2, the capacitance value of the tertiary capacitor C3 is C3, the self-inductance of the tertiary coil L3 is L3, and the coupling coefficient between the power transmitting coil L1 and the power receiving coil L2 is k 12 , the coupling coefficient between the transmitting coil L1 and the tertiary coil L3 is k 13 , the coupling coefficient between the receiving coil L2 and the tertiary coil L3 is k 32 The capacitance value C1 is set to satisfy the formula (c1), the capacitance value C2 is set to satisfy the formula (c2), and the capacitance value C3 is set to satisfy the formula (c3), where ω is the angular frequency of the AC power output from the AC power supply 11. In this case, the secondary voltage V2 is ideally expressed by the formula (c4). C1=1 / (ω 2 L1) (c1) C2=1 / (ω 2 ·L2(1-(2·k 32 k 12 ) / k 13 )) ···(c2) C3=1 / (ω 2 L3) (c3)

number

[0079] According to the third embodiment described above, the same effects as those of the above embodiments are achieved.

[0080] D. Fourth embodiment: 11, the circuit configuration of a power transmitting unit 440 according to this embodiment is different from that of the third embodiment. The same components as those in the above embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.

[0081] In this embodiment, the coupling circuit 346 of the third embodiment is connected to the power transmitting resonant circuit 442. Specifically, the tertiary coil L3 is connected in series with the power transmitting coil L1. The tertiary capacitor C3 is connected in parallel with the tertiary coil L3.

[0082] In this embodiment, as in the third embodiment, the capacitance value of the tertiary capacitor C3 is set to a value that causes a parallel resonant circuit formed by the tertiary coil L3 and the tertiary capacitor C3 to resonate when the power transmission coil L1, the power reception coil L2, and the tertiary coil L3 are magnetically coupled to each other. Most of the power that the power reception resonant circuit 81 receives from the power transmission unit 440 is due to the magnetic coupling between the power reception coil L2 and the tertiary coil L3. Therefore, the current value of the current I2 flowing through the power reception coil L2 increases as the coupling coefficient k between the tertiary coil L3 and the power reception coil L2 increases. In addition, the sizes of the tertiary coil L3 and the power reception coil L2, the interval between the tertiary coil L3, and the height direction distance between the tertiary coil L3 and the power reception coil L2 are set to satisfy the above formula (1) and formula (6).

[0083] In the power transmitting resonant circuit 442 as well, there is a positive correlation between the coupling coefficient k between the power transmitting coil L1 and the power receiving coil L2 and the secondary voltage V2.

[0084] According to the fourth embodiment described above, the same effects as those of the above embodiments are achieved.

[0085] E. Fifth embodiment: 12, the power transmitting unit 540 according to this embodiment differs from each of the above-described embodiments in the circuit configuration of the power transmitting resonant circuit 542. The same components as those in each of the above-described embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.

[0086] The first power transmitting capacitor C11 is connected in series with the power transmitting coil L1. The second power transmitting capacitor C12 is connected in series with the first switch SW1. A connection between the second power transmitting capacitor C12 and the first switch SW1 is connected in parallel with the first power transmitting capacitor C11. The first switch SW1 is set to an on state when the power transmitting resonant circuit 542 is set to a resonant state. The combined capacitance of the first power transmitting capacitor C11 and the second power transmitting capacitor C12 is set to a value that sets the power transmitting resonant circuit 542 to a resonant state at the operating frequency. The power transmitting resonant circuit 542 and the power receiving resonant circuit 81 perform a so-called SS type non-contact power supply.

[0087] Furthermore, if the self-inductance of the transmitting coil L1 is L1, the capacitance of the transmitting capacitor C1, i.e., the combined capacitance of the first transmitting capacitor C11 and the second transmitting capacitor C12, is C1, the self-inductance of the receiving coil L2 is L2, the capacitance of the receiving capacitor C2 is C2, the coupling coefficient between the transmitting coil L1 and the receiving coil L2 is k, and the angular frequency of the AC power of the AC power supply 11 is ω, then the capacitance value C1 satisfies the following equation (4), and the capacitance value C2 satisfies the following equation (5). C1=1 / (ω 2 ×L1×(1+k)) (4) C2=1 / (ω 2 ×L2×(1+k)) (5) As a result, the coupling coefficient k between the power transmitting coil L1 and the power receiving coil L2 and the power output from the power receiving resonant circuit 81 to the battery 84 have a positive correlation.

[0088] According to the fifth embodiment described above, the same effects as those of the above embodiments are achieved.

[0089] F. Sixth embodiment: 13, the power transmitting unit 640 according to this embodiment differs from each of the above-described embodiments in the circuit configuration of the power transmitting resonant circuit 642. The same components as those in each of the above-described embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.

[0090] The power transmitting resonant circuit 642 has a changeover switch SWs that switches whether or not the AC power supplied from the AC power source 11 is supplied to the power transmitting coil L1. The changeover switch SWs is realized by, for example, a semiconductor switch. The changeover circuit 44 controls the changeover switch SWs. The power transmitting capacitor C1 is connected in parallel to the power transmitting coil L1.

[0091] At the specific second position P2(id) ("S13" in FIG. 7), the switching circuit 44 switches the state of the changeover switch SWs between an ON state as a supply state in which AC power is supplied to the power transmitting coil L1 and an OFF state as a stop state in which AC power is not supplied to the power transmitting coil L1. That is, the switching circuit 44 sets the changeover switch SWs to the ON state and sets the power transmitting resonant circuit 642 to a power supply state. The switching circuit 44 sets the changeover switch SWs to the OFF state and sets the power transmitting resonant circuit 642 to a non-power supply state. This allows efficient power supply.

[0092] According to the sixth embodiment described above, the same effects as those of the above embodiments are achieved.

[0093] G. Other embodiments: (G1) In the first embodiment, the shape of the power transmitting coil L1 and the power receiving coil L2 projected onto the coil plane Sc is substantially square. The shape of the power transmitting coil L1 and the power receiving coil L2 may be other shapes. Specifically, the shape of the power transmitting coil L1 projected onto the coil plane Sc may be circular, rectangular, or other polygonal. In the first embodiment, the power transmitting coils L1 are arranged at equal intervals with a coil interval Gs. The arrangement of the multiple power transmitting coils L1 is not limited to this. For example, as shown in "Other Form 1" in FIG. 14, the multiple power transmitting coils L1 may be arranged without a coil interval Gs. Also, as shown in "Other Form 2", the multiple power transmitting coils L1 may be arranged such that a straight line SL1 connecting the coil central axes CX of the multiple power transmitting coils L1 arranged in the Y-axis direction and a straight line SL2 connecting the coil central axes CX of the multiple power transmitting coils L1 arranged in the X-axis direction are not perpendicular to each other. Also, the multiple power transmitting coils L1 may be arranged irregularly. The same applies to the tertiary coil L3 in the third and fourth embodiments.

[0094] (G2) In the first embodiment, the switching element constituting the first switch SW1 is realized by a FET. In another embodiment, the switching element may be realized by another semiconductor element, for example, an IGBT (Insulated Gate Bipolar Transistor) connected to a freewheeling diode. In addition, the first switch SW1 is not limited to a bidirectional switch, and may be a unidirectional switch composed of one switching element.

[0095] The present disclosure is not limited to the above-mentioned embodiments and modifications, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments and modifications corresponding to the technical features in each aspect described in the Summary of the Invention column can be appropriately replaced or combined in order to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0096] H. Other forms: The features of the present disclosure are as follows: (Form 1) A coil group (GLA), A plurality of primary coils (L1); A secondary coil (L2) whose relative position with respect to the plurality of primary coils is changeable, The plurality of primary coils are arranged in a plane, the secondary coil is capable of receiving power in a non-contact manner from at least one of the plurality of primary coils while changing the relative position; The secondary coil is a first position (P1) where a central axis (CX) of the secondary coil coincides with a central axis (CX) of one target primary coil among the plurality of primary coils; a second position (P2) in which a central axis of the secondary coil does not coincide with a central axis of any of the plurality of primary coils, and in which power can be received from a primary coil group (GL) including at least two of the plurality of primary coils; a first coupling coefficient ka between the target primary coil and the secondary coil at the first position; a maximum coupling coefficient sum kba at a maximum position (P2(max)) where the sum of the coupling coefficients between the primary coils of the primary coil group and the secondary coil is maximized among the second positions is A coil group that satisfies the following formula (1) using a first difference D1 between the first coupling coefficient ka and the maximum coupling coefficient sum kba, and a maximum value MAX(ka, kba) between the first coupling coefficient ka and the maximum coupling coefficient sum kba. D1 < 1 / 2×Max(ka,kba) ···(1) (Form 2) A non-contact power supply system (1) including the coil group according to aspect 1, A plurality of power transmitting resonant circuits (42, 242 to 642) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the power transmitting resonant circuits includes a primary coil of each of the primary coils and a primary capacitor (C1); A contactless power supply system in which each of the multiple power transmitting resonant circuits and the power receiving resonant circuit are configured so that a coupling coefficient between the primary coil and the secondary coil has a positive correlation with the power output to the power storage device. (Form 3) 3. The coil group according to claim 1 or 2, A coil group that satisfies at least one of the following formula (2) and formula (3), where the maximum outer diameter of the primary coil is Dsmax, the minimum outer diameter of the primary coil is Dsmin, the maximum outer diameter of the secondary coil is Drmax, and the minimum outer diameter of the secondary coil is Drmin. Drmax > Dsmax ···(2) Drmin > Dsmin ···(3) (Form 4) The wireless power supply system according to aspect 2 or 3, Each of the plurality of power transmitting resonant circuits is a parallel resonant circuit in which the primary capacitor is connected in parallel to the primary coil, The power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil. (Form 5) The wireless power supply system according to aspect 2 or 3, The primary capacitor includes a parallel primary capacitor (C1p1, C1p2) connected in parallel with the primary coil, and a series primary capacitor (C1s) connected in series with the primary coil, Each of the plurality of power transmitting resonant circuits is a resonant circuit configured with the primary coil, the parallel primary capacitor, and the series primary capacitor, The power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil. (Form 6) A non-contact power supply system (1) including the coil group according to aspect 1, A plurality of power transmitting resonant circuits (342) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the plurality of power transmitting resonant circuits includes: (i) a series resonant circuit having a primary coil of each of the plurality of primary coils and a capacitor (C1) connected in series with the primary coil; and (ii) a coupling circuit (346) having a tertiary coil (L3) capable of magnetically coupling with the primary coil and a tertiary capacitor (C3) connected in parallel with the tertiary coil; the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil, A contactless power supply system in which each of the multiple power transmitting resonant circuits and the power receiving resonant circuit are configured so that a coupling coefficient between the tertiary coil and the secondary coil has a positive correlation with the power output to the power storage device. (Form 7) A non-contact power supply system (1) including the coil group according to aspect 1, A plurality of power transmitting resonant circuits (442) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the power transmitting resonant circuits of the plurality of power transmitting resonant circuits includes a primary coil of each of the plurality of primary coils, a primary capacitor (C1) connected in series to the primary coil, and a tertiary coil (L3) capable of magnetic coupling with the primary coil, the tertiary coil being connected in series with the primary coil, and a tertiary capacitor (C3) connected in parallel with the tertiary coil; and the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series to the secondary coil, A contactless power supply system in which each of the multiple power transmitting resonant circuits and the power receiving resonant circuit are configured so that a coupling coefficient between the tertiary coil and the secondary coil has a positive correlation with the power output to the power storage device. (Form 8) The wireless power supply system according to aspect 2 or 3, The power supply further includes an AC power source (11) that supplies AC power having a predetermined operating frequency to the plurality of power transmitting resonant circuits, Each of the plurality of power transmitting resonant circuits is a series resonant circuit in which the primary capacitor is connected in series to the primary coil, the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil, A contactless power supply system in which, when the self-inductance of the primary coil is L1, the capacitance value of the primary capacitor is C1, the self-inductance of the secondary coil is L2, the capacitance value of the secondary capacitor is C2, the coupling coefficient between the primary coil and the secondary coil is k, and the angular frequency of the AC power is ω, the capacitance value C1 satisfies the following formula (4) and the capacitance value C2 satisfies the following formula (5). C1=1 / (ω 2 ×L1×(1+k)) (4) C2=1 / (ω 2 ×L2×(1+k)) (5) (Form 9) A coil group (GLA), A plurality of primary coils (L1); A secondary coil (L2) whose relative position with respect to the plurality of primary coils is changeable, The plurality of primary coils are arranged in a plane, the secondary coil is capable of receiving power in a non-contact manner from at least one of the plurality of primary coils while changing the relative position; The secondary coil is a first position (P1) where a central axis (CX) of the secondary coil coincides with a central axis (CX) of one target primary coil among the plurality of primary coils; a second position (P2) in which a central axis of the secondary coil does not coincide with a central axis of any of the plurality of primary coils, and in which power can be received from a primary coil group (GL) including at least two of the plurality of primary coils; a first coupling coefficient ka between the target primary coil and the secondary coil at the first position; a specific coupling coefficient sum kbt at a specific second position (P2(id)) where (i) the coupling coefficient between each primary coil of the primary coil group and the secondary coil at the second position, the specific coupling coefficient sum being equal to at least one of a plurality of coupling coefficients corresponding to the plurality of primary coils included in the primary coil group, and (ii) the coupling coefficient sum being the sum of the coupling coefficients between each primary coil of the primary coil group and the secondary coil, is A coil group that satisfies the following equation using a second difference D2 between the first coupling coefficient ka and the specific coupling coefficient sum kbt, and a maximum value Max(ka, kba) between the first coupling coefficient ka and a maximum coupling coefficient sum kba, which is the maximum value of the coupling coefficient sums. D2 < 1 / 2×Max(ka,kba) ···(6) (Form 10) A non-contact power supply system (1) including the coil group according to aspect 9, A plurality of power transmitting resonant circuits (42, 242 to 642) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the plurality of power transmitting resonant circuits includes a respective primary coil of the plurality of primary coils and a primary capacitor (C1), and each of the plurality of power transmitting resonant circuits and the power receiving resonant circuit are configured such that a coupling coefficient between the primary coil and the secondary coil and the power output to the power storage device have a positive correlation. (Form 11) 11. The coil group according to claim 9 or 10, A coil group that satisfies at least one of the following formula (2) and formula (3), where the maximum outer diameter of the primary coil is Dsmax, the minimum outer diameter of the primary coil is Dsmin, the maximum outer diameter of the secondary coil is Drmax, and the minimum outer diameter of the secondary coil is Drmin. Drmax > Dsmax ···(2) Drmin > Dsmin ···(3) (Form 12) 12. The wireless power supply system according to any one of aspects 9 to 11, The contactless power supply system further includes a switching circuit (44) that switches, at the specific second position, a state of the power transmission resonant circuit between a power supply state in which power is supplied from the primary coil to the secondary coil and a non-power supply state in which power is not supplied from the primary coil to the secondary coil. (Form 13) 13. The wireless power supply system according to any one of aspects 10 to 12, Each of the plurality of power transmitting resonant circuits is a parallel resonant circuit in which the primary capacitor is connected in parallel to the primary coil, The power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil. (Form 14) 13. The wireless power supply system according to any one of aspects 10 to 12, The primary capacitor includes a parallel primary capacitor (C1p1, C1p2) connected in parallel with the primary coil, and a series primary capacitor (C1s) connected in series with the primary coil, Each of the plurality of power transmitting resonant circuits is a resonant circuit configured with the primary coil, the parallel primary capacitor, and the series primary capacitor, The power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil. (Form 15) A non-contact power supply system (1) including the coil group according to aspect 9, A plurality of power transmitting resonant circuits (342) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the plurality of power transmitting resonant circuits includes: (i) a series resonant circuit having a primary coil of each of the plurality of primary coils and a primary capacitor (C1) connected in series with the primary coil; and (ii) a coupling circuit (346) having a tertiary coil (L3) capable of magnetically coupling with the primary coil and a tertiary capacitor (C3) connected in parallel with the tertiary coil; and the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil; A contactless power supply system in which each of the multiple power transmitting resonant circuits and the power receiving resonant circuit are configured so that a coupling coefficient between the tertiary coil and the secondary coil has a positive correlation with the power output to the power storage device. (Form 16) A non-contact power supply system (1) including the coil group according to aspect 9, A plurality of power transmitting resonant circuits (442) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the power transmitting resonant circuits includes a primary coil of each of the primary coils, a primary capacitor (C1), a tertiary coil (L3) capable of magnetically coupling with the primary coil, the tertiary coil being connected in series with the primary coil, and a tertiary capacitor (C3) connected in parallel with the tertiary coil; the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil, A contactless power supply system in which each of the multiple power transmitting resonant circuits and the power receiving resonant circuit are configured so that a coupling coefficient between the tertiary coil and the secondary coil has a positive correlation with the power output to the power storage device. (Form 17) 13. The wireless power supply system according to any one of aspects 10 to 12, The power supply further includes an AC power source (11) that supplies AC power having a predetermined operating frequency to the plurality of power transmitting resonant circuits, Each of the plurality of power transmitting resonant circuits is a series resonant circuit in which the primary capacitor is connected in series to the primary coil, the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil, A contactless power supply system in which, when the self-inductance of the primary coil is L1, the capacitance value of the primary capacitor is C1, the self-inductance of the secondary coil is L2, the capacitance value of the secondary capacitor is C2, the coupling coefficient between the primary coil and the secondary coil is k, and the angular frequency of the AC power is ω, the capacitance value C1 satisfies the following formula (4) and the capacitance value C2 satisfies the following formula (5). C1=1 / (ω 2 ×L1×(1+k)) (4) C2=1 / (ω 2 ×L2×(1+k)) (5) [Explanation of symbols]

[0097] 1... non-contact power supply system, 11... AC power source, 42,242-642... power transmission resonant circuit, 81... power reception resonant circuit, C1... power transmission capacitor, C2... power reception capacitor, GLA... coil group, GL... power transmission coil group, L1... power transmission coil, L2... power reception coil, P1... first position, P2... second position

Claims

1. A coil group (GLA), A plurality of primary coils (L1); A secondary coil (L2) whose relative position with respect to the plurality of primary coils is changeable, The plurality of primary coils are arranged in a plane, the secondary coil is capable of receiving power in a non-contact manner from at least one of the plurality of primary coils while changing the relative position; The secondary coil is a first position (P1) where a central axis (CX) of the secondary coil coincides with a central axis (CX) of one target primary coil among the plurality of primary coils; a second position (P2) in which a central axis of the secondary coil does not coincide with a central axis of any of the plurality of primary coils, and in which the secondary coil can receive power from a primary coil group (GL) including at least two of the plurality of primary coils; a first coupling coefficient k a between the target primary coil and the secondary coil at the first position; a maximum coupling coefficient sum kba, which is a sum of coupling coefficients between each primary coil of the primary coil group and the secondary coil at a maximum position (P2(max)) where the sum of coupling coefficients is maximized among the second positions, is A coil group that satisfies the following equation (1) using a first difference D1 between the first coupling coefficient ka and the maximum coupling coefficient sum kba, and a maximum value MAX(ka, kba) between the first coupling coefficient ka and the maximum coupling coefficient sum kba. D1 < 1 / 2 x Max (ka, kba) ... (1)

2. A non-contact power supply system (1) comprising the coil group according to claim 1, A plurality of power transmitting resonant circuits (42, 242 to 642) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the power transmitting resonant circuits includes a primary coil of each of the primary coils and a primary capacitor (C1), A contactless power supply system in which each of the multiple power transmitting resonant circuits and the power receiving resonant circuit are configured so that a coupling coefficient between the primary coil and the secondary coil has a positive correlation with the power output to the power storage device.

3. 2. The coil group according to claim 1, A coil group that satisfies at least one of the following formulas (2) and (3), where the maximum outer diameter of the primary coil is Dsmax, the minimum outer diameter of the primary coil is Dsmin, the maximum outer diameter of the secondary coil is Drmax, and the minimum outer diameter of the secondary coil is Drmin. Drmax>Dsmax...(2) Drmin>Dsmin...(3)

4. The non-contact power supply system according to claim 2, Each of the plurality of power transmitting resonant circuits is a parallel resonant circuit in which the primary capacitor is connected in parallel to the primary coil, The power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil.

5. The non-contact power supply system according to claim 2, The primary capacitor includes a parallel primary capacitor (C1p1, C1p2) connected in parallel with the primary coil, and a series primary capacitor (C1s) connected in series with the primary coil, Each of the plurality of power transmitting resonant circuits is a resonant circuit configured with the primary coil, the parallel primary capacitor, and the series primary capacitor, The power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil.

6. A non-contact power supply system (1) comprising the coil group according to claim 1, A plurality of power transmitting resonant circuits (342) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the plurality of power transmitting resonant circuits includes: (i) a series resonant circuit having a primary coil of each of the plurality of primary coils and a capacitor (C1) connected in series with the primary coil; and (ii) a coupling circuit (346) having a tertiary coil (L3) capable of magnetically coupling with the primary coil and a tertiary capacitor (C3) connected in parallel with the tertiary coil, the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil, A contactless power supply system in which each of the multiple power transmitting resonant circuits and the power receiving resonant circuit are configured so that there is a positive correlation between the coupling coefficient between the tertiary coil and the secondary coil and the power output to the power storage device.

7. A non-contact power supply system (1) comprising the coil group according to claim 1, A plurality of power transmitting resonant circuits (442) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the power transmitting resonant circuits of the plurality of power transmitting resonant circuits includes a respective primary coil of the plurality of primary coils, a primary capacitor (C1) connected in series to the primary coil, and a tertiary coil (L3) capable of magnetic coupling with the primary coil, the tertiary coil being connected in series with the primary coil, and a tertiary capacitor (C3) connected in parallel with the tertiary coil; and the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series to the secondary coil, A contactless power supply system in which each of the multiple power transmitting resonant circuits and the power receiving resonant circuit are configured so that there is a positive correlation between the coupling coefficient between the tertiary coil and the secondary coil and the power output to the power storage device.

8. The non-contact power supply system according to claim 2, The power supply further includes an AC power source (11) that supplies AC power having a predetermined operating frequency to the plurality of power transmitting resonant circuits, Each of the plurality of power transmitting resonant circuits is a series resonant circuit in which the primary capacitor is connected in series to the primary coil, the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil, The self-inductance of the primary coil is L １ , the capacitance value of the primary capacitor is C １ , the self-inductance of the secondary coil is L ２ , the capacitance value of the secondary capacitor is C ２ , the coupling coefficient between the primary coil and the secondary coil is k, and the angular frequency of the AC power is ω, the capacitance value C １ satisfies the following formula (4), and the capacitance value C ２ is a contactless power transfer system that satisfies the following formula (5). C １ =1 / (ω) ２ ×L １ ×(1+k)) ・・・(4) C ２ =1 / (ω) ２ ×L ２ ×(1+k)) ・・・(5)

9. A coil group (GLA), A plurality of primary coils (L1); A secondary coil (L2) whose relative position with respect to the plurality of primary coils is changeable, The plurality of primary coils are arranged in a plane, the secondary coil is capable of receiving power in a non-contact manner from at least one of the plurality of primary coils while changing the relative position; The secondary coil is a first position (P1) where a central axis (CX) of the secondary coil coincides with a central axis (CX) of one target primary coil among the plurality of primary coils; a second position (P2) in which a central axis of the secondary coil does not coincide with a central axis of any of the plurality of primary coils, and in which the secondary coil can receive power from a primary coil group (GL) including at least two of the plurality of primary coils; a first coupling coefficient k a between the target primary coil and the secondary coil at the first position; (i) a specific coupling coefficient sum kbt at a specific second position (P2(id)) where at least one of a plurality of coupling coefficients corresponding to the plurality of primary coils included in the primary coil group, which is a coupling coefficient between each primary coil of the primary coil group and the secondary coil at the second position, and (ii) a coupling coefficient sum which is the sum of the coupling coefficients between each primary coil of the primary coil group and the secondary coil, are equal to each other; A coil group that satisfies the following equation using a second difference D2 between the first coupling coefficient ka and the specific coupling coefficient sum kbt, and a maximum value Max(ka, kba) between the first coupling coefficient ka and a maximum coupling coefficient sum kba, which is the maximum value of the coupling coefficient sum. D2 < 1 / 2 x Max (ka, kba) ... (6)

10. A non-contact power supply system (1) comprising the coil group according to claim 9, A plurality of power transmitting resonant circuits (42, 242 to 642) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the plurality of power transmitting resonant circuits has a respective primary coil of the plurality of primary coils and a primary capacitor (C1), and each of the plurality of power transmitting resonant circuits and the power receiving resonant circuit are configured such that a coupling coefficient between the primary coil and the secondary coil and the power output to the power storage device have a positive correlation.

11. 10. The coil group according to claim 9, A coil group that satisfies at least one of the following formulas (2) and (3), where the maximum outer diameter of the primary coil is Dsmax, the minimum outer diameter of the primary coil is Dsmin, the maximum outer diameter of the secondary coil is Drmax, and the minimum outer diameter of the secondary coil is Drmin. Drmax > Dsmax...(2) Drmin>Dsmin...(3)

12. The contactless power supply system according to claim 10, The wireless power supply system further includes a switching circuit (44) that switches, at the specific second position, a state of the power transmitting resonant circuit between a power supply state in which power is supplied from the primary coil to the secondary coil and a non-power supply state in which power is not supplied from the primary coil to the secondary coil.

13. The contactless power supply system according to claim 10, Each of the plurality of power transmitting resonant circuits is a parallel resonant circuit in which the primary capacitor is connected in parallel to the primary coil, The power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil.

14. The contactless power supply system according to claim 10, The primary capacitor includes a parallel primary capacitor (C1p1, C1p2) connected in parallel with the primary coil, and a series primary capacitor (C1s) connected in series with the primary coil, Each of the plurality of power transmitting resonant circuits is a resonant circuit configured with the primary coil, the parallel primary capacitor, and the series primary capacitor, The power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil.

15. A non-contact power supply system (1) comprising the coil group according to claim 9, A plurality of power transmitting resonant circuits (342) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the plurality of power transmitting resonant circuits includes: (i) a series resonant circuit having a primary coil of each of the plurality of primary coils and a primary capacitor (C1) connected in series with the primary coil; and (ii) a coupling circuit (346) having a tertiary coil (L3) capable of magnetically coupling with the primary coil and a tertiary capacitor (C3) connected in parallel with the tertiary coil; and the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil; A contactless power supply system in which each of the multiple power transmitting resonant circuits and the power receiving resonant circuit are configured so that there is a positive correlation between the coupling coefficient between the tertiary coil and the secondary coil and the power output to the power storage device.

16. A non-contact power supply system (1) comprising the coil group according to claim 9, A plurality of power transmitting resonant circuits (442) corresponding to the plurality of primary coils; a power receiving resonant circuit (81) having the secondary coil and a secondary capacitor (C2); a power storage device (84) that stores the power received by the secondary coil; Each of the power transmitting resonant circuits includes a primary coil of the plurality of primary coils, a primary capacitor (C1), a tertiary coil (L3) that is magnetically coupled to the primary coil, the tertiary coil being connected in series with the primary coil, and a tertiary capacitor (C3) that is connected in parallel with the tertiary coil; the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil, A contactless power supply system in which each of the multiple power transmitting resonant circuits and the power receiving resonant circuit are configured so that there is a positive correlation between the coupling coefficient between the tertiary coil and the secondary coil and the power output to the power storage device.

17. The contactless power supply system according to claim 10, The power supply further includes an AC power source (11) that supplies AC power having a predetermined operating frequency to the plurality of power transmitting resonant circuits, Each of the plurality of power transmitting resonant circuits is a series resonant circuit in which the primary capacitor is connected in series to the primary coil, the power receiving resonant circuit is a series resonant circuit in which the secondary capacitor is connected in series with the secondary coil, The self-inductance of the primary coil is L １ , the capacitance value of the primary capacitor is C １ , the self-inductance of the secondary coil is L ２ , the capacitance value of the secondary capacitor is C ２ , the coupling coefficient between the primary coil and the secondary coil is k, and the angular frequency of the AC power is ω, the capacitance value C １ satisfies the following formula (4), and the capacitance value C ２ is a contactless power transfer system that satisfies the following formula (5). C １ =1 / (ω) ２ ×L １ ×(1+k)) ・・・(4) C ２ =1 / (ω) ２ ×L ２ ×(1+k)) ・・・(5)

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