JP6511364B2 - Wireless power supply system - Google Patents

Description

  The present invention relates to a wireless power feeding system suitable for wireless power transmission.

  In recent years, development of wireless power feeding technology has been activated, and various technologies have been proposed (for example, see Patent Document 1). The mobile wireless power transfer system described in Patent Document 1 includes a multiplexing control device that outputs a multiplexing control signal to a power receiving device, and when a plurality of power receiving devices are located along a transmission line, the power receiving device is It is disclosed that it is configured to receive power at time of own power reception time slot in time division multiplex. It is also disclosed that when a plurality of power receiving devices are located along a transmission line, the power receiving device is configured to receive power at a resonance frequency set to itself by frequency multiplexing.

JP 2014-223002 A

  The inventor, for example, installs a transmission line in a vehicle with a length close to the length of the wavelength of AC power (for example, λ / 4) for energizing the transmission line, and AC power is continuously distributed, for example, λ / 4 current distribution. Even if the power receiving device is installed at any position of the transmission line which changes in the above, it is considered to be able to supply desired power to the power receiving device.

  However, when the technology described in Patent Document 1 is used, the power transmission apparatus needs a configuration for time division multiplexing or frequency multiplexing, and the power receiving apparatus needs a configuration for adjusting the power reception timing to the power receiving time slot. Each require a configuration to match the resonant frequency.

  An object of the present invention is to provide a wireless power feeding system in which the amount of power feeding to a power receiving device can be freely changed using a simple configuration.

  In order to achieve the above object, the invention according to claim 1 includes a power transmission device, a transmission line, a power reception device, and a reflection device. The power receiving device is disposed in a first predetermined area of the transmission line, and wirelessly receives AC power from the first predetermined area. On the other hand, the reflection device is disposed in a second predetermined area where a standing wave current larger than the standing wave current in the first predetermined area of the transmission line flows, and when receiving the AC power from the second predetermined area At least a part of the AC power is reflected to the transmission line. At this time, the transmission line raises the standing wave current in the first predetermined area in accordance with the AC power reflected by the reflecting device, and the power receiving device receives the standing wave in the first predetermined area raised by the reflecting device. AC power is received wirelessly according to the current. Thereby, the standing wave current in the first predetermined area, which is lower than the standing wave current in the second predetermined area, can be increased. As a result, the amount of power supplied to the power receiving device can be freely changed using a simple configuration.

Configuration diagram schematically showing a wireless power supply system in the first embodiment (A) is a structural example schematically showing a part of the transmission line and the power receiving antenna of the power receiving device, (b) is a structural view schematically showing the construction of the termination of the transmission line Standing wave current characteristics according to the position of the transmission line Characteristics of standing wave current according to the area of the transmission line when the power receiving device is installed Characteristic diagram of the feed rate according to the area of the transmission line Configuration diagram schematically showing a wireless power supply system in the second embodiment (part 1) Configuration diagram schematically showing a wireless power feeding system (part 2) Characteristic diagram of the feed rate according to the area of the transmission line The block diagram which shows typically the wireless electric power feeding system in 3rd Embodiment Specific configuration example when installing a standing wave ratio adjuster at the end of a transmission line

  Hereinafter, some embodiments of the wireless power supply system will be described with reference to the drawings. About the same composition among each embodiment, the same numerals as the numerals attached to the previous embodiment are attached, explanation is omitted as needed in the later embodiments, and different parts are mainly explained.

First Embodiment
1 to 5 show an explanatory view of the first embodiment. As an example of the overall configuration is shown in FIG. 1, the wireless power feeding system 1 is configured such that the power transmitting device (master) 2 and the power receiving devices (slaves) 31 to 3 n are wirelessly coupled (electric field / magnetic field) through the transmission line 4. Be done. For example, the power receiving device 3n is configured as a second power receiving device.

  For example, a battery (not shown: power supply source) is connected to the power transmission device 2, and power is supplied to the plurality of power reception devices 31, 32 to 3 n through the transmission line 4 according to the power of the battery. , 32 to 3 n operate according to their supplied power. The wireless power supply system 1 is synonymous with a power line power supply system. The wireless power supply system 1 is preferably applied to wireless power transmission of various sensors and actuators particularly for vehicles.

  The power transmission device 2 includes a feed circuit 5 and a matching unit 6. The feeder circuit 5 outputs alternating current power (high frequency power, for example, sine wave voltage / current) of a predetermined frequency (for example, several MHz) to the transmission line 4. The matching unit 6 performs impedance matching between the feeding circuit 5 and the transmission line 4. The feeder circuit 5 is configured by connecting the transmission line 4 via the matching unit 6. A termination 7 is connected to the termination 4 b of the transmission line 4.

  FIG. 2A and FIG. 2B show a configuration example of the transmission line 4. The transmission line 4 is formed of, for example, a twisted pair (twisted pair cable) in which a pair of transmission lines 8 and 9 are twisted at a twisting portion 10. The pair of power transmission lines 8 and 9 have an opening 11 between adjacent twisting portions 10. Among the openings 11 between all adjacent twisting portions 10, the opening 11a between specific twisting portions 10a (hereinafter referred to as a specific opening 11a) is larger than the opening 11 between other twisting portions 10 or between the twisting portions 10 and 10a. It is provided. In the near field around the specific opening 11a, the power receiving devices 31, 32 to 3n of the power receiving antennas 13 are installed. The power receiving antenna 13 is formed of, for example, a loop coil having an opening 14, and interlinks the magnetic flux emitted from the specific opening 11 a of the transmission line 4 with the opening 14 of the power receiving antenna 13. Thus, the power receiving antenna 13 can receive power from the transmission line 4 in accordance with the electromagnetic induction phenomenon (mainly magnetic field).

  As shown in FIG. 2A, the transmission line 4 is disposed by extending a twisted wire pair in a predetermined direction (one direction: for example, the X direction) by a predetermined length (about several meters). In addition, although this predetermined direction may be a certain linear direction, it may be bent or bent. Further, as a specific example is shown in FIG. 2 (b), the pair of transmission lines 8 and 9 of the transmission line 4 are coupled by the coupling portion 12, whereby the pair of twisted pair lines are partially (for example, In the form of a loop connected by Note that FIG. 1 schematically shows that the terminator 7 is configured by a short circuit line (e.g., the coupling portion 12). The transmission line 4 is not limited to the configuration shown in FIGS. 2 (a) and 2 (b).

  As shown in FIG. 1, a plurality of power receiving devices 31 to 3 n are disposed in the vicinity of the transmission line 4, and a plurality of predetermined regions R 1 and R 2 to R n of the predetermined direction (for example, X direction) Are arranged to receive power in the predetermined regions R1 and R2 to Rn. Each of the power receiving devices 31 to 3 n includes the power receiving antenna 13 and the load 15 as shown in FIG. The number of installed power receiving devices 31 may be any number as long as it is two or more.

The operation of the above configuration will be described.
When the feeding circuit 5 outputs AC power to the transmission line 4, a standing wave is generated in the transmission line 4. The value of the standing wave current according to the position of the transmission line 4 is normalized and shown in FIG. 3, and the amplitude of the standing wave current when the current value of the installation position of the terminator 7 is 1 is shown. Here, the frequency of the AC power output from the power transmission device 2 is, for example, 6.78 [MHz], and the line length X [m] of the transmission line 4 is, for example, 10 [m]. The amplitude of the standing wave current at this time largely changes in accordance with the regions R <b> 1 to Rn of the transmission line 4. Assuming that the frequency of the AC power output from the feed circuit 5 to the transmission line 4 is f, the wavelength λ is calculated by the speed of light c / frequency f.

  For example, in the case where the line length X [m] of the transmission line 4 matches the quarter of the wavelength λ (= λ / 4), or the line length X is smaller than the quarter of the wavelength λ Shows the characteristic that the amplitude of the standing wave current continuously increases from the base end 4a to the terminal end 4b of the transmission line 4 close to the power transmission device 2, and each part of the transmission line 4 and the value of the standing wave current are There is a one-to-one relationship. In the present embodiment, in particular, the standing wave current is compared with the case where the termination 4 b of the transmission line 4 is formed by a short circuit and the standing wave regulator 207 is provided as shown in the third embodiment described later. The degree of change (for example, the degree of increase) of

  On the other hand, as shown to this embodiment, the case where the power receiving apparatuses 31-3n are installed in each area | region R1-Rn is considered. When the power receiving devices 31 to 3 n are aligned with the transmission line 4, the kQ product is relatively high and the signals are not reflected in principle. The kQ product is an index indicating the power transfer efficiency of wireless power feeding. However, when the kQ product is low and the degree of misalignment is large, the reflection is also large. The reflection coefficient Γ at this time is expressed as the following equation (1).

Γ = (ZL-Zi) / (ZL + Zi) (1)
Here, ZL indicates the impedance when looking at the base end 4a side of the transmission line 4 from the installation areas R1 to Rn of the power receiving devices 31 to 3n, and Zi indicates the installation areas R1 to R8 of the power receiving devices 31 to 3n from the transmission line 4 The impedance which looked at the terminal 4b side is shown. The reflection coefficient Γ changes according to each of the regions R1 to R8.

  The inventor installs the power receiving devices 31 to 3 n in the respective regions R 1 to R 8 of the transmission line 4, and the power receiving devices 31 to 3 n have the same kQ product with the transmission line 4. The simulation is performed assuming that the At this time, assuming that the distance between the proximal end 4a and the terminal end 4b of the transmission line 4 is 10 m, and eight terminals are arranged at intervals of 1 m from the region R8 of the terminal end 4b toward the power transmission device 2, simulation is performed. Is going. Further, the impedance of the load 15 of each of the power receiving devices 31 to 3 n is 50 [Ω]. The simulation results are shown in FIG.

  Comparison of FIG. 3 and FIG. 4 reveals that the standing wave current rises in the regions R1 to R4, but decreases in the regions R5 to R8. This indicates that the current reflection by the power receiving device installed in the regions R5 to R8 is larger than the current reflection by the power receiving device installed in the regions R1 to R4. Furthermore, the standing wave current gradually increases in degree toward the base end 4 a side of the transmission line 4 and gradually increases in degree toward the end 4 b side of the transmission line 4. found.

  Further, as shown in FIG. 5, the inventor has obtained a simulation result of the ratio of power feeding to each of the power receiving devices 31 to 3 n when the kQ product is changed. The vertical axis indicates the ratio of power feeding, and this ratio indicates the ratio of the amount of power feeding to each of the regions R1 to R7 when the total amount of power fed to all the power receiving devices is one, The ratio is proportional to the square of the standing wave current. It is also known that the rate of feeding also increases gradually toward the proximal end 4 a of the transmission line 4 and gradually increases toward the end 4 b of the transmission line 4.

  Therefore, when the power receiving device R8 (= Rn) disposed on the region R8 side (corresponding to the second predetermined region) receives the AC power, a part of the AC power is reflected to the transmission line 4, and the transmission line 4 becomes the region R1. The standing wave currents of ~ R4 (corresponding to the first predetermined area) are increased, and the power receiving device 31 disposed on the side of these areas R1 wirelessly transmits the AC power corresponding to the increased standing wave current by radio. It is estimated that power is received. As a result, although a normalized current difference of about 0.8 at the maximum is generated between the region R1 and the region R8 in FIG. 3, the power receiving devices 31 to 3n are connected to the transmission line 4 as shown in FIG. By arranging while adjusting the product, it is possible to suppress to a maximum normalized current difference of about 0.25 between the region R1 and the region R4, and confirm that the ratio of power feeding to each of the power receiving devices 31 to 3n can be approximately equalized. did it.

  Since it is considered difficult to install so as to have substantially the same kQ product, installing each of the power reception devices 31 to 3 n so as to have a kQ product of a predetermined range based on a predetermined kQ product desirable. This makes it possible to obtain characteristics close to the simulation results. Thereby, the electric power supplied to each of the power receiving devices 31 to 3 n can be made as uniform as possible.

  According to the present embodiment, the power receiving device 31 and the like are disposed on the region R1 side, and the power receiving device 3n and the like are disposed on the region R8 side where the standing wave current is larger than the region R1. At least a part of the alternating current power can be reflected to the transmission line 4, and the standing wave current on the region R1 side can be increased according to the reflected alternating current power. Thereby, the ratio of power feeding to the power receiving devices 31 to 3 n can be freely changed as much as possible using a simple configuration.

  Further, by adjusting the kQ product or the like, it is possible to equalize the feeding power to the plurality of power receiving devices 31 to 3 n as much as possible. In particular, even if the plurality of power reception devices 31 to 3 n are configured to have the same configuration, and the kQ product is within the predetermined range, the plurality of power reception devices 31 to 3 n are adjusted by adjusting the kQ product to the predetermined range (for example, 210210). Power supplied to the power receiving devices 31 to 3 n can be made as uniform as possible.

Second Embodiment
6 to 8 show additional explanatory views of the second embodiment. FIG. 6 shows the wireless power feeding system 101 in which the reflecting device 103 n is installed on the end 4 b side of the transmission line 4. The reflection device 103 n is configured, for example, by connecting the reception coil 113 and the capacitor 116 in series, and is configured to have a predetermined resonance frequency. Even when the load 15 is not connected and the power is received from the transmission line 4, the reflection device 103 n theoretically consumes no power, and totally reflects the input AC power in principle. Note that the internal resistance consumption of the reflection device 103 n is excluded. Even if the reflecting device 103 n is installed in the near field of the transmission line 4, kQ ≒ 0 substantially.

  Further, FIG. 7 shows a wireless power feeding system 101a in which the terminating device 103na is installed on the end 4b side of the transmission line 4. The termination device 103na has a configuration similar to that of the power reception device 31 or the like, but assumes that the coupling coefficient k with the transmission line 4 is set higher than that of the other power reception devices 31 or the like. It is around 2100.

  FIG. 8 shows simulation results of the wireless power supply system 1 described in the first embodiment and the wireless power supply systems 101 and 101a in the present embodiment. In FIG. 8, simulation results when the power receiving devices 31 to 3 n are disposed in all the regions R1 to R8 are indicated by diamond marks, and simulation results when the reflection device 103 n is disposed in the region R8 are indicated by triangle marks. ing. Further, FIG. 8 also shows a simulation result in which the termination device 103na is mounted in the termination region R8 so as to have a kQ product (= 2100) higher than the other regions R1 to R7 using square marks. The vertical axis indicates the ratio of power feeding, but this ratio indicates the ratio of the amount of power feeding to each of the regions R1 to R8 when the total amount of power fed to all the power receiving devices 31 to 3 n is 1. The ratio is proportional to the square of the standing wave current.

  When the power receiving devices 31 to 3 n-1 are installed in the regions R1 to R7 and the reflecting device 103 n is installed in the region R8, feeding is performed on the base end 4a side of the transmission line 4 as shown by triangle marks in FIG. The ratio of power feeding becomes smaller at the end 4 b side of the transmission line 4. Therefore, it can be understood that the distribution of the standing wave current of the transmission line 4 can be largely changed by installing the reflecting device 103 n in the region R8.

  Conversely, when the termination device 103na is installed to increase the kQ product, the amount of power supplied to the termination device 103na is the amount of power supplied to the other power reception devices 31 to 3n-1, as indicated by a square mark in FIG. It will be higher than. When the terminating device 103na is installed, it can be understood that the distribution of the standing wave current can be made uniform as compared with the case where the reflecting device 103n is installed.

  Further, as shown by a diamond mark in FIG. 8, in the case where the termination device 103na is installed by installing the power reception devices 31 to 3n in the regions R1 to R8 so as to have the same predetermined kQ product (= 210). In comparison, the distribution of the standing wave current can be made more uniform, and it can be understood that the feeding ratio can be made more constant.

Also by the configuration of the present embodiment, the same effects as those of the above-described embodiment can be obtained.
Third Embodiment
9 and 10 show additional explanatory views of the third embodiment. The third embodiment shows a mode in which a standing wave ratio adjuster 207 is installed at the end. The wireless power supply system 201 illustrated in FIG. 9 includes a power transmission device 2, power reception devices 31 to 3 n, a transmission line 4, and a standing wave ratio adjuster 207. A specific configuration example of the standing wave ratio adjuster 207 is shown in FIG. As shown in FIG. 10, in the case where the transmission line 4 is formed by, for example, a twisted pair in which the transmission lines 8 and 9 are twisted at the twisting portion 10, the standing wave ratio adjuster 207 includes the resistor 212. The resistor 212 is configured to couple the ends of the transmission lines 8, 9. The standing wave ratio adjuster 207 is set to an impedance value smaller than the characteristic impedance of the transmission line 4.

  For example, by inserting the standing wave ratio adjuster 207 at the end of the transmission line 4, for example, the distribution of the standing wave current can be smoothed. In the present embodiment, since the standing wave ratio adjuster 207 is connected, the degree of increase of the standing wave current can be made particularly small as compared with, for example, the transmission line 4 of the first embodiment. As a result, the amount of power supplied to the power reception devices 31 to 3 n can be freely changed.

(Other embodiments)
The present invention is not limited to the above-described embodiment. For example, the following modifications or expansions are possible. The configurations of the embodiments described above can be combined as appropriate and applied as appropriate.

  For example, it is desirable to apply the system 1, 101, 101a using the transmission line 4 whose line length X [m] is λ / 4 or less, but using the transmission line 4 whose line length X [m] exceeds λ / 4 It is good. In the first embodiment, a mode in which the power receiving device 3n is applied as the "reflecting device" is shown, but the power receiving device 3n-1 may be regarded as a reflecting device, for example. It is not limited to the installed power receiving device.

The transmission line 4 has been described by taking the configuration in which the pair of power transmission lines 8 and 9 are twisted together as an example, but it is not limited to this.
In the first embodiment, although the plurality of power receiving devices 31 to 3 n are all provided with the power receiving antenna 13 and the load 15 and have the same configuration as each other, the present invention is not limited thereto. The same configuration may be used, and all of the configurations may be different.

  The power reception device 3n, the reflection device 103n, and the termination device 103na can increase the reflection effect of current by being installed in the region R8 where the standing wave current is an antinode.

  In the drawing, 2 is a power transmission device, 4 is a transmission line, 31 to 3 n are power reception devices (for example, 3 n is a second power reception device and a reflection device), R1 to Rn are regions (for example, R1 and R2 are first predetermined regions, Rn Denotes a second predetermined area), 103 n denotes a reflection device, and 103 na denotes a termination device (reflection device).

Claims (6)

A power transmission device (2) for transmitting AC power;
A transmission line (4) for transmitting AC power transmitted from the power transmission device;
Power receiving devices (31, 32,...) Arranged in a first predetermined area of the transmission line and receiving AC power from the first predetermined area by radio;
It is arranged in a second predetermined area (Rn) through which a standing wave current larger than the standing wave current in the first predetermined area (R1, R2,...) Of the transmission line flows, and receives AC power from the second predetermined area Then, a reflector (... 3n, 103n, 103na) for reflecting at least a part of the received AC power to the transmission line is provided,
The transmission line raises the standing wave current of the first predetermined area according to the AC power reflected by the reflecting device, and the power receiving device is the standing wave of the first predetermined area raised by the reflecting device. A wireless power supply system that receives AC power wirelessly according to current. In the wireless power supply system according to claim 1,
The wireless power supply system, wherein the reflection device (3n) is configured by a second power reception device (3n) configured to have the same configuration as at least one of the plurality of power reception devices. In the wireless power supply system according to claim 1,
The wireless power supply system, wherein the reflection device (103na) includes a termination device (103na) installed to increase a kQ product as compared to a kQ product between the power reception device and the transmission line. In the wireless power supply system according to claim 2,
The wireless power supply system, wherein the power receiving device and the second power receiving device (31 to 3n) are all installed so as to have a kQ product of a predetermined range with the transmission line. In the wireless power supply system according to claim 1 or 4,
The wireless power supply system further comprising a standing wave ratio adjuster (207) for adjusting the standing wave ratio of the transmission line at the end of the transmission line. The wireless power supply system according to any one of claims 1 to 5.
The wireless power feeding system in which the reflection devices (3n, 103n, 103na) are installed in a region (R8) where a standing wave current is an antinode.

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