Electric field type wireless power transmission coupler and electric field type wireless power transmission system

Abstract

To provide an electric field type wireless power transmission coupler 3 capable of suppressing reduction in transmission efficiency even when impedance of a load changes.SOLUTION: An electric field type wireless power transmission coupler comprises: a first power transmission side transmission line 101, a second power transmission side transmission line 102, a first power reception side transmission line 201, and a second power reception side transmission line 202; a power transmission side capacitor C12 connecting the pair of power transmission side transmission lines; a power reception side capacitor C22 connecting the pair of power reception side transmission lines; a first coupling part Cm1 at which capacitance is formed by a first power transmission side electrode 11 and a first power reception side electrode 21; and a second coupling part Cm2 at which capacitance is formed by a second power transmission side electrode 12 and a second power reception side electrode 22. The coupler is configured so that any of a representative value calculated on the basis of a capacitance value of the first coupling part Cm1 and a capacitance value of the second coupling part Cm2, a capacitance value of the power transmission side capacitor C12, and a capacitance value of the power reception side capacitor C22 is taken as a reference value and differences between the reference value and the other values are within 10% of the reference value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric field type wireless power transmission coupler and an electric field type wireless power transmission system. [Background technology]

[0002] With the spread of mobile phones and electric vehicles, there has been active development of electric field type wireless power transmission systems that supply power wirelessly. A technology has been proposed that transmits power wirelessly through an electric field using a coupler consisting of a power transmitting electrode and a power receiving electrode. Patent Document 1 describes this type of technology. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] :Patent No. 5590237 Summary of the Invention [Problem to be solved by the invention]

[0004] When the load impedance changes, for example, due to a change in power consumption, a reactance component is generated in the power supply output. This causes impedance mismatch and results in a load with a poor power factor from the power supply's perspective, which requires more power distribution or reduces transmission efficiency.

[0005] An object of the present invention is to provide an electric field type wireless power transmission coupler and an electric field type wireless power transmission system in which a decrease in transmission efficiency is suppressed even when the impedance of the load changes. [Means for solving the problem]

[0006] The electric field type wireless power transmission coupler according to the present invention includes a first power transmitting side transmission line, a second power transmitting side transmission line, a first power receiving side transmission line, and a second power receiving side transmission line, a power transmitting side capacitor connecting the first power transmitting side transmission line and the second power transmitting side transmission line, a power receiving side capacitor connecting the first power receiving side transmission line and the second power receiving side transmission line, a first power transmitting side electrode, a second power transmitting side electrode, a first power receiving side electrode, and a second power receiving side electrode, and forms a power transmitting side floating capacitance due to the formation of an electric field between the first power transmitting side electrode and the second power transmitting side electrode, and forms a power receiving side floating capacitance due to the formation of an electric field between the first power receiving side electrode and the second power receiving side electrode. the coupler has a first coupling unit that forms a capacitance between the first power transmitting side electrode and the first power receiving side electrode, and a second coupling unit that forms a capacitance between the second power transmitting side electrode and the second power receiving side electrode, and is configured so that one of a representative value calculated based on the capacitance value of the first coupling unit and the capacitance value of the second coupling unit, the sum of the capacitance value of the power transmitting side capacitor and the capacitance value of the stray capacitance on the power transmitting side, and the sum of the capacitance value of the power receiving side capacitor and the capacitance value of the stray capacitance on the power receiving side is used as a reference value, and the difference between the other two values ​​and the reference value is within ±10% of the reference value. Effect of the Invention

[0007] According to the present invention, it is possible to provide an electric field type wireless power transmission coupler and an electric field type wireless power transmission system in which a decrease in transmission efficiency is suppressed even when the impedance of the load changes. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a circuit configuration of an electric field type wireless power transmission coupler and an electric field type wireless power transmission system according to an embodiment of the present invention. [Diagram 2] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 50 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is the same as the capacitance (reference value) of the coupling section). [Diagram 3]1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 25 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is the same as the capacitance (reference value) of the coupling section). [Figure 4] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 100 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is the same as the capacitance (reference value) of the coupling section). [Diagram 5] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 100 ohms, power source impedance: 10 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is the same as the capacitance (reference value) of the coupling section). [Figure 6] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 50 ohms, power source impedance: 10 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is the same as the capacitance (reference value) of the coupling section). [Figure 7] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 25 ohms, power source impedance: 10 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is the same as the capacitance (reference value) of the coupling section). [Figure 8] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 50 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 5% larger than the capacitance (reference value) of the coupling section). [Figure 9]1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 25 ohms, power source impedance: 50 ohms, the capacitance of the power transmitting side capacitor and the power receiving side capacitor is 5% larger than the capacitance (reference value) of the coupling unit). [Figure 10] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 100 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 5% larger than the capacitance (reference value) of the coupling unit). [Figure 11] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 50 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 5% smaller than the capacitance (reference value) of the coupling section). [Figure 12] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 25 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 5% smaller than the capacitance (reference value) of the coupling section). [Figure 13] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 100 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 5% smaller than the capacitance (reference value) of the coupling unit). [Figure 14] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 50 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 10% larger than the capacitance (reference value) of the coupling section). [Figure 15]1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 25 ohms, power source impedance: 50 ohms, the capacitance of the power transmitting side capacitor and the power receiving side capacitor is 10% larger than the capacitance (reference value) of the coupling unit). [Figure 16] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 100 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 10% larger than the capacitance (reference value) of the coupling section). [Figure 17] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 50 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 10% smaller than the capacitance (reference value) of the coupling section). [Figure 18] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 25 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 10% smaller than the capacitance (reference value) of the coupling section). [Figure 19] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 100 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 10% smaller than the capacitance (reference value) of the coupling section). [Figure 20] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 50 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 20% larger than the capacitance (reference value) of the coupling section). [Figure 21]1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 25 ohms, power source impedance: 50 ohms, the capacitance of the power transmitting side capacitor and the power receiving side capacitor is 20% larger than the capacitance (reference value) of the coupling unit). [Figure 22] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 100 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 20% larger than the capacitance (reference value) of the coupling section). [Diagram 23] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 50 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 20% smaller than the capacitance (reference value) of the coupling section). [Figure 24] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 25 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 20% smaller than the capacitance (reference value) of the coupling section). [Diagram 25] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to one embodiment of the present invention (load impedance: 100 ohms, power source impedance: 50 ohms, the capacitance of the transmitting side capacitor and the receiving side capacitor is 20% smaller than the capacitance (reference value) of the coupling section). [Figure 26] 1 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to Comparative Example 1 (load impedance: 50 ohms, power source impedance: 50 ohms). [Figure 27] 11 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to Comparative Example 2 (load impedance: 25 ohms, power source impedance: 50 ohms). [Figure 28]13 is a Smith chart showing a transmission state of an electric field type wireless power transmission system according to Comparative Example 3 (load impedance: 100 ohms, power source impedance: 50 ohms). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an electric field type wireless power transmission coupler and an electric field type wireless power transmission system according to embodiments of the present invention will be described with reference to the drawings. In addition, in each drawing, the same components are given the same reference numerals.

[0010] Hereinafter, an electric field type wireless power transmission coupler 3 and an electric field type wireless power transmission system S according to an embodiment will be described with reference to FIGS.

[0011] 1, an electric-field-type wireless power transmission system S according to one embodiment of the present invention includes a wireless power transmitting device 1 and a wireless power receiving device 2. The wireless power transmitting device 1 includes a power transmitting side coupler body 301, a power transmitting side reactance adjustment circuit 31, and a power source 4. The wireless power receiving device 2 includes a power receiving side coupler body 302, a power receiving side reactance adjustment circuit 32, and a load 5.

[0012] The power transmitting side coupler body 301 has a first power transmitting side electrode 11 and a second power transmitting side electrode 12. The power receiving side coupler body 302 has a first power receiving side electrode 21 and a second power receiving side electrode 22. The power transmitting side coupler body 301 and the power receiving side coupler body 302 form a coupler 300.

[0013] The first power transmitting electrode 11 and the first power receiving electrode 21 form a capacitance to constitute a first coupling section Cm1, and the second power transmitting electrode 12 and the second power receiving electrode 22 form a capacitance to constitute a second coupling section Cm2.

[0014] A floating capacitance C11 on the power transmitting side is formed due to the formation of an electric field between the first power transmitting side electrode 11 and the second power transmitting side electrode 12, and a floating capacitance C21 on the power receiving side is formed due to the formation of an electric field between the first power receiving side electrode 21 and the second power receiving side electrode 22.

[0015] The electric field type wireless power transmission coupler 3 includes a first power transmitting side transmission line 101, a second power transmitting side transmission line 102, a first power receiving side transmission line 201, a second power receiving side transmission line 202, a coupler 300, a power transmitting side capacitor C12 connecting the first power transmitting side transmission line 101 and the second power transmitting side transmission line 102, and a power receiving side capacitor C22 connecting the first power receiving side transmission line 201 and the second power receiving side transmission line 202.

[0016] The first power transmitter electrode 11, the second power transmitter electrode 12, the first power receiver electrode 21, and the second power receiver electrode 22 are preferably, but are not limited to, flat plate electrodes.

[0017] The first power transmitting side electrode 11 is connected to a first output end 401 of the power source 4 via a first power transmitting side transmission line 101 and a first power transmitting side coil L11 in this order. The second power transmitting side electrode 12 is connected to a second output end 402 of the power source 4 via a second power transmitting side transmission line 102 and a second power transmitting side coil L12 in this order. The first power transmitting side transmission line 101 and the second power transmitting side transmission line 102 are connected to each other via a power transmitting side capacitor C12. The first power transmitting side coil L11, the second power transmitting side coil L12, and the power transmitting side capacitor C12 form a power transmitting side reactance adjustment circuit 31.

[0018] The first power receiving side electrode 21 is connected to a first input end 501 of the load 5 via a first power receiving side transmission line 201 and a first power receiving side coil L21 in this order. The second power receiving side electrode 22 is connected to a second input end 502 of the load 5 via a second power receiving side transmission line 202 and a second power receiving side coil L22 in this order. The first power receiving side transmission line 201 and the second power receiving side transmission line 202 are connected via a power receiving side capacitor C22. The first power receiving side coil L21, the second power receiving side coil L22, and the power receiving side capacitor C22 form a power receiving side reactance adjustment circuit 32.

[0019] As described above, the capacitive coupling type wireless power transmission method in which a coil and a capacitor are provided is called an electric field method.

[0020] An AC power is transmitted from the power source 4 shown in FIG. 1. When a positive voltage is transmitted and a positive charge is accumulated in the first power transmitting electrode 11 from the power source, a negative charge is induced in the first power receiving electrode 21 through the first coupling unit Cm1. Then, the negative voltage is transmitted to the power receiving side. When a negative voltage is transmitted and a negative charge is accumulated in the first power transmitting electrode 11 from the power source, a positive charge is induced in the first power receiving electrode 21 through the first coupling unit Cm1. Then, the positive voltage is transmitted to the power receiving side. Then, AC power is transmitted to the power receiving side. Similarly, AC power is transmitted between the second power transmitting electrode 12 and the second power receiving electrode 22. As described above, the power from the power transmitting side is transmitted to the power receiving device through the first coupling unit Cm1 and the second coupling unit Cm2. Then, the power is supplied to the second load 52.

[0021] The load 5 is, for example, a storage battery, which is used in industrial equipment, portable electronic devices, etc. Examples of the industrial equipment include electric vehicles, and examples of the portable electronic devices include laptop computers, smartphones, and portable music players.

[0022] The capacitance value of the transmitting side stray capacitance C11 is c11, the capacitance value of the transmitting side capacitor C12 is c12, the capacitance value of the first coupling section Cm1 is cm1, the capacitance value of the second coupling section Cm2 is cm2, the capacitance value of the receiving side stray capacitance C21 is c21, and the capacitance value of the receiving side capacitor C22 is c22.

[0023] In the electric field type wireless power transmission coupler 3 and the electric field type wireless power transmission system S according to the first embodiment of the present invention, the formula (1) is satisfied. However, as will be described later, it is not necessary that the equality is completely satisfied. c11+c12 = (cm1+cm2) / 2 =c21+c22 (Equation 1)

[0024] Moreover, it is preferable that formula (2) be satisfied in the electric field type wireless power transmission coupler 3 and the electric field type wireless power transmission system S. However, as will be described later, it is not necessary that the equality be satisfied completely. cm1=cm2 (formula 2) In this case, formula (3) is satisfied in the electric field type wireless power transmission coupler 3 and the electric field type wireless power transmission system S. However, as will be described later, it is not necessary for the equality to be completely satisfied. c11+c12=cm1=cm2=c21+c22 (Formula 3)

[0025] The inductance of the first power transmitting side coil L11 and the second power transmitting side coil L12 in the power transmitting side reactance adjustment circuit 31 is optimized, and the inductance of the first power receiving side coil L21 and the second power receiving side coil L22 in the power receiving side reactance adjustment circuit 32 is optimized. Then, in the electric field type wireless power transmission system S, the impedance of the power source 4 and the impedance of the electric field type wireless power transmission system S seen from the power source 4 match.

[0026] 2 to 7 show, in Smith charts, how power is transferred when Equations 1, 2, and 3 are strictly satisfied.

[0027] 2 to 4 show the impedance behavior when the initial impedance of the load 5 is 50 ohms and the impedance of the power source 4 is 50 ohms.

[0028] Fig. 2 shows the impedance state when the impedance of the load 5 is 50 ohms and the impedance of the power supply is 50 ohms. The plotted points in Fig. 2 show the impedance state at the first input end 501 of the load 5 in Fig. 1, at locations a to d, and at the first output end 401 of the power supply 4. a represents the power supply side of the first power receiving side coil L21, b represents the load 5 side of the first power receiving side electrode 21, c represents the power supply side of the first power transmitting side electrode 11, and d represents the load 5 side of the first power transmitting side coil L11.

[0029] At the first input terminal 501 of the load 5, the load impedance is 50 ohms, so the state is plotted in the center of the Smith chart. The first receiving coil L21 generates a reactance, and at point a in FIG. 1, the point moves significantly to the lower right on the Smith chart (point a) as shown in FIG. 2. Furthermore, due to the influence of the receiving capacitor C22 and the receiving side floating capacitance C21, the point moves to the upper right (point b). Next, due to the influence of the first coupling unit Cm1, the point moves upward (point c), and due to the influence of the transmitting side floating capacitance C11 and the transmitting side capacitor C12, the point moves to the upper left (point d), and due to the influence of the first transmitting coil L11, the impedance of the power source moves to match 50 ohms.

[0030] That is, the impedance of the power source and the impedance of the electric field type wireless power transmission system seen from the power source are equal to 50 ohms.

[0031] The transmission efficiency can be estimated by the power factor of the output at the first output terminal 401 of the power source 4. The power factor is the cosine (cos θ) of the phase difference θ between the voltage and current in the transmitted power. When the power factor is 1, the amount of power that can be effectively used is maximized. When the power factor is small, the voltage must be increased to supply the same power, and the transmission efficiency decreases. Below, efficiency will be discussed using the power factor as appropriate.

[0032] As shown in FIG. 2, there is no imaginary part at the first output 401 of the power supply 4, the power factor is unity, and maximum efficiency is achieved.

[0033] FIG. 3 shows the effect of reducing the impedance of the load 5 to 25 ohms. Since the load 5 is 25 ohms, the load 5 is plotted at 0.5 on the Smith chart. Even though the load 5 has been reduced, the plot point at the first output 401 of the power supply 4 is still on the horizontal axis of the Smith chart. That is, no reactance or imaginary part is present at the first output 401 of the power supply 4. As shown in FIG. 3, the power factor at the first output 401 of the power supply 4 is unity, and maximum efficiency is achieved.

[0034] FIG. 4 shows the effect of increasing the impedance of the load 5 to 100 ohms. Since the load 5 is 100 ohms, the impedance of the first input 501 of the load 5 is plotted at position 2 on the Smith chart. Even though the load 5 has been reduced, the plot point at the first output 401 of the power supply 4 remains on the horizontal axis of the Smith chart. That is, no reactance or imaginary part is generated at the first output 401 of the power supply 4. As shown in FIG. 4, the power factor at the first output 401 of the power supply 4 is unity, and maximum efficiency is achieved.

[0035] 5 to 7 show, in a Smith chart, impedance behavior when the impedance of the load 5 changes from 100 ohms to 50 ohms and to 25 ohms when the initial impedance of the load 5 is 100 ohms and the impedance of the power supply is 10 ohms.

[0036] Fig. 5 shows the impedance state when the impedance of the load 5 is 100 ohms and the impedance of the power supply is 10 ohms. The plotted points in Fig. 5 show the impedance at the first input end 501 of the load 5 in Fig. 1, at locations a to d, and at the first output end 401 of the power supply 4. a represents the power supply side of the first power receiving side coil L21, b represents the load 5 side of the first power receiving side electrode 21, c represents the power supply side of the first power transmitting side electrode 11, and d represents the load 5 side of the first power transmitting side coil L11.

[0037] At the first input terminal 501 of the load 5, the load impedance is 100 ohms, so the state is plotted at 2 (i.e., twice 50 ohms) on the Smith chart. The first receiving coil L21 generates a reactance, and at point a in FIG. 5, the point moves to the upper right on the Smith chart (point a) as shown in FIG. 5. Furthermore, the point moves downward (point b) due to the influence of the receiving capacitor C22 and the receiving side floating capacitance C21. Next, the point moves to the right (point c) due to the influence of the first coupling unit Cm1, and moves to the lower left (d) due to the influence of the transmitting side floating capacitance C11 and the transmitting side capacitor C12. Since the inductance of the first transmitting coil L11 is adjusted, the impedance of the power source 4 moves to match 10 ohms.

[0038] That is, the impedance of the power source 4 and the impedance of the electric field type wireless power transmission system S seen from the power source 4 are equal to each other and are 10 ohms. As shown in Fig. 5, there is no imaginary part at the first output end 401 of the power source 4, the power factor is 1, and the maximum efficiency is realized.

[0039] FIG. 6 shows the effect when the impedance of the load 5 is reduced to 50 ohms. Since the impedance of the load 5 is 50 ohms, the impedance of the first input 501 of the load 5 is plotted at position 1 on the Smith chart. Even though the impedance of the load 5 has been reduced, the plot point of the impedance at the first output 401 of the power supply 4 is located on the horizontal axis of the Smith chart. That is, no reactance or imaginary part is generated at the first output 401 of the power supply 4. As shown in FIG. 6, the power factor at the first output 401 of the power supply 4 is 1, and maximum efficiency is achieved.

[0040] FIG. 7 shows the effect of further reducing the impedance of the load 5 to 25 ohms. Since the impedance of the load 5 is 25 ohms, the impedance at the first input 501 of the load 5 is plotted at 0.5 on the Smith chart. Even though the impedance of the load 5 has been reduced, the plot point of the impedance at the first output 401 of the power supply 4 is located on the horizontal axis of the Smith chart. That is, no reactance or imaginary part is generated at the first output 401 of the power supply 4. As shown in FIG. 7, the power factor at the first output 401 of the power supply 4 is 1, and maximum efficiency is achieved.

[0041] In formulas (1), (2), and (3), they are simply connected with an equal sign, but they do not need to match perfectly, and it is preferable that the difference is within ±10%. Generally, a power factor of 0.9 or more is required, and this condition is satisfied. This will be explained using Figures 8 to 25.

[0042] Equation 1 is recited. c11+c12 = (cm1+cm2) / 2 =c21+c22 (Equation 1) We will verify the case where the values ​​of c11, c12, c21, c22, cm1, and cm2 vary and the equality of Equation 1 does not hold perfectly. Let c11+c12=c21+c22, and vary the value of c11+c12 by 5% to 20% compared to the value of (cm1+cm2) / 2.

[0043] When a system is constructed so that formula 1 is satisfied, this variation corresponds to, for example, variation in the manufacturing process, variation between manufacturers, or a deviation tolerance range as a standard condition.

[0044] Fig. 8 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 50 ohms, the power supply impedance is 50 ohms, and the value of c11+c12 is 5% greater than (cm1+cm2) / 2. Fig. 9 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 25 ohms under the conditions of Fig. 8. Fig. 10 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 100 ohms under the conditions of Fig. 8.

[0045] When the impedance of the load 5 is 50 ohms, the power factor is 0.9998, as shown in Figure 8. When the impedance of the load 5 is 25 ohms, the power factor is 0.9865, as shown in Figure 9. When the impedance of the load 5 is 100 ohms, the power factor is 0.977, as shown in Figure 10.

[0046] Fig. 11 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 50 ohms, the power supply impedance is 50 ohms, and the value of c11+c12 is 5% smaller than (cm1+cm2) / 2. Fig. 12 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 25 ohms under the conditions of Fig. 11. Fig. 13 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 100 ohms under the conditions of Fig. 11.

[0047] When the impedance of the load 5 is 50 ohms, the power factor is 0.9999, as shown in Figure 11. When the impedance of the load 5 is 25 ohms, the power factor is 0.9802, as shown in Figure 12. When the impedance of the load 5 is 100 ohms, the power factor is 0.9874, as shown in Figure 13.

[0048] Fig. 14 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 50 ohms, the power supply impedance is 50 ohms, and the value of c11+c12 is 10% greater than (cm1+cm2) / 2. Fig. 15 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 25 ohms under the conditions of Fig. 14. Fig. 16 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 100 ohms under the conditions of Fig. 14.

[0049] When the impedance of the load 5 is 50 ohms, the power factor is 0.9957, as shown in Figure 14. When the impedance of the load 5 is 25 ohms, the power factor is 0.9645, as shown in Figure 15. When the impedance of the load 5 is 100 ohms, the power factor is 0.8925, as shown in Figure 16.

[0050] Fig. 17 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 50 ohms, the power supply impedance is 50 ohms, and the value of c11+c12 is 10% smaller than (cm1+cm2) / 2. Fig. 18 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 25 ohms under the conditions of Fig. 17. Fig. 19 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 100 ohms under the conditions of Fig. 17.

[0051] When the impedance of the load 5 is 50 ohms, the power factor is 0.9983 as shown in Figure 17. When the impedance of the load 5 is 25 ohms, the power factor is 0.9223 as shown in Figure 18. When the impedance of the load 5 is 100 ohms, the power factor is 0.9650 as shown in Figure 19.

[0052] Fig. 20 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 50 ohms, the power supply impedance is 50 ohms, and the value of c11+c12 is 20% greater than (cm1+cm2) / 2. Fig. 21 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 25 ohms under the conditions of Fig. 20. Fig. 22 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 100 ohms under the conditions of Fig. 20.

[0053] When the impedance of the load 5 is 50 ohms, the power factor is 0.9127, as shown in Figure 20. When the impedance of the load 5 is 25 ohms, the power factor is 0.9781, as shown in Figure 21. When the impedance of the load 5 is 100 ohms, the power factor is 0.6002, as shown in Figure 22.

[0054] Fig. 23 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 50 ohms, the power supply impedance is 50 ohms, and the value of c11+c12 is 20% smaller than (cm1+cm2) / 2. Fig. 24 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 25 ohms under the conditions of Fig. 23. Fig. 25 shows the impedance behavior in the Smith chart when the impedance of the load 5 is 100 ohms under the conditions of Fig. 23.

[0055] When the impedance of the load 5 is 50 ohms, the power factor is 0.9843 as shown in Figure 23. When the impedance of the load 5 is 25 ohms, the power factor is 0.7704 as shown in Figure 24. When the impedance of the load 5 is 100 ohms, the power factor is 0.9326 as shown in Figure 25.

[0056] Generally, a power factor of 0.9 or more is required. In the above example, when the value of c11+c12 differs from (cm1+cm2) / 2 by 20% and the impedance of the load 5 varies between 25 ohms and 100 ohms, the combination of conditions in which the power factor falls below 0.9 is included. From this, it is preferable that the value of c11+c12 is within ±10% of (cm1+cm2) / 2, and the equal sign in formula 1 means that it is within ±10%.

[0057] (Comparative Example) Comparative examples are shown in Figures 26 to 28. The case where formula (1) is not satisfied and the capacitance value deviates from the equality by about 30% is shown.

[0058] The initial impedance of the load 5 is 50 ohms, and the impedance of the power source is 50 ohms. The power transmitting side reactance adjustment circuit 31 and the power receiving side reactance adjustment circuit 32 are adjusted so that the impedance of the power source 4 and the impedance of the electric field type wireless power transmission system S seen from the power source 4 match and become 50 ohms.

[0059] Incidentally, in the transmission states shown in Figures 8, 11, 14, 17, 20, and 23 in the embodiment of the present invention, even though the impedance of the load 5 is 50 ohms, the power factor is close to 1 but is not 1. This phenomenon occurs because the conditions are intentionally removed from the optimized state. It is important to note that in the comparative example, optimization is performed when the impedance of the load 5 is 50 ohms, and the power factor is 1.

[0060] In the comparative example, the impedance state is shown on a Smith chart when the impedance of the load 5 changes from an initial value of 50 ohms to 25 ohms or 100 ohms.

[0061] Fig. 26 shows the impedance state when the impedance of the load 5 is 50 ohms. The plotted points in Fig. 26 show the impedance at the first input end 501 of the load 5 in Fig. 1, at locations a to d, and at the first output end 401 of the power source 4. a represents the power source side of the first power receiving side coil L21, b represents the load 5 side of the first power receiving side electrode 21, c represents the power source side of the first power transmitting side electrode 11, and d represents the load 5 side of the first power transmitting side coil L11.

[0062] At the first input terminal 501 of the load 5, the load impedance is 50 ohms, so the impedance is plotted at 1 on the Smith chart. The first power receiving coil L21 generates a reactance, and at point a in FIG. 5, the impedance moves to the lower right on the Smith chart (point a) as shown in FIG. 26. Furthermore, due to the influence of the power receiving capacitor C22 and the power receiving side floating capacitance C21, the impedance moves to the upper right (point b). Next, due to the influence of the first coupling unit Cm1, the impedance moves to the upper left (point c), and due to the influence of the power transmitting side floating capacitance C11 and the power transmitting side capacitor C12, the impedance moves to the upper left (d). Since the inductance of the first power transmitting coil L11 is adjusted, the impedance moves to match 50 ohms, which is the impedance of the power source.

[0063] That is, the impedance of the power source and the impedance of the electric field type wireless power transmission system seen from the power source are equal to 50 ohms.

[0064] There is no significant difference between the plots shown in Fig. 5 and the plots shown in Fig. 26. This is because the transmitting-side reactance adjustment circuit 31 and the receiving-side reactance adjustment circuit 32 shown in Fig. 1 are adjusted so that the impedances at the first output terminal 401 of the power source 4 match in either case.

[0065] FIG. 27 shows the effect when the impedance of the load 5 is reduced to 25 ohms. Since the impedance of the load 5 is 25 ohms, the impedance of the load 5 is plotted at 0.5 on the Smith chart. A reactance occurs due to the first receiving coil L21, and at point a in FIG. 27, the impedance moves to the upper right on the Smith chart as shown in FIG. 27 (point a). Furthermore, due to the influence of the receiving capacitor C22 and the receiving side stray capacitance C21, the impedance moves to the lower right (point b). Next, due to the influence of the first coupling unit Cm1, the impedance moves to the lower left (point c), due to the influence of the transmitting side stray capacitance C11 and the transmitting side capacitor C12, the impedance moves to the lower left (d), and due to the influence of the first transmitting side coil L11, the impedance moves to the upper left.

[0066] Unlike Fig. 6, the plot point of the impedance at the first output terminal 401 of the power supply 4 is located significantly above the horizontal axis of the Smith chart. That is, reactance or an imaginary part occurs at the first output terminal 401 of the power supply 4. That is, a deterioration in the power factor occurs. The power factor is 0.8226.

[0067] FIG. 28 shows the effect when the impedance of the load 5 is increased to 100 ohms. Since the load 5 is 100 ohms, the impedance of the load 5 is plotted at position 2 on the Smith chart. A reactance occurs due to the first receiving side coil L21, and at point a in FIG. 28, the impedance moves to the upper right on the Smith chart (point a). Furthermore, due to the influence of the receiving side capacitor C22 and the receiving side stray capacitance C21, it moves to the lower right (point b). Next, it moves to the lower right due to the influence of the first coupling unit Cm1 (point c), moves to the lower left due to the influence of the transmitting side stray capacitance C11 and the transmitting side capacitor C12 (d), and moves to the left due to the influence of the first transmitting side coil L11.

[0068] Unlike Fig. 7, the plot point of the impedance at the first output terminal 401 of the power supply 4 is located significantly below the horizontal axis of the Smith chart. That is, reactance or an imaginary part occurs at the first output terminal 401 of the power supply 4. That is, a deterioration in the power factor occurs. The power factor is 0.8226.

[0069] The results of Figures 26, 27, and 28 will be summarized. When the load impedance 5 is 50 ohms, the first power transmitting coil L11, the second power transmitting coil L12, etc. are adjusted so that the impedance of the first output is 50 ohms, that is, the power factor is 1. However, despite this adjustment, when the load impedance 5 is reduced to 25 ohms or increased to 100 ohms, the power factor falls below 0.9, and the reduction in transmission efficiency is at a problematic level.

[0070] As described above, by satisfying formula (1) in the electric field type wireless power transmission system, deterioration of the power factor due to fluctuations in the load impedance is suppressed, and thus high transmission efficiency is maintained even if the impedance of the load 5 fluctuates.

[0071] The stray capacitance C11 on the power transmitting side and the stray capacitance C21 on the power receiving side may be smaller than 1 / 10 of the first coupling part Cm1 or the second coupling part Cm2 depending on the system. In such a case, the capacitance value c11 of the stray capacitance C11 on the power transmitting side and the capacitance value c21 of the stray capacitance C21 on the power receiving side can be ignored in formula (1).

[0072] The electric field type wireless power transmission coupler according to the embodiment described above provides the following advantages.

[0073] The electric field type wireless power transmission coupler 3 has a first power transmitting side transmission line 101, a second power transmitting side transmission line 102, a first power receiving side transmission line 201 and a second power receiving side transmission line 202, a power transmitting side capacitor C12 connecting the first power transmitting side transmission line 101 and the second power transmitting side transmission line 102, a power receiving side capacitor C22 connecting the first power receiving side transmission line 201 and the second power receiving side transmission line 202, a first power transmitting side electrode 11, a second power transmitting side electrode 12, a first power receiving side electrode 21 and a second power receiving side electrode 22, and forms a power transmitting side stray capacitance C11 due to the formation of an electric field between the first power transmitting side electrode 11 and the second power transmitting side electrode 12, and forms a power receiving side stray capacitance C21 due to the formation of an electric field between the first power receiving side electrode 21 and the second power receiving side electrode 22. the coupler 3 having a first coupling unit Cm1 that forms a capacitance between the power transmitting side electrode 11 and the first power receiving side electrode 21, and a second coupling unit Cm2 that forms a capacitance between the second power transmitting side electrode 12 and the second power receiving side electrode 22, and is configured so that one of the following is set as a reference value: a representative value indicating the size of the first coupling unit Cm1 and the second coupling unit Cm2, the sum of the capacitance value of the power transmitting side capacitor C12 and the capacitance value of the power transmitting side stray capacitance C11, and the sum of the capacitance value of the power receiving side capacitor C22 and the capacitance value of the power receiving side stray capacitance C21, and the difference between the other two values ​​and the reference value is within 10% of the reference value.

[0074] Even if the impedance of the load 5 varies, high transmission efficiency is maintained.

[0075] In the electric field type wireless power transmission coupler 3, a representative value calculated based on the capacitance value of the first coupling section Cm1 and the capacitance value of the second coupling section Cm2 is configured to be equal to the sum of the capacitance value of the power transmitting side capacitor C12 and the capacitance value of the power transmitting side stray capacitance C11, and the sum of the capacitance value of the power receiving side capacitor C22 and the capacitance value of the power receiving side stray capacitance C21.

[0076] Even if the impedance of the load 5 fluctuates, the decrease in the transmission efficiency is more reliably suppressed.

[0077] In the electric field type wireless power transmission coupler 3, the representative value calculated based on the capacitance value of the first coupling section Cm1 and the capacitance value of the second coupling section Cm2 is the average value of the capacitance value of the first coupling section Cm1 and the capacitance value of the second coupling section Cm2.

[0078] When the distance between the first power transmitting side electrode 11 and the first power receiving side electrode that constitute the first coupling section Cm1, and the distance between the second power transmitting side electrode 12 and the second power receiving side electrode 22 that constitute the second coupling section Cm2 vary, a decrease in transmission efficiency is suppressed.

[0079] In the electric field type wireless power transmission coupler 3, the capacitance value of the first coupling section Cm1 and the capacitance value of the second coupling section Cm2 are equal.

[0080] The first coupling unit Cm1 and the second coupling unit Cm2 are configured with the same structure. Components can be standardized. The electric field type wireless power transmission coupler 3 has a symmetrical configuration, making it easier to achieve impedance matching.

[0081] An electric field type wireless power transmission system S includes the electric field type wireless power transmission coupler 3 described above.

[0082] Even if the impedance of the load 5 varies, high transmission efficiency is maintained.

[0083] Various embodiments and modifications of the present disclosure are possible without departing from the broad spirit and scope of the present invention. The above-described embodiments are for the purpose of explaining the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the scope of the disclosure equivalent thereto are considered to be within the scope of the present invention. [Explanation of symbols]

[0084] REFERENCE SIGNS LIST 1 wireless power transmitting device, 2 wireless power receiving device, 3 electric field type wireless power transmission coupler, 4 power source, 5 load, 11 first power transmitting side electrode, 12 second power transmitting side electrode, 21 first power receiving side electrode, 22 second power receiving side electrode, 101 first power transmitting side transmission line, 102 second power transmitting side transmission line, 201 first power receiving side transmission line, 202 second power receiving side transmission line, C11 stray capacitance of power transmitting side, 300 coupler, C12 power transmitting side capacitor, C21 stray capacitance of power receiving side, C22 power receiving side capacitor, Cm1 first coupling unit, Cm2 second coupling unit, S electric field type wireless power transmission system

Claims

1. a first power transmitting side transmission line, a second power transmitting side transmission line, a first power receiving side transmission line, and a second power receiving side transmission line; a power transmission side capacitor connecting the first power transmission side transmission line and the second power transmission side transmission line; a power receiving side capacitor connecting the first power receiving side transmission line and the second power receiving side transmission line; a coupler having a first power transmitting side electrode, a second power transmitting side electrode, a first power receiving side electrode, and a second power receiving side electrode, forming a power transmitting side stray capacitance due to the formation of an electric field between the first power transmitting side electrode and the second power transmitting side electrode, forming a power receiving side stray capacitance due to the formation of an electric field between the first power receiving side electrode and the second power receiving side electrode, having a first coupling portion that forms a capacitance between the first power transmitting side electrode and the first power receiving side electrode, and a second coupling portion that forms a capacitance between the second power transmitting side electrode and the second power receiving side electrode; Equipped with a representative value indicating the magnitude of the capacitance value of the coupling section calculated based on the capacitance value of the first coupling section and the capacitance value of the second coupling section; the sum of the capacitance value of the power transmission side capacitor and the capacitance value of the power transmission side stray capacitance; the sum of the capacitance value of the power receiving side capacitor and the capacitance value of the power receiving side stray capacitance; One of the above is set as a reference value, and the difference between the other two values ​​and the reference value is within 10% of the reference value.

2. The representative value; the sum of the capacitance value of the power transmission side capacitor and the capacitance value of the power transmission side stray capacitance; the sum of the capacitance value of the power receiving side capacitor and the capacitance value of the power receiving side stray capacitance; The electric field type wireless power transmission coupler according to claim 1 , configured so that

3. 3. The electric field type wireless power transmission coupler according to claim 1, wherein the representative value is a representative value of a capacitance value of the first coupling section and a capacitance value of the second coupling section.

4. 4. The electric field type wireless power transmission coupler according to claim 1, wherein the capacitance value of the first coupling section and the capacitance value of the second coupling section are equal to each other.

5. An electric field type wireless power transmission system comprising the electric field type wireless power transmission coupler according to claim 1 .

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