Wireless power supply apparatus and wireless power transmission system

Abstract

A wireless power supply apparatus 1A comprises: a housing 10 in which the entirety of an internal space is surrounded by a conductive electromagnetic shielding member; and a plurality of power transmitters 20 that supply power to the internal space of the housing 10. The plurality of power transmitters 20 are arranged such that the respective leading ends thereof are positioned apart from each other. The present invention is configured such that: electromagnetic field distributions having different center positions are respectively formed in the internal space of the housing 10 by the plurality of power transmitters 20; and the electromagnetic field distributions are synthesized so as to form a synthesized electromagnetic field distribution in which a region for strengthening the electromagnetic field and a region for weakening the electromagnetic field are adjacent to each other.

Description

Wireless power supply device and wireless power transmission system

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

[0002] In recent years, with the increase in IoT (Internet of Things) devices, power supply via wired connections has become impractical, and thus technologies for wirelessly transmitting power and systems using such technologies are expected.

[0003] As an example of a wireless power transmission system, a system is known in which electromagnetic waves are incident to excite a predetermined resonance frequency in a metal-enclosed cavity resonator, a device (product) having a charging function is placed inside the cavity resonator, and power is transmitted to the device. A predetermined resonance mode excited at the predetermined resonance frequency inside the cavity resonator couples with a power receiving antenna (power receiver) in the device arranged at a fixed position, whereby the device can be charged with high power receiving efficiency.

[0004] Amid demands for low power consumption, achieving higher power receiving efficiency leads to fast charging of many devices with as little energy as possible, but to achieve higher power receiving efficiency, the devices need to be placed at fixed positions. It is known that in the resonance state inside a cavity resonator, there are portions with large electromagnetic fields (antinodes) and portions with small electromagnetic fields (nodes). To achieve higher power receiving efficiency, it is necessary to satisfy the two conditions shown in the following (1) and (2). (1) A device having a charging function (hereinafter also simply referred to as a charging device) is arranged at a position that is an antinode, which is a portion with a large electric field. (2) The direction of the electric lines of force of the resonance mode matches the direction of the electric field component of the power receiving antenna.

[0005] As described above, since the arrangement positions of the devices are limited to satisfy the above conditions (1) and (2), there is a concern that this will increase the man-hours and costs for workers.

[0006] Non-Patent Document 1 discloses a configuration in which a plurality of IoT devices are arranged in a rectangular housing, and power is supplied to the IoT devices using a resonance mode having a predetermined electromagnetic field distribution.

[0007] Patent Document 1 discloses a configuration in which a resonant mode that results in a predetermined electromagnetic field distribution is excited within a rectangular parallelepiped housing, and power is supplied from a power receiving probe.

[0008] Patent Document 2 describes a resonant mode excited within a rectangular parallelepiped-shaped resonator as TE ｍｎｐ The mode is described.

[0009] U.S. Patent No. 10,707,685, International Publication No. 2022 / 168401

[0010] Rahimizadeh et al. , “Scalable adaptive wireless powering of multiple electronic devices in an over-moded cavity”2013 IEEE Wireless Power Transfer (WPT)

[0011] Non-patent document 1, patent document 1, and patent document 2 all disclose configurations where there is only one power transmitter. In this case, the resonance mode excited within the cavity resonator is determined by the electromagnetic field distribution formed by the single power transmitter and the inherent resonance mode of the cavity resonator, thus limiting the means for controlling the resonance mode within the cavity resonator. As a result, the arrangement of charging devices that can achieve high power reception efficiency is limited.

[0012] The present invention was made to solve the above problems and aims to provide a wireless power supply device that can achieve high power reception efficiency without complicating the structure of the cavity resonator by controlling the resonance mode within the cavity resonator. Furthermore, the present invention aims to provide a wireless power transmission system equipped with the above wireless power supply device.

[0013] The wireless power supply device of the present invention comprises a housing that encloses the entire internal space with a conductive electromagnetic wave shielding member, and a plurality of transmitters that supply power to the internal space of the housing.

[0014] In the wireless power supply device of the present invention, in the first embodiment, the plurality of transmitters are arranged such that the positions of their respective tips are spaced apart from each other. The plurality of transmitters each form electromagnetic field distributions with different center positions in the internal space of the housing, and these electromagnetic field distributions are combined to form a composite electromagnetic field distribution in which regions that reinforce electromagnetic fields and regions that weaken electromagnetic fields are adjacent to each other.

[0015] In the wireless power supply device of the present invention, in a second embodiment, the plurality of transmitters are arranged such that the positions of their respective tips are spaced apart from each other. The plurality of transmitters are configured to receive high-frequency signals having the same amplitude and phase.

[0016] The wireless power transmission system of the present invention comprises the wireless power supply device and a power receiver disposed in the internal space of the housing of the wireless power supply device.

[0017] According to the present invention, by controlling the resonance mode within the cavity resonator, it is possible to provide a wireless power supply device that can achieve high power reception efficiency without complicating the structure of the cavity resonator. Furthermore, according to the present invention, it is possible to provide a wireless power transmission system equipped with the above-mentioned wireless power supply device.

[0018] Figure 1A is a schematic overall diagram showing Embodiment 1-1 of the wireless power supply device according to the first embodiment of the present invention. Figure 1B is a schematic diagram showing an example of the magnetic field distribution formed when the wireless power supply device shown in Figure 1A is viewed from above. Figure 2A is a schematic overall diagram showing Embodiment 1-2 of the wireless power supply device according to the first embodiment of the present invention. Figure 2B is a schematic diagram showing an example of the magnetic field distribution formed when the wireless power supply device shown in Figure 2A is viewed from above. Figure 3A is a schematic overall diagram showing Embodiment 1-3 of the wireless power supply device according to the first embodiment of the present invention. Figure 3B is a schematic diagram showing an example of the magnetic field distribution formed when the wireless power supply device shown in Figure 3A is viewed from above. Figure 4 is a schematic diagram showing an example of a composite magnetic field distribution combined from the magnetic field distributions formed by each transmitter. Figure 5A is a schematic overall diagram showing Embodiment 1-4 of the wireless power supply device according to the first embodiment of the present invention. Figure 5B is a schematic diagram showing an example of the magnetic field distribution formed when the wireless power supply device shown in Figure 5A is viewed from above. Figure 6 is a schematic overall diagram showing Embodiment 1-5 of the wireless power supply device according to the first embodiment of the present invention. Figure 7 is a schematic overall diagram showing a first modified example of Embodiment 1-5 of the wireless power supply device according to the first embodiment of the present invention. Figure 8 is a schematic overall diagram showing a second modified example of Embodiment 1-5 of the wireless power supply device according to the first embodiment of the present invention. Figure 9 is a schematic overall diagram showing Embodiment 1-6 of the wireless power supply device according to the first embodiment of the present invention. Figure 10 is a schematic overall diagram showing Embodiment 1-7 of the wireless power supply device according to the first embodiment of the present invention. Figure 11 is a schematic overall diagram showing Embodiment 2-1 of the wireless power supply device according to the second embodiment of the present invention. Figure 12 is a schematic overall diagram showing Embodiment 2-2 of the wireless power supply device according to the second embodiment of the present invention. Figure 13 is a schematic overall diagram showing Embodiment 2-3 of the wireless power supply device according to the second embodiment of the present invention. Figure 14A is a schematic overall diagram showing Embodiment 3-1 of the wireless power supply device according to the third embodiment of the present invention. Figure 14B is a top view of the wireless power supply device shown in Figure 14A. Figure 15A is a schematic overall diagram showing a first modified example of Embodiment 3-1 of the wireless power supply device according to the third embodiment of the present invention.Figure 15B is a top view of the wireless power supply device shown in Figure 15A. Figure 16A is a schematic overall diagram illustrating a second modification of Example 3-1 of the wireless power supply device according to the third embodiment of the present invention. Figure 16B is a top view of the wireless power supply device shown in Figure 16A. Figure 17A is a schematic overall diagram illustrating Example 3-2 of the wireless power supply device according to the third embodiment of the present invention. Figure 17B is a top view of the wireless power supply device shown in Figure 17A. Figures 18A and 18B are schematic overall diagrams illustrating Example 3-3 of the wireless power supply device according to the third embodiment of the present invention. Figure 19 is a schematic overall diagram illustrating Example 4-1 of the wireless power supply device according to the fourth embodiment of the present invention. Figure 20 is a schematic diagram showing an example of the magnetic field distribution formed when the wireless power supply device shown in Figure 19 is viewed from above. Figure 21A is a schematic diagram of the magnetic field distribution of Example 4-1. Figure 21B is a schematic diagram of the magnetic field distribution of Comparative Example 4-1. Figure 22A shows the simulation results for Example 4-1. Figure 22B shows the simulation results for Comparative Example 4-1. Figure 23A is a schematic diagram showing an example of the relative positional relationship when a guide such as a helmet equipped with a charging device is placed on the simulation results for Example 4-1 shown in Figure 22A. Figure 23B is a schematic diagram showing an example of the relative positional relationship when a guide such as a helmet equipped with a charging device is placed on the simulation results for Comparative Example 4-1 shown in Figure 23A. Figure 24A is a schematic overall diagram showing an example of a wireless power supply device according to the fifth embodiment of the present invention. Figure 24B is a top view of the wireless power supply device shown in Figure 24A. Figure 25A is a schematic diagram showing an example of a magnetic field vector formed from a coaxial probe when a / b = 0.3. Figure 25B is a schematic diagram showing an example of a high-power-receivable region considering the electromagnetic field cancellation region in Figure 25A. Figure 26A is a schematic diagram showing an example of a magnetic field vector formed from a coaxial probe when a / b = 0.5. Figure 26B is a schematic diagram showing an example of a high-power reception region in Figure 26A, taking into account the electromagnetic field cancellation region. Figure 27A is a schematic diagram showing an example of a magnetic field vector formed from a coaxial probe when a / b = 0.7. Figure 27B is a schematic diagram showing an example of a high-power reception region in Figure 27A, taking into account the electromagnetic field cancellation region.Figure 28 is a schematic diagram illustrating the position of the power transmitters. Figure 29 is a schematic diagram showing the first example of the magnetic field distribution when the amplitude of the high-frequency signal input to each power transmitter is controlled. Figure 30 is a schematic diagram showing the second example of the magnetic field distribution when the amplitude of the high-frequency signal input to each power transmitter is controlled. Figure 31 is a schematic diagram showing the third example of the magnetic field distribution when the amplitude of the high-frequency signal input to each power transmitter is controlled. Figure 32 is a schematic diagram showing the first example of the magnetic field distribution when the phase of the high-frequency signal input to each power transmitter is controlled. Figure 33 is a schematic diagram showing the second example of the magnetic field distribution when the phase of the high-frequency signal input to each power transmitter is controlled. Figure 34 is a schematic diagram showing the third example of the magnetic field distribution when the phase of the high-frequency signal input to each power transmitter is controlled. Figure 35 is a schematic diagram showing the fourth example of the magnetic field distribution when the phase of the high-frequency signal input to each power transmitter is controlled. Figure 36 is a schematic diagram showing the fifth example of the magnetic field distribution when the phase of the high-frequency signal input to each power transmitter is controlled.

[0019] The wireless power supply device of the present invention will be described below. However, the present invention is not limited to the following embodiments and can be modified and applied as appropriate without altering the essence of the invention. Furthermore, a combination of two or more of the preferred configurations described in the following embodiments also constitutes the present invention.

[0020] Generally, in cavity resonant wireless power transfer devices, the electromagnetic field formed by the transmitter couples with the intrinsic resonant modes of the cavity resonator, thereby exciting resonant modes within the cavity resonator. In other words, not all of the intrinsic resonant modes within the cavity resonator are excited; rather, the electromagnetic field formed by the transmitter strongly couples with the resonant modes that have a high coupling coefficient.

[0021] The inventors hypothesized that if the electromagnetic field distribution formed by a power transmitter could be controlled to strongly couple with a desired resonant mode within a cavity resonator, it might be possible to improve power reception efficiency without complicating the structure of the cavity resonator. This invention relates to a method for controlling the resonant mode within a cavity resonator by controlling the electromagnetic field formed by a power transmitter.

[0022] The wireless power supply device of the present invention is configured to wirelessly supply power to a device via a receiver using a transmitter. Thus, a wireless power transmission system comprising the wireless power supply device and receiver of the present invention is also one of the present inventions.

[0023] The embodiments described below are illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. In the second and subsequent embodiments, descriptions of matters common to the first embodiment will be omitted, and only the differences will be explained. In particular, similar effects and advantages due to similar configurations will not be mentioned sequentially for each embodiment.

[0024] In the following description, unless otherwise specified, each embodiment will simply be referred to as "the wireless power supply device of the present invention."

[0025] In this specification, terms describing relationships between elements (e.g., "symmetrical," "perpendicular," "parallel," "orthogonal," etc.) and terms describing the shapes of elements (e.g., "circular," "regular polygonal," etc.) do not necessarily represent only strict meanings, but also include a range of substantially equivalent values, such as differences of a few percent. Furthermore, in this specification, "identical" does not necessarily mean exactly the same, but rather means substantially identical, including differences of a few percent.

[0026] The following diagrams are schematic representations, and their dimensions, aspect ratios, and scales may differ from those of the actual product. The same reference numerals are used for identical or equivalent parts in the diagrams. Furthermore, identical elements are denoted by the same reference numerals in each diagram, and redundant explanations are omitted.

[0027] [First Embodiment] Figure 1A is a schematic overall diagram showing Embodiment 1-1 of the wireless power supply device according to the first embodiment of the present invention. Figure 1B is a schematic diagram showing an example of the magnetic field distribution formed when the wireless power supply device shown in Figure 1A is viewed from above. In Figure 1B, the magnetic field distribution is shown as an example of the electromagnetic field distribution. The same applies to subsequent embodiments.

[0028] The wireless power supply device 1A shown in Figure 1A comprises a housing 10 and a plurality of transmitters 20 that supply power to the internal space of the housing 10. In a wireless power transmission system equipped with the wireless power supply device 1A shown in Figure 1A, a power receiver (not shown) is placed in the internal space of the housing 10. For example, the power receiver is provided in a device that has a charging function.

[0029] The enclosure 10 is completely surrounded by a conductive electromagnetic wave shielding member.

[0030] The housing 10 has, for example, a bottom portion 10a, a top portion 10b facing the bottom portion 10a, and a side portion 10c connecting the bottom portion 10a and the top portion 10b. The bottom portion 10a is, for example, a planar surface (i.e., a bottom surface). The top portion 10b may be, for example, a planar surface (i.e., a top surface) or a point (i.e., a vertex).

[0031] In the example shown in Figure 1A, the housing 10 has a rectangular (or square) shape with a rectangular base and a square top. The shape of the housing 10 is not limited to a rectangular shape; for example, it may be a pentagonal prism with a pentagonal base and a square top, a rectangular prism with a trapezoidal base and a square top, a cylindrical shape with a circular base and a square top, a semi-cylindrical shape with a semicircle base and a square top, etc. The shape of the housing 10 may also be a hemispherical shape with a circular base, etc.

[0032] The material of the electromagnetic wave shielding member is not particularly limited as long as it is conductive, but preferably metal materials such as copper, aluminum, iron, stainless steel, and nickel are used. Alternatively, conductive oxide materials such as zinc oxide, titanium oxide, and indium tin oxide (ITO), graphite, and organic conductive materials are used. Furthermore, the material of the electromagnetic wave shielding member may be an alloy or mixture as long as it is conductive. The electromagnetic wave shielding member may have a multilayer structure made of these materials. Among these, materials with high conductivity and low magnetic permeability are desirable for the electromagnetic wave shielding member, and specifically, metal materials such as copper, aluminum, and non-magnetic stainless steel (non-magnetic SUS) are desirable.

[0033] Electromagnetic wave shielding members may take any shape, such as a plate, mesh, film, or porous form, as long as they shield electromagnetic waves at the power supply frequency. Furthermore, electromagnetic wave shielding members may be covered with an electromagnetic wave-transmitting material for surface protection or other purposes. Note that electromagnetic wave shielding by the electromagnetic wave shielding member only needs to shield electromagnetic waves at the frequency used for wireless power transmission. In other words, it is possible to use the member without shielding against communication at frequencies different from those used for wireless power transmission.

[0034] Multiple power transmitters 20 are arranged so that the positions of their respective ends are spaced apart from each other.

[0035] In the wireless power supply device 1A shown in Figure 1A, a coaxial probe 21 and a waveguide 22 are arranged on the upper surface of the housing 10 as the transmitter 20.

[0036] Figure 2A is a schematic overall diagram showing Embodiment 1-2 of the wireless power supply device according to the first embodiment of the present invention. Figure 2B is a schematic diagram showing an example of the magnetic field distribution formed when the wireless power supply device shown in Figure 2A is viewed from above.

[0037] In the wireless power supply device 1B shown in Figure 2A, the transmitter 20 consists of a coaxial probe 21 and a dielectric substrate antenna 23, which has electrodes patterned on a dielectric substrate, arranged on the upper surface of the housing 10.

[0038] Figure 3A is a schematic overall diagram showing three embodiments of a wireless power supply device according to the first embodiment of the present invention. Figure 3B is a schematic diagram showing an example of the magnetic field distribution formed when the wireless power supply device shown in Figure 3A is viewed from above.

[0039] In the wireless power supply device 1C shown in Figure 3A, the transmitter 20 consists of a coaxial probe 21 and a loop antenna 24 from a coaxial cable, which are arranged on the top surface of the housing 10.

[0040] In the wireless power supply device 1A shown in FIG. 1A, the wireless power supply device 1B shown in FIG. 2A, and the wireless power supply device 1C shown in FIG. 3A, a plurality of power transmitters respectively form electromagnetic field distributions with different center positions in the internal space of the housing, and the electromagnetic field distributions are combined to form a combined electromagnetic field distribution.

[0041] In the examples shown in FIG. 1B, FIG. 2B and FIG. 3B, the combination of magnetic field distributions will be described, but the same applies when focusing on electric field distributions. The same applies to the subsequent examples.

[0042] As shown in FIG. 1B, FIG. 2B and FIG. 3B, the magnetic field distributions formed by each of the power transmitters 20 (the direction of each magnetic field vector is indicated by an arrow in FIG. 1B, FIG. 2B and FIG. 3B) are different, and various electromagnetic field distributions can be controlled by combining these magnetic field distributions.

[0043] FIG. 4 is a schematic diagram showing an example of a combined magnetic field distribution that is combined with the magnetic field distribution formed by each power transmitter. FIG. 4 shows the combined magnetic field distribution in the configuration of Examples 1 to 3.

[0044] FIG. 4 shows the magnetic field vectors (magnetic force lines) respectively formed by the coaxial probe 21 and the loop antenna 24. As shown in FIG. 4, at locations where the directions of the magnetic field vectors respectively formed by the coaxial probe 21 and the loop antenna 24 are substantially the same, the magnetic fields reinforce each other and the intensity increases. On the other hand, at locations where the directions of the magnetic field vectors are substantially opposite, the magnetic fields cancel each other out, so the magnetic fields weaken each other and the intensity decreases. As a result, a combined magnetic field distribution is formed in which the region RS where the magnetic fields reinforce each other and the region RW where the magnetic fields weaken each other are adjacent to each other. This combined magnetic field region can be controlled by the arrangement of the coaxial probe 21 and the loop antenna 24.

[0045] As described above, the same applies not only to the combination of magnetic field distributions but also to the combination of electric field distributions. As described above, in the wireless power supply device of the present invention, a plurality of power transmitters respectively form electromagnetic field distributions with different center positions in the internal space of the housing, and the electromagnetic field distributions are combined, so that a combined electromagnetic field distribution in which a region where electromagnetic fields reinforce each other and a region where electromagnetic fields weaken each other are adjacent to each other is formed.

[0046] In the wireless power supply device of the present invention, a configuration may be adopted in which high-frequency signals having the same amplitude and phase across each power transmitter are input to the plurality of power transmitters. Alternatively, a configuration may be adopted in which high-frequency signals, of which at least one of the amplitude and the phase differs in some or all of the power transmitters, are input to the plurality of power transmitters.

[0047] In the wireless power supply device of the present invention, it is preferable that the plurality of power transmitters are led out from the same wall surface of the housing. In the examples shown in FIG. 1A, FIG. 2A and FIG. 3A, the plurality of power transmitters 20 are led out from the upper surface of the housing 10.

[0048] FIG. 5A is a schematic overall diagram schematically illustrating Examples 1 to 4 of the wireless power supply device according to the first embodiment of the present invention. FIG. 5B is a schematic diagram illustrating an example of a magnetic field distribution formed when the wireless power supply device shown in FIG. 5A is viewed from the upper surface.

[0049] The wireless power supply device 1D shown in FIG. 5A differs in the direction of the loop antenna 24 compared with the wireless power supply device 1C shown in FIG. 3A. Also in this case, the power transmitter 20 can be arranged from the upper surface of the housing 10 by bending the coaxial cable by 90° for arrangement.

[0050] For example, in Examples 1-1 to 1-4, the shape of each power transmitter 20 is set as follows. ・Coaxial probe 21: The distal end of the inner conductor of the coaxial cable defined by a characteristic impedance of 50 Ω is protruded. Impedance matching with the impedance inside the housing is achieved by the protrusion amount. ・Waveguide 22: The cross-sectional shape is set to a dimension that allows a high-frequency signal of a predetermined frequency to propagate. As an example, in the case of 2.45 GHz, the dimension is 86.36×43.18 mm. ・Dielectric substrate antenna 23: The dimension of the electrode that enables impedance matching inside the cavity resonator is set. ・Loop antenna 24: The diameter of the loop that enables impedance matching inside the cavity resonator is set.

[0051] Figure 6 is a schematic overall diagram showing Embodiments 1-5 of the wireless power supply device according to the first embodiment of the present invention. Figure 7 is a schematic overall diagram showing a first modified example of Embodiments 1-5 of the wireless power supply device according to the first embodiment of the present invention. Figure 8 is a schematic overall diagram showing a second modified example of Embodiments 1-5 of the wireless power supply device according to the first embodiment of the present invention.

[0052] A door 30 may be provided on one side of the housing 10, as shown in the wireless power supply device 1E in Figure 6, the wireless power supply device 1Ea in Figure 7, and the wireless power supply device 1Eb in Figure 8. In the examples shown in Figures 6, 7, and 8, the door 30 is provided on the side of the housing 10, and it is preferable that a plurality of power transmitters 20 are arranged on one side of the housing 10 other than the door 30.

[0053] In the wireless power supply device 1E shown in Figure 6, a total of four components are arranged as the transmitter 20: a coaxial probe 21, a waveguide 22, and a loop antenna 24.

[0054] In the wireless power supply device 1Ea shown in Figure 7, a total of two transmitters 20 are arranged: a coaxial probe 21 and a dielectric substrate antenna 23.

[0055] In the wireless power supply device 1Eb shown in Figure 8, a total of four components are arranged as the transmitter 20: a coaxial probe 21 and a loop antenna 24.

[0056] Figure 9 is a schematic overall diagram showing Embodiment 1-6 of the wireless power supply device according to the first embodiment of the present invention.

[0057] For example, by arranging multiple power transmitters 20 on the surface of the housing 10 facing the door 30, it becomes possible to stack multiple housings 10 in at least one direction, both vertically and horizontally, as shown in the wireless power supply device 1F in Figure 9. Therefore, in Embodiments 1-6, the housings 10 can be arranged efficiently.

[0058] Figure 10 is a schematic overall diagram showing Embodiment 1-7 of the wireless power supply device according to the first embodiment of the present invention.

[0059] As shown in Figure 10, the wireless power supply device 1G may have multiple transmitters 20 covered by cover members 35 such as resin caps. The shape of the cover member 35 is not particularly limited, but it is desirable that it be configured with a curved shape having an appropriate curved portion (R portion) so as not to disturb the electromagnetic field distribution formed by the transmitters 20.

[0060] In the example shown in Figure 10, four power transmitters 20 are arranged on the top surface of the housing 10, and a cover member 35 is provided inside the housing 10 to cover these power transmitters 20.

[0061] The material of the cover member 35 is not particularly limited as long as it transmits electromagnetic waves of a predetermined frequency and has a small dielectric loss tangent, but a resin material is preferred. Examples of resin materials include polymethyl methacrylate (PMMA, acrylic) and polycarbonate (PC). It is desirable that the cover member 35 be immovable, and a thickness appropriate to the strength of each material is required.

[0062] In the example shown in Figure 10, multiple power transmitters 20 are covered by a single cover member 35, but the configuration of the cover member 35 is not limited to this. For example, each power transmitter 20 may be covered by a separate cover member 35. Also, among the multiple power transmitters 20, there may be some that are not covered by the cover member 35. That is, at least one of the multiple power transmitters 20 may be covered by the cover member 35.

[0063] In Examples 1-7, the cover member 35 prevents short circuits caused by contact with the charging device placed inside the housing 10, thereby improving safety. Furthermore, when the charging device is placed inside the housing 10, the cover member 35 protects the transmitter 20, thus preventing damage to the transmitter 20.

[0064] [Second Embodiment] In the wireless power supply device according to the second embodiment of the present invention, the tips of multiple transmitters are located on the same virtual plane. Preferably, each of the multiple transmitters has the same shape.

[0065] Figure 11 is a schematic overall diagram showing Example 2-1 of the wireless power supply device according to the second embodiment of the present invention. Figure 12 is a schematic overall diagram showing Example 2-2 of the wireless power supply device according to the second embodiment of the present invention. Figure 13 is a schematic overall diagram showing Example 2-3 of the wireless power supply device according to the second embodiment of the present invention.

[0066] In the wireless power supply device 2A shown in Figure 11, the wireless power supply device 2B shown in Figure 12, and the wireless power supply device 2C shown in Figure 13, the tips of the multiple transmitters 20 are located on the same virtual plane. The virtual plane on which the tips of the multiple transmitters 20 are located may or may not be parallel to the bottom or top surface of the housing 10.

[0067] As shown in Figures 11, 12, and 13, it is preferable that the multiple power transmitters 20 each have the same shape.

[0068] In the wireless power supply device 2A shown in Figure 11, two waveguides 22 are arranged on the upper surface of the housing 10.

[0069] In the wireless power supply device 2B shown in Figure 12, two dielectric substrate antennas 23, each with electrodes patterned on a dielectric substrate, are arranged on the side of the housing 10, connected to two coaxial cables.

[0070] In the wireless power supply device 2C shown in Figure 13, a loop antenna 24 is mounted on the side of the housing 10, connected to two coaxial cables.

[0071] As in the wireless power supply device according to the second embodiment of the present invention, if the electromagnetic field distribution formed by each transmitter is the same, and the tips of each transmitter are arranged on the same virtual plane, mode synthesis becomes easier, and various modes of control become possible.

[0072] [Third Embodiment] In the wireless power supply device according to the third embodiment of the present invention, the tips of a plurality of power transmitters are arranged symmetrically with respect to the center of the housing.

[0073] In this specification, "center of the enclosure" is defined as "the center of gravity of one side of the enclosure."

[0074] Figure 14A is a schematic overall diagram showing Embodiment 3-1 of the wireless power supply device according to the third embodiment of the present invention. Figure 14B is a top view of the wireless power supply device shown in Figure 14A. Figure 15A is a schematic overall diagram showing a first modified example of Embodiment 3-1 of the wireless power supply device according to the third embodiment of the present invention. Figure 15B is a top view of the wireless power supply device shown in Figure 15A. Figure 16A is a schematic overall diagram showing a second modified example of Embodiment 3-1 of the wireless power supply device according to the third embodiment of the present invention. Figure 16B is a top view of the wireless power supply device shown in Figure 16A.

[0075] In the wireless power supply device 3A shown in Figure 14A, the tips of the two transmitters 20 are positioned symmetrically with respect to the center of the housing 10. As shown in Figure 14B, when the number of transmitters 20 is n=2, the transmitters 20 are positioned at 180° rotational intervals with respect to the center of the housing 10 (indicated by the × mark in Figure 14B).

[0076] In the wireless power supply device 3Aa shown in Figure 15A, the tips of the four transmitters 20 are positioned symmetrically with respect to the center of the housing 10. As shown in Figure 15B, when the number of transmitters 20 is n=4, the transmitters 20 are arranged at 90° rotational intervals with respect to the center of the housing 10 (indicated by the × mark in Figure 15B).

[0077] In the wireless power supply device 3Ab shown in Figure 16A, the tips of the six transmitters 20 are positioned symmetrically with respect to the center of the housing 10. As shown in Figure 16B, when the number of transmitters 20 is n=6, the transmitters 20 are arranged at 60° rotational intervals with respect to the center of the housing 10 (indicated by the × mark in Figure 16B).

[0078] The more transmitters 20 there are (n), the more likely it is to achieve the desired symmetrical resonant mode. Generally, it is desirable for the transmitters 20 to be arranged at rotational intervals of 360 / n° for each transmitter 20 (n).

[0079] The number n of the power transmitters 20 may be even or odd. There is no particular upper limit to the number n of power transmitters 20, as long as they can be physically arranged.

[0080] Figure 17A is a schematic overall diagram showing Embodiment 3-2 of the wireless power supply device according to the third embodiment of the present invention. Figure 17B is a top view of the wireless power supply device shown in Figure 17A.

[0081] Unlike the wireless power supply device 3Aa shown in Figure 15A, the wireless power supply device 3B shown in Figure 17A has a cylindrical housing 10.

[0082] As described above, the shape of the housing 10 is not limited to a rectangular parallelepiped shape, but may also be cylindrical or the like, and any shape in which the center of the housing 10 can be defined can be used.

[0083] Figures 18A and 18B are schematic diagrams illustrating Embodiment 3-3 of the wireless power supply device according to the third embodiment of the present invention. Figure 18A is a perspective view of Figure 18B.

[0084] In the wireless power supply device 3C shown in Figures 18A and 18B, four loop antennas 24 are arranged on the top surface of the housing 10, with the coaxial cable bent at a 90° angle.

[0085] In the wireless power supply device according to the third embodiment of the present invention, a desired rotationally symmetric resonant mode with respect to the central axis can be realized. Therefore, in a configuration in which the charging device is arranged in a rotationally symmetric position, the positional variation of the charging device is reduced, and high power reception efficiency can be achieved.

[0086] Furthermore, since a rotationally symmetric resonant mode is more likely to occur as the number of transmitters n increases, a rotationally symmetric resonant mode can be realized even if the housing has a rectangular parallelepiped shape.

[0087] [Fourth Embodiment] In the wireless power supply device according to the fourth embodiment of the present invention, a high-frequency signal having the same amplitude and phase is input to each of the multiple transmitters.

[0088] Figure 19 is a schematic overall diagram showing an embodiment 4-1 of the wireless power supply device according to the fourth embodiment of the present invention. Figure 20 is a schematic diagram showing an example of the magnetic field distribution formed when the wireless power supply device shown in Figure 19 is viewed from above.

[0089] In the wireless power supply device 4A shown in Figure 19, four transmitters 20 are arranged on the top surface of the housing 10 in a position that is rotationally symmetrical with respect to the center of the housing 10.

[0090] When high-frequency signals with the same amplitude and phase are input to each of these transmitters 20, the following occurs, as shown in Figure 20.

[0091] In the central region indicated by II in Figure 20, when high-frequency signals of the same amplitude and phase are input to each of the four transmitters 20, they cancel each other out with the magnetic fields formed by the opposing transmitters 20, resulting in a region where there is virtually no magnetic field (or a very small magnetic field).

[0092] On the other hand, in the outer region indicated by I in Figure 20, a rotationally symmetric magnetic field distribution is formed. As described above, in the central region indicated by II, the magnetic field is canceled out and does not exist, so the energy is concentrated towards the outer periphery.

[0093] Figure 21A is a schematic diagram of the magnetic field distribution in Example 4-1. Figure 21B is a schematic diagram of the magnetic field distribution in Comparative Example 4-1.

[0094] Figure 21A schematically shows the magnetic field distribution when high-frequency signals with the same amplitude and phase are input to the housing 10 from four transmitters 20, similar to Figure 20. On the other hand, Figure 21B schematically shows the magnetic field distribution when a single transmitter 20 is placed in the center and a high-frequency signal is input to the housing 10 from it, for comparison.

[0095] In Example 4-1, as shown in Figure 21A, the magnetic fields in the central region cancel each other out, resulting in a magnetic field distribution close to the fundamental mode. Using this combined mode makes it easier to excite lower-order rotational axisymmetric resonance modes in the cavity resonator.

[0096] On the other hand, in Comparative Example 4-1, as shown in Figure 21B, when the enclosure size D (length of one side of the base in the case of a rectangular cavity resonator, or diameter in the case of a cylindrical cavity resonator) is larger than the wavelength λ (λ > D), higher-order modes are excited. When these higher-order modes are excited, higher-order rotationally symmetric resonant modes are more easily excited in the cavity resonator, resulting in greater losses.

[0097] Figure 22A shows the simulation results for Example 4-1. Figure 22B shows the simulation results for Comparative Example 4-1. In Figures 22A and 22B, the magnitude of the magnetic field strength is represented by the relative intensity of the contrast.

[0098] As an example of the housing 10, a cylinder with a diameter of 300 mm and a height of 280 mm is used. In Figure 22A, four transmitters 20 are arranged at 90° intervals on a circumference with a radius of 70 mm, while in Figure 22B, one transmitter 20 is placed in the center. Figures 22A and 22B show the magnetic field distribution at 2.43 GHz.

[0099] In Figure 22A, it can be seen that the magnetic field vectors near the center form nodes (due to magnetic field cancellation). Additionally, there is one antinode in the radial direction.

[0100] On the other hand, in Figure 22B, in addition to the node near the center, there are also nodes surrounding the node near the center. Furthermore, it can be seen that there are two antinodes, one near the center and one near the enclosure wall, relative to the node surrounding the node near the center.

[0101] Figure 23A is a schematic diagram showing an example of the relative positional relationship when a guide such as a helmet equipped with a charging device is placed on the simulation results of Example 4-1 shown in Figure 22A. Figure 23B is a schematic diagram showing an example of the relative positional relationship when a guide such as a helmet equipped with a charging device is placed on the simulation results of Comparative Example 4-1 shown in Figure 23A.

[0102] In the example shown in Figure 23A, the charging device 40, which is attached to a guide 45 such as a helmet, is positioned at a location with a high magnetic field strength. Even if the charging device 40 is rotated and attached to the guide 45 such as a helmet, the magnetic field distribution shown in Figure 23A is axially symmetric, so the power reception efficiency does not change. Furthermore, since this mode is a lower-order resonant mode, the region with a high magnetic field strength is large. Therefore, there are fewer constraints on the placement of the charging device to obtain high power reception efficiency, and the position dependence of the power reception efficiency is small.

[0103] On the other hand, in the example shown in Figure 23B, the charging device 40 attached to the guide 45 of a helmet or the like is positioned at a location with low magnetic field strength (a node). In this case, even if the charging device 40 is rotated and attached to the guide 45 of a helmet or the like, the magnetic field distribution shown in Figure 23B is axially symmetric, so the power reception efficiency remains low. Furthermore, this mode is a higher-order mode in which nodes exist. Therefore, the region with high magnetic field strength is small. As a result, there are significant constraints on the placement of the charging device, and the position dependence of the power reception efficiency is large.

[0104] By using the composite mode of the wireless power supply device according to the fourth embodiment of the present invention, lower-order rotational axisymmetric resonance modes are more easily excited in the cavity resonator, enabling lower losses.

[0105] Furthermore, since the electromagnetic field near the center of the enclosure can be reduced, a resonant mode becomes possible in which the electromagnetic field strength increases in the surrounding area.

[0106] In this mode, the region with high electromagnetic field strength is expanded, reducing the positional dependence of power reception efficiency. As a result, the degree of freedom in the placement of charging devices increases.

[0107] [Fifth Embodiment] In the wireless power supply device according to the fifth embodiment of the present invention, when viewing a plane in plan view where the tips of the multiple power transmitters are positioned symmetrically with respect to the center of the housing, the tips of the multiple power transmitters are positioned in an intermediate region between the center of the housing and the wall surface of the housing.

[0108] Figure 24A is a schematic overall view showing an example of a wireless power supply device according to the fifth embodiment of the present invention. Figure 24B is a top view of the wireless power supply device shown in Figure 24A.

[0109] As shown in Figures 24A and 24B, the structure will be described using a configuration where four coaxial probes 21 are arranged on the top surface of a cylindrical housing 10 as a power transmitter 20, and power is supplied with the same amplitude and phase. Specifically, we will consider how the electromagnetic field behaves based on the a / b ratio, where a is the distance from the center of the cylindrical housing 10 (the center of the circle on the top surface in Figure 24B, indicated by the ×), and b is the radius of the circle on the top surface.

[0110] Figure 25A is a schematic diagram showing an example of a magnetic field vector formed from a coaxial probe when a / b = 0.3. Figure 25B is a schematic diagram showing an example of a high-power receivable region in Figure 25A, taking into account the electromagnetic field cancellation region. Figure 26A is a schematic diagram showing an example of a magnetic field vector formed from a coaxial probe when a / b = 0.5. Figure 26B is a schematic diagram showing an example of a high-power receivable region in Figure 26A, taking into account the electromagnetic field cancellation region. Figure 27A is a schematic diagram showing an example of a magnetic field vector formed from a coaxial probe when a / b = 0.7. Figure 27B is a schematic diagram showing an example of a high-power receivable region in Figure 27A, taking into account the electromagnetic field cancellation region. In Figures 25B, 26B, and 27B, the high-power receivable region is indicated by diagonal lines.

[0111] As shown in Figures 26A and 26B, when the coaxial probe 21 is positioned in an intermediate region between the center of the housing 10 and the wall surface of the housing 10, with a / b = 0.5, the sum of the magnetic field vectors formed by each coaxial probe 21 in the central part of the housing 10 will be in opposite directions and will cancel each other out, resulting in a smaller sum.

[0112] On the other hand, as shown in Figures 25A and 25B, when the position of the coaxial probe 21 is close to the center of the housing 10, a / b = 0.3, the magnetic field cancellation region in the central part of the housing 10 becomes smaller. However, when the coaxial probe 21 is placed close to the center of the housing 10, higher-order modes are excited near the walls of the housing 10. As a result, the following node appears, and a magnetic field cancellation region appears even at the walls of the housing 10, thus reducing the high-power reception region.

[0113] Furthermore, as shown in Figures 27A and 27B, when the position of the coaxial probe 21 is close to the wall surface of the housing 10, a / b = 0.7, by arranging the coaxial probes 21 far apart from each other near the wall surface of the housing 10, higher-order modes are excited near the center of the housing 10, and the next node appears in the center, resulting in a magnetic field cancellation region. Also, if the coaxial probe 21 is placed near the wall surface of the housing 10, the magnetic field formed by the wall surface of the housing 10 and the coaxial probe 21 interfere with each other, resulting in increased conductor loss.

[0114] From the above, it can be seen that by positioning the transmitter 20, such as the coaxial probe 21, around a / b = 0.5, the region in which high power reception efficiency can be obtained becomes larger.

[0115] In the wireless power supply device according to the fifth embodiment of the present invention, when the distance from the center of the housing to the transmitter is a and the distance from the center of the housing to the wall surface of the housing is b, a / b is preferably 0.4 or more and 0.6 or less, more preferably 0.45 or more and 0.55 or less, and even more preferably 0.475 or more and 0.525 or less.

[0116] In the wireless power supply device according to the fifth embodiment of the present invention, the region in which high power reception efficiency can be obtained is widened, and the degree of freedom in the arrangement of charging devices is further increased.

[0117] [Sixth Embodiment] In the wireless power supply device according to the sixth embodiment of the present invention, a high-frequency signal is input to a plurality of transmitters, in which at least one of the amplitude and phase differs for some or all of the transmitters. In the following example, the high-frequency signal differs for some or all of the transmitters in terms of amplitude and phase, while the other amplitude and phase are the same for all of the transmitters.

[0118] Figure 28 is a schematic diagram illustrating the location of the power transmitters. In the example shown in Figure 28, the power transmitters are located at the positions marked with circles No. 1, No. 2, No. 3, and No. 4.

[0119] Figure 29 is a schematic diagram showing the first example of the magnetic field distribution when the amplitude of the high-frequency signal input to each power transmitter is controlled. Figure 30 is a schematic diagram showing the second example of the magnetic field distribution when the amplitude of the high-frequency signal input to each power transmitter is controlled. Figure 31 is a schematic diagram showing the third example of the magnetic field distribution when the amplitude of the high-frequency signal input to each power transmitter is controlled. In the examples shown in Figures 29, 30, and 31, the amplitude distribution is set so that the total amplitude is the same.

[0120] As shown in Figures 29 to 31, when the amplitude of the high-frequency signal input to each transmitter is controlled, the following can be observed: • The shape of the rotationally symmetric resonant mode does not change significantly with the amplitude ratio. • Depending on the amplitude ratio, it changes to an elliptical shape, etc., and the position of the nodes changes.

[0121] Figure 32 is a schematic diagram showing the first example of the magnetic field distribution when the phase of the high-frequency signal input to each power transmitter is controlled. Figure 33 is a schematic diagram showing the second example of the magnetic field distribution when the phase of the high-frequency signal input to each power transmitter is controlled. Figure 34 is a schematic diagram showing the third example of the magnetic field distribution when the phase of the high-frequency signal input to each power transmitter is controlled. Figure 35 is a schematic diagram showing the fourth example of the magnetic field distribution when the phase of the high-frequency signal input to each power transmitter is controlled. Figure 36 is a schematic diagram showing the fifth example of the magnetic field distribution when the phase of the high-frequency signal input to each power transmitter is controlled.

[0122] As shown in Figures 32 to 36, when the phase of the high-frequency signal input to each transmitter is controlled, the following can be observed: • Changing only one of the four phase differences input to the transmitter does not significantly change the shape of the rotationally symmetric resonant mode. • Changing two or more phase differences significantly changes the shape of the resonant mode.

[0123] In the wireless power supply device according to the sixth embodiment of the present invention, by inputting a high-frequency signal with appropriate amplitude and phase to each transmitter, the charging device placed inside the housing becomes easier to charge.

[0124] Furthermore, in the wireless power supply device according to the sixth embodiment of the present invention, it becomes possible to absorb device-related variations such as the arrangement of charging devices placed within the housing. Therefore, by performing variable output control using switches, phase shifters, etc., high power reception efficiency can be achieved.

[0125] [Other Embodiments] The wireless power supply device of the present invention is not limited to the embodiments described above, and various applications and modifications can be made within the scope of the present invention with respect to the configuration of the housing and transmitter, manufacturing conditions, etc.

[0126] For example, in the wireless power supply device of the present invention, multiple housings may be arranged in at least one of the vertical and horizontal directions. In that case, it is preferable that the multiple transmitters are led out from the same wall surface (e.g., the same side) of the housing.

[0127] The wireless power transmission system of the present invention may have other configurations as long as it includes the wireless power supply device of the present invention and a power receiver.

[0128] The wireless power transmission system of the present invention may include, for example, a power supply unit for transmitting microwave power to a transmitter. In that case, the power supply unit is preferably composed of a standard signal generator that outputs a predetermined frequency, an amplifier that amplifies the signal to a predetermined power, and an irreversible element that absorbs reflected signals from the standard signal generator. The transmitter and the power supply unit are preferably connected by a matching circuit. The matching circuit is adjusted to achieve impedance matching with a housing that functions as a resonator at a preset transmission frequency.

[0129] Furthermore, if the reference potential of the matching circuit and power supply unit is approximately the same as the reference potential of the electromagnetic shielding member, a connector such as an SMA (Sub Miniature Type A) terminal may be used for connection.

[0130] In the wireless power transmission system of the present invention, the receiver preferably consists mainly of a receiving antenna, a rectenna composed of a rectifier circuit, a battery, etc. Switches, matching circuits, etc. may be attached as needed. The supplied microwaves resonate in a predetermined mode within the housing and, by efficiently coupling with the rectenna, are converted to DC by the rectifier circuit and charged to the battery. Typical antennas include dipole antennas and loop antennas. Furthermore, an inverted F-type structure in which a portion of the wiring is short-circuited may be adopted for the part that becomes the ground or the reference potential of the receiver. It is also possible to adjust the corresponding frequency by inserting a capacitor or inductor into a portion of the antenna wiring. These should be selected according to the resonant frequency derived from the housing (resonator) formed of electromagnetic wave shielding material.

[0131] Examples of devices with a charging function that have a built-in power receiver include IoT devices such as wireless earphones, smartwatches, electronic pens, rechargeable toys, power tools, dashcams, laptops, remote controls, and drones, as well as electronic devices such as smart meters, wireless speakers, batteries, and sensor modules. A device with a charging function may or may not have a built-in power receiver. For example, a power receiver may be provided on the outside of a device with a charging function.

[0132] 1A, 1B, 1C, 1D, 1E, 1Ea, 1Eb, 1F, 1G, 2A, 2B, 2C, 3A, 3Aa, 3Ab, 3B, 3C, 4A Wireless power supply device 10 Housing 10a Bottom 10b Top 10c Side 20 Transmitter 21 Coaxial probe 22 Waveguide 23 Dielectric substrate antenna 24 Loop antenna 30 Door 35 Cover member 40 Charging device 45 Guide RS Region where magnetic fields reinforce each other RW Region where magnetic fields weaken each other

Claims

1. A wireless power supply device comprising: a housing that encloses the entire internal space with a conductive electromagnetic wave shielding member; and a plurality of power transmitters that supply power to the internal space of the housing, wherein the plurality of power transmitters are arranged so that the positions of their respective tips are spaced apart from each other, and the plurality of power transmitters each form an electromagnetic field distribution with a different center position in the internal space of the housing, and the electromagnetic field distributions are combined to form a composite electromagnetic field distribution in which regions that reinforce electromagnetic fields and regions that weaken electromagnetic fields are adjacent to each other.

2. The wireless power supply device according to claim 1, wherein the plurality of power transmitters are configured to receive high-frequency signals having the same amplitude and phase at each transmitter.

3. The wireless power supply device according to claim 1, wherein the plurality of transmitters are configured to receive high-frequency signals in which at least one of the amplitude and phase differs for some or all of the transmitters.

4. The wireless power supply device according to claim 3, wherein the amplitude and phase of the high-frequency signal differ in some or all of the transmitters, and the amplitude and phase of the other are the same in all of the transmitters.

5. A wireless power supply device comprising: a housing that encloses the entire internal space with a conductive electromagnetic wave shielding member; and a plurality of transmitters that supply power to the internal space of the housing, wherein the plurality of transmitters are arranged so that the positions of their respective tips are spaced apart from each other, and the plurality of transmitters are configured to receive high-frequency signals having the same amplitude and phase.

6. The wireless power supply device according to any one of claims 1 to 5, wherein the tips of the plurality of power transmitters are arranged symmetrically with respect to the center of the housing.

7. The wireless power supply device according to claim 6, wherein, when viewed from above, the tips of the plurality of power transmitters are positioned symmetrically with respect to the center of the housing, and the tips of the plurality of power transmitters are positioned in an intermediate region between the center of the housing and the wall surface of the housing.

8. The wireless power supply device according to any one of claims 1 to 7, wherein the tips of the plurality of power transmitters are located on the same virtual plane.

9. The wireless power supply device according to any one of claims 1 to 8, wherein each of the plurality of power transmitters has the same shape.

10. The wireless power supply device according to any one of claims 1 to 9, wherein the plurality of power transmitters are led out from the same wall surface of the housing.

11. A wireless power transmission system comprising: a wireless power supply device according to any one of claims 1 to 10; and a power receiver disposed in the internal space of the housing of the wireless power supply device.

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