JP6973781B2 - Wireless power transmission system - Google Patents

Description

The present invention relates to a wireless power transmission system. In particular, the wireless power transmission system according to the present invention has obstacles such as a metal body and an insulator inside, is surrounded by a member that reflects electromagnetic waves, and is installed in a pipe, an engine room, a factory, or the like. It relates to an electric structure for wirelessly supplying electric power to a sensor or the like and transmitting / receiving information, and an electronic device used for the electric structure.

A conventional wireless power transmission system to a remote place consists of an antenna that receives electromagnetic waves and a rectifier circuit connected to the antenna, based on the principle of rectenna. A wireless power transmission system is configured by providing an array structure in which a plurality of the antennas are arranged close to each other to expand an effective power receiving area.

As a wireless power transmission system using a rectenna, for example, Patent Document 1 and Patent Document 2 are disclosed. In Patent Document 1, a receiving means for receiving microwaves, first and second rectifying circuits for rectifying the received microwaves, and the receiving means and the first and second rectifying circuits are interposed. A rectenna with a hybrid circuit is disclosed. Further, Patent Document 2 discloses a wireless sensor system including a power supply unit that supplies power obtained by energy harvesting to a sensor and a wireless communication unit, and a rectenna that converts a received signal into electric power.

In particular, a wireless power transmission system that is entirely surrounded by a conventional electromagnetic wave reflecting member (hereinafter referred to as an electromagnetic wave reflecting member) has a poor visibility or a good visibility with obstacles such as a metal body or an insulator. However, in order to transmit power to a place adjacent to an obstacle such as a metal body or an insulator, electromagnetic waves are transmitted at the resonance frequency when the wireless power transmission system is assumed to be a waveguide resonator.

For example, Non-Patent Document 1 includes a structure completely surrounded by a metal plate, a power transmission unit and a power reception unit installed inside the structure, and resonance when the structure is assumed to be a waveguide resonator. A wireless power transmission system that transmits electromagnetic waves at a frequency is disclosed.

Japanese Unexamined Patent Publication No. 2012-23857

Japanese Unexamined Patent Publication No. 2013-137671

Ippei Takano, Daigo Furusato, Yosuke Watanabe, Masaya Tamura, "Study on Wireless Power Transmission Method Using Cavity Resonance in Confined Space," Shingaku Giho WPT2016-62, vol.116, no.452, pp.27 -30, Feb. 2017.

In such a conventional wireless power transmission system, the impedance differs depending on the power receiving unit, so it is necessary to design and mount as many matching circuits as there are power receiving units to ensure matching between power transmission and reception, and installation of the power receiving unit. Limitations were a problem.

That is, in the conventional wireless power supply system, a power receiving unit is installed in a place having an obstacle such as a metal body or an insulator with poor visibility, or a place adjacent to an obstacle such as a metal body or an insulator even if the visibility is good. Since the matching conditions between power transmission and reception change depending on the location, a matching circuit designed individually must be installed. Since a large number of terminals such as sensors installed in pipes, engine rooms, factories, etc. are placed, sensors etc. are placed in the place where they are installed in advance and the impedance between power transmission and reception is measured for each sensor. Since it is necessary to mount a matching circuit that is individually matched, it is difficult to install it in a place where impedance measurement is difficult.

The present invention has been made to solve the above problems, and is characterized in that a probe capable of varying impedance (hereinafter referred to as an impedance variable probe) is provided on an electromagnetic wave reflecting material instead of a power receiving terminal. If an LC circuit is connected to the probe, the electrical length of the probe can be changed by changing the element value of the LC. As a result, the impedance of the structure surrounded by the electromagnetic wave reflector changes according to the probe length, and matching between power transmission and reception can be achieved.

The first wireless power transmission system according to the present invention includes at least one power receiving unit, a structure completely surrounded by an electromagnetic wave reflecting member, and at least one transmitting unit installed inside the structure. The power transmission unit transmits electromagnetic waves having a resonance frequency when the main body of the equipment is assumed to be a waveguide resonator, and is connected to a reactor on the wall surface of the structure and / or inside the structure. It is characterized by having at least one variable impedance probe.

The second wireless power transmission system according to the present invention is the first wireless power transmission system according to the present invention, and the reactance element is characterized by having a function of changing the reactance value.

The third wireless power transmission system according to the present invention is the first or second wireless power transmission system according to the present invention, and the structure is partially used by an electromagnetic wave reflecting member of a different type from the others. It is characterized by being done.

The fourth wireless power transmission system according to the present invention is any one of the first to third wireless power transmission systems according to the present invention, and the electromagnetic wave reflecting member surrounding the structure is a partial region. Alternatively, it is characterized by having a through hole as a whole.

The fifth wireless power transmission system according to the present invention is the fourth wireless power transmission system according to the present invention, and the through hole has a part or all of the electromagnetic wave reflecting member having an appropriate relative magnetic permeability. It is characterized in that it is provided by periodically forming a material having.

The sixth wireless power transmission system according to the present invention is any one of the first to fifth wireless power transmission systems according to the present invention, and is composed of a metal body and / or an insulator inside the structure. When an obstacle is installed, the resonance frequency is set to a resonance frequency calculated by regarding the obstacle as a reactance element.

With the electrical configuration of the wireless power transmission system according to the present invention, impedance matching between power transmitters and receivers is ensured without designing a matching circuit for ensuring impedance matching between power transmission and reception according to the installation location of the power receiving unit. Therefore, it is possible to secure the required power reception at any location regardless of the installation location. As a result, it is possible to supply the power required for the sensor or the like without having to individually design a matching circuit according to the installation location of the power receiving unit.

It is a figure which shows the structure of the wireless power transmission system which concerns on this invention. It is a figure which shows the transmission model of the wireless power transmission system which concerns on this invention. It is a figure which shows the structure of the wireless power transmission system which concerns on this invention. It is a perspective view of the wireless power transmission system which installed the power receiver within the line of sight in the wireless power transmission system of Example 1 which concerns on this invention. It is a perspective view which shows the method of attaching a copper wire to an SMA connector. It is a perspective view of the wireless power transmission system which installed the power receiver out of sight in the wireless power transmission system of Example 1 which concerns on this invention.

The wireless power transmission system according to the present invention will be described with reference to FIG. FIG. 1 is a configuration diagram of a wireless power transmission system according to the present invention. In FIG. 1, the wireless power transmission system 1 has a structure in which at least one transmitter 2, at least one receiver 3, and an electromagnetic wave reflector 4, which is a material for reflecting electromagnetic waves, surrounds the entire surface of the wireless power transmission system 1. It consists of body 5. That is, the wireless power transmission system 1 refers to the entire structure that performs wireless power supply. At least one or more variable impedance probes 7 connected to the reactance element 6 are provided on the wall surface of the structure and / or inside the structure.

Examples of the electromagnetic wave reflecting plate 4 include metals such as copper and iron, conductive materials having a high relative magnetic permeability, and meshes and nets made of these.
Further, the reactance element 6 is, for example, an inductor or a chip inductor in which a metal is wound in a coil, an inductive element made of a variable inductor capable of mechanically displace a magnetic material to change an inductive value, or a dielectric made of a metal. It is composed of either or both of a capacitive element consisting of a sandwiched capacitor, a chip capacitor, and a varicapa diode whose capacitance value can be changed by a voltage. The impedance variable probe 7 is composed of a metal rod, a monopole shape wound in a helical shape, a loop shape wound in a coil shape, or the like.

Subsequently, this configuration will be specifically described. Since the wireless power transmission system 1 has a space shielded by the structure 5, it can be considered as a waveguide resonator. _{Therefore, in the wireless power transmission system 1, the resonance frequencies fr1 m, n, and p} obtained from the length a of the side in the x-axis direction, the length b of the side in the y-axis direction, and the length c of the side in the z-axis direction are transmitted. By setting the frequency,

前記構造体５内全体に電磁界を分布させることができる。ここで、ｖは光速、μｒは比透磁率、εｒは比誘電率、ｍ、ｎ、ｐはそれぞれ整数を示している。

The electromagnetic field can be distributed throughout the structure 5. Here, v is the speed of light, μr is the relative permeability, εr is the relative permittivity, and m, n, and p are integers.

The resonance frequency indicating the lowest frequency is called the basis resonance frequency. For example, when the wireless power transmission system 1 is represented by a rectangular parallelepiped as shown in FIG. 1 and the transmitter 2 is arranged in the z-axis direction from the center of the xy plane of the structure 5, m = 1 and n = 1. , The TE110 mode in which p = 0 indicates the ground resonance frequency. When the transmission frequency is set to the ground resonance frequency, an electromagnetic field standing wave is generated in the entire wireless power transmission system 1.

Where the amplitude of the electric field standing wave is dense, the amplitude of the magnetic field standing wave is sparse, and when the amplitude of the electric field standing wave is sparse, the amplitude of the magnetic field standing wave is dense. Therefore, the power receiver 3 can receive power from the electric field in a place where the amplitude of the electric field standing wave is dense, and from the magnetic field in a place where the amplitude of the magnetic field standing wave is dense. Further, in a place where both an electric field standing wave and a magnetic field standing wave exist, power can be received from both fields.

At this time, as shown in FIG. 2, the wireless power transmission system 1 is represented by a longitudinal connection of the transmitter 2, the structure 5, and the power receiver 3. When the scattering matrix of the structure 5 is S11, S12, S21, S22, the reflectance coefficient S11'viewing the receiver side from 1-1'shown in FIG. 2 and the reflectance coefficient Γ1 of the transmitter are shown in FIG. The reflection coefficient S22'when the transmission side is seen from 2-2'shown in 1 and the reflection coefficient Γ2 on the power receiving side are conjugate matching conditions, that is,
Complex conjugate Γ1 with reflectance coefficient Γ1 on the transmitter side ^*

受電器側の反射係数Γ２の複素共役Γ２^＊

Complex conjugate Γ2 with reflection coefficient Γ2 on the receiver side ^*

を満たすとき、インピーダンスの整合を確保できる。つまり、前記構造体５の散乱行列を変えることで送受電間の共役整合、すなわち、インピーダンス整合を確保できる。

When the condition is satisfied, impedance matching can be ensured. That is, by changing the scattering matrix of the structure 5, conjugate matching between power transmission and reception, that is, impedance matching can be ensured.

と求めることができる。 As for the scattering matrix of the structure 5, assuming that the reference impedance is Z0, for example, the impedance on the power transmission side is Z0, the impedance matrix of the structure 5 (Z11, Z12, Z21, Z22) is used.

Can be asked.

The impedance matrix of the structure 5 is obtained by the electromagnetic field standing wave generated inside the structure 5. Therefore, the scattering matrix of the structure 5 can be changed by changing the distribution of the electromagnetic field standing wave generated inside the structure 5 by the reactance element 6 and the impedance variable probe 7 provided in the structure 5.

That is, the electric field standing wave generated inside the structure 5 by reflecting the electric field in the place where the amplitude of the electric field standing wave is dense and reflecting the magnetic field in the place where the amplitude of the magnetic field standing wave is dense. The distribution can be changed.

For example, when the impedance variable probe 7 is a monopole-shaped reflective material made of a metal rod and is shorter than 1/4 wavelength of the transmission frequency, when the reactance element 6 is configured with a variable inductor, the value of the variable inductor increases as the value of the variable inductor increases. The electrical length of the variable impedance probe 7 can be increased. When the impedance variable probe 7 whose length is electrically extended reaches the region where the amplitude of the electric field standing wave generated inside the structure 5 is maximum, the electric field standing wave is reflected by the impedance variable probe 7. Therefore, the distribution of the electromagnetic field standing wave changes. As a result, the scattering matrix of the structure 5 changes.

For example, when the impedance variable probe 7 is a monopole-shaped reflective material made of a metal rod and is longer than 1/4 wavelength of the transmission frequency, when the reactance element 6 is composed of a variable capacitor, the value of the variable capacitor is increased. The electrical length of the variable impedance probe 7 can be shortened. When the impedance variable probe 7 whose length is electrically shortened reaches the region where the amplitude of the electric field standing wave generated inside the structure 5 is maximum to the region where the amplitude is minimum, the impedance variable probe 7 causes the impedance variable probe 7. Since the reflected electric field standing wave is not affected by the impedance variable probe 7, the distribution of the electromagnetic field standing wave changes. As a result, the scattering matrix of the structure 5 changes. As a result, impedance matching between power transmission and reception can be ensured without connecting a matching circuit to the power receiving device 3.

Consider a wireless power transmission system 9 in which at least one metal body 8 having at least one surface connected to the electromagnetic wave reflecting plate 4 is present inside the wireless power transmission system 1. For example, as shown in FIG. 3, when the transmitter 1 arranged inside the wireless power transmission system 9 is arranged in the z-axis direction from the center of the xy plane of the structure 5, the metal body 8 has an electric field standing. If it is placed at a position where waves are concentrated, electric field energy is stored, so it is capacitive. If the metal body 8 is placed at a position where magnetic field standing waves are concentrated, magnetic energy is stored, so it is inductive. show. That is, the metal body 8 operates as a reactance element. As a result, the resonance frequency _{fr2 m, n, p} of the wireless power transmission system 9, the wireless power transmission system 1 of the resonance frequency _{fr1 m, n,} than _p a low frequency. Therefore, in the wireless power transmission system 9, the electromagnetic field can be distributed throughout the wireless power transmission system 9 by setting the _{resonance frequencies fr2 m, n, and p to the transmission frequency.}

Wherein the wireless power transmission system 9, the transmission frequency resonance frequency fr2 m, _n, when set to _p, as in the case of the setting the transmission frequency in a wireless power transmission system 1 resonance frequency fr1 m, _n, to _p, As for the standing wave generated in the wireless power transmission system 9, the magnetic field standing wave becomes sparse in the place where the electric field standing wave is dense, and the magnetic field standing wave becomes dense in the place where the electric field standing wave is sparse. Therefore, it is possible to extract power from the electric field in the place where the amplitude of the electric field standing wave is dense, and from the magnetic field in the place where the amplitude of the magnetic field standing wave is dense. Further, in a place where both an electric field standing wave and a magnetic field standing wave exist, electric power can be extracted from both fields.

At this time, the wireless power transmission system 9 is represented by a longitudinal connection of the transmitter 2, the structure 5, and the power receiver 3 as shown in FIG. 2, similarly to the wireless power transmission system 1. When the scattering matrix of the structure 5 is S11, S12, S21, S22, the reflectance coefficient S11'looking at the receiver side from 1-1'and the reflectance coefficient Γ1 of the transmitter transmit from 2-2'. The reflection coefficient S22'looking from the side and the reflection coefficient Γ2 on the power receiving side are conjugate matching conditions, that is, the complex conjugate Γ1 ^* of the reflection coefficient Γ1 on the transmitter side obtained by [Equation 2] and [Equation 3], respectively, and the receiver. ^{When the complex conjugate Γ2 *} of the reflectance coefficient Γ2 on the electric appliance side is satisfied, the matching of the impedance can be ensured. That is, by changing the scattering matrix of the structure 5, conjugate matching between power transmission and reception, that is, impedance matching can be ensured.

The scattering matrix of the structure 5 can be obtained from the impedance matrix of the structure 5. The impedance matrix of the structure 5 is obtained by the electromagnetic field standing wave generated inside the structure 5. Therefore, the scattering matrix of the structure 5 can be changed by changing the distribution of the electromagnetic field standing wave generated inside the structure 5 by the reactance element 6 and the impedance variable probe 7 provided in the structure 5. As a result, even in the wireless power transmission system 9, impedance matching between power transmission and reception can be ensured without connecting a matching circuit to the power receiving device 3.

With such a configuration, the impedance of the wireless power transmission system can be changed, so that the received power can be efficiently extracted without connecting a matching circuit designed according to the power receiving location, and as a result, the wireless power can be extracted wirelessly. High efficiency of power transmission efficiency can be realized. This makes it possible to drive an electronic device connected to the power receiving device 3, for example, a sensor module having a temperature sensor, an illuminance sensor, a humidity sensor, and the like.

Further, consider a wireless power transmission system in which at least one insulator is present inside the wireless power transmission system 1. That is, it is a case where the metal body 8 of the wireless power transmission system 9 is replaced with the insulator. For example, when the transmitter 2 arranged inside the wireless power transmission system as in the wireless power transmission system 9 is arranged in the z-axis direction from the center of the xy plane of the structure 5, the insulator is electrified. If it is arranged at a position where the field standing wave is concentrated, it can be regarded as a capacitor because of the dielectric property of the insulator. On the other hand, if the insulator is arranged at a position where the magnetic field standing wave is concentrated, it can be regarded as an inductor from the magnetism of the insulator. That is, the insulator operates as a reactance element. As a result, the resonant frequency _{fr3 m, n, p} of the wireless power transmission system, the wireless power transmission system 1 of the resonance frequency _{fr1 m, n,} than _p a low frequency. Therefore, in the wireless power transmission system, the same effect as that of the wireless power transmission system 1 can be obtained by setting the _{resonance frequencies fr3 m, n, p to the transmission frequency.}

Further, consider the case where a plurality of the power receiving devices 3 are arranged. Even in such a case, from the electric field in the place where the amplitude of the electric field standing wave is dense, from the magnetic field in the place where the amplitude of the magnetic field standing wave is dense, both in the place where both the electric field standing wave and the magnetic field standing wave exist. Power can be extracted from the field at the same time.

When the electric power is extracted from the plurality of electric power receivers 3 arranged at the same time, the electric power received per one of the electric power receivers 3 is reduced because the electric power is distributed, but the value of the reactance element 6 and / or By varying the electrical length of the impedance variable probe 7 with time, impedance matching between the receiver and the transmitter 2 is ensured at a certain time, and impedance matching between another receiver and the transmitter 2 at a certain time. Is secured. That is, it is possible to create a situation in which the transmitter 2 and the receiver 3 are one-to-one by receiving power in a time-division manner by each receiver 3. As a result, the received power per power receiver can be improved.

By setting the transmission frequency to the ground resonance frequency, electric power can be transmitted at the lowest frequency, so that the efficiency of the rectifier circuit can be improved. As a result, the wireless power transmission efficiency can be improved.

By setting the transmission frequency to the higher-order mode resonance frequency, the sparse and dense region of the electromagnetic field standing wave increases, so that the reactance element 6 and / or the impedance variable probe 7 can be placed in more places, so that impedance matching can be achieved. It becomes easy, and high efficiency of power receiving efficiency can be realized. As a result, the wireless power transmission efficiency can be improved.

When the electromagnetic wave reflecting plate 4 is replaced with, for example, a metal such as copper or iron, a conductive material having a high relative magnetic permeability, or a mesh or a net made of them, the electromagnetic wave reflecting plate 4 is operated as an electromagnetic wave reflecting plate only at a frequency to which power is supplied. be able to. Therefore, a frequency different from the frequency for transmitting power, for example, a frequency for performing information communication passes through a mesh or a network, so that information communication should be controlled from outside the wireless power transmission system 1 or from outside the wireless power transmission system 9. Can be done. For example, sensing instructions and sensing data can be transmitted and received inside the wireless power transmission system 1 or inside the wireless power transmission system 9 outside the wireless power transmission system 1 or outside the wireless power transmission system 6.

When the electromagnetic wave reflecting plate 4 is replaced with, for example, a conductive material having a high specific magnetic permeability, or a mesh or net made of copper, iron, or the like, the electromagnetic wave reflecting plate 4 is completely shielded with metal at the transmission frequency as compared with the case where the electromagnetic wave reflecting plate 4 is completely shielded with metal. Operates as a high impedance surface. Therefore, since the impedance range of the structure 5 that can be changed by the reactance element 6 and / or the impedance variable probe 7 can be widened, impedance matching can be facilitated and high efficiency of power receiving efficiency can be realized. As a result, the wireless power transmission efficiency can be improved.

When the power receiver 3 is replaced with a shape such as a dipole shape or a loop shape that takes out electric power by a potential difference due to a differential, the reference potential can be secured by the power receiver 3 itself, so that the power receiver 3 is connected to the structure 5. Power can be taken out without any need. As a result, the receiver can be placed at any location.

The electromagnetic wave reflecting plate 4 shown in FIG. 4 is made of aluminum, the transmitter 2 and the power receiver 3 are copper monopole probes, the reactance circuit in which the reactance element 6 is provided on a dielectric substrate, and the impedance variable probe 7. Consider the radio power transmission system 9 made of a copper monopole probe, the metal body 8 and obstacles 10, 11, 12, and 13 made of aluminum.

For example, the internal dimensions of the wireless power transmission system 9 are 470 mm in the x-axis direction, 473 mm in the y-axis direction, and 800 mm in the z-axis direction. Each surface of the wireless power transmission system 9 is electrically connected. Of the wireless power transmission system 9, the transmitter 2 is arranged on the surface 15 facing the surface 14 on which the obstacle 13 is arranged. The surface of the obstacle 10 in which the power receiver 3 is arranged is referred to as a surface 16.

In the power transmitters and receivers 2 and 3, for example, as shown in FIG. 5, a copper wire 19 is soldered to the central conductor 18 of the panel mount type SMA connector 17, and the surfaces 14 and 15 are, for example, by screws and nuts. Can be fixed to. Similarly, as shown in FIG. 5, the impedance variable probe 7 can also be composed of the SMA connector 17 and the copper wire 19, and can be fixed to the structure 5 with screws and nuts.

The reactance element 6 can be realized by, for example, a circuit in which a chip inductor and / or a chip capacitor is mounted on a microstrip line provided on a dielectric substrate having a relative permittivity of 3.4 and grounded to GND by a through hole. The impedance variable probe 7 is connected to the impedance variable probe 7 via an SMA connector or the like, and the GND on the circuit can be connected to the structure 5 via the GND of the SMA connector.

For example, the transmitter 2 is attached at a position where the center thereof and the center of the surface 15 coincide with each other, and the power receiver 3 is attached at a position where the center thereof coincides with the center of the surface 16. That is, the obstacles 10 and 12 have a size of 300 mm in x-coordinate and 400 mm in y-coordinate, and a thickness of 2 mm. The obstacles 11 and 13 arranged at the four corners of the scatterers 10 and 12 have heights of 300 mm and 100 mm, respectively, and have an L-shape having a length of 25 mm and a width of 2 mm in the x-axis direction and the y-axis direction, respectively. Let it be an angle. The obstacles 10, 11, 12, and 13 are fixed with, for example, steel screws in order to conduct electricity with the surface 14.

The basal resonance frequency of the wireless power transmission system 1 excluding the obstacles 10, 11, 12, and 13 is calculated from the internal dimensions thereof.

と求められる。

Is required.

On the other hand, the wireless power transmission system 9 including the obstacles 10, 11, 12, and 13 may have a lower resonance frequency due to the ridge effect than the wireless power transmission system 1. This resonance frequency can be easily calculated from the structure by using an electromagnetic field simulation or the like. For example, the ground resonance frequency of the structure shown in FIG. 4 is 450.3 MHz. Therefore, the frequency used for power transmission is set to 450.3 MHz.

It should be noted that high-order mode resonance, in which the number of sparse and dense electromagnetic field standing waves is large, may be set as the frequency used for power transmission because of the variability of impedance.
In such a configuration, for example, when the frequency used for power transmission is set to the TE112 mode, which is the higher-order mode of FIG. 4, the frequency becomes 587.7 MHz. At this time, by setting the lengths of the copper wires 18 constituting the power transmission / reception devices 2 and 3 to 83 mm, the power transmission efficiency becomes 87.0%.

Here, for example, the impedance variable probe 7 having a monopole shape with a copper wire 18 having a length of 83 mm is surfaced from the centers of two sides parallel to the x-axis and two sides parallel to the y-axis of the surface 15. When a total of four reactance elements are fixed at a length of 195 mm in the z-axis direction toward the 14 side, the reactance value of the reactance element 6 is connected to the impedance variable probe 7 provided with two sides parallel to the x-axis. The reactance element 6 is provided on the surface 16 so that the reactance element 6 is 139.7 Ω, and the reactance element 6 connected to the impedance variable probe 7 provided on two sides parallel to the y-axis is designed to be 435.8 Ω. The power transmission efficiency to the power receiver 3 is improved to 87.6%. A reactance value showing a positive value can be realized by using an inductor, and a reactance value showing a negative value can be realized by using a capacitor.

On the other hand, for example, as shown in FIG. 6, the power receiver 3 is arranged on the surface 20 of the scatterer 12 in which the scatterer 11 is arranged so as to be out of the line of sight of the transmitter 2, and the transmitter 2 is arranged. And the length of the copper wire 19 constituting the power receiving device 3 is set to 83 mm, respectively. At this time, the frequency used for power transmission is the TE112 mode, which is the higher-order mode of FIG. 4, that is, 587.7 MHz. The power transmission efficiency is 83.4%.

Here, for example, the impedance variable probe 7 having a monopole shape with a length of 83 mm of the copper wire 18 is surfaced from the centers of two sides parallel to the x-axis and two sides parallel to the y-axis of the surface 15. When a total of four reactance elements are fixed at a length of 200 mm in the z-axis direction toward the 14 side, the reactance value of the reactance element 6 is connected to the impedance variable probe 7 provided with two sides parallel to the x-axis. The reactance element 6 is designed to be 109.0 Ω, and the reactance element 6 connected to the impedance variable probe 7 provided on two sides parallel to the y-axis is designed to be 493.3 Ω on the surface 20. The power transmission efficiency to the provided receiver 3 is improved to 88.4%. A reactance value showing a positive value can be realized by using an inductor, and a reactance value showing a negative value can be realized by using a capacitor.

This makes it possible to drive an electronic device connected to the power receiving device 3, for example, a sensor module having a temperature sensor, an illuminance sensor, a humidity sensor, and the like.

The electromagnetic wave reflecting plate 4 is not limited to a metal plate, and is a material that reflects electromagnetic waves, such as a metal such as copper or iron whose mesh is sufficiently shorter than the wavelength of the frequency used for power transmission, or a conductive material having a high relative permeability. But it can be substituted. This makes it possible to reduce the weight and ensure breathability, and it can be applied to a wider range of applications.

1, 9 Wireless power transmission system 2 Transmitter 3 Power receiver 4 Electromagnetic wave reflector 5 Structure 6 Reactance element 7 Impedance variable probe 8, 10, 11, 12, 13 Obstacle 14 Obstacle 13 surface 15 surface Surface that opposes 14 16 Surface of obstacle 10 17 SMA connector 18 Center conductor 19 Copper wire 20 Surface on which obstacle 11 is placed

Claims (6)

Includes whole and is surrounded structure, and at least one power transmission unit and at least one power receiving unit installed in the interior of the structural member by an electromagnetic wave reflecting member formed of a material having a specific magnetic permeability,
The power transmission unit transmits an electromagnetic wave having a resonance frequency when the structure is assumed to be a waveguide resonator.
Radio power characterized by impedance matching between transmission lines between the power transmission unit and the power reception unit by an impedance variable probe that can be regarded as at least one reactance element installed inside the structure. Transmission system. The wireless power transmission system according to claim 1, wherein the variable impedance probe that can be regarded as the reactance element can change the reactance value. The wireless power transmission system according to claim 1 or 2, wherein the structure uses an electromagnetic wave reflecting member of a type partially different from the others. The wireless power transmission system according to any one of claims 1 to 3, wherein the electromagnetic wave reflecting member surrounding the structure has a through hole in a part or the whole. The through hole, the wireless power transmission system according to claim 4, wherein some or all of the electromagnetic wave reflecting member, and wherein the a material having a specific magnetic permeability are those provided by forming a mesh-like .. When an obstacle made of a metal body and / or an insulator is installed inside the structure, the resonance frequency is set to a resonance frequency calculated by regarding the obstacle as a reactance element. The wireless power transmission system according to any one of claims 1 to 5.

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