Wireless power transmission system

Abstract

To provide a wireless power transmission system which ensures the degree of freedom in position and rotation of a power receiving coupler and also has increased power transmission efficiency.SOLUTION: There is provided a wireless power transmission system 1 that wirelessly transmits power from a power source 4 to a load 5 via a power transmitting coupler 2 and a power receiving coupler 3. The power transmitting coupler 2 has a first electrode 21 and a second electrode 22 respectively connected to two terminals of the power source 4. The power receiving coupler 3 has a third electrode 31 and a fourth electrode 32 respectively connected to two terminals of the load 5. The third electrode 31 is arranged between the first electrode 21 and the fourth electrode 32. The second electrode 22 is arranged at a position not overlapped on a region in which the first electrode 21, the third electrode 31, and the fourth electrode 32 are projected in a case where the first electrode 21, the third electrode 31, and the fourth electrode 32 are projected in a direction that they are overlapped.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wireless power transmission system.

Background Art

[0002] In recent years, with the spread of mobile phones, electric vehicles, etc., the development of an electric field resonance type wireless power transmission system that supplies power wirelessly has been actively carried out. For example, a technique has been proposed in which an electric field resonance is generated by a coupler composed of two electrodes on the power transmission side and two electrodes on the power reception side, and power is transmitted wirelessly.

[0003] Patent Document 1 discloses a wireless power transmission system that is strong against positional displacement and rotational displacement between the electrodes of the power transmission coupler and the electrodes of the power reception coupler. In the wireless power transmission system of Patent Document 1, a pair of electrodes of the power transmission coupler are arranged to face each other, a pair of electrodes of the power reception coupler are arranged to face each other, and the electrodes of the power transmission coupler and the electrodes of the power reception coupler are configured to face each other.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, there has been a demand for a configuration that can achieve both ensuring the freedom of position and rotation of the power reception coupler with respect to the power transmission coupler and improving the power transmission efficiency without increasing the size of the configuration on the power transmission side.

[0006] An object of the present invention is to provide a wireless power transmission system that can achieve both ensuring the freedom of position and rotation of the power reception coupler with respect to the power transmission coupler and increasing the power transmission efficiency.

Means for Solving the Problems

[0007] (1) The wireless power transmission system according to the present invention is a wireless power transmission system that wirelessly transmits power from a power source to a load through a power transmission coupler and a power reception coupler, wherein the power transmission coupler has a first electrode and a second electrode connected to two terminals of the power source, respectively, and the power reception coupler has a third electrode and a fourth electrode connected to two terminals of the load, respectively, wherein the third electrode is positioned between the first electrode and the fourth electrode, and the second electrode is positioned at a location that does not overlap with the area where the first electrode, third electrode and fourth electrode are projected when projected in a direction in which the first electrode, third electrode and fourth electrode overlap.

[0008] (2) In the wireless power transmission system of (1), the transmitting coupler has at least one inductor between it and the power source, and the receiving coupler has at least one inductor between it and the load, and the transmitting coupler and the receiving coupler are in electric field resonance.

[0009] (3) In the wireless power transmission system of (1) or (2), the first electrode, the second electrode, the third electrode, and the fourth electrode have a flat plate shape.

[0010] (4) In the wireless power transmission system of (3), the planar projected area of ​​the first electrode is equal to the planar projected area of ​​the second electrode.

[0011] (5) In the wireless power transmission system of (3), the planar projected area of ​​the third electrode is equal to the planar projected area of ​​the fourth electrode.

[0012] (6) In the wireless power transmission system of (1) or (2), the planar projected areas of the third electrode and the fourth electrode are the same as or smaller than the planar projected area of ​​the first electrode.

[0013] In the wireless power transmission system of (7)(3), the first electrode and the second electrode are arranged on the same plane.

[0014] In the wireless power transmission system of (8)(7), the second electrode is formed by partially cutting out a portion of it, and the first electrode is placed in the cut-out portion.

[0015] (9) In the wireless power transmission system of (1) or (2), the third electrode and the fourth electrode are similar in shape.

[0016] (10) In the wireless power transmission system of (1) or (2), at least one of the power transmitting coupler and the power receiving coupler is covered with a grounded electrode.

[0017] (11) In the wireless power transmission system of (1) or (2), an insulating coating is formed on one surface of the first electrode and the second electrode, or on one surface of the third electrode.

[0018] (12) The wireless power transmission system is a wireless power transmission system that wirelessly transmits power from a power source to a first load and a second load through a power transmission coupler and a power reception coupler, wherein the power transmission coupler has a first electrode and a second electrode connected to two terminals of the power source, respectively, and the power reception coupler has a third electrode and a fourth electrode connected to two terminals of the first load, respectively, and a fifth electrode and a sixth electrode connected to two terminals of the second load, respectively, wherein the third electrode is positioned between the first electrode and the fourth electrode, and the second electrode is positioned at a location that does not overlap with the area where the first electrode, third electrode and fourth electrode are projected when projected in a direction in which they overlap, and the fifth electrode is positioned between the second electrode and the sixth electrode, and the first electrode is positioned at a location that does not overlap with the area where the second electrode, fifth electrode and sixth electrode are projected when projected in a direction in which they overlap. [Effects of the Invention]

[0019] According to the present invention, a wireless power transmission system is provided that achieves both the assurance of freedom of position and rotation of the power receiving coupler relative to the power transmitting coupler and high power transmission efficiency. [Brief explanation of the drawing]

[0020] [Figure 1]It is a perspective view showing an overview of a wireless power transmission system according to a first embodiment of the present invention. [Figure 2] It is a perspective view showing a configuration of a wireless power transmission system according to a first embodiment of the present invention. [Figure 3] It is a perspective view showing a first comparative example of a wireless power transmission system according to a first embodiment of the present invention. [Figure 4] It is a perspective view showing a second comparative example of a wireless power transmission system according to a first embodiment of the present invention. [Figure 5] It is a perspective view showing a second example of a second modification of a wireless power transmission system according to a first embodiment of the present invention. [Figure 6] It is a perspective view showing a first example of a third modification of a wireless power transmission system according to a first embodiment of the present invention. [Figure 7] It is a perspective view showing a first example of a fourth modification of a wireless power transmission system according to a first embodiment of the present invention. [Figure 8] It is a perspective view showing a second example of a fourth modification of a wireless power transmission system according to a first embodiment of the present invention. [Figure 9] It is a perspective view showing a first example of a fifth modification of a wireless power transmission system according to a first embodiment of the present invention. [Figure 10] It is a perspective view showing a second example of a fifth modification of a wireless power transmission system according to a first embodiment of the present invention. [Figure 11] It is a perspective view showing a sixth modification of a wireless power transmission system according to a first embodiment of the present invention. [Figure 12] It is a perspective view showing a first example of a seventh modification of a wireless power transmission system according to a first embodiment of the present invention. [Figure 13] It is a perspective view showing a second example of a seventh modification of a wireless power transmission system according to a first embodiment of the present invention. [Figure 14] It is a perspective view showing a third example of a seventh modification of a wireless power transmission system according to a first embodiment of the present invention. [Figure 15] It is a perspective view showing an eighth modification of a wireless power transmission system according to a first embodiment of the present invention. [Figure 16] This is a perspective view showing a modified example 9 of the wireless power transmission system according to the first embodiment of the present invention. [Figure 17] This is a perspective view showing a first example of a modified example 10 of the wireless power transmission system according to the first embodiment of the present invention. [Figure 18] This is a perspective view showing a second example of a modified example 10 of the wireless power transmission system according to the first embodiment of the present invention. [Figure 19] This is a perspective view of a wireless power transmission system according to a second embodiment of the present invention. [Modes for carrying out the invention]

[0021] Hereinafter, an electric field resonance type wireless power transmission device and an electric field resonance type wireless power transmission system according to embodiments of the present invention will be described with reference to the drawings. In each figure, the same components are denoted by the same reference numerals. In the Cartesian coordinate system XYZ shown in the figures, the direction parallel to the electrode plane constituting the power receiving coupler 3 is the X-axis direction, the direction perpendicular to the X-axis is the Y-axis direction, and the direction perpendicular to both the X-axis and Y-axis is the Z-axis direction. Hereafter, this coordinate system will be used as appropriate in the explanation.

[0022] (First Embodiment) Figure 1 is a perspective view showing an overview of the wireless power transmission system 1 according to the present invention. The wireless power transmission system 1 is a wireless power transmission system that wirelessly transmits power from a power source 4 to a load 5 through a power transmission coupler 2 and a power reception coupler 3. The power transmission coupler 2 has a first electrode 21 and a second electrode 22, each connected to two terminals of the power source 4. The power reception coupler 3 has a third electrode 31 and a fourth electrode 32, each connected to two terminals of the load 5. The third electrode 31 is positioned between the first electrode 21 and the fourth electrode 32. When the first electrode 21, the third electrode 31 and the fourth electrode 32 are projected in a direction in which they overlap, the second electrode 22 is positioned at a location that does not overlap with the area where the first electrode 21, the third electrode 31 and the fourth electrode 32 are projected. In the following, "the planes of electrodes facing each other" will be expressed as "electrodes facing each other".

[0023] Power source 4 could be, for example, a high-frequency power supply that outputs high-frequency power. Load 5 could be, for example, a battery or motor built into an electric vehicle, matching circuits, rectifier circuits, or DC / DC converters (DC voltage conversion units) that make up various electronic devices.

[0024] The power transmission coupler 2 has at least one inductor 6 between it and the power supply 4, and the power receiving coupler 3 has at least one inductor 6 between it and the load 5. In the example shown in Figure 1, a first inductor 6a is provided between the power supply 4 and the first electrode 21 or the second electrode 22. A second inductor 6b is provided between the load 5 and the fourth electrode 32 or the third electrode 31. By providing the first inductor 6a and the second inductor 6b, the high-frequency power output from the power supply 4 is efficiently supplied to the load 5 via the power transmission coupler 2 and the power receiving coupler 3 due to the effect of electric field resonance. In this case, the wireless power transmission system 1 is of the electric field resonance type. Note that wireless power transmission can be performed even without providing the first inductor 6a and the second inductor 6b.

[0025] In Figure 1, the area of ​​each electrode when viewed from the Z-axis direction, specifically the first electrode 21, second electrode 22, third electrode 31, and fourth electrode 32, will be referred to as the planar projected area on the XY plane (hereinafter simply referred to as "planar projected area"). The first electrode 21 and the second electrode 22 have the same planar projected area, and the third electrode 31 and the fourth electrode 32 also have the same planar projected area. On the other hand, the planar projected areas of the third electrode 31 and the fourth electrode 32, which face the first electrode 21, are the same as or smaller than the planar projected area of ​​the first electrode 21. In the example shown in Figure 1, the planar projected area of ​​the third electrode 31 is approximately 1 / 4 of the planar projected area of ​​the first electrode 21.

[0026] Let's consider the case where the receiving coupler 3 rotates in the XY plane around the center of its electrodes. In the configuration according to the embodiment of the present invention shown in Figure 1, even if the receiving coupler 3 rotates, the third electrode 31 of the receiving coupler 3 maintains almost the same opposing relationship with the first electrode 21. Furthermore, although not shown in Figure 1, let's consider the case where the center of the third electrode 31 of the receiving coupler 3 coincides with the center of the first electrode 21 of the transmitting coupler 2. Even if the receiving coupler 3 rotates in the plane, the third electrode 31 of the receiving coupler 3 maintains the opposing state with the first electrode 21 of the transmitting coupler 2. That is, no matter what angle the receiving coupler 3 is set to in the plane, the opposing relationship between the third electrode 31 of the receiving coupler 3 and the first electrode 21 of the transmitting coupler 2 is maintained. The capacitance formed between the third electrode 31 and the first electrode 21 of the transmitting coupler 2 remains unchanged, and the power transmission efficiency of the wireless power transmission system 1 does not change.

[0027] Furthermore, the position of the power receiving coupler 3 is free within a plane parallel to the first electrode 21, i.e., a plane parallel to the XY plane in Figure 1, as long as the opposing relationship between the first electrode 21 and the third electrode 31 is maintained. Also, although Figure 1 shows an example in which the third electrode 31 is used opposite the first electrode 21, it is not limited to this, and the fourth electrode 32 may also be used opposite the first electrode 21.

[0028] As described above, the power receiving coupler 3 has freedom of position and rotation relative to the power transmitting coupler 2.

[0029] Next, we will describe the results of our investigation into the power transmission efficiency between the power transmission coupler 2 and the power receiving coupler 3 in the above configuration.

[0030] Figure 2 is a perspective view of the wireless power transmission system 1 shown in Figure 1, observed from the negative direction of the Y-axis in Figure 1. It is preferable that the planar projected areas of the receiving electrodes, the third electrode 31 and the fourth electrode 32, are equal to or smaller than the planar projected areas of the transmitting electrodes, the first electrode 21 and the second electrode 22. Figure 1 schematically shows the case where the planar projected areas of the receiving electrodes, the third electrode 31 and the fourth electrode 32, are smaller than the planar projected areas of the transmitting electrodes, the first electrode 21 and the second electrode 22. Figure 2 schematically shows the case where the planar projected areas of the receiving electrodes, the third electrode 31 and the fourth electrode 32, are equal to the planar projected areas of the transmitting electrodes, the first electrode 21 and the second electrode 22. Furthermore, the XYZ coordinate system in Figure 2 is set as shown in the lower left of Figure 2.

[0031] As shown in Figure 2, the first electrode 21 and the third electrode 31 are separated by a distance d1. Figure 3 is a first comparative example (hereinafter referred to as Comparative Example 1) with respect to the configuration in Figure 2. In Comparative Example 1, the first electrode 21 and the second electrode 22 are arranged on the same plane (on a plane parallel to the XY plane) with a predetermined gap between them, and the third electrode 31 and the fourth electrode 32 are arranged on the same plane (on a plane parallel to the XY plane) with a predetermined gap between them. The first electrode 21 and the third electrode 31, and the second electrode 22 and the fourth electrode 32 are facing each other. The first electrode 21 and the third electrode 31, and the second electrode 22 and the fourth electrode 32 are separated by a distance d1.

[0032] Here, we will explain the misalignment between the power transmission coupler 2 and the power reception coupler 3 (for details, see Japanese Patent Publication No. 2014-150155, Figures 5-9, paragraph 0030). For example, if the power transmission coupler 2 and the power reception coupler 3 are rotated 90 degrees and positioned, the transmission efficiency becomes 0 and the reflection loss becomes close to 1. As a result, most of the power input to the power transmission coupler 2 is reflected and not transmitted to the power reception coupler 3. In addition, the input impedance becomes low, resulting in a state of impedance mismatch. For this reason, if the power transmission coupler 2 and the power reception coupler 3 are rotated 90 degrees and positioned, it becomes difficult to transmit power. Figure 4 shows Comparative Example 2 to the configuration in Figure 2. In Comparative Example 2, the first electrode 21 and the second electrode 22 face each other, and the third electrode 31 and the fourth electrode 32 face each other. Furthermore, the first electrode 21 and the third electrode 31 face each other.

[0033] Here, the configuration shown in Comparative Example 2 is more resistant to misalignment between the power transmission coupler 2 and the power receiving coupler 3 compared to the configuration shown in Comparative Example 1, but its power transmission efficiency is lower compared to the configuration according to the embodiment of the present invention.

[0034] Computer simulations were performed for this embodiment, Comparative Example 1, and Comparative Example 2 to calculate the power transmission efficiency. The simulation was performed with the power supply 4 frequency set to 13.56 MHz, each electrode material being pure aluminum with a thickness of 1 mm, the resonant coil Q value being 300, and the coupler (electrode) size being the same. As a result, the calculated power transmission efficiency was 96.0% for this embodiment, 99.3% for Comparative Example 1, and 88.2% for Comparative Example 2. From these results, it was found that the wireless power transmission system 1 according to this embodiment can achieve the same power transmission efficiency as the conventional example seen in Comparative Example 1. Furthermore, it was found that the power transmission efficiency of the wireless power transmission system 1 according to this embodiment is improved compared to the power transmission efficiency of the wireless power transmission system 1 in Comparative Example 2.

[0035] As described above, this embodiment provides a wireless power transmission system 1 that achieves both ensuring freedom of position and rotation of the power receiving coupler 3 relative to the power transmitting coupler 2 and improving power transmission efficiency.

[0036] (Variation 1) In the first embodiment, the third electrode 31 and the fourth electrode 32 had smaller planar projected areas than the first electrode 21 and the second electrode 22. In the first modified example, the planar projected areas of the first electrode 21 and the second electrode 22 are equal, and the planar area of ​​the third electrode 31 and the fourth electrode 32 is equal to that of the first electrode 21 and the second electrode 22. The first inductor 6a may be configured to be connected in series between one terminal of the power supply 4 and the first electrode 21, or it may be connected in series between the other terminal of the power supply 4 and the second electrode 22. The second inductor 6b may be connected in series between one terminal of the load 5 and the third electrode 31, or it may be connected in series between the other terminal of the load 5 and the fourth electrode 32. With this configuration, even if the third electrode 31 and the fourth electrode 32 constituting the power receiving coupler 3 rotate to a certain extent (a few degrees) relative to the power transmitting coupler 2 in a plane parallel to the XY plane, the power transmission efficiency can be maintained at a high level.

[0037] (Modification 2) In the first modified example, the first inductor 6a and the second inductor 6b are provided in the same manner as in the first embodiment. In modified example 2, as shown in Figure 5, neither the first inductor 6a nor the second inductor 6b are provided. In this case, although the power transmission efficiency is lower compared to the first embodiment, wireless power transmission is still possible, and the advantage of a reduced number of components is obtained.

[0038] (Variation 3) In the above embodiment, the first electrode 21, second electrode 22, third electrode 31, and fourth electrode 32 were all planar electrodes, but depending on the conditions of the location where the electrodes are placed, these electrodes may be bent or curved. Modification 3 shows an example in which a bent first electrode 21 and a bent second electrode 22 are placed opposite each other, as shown in Figure 6. The configuration according to Modification 3 allows for the shape of the electrodes on the power transmission side (first electrode 21, second electrode 22) to be freely changed according to the conditions of the location where they are placed, and is expected to be adopted in various locations.

[0039] (Modification 4) In the first embodiment and its modified form described above, the planar projected areas of the third electrode 31 and the fourth electrode 32 of the power receiving coupler 3 were set to be equal. In modified form 4, as shown in Figures 7 and 8, the planar projected areas of the third electrode 31 and the fourth electrode 32 are different. In the example in Figure 7, the planar projected area of ​​the fourth electrode 32 is smaller than that of the third electrode 31. For example, the planar projected area of ​​the fourth electrode 32 is half the size of the planar projected area of ​​the third electrode 31. Note that the size is not limited to half, and could be 1 / 3 or 1 / 4, etc.

[0040] In the example shown in Figure 8, the planar projected area of ​​the fourth electrode 32 is larger than that of the third electrode 31. For example, the planar projected area of ​​the fourth electrode 32 is twice as large as that of the third electrode 31. However, the size is not limited to twice; it could be 1.5 times or 3 times, for example. Also, in the examples in Figures 7 and 8, the third electrode 31 and the fourth electrode 32 are both rectangular and similar in shape, but they may be different in shape, or they may not be similar in shape. The configuration according to Modification 4 has the advantage that, as long as resonance is possible, the planar projected areas of the fourth electrode 32 and the third electrode 31 may be different, and the options for the shape (design) of the power receiving coupler 3 are broadened.

[0041] (Variation 5) In the first embodiment and its modified form described above, an example was shown in which the planar projected areas of the first electrode 21 and the second electrode 22 of the power transmission coupler 2 are equal. In modified form 5, as shown in Figures 9 and 10, an example is shown in which the planar projected areas of the first electrode 21 and the second electrode 22 of the power transmission coupler 2 are different. In the example shown in Figure 9, the planar projected area of ​​the second electrode 22 is smaller than that of the first electrode 21, and the lengths of the adjacent sides of the second electrode 22 and the first electrode 21 are the same. For example, the planar projected area of ​​the second electrode 22 is half the size of the planar projected area of ​​the first electrode 21. Note that the size is not limited to half, and may be 1 / 3 or 1 / 4, etc. Also, in Figure 9, the planar projected areas of the third electrode 31 and the fourth electrode 32 are shown to be equivalent to the planar projected area of ​​the first electrode 21, but are not limited to this.

[0042] In the example shown in Figure 10, the lengths of the adjacent sides of the second electrode 22 and the first electrode 21 are different, with the length of the side of the second electrode 22 adjacent to the first electrode 21 being shorter than the length of the side of the first electrode 21 adjacent to the second electrode 22. For example, the planar projected area of ​​the second electrode 22 is 1 / 4 the size of the planar projected area of ​​the first electrode 21. Note that the size is not limited to 1 / 4, but could be 1 / 2 or 1 / 3, etc. Also, in Figure 10, the planar projected areas of the third electrode 31 and the fourth electrode 32 are shown to be smaller than the planar projected area of ​​the first electrode 21, but this is not limited to this. In the configuration relating to Modification 5, the planar projected areas of the first electrode 21 and the second electrode 22 may be different as long as resonance is possible, which has the advantage of expanding the options for the shape (design) of the power transmission coupler 2.

[0043] (Experimental variation 6) In Modification 6, the wireless power transmission system 1 is configured such that the second electrode 22 surrounds the first electrode 21. A portion of the second electrode 22 is formed by cutting out a shape, and the first electrode 21 is positioned in the cut-out portion. In the example shown in Figure 11, the first electrode 21 is rectangular in plan view, and the second electrode 22 is formed in an annular shape to surround the first electrode 21, with both the outer and inner circumferences of the annular second electrode 22 being rectangular. The shape of the second electrode 22 is not necessarily limited to a rectangle and can be any shape that suits the situation.

[0044] (Example 7) In the embodiments and their modifications described above, the first electrode 21 and the second electrode 22 were mainly arranged on the same plane. In modification 7, as shown in Figures 12, 13, and 14, the first electrode 21 and the second electrode 22 are not arranged on the same plane. In the example shown in Figure 12, the second electrode 22 is positioned perpendicular to the first electrode 21 and on the side away from the third electrode 31 with respect to the first electrode 21. In Figure 12, the planar projected area of ​​the second electrode 22 is shown to be smaller than the planar projected area of ​​the first electrode 21, but this is not limited to that. Also, in Figure 12, the second electrode 22 is shown perpendicular to the first electrode 21, but this is not limited to that.

[0045] In the example shown in Figure 13, the second electrode 22 is positioned perpendicular to the first electrode 21 and on the side of the first electrode 21 that is close to the third electrode 31 and the fourth electrode 32. In Figure 13, the planar projected area of ​​the first electrode 21 and the planar projected area of ​​the second electrode 22 are shown to be larger than the planar projected area of ​​the third electrode 31 and the planar projected area of ​​the fourth electrode 32, but this is not limited to the example. Also, in Figure 13, the second electrode 22 is shown perpendicular to the first electrode 21, but this is not limited to the example. In the example shown in Figure 14, the second electrode 22 is positioned on a plane that is parallel to the plane on which the first electrode 21 is positioned and does not overlap with the first electrode 21. The plane on which the first electrode 21 is positioned and the plane on which the second electrode 22 is positioned are separated by a distance d2.

[0046] In Figure 14, the planar projected areas of the first electrode 21 and the second electrode 22 are shown to be equivalent to the planar projected areas of the third electrode 31 and the fourth electrode 32, but the invention is not limited to this. Also, in Figure 14, the position of the second electrode 22 is shown to be lower than the position of the first electrode 21, but the invention is not limited to this. The configuration according to Modification 7 has the advantage that, if resonance is possible, the position where the first electrode 21 is placed and the position where the second electrode 22 is placed are not limited to being on the same plane, and the options for the shape (design) of the power transmission coupler 2 are broadened.

[0047] (Variation 8) In the above embodiments and their modifications, the power transmission coupler 2, the power receiving coupler 3, the first electrode 21, the second electrode 22, the third electrode 31, and the fourth electrode 32 are not all covered by a grounded shield case 7. In modification 8, at least one of the power transmission coupler 2, the power receiving coupler 3, the first electrode 21, the second electrode 22, the third electrode 31, and the fourth electrode 32 is covered by a grounded shield case 7 (electrode). For example, at least one of the power transmission coupler 2 and the power receiving coupler 3 is covered by a grounded shield case 7. As shown in Figure 15, the first electrode 21 and the second electrode 22 may be covered by a grounded shield case 7 except for the surface facing the power receiving coupler 3.

[0048] (Extreme variation 9) As a 9th modification, the first electrode 21 and second electrode 22 of the power transmission coupler 2, and the third electrode 31 and fourth electrode 32 of the power receiving coupler 3 are configured to be surrounded by a grounded guard electrode 23 provided on the plane in which they are arranged. As shown in Figure 16, the first electrode 21 and the second electrode 22 may also be configured to be surrounded by the grounded guard electrode 23.

[0049] (Variation 10) In the first embodiment and its modified form described above, the first electrode 21, second electrode 22, third electrode 31, and fourth electrode 32 all had their electrode surfaces exposed to the atmosphere. In modified form 10, either the electrode surfaces of the first electrode 21 and second electrode 22 of the power transmission coupler 2 facing the power receiving coupler 3, or the electrode surfaces of the third electrode 31 and fourth electrode 32 of the power receiving coupler 3 facing the power transmission coupler 2, are covered with at least an insulating coating 8. As shown in Figure 17, the surfaces of the first electrode 21 and second electrode 22 (surfaces of the power transmission coupler 2) may be covered with a first insulating coating 8a. Alternatively, as shown in Figure 18, the surface of the third electrode 31 (surface of the power receiving coupler 3) may be covered with a second insulating coating 8b.

[0050] (Second Embodiment) In the first embodiment and its modified examples, Modifications 1 to 10, the first electrode 21 faced the third electrode 31, but the second electrode 22 did not have a facing electrode. In contrast, in the wireless power transmission system 1 according to the second embodiment, as illustrated in Figure 19, the second electrode 22 faces the fifth electrode 33 of the power receiving coupler 3, and the third electrode 31 is positioned between the first electrode 21 and the fourth electrode 32. When the first electrode 21, the third electrode 31, and the fourth electrode 32 are projected in an overlapping direction, the second electrode 22 is positioned in a location that does not overlap with the area where the first electrode 21, the third electrode 31, and the fourth electrode 32 are projected, and the fifth electrode 33 is positioned between the second electrode 22 and the sixth electrode 34. When the second electrode 22, the fifth electrode 33, and the sixth electrode 34 are projected in an overlapping direction, the first electrode 21 is positioned in a location that does not overlap with the area where the second electrode 22, the fifth electrode 33, and the sixth electrode 34 are projected.

[0051] The power receiving coupler 3 has a third electrode 31, a fourth electrode 32, a fifth electrode 33, and a sixth electrode 34. The power receiving coupler 3 supplies power to two loads 5. The two loads 5 are distinguished as the first load 5a and the second load 5b. The third electrode 31 and the fourth electrode 32 face each other and supply power to the first load 5a. The fifth electrode 33 and the sixth electrode 34 face each other and supply power to the second load 5b. Although Figure 19 shows an example in which the power receiving coupler 3 is composed of two units, the configuration is not limited to this, and if the power receiving electrodes are smaller than the power transmitting electrodes, the power receiving coupler 3 may be composed of three or more units.

[0052] Although not shown in Figure 19, the modified forms shown in Modification 1 to Modification 10 above may also be applied to the wireless power transmission system 1 according to this second embodiment. In the power transmission coupler 2, a configuration in which the first inductor 6a is not provided may be adopted.

[0053] The field resonance type wireless power transmission system according to the embodiment of the present invention described above provides the following effects.

[0054] A wireless power transmission system 1 according to one embodiment of the present invention is a wireless power transmission system 1 that wirelessly transmits power from a power source 4 to a load 5 through a power transmission coupler 2 and a power reception coupler 3, wherein the power transmission coupler 2 has a first electrode 21 and a second electrode 22 connected to two terminals of the power source 4, respectively, and the power reception coupler 3 has a third electrode 31 and a fourth electrode 32 connected to two terminals of the load 5, respectively, wherein the third electrode 31 is positioned between the first electrode 21 and the fourth electrode 32, and the second electrode 22 is positioned at a location that does not overlap with the area where the first electrode 21, the third electrode 31 and the fourth electrode 32 are projected when projected in a direction in which the first electrode 21, the third electrode 31 and the fourth electrode 32 overlap.

[0055] This provides a wireless power transmission system 1 that achieves both the freedom of position and rotation of the power receiving coupler 3 relative to the power transmitting coupler 2 and high power transmission efficiency.

[0056] In the wireless power transmission system 1, the transmitting coupler 2 has at least one inductor 6 between it and the power source 4, and the receiving coupler 3 has at least one inductor 6 between it and the load 5, and the transmitting coupler 2 and the receiving coupler 3 may be configured to resonate with each other in an electric field.

[0057] As a result, the reflection of high-frequency power is suppressed due to the effect of electric field resonance, improving the efficiency of wireless power transmission.

[0058] In the wireless power transmission system 1, the first electrode 21, the second electrode 22, the third electrode 31, and the fourth electrode 32 may have a flat plate shape.

[0059] This creates capacitance between opposing electrodes, improving the efficiency of wireless power transmission.

[0060] In the wireless power transmission system 1, the planar projected areas of the third electrode 31 and the fourth electrode 32 may be the same as or smaller than the planar projected area of ​​the first electrode 21.

[0061] As a result, even if the positions of the third electrode 31 and the fourth electrode 32 are misaligned, the change in capacitance between the first electrode 21 and the third electrode 31 is suppressed, and the degree of freedom in positioning the power receiving coupler 3 relative to the power transmitting coupler 2 is increased.

[0062] In the wireless power transmission system 1, the first electrode 21 and the second electrode 22 may be arranged on the same plane.

[0063] This allows the power transmission coupler 2 to be made thin.

[0064] In the wireless power transmission system 1, the second electrode 22 may be formed by partially cutting out a portion of it, and the first electrode 21 may be positioned in the cut-out portion.

[0065] This reduces the physical proportion of the second electrode 22 in the power transmission coupler 2 in the wireless power transmission system 1, thereby enabling miniaturization of the power transmission coupler 2.

[0066] The plane on which the first electrode 21 is placed and the plane on which the second electrode 22 is placed do not have to be parallel.

[0067] This eliminates the need to configure the first electrode 21 and the second electrode 22 to lie strictly on the same plane, increasing design flexibility.

[0068] In the wireless power transmission system 1, the third electrode 31 and the fourth electrode 32 may be similar in shape.

[0069] This makes it easier to align the third electrode 31 and the fourth electrode 32 to face each other, improving the design flexibility of the power receiving coupler 3.

[0070] In the wireless power transmission system 1, at least one of the power transmitting coupler 2 and the power receiving coupler 3 may be covered with a grounded electrode.

[0071] This makes it possible to suppress the leakage of unnecessary electric fields from the power transmission coupler 2 or the power receiving coupler 3 to the outside of the wireless power transmission system 1.

[0072] In the wireless power transmission system 1, an insulating coating 8 may be formed on one surface of the first electrode 21 and the second electrode 22, or on one surface of the third electrode 31.

[0073] This prevents short circuits even if the first electrode 21 and the third electrode 31, or the second electrode 22 and the third electrode 31, come into contact under unforeseen circumstances.

[0074] The wireless power transmission system 1 wirelessly transmits power from a power source 4 to a first load 5a and a second load 5b via a power transmission coupler 2 and a power reception coupler 3, wherein the power transmission coupler 2 has a first electrode 21 and a second electrode 22 connected to two terminals of the power source 4, and the power reception coupler 3 has a third electrode 31 and a fourth electrode 32 connected to two terminals of the first load 5a, and a fifth electrode 33 and a sixth electrode 34 connected to two terminals of the second load 5b, respectively. A third electrode 31 is positioned between electrode 21 and fourth electrode 32. When the first electrode 21, third electrode 31, and fourth electrode 32 are projected in a direction that causes them to overlap, a second electrode 22 is positioned at a location that does not overlap with the area where the first electrode 21, third electrode 31, and fourth electrode 32 are projected. A fifth electrode 33 is positioned between the second electrode 22 and sixth electrode 34. When the second electrode 22, fifth electrode 33, and sixth electrode 34 are projected in a direction that causes them to overlap, a first electrode 21 is positioned at a location that does not overlap with the area where the second electrode 22, fifth electrode 33, and sixth electrode 34 are projected.

[0075] This provides a wireless power transmission system 1 that achieves both freedom of position and rotation for the power receiving coupler 3 and high power transmission efficiency. Furthermore, the wireless power transmission system 1 can supply power to multiple loads 5 with a single power source 4, eliminating the need to provide multiple power sources 4 for multiple loads 5 and reducing the number of power sources 4.

[0076] This disclosure allows for various embodiments and modifications without departing from the broad spirit and scope of the present invention. For example, although the electrode shape is described above as being square, the shape is not limited to a square, and may be a polygon with pentagons or more, or a circle, etc. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of the present invention. In other words, the scope of the present invention is indicated not by the embodiments, but by the claims. Various modifications made within the scope of the claims and the equivalent significance of the disclosure are considered to be within the scope of this invention. [Explanation of Symbols]

[0077] 1. Wireless Power Transmission System 2 Power transmission coupler 3. Power receiving coupler 4 Power supply 5 load 5a 1st load 5b 2nd load 6a First Inductor 6b Second Inductor 7 Shield Case 8. Insulating coating 8a First insulating coating 8b Second insulating coating 21 1st electrode 22 2nd electrode 23 Guard electrode 31 3rd electrode 32 4th electrode 33 5th electrode 34 6th electrode

Claims

1. A wireless power transmission system that wirelessly transmits power from a power source to a load via a power transmission coupler and a power reception coupler, The power transmission coupler has a first electrode and a second electrode, each connected to two terminals of the power supply. The power receiving coupler has a third electrode and a fourth electrode, which are connected to the two terminals of the load, respectively. The third electrode is positioned between the first electrode and the fourth electrode. When the first electrode, the third electrode, and the fourth electrode are projected in a direction that overlaps them, the second electrode is positioned at a location that does not overlap with the area where the first electrode, the third electrode, and the fourth electrode are projected. Wireless power transmission system.

2. The power transmission coupler has at least one inductor between it and the power supply, The power receiving coupler has at least one inductor between it and the load, The power transmission coupler and the power reception coupler resonate in an electric field. The wireless power transmission system according to claim 1.

3. The first electrode, the second electrode, the third electrode, and the fourth electrode have a flat plate shape. The wireless power transmission system according to claim 1 or claim 2.

4. The planar projected areas of the third electrode and the fourth electrode are the same as or smaller than the planar projected area of ​​the first electrode. The wireless power transmission system according to claim 1 or claim 2.

5. The first electrode and the second electrode are arranged on the same plane. The wireless power transmission system according to claim 3.

6. The second electrode is constructed by partially cutting out a portion of it. The first electrode is positioned in the die-cut portion. The wireless power transmission system according to claim 1 or 2.

7. The third electrode and the fourth electrode are similar in shape. The wireless power transmission system according to claim 1 or claim 2.

8. At least one of the power transmission coupler and the power reception coupler is covered with a grounded electrode. The wireless power transmission system according to claim 1 or claim 2.

9. An insulating coating is formed on one surface of the first electrode and the second electrode, or on one surface of the third electrode. The wireless power transmission system according to claim 1 or claim 2.

10. A wireless power transmission system that wirelessly transmits power from a power source to a first load and a second load via a power transmission coupler and a power reception coupler, The power transmission coupler has a first electrode and a second electrode, each connected to two terminals of the power supply. The power receiving coupler has at least a third electrode connected to two terminals of the first load, a fourth electrode, a fifth electrode connected to two terminals of the second load, and a sixth electrode. The third electrode is positioned between the first electrode and the fourth electrode. When the first electrode, the third electrode, and the fourth electrode are projected in a direction that overlaps, the second electrode is positioned in a location that does not overlap with the area where the first electrode, the third electrode, and the fourth electrode are projected. The fifth electrode is positioned between the second electrode and the sixth electrode. When the second electrode, the fifth electrode, and the sixth electrode are projected in a direction in which they overlap, the first electrode is positioned at a location that does not overlap with the area where the second electrode, the fifth electrode, and the sixth electrode are projected. Wireless power transmission system.

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