KR102327580B1 - Wireless power transmit apparatus - Google Patents

Abstract

The wireless power transmitter according to this embodiment includes an oscillator that forms a signal of an upper industrial scientific medical (ISM) band, a power divider that distributes power of the signal, and shifts the phase of the distributed signal, A sub-array antenna including an RF signal processing unit for amplifying the power of a signal, a power distributor for distributing the power amplified signal, and a plurality of unit antennas for receiving and radiating the power amplified signal from the power divider includes an arrayed antenna.

Description

WIRELESS POWER TRANSMIT APPARATUS

The present technology relates to a wireless power transmission device.

The wireless power transmission method is largely divided into an inductive coupling method, a non-radiative method including a magnetic resonance method, and a radiation method for transmitting power and receiving the RF signal. The non-radiation method is a wireless power transmission method that has been recently used for charging mobile phones, and it can be charged within a few cm.

The non-radiative wireless power transmission method is a technology that can be mainly used indoors because it is mainly used when the transmitting side and the receiving side are in contact or in a short distance within 1 to 2 meters. On the other hand, the radiation method using electromagnetic waves has the advantage that it can be applied at a distance of several to several tens of meters or more and in various indoor/outdoor environments.

This wireless power transmission technology is a trend that is becoming increasingly important in recent years because it can improve the problems associated with the installation and maintenance of various smart devices operated by wire or using a battery.

In the radiation-type wireless power transmission method, one RF unit (radio frequency unit) that forms and provides a power signal for each unit antenna is coupled one by one. There is a difficulty in that the cost increases when implementing the transmitter because expensive RF parts are required as much as the number of . Furthermore, loss due to dielectric loss (loss tangent), etc. occurring in the antenna occurs, resulting in a problem of power loss.

One of the problems to be solved by the present technology is to solve the above-described difficulties of the prior art. The present technology has a low loss compared to the prior art and is one of the problems to be solved to form an economical wireless power transmission transmitter.

The wireless power transmitter according to this embodiment includes an oscillator that forms a signal of an upper industrial scientific medcal (ISM) band, a power divider that distributes the power of the signal, and shifts the phase of the distributed signal. A sub-array antenna including an RF signal processing unit for amplifying the power of a signal, a power distributor for distributing the power amplified signal, and a plurality of unit antennas receiving and radiating the power amplified signal from the power divider It includes an arrayed array antenna.

According to this embodiment, it is possible to obtain high power transmission efficiency by transmitting power using a signal of the upper ISM band frequency band, and there is an advantage that a wireless power transmission device can be economically formed therefrom.

1 is a block diagram showing an outline of a wireless power transmitter according to the present embodiment.
2 is a block diagram showing an outline of an RF signal processing unit according to the present embodiment.
3 is a diagram schematically illustrating an embodiment of a power distributor.
4 is a diagram schematically illustrating a coupling relationship between a power divider and unit antennas included in a sub-array antenna according to the present embodiment.
FIG. 5(a) is a plan view of an embodiment in which a power distributor and a sub-array antenna are integrally formed, and FIG. 5(b) is a diagram schematically illustrating a cross-section taken along line A-A' of FIG. 5(a).
6 is a schematic diagram illustrating examples of arrangement of a wireless power transmitter according to the present embodiment.
7(a) to 7(d) are diagrams comparing air efficiency during wireless power transmission using signals of a conventional ISM band and an upper ISM band.
8 is a diagram comparing air efficiency when one RF signal processor is connected to one unit antenna as in the prior art and air efficiency when one RF signal processor is connected to one sub-array antenna.

A wireless power transmitter according to the present embodiment will be described with reference to the accompanying drawings. 1 is a block diagram showing an outline of a wireless power transmitter 10 according to the present embodiment. Referring to FIG. 1 , the wireless power transmitter 10 according to the present embodiment includes an oscillator 100 that forms a signal of an upper industrial scientific medcal (ISM) band, and a power divider that distributes power of the oscillated signal. A divider 200, an RF signal processing unit (RF signal processing unit, 300a, 300b, ..., 300n) that shifts the phase of the divided signal and amplifies the power of the shifted signal, and the power of the amplified signal A plurality of unit antennas (500a ₁ , . .., 500n _k ) including sub-array antennas (500a ₁ , ..., 500n _k ) include an array antenna in which they are arranged.

The oscillator 100 forms and outputs a signal of an upper industrial scientific medical (ISM) band. The frequency of the typical ISM band is 13.553~13.567 MHz, 26.975~27.283 MHz, 40.66~40.70 MHz, 2.4~2.48 GHz, and 5.725~5.875 GHz bands. It may further include a frequency.

The frequency of the upper ISM band according to the present embodiment may be a frequency of 24 to 24.25 GHz, 61 to 61.5 GHz, 122 to 123 GHz, or 244 to 246 GHz, which is a frequency higher than that of the above-described ISM band.

Equation 1 below is a Friis transmission equation representing power received by the unit antenna on the wireless power receiving side.

(Pr: receive power, Pt: transmit power, Nt: the number of single antennas in the transmit array antenna, λ: wavelength, c/f (c: luminous flux, f: frequency), k(wavenumber): wave number, 2π/λ, r _n : Distance between the nth transmitter unit antenna and the receiver, β _n : Phase of the nth transmitter unit antenna, Gt(θn, φn): Antenna gain for the nth transmitter unit antenna, Gr(θn, φn): Receiving unit Antenna gain for the antenna, θn: polar angle between the nth transmitter unit antenna and the receiving antenna, φn: azimuthal angle between the nth transmitter unit antenna and the receiving antenna)

As shown in Equation 1, as the frequency of the signal to be transmitted for power transmission increases (the wavelength of the transmitted signal decreases), the power received by the unit antenna of the receiving side decreases. For this reason, in the prior art, the frequency of a signal for transmitting power is limited to a low frequency band of the ISM band.

However, as the frequency increases, the area of a unit antenna for transmitting a signal may be reduced. For example, assuming a quadrangular unit antenna, the length of each side of the quadrangle is inversely proportional to the frequency to be transmitted, so that the area of the unit antenna is inversely proportional to the square of the frequency when a high frequency transmission signal is used.

If the area formed by the array antennas formed by arranging the unit antennas is the same, the area of the unit antenna decreases as the frequency increases, so that more unit transmit antennas and receive antennas can be arranged in the same area.

Referring to Equation 1, since the number of unit antennas of the transmission array antenna is included in the absolute value, the square of Nt is eventually generated by calculating the equation in the absolute value and then calculating the square. This is multiplied by Nt of the leftmost denominator of the equation, and as a result, the received power Pr is proportional to the number of transmit unit antennas (Nt).

That is, by transmitting power with a signal having an upper ISM band frequency, the number of unit antennas for transmitting a transmission signal can be increased to increase the total power transmitted by the transmitting side, and higher power despite a decrease in efficiency in the medium can receive Furthermore, it is possible to increase the number of unit antennas on the receiving side, thereby obtaining higher reception power.

The power divider 200 divides and outputs the power of the signal provided by the oscillator.

2 is a block diagram showing an outline of the RF signal processing units 300a, 300b, ..., 300n according to the present embodiment. 2, each RF signal processing unit (300a, 300b, ..., 300n) is a phase shifter (phase shifter, 310) for shifting the phase of the signal provided by the power divider 200 (phase shifter, 310), and a power amplifier 320 amplifying the power of the shifted signal, and the phase shifter 310 and the power amplifier 320 are connected in a cascade.

The phase shifter 310 shifts the phase of the signal provided by the power divider 200 so that the beam formed by the sub-array antennas 500a ₁ , ..., 500n _{k is formed toward the receiving side.} Steer the beam. In one embodiment, the phase shifter 310 controls the phase of the signal provided to each sub-array antenna (500a, 500b, ..., 500n), respectively, each sub-array antenna (500a, 500b, ..., 500n) to steer the forming beam. The power amplifier 320 amplifies the power of the signal provided by the phase shifter 310 to the unit antennas 500a ₁ , ..., included in each sub-array antenna 500a, ..., 500n. 500n _k ).

Conventionally, one unit antenna is connected to one RF signal processing unit. For example, in the case of a wireless power transmitter including 100*100 unit antennas, 10000 RF signal processing units are coupled to each unit antenna. However, since the phase shifter and the power amplifier included in the RF signal processing unit are expensive, the prior art wireless power transmitter has low economic feasibility. Furthermore, when a plurality of unit antennas are used to transmit higher power, economic efficiency is further lowered.

However, in the power transmitter 10 according to the present embodiment, one RF signal processing unit 300a, 300b, ..., 300n is provided for each sub-array antenna 500a, ..., 500n including a plurality of unit antennas. are coupled In the case of a wireless power transmitter including 100*100 unit antennas as in the example described above, when one sub-array antenna includes 10*10 unit antennas, 100 sub-array antennas are formed, and for each of these, 100 sub-array antennas are formed. When the RF signal processing unit is connected, 100 RF signal processing units are required. In this case, the number of RF signal processing units required in the prior art can be reduced to 1/100, and a high cost reduction effect can be obtained therefrom.

The power dividers 400a, 400b, ...400n divide the power of the signal output by the RF signal processing units 300a, 300b, ...300n to each of the unit antennas 500a ₁ , ..., 500n _k ) is provided in Figure 3 is a diagram schematically showing an embodiment of the power divider (400a, 400b, ... 400n). Referring to Fig. 3, the power dividers 400a, 400b, ... 400n are waveguide power dividers. The waveguide power divider includes a metal cavity 410 formed of a metal material having high conductivity, an input slot 420 formed on one side of the metal cavity 410, and an output slot to which signals having distributed power are output, respectively. (output slots, 430).

The signal output from the RF signal processing unit is provided to the input slot 420 , is totally reflected and resonated inside the metal cavity 410 , so that power is distributed and output to each output slot 430 . The inside of the metal cavity 410 may be filled with air, from which the power loss of the power divider is close to zero.

A power distributor according to the prior art has a form in which a conductive strip is formed on a dielectric substrate based on a transmission line. In the power divider based on the transmission line, the power of the input signal propagates along the conductive strip, and loss due to the dielectric occurs in the process of power distribution. However, the power divider according to the present embodiment provides an advantage that power loss can be greatly reduced because the input signal is totally reflected and resonated inside the metal cavity filled with air to distribute power.

3 is illustrated as having 5*5 output slots in a metal cavity 410 having a hexahedral shape. However, this is purely for illustration, and it is sufficient if the shape of the metal cavity is a volume formed on one side and the other side, such as a cylinder, a polyhedral column, etc., and may have a smaller number of slots, and may have a large number of slots. Furthermore, the number of slots formed horizontally and the number of slots formed vertically may be different from each other.

4 is a diagram schematically illustrating a coupling relationship between _{the power distributor 400 and the unit antennas 500a 1} , 500a ₂ , ... included in the sub-array antenna according to the present embodiment. Referring to FIG. 4 , the power distributor 400 and each of the unit antennas 500a ₁ , 500a ₂ , ... may be interconnected with connectors 610 and 615 . As an example, each of the unit antennas 500a ₁ , 500a ₂ , ... may be a Yagi antenna, a patch antenna, or a PCB-based antenna, which are respectively an antenna-side connector 615 and a power distributor 400-side connector ( 610) may be coupled to each other. Although the illustrated embodiment shows a configuration in which the connector 610 is disposed on the antenna side connector 615 and the power distributor 400 side, respectively, it is also possible to connect the unit antenna and the power distributor with a single connector.

5 is a diagram illustrating another embodiment of the power divider 400 and the sub-array antenna 500 . 5 (a) is a plan view of an embodiment in which the power distributor 400 and the sub-array antenna 500 are integrally formed, and FIG. 5 (b) is a schematic cross-section taken along line A-A' of FIG. it is one drawing 5 (a) and 5 (b), the signal provided through the input slot (see FIGS. 43 and 420) is guided through the wave guide (WV), impedance matching through the connection aperture (440) A cavity 410 is provided. The signal is resonated and reflected in the cavity 410 to distribute power, and the distributed signal is provided to the plurality of unit antennas 500a ₁ , 500a ₂ , 500a ₃ , and 500a ₄ to be radiated to the outside. The power distributor 400 and the sub-array antenna 500 illustrated in FIG. 5 may be formed by stacking three metal layers.

In one embodiment, the power transmission device 10 according to the present embodiment may be mounted on a mechanical steering device. The RF signal processing units 300a, 300b, ... 300n (see FIG. 1) shift the phase so as to steer the beam toward the receiving side, but the mechanical steering device of the antennas to direct the power transmission device 10 at an angle of a larger range. The direction of orientation can be controlled mechanically.

6 is a schematic diagram illustrating examples of the arrangement of the wireless power transmitter 10 according to the present embodiment. Referring to FIG. 6A , the wireless power transmitter 10 may be disposed on the ceiling of an indoor space. The wireless power transmitter 10 disposed on the ceiling may wirelessly transmit power to the devices 20 positioned in an indoor space. In addition, the wireless power transmission device 10 may be embedded in or mounted in home appliances such as an air conditioner, lighting, a beam projector and a beam projector screen located in an indoor space. In one embodiment, the devices 20 may be IoT devices including the power receiving device 20 .

Referring to FIG. 6B , a radio wave absorber 15 may be further disposed in an indoor space in which the wireless power transmitter 10 is disposed. The beam provided by the wireless power transmitter 10 may be scattered indoors or spread widely to affect a living body located in an indoor space. Therefore, it is possible to prevent the beam from being scattered and reflected and provided to the living body by disposing an absorber that absorbs radio waves.

Experiment result

Hereinafter, experimental results for the wireless power transmitter according to the present embodiment will be described with reference to FIGS. 7 to 8 .

In the experimental results below, the air efficiency is defined as the ratio between the total power of the transmit array antenna input unit and the total power of the receive array antenna output unit. The total power of the transmit array antenna input unit may be calculated as the sum of output powers of all transmit RF terminals, and the total power of the receive array antenna output unit is calculated as the sum of all receive sub-array antenna output powers.

In this experiment, the wireless power receiver consists of n x n single antennas, a rectifier for rectifying the received signal, and an RF combiner for merging the power of the received signal.

The experiment was made through Matlab simulation based on the Fries equation specified in Equation 1 above.

In the experiment illustrated in FIGS. 7(a) to 7(d), with respect to the conventional wireless power transmitter to which one RF signal processing unit is connected to each single antenna, the existing ISM band of 5.8 GHz and the upper ISM band of 24 GHz evaluated the air efficiency during wireless power transmission transmission. In evaluation, the distance between the transmitter/receiver is 10 meters, the output power (Pt) of the transmitter is 10 W, the resolution of the phase shifter is 4 bit, the interval between the unit antennas is 0.7 λ, and the gain of the unit antenna of the transmission/modification is 8/8 dBi. It was set, and Fig. 7 (a) and 7 (b) is the area of the transmitting antenna 1 * 1m ^2, the area of the receiving antenna with 0.2 * 0.2m ^2, Fig. 7 (c) and 7 (d) is transmitted The area of the antenna is set to 2*2m ² , and the area of the receiving antenna is set to ^{0.1*0.1m 2 .}

7(a) and 7(c) are diagrams illustrating air efficiency during wireless power transmission in the existing ISM band, 5.8GHz, and FIGS. 7(b) and 7(d) are wireless in the upper ISM band, 24GHz It is a diagram comparing air efficiency during power transmission.

7(a) and 7(b), in the wireless power transmitter according to the prior art, the air efficiency during wireless power transmission in the existing ISM band of 5.8 GHz was 16.9%, but in the present upper ISM band, 24 GHz, the The air efficiency during power transmission was increased by about 4 times to 83%, and referring to FIGS. 7(c) and 7(d), the air efficiency during wireless power transmission in the existing ISM band of 5.8GHz was 16.6%, but , it can be seen that the air efficiency during wireless power transmission in the upper ISM band, 24 GHz, was 82.1%, which was about a 4-fold increase in efficiency.

In the experiment illustrated in FIGS. 7(a) and 7(b), 28*28 unit transmit antennas and 6*6 unit receive antennas could be arranged in the existing ISM band, but in the upper ISM band, the same transmit antennas were used. It is understood that the reason is that 114*114 unit transmit antennas and 23*23 unit receive antennas can be arranged in the area and the area of the receive antenna, so that the transmit power and the receive power are increased.

Furthermore, in the experiments illustrated in FIGS. 7(c) and 7(d), 56*56 unit transmit antennas and 3*3 unit receive antennas could be arranged in the existing ISM band, but the same transmission in the upper ISM band In the antenna area and the receiving antenna area, 228*228 unit transmit antennas and 11*11 unit receive antennas could be arranged.

Therefore, it is possible to reduce the area of a unit transmit antenna and a unit receive antenna by wirelessly transmitting power using a frequency band higher than that of the existing ISM band, and the number of unit transmit antennas and the unit receive antenna that can be disposed within the same area therefrom. It is understood that as the number of devices increases, greater power can be transmitted and greater power can be received as a major factor in increasing efficiency.

FIG. 8 shows the air efficiency of a transmitter structure in which one RF signal processing unit is connected to one unit antenna as in the prior art and a transmitter structure in which one RF signal processing unit is connected to one sub-array antenna of the present embodiment (10). It is a diagram comparing air efficiency. Experimental conditions are the same as the experimental conditions of FIGS. 7(a) to 7(d), but both the present embodiment and the prior art transmit power using a signal of 24 GHz.

Referring to FIG. 8 , when one RF signal processor is connected to one unit antenna in the prior art, air efficiency was measured to be 83%. In this embodiment, when the sub-array antenna composed of 4*4 unit transmitting antennas and one RF signal processing unit are connected, the air efficiency was measured to be 80%, and the sub-array antenna composed of 8*8 unit transmitting antennas and one In the case of coupling the RF signal processing unit of , the air efficiency was measured to be 73%. That is, when the sub-array antenna including 8*8 unit antennas and one RF signal processor are coupled, it is understood that the air efficiency is reduced by 12%.

However, the prior art requires 112*112 = 12544 expensive RF signal processing units, but according to the present embodiment, 896 RF signal processing units are required, which is only 1/64 of that of the prior art. That is, it can be seen that the number of expensive RF signal processing units can be reduced to 1/64, and thus it is highly economical compared to the prior art.

Since the wireless power transmitter according to this embodiment transmits power as a signal of an upper ISM band, it has high power transmission efficiency compared to the prior art, and it is possible to reduce the number of expensive RF signal processing units, thereby providing economical advantages.

Although it has been described with reference to the embodiment shown in the drawings in order to help the understanding of the present invention, this is an embodiment for implementation, it is merely an example, and those of ordinary skill in the art have various modifications and equivalents therefrom. It will be appreciated that other embodiments are possible. Accordingly, the true technical protection scope of the present invention should be defined by the appended claims.

10: wireless power transmitter 15: absorber
20: device 100: oscillator
200: power divider 300a, 300b, 300n: RF signal processing unit
310: phase shifter 320: power amplifier
400a, 400b, 400n: power divider 410: metal cavity
420: input slot 430: output slot
440: connection aperture WV: wave guide
500a ₁ , ..., 500n _k : unit antenna
500a, 500b, 500n: sub-array antenna
610, 615: connector

Claims (12)

an oscillator forming a signal of an upper ISM (industrial scientific medical) band;
a first power divider that divides the power of the signal;
an RF signal processing unit for shifting the phase of the distributed signal and amplifying power of the shifted signal;
a second power divider for distributing the power amplified signal; and
and an array antenna in which a sub-array antenna including a plurality of unit antennas receiving and radiating a power amplified signal from the second power divider is arranged,
The second power divider,
As a waveguide power divider,
metal cavity,
an input slot formed on one side of the metal cavity;
and a plurality of output slots formed on the other side of the metal cavity to which a unit antenna is connected, respectively;
The single RF signal processing unit is a wireless power transmitter for driving the plurality of unit antennas. According to claim 1,
The upper ISM (industrial scientific medical) band is a wireless power transmitter in any one of the frequency bands of 24 GHz to 24.25 GHz, 61 GHz to 61.5 GHz, 122 GHz to 123 GHz, and 244 to 246 GHz. delete delete According to claim 1,
The wireless power transmitter,
Further comprising connectors to which the output slots and the unit antennas are connected,
The unit antenna may be any one of a patch antenna, a Yagi antenna, and a printed circuit board (PCB) based antenna. According to claim 1,
The second power divider and the plurality of unit antennas are wireless power transmitters that are integrally formed with a waveguide array antenna. 7. The method of claim 6,
The waveguide array antenna comprises:
metal cavity,
a power feeding waveguide formed on one side of the metal cavity;
It includes a plurality of unit antennas formed on the other side of the metal cavity,
The plurality of unit antennas is a wireless power transmitter in the form of a radiation slot. According to claim 1,
The RF signal processing unit,
a phase shifter for shifting the phase of the distributed signal;
and a power amplifier amplifying power of the shifted signal, wherein the phase shifter and the power amplifier are connected in a cascade. According to claim 1,
One of the RF signal processing units is a wireless power transmitter connected to one of the sub-array antennas. According to claim 1,
The wireless power transmitter,
The wireless power transmitter further comprising a rotator mounted on the array antenna to mechanically steer the beam angle of the array antenna. According to claim 1,
The wireless power transmitter,
A wireless power transmitter placed on the ceiling of a room. According to claim 1,
The wireless power transmitter,
Wireless power transmitter mounted on home appliances.

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