JP6016654B2 - Wireless power transmission system - Google Patents

Description

  The present invention relates to a wireless power transmission system.

  Patent Document 1 discloses a wireless power transmission apparatus that transmits power between two non-contact electric circuits using electromagnetic induction.

JP-A-8-340285

  By the way, in the technique disclosed in Patent Document 1, there is a problem in that power cannot be efficiently transmitted because power loss in the coil for transmitting power is large. In addition, there is a problem that power cannot be transmitted efficiently when the distance between the coils on the power transmission side and the power reception side is long.

  Therefore, an object of the present invention is to provide a wireless power transmission system that can efficiently transmit power far away.

In order to solve the above problems, the present invention provides a wireless power transmission system that wirelessly transmits AC power from a power transmission device to a power reception device, wherein the power transmission device is disposed at a predetermined distance, The first and second electrodes having a plate-like shape having a total width including the distance of λ / 2π or less that is the near field, and the first and second electrodes and the two output terminals of the AC power generation unit, respectively First and second connection lines that are electrically connected; a first inductor that is inserted between at least one of the first and second electrodes and the two output terminals of the AC power generation unit; The power receiving device is disposed at a predetermined distance, and the third and fourth electrodes having a plate shape having a total width including the predetermined distance of λ / 2π or less, which is a near field, and the third electrode And four input terminals for the fourth electrode and the load And a second inductor inserted between at least one of the third and fourth electrodes and the two input terminals of the load, and At least one of the first to fourth electrodes has a bent portion in which a part of the end portion is bent in a direction away from the opposing electrode, and is configured by the first and second electrodes and the first inductor. The resonance frequency of the power transmission coupler and the resonance frequency of the power reception coupler constituted by the third and fourth electrodes and the second inductor are set to be substantially equal, and the bent portion is substantially perpendicular to the electrode. It is configured to be bent so as to become .
According to such a configuration, it is possible to provide a wireless power transmission system that can efficiently transmit power far away.

Also, according to one aspect of the present invention, the bent portion is bent at the other end portion on the extension line of the electric lines of force formed between the adjacent one end portions of the two electrodes constituting the coupler. It is characterized by being configured.
According to such a configuration, it is possible to efficiently transmit power far away without increasing the projected area of the electrode.

In addition, according to one aspect of the present invention, when the direction connecting the ends of the current path formed in the coupler at the resonance frequency is the direction of the electric field, the width of the bent portion is a direction parallel to the electric field. It is characterized by being 20 to 40% of the length.
According to such a configuration, it is possible to efficiently transmit power farther than the projected area of the electrode.

In a wireless power transmission system that wirelessly transmits AC power from a power transmission device to a power reception device, the power transmission devices are arranged at a predetermined distance, and a total width including the predetermined distance is λ / Flat first and second electrodes having a length of 2π or less, and first and second connection lines that electrically connect the first and second electrodes and the two output terminals of the AC power generation unit, respectively. And a first inductor inserted between at least one of the first and second electrodes and the two output terminals of the AC power generation unit, and the power receiving device is disposed at a predetermined distance The third and fourth electrodes having a plate-like shape having a total width including the predetermined distance of λ / 2π or less that is a near field, and the two input terminals of the third and fourth electrodes and the load. Are electrically connected to each other. A fourth connecting line; and a second inductor inserted between the third and fourth electrodes and at least one of the two input terminals of the load; and at least one of the first to fourth electrodes Has a bent portion with a part of the end bent in a direction away from the opposing electrode, and a resonance frequency of a power transmission coupler constituted by the first and second electrodes and the first inductor, and the first The power receiving coupler configured by the third and fourth electrodes and the second inductor are set to have substantially the same resonance frequency, and the bent portion has a cylindrical shape.
According to such a configuration, it is possible to efficiently transmit power far away while keeping the projected area of the electrode small.

Another aspect of the present invention is characterized in that the radius of the cylindrical shape is 4 to 12% of the length in the direction parallel to the electric field.
According to such a configuration, it is possible to efficiently transmit power farther than the projected area of the electrode.

  According to the present invention, it is possible to provide a wireless power transmission system capable of efficiently transmitting power far away.

It is a figure which shows the detailed structural example of the power transmission apparatus which comprises the wireless power transmission system using a series resonance. It is a figure which shows the structural example of the wireless power transmission system using a series resonance. 3 is an equivalent circuit of the wireless power transmission system shown in FIG. 2. It is a figure which shows the frequency characteristic of the transmission efficiency and reflection loss of the wireless power transmission system shown in FIG. It is a figure which shows the Smith chart of the impedance of the coupler for power transmission shown in FIG. It is a figure which shows the frequency characteristic of transmission efficiency and reflection loss when the distance of the coupler for power transmission shown in FIG. 2 is shortened. FIG. 3 is a diagram showing a Smith chart of impedance of a power transmission coupler when the distance between the power transmission and reception couplers shown in FIG. 2 is shortened. It is a figure which shows the frequency characteristic of transmission efficiency and reflection loss when the distance of the coupler for power transmission and reception shown in FIG. 2 is lengthened. FIG. 3 is a diagram showing a Smith chart of impedance of a power transmission coupler when the distance between the power transmission and reception couplers shown in FIG. 2 is increased. It is a figure which shows the structural example at the time of doubling the area of the electrode shown in FIG. It is a figure which shows the transmission efficiency of the wireless power transmission system shown in FIG. 10, and the frequency characteristic of reflection loss. It is a figure which shows the Smith chart of the impedance of the coupler for power transmission shown in FIG. 1 is a perspective view illustrating a configuration example of a wireless power transmission system according to a first embodiment of the present invention. It is a figure which shows the cross section of 1st Embodiment shown in FIG. 13, and each part dimension. It is a figure which shows the relationship between the bending length and distance of 1st Embodiment shown in FIG. It is a figure for demonstrating the direction of an electric field. It is a figure which shows the electric field distribution of 1st Embodiment shown in FIG. It is a figure which shows the electric field distribution of the form shown in FIG. It is an example of a structure at the time of bending a bending part inside. It is a figure which shows the dimension of each part of 1st Embodiment shown in FIG. It is a figure which shows the relationship between the bending length and distance of the form shown in FIG. It is a perspective view which shows the structural example of the wireless power transmission system which concerns on 2nd Embodiment of this invention. It is a figure which shows the dimension of each part of 2nd Embodiment shown in FIG. It is a figure which shows the relationship between the radius and distance of the bending part of 2nd Embodiment shown in FIG.

  Next, an embodiment of the present invention will be described.

(A) Description of Wireless Transmission System Using Series Resonance Hereinafter, an embodiment of the present invention will be described after describing a wireless transmission system using series resonance.

  FIG. 1 shows a detailed configuration example of a power transmission coupler constituting a wireless power transmission system using series resonance. As shown in this figure, in a wireless power transmission system using series resonance, a power transmission coupler 110 is a table (mainly) of a circuit board 118 formed of an insulating member (dielectric substrate) having a rectangular plate shape. The electrodes 111 and 112 made of a conductive member having a rectangular shape are arranged on the surface 118A. In the example of FIG. 1, no electrode or the like is disposed on the back surface 118 </ b> B of the circuit board 118. As a specific configuration example, for example, electrodes 111 and 112 are formed of a conductive thin film such as copper on a circuit board 118 formed of a glass epoxy board, a glass composite board, or the like. The electrodes 111 and 112 are arranged in parallel at positions separated by a predetermined distance d1. The width D of the electrodes 111 and 112 including the distance d1 is set to be narrower than the near field indicated by λ / 2π when the wavelength of the electric field radiated from these electrodes is λ. .

  One ends of inductors 113 and 114 are connected to the ends of the electrodes 111 and 112 of the circuit board 118 in the short direction. The other ends of the inductors 113 and 114 are connected to one ends of connection lines 115 and 116, respectively. The connection lines 115 and 116 are disposed so as to avoid the regions of the electrodes 111 and 112 and the region sandwiched between them, and are disposed so as to extend in a direction away from these regions (lower left direction in FIG. 1). Yes. More specifically, the rectangular regions of the electrodes 111 and 112 and the region sandwiched between the two electrodes 111 and 112 are arranged so as to avoid the region, and the electrodes 111 and 112 are arranged so as to extend away from these regions. ing. By arranging in this way, interference between the electrodes 111 and 112 and the connection lines 115 and 116 can be reduced, so that a reduction in transmission efficiency can be prevented. The connection lines 115 and 116 are configured by, for example, a coaxial cable or a balanced cable. Note that the other ends of the connection lines 115 and 116 are respectively connected to output terminals of an AC power generation unit (not shown). By connecting the AC power generation unit to the power transmission coupler 110 by the connection lines 115 and 116, a power transmission device is configured.

The power transmission coupler 110 constitutes a series resonance circuit composed of the capacitance C of the capacitor formed by arranging the electrodes 111 and 112 at a predetermined distance d1 and the inductance L of the inductors 113 and 114. It has a unique resonance frequency f _C.

The power receiving coupler 120 has the same configuration as that of the power transmitting coupler 110. On the surface 128A of the circuit board 128, electrodes 121 and 122 and inductors 123 and 124 made of a conductive member having a rectangular shape are arranged. Connection lines 125 and 126 are connected to the other ends of the inductors 123 and 124. The capacitance C of the capacitor formed by the electrodes 121 and 122 and the resonance frequency f _C of the series resonance circuit due to the inductance L of the inductors 123 and 124 are set to be substantially the same as those of the power transmission coupler 110. The connection lines 125 and 126 are configured by, for example, a coaxial cable or a balanced cable. A load (not shown) is connected to the other ends of the connection lines 125 and 126 of the power receiving coupler 120. A power receiving device is configured by connecting a load to the power receiving coupler 120 through the connection lines 125 and 126.

  FIG. 2 is a diagram illustrating a state in which the power transmission coupler 110 and the power reception coupler 120 are arranged to face each other. As shown in this figure, the power transmission coupler 110 and the power reception coupler 120 are arranged so that the circuit boards 118 and 128 are parallel to each other with a distance d2 so that the surfaces 118A and 128A of the circuit boards 118 and 128 face each other. Is done.

  FIG. 3 is a diagram showing an equivalent circuit of the wireless power transmission system 1 shown in FIG. In FIG. 3, the AC power generator 211 generates and outputs AC power having a frequency corresponding to the resonance frequency. The power supply unit load 212 shows a value equal to the characteristic impedance of the connection lines 115 and 116 and the connection lines 125 and 126, and has a value of Z0. The inductor 213 corresponds to the inductors 113 and 114 and has an element value of L1. A resistor 214 indicates a resistor associated with a power transmission side circuit, mainly an inductor, and has an element value of R1. The capacitor 215 is a capacitor having an element value C 1 generated between the electrodes 111 and 112. The capacitor 221 is a capacitor having an element value C 2 generated between the electrodes 121 and 122. The inductor 222 corresponds to the inductors 123 and 124 and has an element value of L2. The resistor 223 indicates a resistor associated with the power receiving side circuit, mainly the inductor, and has an element value of R2. The load 224 is supplied with power output from the AC power generation unit 211 and transmitted through the power transmission coupler and the power reception coupler. The capacitor 241 indicates a capacitor generated between the electrodes 111 and 112 and the electrodes 121 and 122, and has an element value of Cm1. In addition, the load 224 is comprised by the rectifier, the secondary battery, etc., for example. Of course, it may be other than this.

Next, the operation of the wireless power transmission system using the series resonance shown in FIG. 2 will be described. FIG. 4 illustrates transmission from the power transmission coupler 110 to the power reception coupler 120 when the power transmission coupler 110 and the power reception coupler 120 of the wireless power transmission system illustrated in FIG. 2 are disposed to face each other with a distance of 200 mm (d2 = 200 mm). It is a figure which shows the frequency characteristic of efficiency (eta) 21 (= | S21 | ² ) and reflection loss (eta) 11 (= | S11 | ² ). In this figure, the horizontal axis indicates the frequency (MHz) of AC power to be transmitted, and the vertical axis indicates transmission efficiency. In the example shown in FIG. 4, it can be seen that a transmission efficiency of about 95% is achieved around 27 MHz. In FIG. 2, for example, the inductors 113, 114, 123, and 124 each have 13 turns and an inductance value of 2.8 μH, and the circuit boards 118 and 128 have a size (D and L) of 250 ×. The gap d1 between the electrodes 111 and 112 and the electrodes 121 and 122 is 34.4 mm.

  FIG. 5 shows a Smith chart of the impedance S11 of the power transmission coupler 110 of the wireless power transmission system using the series resonance shown in FIG. In this case, the port impedance of the measuring instrument is set to a value equal to the characteristic impedance Z0 (real value) of the connection line. As shown in these figures, in the wireless power transmission system shown in FIG. 2, since the locus of impedance of the power transmission coupler 110 and the power reception coupler 120 passes near the center of the Smith chart circle, transmission is performed in this vicinity. By setting so as to perform the transmission, it is possible to efficiently transmit power while suppressing reflection.

  6 and 7 show transmission efficiency and reflection characteristics when the distance d2 between the power transmission coupler 110 and the power reception coupler 120 of the wireless power transmission system shown in FIG. 2 is set to 100 mm, which is shorter than 200 mm in FIG. And the Smith chart of impedance S11 is shown. As shown in these figures, when the distance d2 between the power transmission coupler 110 and the power reception coupler 120 is set to be short, two peaks occur at frequencies other than the target frequency of 27 MHz, and the locus of the impedance S11. Also, the shape passes through the matching position twice.

  8 and 9 show transmission efficiency and reflection characteristics when the distance d2 between the power transmission coupler 110 and the power reception coupler 120 of the wireless power transmission system shown in FIG. 2 is set to 300 mm, which is longer than 200 mm in FIG. And the Smith chart of impedance S11 is shown. As shown in these drawings, when the distance d2 between the power transmission coupler 110 and the power reception coupler 120 is set to be long, impedance is not matched, so that transmission efficiency is reduced and reflection is increased.

  From the above, there is an optimum value for the distance between the power transmission coupler 110 and the power reception coupler 120, and if it deviates from the optimum value, the power cannot be transmitted efficiently. This will be described with reference to the equivalent circuit shown in FIG. 3. As the distance between the power transmission coupler 110 and the power reception coupler 120 increases, the element value Cm1 of the capacitor 241 decreases. For this reason, mismatching occurs because the input impedance becomes small. As a method for eliminating such mismatching, it is conceivable to increase the area of the electrode in order to increase the element value Cm. Thus, since the coupling coefficient increases by increasing the area of the electrode, the matching distance can be extended, and as a result, the transmission distance can be extended.

  FIG. 10 shows an example in which the area of the coupler is doubled compared to FIG. In this case, since the coupling coefficient increases, even when the transmission distance is 352 mm compared to 200 mm in FIG. 2, as shown in FIGS. 11 and 12, the transmission efficiency and impedance are almost the same as those in FIG. Characteristics can be obtained.

  However, in such a method, the space (projection area) for electrode installation increases. For this reason, for example, there is a problem in equipment for charging an electric vehicle or the like whose installation space is limited. Of course, for applications other than electric vehicles, a smaller size is desirable.

(B) Description of First Embodiment of the Present Invention Next, a basic configuration of a wireless power transmission system according to the first embodiment of the present invention will be described with reference to FIGS. 13 and 14. FIG. 13 is a perspective view for explaining a configuration example of the first embodiment, and FIG. 14 is a diagram showing dimensions and connection states of the first embodiment shown in FIG. In the example shown in FIGS. 13 and 14, the end portions of the electrodes 111, 112, 121, and 122 are bent to form the bent portions 111a, 112a, 121a, and 122a, as compared with FIG. More specifically, the electrodes 111 and 112 constituting the power transmission coupler 110 are on the other side of the extension of the electric lines of force formed between the two adjacent ends of the two electrodes constituting the power transmission coupler 110. The bent portions 111a and 112a are formed at substantially right angles by a length Lr in a direction away from the electrode of the power receiving coupler 120. Similarly, the electrodes 121 and 122 constituting the power receiving coupler 120 are similarly connected to the other electrode on the extension line of the electric lines of force formed between the two adjacent ends of the two electrodes constituting the power receiving coupler 120. A bent portion is provided at the end, and bent portions 121a and 122a are formed at substantially right angles by a length Lr in a direction away from the electrode of the power transmission coupler 110. In this specification, “folding” means not only when bending at a right angle as shown in FIG. 13, but also when bending at an angle other than a right angle (an angle less than 90 degrees and exceeding 90 degrees), This includes cases where the curve is not linear but curved. In FIGS. 13 and 14, only the electrodes are shown to simplify the drawings, but in practice, a dielectric substrate can be used as in FIG.

  FIG. 15 is a diagram showing the relationship between the length Lr of the bent portions 111a, 112a, 121a, 122a of the first embodiment shown in FIG. 13 and the distance of the power transmitting / receiving coupler at the time of matching. In FIG. 15, the horizontal axis indicates the length Lr of the bent portion, and the vertical axis indicates the distance. The rhombus in the graph indicates the inner distance d2 of the power transmission / reception coupler during matching, and the triangle indicates the outer distance d3 of the power transmission / reception coupler during matching. As shown in this figure, when the length Lr of the bent portion is increased, the transmission distance d2 indicated by a rhombus is increased, and the transmission distance is maximized when bent about 75 mm (when Lr = 75 mm). As a result, it is possible to extend the transmission distance without increasing the installation area (projection area) of the coupler by bending the end portion. The outer distance d3 increases substantially linearly as the bending length Lr increases. However, the inclination decreases when the inner distance d2 exceeds Lr = 75 mm at which the inner distance d2 reaches a maximum. Further, the bending length Lr is desirably about 20% to 40% of the length in the direction parallel to the electric field of the coupler in the example of FIG. That is, in the example of FIG. 15, the length of the coupler in the direction parallel to the electric field is 250 mm, so the range of 20% to 40% is approximately 50 mm to 100 mm. In such a range, the effect of bending can be sufficiently expected. Of course, the present invention is not limited to such a range. Here, the direction of the electric field is defined as “the direction in which the“ both ends of the current path ”formed in the coupler at the resonance frequency is“ connected ”. This will be described with reference to the drawings. In FIG. 16, current paths formed in the power transmission coupler 110 and the power reception coupler 120 at the resonance frequency are schematically shown by dotted lines. The “both ends of the current path” are the positions indicated by the inverted inverted triangles (▽) in the figure, and the “direction of connecting” both ends, that is, the “direction of the electric field” is a line segment having arrows at both ends. The directions are Dr1 and Dr2.

  FIG. 17 is a simulation result showing a distribution state of the electric field when the first embodiment shown in FIG. 13 is viewed from the Y direction (Y coordinate is the center of the electrode in the Y direction). FIG. The simulation result (in the case of FIG. 2) is shown. From the comparison of these figures, when the end portion is bent as shown in FIG. 17, the electric field coupling region (the region having a high concentration existing in the portion surrounded by the broken line in the drawing) at the bent end portion increases. Yes. Therefore, by bending the end portion, the electric field coupling region can be increased, and thereby the transmission distance can be extended without increasing the projection area.

  In the first embodiment, the end portion of the electrode is bent in the direction away from the other coupler (outside), but as shown in FIGS. 19 and 20, the electrode is bent in the direction approaching the other coupler (inner side). You can also. However, in this case, since the bent portion protrudes inward (toward the other coupler), as shown in FIG. 21, the transmission distance increases as the length of the bent portion increases, and the outer distance (d3) at the time of matching Increases, but the inner distance (d2) becomes shorter. Therefore, in order to extend the transmission distance without increasing the projected area of the electrode, it is desirable to bend in the direction away from the other coupler (outside) as shown in FIGS.

(C) Description of Second Embodiment of the Present Invention Next, a second embodiment of the present invention will be described with reference to FIG. 22 and FIG. FIG. 22 is a perspective view for explaining a configuration example of the second embodiment, and FIG. 23 is a diagram showing dimensions of each part of the second embodiment shown in FIG. In the second embodiment shown in FIGS. 22 and 23, compared to FIG. 2, cylindrical bent portions 111b, 112b, 121b, and 122b are formed at the ends of the electrodes 111, 112, 121, and 122, respectively. More specifically, the electrodes 111 and 112 constituting the power transmission coupler 110 are configured such that the other end on the extension line of the electric lines of force formed between the two adjacent ends of the two electrodes is for receiving power. Bending portions 111b and 112b are formed by being bent into a cylindrical shape so that the radius is r in the direction away from the electrode of the coupler 120. Similarly, the electrodes 121 and 122 constituting the power receiving coupler 120 have the other end on the extension of the electric lines of force formed between the two adjacent ends of the two electrodes. The bent portions 121b and 122b are formed by being bent into a cylindrical shape with a radius r in a direction away from the electrode 110.

  FIG. 24 is a diagram showing the relationship between the radius r of the cylinder of the bent portion of the second embodiment shown in FIGS. 22 and 23 and the distance of the power transmitting / receiving coupler during matching. In FIG. 24, the horizontal axis indicates the radius r of the cylinder of the bent portion, and the vertical axis indicates the distance. The rhombus in the graph indicates the inner distance d2 of the power transmission / reception coupler during matching, and the triangle indicates the outer distance d3 of the power transmission / reception coupler during matching. As shown in this figure, when the radius r of the cylinder of the bent portion is increased, the transmission distance d2 indicated by diamonds increases, and the transmission distance becomes maximum when the radius is about 20 mm (when r = 20 mm). As a result, it is possible to extend the transmission distance without increasing the installation area (projection area) of the coupler by bending the end into a cylindrical shape. The cylindrical radius r is preferably about 4% to 12% of the length in the direction parallel to the electric field of the coupler in the example of FIG. That is, in the example of FIG. 24, the length of the coupler in the direction parallel to the electric field is 250 mm, so the range of 4% to 12% is about 10 mm to 30 mm. In such a range, the effect of bending can be sufficiently expected. Of course, the present invention is not limited to such a range.

  As described above, according to the embodiment of the present invention, by providing the bent portion, it is possible to increase the transmission distance without increasing the coupling area of the electric field and increasing the projection area. Moreover, according to this embodiment, the strength of the electrode plate can be improved by bending the end portion. For this reason, since the reinforcement for increasing the strength is not necessary, a secondary effect that the cost can be reduced can be expected.

(D) Modified Embodiment In the first embodiment, the end portion is bent at a right angle, but may be an angle other than a right angle, for example. For example, the angle with the electrode may be less than 90 degrees, or the angle may be greater than 90 degrees.

  Further, in the first embodiment, the end portion is bent in a straight line, but the cross section may be bent in a curved shape. In the second embodiment, the end portion has a perfect circular cylindrical shape, but may have an elliptical shape or a polygonal shape.

  In the second embodiment, the end of the formed ellipse is in contact with the flat plate portion of the electrode plate. However, the end portion may be configured not to contact the flat plate portion. Further, as the bent portion, a cylinder may be formed by a member different from the electrode plate, and the cylinder may be connected by welding or the like. Also in the case of the first embodiment, the bent portion may be formed by welding another member instead of bending the electrode.

  Further, in the first and second embodiments, the illustration of the dielectric substrate is omitted in order to omit the drawing, but in practice, the electrodes shown in FIG. 2 or FIG. 22 are formed on the dielectric substrate. Can do.

  In the first and second embodiments, the bent portion is provided on all of the electrodes 111, 112, 121, and 122, but may be provided on at least one of them. For example, a bent portion may be provided only in the power receiving coupler 120. It should be noted that even if the bent portions are not provided on all the electrode plates, the power transmission coupler 110 and the power reception coupler 120 may be set to have the same resonance frequency. Moreover, you may make it provide both the bending part of 1st Embodiment, and the bending part of 2nd Embodiment combining.

  Moreover, in 1st and 2nd embodiment, although the bending part was provided in the outer edge part (outer edge part of the X direction of a figure) of electrode 111,112,121,122, For example, it can be provided at the end in the Y direction.

  Further, in each of the above embodiments, the two inductors 113 and 114 are inserted between the connection lines 115 and 116 and the electrodes 111 and 112, but they may be inserted in either one of them. Similarly, although the two inductors 123 and 124 are inserted between the connection lines 125 and 126 and the electrodes 121 and 122, they may be inserted into any one of these.

  In the above embodiment, the inductor is configured by winding a conductor wire in a cylindrical shape. For example, the inductor has a shape meandering on a plane as used in a microstrip line. Further, it may be configured by a spiral shape on a plane.

110 Coupler for Power Transmission 111, 112 Electrode 111a, 112a Bent Part 113, 114 Inductor 115, 116 Connection Line 120 Coupler for Power Reception 121, 122 Electrode 121a, 122a Bent Part 123, 124 Inductor 125, 126 Connection Line

Claims (5)

In a wireless power transmission system that transmits AC power wirelessly from a power transmitting device to a power receiving device,
The power transmission device is:
Flat plate-shaped first and second electrodes which are arranged at a predetermined distance and have a total width including the predetermined distance of λ / 2π or less which is a near field;
First and second connection lines that electrically connect the first and second electrodes and the two output terminals of the AC power generation unit, respectively;
A first inductor inserted between the first and second electrodes and at least one of the two output terminals of the AC power generation unit;
The power receiving device is:
Flat plate-shaped third and fourth electrodes that are arranged at a predetermined distance and have a total width including the predetermined distance of λ / 2π or less that is a near field;
Third and fourth connection lines that electrically connect the third and fourth electrodes and the two input terminals of the load, respectively;
A second inductor inserted between the third and fourth electrodes and at least one of the two input terminals of the load;
At least one of the first to fourth electrodes has a bent portion in which a part of the end portion is bent in a direction away from the opposing electrode, and is configured by the first and second electrodes and the first inductor. The resonance frequency of the power transmission coupler is set to be substantially equal to the resonance frequency of the power reception coupler constituted by the third and fourth electrodes and the second inductor, and the bent portion is substantially the same as the electrode. A wireless power transmission system, wherein the wireless power transmission system is configured to be bent at a right angle .   The bent portion is formed by bending the other end portion on an extension line of an electric field line formed between adjacent one end portions of the two electrodes constituting the coupler. The wireless power transmission system according to claim 1. When the direction connecting the ends of the current path formed in the coupler at the resonance frequency is the direction of the electric field, the width of the bent portion is 20 to 40% of the length in the direction parallel to the electric field. The wireless power transmission system according to claim 1 or 2 . In a wireless power transmission system that transmits AC power wirelessly from a power transmitting device to a power receiving device,
The power transmission device is:
Flat plate-shaped first and second electrodes which are arranged at a predetermined distance and have a total width including the predetermined distance of λ / 2π or less which is a near field;
First and second connection lines that electrically connect the first and second electrodes and the two output terminals of the AC power generation unit, respectively;
A first inductor inserted between the first and second electrodes and at least one of the two output terminals of the AC power generation unit;
The power receiving device is:
Flat plate-shaped third and fourth electrodes that are arranged at a predetermined distance and have a total width including the predetermined distance of λ / 2π or less that is a near field;
Third and fourth connection lines that electrically connect the third and fourth electrodes and the two input terminals of the load, respectively;
A second inductor inserted between the third and fourth electrodes and at least one of the two input terminals of the load;
At least one of the first to fourth electrodes has a bent portion in which a part of the end portion is bent in a direction away from the opposing electrode, and is configured by the first and second electrodes and the first inductor. The resonance frequency of the power transmission coupler is set to be substantially equal to the resonance frequency of the power reception coupler constituted by the third and fourth electrodes and the second inductor,
The wireless power transmission system, wherein the bent portion has a cylindrical shape . The wireless power transmission system according to claim 4, wherein a radius of the cylindrical shape is 4 to 12% of a length in a direction parallel to the electric field .

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