JPH06233480A - Rectenna apparatus - Google Patents

Abstract

PURPOSE:To prevent breakdown of a rectifying diode by connecting a circuit which connects in series an auxiliary power supply and a switch in parallel with a rectenna element and then inserting a rectifying diode between the rectenna element and its output end. CONSTITUTION:In the case a rectenna element 1 has received a microwave signal while a switch 4 is turned on and an auxiliary power supply 2 drives a motor 6, if an output voltage of the rectenna element 1 does not exceed a voltage of the auxiliary power supply 2, a rectifying diode 3 is turned off. Therefore, an output end of the rectenna element 1 is opened but an output voltage of the rectenna element 1 is lower than the voltage which results in breakdown of the rectifying diode 3. Moreover, if an output voltage of the rectenna element 1 has exceeded a voltage of the auxiliary power supply 2, the rectifying diode turns on and the rectenna element 1 is connected with a motor 6. Thereby, breakdown of the rectifying diode 3 can be prevented while the rectenna element 1 and auxiliary power supply 2 are switched.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A rectenna device receives microwaves and receives D
This is a device for converting to C power, and its application is being considered for a solar power generation satellite system, a stratospheric wireless relay system, and the like. The solar power generation satellite system is a system that converts solar energy received by a solar cell mounted on the satellite into microwaves, transmits the microwaves to the ground, and receives the microwaves by a rectenna device on the ground to convert the microwaves into DC power. The stratospheric wireless relay system is a system in which an unmanned airplane equipped with a rectenna device is used instead of a satellite as a repeater for communication, and the unmanned airplane can continue to fly by using microwaves from the ground as an energy source.

Generally, this rectenna device has a structure in which a large number of rectenna elements are arranged in a region irradiated with microwaves, and a large amount of electric power can be taken out by combining the DC outputs from the individual rectenna elements.

First, as shown in FIG. 3, the rectenna element includes an antenna section 11 for receiving microwaves, a diode 12 for rectifying microwaves, an input filter 13 for blocking harmonics generated from the diode 12, and a diode. An output filter 14 for converting the signal rectified by 12 into DC power and an output end 15 for outputting DC power. Then, by connecting the load 16, DC power is supplied from the output end 15. The RF frequency generally used for power transmission is the 2.45 GHz band.

FIG. 4 shows a concrete example of the structure of the rectenna element.
Shown in. The antenna unit 11 is composed of a circular conductor, and the microwaves received here are coupled by a slot. The signal rectified by the diode 12 is D by the output filter 14.
It is converted into C power and transmitted to the output terminal 15. The input filter 13 is provided to prevent unnecessary harmonics generated in the diode from re-radiating from the antenna section.

By the way, when this rectenna element is used as a power source for an unmanned aerial vehicle or the like, it is conceivable to provide a standby power source inside the rectenna device, assuming that microwaves cannot be received.

For example, assuming that an unmanned aerial vehicle receives microwaves from the ground to receive power supply for power, the rectenna elements are inevitably arranged on the ground side of the airframe. However, if the rectenna device is placed under the fuselage, it will be very difficult to receive microwaves during takeoff and landing of an unmanned aerial vehicle.
An effective means is to install a backup power supply and supply power from this backup power supply during takeoff and landing.

FIG. 5 shows a configuration example in which a load such as a motor is connected to the rectenna device in which the rectenna element and the standby power supply are provided together as described above. The rectenna device A includes a rectenna element unit 1 in which 1 to n rectenna elements are arranged according to a desired output power, a standby power source 2, and a switch 4 for switching between the rectenna element unit 1 and the standby power source 2. On the other hand, the load B connected to the rectenna device is composed of a driven motor 6 and a propeller 7 that is rotated by the motor 6 to generate a propulsive force.

At the time of takeoff and landing, the standby power source 2 and the motor 6 are connected by the switch 4 and used as a power source of the motor 6. After the airplane is ready to receive microwaves, the switch 4 is switched to connect the rectenna element and the motor, and the motor 6 is rotated by the electric power from the rectenna element.

However, when implementing such a drive system with the above-mentioned structure, the following problems occur. In order to start reception of microwaves, it is necessary to start microwave transmission after switching the switch from the standby power source side to the rectenna element side. When the microwave transmission is started without connecting the rectenna element and the load, the microwave is received with the output terminal of the rectenna element being in an open state (infinite resistance value), and unconsumed electromotive force is generated in the rectenna element. In particular, the rectifying diode 12 in the rectenna element
A large DC voltage is applied to both ends of the diode (see FIG. 3), and in the worst case, the diode 12 is destroyed by exceeding the reverse breakdown voltage of the diode 12.

In order to avoid this inconvenience, it is necessary to take measures in the entire power transmission system including the rectenna device so that power transmission is not performed when the output end of the rectenna element is in the open state. Therefore, a new control signal channel must be provided between the power receiving side and the power transmitting side, and the power transmission procedure must be controlled so that power transmission is started after confirming the safety of the receiving side. There is a risk that it will become larger and more complex. This tendency is contrary to the demand for smaller and lighter power receiving devices for airplanes.

[0012]

As described above, in the rectenna device provided with the rectenna element and the standby power source, when the power transmission is started without the load being connected to the output terminal of the rectenna element, the rectenna element is provided. An excessive reverse voltage is applied to the internal diode, which may damage the diode. The present invention provides a rectenna device that can be used for power transmission without the need for complicated power transmission processing procedures without fear of destruction of the diode.

[0013]

In order to solve this problem, in the present invention, an antenna element for receiving a microwave, a diode for rectifying the microwave received by the antenna element, and a diode for generating the same are generated. Outputs a DC signal converted by the rectenna element section and a rectenna element section in which a plurality of rectenna elements composed of an input filter for blocking harmonics and an output filter for converting the microwave rectified by the diode into a DC signal are arranged. In a rectenna device having an output terminal for connecting a standby power supply and a first switch element in series, the circuit is connected in parallel to the rectenna element section with respect to the output terminal, and the rectenna element section and the output terminal are connected. It is characterized in that a rectifier circuit is inserted between them.

In the second invention, the output voltage of the rectenna element section is larger than the output voltage of the standby power source, and the reverse withstand voltage characteristic of the diode forming the rectenna element section is the rectenna element section. It is characterized by being larger than the output voltage of.

In the third invention, a second switch element provided in parallel with the rectifier circuit, the first switch,
And a control means for controlling so that the second switch elements are respectively inverted and connected.

[0016]

In the present invention, the rectenna element section is connected to the output terminal of the rectenna device through the rectifying circuit regardless of the connection state of the switch of the switch means for connecting the output terminal of the rectenna device and the standby power source. It is characterized by That is, since the rectenna element portion is configured by using a diode having a reverse breakdown voltage higher than the output voltage of the rectenna element portion as a rectifying element, the load resistance seen from the rectenna element is infinite regardless of whether the switching timing of the switch means is correct or incorrect. Even in such a case, it is possible to prevent breakdown of the rectifying diode inside the rectenna element. Further, by providing the second switch means, it is possible to eliminate power waste in the rectifier circuit and supply power.

That is, according to the present invention, the switch is turned off.
When the rectenna element section receives microwaves while driving the motor with N as the standby power source, the diode is OFF when the output voltage Vr of the rectenna element section does not exceed the standby power source voltage Vg, so the output terminal of the rectenna is open. However, the output voltage Vr of the rectenna is the voltage Vb at which the diode is destroyed.
Since the diode is not destroyed, the diode is turned on when the output voltage Vr of the rectenna exceeds the backup power supply voltage Vg, so that the rectenna and the motor are connected and the diode is not destroyed. Further, by providing a switch that is interlocked with the switch provided in front of the standby power supply in parallel with the diode provided between the rectenna and the standby power supply, it is possible to eliminate power loss in the diode.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a rectenna device which is an embodiment of the present invention. In the same figure, 1 is a rectenna element part configured by arranging 1 to n rectenna elements according to a desired output power, 2 is a standby power source, 3 is a diode, 4 is a switch for turning on the standby power source, rectenna A rectenna device is constituted by the output terminal 5 for supplying electric power from the element part or the standby power supply.

A motor 6 serving as a load is connected to the output end 5, and the motor is driven by the electric power supplied from the rectenna element unit 1 and the auxiliary power source 2, and the propeller 7 connected to the rotating shaft of the motor rotates. And generate propulsion. The operating principle of this embodiment using the rectenna device of the present invention as a power source for an unmanned airplane will be described in detail with reference to FIG.

Since it is not necessary to drive the motor before starting the takeoff of the unmanned aerial vehicle, there is no power supply from the rectenna element part and no power supply from the standby power supply, so the switch 4 remains OFF. Is.

At the start of takeoff, it is difficult to supply electric power from the rectenna element unit, so the switch 4 is turned on to supply electric power from the standby power supply. In this way standby power supply 2
By this, the motor 6 is driven, the propeller 7 rotates, and propulsive force is generated, so that the unmanned aerial vehicle takes off.

Here, between the reverse voltage Vb at which the rectifying diode 12 (see FIG. 3) inside the rectenna element constituting the rectenna element 1 is destroyed, the maximum output voltage Vr of the rectenna element, and the standby power supply voltage Vg. Have the following relationships. Vb ≧ Vr ≧ Vg Since the output voltage of the rectenna element unit 1 is zero before the power transmission is started, the voltage Vg of the standby power supply is applied to the diode 3. Vg is a voltage in the opposite direction to the diode, and at this time, the diode 3 remains OFF, and no current flows in the diode 3.

Next, when the unmanned aerial vehicle is in a flight state at a certain altitude and the rectenna elements arranged on the ground side of the body are ready to receive microwaves from the ground side, the switch 4 is turned off, Start transmitting microwaves. The rectenna element section receives the microwave and converts it into a DC voltage, and the rectenna element section generates the output voltage Vr. Since the switch 4 is OFF, the voltage at the load side terminal of the diode 3 is zero, and the output voltage Vr of the rectenna element portion has a higher potential, a forward voltage is applied to the diode 3, The diode 3 is turned on, the current of the diode flows, power is supplied from the rectenna element unit 1, and the motor 6 is driven. This is the normal operating mode.

Here, a case will be described where microwave transmission is started while the motor 5 is being driven by the standby power supply 2. In the configuration of this embodiment, the switch 4 O
Regardless of N or OFF, the output terminal of the rectenna element is always connected to the load (motor) via the diode 3, and the load resistance at the output end becomes infinite as in the conventional rectenna device. A state where an excessive voltage is applied to the rectifying diode inside the element does not occur.

That is, when power is transmitted by microwaves with the switch 4 in the ON state, the output voltage Vr is generated in the rectenna element section 1. When Vr is smaller than the voltage Vg of the standby power supply, the diode 3 is reversely moved to (Vg-V
Since the voltage of r) is applied and Vr is applied to the diode 12 inside the rectenna element, the diode 3
Is kept OFF, the motor 5 is driven by the standby power supply 2.

On the other hand, when the output voltage Vr of the rectenna element portion becomes higher than the voltage Vg of the standby power source, a forward voltage is applied to the diode 3, so that the diode 3 is turned on and the rectenna 1 and the standby power source 2 are driven in parallel. By motor 5
Is driven. At this time, even if the switch 4 is turned off, it is only driven by the electric power generated in the rectenna element unit 1.

That is, regardless of the connection state of the switch 4,
In principle, diode 1 for rectification inside the rectenna element
No reverse voltage higher than the output voltage Vg of the standby power supply is applied to the secondary power supply 2, and the reverse DC voltage across the rectifying diode 12 in the rectenna element unit 1 does not exceed the reverse breakdown voltage. The diode 12 inside the element is not destroyed.

Next, a second embodiment of the present invention will be described. Here, a switch that bypasses the diode 3 and a switch for transmitting power of the standby power supply are interlocked and controlled.

The structure of the embodiment is shown in FIG. Rectenna element part 1, standby power supply 2, diode 3, switch 4 output end 5
Up to this point, the configuration is similar to that of the above-described embodiment. In addition to this, a switch 8 that bypasses the diode 3 and a control unit that controls the switch 8 and the switch 4 are provided. A switch 8 for bypassing the diode 3 is provided in parallel with the diode 3, and the switch 8 is opened when the switch 4 is connected, and conversely, the switch 8 is connected when the switch 4 is opened. Controls the switches 4 and 8. FIG. 2 shows that power is supplied in parallel from the rectenna element unit 1 and the standby power supply 2.

Here, when the switch 4 is turned off and the rectenna element section 1 is in a single power feeding operation state, the switch 8 is interlocked and turned on, and the DC current flowing through the diode 3 flows through the switch 8. Like In the above-described embodiment, the current flows through the diode 3 when the power is supplied from the rectenna element portion, so that there is a disadvantage that the power is wasted here. When the switch 4 is opened and the switch 8 is connected by providing the switch 8, the power loss in the diode 3 when the power is supplied from the rectenna element unit can be reduced.

In the above-described embodiment, the motor is used as the driving force generator connected to the rectenna device, but if the load and the driving force generator can use the DC power source as a power supply source, the above-mentioned embodiment is used. The present invention can be applied similarly to the example.

[0033]

According to the rectenna device of the present invention, even if the rectenna element receives microwaves by mistake while the motor is being driven by the standby power source, the diode forming the rectenna element is not destroyed and the rectenna element is not operated. There is no problem. Further, according to the second aspect of the invention, it is possible to eliminate the power loss in the diode which constitutes the rectenna element section.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of a rectenna device according to the present invention.

FIG. 2 is a diagram showing another configuration example of the rectenna device according to the present invention.

FIG. 3 is a diagram showing a configuration of a rectenna element used in a conventional rectenna device.

FIG. 4 is a diagram showing a configuration example of a conventional rectenna element.

FIG. 5 is a diagram showing a configuration of a conventional rectenna device.

[Explanation of symbols]

 1: Rectenna element part 2: Standby power supply 3: Diode 4: Switch 5: Output terminal

Claims (3)

[Claims] 1. An antenna element for receiving a microwave, a diode for rectifying the microwave received by the antenna element, an input filter for blocking harmonics generated by the diode, and a microwave rectified by the diode. In a rectenna device having a rectenna element section in which a plurality of rectenna elements each including an output filter for converting into a DC signal are arranged, and an output terminal for outputting a DC signal converted by the rectenna element section, a standby power source and a first switch A rectenna device, wherein a circuit in which elements are connected in series is connected in parallel to the rectenna element section with respect to the output terminal, and a rectifier circuit is inserted between the rectenna element section and the output terminal. 2. The output voltage of the rectenna element section is higher than the output voltage of the standby power source, and the reverse withstand voltage characteristic of the diode forming the rectenna element section is higher than the output voltage of the rectenna element section. The rectenna device according to claim 1, wherein: 3. A second switch element provided in parallel with the rectifier circuit, and a control means for controlling the first and second switch elements so as to be inverted and connected to each other. The rectenna device according to claim 1, wherein: