JP6827354B2 - Wireless power supply - Google Patents

Description

The present invention relates to a wireless power feeding device that performs non-contact (wireless) power transmission between a power transmitting device and a power receiving device, and relates to a wireless power feeding device in which the power receiving device can be moved.

As a method of transmitting electric power in a non-contact manner (hereinafter referred to as wireless power feeding), an electromagnetic induction method using electromagnetic induction, a resonance power feeding method via electric field or magnetic field resonance, a microwave power transmission method using radio waves, and the like are known. Of these, the electromagnetic induction method has already been commercialized and is commonly seen. Although this method has a simple design and enables highly efficient wireless power supply, it also has a problem that the transmission distance is short. Therefore, a resonance feeding method has been proposed in which electric power is transmitted up to several meters by using resonance, and product development using this technology is being promoted mainly by electric appliance makers and automobile makers.

In the resonance power feeding method, power transmission is performed by electromagnetically coupling the power transmission coil in the power transmission device and the power reception coil of the power reception device. While the coupling coefficient k value between the two coils is small, wireless power supply is performed by increasing the Q value, but the transmission distance can be lengthened as compared with the electromagnetic induction method, but the power transmission efficiency is low.

It must be an advantage to be able to increase the transmission distance, but it also poses a risk. For example, there is an increasing concern about safety, such as people / things (things different from the original power receiving target) approaching or even entering between the power transmission device and the power receiving device. That is, in practical operation, it becomes necessary to pay attention to electromagnetic exposure to the human body and precision electronic devices, and further, it is important to take measures when a metallic foreign substance is sandwiched between them.

For example, in the wireless power supply device disclosed in Patent Document 1, the positions of the user and the power supply device are detected and notified, and the operating state of the power supply device is controlled. According to this method, when a user (person) exists, the amount of electromagnetic exposure received by the user is reduced by reducing the power supply power.

Japanese Unexamined Patent Publication No. 2014-60822

In Patent Document 1, the amount of power supplied is controlled by the positional relationship between the user and the power supply device. However, the scale of the device becomes large, such as the need for a separate device that detects and notifies the positional relationship between the user and the power feeding device, and as a result, the cost also increases.

In addition, when applying wireless power supply to a form that is essentially intended to be shown to people, such as exhibits and show windows, and to attract people, the amount of power supply is suppressed when a person approaches in the first place. You can't do that.

In order to solve the above problems, the wireless power feeding device of the present invention includes a power transmission device having a power transmission resonator composed of a power transmission coil and a resonance capacitance, and a power reception device having a power reception resonator composed of a power reception coil and a resonance capacitance. And, the power is transmitted from the power transmitting device to the power receiving device in a non-contact manner through the action between the power transmitting coil and the power receiving coil, and the power receiving device is transmitted from the outside through a transparent or translucent partition. Although it is visible, keep people and objects other than the power receiving object away from the power transmission device and the vicinity of the power receiving device. The power transmission coil and the power reception coil are arranged so that wireless power transmission can be performed more efficiently, and the positional relationship of the partitions is properly adjusted so that the power reception device operates within a certain range of the power transmission device.

Here, especially when considering exhibits and show windows, visibility from the outside to the inside is the most important issue. For this reason, the above partitions should be made of glass or plastic with as high transparency as possible, and the exhibition space and show window where the exhibits will be placed should be as large as possible. However, as a result of the verification by the inventors, in the above-mentioned glass and plastic which are dielectrics, an unnecessary leaking magnetic field generated by wireless power supply (that is, it leaks to the outside of the exhibit or the show window and affects other people and things. It was found that the magnetic field that exerts a force) can hardly be prevented and is reduced when a metal thin film having a relatively high conductivity is formed by sputtering or the like. However, if a metal film is formed and the thickness is increased until the unnecessary leakage magnetic field is reduced, the transparency, which is important for the visibility, is lowered, and the original purpose cannot be sufficiently achieved.

In addition, in order to increase the exhibition space and show window to provide a large space for power supply by wireless power supply, it is inevitably necessary to increase the wireless power supply input power. According to the verification by the inventors, if the wireless power supply is performed in a wide space as described above, the magnetic field leaking to the outside of the exhibition space or the show window will increase, and the wireless power supply performance itself will be performed with sufficient efficiency. Turned out to be difficult.

Therefore, the inventors repeated electromagnetic field simulations and trial production, and as a result of diligently and continuously verifying the wireless power feeding performance and the leaked magnetic field, the magnetic field distribution generated from the coil in the power transmission device and the coil in the power receiving device can receive it. It turned out that there is a technical problem in the direction of the magnetic field. In order to solve this technical problem, the inventors have prepared a power transmission coil in a spiral shape and housed it in a metal housing forming a power transmission device, and made a power reception coil in a spiral or solenoid shape and arranged it in the power reception device. Further, a partition made of glass or plastic as transparent as possible was prepared, and the partition was arranged at each position corresponding to the inner diameter and outer diameter of the spiral power transmission coil with respect to the inside and outside of the partition. As a result, the position where the power receiving device is placed or the range in which the power receiving device can be moved is limited by the inner partition, and the area where people and things can approach is limited to the safe area by the outer partition.

Here, when the power receiving device is a mobile body, if there is a partition as described above, the movement is restricted by the partition, but the time zone (stay time) for moving along the partition is further increased. That is, if the wireless power supply performance is improved in the vicinity of the partition from the surroundings, the power can be supplied to the power receiving device more efficiently. In particular, if the coil in the power receiving device and the coil in the power transmission device are made to face each other, the magnetic flux from the power transmitting coil will more efficiently intersect with the power receiving coil.

The above configuration is not limited to the case where there is one power transmitting device and one power receiving device. For example, a plurality of power receiving devices and a power transmitting device can be arranged, or two power transmitting devices can be prepared and one or a plurality of power receiving devices can be arranged between them. Further, instead of preparing two power transmission devices, by arranging the power transmission device at a position facing the power transmission device with the power receiving device sandwiched by the magnetic shield device, almost the same effect as the above configuration can be obtained.

The partition plate can be arranged so as to maintain the relative relationship with the coil as described above by processing and assembling a transparent plate material or a cylindrical material. For example, two or more partition plates of different sizes can be arranged. It is also possible to use and put various ornaments for exhibition in the meantime.

By performing the above configuration, it has become possible to achieve both the visibility of the exhibition and the prevention of people and objects from approaching the vicinity of a large leakage magnetic field, and it has become possible to sufficiently maintain the wireless power supply performance. We were able to provide a wireless power supply device with high visibility and safety.

It is a figure which shows the outline of the power transmission device (mode 1) of the wireless power supply device of this invention. It is a figure which shows the outline of the power transmission device (mode 2) of the wireless power supply device of this invention. It is a figure which shows the simulation result about the direction of the magnetic field generated from the power transmission device (mode 1) of the wireless power feeding device of this invention. It is a figure which shows the simulation result about the direction of the magnetic field generated from the power transmission device (mode 2) of the wireless power feeding device of this invention. It is a figure which shows the simulation result about the magnitude of the magnetic field generated from the power transmission device (mode 1) of the wireless power feeding device of this invention. It is a figure which shows the simulation result about the magnitude of the magnetic field generated from the power transmission device (mode 2) of the wireless power feeding device of this invention. It is a figure which showed the example of the partition which restricts the arrangement and movement of a power receiving device. It is a figure which showed the example which provided the double partition of this invention in particular among the partitions which restrict the arrangement and movement of a power receiving device. It is a figure which showed the example which mounted two power transmission devices through a partition among the wireless power supply devices of this invention. It is a figure which showed the example which applied this invention to a fish type robot.

The wireless power feeding device of the present invention includes a power transmission device having a power transmission resonator composed of a power transmission coil and a resonance capacitance, and a power reception device having a power reception resonator composed of a power reception coil and a resonance capacity, and includes a power transmission coil and a power reception device. Electric power is transmitted from the power transmitting device to the power receiving device in a non-contact manner by the electromagnetic action between the coils.

In the power receiving device arranged above the power transmission device, the space in which the power receiving device is arranged is partitioned by a transparent material so that the position is limited to a certain area. As a result, the power receiving device can be confined in a position where wireless power can be supplied, and the visibility of the power receiving device from the outside can be enhanced. On the other hand, to prevent people and things from receiving a leakage magnetic field that exceeds the regulations and guidelines, it is necessary to prevent people and things from approaching a certain range of areas near the power transmission device.

Here, the partition limits the position where the power receiving device is arranged or the movable area in the partition so that the magnetic field generated from the power transmitting coil intersects the power receiving coil more efficiently. Specifically, when the inner diameter of the power transmission coil is Rin and the outer diameter is Rout, the partition is arranged inside the position of Rin + (Rout-Rin) / 3 from the center of the coil. However, since the power receiving coil is built in the power receiving device, it is more preferable to consider the positional relationship between the power receiving coil and the power receiving device and the wireless power supply object into which the power receiving device is inserted. That is, when the distance between the outer diameter of the power receiving coil and the outermost side of the power receiving device or the outermost side of the wireless power feeding object is L, the above-mentioned limit position is Rin + (Rout-Rin) / 3 + L from the center of the coil. Further, when the power receiving device is a moving body in particular, it can move freely inside the partition, but when moving inside the partition, the time zone for staying in the vicinity of the partition position increases relatively. Therefore, by improving the wireless power supply performance near the partition position, it is possible to supply power to the power receiving device more efficiently.
<Example>
Hereinafter, more detailed embodiments of the present invention will be described with reference to the drawings with reference to specific examples.

FIG. 1 is a diagram showing an outline of a power transmission device of a wireless power feeding device. It is composed of a coil 100 formed in a plane spiral shape by a litz wire, a ferrite plate 101, and a metal housing 102. Although the input / output unit 103 is outside the metal housing for the convenience of simulation described later, it is possible to arrange a power transmission circuit, a resonance capacitor for a power transmission coil, and the like inside the metal housing. In this embodiment, the inductance is set to 400 to 500 μH by using a 20-turn coil and a ferrite plate made of MnZn, and the capacitance of the capacitor for resonating with this is determined to be the resonance frequency, that is, the transmission frequency selected in this embodiment. The frequency was adjusted to 85 kHz (hereinafter, referred to as mode 1 power transmission device).

FIG. 2 shows a case where two power transmission devices manufactured in the same manner are connected. Since the inductance component is about doubled, the capacitance of the resonance capacitor was selected accordingly and adjusted to the resonance frequency, that is, 85 kHz, which is the transmission frequency (hereinafter, referred to as the power transmission device of mode 2).

Hereinafter, in order to explain the content of the present invention, the description of FIGS. 3 to 6 describes the magnetic field output from the coils of the above mode 1 and mode 2, which are the main components thereof.

FIG. 3 is a diagram showing a simulation result regarding the direction of the magnetic field output from the power transmission device of mode 1. The magnetic field from the power transmission device is an alternating magnetic field of 85 kHz, and the direction of the arrow in the figure indicates the direction of the magnetic field at a certain time. Further, for convenience of explanation, the results of the cross section of the power transmission device shown in FIG. 1 are shown here. Focusing on the state near the bundle of litz wires forming the coil, a magnetic field is generated toward the sky at the inner end face of the bundle of litz wires, and the direction is changed relatively close to the magnetic field to form the coil. Above the center of the bundle of lines, it is almost sideways. Further, the outer end face of the bundle of litz wires forming the coil orbits downward. On the other hand, as a whole, the direction of the magnetic field is relatively aligned toward the sky near the center of the power transmission device. It was found that the threshold value of the above position corresponds to the position of Rin + (Rout-Rin) / 3 from the center of the coil when the inner diameter of the power transmission coil is set to Rin and the outer diameter is set to Rout. However, since the power receiving coil is built in the power receiving device, it is more preferable to consider the positional relationship between the power receiving coil and the power receiving device and the wireless power feeding object into which the power receiving device is inserted. That is, when the distance between the outer diameter of the power receiving coil and the outermost part of the power receiving device or the outermost part of the wireless power feeding object is L, the above-mentioned limit position is Rin + (Rout-Rin) / 3 + L from the center of the coil.

Based on the above results, if the power receiving coil is placed near the inside of the end face of the bundle of litz wires forming the power transmission coil, and the power receiving coil is placed facing the power transmission coil, wireless power feeding is efficient. It turns out that it can be done well. On the contrary, if the power receiving coil is arranged directly above the center of the bundle of litz wires forming the power transmission coil, the magnetic field from the power transmission coil cannot cross the power receiving coil, and the efficiency of wireless power feeding is very poor. It turned out to be. Therefore, it was found that it is necessary to enable the power receiving device to wirelessly supply power with a degree of freedom in arrangement, and to limit the position where the power receiving device is arranged or moved as described above when the power receiving device needs to be moved. ..

FIG. 4 is a diagram showing a simulation result regarding the direction of the magnetic field output from the power transmission coil of mode 2. Here, for convenience of explanation, the results in the cross section of the power transmission device shown in FIG. 2 are shown. The state and arrangement of the litz wires forming the coil near the bundle are as described above. What is characteristic of this mode 2 is the direction of the magnetic field near the center of both power transmission coils and above them, and compared to the case of mode 1, the magnetic field is generated up to the sky more perpendicular to the coil surface. It turned out. That is, it was found that the power transmission coil of mode 2 is more suitable for transmitting wireless power supply to the power receiving coil.

FIG. 5 is a diagram showing simulation results regarding the magnitude of the magnetic field output from the coil of mode 1. Here, the current flowing through the coil was set to 0.5 A. The numbers shown in the figure are numbers showing the magnitude of the magnetic field in microtesla (μT), and the range is indicated by contour lines. From the figure, it became clear that a larger magnetic field was generated as it was closer to the bundle of litz wires forming the coil.

The number shown here as 27 (μT) is a guideline value specified by the International Commission on Non-Ionizing Radiation (ICNIRP), and generally a guideline is issued so that the human body does not receive a magnetic field of a larger value than this. .. That is, it is necessary to keep the magnetic field (exposure of the magnetic field to the human body) exposed to the human body low by preventing the human body from entering the region indicated by 27 by some method. At the same time, when something other than the original power receiving target (for example, a metal such as a nail) exists in the vicinity of the power transmission device, it must be prevented from being overheated by the magnetic field leaked from the power transmission coil.

FIG. 6 shows the result of similarly simulating the magnitude of the magnetic field output from the coil of mode 2. Here, the current flowing through the coil was set to 0.5 A in the same manner. By arranging two power transmission devices facing each other as shown in FIG. 6, it is possible to prevent a human body from intervening due to the structure of itself. From the figure, it is the same as in the case of the coil of mode 1 that a larger magnetic field is generated as it is closer to the bundle of litz wires forming the coil, but further, a magnetic field generated outside between the power transmission devices (hereinafter unnecessary leakage). It was found that a region where a relatively strong magnetic field is generated can be effectively created between power transmission devices without increasing the magnetic field (called a magnetic field). Instead of preparing two power transmission devices, one of the power transmission devices can be a magnetic shield. The magnetic shield is configured by arranging a metal having high conductivity such as aluminum or copper, or arranging a material having high magnetic permeability such as a ferrite plate. If a device that limits the unnecessary leakage magnetic field as described above can be placed on the power transmission device, it is possible to bring about an effect that a person or a metal other than the power receiving target does not approach the power transmission device.

FIG. 7 is a partition arranged to consider the exposure of the magnetic field to the human body by the unnecessary leaking magnetic field and the wireless power feeding performance, and to maintain visibility from the outside. The above two problems can be solved by making a box-shaped partition from glass or a transparent plastic material as shown in the figure and arranging it above the power transmission device. That is, since the visibility from the outside is high and the situation in which the power receiving device is actually receiving wireless power supply can be visually confirmed, it is particularly useful when the power receiving device is, for example, a mannequin or a robot for exhibition. However, as described in the explanations of FIGS. 3 and 4, when the power receiving coil of the power receiving device is arranged or moved near the center of the bundle of litz wires forming the power transmission coil, The problem is that the wireless power supply performance deteriorates at once.

In order to solve the above problems, FIG. 8 is a configuration in which an additional partition is provided in the structure shown in FIG. 7 in consideration of the direction of the magnetic field from the power transmission device. That is, the power receiving device is arranged inside the partition by the inner partition so that it can be moved. As a result, it is possible to efficiently supply wireless power without worrying about the direction of the magnetic field generated from the power transmission coil. Furthermore, the outer partition prevents the metal other than the human body and the object to receive power from being exposed to a certain magnetic field. Since the partition can be made of a transparent material, the state of the power receiving device can be visually recognized from outside the partition.

FIG. 9 shows a wireless power supply device assembled by combining the above methods. That is, two power transmission devices are prepared, and a transparent partition with a double partition between them (in this example, a box whose overall width is larger than that of the power transmission device based on the simulation result) is appropriately provided as described above. Placed. In addition, the power receiving device can be freely arranged inside the partition and can be moved. Here, in order to demonstrate the effect of the present invention, when the apparatus of the present invention was prepared and the alternating magnetic field was actually measured, it was found that the ambient magnetic field could be 27 μT.

As a result, the influence of the unnecessary leaking magnetic field can be reduced without degrading the wireless power supply performance, so that the state of the power receiving device can be visually recognized from the outside of the wireless power supply device without worrying about exposure to the magnetic field of the human body or overheating of metal foreign matter. I can now do it.

Here, in general, the power transmission distance becomes longer when the magnetic field resonance method is used, but according to the study by the inventors, the power transmission distance should be extended even by the magnetic field resonance method, especially when the size of the power receiving coil is small. Is known to be difficult. Therefore, assuming that power transmission is mainly performed by a magnetic field, and considering the relationship between the output magnetic field from the transmission coil and the power receiving coil that receives the magnetic field, the power transmission coil is wound relatively densely around the coil in a plane spiral shape. It was more preferable that the power receiving coil was formed in a solenoid shape. Further, it is preferable that the power transmitting coil and the power receiving coil face each other as much as possible, and the power receiving device or the power receiving object including the power receiving coil is arranged near the partition or stays near the partition for a relatively long time. It was effective in the case.

In the main application of the present invention, the power receiving device is installed in a mannequin or a robot displayed in a show window, and it is preferable to have the above configuration also in that case. FIG. 10 shows a case where, for example, a fish-shaped robot is used as an exhibit. The fish-shaped robot had a power receiving device equipped with a solenoid-shaped power receiving coil built into the robot, and was operated wirelessly by receiving the power of the power transmitting device equipped with a spiral power transmitting coil. The partition fills the inside with water, and the fish-shaped robot migrates in it, but by keeping the weight balance of the power receiving device properly, it is possible to migrate in the water tank so that the power transmitting coil and the power receiving coil always face each other. it can. Even if the fish-shaped robot moves randomly, it can spend a relatively long time in a position where it receives a particularly strong magnetic field from a power transmission coil near the partition.

Therefore, as described above, even if the fish-shaped robot is small and the power receiving coil is small, it is possible to receive sufficient power to move around in the water tank.

The wireless power feeding device of the present invention can minimize an effective unnecessary leakage magnetic field without deteriorating the wireless power feeding performance. Therefore, it is essentially intended to be shown to people such as exhibits and show windows, and can be effectively used when wireless power supply is applied to a form for attracting people.

100 Power transmission coil 101 Ferrite plate 102 Housing 103 Power transmission coil input / output 104 Power transmission coil connection line 200 Power transmission device 201 Power receiving device 202 Partition

Claims (6)

A power transmission device having a power transmission resonator composed of a power transmission coil and a resonance capacitance,
It is equipped with a power receiving device having a power receiving resonator composed of a power receiving coil and a resonance capacitance.
A wireless power feeding device that transmits power from the power transmitting device to the power receiving device in a non-contact manner via an electric or magnetic action between the power transmitting coil and the power receiving coil.
It has a power receiving area surrounded by a transparent partition.
The transparent partition is composed of an inner partition and an outer partition surrounding the inner partition, and the power receiving area is a region surrounded by the inner partition.
The power receiving device is arranged in the power receiving area, and the power transmitting device is arranged outside the power receiving area.
The power receiving device is a wireless power feeding device characterized in that it can be moved within the power receiving region.
When the inner diameter of the power transmission coil is R in and the outer diameter is R ut, the above is inside the position of R in + (R ut − R in) / 3 from the position of the center of gravity of the power transmission coil. The wireless power supply device according to claim 1 , wherein an inner partition is arranged.
When the distance between the outer diameter of the power receiving coil and the outermost part of the power receiving device or the outermost part of the wireless power supply object is L, it is inside R in + (Rout − R in) / 3 + L. The wireless power supply device according to claim 2 , wherein the inner partition is arranged on the inside.
The wireless power supply device according to any one of claims 1 to 3 , wherein the power transmission device is arranged on both ends of the power receiving region via the transparent partition.
The power transmission device is arranged on one end face side of the power receiving region via the transparent partition, and a magnetic shield is arranged on the other end face side of the power receiving region via the transparent partition. The wireless power supply device according to any one of claims 1 to 3 .
The wireless power feeding device according to any one of claims 1 to 5 , wherein the power receiving coil and the power transmitting coil are opposed to each other while maintaining the balance of the power receiving device.

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