Power receiving system

Abstract

To provide a power reception system increased in energy conversion efficiency.SOLUTION: The power reception system according to the present disclosure comprises: a power conversion device that receives an electromagnetic wave transmitted from a space and converts it into power; a heat energy conversion device that is installed near the power conversion device to convert heat energy generated in the power conversion device; and a control unit that controls an operation of the heat energy conversion device on the basis of an energy intensity distribution of the electromagnetic wave.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power receiving system. [Background technology]

[0002] As one type of renewable energy, a space solar power satellite / station / system (SSPS or SPS) has been proposed, which converts solar energy in space into electrical energy using solar panels mounted on a satellite or the like, and transmits the electrical energy to the ground using electromagnetic waves such as microwaves or laser light (see, for example, Patent Documents 1 and 2). Compared to solar power generation on the ground, space solar power generation systems have the advantages of being unaffected by weather, being able to generate power day or night, and having a high solar light density, and are therefore attracting attention. For space solar power generation systems, various technologies have been proposed to efficiently transmit the power generated in space to the ground.

[0003] For example, Patent Document 1 discloses a technology for a space solar power generation system in which a satellite equipped with a solar cell that converts sunlight into electrical energy transmits microwaves based on the generated power to a ground antenna, which then converts the microwaves into electricity, and the system includes a group of multiple power generation satellites, with the transmitting antennas of the group of multiple power generation satellites serving as element antennas forming an array antenna.Patent Document 2 discloses a technology for generating electricity using leakage energy from a laser optical system, in which a reflector is actively made transmissive, a solar cell is placed on the back side of the reflector, and energy from the transmitted laser light is used to generate electricity.

[0004] However, conventional space solar power generation systems still have room for improvement in terms of energy conversion efficiency. In particular, the reality is that energy that is not converted into electric power in the receiving antenna and power conversion device is wasted heat and is not effectively utilized. Neither Patent Document 1 nor Patent Document 2 proposes a technology for effectively utilizing such waste heat from the receiving section to improve energy conversion efficiency. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3584925 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-153565 Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides a power receiving system that effectively utilizes waste heat on the ground to improve energy conversion efficiency. [Means for solving the problem]

[0007] In order to solve the above problems, the power receiving system according to the present disclosure is characterized by including a power conversion device that receives electromagnetic waves transmitted from outer space and converts them into electric power, a thermal energy conversion device that is arranged near the power conversion device and converts thermal energy generated by the power conversion device, and a control unit that controls the operation of the thermal energy conversion device based on the energy intensity distribution of the electromagnetic waves. [Effects of the Invention]

[0008] According to the power receiving system according to the present disclosure, it is possible to provide a power receiving system that effectively utilizes waste heat on the ground to improve energy conversion efficiency. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a schematic configuration of a space solar power generation system (power receiving system) according to a first embodiment. [Figure 2] 1 is a schematic diagram illustrating a schematic configuration of a space solar power generation system (power receiving system) according to a first embodiment. [Figure 3]FIG. 2 is a schematic diagram illustrating in more detail the configurations of a thermal energy converter 400 and a control unit 500 of the space solar power generation system (power receiving system) according to the first embodiment. [Figure 4] FIG. 10 is a schematic diagram illustrating a schematic configuration of a space solar power generation system (power receiving system) according to a second embodiment. [Figure 5] FIG. 10 is a schematic diagram illustrating a schematic configuration of a space solar power generation system (power receiving system) according to a third embodiment. [Figure 6] 10 is a graph illustrating the operation of the space solar power generation system (power receiving system) according to the third embodiment. [Figure 7] FIG. 10 is a schematic diagram illustrating a schematic configuration of a space solar power generation system (power receiving system) according to a fourth embodiment. [Figure 8] 1 shows an example of microwave energy intensity distribution. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may be designated by the same numerals. Note that the accompanying drawings show embodiments and implementation examples according to the principles of the present disclosure, but these are for understanding the present disclosure and are not to be used to interpret the present disclosure in a limiting manner. The descriptions in this specification are merely typical examples and are not intended to limit the scope or application of the present disclosure in any way.

[0011] Although the present embodiment has been described in sufficient detail to enable those skilled in the art to implement the present disclosure, it should be understood that other implementations and forms are possible, and that changes in configuration and structure and substitutions of various elements are possible without departing from the scope and spirit of the technical ideas of the present disclosure. Therefore, the following description should not be interpreted as being limited thereto.

[0012] [First embodiment] A schematic configuration of a space solar power generation system (power receiving system) according to a first embodiment will be described with reference to Figures 1 and 2. Figure 1 shows the overall configuration of the space solar power generation system, and Figure 2 is a block diagram showing a receiving antenna 200, a power converter 300, and a thermal energy converter 400. As shown in Figure 1, this space solar power generation system includes an artificial satellite 100, a receiving antenna 200, a power converter 300, a thermal energy converter 400, and a control unit 500, and is configured to supply generated power to a power grid (load) 600.

[0013] As an example, the artificial satellite 100 is a geostationary satellite that flies in a geostationary orbit (approximately 36,000 km above the equator) and is equipped with solar panels (e.g., approximately 2.5 km x 2.5 km) that convert sunlight into electricity. The artificial satellite 100 is configured to convert the electricity from the solar panels into microwaves (electromagnetic waves) with a frequency of, for example, 2.45 GHz (wavelength λ = 12.2 cm) or 5.8 GHz (wavelength λ = 5.17 cm), and emit the microwaves from a transmitting antenna toward the ground with, for example, an energy pointing accuracy of approximately 1 urad. Specifically, although not shown, the artificial satellite 100 is equipped with a frequency converter that converts DC power generated by the solar panels into AC power equivalent to the microwave frequency, a microwave controller that controls the amplitude, frequency, and phase of the microwaves, and a transmitting antenna.

[0014] The receiving antenna 200 is placed on the ground and is composed of a number of dipole antennas arranged in an array over an area of, for example, 3 km x 3 km. Each dipole antenna may have, for example, a horizontal conductor having a length of about half the wavelength λ of the microwave (approximately 6 cm for 2.45 GHz) and a vertical conductor having a length of about 1 / 4 the wavelength λ (approximately 3 cm for 2.45 GHz). Although a dipole antenna is described here, a patch antenna may also be used instead.

[0015] The power converter 300 is configured by a combination of, for example, a band-pass filter, a rectifier circuit, a low-pass filter, etc., and converts microwaves received by the receiving antenna 200 into, for example, commercial power. When converting the energy of the received microwaves into electrical energy, conversion loss occurs in electrical circuits, including a rectifier circuit having a diode, and heat is generated. The thermal energy converter 400 is disposed near the power converter 300 and has the function of converting the exhaust heat generated by the power converter 300 into other energy (heat, electricity). As will be described later, the thermal energy converter 400 is configured to be able to change its operation in accordance with the energy intensity distribution of the microwaves from the satellite 100. The control unit 500 is configured to acquire information on this energy intensity distribution and control the operation of the thermal energy converter 400.

[0016] 3 is a schematic diagram showing the structure of the space solar power generation system of the first embodiment in more detail. As an example, the thermal energy conversion device 400 is configured so that a heat conductive medium (e.g., water) passes near the power conversion device 300, and the heat conductive medium absorbs the exhaust heat generated from the power conversion device 300, thereby converting the heat into electric power. Specifically, as an example, the thermal energy conversion device 400 may be configured with a heat conductive medium flow path 401, a valve 402, a turbine generator 403, and a condenser 404. The heat conductive medium flow path 401 and the valve 402 together constitute a heat conductive medium flow mechanism that causes the heat conductive medium to flow.

[0017] The heat conduction medium flow paths 401 are arranged at a predetermined pitch near the power conversion device 300, and allow a heat conduction medium (such as water) to flow therethrough. The valves 402 are valves for adjusting the flow rate of the heat conduction medium flowing through the heat conduction medium flow paths 401, and are controlled by the control unit 500. The heat conduction medium that has passed through the heat conduction medium flow paths 401 and absorbed heat is sent to the turbine generator 403, causing the turbine generator 403 to rotate and generate electricity. The condenser 404 is configured to cool the heat conduction medium discharged from the turbine generator 403 and return it to the heat conduction medium flow path 401. Note that the turbine generator 403 is an example of a generator that generates electricity based on the thermal energy held in the heat conduction medium, and is not limited to this.

[0018] As described above, the thermal energy conversion device 400 is configured to be able to change its operation in accordance with the energy intensity distribution of the microwaves from the artificial satellite 100. Specifically, the flow rate of the heat conduction medium flowing through each of the plurality of heat conduction medium flow paths 401 can be changed by controlling the valves 402 in accordance with the energy intensity distribution of the microwaves.

[0019] The energy intensity distribution of microwaves transmitted from the satellite 100 is not uniform. It may have a nearly Gaussian distribution as shown in FIG. 8(a) or a Dolph-Chebyshev array distribution as shown in FIG. 8(b). It may also have a distribution with a central main distribution and side lobes or grating lobes around the periphery as shown in FIG. 8(c), or it may have a trapezoidal pattern as shown in FIG. 8(d). Even with the same Gaussian distribution, the distribution shape may change due to weather conditions or other radio wave interference. When microwaves have such a distribution, the power conversion device 300 may have areas that generate a large amount of heat locally depending on the distribution. Such localized heat generation may degrade the performance of the power conversion device 300 and increase the heat emitted by the power conversion device 300, reducing its energy conversion efficiency.

[0020] Therefore, as described above, the control unit 500 of this embodiment controls the operation of the thermal energy converter 400 (specifically, the flow rate of the heat conduction medium flowing through the heat conduction medium flow path 401) in accordance with the energy intensity distribution of the microwave.

[0021] Various methods can be used to measure the microwave energy intensity distribution. As an example, as shown in FIG. 3 , a temperature distribution calculation unit 520 measures the temperature distribution in the area near the power converter 300 based on the detection outputs of multiple temperature sensors 510 arranged near the power converter 300, and estimates the microwave energy intensity distribution from this temperature distribution. The control unit 500 can change the flow rate of the heat conductive medium flowing through the heat conductive medium flow path 401 according to the calculated temperature distribution. By flowing more heat conductive medium in high-temperature areas, the waste heat generated by the power converter 300 can be efficiently converted into electrical energy, thereby improving the overall energy conversion efficiency. This also suppresses localized heat generation in the power converter 300, thereby preventing circuit failure and degradation and improving the performance of the power converter 300. Note that in the illustrated example, multiple temperature sensors 510 are arranged near the surface of the power converter 300. However, this is not limited to this. For example, a thermographic camera capturing images of the surface of the power converter 300 can also be used.

[0022] 3, a combining circuit 405 can be provided that combines the generated power output by the thermal energy conversion device 400 and the generated power output by the power conversion device 300. The combined power output by the combining circuit 405 is obtained by combining not only the power generated by the power conversion device 300 but also the power obtained by converting the exhaust heat emitted by the power conversion device 300.

[0023] As described above, according to the space solar power generation system of the first embodiment, the exhaust heat of the power conversion device 300 is converted into other energy such as electrical energy by the thermal energy conversion device 400 and utilized, making it possible to provide a space solar power generation system with higher energy conversion efficiency than conventional systems.

[0024] [Second embodiment] Next, a space solar power generation system (power receiving system) according to a second embodiment will be described with reference to Fig. 4. The overall configuration of the system is similar to that of the first embodiment (Fig. 1), so a duplicated description will be omitted. Fig. 4 is a schematic diagram that particularly explains the parts that are different from the first embodiment, and the configuration and operation of the parts that are not shown are similar to those of the first embodiment.

[0025] In the second embodiment, the position of the heat conductive medium flow path 401 can be controlled to change the operation of the thermal energy converter 400 in accordance with the energy intensity distribution of the microwave. Specifically, as an example, the heat conductive medium flow path 401 is placed on a movable table 406 near (for example, below) the power converter 300, and the position of the movable table 406 can be controlled in accordance with a control signal from the control unit 500. The movable table 406 may be an autonomous vehicle that can move in any direction on the ground surface in response to a control signal from the control unit 500, as shown in FIG. 4, or may be a movable table that can move in only one or two directions along a movable rail (not shown).

[0026] In the second embodiment, the control unit 500 can control the position of the moving table 406 according to the calculation result of the temperature distribution by the temperature sensor 510. This allows the heat conductive medium flow path 401 to move to the position of the power converter 300 where a large amount of heat is generated, thereby suppressing localized heat generation. Therefore, the second embodiment can also achieve the same effects as the first embodiment.

[0027] [Third embodiment] Next, a space solar power generation system (power receiving system) according to a third embodiment will be described with reference to Fig. 5. The overall configuration of the system is similar to that of the first embodiment (Fig. 1), so a duplicated description will be omitted. The overall configuration of the system of this third embodiment is similar to that of the first embodiment (Fig. 1), so a duplicated description will be omitted. Fig. 5 is a schematic diagram that particularly explains the parts that are different from the first embodiment, and the configuration and operation of the parts that are not shown are the same as those of the first embodiment.

[0028] The third embodiment differs from the previous embodiments in the configuration for measuring the temperature distribution of the power conversion device 300. Specifically, the system of the third embodiment not only has a temperature sensor 510 disposed on the front side of the power conversion device 300 (the side where the receiving antenna 200 is disposed), but also has a temperature sensor 530 disposed on the rear side of the power conversion device 300, for example, near the ground. In this way, the space solar power generation system of this embodiment is configured to acquire data on the temperature distribution of two different regions and data on the temperature difference between the two regions, and to perform control according to this temperature difference.

[0029] As shown in FIG. 6 , the temperature distributions (T1, T2) of both the power converters 300 are calculated by the temperature distribution calculation units 520A and 520B, and the temperature difference distribution, which is the difference between the two temperature distributions, is calculated by the temperature difference distribution calculation unit 540. The control unit 500 acquires information on the temperature distribution of the power converter 300 and, ultimately, the microwave energy intensity distribution according to the calculation results of the temperature distribution calculation units 520A and 520B and / or the temperature difference distribution calculation unit 540, and can control the operation of the thermal energy conversion device 400. Specifically, the control unit 500 controls the thermal energy conversion device 400 so that more heat conduction medium flows in the region where the difference between the temperature distributions T1 and T2 is large. This makes it possible to suppress localized heat generation in the power conversion device 300. According to the third embodiment, by knowing not only the temperature distribution of the power converter 300 but also the temperature difference distribution at each portion, it is possible to perform more precise control of the thermal energy conversion device 400 and further improve the overall energy conversion efficiency. Although the above description has been given of an example in which the temperature sensor 530 is formed on the ground surface, the present invention is not limited to this, and it is sufficient that the temperature sensor 530 is positioned so as to be able to measure the temperature distribution at a position different from that of the temperature sensor 510.

[0030] [Fourth embodiment] Next, a space solar power generation system (power receiving system) according to a fourth embodiment will be described with reference to Fig. 7. The overall configuration of the system is similar to that of the first embodiment (Fig. 1), so a duplicated description will be omitted. The overall configuration of the system of this fourth embodiment is similar to that of the first embodiment (Fig. 1), so a duplicated description will be omitted. Fig. 7 is a schematic diagram that particularly explains the parts that are different from the first embodiment, and the configuration and operation of the parts that are not shown are the same as those of the first embodiment.

[0031] In this fourth embodiment, the thermal energy converter 400 is composed of a thermoelectric conversion element array 450 and a diffusion plate 460. The thermoelectric conversion element array 450 converts thermal energy into electrical energy using thermoelectric conversion elements rather than heat exchange using a thermally conductive medium, which is different from the previous embodiments. The thermoelectric conversion element array 450 is composed of an array of multiple thermoelectric conversion elements formed by bonding different types of semiconductors or metals. In the example shown in FIG. 7, the thermoelectric conversion element array 450 includes a first array 450A arranged near the center of the thermal energy converter 400 and a concentric, doughnut-shaped array 450B arranged at intervals around the first array 450A. However, this is merely an example and is not limiting. For example, the thermoelectric conversion element array 450 does not need to be concentric as shown in FIG. 7, but may be divided into multiple regions arranged in a grid pattern.

[0032] The diffusion plate 460 is disposed around the thermoelectric conversion element array 450 and has the function of diffusing the microwaves and changing the energy intensity distribution of the microwaves.

[0033] The control unit 500 controls the ON / OFF of the thermoelectric conversion elements in the thermoelectric conversion element array 450 using the drive circuit 550 in accordance with the calculation result of the temperature distribution calculation unit 510. This controls the operation of the thermal energy conversion device 400 in accordance with the energy intensity distribution of the microwave, thereby suppressing localized heat generation and improving the energy conversion efficiency of the system.

[0034] The output voltage (thermoelectric power) generated by a thermoelectric element can be expressed, for example, as V = S × ΔT (V is the output voltage, ΔT is the temperature difference, and S is the Seebeck coefficient (temperature dependent)). Thermoelectric elements exhibit improved performance when the Seebeck coefficient is large. This condition is realized when the temperature is high. Therefore, when the temperature of the power receiving device is high, the conversion efficiency (proportional to S) improves, and the temperature difference (ΔT) with the low-temperature side (ground surface) increases, resulting in a larger output voltage V. Therefore, in the fourth embodiment, the thermoelectric elements in the area where the temperature difference ΔT is large are turned on, and those in the area where it is small are turned off, thereby improving the thermoelectric conversion efficiency. Note that instead of or in addition to the control by the drive circuit 550, the positions of the thermoelectric element array 450 and the diffuser plate 460 themselves may be controlled by the moving table 406 as in the second embodiment. (others)

[0035] Although various embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present disclosure, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0036] For example, in the above embodiments, a thermoelectric converter that converts thermal energy into electrical energy has been described as an example of a thermal energy conversion device. However, this is not limited to this. It is also possible to use a thermo-thermal converter that converts thermal energy into other types of thermal energy or a device that converts thermal energy into mechanical energy. Specifically, in addition to the turbine generator and thermoelectric converter described above, the thermal energy conversion device can also be a gas turbine, a gas engine, a diesel engine, a fuel cell, a heat converter, or a waste heat absorption refrigerator. For example, thermal energy can be transferred to a medium such as pentane with a low boiling point, and the medium vapor can drive a turbine to generate electricity. A binary generator can also be used as a power generation system using a low boiling point medium. Furthermore, a thermoacoustic generator that converts heat into sound waves or vibrations to generate electricity can also be used. Thermoacoustic generators can generate electricity even at low temperatures of around 100 to 300 degrees Celsius, making them effective for the application of the present invention. Even when a thermo-thermal conversion device is used, the operation of the thermo-thermal conversion device can be controlled based on the microwave energy intensity distribution, as in the above embodiments, to achieve the same effects as those of a thermoelectric conversion device. The thermoelectric conversion device is not limited to a specific type, and various types can be used, such as those that apply the Seebeck effect or the spin Seebeck effect. Alternatively, a device that performs thermomagnetic power generation using the Nernst effect or the spin Nernst effect may be used.

[0037] In the above example, the control unit 500 is explained as estimating the energy intensity distribution of the microwave mainly according to the temperature distribution in the vicinity of the power converter 300 and controlling the operation of the thermal energy converter 400, but this is not limited thereto, and it is also possible to measure the energy intensity distribution of the microwave by measuring the intensity itself at each point of the microwave. Furthermore, the control unit 500 can estimate the energy intensity distribution of the microwave to be transmitted by acquiring control information of the frequency conversion circuit etc. of the artificial satellite 100. [Explanation of symbols]

[0038] 100...artificial satellite, 200...receiving antenna, 300...power conversion device, 400...thermal energy conversion device, 401...heat conduction medium flow path, 402...valve, 403...turbine generator, 404...condenser, 405...combining circuit, 406...moving table, 450...thermoelectric conversion element array, 450A...first array, 450B...array, 460...diffusion plate, 500...control unit, 510, 530...temperature sensor, 520, 520A, 520B...temperature distribution calculation unit, 540...temperature difference distribution calculation unit, 550...drive circuit, 600...power grid (load).

Claims

1. a power conversion device that receives electromagnetic waves transmitted from outer space and converts them into electric power; a thermal energy converter disposed near the power converter and configured to convert thermal energy generated by the power converter; a control unit that controls the operation of the thermal energy conversion device based on the energy intensity distribution of the electromagnetic wave; A power receiving system comprising:

2. a temperature distribution calculation unit that calculates a temperature distribution in the vicinity of the power conversion device, The power receiving system according to claim 1 , wherein the control unit estimates an energy intensity distribution of the electromagnetic wave in accordance with the temperature distribution and controls an operation of the thermal energy conversion device.

3. 3. The power receiving system according to claim 2, wherein the temperature distribution calculation unit controls the operation of the thermal energy conversion device according to a temperature distribution of a first region near the power conversion device and a temperature distribution of a second region near the power conversion device and different from the first region.

4. the thermal energy converter is a thermoelectric converter that converts thermal energy into electrical energy, The power receiving system according to claim 1 , further comprising a combining circuit that combines the electric power generated by the power converter and the electric power generated by the thermoelectric converter.

5. The thermal energy conversion device includes a heat conduction medium flow mechanism for flowing a heat conduction medium near the power conversion device, and a generator driven by the thermal energy of the heat conduction medium. Equipped with The power receiving system according to claim 1 , wherein the control unit controls the flow of the heat conducting medium in the heat conducting medium flow mechanism based on the energy intensity distribution.

6. The thermal energy conversion device includes a heat conduction medium flow mechanism for flowing a heat conduction medium near the power conversion device, and a generator driven by the thermal energy of the heat conduction medium. Equipped with The power receiving system according to claim 1 , wherein the control unit controls an arrangement position of the heat conducting medium flow mechanism based on the energy intensity distribution.

7. the thermal energy conversion device includes a thermoelectric conversion element array formed by arranging thermoelectric conversion elements, The power receiving system according to claim 1 , wherein the control unit controls an operation of the thermoelectric conversion element based on the energy intensity distribution.

8. The thermal energy conversion device includes the thermoelectric conversion element array, and a diffusion plate that is disposed around the thermoelectric conversion elements and diffuses the electromagnetic waves. The power receiving system according to claim 7 , comprising:

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