JP2020089209A - Power transmitter and receiver, and wireless power transmission system using the same - Google Patents

Abstract

To provide a power transmitter, a power receiver and a wireless power transmission system, enabling easy impedance matching with the suppression of the deterioration of power transmission efficiency inside a structure which reflects an electromagnetic wave therein.SOLUTION: A power transmitter 5 of the wireless power transmission system has an electric connection among a linear metal wire 8 of which one end is an open end, a dielectric substrate 9 and at least one or more conductor posts 10, and further, an electric connection to a matching circuit, so as to transmit power. A power receiver has first and second power receivers arranged in parallel to face each other. The first power receiver electrically connects a first linear conductor line of which one end is an open end to at least one or more first conductor posts at the other end that is not the open end. The second power receiver electrically connects a second conductor line arranged to face the first conductor line to at least one or more second conductor posts at the other end of the second conductor line that is not the open end.SELECTED DRAWING: Figure 3

Description

The present invention relates to a power transmitter that transmits high frequencies and a wireless power transmission system that uses the power transmitter. In particular, the present invention relates to a structure and an electronic device for wirelessly supplying electric power to and transmitting and receiving information to a sensor or the like installed in a pipe or an engine room surrounded by a metal having an obstacle such as a metal body or an insulator or in a factory. ..

A wireless power transmission system to a place surrounded by a metal having an obstacle such as a metal body or an insulator transmits and receives power by utilizing a resonance phenomenon in which an electromagnetic field is confined in the shield structure by utilizing a metal shielding effect. ..

For example, in Non-Patent Document 1, a structure entirely surrounded by a metal wall and shielded from electromagnetic waves, a power transmitter including a gold rod installed inside the structure, and a plurality of metal rods in a circular shape. One power receiver that is wound, and the power transmission unit transmits an electromagnetic wave at a resonance frequency when the structure itself is assumed to be a waveguide resonator, and a power receiver designed to resonate at the resonance frequency. A wireless power transfer system having is disclosed.

In such a conventional wireless power transmission system, in order to achieve high power transmission efficiency, the structure of the power transmitter is a monopole type structure in which metal rods are vertically arranged. There are restrictions on the placement of. The power receiver uses a coil-type small resonator wound in a plurality of circles, but the power transmission efficiency is less than 10% due to miniaturization.

H. Mei, KA Thanckston, RA Bercich, JGR Jefferys, and PP Irazoqui, “Cavity Resonator wireless power transfer system for freely moving animal experiments,” IEEE Biomed. Eng., vol. PP, no. 99, pp. 1-1 June 2016.

In a conventional wireless power transmission system, a capacitive coupling element has been realized by using a monopole type power transmitter in order to efficiently excite a standing wave of an electromagnetic wave in a shielding structure likened to a resonator. Since the value of the capacitive coupling element can be adjusted by adjusting the length of the monopole type power transmitter, it is easy to match the impedance of the shielding structure like the power transmitter and the resonator, but the length of the power transmitter is The length is about ⅛ of the above, and there is a restriction on the arrangement of the device and the like in the pipe surrounded by the metal having the metal body or the insulator, the engine room, the inside of the factory and the like. Further, if the size of the device or equipment in the shield structure is reduced to reduce restrictions, impedance matching between the resonator and the shield structure becomes difficult, and the power transmission efficiency deteriorates significantly.

The present invention has been made to solve the above problems, and realizes a miniaturized power transmitter/receiver with easy impedance matching and a wireless power transmission system using the same.

A wireless power transmission system according to the present invention includes a structure entirely surrounded by an electromagnetic wave reflection member formed of a material having an appropriate relative magnetic permeability, and at least one power transmission section installed inside the structure. At least one power receiving unit,
The power transmission unit transmits/receives an electromagnetic wave having a resonance frequency when the structure body is assumed to be a waveguide resonator, and the power reception unit includes a first power receiver and a second power receiver. And
The power transmission unit electrically includes a conductor wire made of a linear metal, one of which is an open end, a dielectric substrate that holds the conductor wire, at least one or more conductor posts, and a matching circuit. It is made by connecting,
The first power receiver electrically connects a linear first conductor wire, one of which is an open end, and at least one or more first conductor pillars at the other end which is not the open end of the first conductor wire. Are connected together,
The second power receiver includes a second conductor wire arranged to face the first conductor wire and at least one second conductor pillar at the other end which is not an open end of the second conductor wire. When electrically connected, the axis of the first conductor column and the axis of the second conductor column are arranged to face each other on the same straight line, and a virtual plane orthogonal to the straight line is used as a plane of symmetry. The second conductor wire is symmetrical to the first conductor wire,
Impedance matching is performed between transmission lines between the power transmission unit and the power reception unit.

With the above configuration and structure, the reflected power generated at the connection between the power transmitter and the wireless power transmission system can be reduced most, and the power can be efficiently generated without using the power transmitter in which the metal rod is vertically arranged like the monopole type. It can be powered wirelessly.

Further, in the power transmission section of the wireless power transmission system according to the present invention, the total length of the conductor wire and the conductor column of the power transmitter is shorter than 1/4 of the wavelength of the resonance frequency peculiar to the structure. In addition, it operates as a capacitive element.

Furthermore, in the power receiving unit of the wireless power transmission system according to the present invention, the combined length of the conductor wire of each of the first power receiver and the second power receiver and the length of the conductor pillar are both the structure. It is characterized in that it is shorter than 1/4 of the wavelength of the natural resonance frequency and operates as a capacitive element.

In the power receiving unit, it is not necessary to configure the power receiver with a resonator, and the matching between the power receiver and the electromagnetic wave shielding structure becomes easy.

ADVANTAGE OF THE INVENTION According to this invention, even if the visibility of the power transmission part and the power reception part of a wireless power transmission system is bad, the power required for the power reception part is supplied highly efficiently, without restricting the arrangement of devices and equipment in the electromagnetic wave shielding structure. become able to.

It is a block diagram of the wireless power transmission system 1 which concerns on this invention. It is a block diagram of the power transmission part 2 which concerns on this invention. It is a schematic diagram of the power transmitter 5 in the power transmission part 2 which concerns on this invention. It is a schematic diagram of the power receiver 11 in the power receiving unit 3 according to the present invention. It is a conceptual diagram in case the obstacle 18 is provided inside a resonator structure in a wireless power transmission system. It is a schematic diagram showing an example of the electromagnetic wave reflection plate which comprises a resonator structure in a wireless power transmission system. It is a schematic diagram showing an example of the obstacle 18 which concerns on Example 1 of this invention. It is a schematic diagram of the SMA connector which connects the variable matching circuit 6 and the power transmitter 5 which concern on Example 1 of this invention. It is a schematic diagram showing an example which has arrange|positioned the power receiver 11 in the power receiving part 3 which concerns on Example 1 of this invention. It is a schematic diagram of the wireless sensor module 33 according to the first embodiment of the present invention. The wireless sensor module 33 is configured by electrically connecting the rectifier circuit 31 and the sensor module 32 having a wireless communication function.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. A 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 feeding system according to the present invention. In FIG. 1, a wireless power transmission system 1 includes at least one power transmission unit 2 and at least one power reception device 3 inside, and the wireless power transmission system 1 includes an electromagnetic wave reflection plate 4 that is a material that reflects electromagnetic waves. The whole area is surrounded by. That is, the wireless power transmission system 1 refers to the entire structure that realizes wireless power feeding.

The configuration of the power transmission unit 2 will be described with reference to FIG. The power transmission unit 2 includes a power transmitter 5 for transmitting high frequency power and a variable matching circuit 6, and the variable matching circuit is connected to, for example, a high frequency power supply 7. The variable matching circuit 6 is connected between the power transmitter 5 and the high frequency power supply 7, and is connected for the purpose of preventing the high frequency power output from the high frequency power supply 7 from being reflected by the power transmitter 5 and flowing back to the high frequency power supply 7. ..

As shown in FIG. 3, the power transmitter 5 includes a conductor wire 8 made of a linear metal, one of which is an open end, a dielectric substrate 9 holding the conductor wire 8, a conductor wire 8 and the variable matching. It comprises at least one or more conductor posts 10 connecting the circuits 6.

Since the wireless power transmission system 1 has a space shielded by the electromagnetic wave reflection plate 4, it can be considered as a waveguide resonator. Therefore, in the wireless power transmission system 1, the resonance frequency fr _m,n,p (Equation 1) obtained from the side length a in the x-axis direction, the side length b in the y-axis direction, and the side length c in the z-axis direction. ) Is set to the power transmission frequency, the electromagnetic field can be distributed throughout the wireless power transmission system 1.

ここで、ｖは光速、μ_ｒは比透磁率、ε_ｒは比誘電率、ｍ、ｎ、ｐはそれぞれ整数を示している。

Here, v is the speed of light, μ _r is the relative permeability, ε _r is the relative permittivity, and m, n, and p are integers.

In order to feed the high frequency power having the resonance frequency fr _m,n,p into the wireless power transmission system 1, the total length of the metal wire 8 and the conductor column 10 of the power transmitter 5 is equal to the resonance frequency fr _{m, By} setting the wavelength shorter than 1/4 wavelength of _{n and p} , it can be operated as a capacitive element. Since the wireless power transmission system 1 operates as a waveguide resonator and the power transmitter 5 operates as a capacitive element, the wireless power transmission system 1 is a resonance circuit of a high frequency filter, and the power transmitter 5 is an immittance swiver composed of an electric field coupling element. Has the same role as. That is, at the resonance frequency fr _m,n,p , matching between the power transmitter 5 and the wireless power transmission system 1 becomes easy, so that power can be efficiently fed without using a rod-shaped power transmitter such as a monopole type. Can be powered wirelessly.

The power transmitted from the power transmitter 5 is received by the power receiver 11 shown in FIG. The power receiver 11 includes a conductor wire 12 on a wire of which one end is an open end, a power receiver component 14 including at least one or more conductor pillars 13 connected to the other end of the conductor wire 12, and a conductor wire 12 facing each other. The power receiving part 17 includes a conductor wire 15 and a conductor pillar 16 connected to the other end of the conductor wire 15. The power receiver 5 is arranged on the same straight line connecting the axis of the conductor column 13 and the axis of the conductor column 16 so as to face each other, and the conductor line 12 and the conductor line 15 have a symmetrical structure.

In the power receiver 11, the total length of the conductor wire 12 and the conductor pillar 13, that is, the length of the power receiver component 14, the total length of the conductor wire 15 and the conductor pillar 16, that is, the power receiver component 17 Can be operated as a capacitive element by setting the lengths of the wavelengths shorter than the quarter wavelengths of the resonance frequencies fr _m,n,p . Since the wireless power transfer system 1 operates as a waveguide resonator and the power receiver 11 operates as a capacitive element, the wireless power transfer system 1 is a resonance circuit of a high frequency filter, and the power receiver 11 is an immittance swiver composed of an electric field coupling element. Has the same role as. That is, at the resonance frequency fr _m,n,p , matching between the power transmitter 5 and the wireless power transmission system 1 becomes easy. Further, since the conductor wire 12 and the conductor wire 13 have a symmetrical structure, the symbols of the power receiver component 14 and the power receiver component 17 are paired capacitive elements having electric charges by the electric imaging method, and thus the power receiver 11 Can be operated as a differential type power receiver without operating as a 1/2 wavelength resonator having a resonance frequency fr _m,n,p . As a result, it is not necessary to configure the power receiver with a resonator, and the matching between the power receiver and the shield structure is easy, so that the power required for the power receiver can be supplied with high efficiency even if the visibility of the power receiver and the power receiver is poor. realizable.

When the electromagnetic wave reflection plate 4 is replaced with, for example, a metal such as copper or iron or a conductive material having a high relative magnetic permeability, or a mesh or net made of them, it operates as an electromagnetic wave reflection plate only at a frequency at which power is supplied. be able to. Therefore, since the frequency for performing information communication passes through the mesh or the network, the information communication can be controlled from outside the wireless power transmission system 1. For example, it is possible to send and receive sensing instructions and sensing data inside the wireless power transmission system 1 outside the wireless power transmission system 1.

For example, consider the wireless power transmission system 19 shown in FIG. 5 including the power transmitter 5 shown in FIG. 3, the power receiver 11 shown in FIG. 4, and an obstacle 18 made of aluminum. The electromagnetic wave reflectors 4 forming the wireless power transmission system 19 are all conductively connected. For example, as shown in FIG. 6, five surfaces of the electromagnetic wave reflection plate 4 are metal nets that are connected on a grid by using a plurality of chrome-plated steel wires 20. The size of the grid is 12 mm×12 mm, and the diameter of the steel wire is 1 mm. The remaining one surface is made of an aluminum plate. The lattice size is 1/16 or less of the wavelength of the base resonance frequency of the wireless power transmission system 19, and 1/8 or more of the wavelength of the information transmission frequency for transmitting/receiving the sensor information.

It should be noted that the electromagnetic wave reflection plate 4 can be realized with a high shielding property if it is made of a metal plate. Further, by expressing the electromagnetic wave reflection plate 4 entirely by a metal net, it is possible to reduce the weight and ensure the air permeability, and it is possible to apply to a wider range of applications. Alternatively, the electromagnetic wave reflection plate 4 has a metal net structure in which a transparent electrode is formed on a transparent thin film, so that further weight reduction and easy installation can be realized.

Furthermore, the six sides of the wireless power transmission system 19 can firmly maintain the shape of a rectangular parallelepiped by fixing each side with a frame made of aluminum, and realize high conductivity.

The internal dimensions of the wireless power transmission system 19 are 473 mm in the x-axis direction, 470 mm in the y-axis direction, and 800 mm in the z-axis direction. It is assumed that the surface of the wireless power transmission system 19 on which the power transmitter 5, the power receiver 11 and the obstacle 18 are arranged is a surface 21, and the surface 21 is made of an aluminum plate. For example, the obstacle 18 is composed of four metal columns 22, 23, 24, 25 and two metal plates 26, 27. The four metal columns 22, 23, 24, 25 are fixed so as to be electrically connected to the squares of the metal plates 26, 27, respectively. For example, each of the metal columns 22, 23, 24, and 25 is made of aluminum and has a size of 30 mm in the x-axis direction, 30 mm in the y-axis direction, and 400 mm in the z-axis direction. Each of the metal plates 26 and 27 is also made of aluminum and has a size of 400 mm in the x-axis direction, 300 mm in the y-axis direction, and a thickness of 2 mm. The ends of the metal columns 22, 23, 24, 25 that are not fixed to the metal plate 26 are fixed so as to be electrically connected to the surface 21. The metal shelves 27 are electrically connected to the ends of the metal columns 22, 23, 24, 25 at a position of 100 mm in the z-axis direction from the connection surface between the other ends of the metal columns 22, 23, 24, 25 and the surface 21. Fixed. The metal plates 26, 27 are arranged so that the midpoint of the metal plates 26, 27 coincides with the midpoint of the surface 21.

The dielectric substrate 9 of the power transmitter 5 shown in FIG. 3 is a dielectric substrate having a relative dielectric constant of 3.4, and the conductor lines 8 are expressed by microstrip lines made of copper thereon. For example, the size of the dielectric substrate 9 is 100 mm in the x-axis direction, 20 mm in the y-axis direction, the conductor line 8 has a width of 2 mm and a length of 80 mm, and the center of the short side of the dielectric substrate 9 and the center of the width of the conductor line are. Arranged to match. The conductor column 10 is made of copper. For example, a hole having a diameter of 1 mm is made at one end of the conductor wire 8, a conductor column 10 having the same diameter and a length of 20 mm is inserted, and fixed by soldering. For example, one end of the conductor post 10 of the power transmitter 5 is soldered to the center conductor 29 of the panel mount type SMA connector 28 as shown in FIG. 8, and the outer conductor 30 is screwed and nuted to the electromagnetic wave reflection plate 4 or the obstacle 18. Can be fixed to. In the power transmitter, the dielectric substrate 9 is a transparent thin film and the conductor wire 8 is a transparent electrode, so that the same performance can be maintained without blocking the view.

The conductor wires 12 and 15 of the power receiver 11 shown in FIG. 4 are represented by, for example, a microstrip line made of copper on a dielectric substrate having a relative dielectric constant of 3.4 for the purpose of maintaining the shape, and the conductor pillars 13 and Both 16 are realized by aluminum. The conductor wires 12 and 15 have the same length as 105 mm, are bent at a right angle of 40 mm from the open end to form a length of 25 mm, and are further bent at a right angle and have a length of 40 mm. A hole having a diameter of 1 mm is formed in the other ends of the conductor wires 12 and 15, and one ends of conductor columns 13 and 16 having the same diameter and a length of 10 mm are inserted and fixed by soldering. The other ends of the conductor columns 12 and 15 are fixed to a circuit board on which a power receiving circuit is formed, for example, by soldering to realize a power receiving unit. Although the conductor wire of the power receiver is U-shaped in FIG. 4, the shape of the conductor wire is not limited to this and may be symmetrically arranged.

For example, the power transmitter 5 is at a position where the x coordinate of the wireless power transmission system 19 is 198 mm, the coordinate is 235 mm, and the z coordinate is 800 mm, that is, on the electromagnetic wave reflection plate 4, and the power receiver 11 is the metal plate 26 of the obstacle 18, It is attached to the surface facing the power transmitter 5 at a position where the x coordinate is 218 mm and the y coordinate is 223.5 mm. Here, it is assumed that the coordinate positions of the power transmitter 5 and the power receiver 11 are determined on the basis of the center conductor 14 and the conductor columns 13 and 16. The power transmitter 5 and the power receiver 11 are positioned within the line of sight of each other.

The base resonance frequency of the wireless power transmission system 1 that does not include the obstacle 18 can be obtained from the internal dimensions by the calculation formula (Equation 2).

On the other hand, the resonance frequency of the wireless power transmission system 19 including the obstacle 18 changes from that of 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 structure shown in FIG. 3 is 453 MHz. Therefore, the frequency used for power transmission is 453 MHz.

In such a configuration, the power transmission efficiency is 97% when the power transmission/reception system including the power transmission device 5 and the power reception device 11 is impedance-matched.

On the other hand, the power receiver 11 is located outside the line-of-sight of the power transmitter 5, for example, the x-coordinate of 85 mm and the y-coordinate of 135 mm on the surface of the metal shelf 27 of the shield 11 facing the metal shelf 26 as shown in FIG. The power transmission efficiency after impedance matching when moved to a position outside the line of sight is 90%.

As a result, it is possible to drive an electronic device such as a sensor module such as a temperature sensor, an illuminance sensor, or a humidity sensor, which is connected to the power receiver 11.

Since a virtual ground plane is provided between the dielectric substrates 9 holding the two metal wires 12 and 15 of the power receiver 11, it is possible to insert a circuit between the dielectric substrates 9. For example, as shown in FIG. 10, a wireless sensor module 33 including a rectifier circuit 31 and a sensor module 32 having a wireless communication function is arranged.

In such a configuration, the wireless sensor module 33 can obtain DC power by connecting the rectifier circuit 31 to the conductor columns 13 and 16 that serve as the output section of the power receiver 11. For example, when a load resistance of 10 kΩ is connected to the rectifier circuit 31, the DC output power can be measured from the voltage applied to the load resistance. The power transmission efficiency can be calculated from the ratio of the DC output power and the power input to the power transmitter 5.

Further, for example, the power receiver 11 is disposed on the metal plate 26 of the obstacle 18 on the surface facing the power transmitter 5 at a position where the x coordinate is 198 mm and the coordinate is 235 mm, and the rectifying current circuit 31 is the double voltage rectifying circuit. In the case of the above configuration, if 15.9 dBm is input to the power transmitter 5, the power transmission efficiency will be 49.0%. The power transmission efficiency at the same position on the metal plate 27 outside the line of sight is 36.9%. When the x coordinate of the metal plate 26 is 85 mm and the y coordinate is 135 mm, the percentage is 20.3%, and the same position of the metal plate 27 is 10.9%.

Further, for example, when the sensor module 32 is an illuminance sensor and the wireless communication function is Zigbee, when the x-coordinate is 198 mm and the coordinate is 235 mm at a position facing the power transmitter 5, the metal is out of sight. The wireless sensor module 33 can be driven even when arranged at the same position on the plate 27, arranged at the x coordinate of 85 mm and the y coordinate of 135 mm of the metal plate 26, and arranged at the same position of the metal plate 27. Furthermore, by expressing the electromagnetic wave reflection plate 4 entirely by a metal net, the information from the wireless sensor module 33 can be received outside the wireless power transmission system 1.

1, 19 Wireless Power Transmission System 2 Power Transmitter 3 Power Receiver 4 Electromagnetic Wave Reflector 5, Power Transmitter 6, Variable Matching Circuit 7, High Frequency Power Supplies 8, 12, 15 Metal Wire 9, Dielectric Substrate 10, 13, 16 Conductor Column 11 , Power receiver 14, 17 power receiver component 18, obstacle 20, steel wire 21, surface 22, 23, 24, 25 metal column 26, 27 metal plate 28, SMA connector 29, center conductor 30, outer conductor 31, rectifier circuit 32, sensor module 33, wireless sensor module

Claims (3)

A structure body entirely surrounded by an electromagnetic wave reflection member formed of a material having an appropriate relative magnetic permeability, and at least one power transmission unit and at least one power reception unit installed inside the structure body,
The power transmission unit transmits/receives an electromagnetic wave having a resonance frequency when the structure body is assumed to be a waveguide resonator, and the power reception unit includes a first power receiver and a second power receiver. And
The power transmission unit electrically includes a conductor wire made of a linear metal, one of which is an open end, a dielectric substrate that holds the conductor wire, at least one or more conductor posts, and a matching circuit. It is made by connecting,
The first power receiver electrically connects a linear first conductor wire, one of which is an open end, and at least one or more first conductor pillars at the other end which is not the open end of the first conductor wire. Are connected together,
The second power receiver includes a second conductor wire arranged to face the first conductor wire and at least one second conductor pillar at the other end which is not an open end of the second conductor wire. When electrically connected, the axis of the first conductor column and the axis of the second conductor column are arranged to face each other on the same straight line, and a virtual plane orthogonal to the straight line is used as a plane of symmetry. The second conductor wire is symmetrical to the first conductor wire,
A wireless power transmission system, wherein impedance matching is performed between transmission lines between the power transmission unit and the power reception unit. The power transmission unit is such that the combined length of the conductor wire and the conductor column of the power transmitter is shorter than 1/4 of the wavelength of the resonance frequency peculiar to the structure, and operates as a capacitive element. The wireless power transmission system according to claim 1, wherein: In the power receiving unit, the total length of the conductor wires of the first power receiver and the second power receiver and the length of the conductor column are both ¼ of the wavelength of the resonance frequency peculiar to the structure. The wireless power transmission system according to claim 1, wherein the wireless power transmission system is shorter and operates as a capacitive element.

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