JP2002010534A - Receiving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiving device capable of being mounted easily on a cylindrical device and minimizing fluctuations is output power even if the angle of incidence of microwaves fluctuate. SOLUTION: M pieces of rectenna elements 4 are arranged in the cylindrical direction with a prescribed pitch so as to be evenly spaced on the cylindrical side face of a cylindrical conductor 3 of a cylindrical rectenna 1. N pieces of the rectenna elements including the rectenna element with maximum DC power among the M pieces of the rectenna elements 4 are connected in parallel to generate an output power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power receiving device provided with a plurality of rectenna elements for receiving microwaves and converting them into DC power.

[0002]

2. Description of the Related Art Microwave power transmission has attracted attention in fields such as high-altitude wireless relay systems, energy transmission in outer space represented by solar power generation satellites, and robot applications.
Various research and developments are underway. As a power receiving device used for the microwave power transmission, a power receiving device having a planar shape in which a plurality of rectenna elements are arranged on a plane is used in order to improve the efficiency of power transmission and reception in the front direction of the antenna.

[0003]

However, all of the above-described conventional power receiving devices have a planar shape, and have a conformal shape that can be attached along a surface of a desired power receiving device. Has not been developed. For example, in the case of microwave power transmission to a cylindrical space articulated robot or the like, a planar power receiving device cannot be applied as it is.

In the case of a planar power receiving device, the power transmission and reception efficiency is maximized in the front direction of the antenna. Therefore, when the microwave incident angle is changed, the power transmission and reception efficiency is reduced. Output power.

An object of the present invention is to provide a power receiving device that can be easily attached to a cylindrical device and that can minimize fluctuations in output power even when the angle of incidence of microwaves fluctuates. It is.

[0006]

Means for Solving the Problems and Effects of the Invention (1)
First invention A power receiving device according to a first invention is one in which a plurality of rectenna elements that receive microwaves and convert the microwaves into DC power are arranged on a cylindrical side surface of a cylindrical support having a substantially cylindrical shape.

In the power receiving device according to the first aspect of the present invention, since a plurality of rectenna elements for receiving microwaves and converting them into DC power are arranged on the cylindrical side surface of the cylindrical support having a substantially cylindrical shape, It can be easily attached to a device having a shape, and fluctuations in output power can be minimized even when the angle of incidence of microwaves fluctuates.

(2) Second invention A power receiving device according to a second invention is the power receiving device according to the first invention, wherein the plurality of rectenna elements are formed on the cylindrical side surface of the cylindrical support at a predetermined pitch. They are arranged at equal intervals in the radial direction.

In this case, since a plurality of rectenna elements are arranged at regular intervals on the cylindrical side surface of the cylindrical support at a predetermined pitch in the radial direction of the cylinder, DC power is applied to microwaves incident at an arbitrary incident angle. There is always at least one rectenna element having the maximum value, and the fluctuation of the output power can be minimized even when the incident angle of the microwave fluctuates.

(3) Third invention A power receiving device according to a third invention is the power receiving device according to the first or second invention, wherein the rectenna element having the maximum DC power among the plurality of rectenna elements is provided. It further comprises a parallel connection means for connecting in parallel with some other rectenna elements and outputting DC power.

In this case, since the rectenna element having the largest DC power among the plurality of rectenna elements is connected in parallel with some other rectenna elements to output the DC power, the rectenna hardly generates DC power. Excluding the elements, only the rectenna elements having a large direct current can be connected in parallel to increase the output power.

(4) Fourth invention In a power receiving device according to a fourth invention, in the configuration of the power receiving device according to the third invention, the parallel connection means includes a rectenna having a maximum DC power among a plurality of rectenna elements. The element is connected in parallel with another rectenna element adjacent to the rectenna element to output DC power.

In this case, the other rectenna element adjacent to the rectenna element having the largest DC power among the plurality of rectenna elements outputs the next largest DC power after the rectenna element having the largest DC power. Rectenna elements can be connected in parallel to generate higher output power.

(5) Fifth invention In a power receiving device according to a fifth invention, in the configuration of the power receiving device according to the fourth invention, the parallel connection means is a rectenna element connected in parallel among a plurality of rectenna elements. When N is an odd number, when N is an odd number, N rectenna elements arranged on both sides of the rectenna element having the maximum DC power are connected in parallel, and when N is an even number, the DC power is Are arranged on both sides around the rectenna element where
1) N rectenna elements are connected in parallel except for the rectenna element on the end side where the DC power is small among the rectenna elements.

In this case, when N is an odd number, N arranged on both sides around the rectenna element at which the DC power is maximized.
When the rectenna elements are connected in parallel, and N is an even number, of the (N + 1) rectenna elements arranged on both sides around the rectenna element having the largest DC power, the end side having the smaller DC power N rectenna elements except for the rectenna element are connected in parallel, so even if the number of rectenna elements connected in parallel is an odd number or an even number, N rectenna elements are connected in parallel starting from the one with the largest DC power. , And a large output power can always be generated.

(6) Sixth invention A power receiving device according to a sixth invention is the power receiving device according to any one of the third to fifth inventions, wherein the parallel connection means comprises:
When the number of the plurality of rectenna elements is M, [0.2
Two or more rectenna elements are connected in parallel in the range of M] or more and [0.4M + 1] or less (where [x] is a Gaussian symbol and represents the largest positive number not exceeding x). It outputs DC power.

In this case, for M rectenna elements, 2 in the range of [0.2M] or more and [0.4M + 1] or less.
Since more than two rectenna elements are connected in parallel, the output power can always be maximized regardless of the number of all rectenna elements.

(7) Seventh invention A power receiving device according to a seventh invention is the power receiving device according to any one of the third to sixth inventions, wherein the parallel connection means comprises:
A plurality of switch means for connecting a plurality of rectenna elements in parallel, a detection means for detecting the DC power of each of the plurality of rectenna elements, and a rectenna element having a maximum DC power according to the detection result of the detection means; And control means for controlling the connection operation of the plurality of switches so that some of the other rectenna elements are connected in parallel.

In this case, DC power of each rectenna element is detected, and a plurality of switches are connected so that the rectenna element having the maximum DC power and some other rectenna elements are connected in parallel according to the detection result. The connection operation is controlled. Therefore, the DC power can be output by connecting the rectenna element having the maximum DC power of the plurality of rectenna elements and the desired rectenna element in parallel.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a power receiving device according to an embodiment of the present invention will be described with reference to the drawings. FIG.
1 is a block diagram illustrating a configuration of a power receiving device according to an embodiment of the present invention.

The power receiving apparatus shown in FIG. 1 includes a cylindrical rectenna 1, an output power detection and switch control circuit 2, output wires O1 to OM, switches S1 to SM, and load resistors R1 to R1.
RM is provided.

The cylindrical rectenna 1 is provided with M rectenna elements 4 arranged at equal intervals in a cylindrical direction at a predetermined pitch on a cylindrical side surface of a cylindrical conductor 3 serving as a cylindrical support. Each rectenna element 4 receives a microwave transmitted wirelessly through a space and outputs DC power. In the present embodiment, for example, in order to reduce the size of the power transmission / reception system so as to be suitable for space application and robot application of microwave power transmission, the frequency is higher than the S band (2.45 GHz) conventionally used mainly. Operating in the high C band (5.8 GHz) to increase the frequency.

Each rectenna element 4 is connected to a corresponding one of M output wires O1 to OM for transmitting DC power. Each of the output wires O1 to OM is connected to a corresponding one of M load resistors R1 to RM including resistors, the other ends of the respective load resistors R1 to RM are grounded, and the respective load resistors R1 to RM are connected. Consumes DC power output from each rectenna element 4. Each load resistance R1 to RM
Is set to a predetermined value of, for example, 100 to 300Ω, for example, 200Ω.

A plurality of switches S1 to SM are connected between the output wires O1 to OM.
The switch S1 is connected between the output wire 1 and the output wire O2, the switch S2 is connected between the output wire O2 and the output wire O3, and thereafter the switch is connected between the output wires. The output power detection and switch control circuit 2 controls each rectenna element 4 output via each output wire O1 to OM.
Of the M rectenna elements 4 by detecting on / off states of the switches S1 to SM in accordance with the detection results and turning on / off the switches S1 to SM according to the detection result. N rectenna elements 4 are connected in parallel.

The number of rectenna elements 4 is not particularly limited, but is preferably five or more. In the present embodiment, for example, nine rectenna elements are used. In addition, the arrangement interval of the rectenna elements 4 is preferably a constant pitch. In the present embodiment, the rectenna element 4 is set to the minimum manufacturable value of 0.91 wavelength, and the radius of the cylindrical rectenna 1 is 71 mm. Also, the number of rectenna elements 4 is not particularly limited to one row, and a plurality of rows may be arranged in the cylindrical axis direction (vertical direction in FIG. 1) of the cylindrical rectenna 1. The rectenna elements 4 may be arranged in various patterns such as shapes.

The shape of the cylindrical conductor 3 is not particularly limited to a perfect cylindrical shape, but may be a polygonal shape approximating a cylinder as long as it has a substantially cylindrical shape. For example, nine rectenna elements may be used. In the case of arrangement, a regular nine prism may be used.

FIG. 2 is a schematic perspective view showing a mechanical configuration of rectenna element 4 shown in FIG. The rectenna element 4 shown in FIG. 2 includes a circular patch antenna (circular microstrip antenna: CMSA) 11, a feed pin 12, and a rectifier circuit 13.

The circular patch antenna 11 is for producing a circular patch on a dielectric substrate having a thin ground plate of about 1/20 wavelength and operating it as a resonator. It functions as an antenna having directivity in the normal direction to the substrate. The circular patch antenna 11 thus formed can mechanically form an extremely thin antenna.

In this embodiment, the circular patch antenna 1
The polarization of 1 is linear polarization in the cylindrical radial direction, the relative dielectric constant of the substrate of the circular patch antenna 11 is 2.17, and the patch radius is 9.6 mm. Note that the antenna is not particularly limited to the above-mentioned circular patch antenna, and other antennas such as a rectangular patch antenna may be used as long as the antenna has a thin shape and has directivity in the normal direction to the substrate. You can also.

The feeding pin 12 is connected to the circular patch antenna 11
Is a small conductor rod used for pin feeding, and guides the microwave incident on the circular patch antenna 11 to the rectifier circuit 13 on the back surface.

As shown, the rectifier circuit 13 is formed on the back surface of the rectenna element 4 and is a circuit for converting microwaves received by the circular patch antenna 11 into DC power.
It comprises an input filter 14, a diode 15, and an output filter 16.

The input filter 14 generates a harmonic that is an integral multiple of the frequency of the fundamental wave when the microwave incident from the circular patch antenna 11 is rectified by the diode 15. The wave is prevented from flowing back to the circular patch antenna 11 and being re-emitted to cause radio interference. As the input filter 14, for example,
A low-pass filter using a fundamental wave as a pass band and a harmonic as a stop band is used.

The diode 15 converts a microwave inputted through the input filter 14 into a direct current. For example, a Schottky barrier diode which operates well in a microwave region is used.

The output filter 16 removes a fundamental wave and a harmonic generated at the time of rectification by the diode 15 and outputs DC power to the corresponding output wire among the output wires O1 to OM via the DC output terminal 17. As the output filter 16, for example, a filter having a pass band of direct current and a stop band of fundamental waves and harmonics is used.

FIG. 3 is a block diagram showing an electrical configuration of rectenna element 4 shown in FIG. 2. Rectenna element 4 shown in FIG. 2 is electrically configured as shown in FIG.

As shown in FIG. 3, the circular patch antenna 1
The microwave is received from 1, and the received microwave is rectified by the diode 15 via the input filter 14. At this time, the input filter 14 prevents the harmonic generated in the diode 15 from flowing back to the circular patch antenna 11, removes the fundamental wave and the harmonic by the output filter 16, and outputs only DC to the DC output terminal 17. Then, DC power is output.

Next, as described above, in this embodiment,
Since the plurality of rectenna elements 4 are arranged at equal intervals in the radial direction of the cylinder at a predetermined pitch on the cylindrical side surface of the cylindrical conductor 3, the rectenna element having the maximum DC power with respect to the microwave incident at an arbitrary incident angle. Is always at least one,
Even if the incident angle of the microwave changes, the change in output power can be minimized. As a result, a cylindrical device,
For example, it can be easily attached to a cylindrical articulated robot for space or the like, and the fluctuation of the output power can be minimized even if the incident angle of the microwave fluctuates.

In this embodiment, the rectenna element 4 corresponds to a rectenna element, the cylindrical conductor 3 corresponds to a cylindrical support, the output power detection and switch control circuit 2, and the switches S1 to SM correspond to parallel connection means. Switch S1
SM corresponds to the switch means, and the output power detection and switch control circuit 2 corresponds to the detection means and control means.

The operation of the power receiving device configured as described above will be described. When a plurality of rectenna elements 4 are arranged on the cylindrical side surface of the cylindrical conductor 3 as described above, the output power of each rectenna element 4 differs for each element, and if all rectenna elements 4 are simply connected in parallel, the output power Decreases.
Therefore, in the present embodiment, the output power is increased by connecting only a predetermined rectenna element from a plurality of rectenna elements 4 in parallel as described below.

First, when a predetermined microwave is transmitted to the cylindrical rectenna 1, each rectenna element 4 receives the microwave and outputs DC power to the corresponding output wires O1 to OM by the rectification circuit 13. Load resistances R1 to RM are individually connected to the output wires O1 to OM, respectively. The output power detection and switch control circuit 2
, The output power of each rectenna element 4 is detected.

Output power detection and switch control circuit 2
Turns on the corresponding one of the switches S1 to SM in order to connect only a predetermined number of rectenna elements including the rectenna element having the maximum DC power based on the detected output power of each rectenna element 4 in parallel. As a result, a predetermined number of rectenna elements including the rectenna element having the maximum DC power among the plurality of rectenna elements 4 are connected in parallel, and large output power can be generated.

Next, an example of the parallel connection processing by the output power detection and switch control circuit 2 will be described. Normally, the output of the rectenna element on both sides of the rectenna element where the output power is maximum has the next largest DC power after the DC power of the rectenna element where the output power is maximum. The output power can be increased by connecting another rectenna element adjacent to the rectenna element and the rectenna element having the maximum DC power in parallel.

FIG. 4 is a flow chart for explaining an example of the parallel connection processing by the output power detection and switch control circuit 2. In the following processing, the total number of rectenna elements 4 is M, the number of parallel elements, which is the number of rectenna elements 4 connected in parallel, is N, and 1 to M Are individually assigned, and M is added to the calculation result when the minimum value of the calculation result is smaller than 1, and M is subtracted from the calculation result when the maximum value of the calculation result is larger than M. Shall be. The quotient symbol (/) is a quotient converted to an integer and represents the largest integer that does not exceed the absolute value of the mathematical quotient. For example,
3/5 becomes 0, and -7/5 becomes -1. The function Pout (x) represents the output power of the rectenna element having the number of the argument x at the time of individual load.

As shown in FIG. 4, first, in step S1, the output power detection and switch control circuit 2 substitutes the number of parallel elements for N, substitutes the total number of elements for M, and sets the maximum output at the individual load. Substitute I for the number of the rectenna element of the power.

Next, in step S2, the DC power detection and switch control circuit 2 determines whether or not the number N of parallel elements is an odd number. If the number N is an odd number, the process proceeds to step S3. Transition.

If the number N of parallel elements is an odd number, step S3
In the output power detection and switch control circuit 2,
Substitute I-N / 2 into A and I + N / 2 into B.

Next, in step S4, the output power detection and switch control circuit 2 closes all the switches between the output wires from A to B and (IN) on both sides of the rectenna element having the maximum output power. / 2) to (I + N /
N rectenna elements 4 up to 2) are connected in parallel.

On the other hand, if N is an even number, in step S5, the output power detection and switch control circuit 2
It is determined whether or not ut (IN / 2)> Pout (I + N / 2), and Pout (IN / 2)> Pout (I
+ N / 2), the process proceeds to step S6, and Pout
If (I−N / 2)> Pout (I + N / 2) is not satisfied, the process proceeds to step S7.

Pout (IN / 2)> Pout (I +
In the case of (N / 2), in step S6, the output power detection and switch control circuit 2 substitutes IN / 2 for A and I + N / 2-1 for B.

Next, in step S4, the output power detection and switch control circuit 2 closes all the switches between the output wires A to B, and is disposed on both sides of the rectenna element having the maximum output power ( (I−N / 2) to (I + N / 2-1) excluding (I + N / 2) rectenna elements having small DC power among the (N + 1) rectenna elements
Up to N rectenna elements 4 are connected in parallel.

On the other hand, Pout (IN / 2)> Pout
If not (I + N / 2), in step S7, the output power detection and switch control circuit 2
1 is assigned to A, and I + N / 2 is assigned to B.

Next, in step S4, the output power detection and switch control circuit 2 closes all the switches between the output wires from A to B, and is disposed on both sides with the rectenna element of the maximum output power as the center ( Excluding (IN / 2) rectenna elements having small DC power among (N + 1) rectenna elements, (IN / 2 + 1) to (I + N / 2)
Up to N rectenna elements 4 are connected in parallel.

According to the above processing, when N is an odd number, N rectenna elements arranged on both sides around the rectenna element having the maximum DC power are connected in parallel, and when N is an even number, Of the (N + 1) rectenna elements arranged on both sides of the rectenna element having the largest power, N rectenna elements excluding the rectenna element at the end portion having the smaller DC power are connected in parallel. Therefore, regardless of whether the number of rectenna elements connected in parallel is odd or even, it is possible to connect N rectenna elements in parallel starting with the largest DC power, and to always generate a large output power. it can.

In the above example, the other rectenna element adjacent to the rectenna element having the maximum DC power and the rectenna element having the maximum DC power are connected in parallel.
Depending on the transmission state of the microwave, etc., the DC power of another rectenna element farther from the rectenna element having the maximum DC power than the rectenna element adjacent to the rectenna element having the maximum DC power may be larger than the rectenna element having the maximum DC power. Alternatively, the rectenna elements having larger DC power may be connected in parallel in order.

Next, the optimum value of the number N of parallel elements that can maximize the output voltage will be described. FIG. 5 is a diagram illustrating a relationship between the number N of parallel elements and the average output power when the total number M of the rectenna elements 4 is 5 to 30. The average output power shown in FIG. 5 has an incident power flux density (P _fd ) of 2065 W / m ² and a patch radius b of 9.6.
The average output power (W) on the horizontal plane in the case of mm is shown, and each average output power is a simulation value in consideration of the variation of the current-voltage characteristics of the rectenna element by an experimental value.

As shown in FIG. 5, there is a parallel element number N (the value indicated by a black square in the figure) at which the average output power is maximum with respect to the total element number M. The number N of parallel elements at the time of output is as shown in FIG. For example,
When 5 ≦ M ≦ 9, N = 2, and when 10 ≦ M ≦ 13, N = 3. Similarly, as the range of the total number of elements M increases, the number N of parallel elements at the maximum output increases. Increase in order.

From the above results, the relationship between the total number M of elements and the number N of parallel elements at the maximum output is such that for any M, N is [0.2M] or more and [0.4M + 1] or less ( here,
[X] is a Gaussian symbol and represents the largest integer not exceeding x). Therefore, when the number of the plurality of rectenna elements is M, [0.2M] or more and [0.4
It is preferable to connect two or more rectenna elements in parallel within the range of (M + 1) or less, and in this case, the output voltage can always be maximized.

The power receiving device of the present invention is preferably applied to a cylindrical articulated robot for space use, but is not particularly limited to this example. The power receiving device used for microwave power transmission for various applications. Can be similarly applied.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a power receiving device according to an embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a mechanical configuration of the rectenna element shown in FIG.

FIG. 3 is a block diagram showing an electrical configuration of the rectenna element shown in FIG. 2;

FIG. 4 is a flowchart illustrating an example of a parallel connection process performed by an output power detection and switch control circuit.

FIG. 5 is a diagram showing the relationship between the number N of parallel elements and the average output power when the total number M of rectenna elements is 5 to 30.

FIG. 6 is a diagram showing the number N of parallel elements at the time of maximum output for each range of the number M of all elements.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical rectenna 2 Output power detection and switch control circuit 3 Cylindrical conductor 4 Rectenna element 11 Circular patch antenna 12 Feeding pin 13 Rectifier circuit 14 Input filter 15 Diode 16 Output filter 17 DC output terminal O1-OM Output wire S1-SM switch R1 ~ RM Load resistance

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshihiko Mizuguchi 2-1-2 Koikodai, Seika-cho, Soraku-gun, Kyoto F-term in ATR Co., Ltd. Environmentally Adaptive Communication Laboratory (Reference) 5H006 CA07 CB00 CC01 CC04 HA05 HA08

Claims (7)

[Claims] 1. A power receiving device, wherein a plurality of rectenna elements for receiving microwaves and converting them into DC power are arranged on a cylindrical side surface of a cylindrical support having a substantially cylindrical shape. 2. The power receiving device according to claim 1, wherein the plurality of rectenna elements are arranged at equal intervals in a cylindrical radial direction at a predetermined pitch on a cylindrical side surface of the cylindrical support. 3. A rectenna element having a maximum DC power among the plurality of rectenna elements is connected in parallel with some other rectenna elements, and parallel connection means for outputting DC power is further provided. The power receiving device according to claim 1. 4. The parallel connection means outputs a DC power by connecting a rectenna element having a maximum DC power among the plurality of rectenna elements in parallel with another rectenna element adjacent to the rectenna element. The power receiving device according to claim 3, wherein 5. When the number of rectenna elements connected in parallel among the plurality of rectenna elements is N, and when N is an odd number, the parallel connection means centers around the rectenna element having the largest DC power. N rectenna elements arranged on both sides are connected in parallel, and when N is an even number, the rectenna elements having the largest DC power are arranged on both sides (N
5. The power receiving device according to claim 4, wherein N rectenna elements of the +1) rectenna elements are connected in parallel except for the rectenna element on the side of the end having a small DC power. 6. The parallel connection means, wherein when the number of the plurality of rectenna elements is M, [0.2M] or more and [0.4M + 1] or less (where [x] is a Gaussian symbol) The power receiving device according to any one of claims 3 to 5, wherein two or more rectenna elements are connected in parallel within a range of a maximum positive number that does not exceed x and a DC power is output. apparatus. 7. The parallel connection means includes: a plurality of switch means for connecting the plurality of rectenna elements in parallel; a detection means for detecting DC power of each of the plurality of rectenna elements; Control means for controlling a connection operation of the plurality of switches so that a rectenna element having a maximum DC power according to a detection result and another part of the rectenna element are connected in parallel. The power receiving device according to claim 3.