JP2012023857A - Rectenna and power receiving system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rectenna capable of automatically detecting failure in rectification circuit while suppressing reradiation of a microwave injected into an antenna from the same antenna, and a power receiving system using the same.SOLUTION: A rectenna comprises receiving means (20) for receiving a microwave, first and second rectification circuits (34 and 36) that rectify the microwave received by the receiving means, and a hybrid circuit (22) configured so that the microwave flows in the same phase as is between the receiving means and the first rectification circuit while it flows with the phase delayed by 90° between the receiving means and the second rectification circuit.

Description

  The present invention relates to a rectenna and a power receiving system using the same, and more particularly to a rectenna that receives microwaves, rectifies them, and converts them into DC power, and a power receiving system using the same.

Conventionally, a rectenna apparatus that converts microwaves received by an antenna into direct current power (hereinafter referred to as DC power) is known, and various studies have been made (see Non-Patent Document 1). Such a rectenna device is expected to be used in a space solar power generation system and the like that have been studied in recent years.
A space solar power generation system is a solar panel that is mounted on an artificial satellite that collects sunlight, converts the generated power into microwaves, transmits them to the ground, and converts the microwaves received on the ground into power. And used as commercial power. The rectenna device used in this space solar power generation system arranges a large number of rectennas, for example, hundreds of millions of rectennas, in a region irradiated with microwaves, and collects DC power from each rectenna to collect large power Obtainable. Here, the frequency band used for microwave transmission is the 2.45 GHz band or the 5.8 GHz band.

As shown in FIG. 4, the conventional rectenna includes an antenna 50 that receives microwaves, an input filter 52 that blocks harmonics, a rectifier circuit 54 that rectifies microwaves, and a microwave rectified by the rectifier circuit 54. Is converted to DC power.
In the rectenna configured as described above, a diode is generally used as the rectifier circuit 54. In the rectifier circuit 54, harmonics are generated due to the nonlinearity of the diodes. Therefore, the input filter 52 blocks the harmonics. The harmonics are prevented from being re-radiated from the antenna 50. Further, the output filter 56 prevents the fundamental wave in the 2.45 GHz band or 5.8 GHz band and the harmonics generated in the rectifier circuit 54 from being radiated to the output side of the DC power.
The rectenna device can acquire desired DC power by connecting rectifier circuits in series or in parallel.

James Oliver Mcspadden, "Rectifying and Oscillating Integrated Antennas", Texas A & M University, August 1998

On the other hand, part of the fundamental wave input from the antenna 50 may be reflected by the input filter 52 or the rectifier circuit 54.
In this regard, in the conventional configuration as described above, since the input filter 52 needs to pass the fundamental wave, there is a problem that the reflected fundamental wave cannot be suppressed from being re-radiated from the antenna 50. is there. Since the rectenna device handles a large amount of power, even if the proportion of the reflected fundamental wave is small, the overall power is large and strong electromagnetic waves are re-radiated from the antenna to the space. is not.

Further, the cause of the failure of the rectenna is mainly the open failure or short-circuit failure of the diode which is the rectifier circuit 54, and the failure is detected by monitoring the output of the DC power. There is a problem that it is not possible to detect an open failure at a place where the parallel connection is made. As described above, since hundreds of millions of rectennas are arranged in the rectenna device, it is difficult to check the soundness of the entire power receiving system unless a failure is detected.
The present invention has been made to solve the above-described problems, and the object of the present invention is to automatically detect a failure of a rectifier circuit while suppressing re-radiation of microwaves incident on the antenna from the antenna. It is an object to provide a rectenna that can be used and a power receiving system using the rectenna.

  In order to achieve the above object, a rectenna according to claim 1 includes a receiving means for receiving a microwave, first and second rectifier circuits for rectifying the microwave received by the receiving means, the receiving means and the first rectifier. 1 and the second rectifier circuit is interposed between the receiving means and the first rectifier circuit, while the microwave flows in the same phase between the receiving means and the second rectifier circuit. And a hybrid circuit configured so that the microwave flows with a phase delayed by 90 °.

  A rectenna according to a second aspect is the rectenna according to the first aspect, wherein a first input filter is interposed between the hybrid circuit and the first rectifier circuit, and a second is interposed between the hybrid circuit and the second rectifier circuit. An input filter is interposed, and the first input filter and the second input filter block even-order harmonics.

  The rectenna according to a third aspect is the rectenna according to the first or second aspect, wherein the hybrid circuit is further connected to a detection circuit, and microwaves flow in the same phase between the detection circuit and the second rectifier circuit, The microwave is configured to flow between the detector circuit and the first rectifier circuit with a phase delayed by 90 °.

  According to a fourth aspect of the present invention, there is provided a power receiving system using the rectenna according to the third aspect, wherein the rectenna device in which one or a plurality of the rectennas are arranged, and the DC power connected to the rectenna device and converted by the rectennas. Current collecting circuit, DC-AC converting means connected to the current collecting circuit, converting DC power to AC power and transmitting to the commercial power network, and monitoring means connected to the detection circuit of each rectenna The monitoring means includes first and second rectennas based on a voltage value detected from a synthesized wave obtained by synthesizing the fundamental waves of the microwaves reflected from the first and second rectifier circuits by the detector circuits. A failure of the second rectifier circuit is detected.

According to the rectenna of claim 1, the microwave flows in the same phase between the receiving means and the first rectifier circuit, while the microwave delays the phase by 90 ° between the receiving means and the second rectifier circuit. A hybrid circuit configured to flow;
Therefore, the fundamental wave of the microwave input from the receiving means is reflected by the first rectifier circuit and the second rectifier circuit, and the fundamental wave reflected from the second rectifier circuit passes through the hybrid circuit and is received at the receiving means end. Since the fundamental wave reflected from the first rectifier circuit is combined and canceled in opposite phases, the fundamental wave is prevented from being re-radiated from the receiving means, and the influence of electromagnetic waves on the surrounding environment is suppressed. Can do.

  Of the harmonics generated in the first rectifier circuit and the second rectifier circuit, odd-order harmonics generated in the second rectifier circuit pass through the hybrid circuit and are generated in the first rectifier circuit at the receiving means end. Since the opposite harmonics of the harmonics of the same order are combined and cancel each other out, odd harmonics can be prevented from being re-radiated from the receiving means, and the influence of electromagnetic waves on the surrounding environment can be suppressed. Can be suppressed.

  According to the rectenna of claim 2, the first input filter is interposed between the hybrid circuit and the first rectifier circuit, the second input filter is interposed between the hybrid circuit and the second rectifier circuit, Since the first input filter and the second input filter block even-order harmonics, the circuit configurations of the first and second input filters can be simplified.

  According to the rectenna of the third aspect, the hybrid circuit is further connected to the detection circuit, and the microwave flows between the detection circuit and the second rectification circuit while maintaining the same phase, while the detection circuit and the first rectification circuit Since the microwave flows between the first rectifier circuit and the second rectifier circuit through the hybrid circuit, the synthesized wave is synthesized by being input to the detector circuit through the hybrid circuit. The voltage is converted by RF-DC conversion.

  That is, when the first and second rectifier circuits are normal, a part of the fundamental wave is reflected, and when the first or second rectifier circuit is abnormal, the entire fundamental wave is reflected, and at least the first and second rectifier circuits are reflected. Since the voltage converted by the detection circuit when either one of the second rectifier circuits is abnormal becomes larger than that when the detector circuit is normal, it is possible to determine the state of the first and second rectifier circuits from the voltage. .

  According to the power receiving system using the rectenna according to claim 4, the rectenna apparatus in which one or a plurality of rectennas are arranged, and the monitor means to which the detection circuit of each rectenna is connected, the monitor means is connected to each detection circuit. Since the failure of the first and second rectifier circuits of each rectenna is automatically detected from the value of the voltage detected by combining the fundamental waves reflected from the first and second rectifier circuits, the soundness of the power receiving system can be easily Can be confirmed.

It is a schematic block diagram of a space solar power generation system including a power receiving system in which a rectenna according to the present invention is installed. It is a schematic block diagram of a power receiving system. It is a block diagram which shows the circuit of a rectenna. It is a block diagram which shows the circuit of the conventional rectenna.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a space solar power generation system including a power receiving system in which a rectenna according to the present invention is installed.
As shown in FIG. 1, the power generation satellite 1 is introduced into, for example, a geostationary orbit, collects sunlight in outer space to generate electric energy, and converts the generated electric energy into microwaves to generate the power generation satellite 1. It transmits to the ground power base 4 using the attached transmission antenna 2. Here, in FIG. 1, the power generation satellite 1 is configured by only one unit, but the power generation satellite 1 may be configured by a plurality of units.

A power receiving system 6 is configured in the power base 4, and the power receiving system 6 includes a rectenna device 8. The microwave that is RF power transmitted from the power generation satellite 1 is received by the rectenna device 8, and the received microwave is converted into DC power and transmitted to the existing commercial power network via the power transmission cable 10. The frequency band used for microwave transmission is the 2.45 GHz band or the 5.8 GHz band.
Thus, since the distance from the power generation satellite 1 to the power base 4 is very long, the diameter of the transmission antenna 2 may reach several kilometers, and the diameter of the rectenna device 8 arranged in the power base 4 is also several kilometers. It may reach.

The configuration of the power receiving system 6 in such a space solar power generation system will be described with reference to FIG.
FIG. 2 is a block diagram showing a configuration of power reception system 6 shown in FIG.
The rectenna device 8 is configured by arranging n rectennas 12 (n is 1 or more), and the rectenna device 8 includes a current collecting circuit 14 and a monitor unit (monitoring means) 16 for displaying the operation status of the rectenna device 8. Is connected. A DC-AC converter 18 that converts DC power to AC power (hereinafter referred to as AC power) is connected to the current collecting circuit 14, and is connected to the commercial power network via the power transmission cable 10 for power transmission.

  In the power receiving system 6 configured as described above, the DC power converted by rectifying the microwaves received by each rectenna 12 is collected to the current collecting circuit unit 14. The DC power collected by the current collecting circuit 14 is converted into AC power by the DC-AC converter 18 and transmitted from the power transmission cable 10 to the commercial power network.

FIG. 3 shows a block diagram of the rectennas 12 arranged in the rectenna device 8.
The rectenna 12 includes a receiving antenna (receiving means) 20 that receives microwaves, a 3 dB hybrid circuit (hybrid circuit) 22, capacitors 24, 26, and 28, a first input filter 30, a second input filter 32, and a first rectifier circuit 34. , A second rectifier circuit 36, a first output filter 38, a second output filter 40, and a monitor circuit (detection circuit) 42.
The receiving antenna 20 is connected to the first terminal 22a of the 3 dB hybrid circuit 22 and receives microwaves.

  The 3 dB hybrid circuit 22 has a first terminal 22a as an input terminal, a second terminal 22b, a third terminal 22c, and a fourth terminal 22d as output terminals. When the wavelength of the fundamental wave is λ, each side Is composed of a line 22e having a length of λ / 4 coupled in a square shape. The microwave input from the first terminal 22a passes through the line 22e and is equally divided, and is output to the second terminal 22b and the third terminal 22c. The microwave output to the third terminal 22c is delayed in phase by 90 ° with respect to the microwave output to the second terminal 22b. The microwave input from the first terminal 22a is not output to the fourth terminal 22d.

  DC cut capacitors 24 and 26 are connected between the second terminal 22b and the first input filter 30, and between the third terminal 22c and the second input filter 32, respectively. This is to prevent the DC power converted by the first output filter 38 and the second output filter 40 described later from being output to the receiving antenna 20 and the monitor circuit 42 side.

  The first input filter 30 and the second input filter 32 pass the microwave incident from the receiving antenna 20, that is, the fundamental wave of 2.45 GHz band or 5.8 GHz band, and the first rectifier circuit 34 and the second rectifier circuit 36. The harmonics generated in is cut off. Specifically, although not shown, the first input filter 30 and the second input filter 32 are a plurality of open stubs in which the electrical length of the line becomes a quarter wavelength at the even harmonic frequency to be cut off, and each open stub. And the even-order harmonics are blocked by the open stub.

The first rectifier circuit 34 and the second rectifier circuit 36 rectify the microwaves that have passed through the first input filter 30 and the second input filter 32.
The first output filter 38 connected to the first rectifier circuit 34 and the second output filter 40 connected to the second rectifier circuit 36 are rectified by the first rectifier circuit 34 and the second rectifier circuit 36. The microwave is converted into DC power and output to the output terminal 41. In addition, the fundamental wave and harmonics are cut off. The DC power converted by the first output filter 38 and the second output filter 40 is collected to the current collecting circuit 14 via the output terminal 41.

  The fourth terminal 22d and the monitor circuit 42 are connected via a DC cut capacitor 28. The monitor circuit 42 detects the fundamental wave reflected by the first rectifier circuit 34 and the second rectifier circuit 36. The monitor circuit is a detection circuit based on a rectification method, and converts a fundamental wave reflected by RF-DC conversion into a detection voltage (voltage). The DC cut capacitor 28 is provided to prevent the detection voltage converted by the monitor circuit 42 from being output to the reception antenna 20, the first rectifier circuit 34, and the second rectifier circuit 36 side. Each monitor circuit 42 is connected to the monitor unit 16 and can be monitored by the monitor unit 16.

The operation of the rectenna 12 according to the present invention thus connected will be described below.
The microwave transmitted from the transmission antenna 2 is applied to the reception antenna 20. The fundamental wave input from the receiving antenna 20 is input from the first terminal 22 a of the 3 dB hybrid circuit 22. The fundamental wave is divided into two by the 3 dB hybrid circuit 22, and one fundamental wave passes through the capacitor 24 and the first input filter 30 and is input to the first rectifier circuit 34. The other fundamental wave divided into two passes through the capacitor 26 and the second input filter 32 and is input to the second rectifier circuit 36. Here, since the third terminal 22c is output from the first terminal 22a through the line 22e having a length of λ / 4, the phase of the fundamental wave input to the second rectifier circuit 36 is the first. Delayed by 90 ° with respect to the fundamental wave input to one rectifier circuit.

The fundamental waves input to the first rectifier circuit 34 and the second rectifier circuit 36 are rectified and input to the first output filter 38 and the second output filter 40, respectively. On the other hand, the first rectifier circuit 34 and the second rectifier circuit 36 generate fundamental wave reflections and harmonics.
First, the fundamental wave reflected by the first rectifier circuit 34 and the second rectifier circuit 36 passes through the first input filter 30 and the second input filter 32, and the 3 dB hybrid circuit from the second terminal 22b and the third terminal 22c, respectively. 22 is divided into two and output to the receiving antenna 20 and the monitor circuit 42. The phase of the reflected fundamental wave input from the second terminal 22b does not change at the receiving antenna 20 end, but the reflected fundamental wave input from the third terminal 22c passes through the line 22e having a length of λ / 4. Therefore, the phase at the receiving antenna 20 end is 180 ° behind the fundamental wave reflected by the first rectifier circuit 34, that is, the phase is reversed, and the fundamental waves reflected at the receiving antenna 20 end are combined and cancel each other. Therefore, re-radiation from the receiving antenna 20 is suppressed.

  Next, the harmonics generated by the first rectifier circuit 34 and the second rectifier circuit 36 are blocked from passing even-order harmonics by the first input filter 30 and the second input filter 32, so that odd-order harmonics are generated. The wave passes through the first input filter 30 and the second input filter 32 and is input to the 3 dB hybrid circuit 22 from the second terminal 22 b and the third terminal 22 c, and is divided into two and input to the receiving antenna 20 and the monitor circuit 42. The The phase of the odd-order harmonics input from the second terminal 22b does not change at the receiving antenna 20 end, but the odd-order harmonics input from the third terminal 22c pass through the line 22e having a length of λ / 4. Therefore, the phase of the receiving antenna 20 is delayed by 180 ° from the same-order harmonics of the first rectifier circuit 34, that is, the phase is reversed and synthesized at the receiving antenna 20 to cancel each other, so that re-radiation is suppressed. .

  The fundamental wave reflected by the first rectifier circuit 34 and the second rectifier circuit 36 is divided into two by the 3 dB hybrid circuit 22 and input to the monitor circuit 42. The reflected fundamental wave detected by each monitor circuit 42 is input to the monitor unit 16, and the monitor unit 16 detects a failure of each rectenna 12. Here, the failure detection of the first rectifier circuit 34 and the second rectifier circuit 36 using the monitor circuit 42 will be described below.

  When the first rectifier circuit 34 and the second rectifier circuit 36 are normal, a part of the fundamental wave is reflected from the first rectifier circuit 34, and the reflected fundamental wave passes through the λ / 4 line 22 e and is received by the receiving antenna. The phase is delayed by 90 ° with respect to the fundamental wave input from 20 and input to the monitor circuit 42. Since the phases of some of the fundamental waves reflected from the second rectifier circuit 36 do not change, the fundamental waves reflected from the first rectifier circuit 34 and the second rectifier circuit 36 at the monitor circuit 42 end have the same phase and are reflected. The signal intensity of the synthesized wave obtained by synthesizing the fundamental wave is approximately equal to the signal intensity of all reflected fundamental waves.

  When the first rectifier circuit 34 or the second rectifier circuit 36 has an open failure or a short-circuit failure, all the fundamental waves are reflected from the failed rectifier circuit of the first rectifier circuit 34 or the second rectifier circuit 36. It becomes larger than the detection voltage when the first rectifier circuit 34 and the second rectifier circuit 36 are normal.

  In addition, when the first rectifier circuit 34 and the second rectifier circuit 36 have an open fault or a short fault, all the fundamental waves are reflected from the first rectifier circuit 34 and the second rectifier circuit 36, and the detection voltage is the first rectifier. It becomes larger than the detection voltage when the circuit 34 and the second rectifier circuit 36 are normal.

When the detection voltage detected by the monitor circuit 42 is larger than a specified value, the monitor unit 16 determines that the rectifier circuit has failed and detects the failure.
The microwaves rectified by the first rectifier circuit 34 and the second rectifier circuit 36 are converted into DC power by the first output filter 38 and the second output filter 40, and are collected by the current collector circuit 14.

  Thus, according to the rectenna according to the present invention, the microwave input from the receiving antenna 20 to which the first terminal 22a of the 3 dB hybrid circuit 22 is connected is connected to the second terminal 22b that is output in the same phase. A first rectifier circuit 34 and a second rectifier circuit 36 connected to a third terminal 22c that outputs a phase of the microwave input from the receiving antenna 20 with a delay of 90 ° are provided.

  Therefore, the fundamental wave of the microwave input from the receiving antenna 20 is divided into two by the 3 dB hybrid circuit 22 and is equally input to the first rectifier circuit 34 and the second rectifier circuit 36, and is input to the second rectifier circuit 36. The phase of the fundamental wave is delayed by 90 ° with respect to the phase of the first rectifier circuit 34, and the fundamental wave reflected by the second rectifier circuit 36 passes through the 3 dB hybrid circuit 22, thereby causing the first rectifier circuit at the end of the receiving antenna 20. Since it is in antiphase with the fundamental wave reflected by 34 and is combined and canceled, re-radiation from the receiving antenna 20 is suppressed.

The odd-order harmonics pass through the first input filter 30 and the second input filter 32, but the odd-order harmonics generated by the second rectifier circuit 36 pass through the 3 dB hybrid circuit 22 to be subjected to the first rectification. Since the same-order harmonics generated in the circuit 34 have an opposite phase at the receiving antenna 20 end, they are combined at the receiving antenna 20 end to cancel and re-radiate.
Thereby, the influence of electromagnetic waves on the surrounding environment can be suppressed.

  Further, among the harmonics generated by the first rectifier circuit 34 and the second rectifier circuit 36, the odd-order harmonics are synthesized and canceled by the hybrid circuit 22 as described above, so that the first input filter 30 and the second The input filter 32 only needs to block even-order harmonics, and the first input filter 30 and the second input filter 32 can have a simple circuit configuration.

  Further, by connecting the monitor circuit 42 to the fourth terminal 22d of the 3 dB hybrid circuit 22, the fundamental wave reflected by the first rectifier circuit 34 and the second rectifier circuit 36 passes through the 3 dB hybrid circuit 22 and passes through the monitor circuit 42. Is input. When the first rectifier circuit 34 or the second rectifier circuit 36 has an open fault or a short fault, all the fundamental waves are reflected from the faulty rectifier circuit, and detection is performed by converting a synthesized wave obtained by synthesizing the reflected fundamental waves. The voltage is larger than the detection voltage detected by the monitor circuit 42 when the first rectifier circuit 34 and the second rectifier circuit 36 are normal. In addition, when the first rectifier circuit 34 and the second rectifier circuit 36 have an open failure or a short-circuit failure, all the fundamental waves are reflected from the first rectifier circuit 34 and the second rectifier circuit 36, and thus are detected by the monitor circuit 42. The detected voltage becomes larger than the detected voltage when the first rectifier circuit 34 and the second rectifier circuit 36 are normal.

  Therefore, the monitor unit 16 to which each monitor circuit 42 is connected receives the detection voltage detected by each monitor circuit 42 and thereby determines that the monitor circuit 42 that has output a detection voltage larger than a specified value is faulty. Therefore, automatic failure detection of the first rectifier circuit 34 and the second rectifier circuit 36 provided in each rectenna 12 becomes possible, and the soundness confirmation of the power receiving system 6 becomes easy.

Although the description of the embodiment is finished as described above, the present invention is not limited to the above-described embodiment.
For example, in the above embodiment, the case where it is used in a space solar power generation system has been described, but the present invention is not limited to this.

DESCRIPTION OF SYMBOLS 1 Power generation satellite 4 Electric power base 6 Power receiving system 8 Rectenna device 12 Rectenna 16 Monitor part (monitor means)
20 Receiving antenna (receiving means)
22 3dB hybrid circuit (hybrid circuit)
22a 1st terminal 22b 2nd terminal 22c 3rd terminal 22d 4th terminal 30 1st input filter 32 2nd input filter 34 1st rectifier circuit 36 2nd rectifier circuit 42 Monitor circuit (detection circuit)

Claims (4)

Receiving means for receiving microwaves;
First and second rectifier circuits for rectifying microwaves received by the receiving means;
Between the receiving means and the first and second rectifier circuits, microwaves flow in the same phase between the receiving means and the first rectifier circuit, while the receiving means and the second rectifier circuit. A hybrid circuit configured such that the microwave flows between the rectifier circuit and the phase delayed by 90 °;
Rectena, characterized by having A first input filter is interposed between the hybrid circuit and the first rectifier circuit, and a second input filter is interposed between the hybrid circuit and the second rectifier circuit,
The rectenna according to claim 1, wherein the first input filter and the second input filter block even-order harmonics. The hybrid circuit is:
Furthermore, it is connected to the detection circuit,
The microwave flows in the same phase between the detection circuit and the second rectifier circuit, while the microwave flows between the detection circuit and the first rectifier circuit with a phase delayed by 90 °. The rectenna according to claim 1 or 2, characterized in that. A rectenna device in which one or a plurality of the rectennas are arranged;
A current collecting circuit that is connected to the rectenna device and collects DC power converted by each rectenna;
DC-AC conversion means connected to the current collecting circuit, converting DC power to AC power and transmitting the AC power to a commercial power supply network;
Monitoring means to which the detection circuit of each rectenna is connected,
The monitoring means includes first and second rectifier circuits of each rectenna based on a voltage value detected from a combined wave obtained by combining the fundamental waves of the microwaves reflected from the first and second rectifier circuits by the detector circuits. The power receiving system using the rectenna according to claim 3, wherein a malfunction of the rectenna is detected.

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