JP2017169369A - Power transmission system, power reception device, power transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To receive transmitted light by a multijunction solar cell without providing a light source, corresponding to all absorption wavelengths of subcells constituting the multijunction solar cell, in a power transmission device, and to convert into electric energy.SOLUTION: A power transmission system 1 includes a power transmission device 2, a power reception device 3, and an optical transmission part 4. The power transmission device includes light sources 20-1 through 20-M capable of outputting laser light of first through M-th wavelengths. The power reception device includes a multijunction solar cell part 30, auxiliary light sources 31-(M+1) through 31-N capable of outputting the light of (M+1)-th through N-th wavelengths, an auxiliary optical transmission part 32, and a control section 33. A multijunction solar cell 300 includes first through N-th subcells 300-1 through 300-N, and when laser light of first through M-th wavelengths are irradiated simultaneously from the power transmission side, the auxiliary light sources controls to output the light of (M+1)-th through N-th wavelengths simultaneously.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a system, a power receiving device, and a method for power transmission, and more particularly to a system, a power receiving device, and a method for transmitting power by light using a multi-junction solar cell. is there.

  A system that transmits light output from a light source of a power transmission device to a power reception device, receives the transmitted light by a solar cell of the power reception device, and converts the received light energy into electric energy by the solar cell, thereby transmitting power. (Patent Documents 1 and 2, Non-Patent Documents 1 and 2).

JP-A-11-89120 JP 2008-245404 A

Kazuya Takeda, 1 other, "100m energy transmission experiment to the lunar ice exploration rover model using a semiconductor laser," Japan Aerospace Society Proceedings, 2003, Vol. 51, No. 594, pp.393-396 Takuaki Suzuki and three others, “Research Status of Laser-based Space Solar Utilization System at JAXA”, IEICE Technical Report SPS2009-01, 2009, pp.1-4

  Since sunlight covers a wide wavelength range, single-junction solar cells with a single band gap (absorption wavelength) have limited power generation efficiency. To improve this, multiple solar cells with different band gaps (absorption wavelengths) can be used. A multi-junction solar cell in which solar cell layers (subcells) are stacked has been developed. Since a multi-junction solar cell is usually made by stacking a plurality of subcells, the plurality of subcells are connected in series. Therefore, the minimum output current in each subcell is the output current of the multijunction solar cell. Ordinary multi-junction solar cells are adjusted so that the output in each subcell is substantially equal to the wavelength spectrum of sunlight. Therefore, for such a multi-junction solar cell, if all light having a wavelength corresponding to the absorption wavelength of each sub-cell is not irradiated simultaneously, a sub-cell having an output current of 0 is generated. Can not be taken out. For example, even if a single single-wavelength laser beam is irradiated, an output current is obtained from the subcell corresponding to that wavelength, but the output current from the other subcell is 0, so that electric energy is extracted as a result. I can't do that.

  Therefore, in order to improve the power transmission efficiency, when a multi-junction solar cell is adopted as a solar cell, it is necessary to prepare a light source corresponding to all the absorption wavelengths of the subcells constituting the multi-junction solar cell in the power transmission device. However, there is no light source suitable for power transmission for any of the absorption wavelengths of the plurality of subcells constituting the multi-junction solar cell, or a light source suitable for power transmission may be provided in the power transmission device. In some cases, it may be difficult to avoid providing a light source corresponding to all of the absorption wavelengths of the subcells constituting the multi-junction solar cell in the power transmission device.

  Therefore, the present invention transmits the light output from the light source of the power transmission device to the power reception device without providing the power transmission device with a light source corresponding to all of the absorption wavelengths of the subcells constituting the multijunction solar cell. One of the objects is to enable transmission of electric power by receiving light by a multi-junction solar cell of a power receiving device and converting the received light energy into electric energy by the multi-junction solar cell.

  One aspect of the present invention includes a power transmission device, a power reception device, and an optical transmission unit, and the power transmission device is capable of outputting laser beams having wavelengths of first to Mth (M is an integer of 1 or more), respectively. 1 to M-th power transmission light source unit, and the power receiving apparatus includes a multi-junction solar cell unit including at least one multi-junction solar cell, and M + 1 to N-th other than the first to M-th wavelengths. And M + 1 to Nth (N is an integer larger than M) auxiliary light source units capable of outputting light of wavelengths, an auxiliary light transmission unit, and a control unit. 1 to Nth subcells, wherein the first to Mth wavelengths correspond to the absorption wavelengths of the first to Mth subcells, respectively, and the M + 1st to Nth wavelengths are M + 1 to Nth. Corresponding to the absorption wavelengths of the subcells, the first to Mth power transmission light source units output The laser beams having the first to Mth wavelengths can be simultaneously irradiated to the multi-junction solar cell unit through the optical transmission unit, and the M + 1 to M + 1 to Nth auxiliary light source units output. The N-th wavelength light can be simultaneously irradiated to the multi-junction solar cell unit through the auxiliary light transmission unit, and the control unit outputs the first to M-th power transmission light source units. When the first to Mth wavelength laser beams are simultaneously irradiated on the multi-junction solar cell unit, the M + 1 to Nth auxiliary light source units output the M + 1 to Nth wavelength light simultaneously. An electric power transmission system that can be controlled is provided.

  The control unit may control the M + 1 to M + 1th output currents so that a minimum output current among the output currents from the first to Mth subcells and an output current from each of the M + 1 to Nth subcells are substantially equal. It is possible to generate a control signal for controlling the intensity of the light of the M + 1 to Nth wavelengths output from the N auxiliary light source units.

  M is an integer greater than or equal to 2, and the controller is configured to output a minimum output current from the output current from each of the first to Mth subcells and the output current from the first to Mth subcells. So that the intensities of the first to Mth wavelengths of light output from the first to Mth power transmission light source units can be respectively controlled.

  The power generated by the multi-junction solar cell unit can be configured to be supplied to at least one of the M + 1 to Nth auxiliary light source units.

  The power receiving device may be a probe.

  Another aspect of the present invention is a power receiving device used in a power transmission system, the multijunction solar cell unit including at least one multijunction solar cell, and the first to Mth (M is an integer of 1 or more). ) M + 1 to Nth (N is an integer greater than M) wavelength light other than the M + 1 to Nth auxiliary light source units, an auxiliary light transmission unit, and a control unit. The multi-junction solar cell includes first to Nth subcells, wherein the first to Mth wavelengths correspond to the absorption wavelengths of the first to Mth subcells, respectively, The Nth wavelength corresponds to the absorption wavelength of each of the (M + 1) th to (Nth) subcells, and the M + 1st to (Nth) wavelength light output from the (M + 1) th to Nth auxiliary light source units is the auxiliary light transmission. The multi-junction solar cell part can be irradiated simultaneously via the part, and the control When the multi-junction solar cell unit is simultaneously irradiated with the first to M-th laser beams from the power transmission side, the M + 1 to N-th auxiliary light source units have the M + 1 to N-th wavelengths. A power receiving device that can be controlled so as to simultaneously output the light is provided.

  The control unit may control the M + 1 to M + 1th output currents so that a minimum output current among the output currents from the first to Mth subcells and an output current from each of the M + 1 to Nth subcells are substantially equal. The intensities of the M + 1 to Nth wavelengths output from the N auxiliary light source units can be controlled.

  M is an integer greater than or equal to 2, and the controller is configured to output a minimum output current from the output current from each of the first to Mth subcells and the output current from the first to Mth subcells. So that the intensities of the first to Mth wavelengths of light output from the first to Mth power transmission light source units can be respectively controlled.

  The power generated by the multi-junction solar cell unit can be configured to be supplied to at least one of the M + 1 to Nth auxiliary light source units.

  The power receiving device may be a probe.

  Another aspect of the present invention is the first to Nth (N is an integer greater than M) including the first to Mth subcells respectively corresponding to the first to Mth (M is an integer of 1 or more) wavelengths. A multijunction solar cell unit including a multijunction solar cell including the subcells, and M + 1 to Nth auxiliary light source units that output light of M + 1 to Nth wavelengths other than the first to Mth wavelengths, respectively. Is transmitted to the multi-junction solar cell unit simultaneously with the first to Mth laser beams from the power transmission side, and the M + 1 to Nth The present invention provides a power transmission method for simultaneously irradiating the multi-junction solar cell part with light of the M + 1 to Nth wavelengths from an auxiliary light source part.

  The M + 1 to Nth auxiliary light source units so that the minimum output current among the output currents from the first to Mth subcells and the output current from each of the M + 1st to Nth subcells are substantially equal. Can control the intensities of the light of the M + 1 to Nth wavelengths output from the.

  M is an integer equal to or greater than 2, so that the output current from each of the first to Mth subcells is approximately equal to the minimum output current among the output currents from the first to Mth subcells. In addition, the intensity of the light of the first to Mth wavelengths can be controlled respectively.

  The power generated by the multi-junction solar cell unit may be configured to be supplied to at least one of the M + 1 to Nth auxiliary light source units.

  The multi-junction solar cell unit may be provided in a spacecraft.

  According to the power transmission system, the power receiving device, and the power transmission method according to the present invention, the light source corresponding to all the absorption wavelengths of the subcells constituting the multi-junction solar cell is output from the light source of the power transmission device without providing the power transmission device. Power can be transmitted by transmitting the transmitted light to the power receiving device, receiving the transmitted light by the multi-junction solar cell of the power receiving device, and converting the received light energy into electrical energy by the multi-junction solar cell. can do.

It is a figure showing composition of an electric power transmission system concerning one embodiment of the present invention. 1 is a circuit diagram of a power receiving device in a power transmission system according to an embodiment of the present invention.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of the power transmission system 1. FIG. 2 is a circuit diagram of the power receiving device 3 in the power transmission system 1. In FIG. 2, for the sake of simplicity, the multi-junction solar cell unit 30 is represented by one multi-junction solar cell 300.

  The power transmission system 1 includes a power transmission device 2, a power reception device 3 separate from the power transmission device 2, and a laser light transmission unit 4 that is an optical transmission unit.

  The power transmission device 2 includes first to Mth laser light source units 20-1 to 20-M that are first to Mth (M is an integer of 1 or more) power transmission light source units. Each of the first to Mth laser light source units 20-1 to 20-M includes a laser light source that outputs laser light having the first to Mth wavelengths and a laser light source driving circuit that drives the laser light source. Laser light having a wavelength of Mth (M is an integer of 1 or more) can be output. The first to Mth laser light source units 20-1 to 20-M can simultaneously output laser beams having the first to Mth wavelengths by a control unit (not shown). As the laser light source, any appropriate laser light source such as a fiber laser or a laser diode can be used. Moreover, other suitable arbitrary light sources, such as high-intensity LED, can be used as a light source of the light source part for power transmission, for example. Each component of the power transmission device 2 may be centrally arranged or distributed.

  The power receiving device 3 includes a multi-junction solar cell unit 30 including at least one multi-junction solar cell 300, M + 1 to N-th (N is an integer greater than M) auxiliary light source units 31- (M + 1) to 31-N. , An auxiliary light transmission unit 32, a control unit 33, an optical sensor unit 34, a power supply circuit unit 35, and an auxiliary power supply unit 36. Each component of the power receiving device 3 may be centrally arranged or may be distributed.

  The M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N drive auxiliary light sources and auxiliary light sources that respectively output light of M + 1 to Nth wavelengths other than the first to Mth wavelengths. An auxiliary light source driving circuit that outputs light of M + 1 to Nth wavelengths other than the first to Mth wavelengths. As the auxiliary light source, an appropriate arbitrary light source such as a laser light source or an LED light source can be used.

  The multi-junction solar cell 300 is formed by stacking a plurality of solar cell layers (subcells) having different band gaps (absorption wavelengths), and includes first to Nth subcells 300-1 to 300-N. For example, as a two-junction solar cell, there is an InGaP / GaAs two-junction solar cell in which an InGaP (absorption wavelength: 400 to 600 nm) subcell is stacked as a top layer and a GaAs (absorption wavelength: 700 to 900 nm) subcell is stacked as a bottom layer. As the three-junction solar cell, a subcell of InGaP (absorption wavelength 400 to 600 nm) is a top layer, a subcell of GaAs (absorption wavelength 700 to 900 nm) is a middle layer, and a subcell of InGaAs (absorption wavelength 900 to 1300 nm) is a bottom. There are InGaP / GaAs / InGaAs 3-junction solar cells stacked as layers. In addition, a 4-junction solar cell and a 5-junction solar cell are also realized. As described above, in a multi-junction solar cell, each sub-cell is connected in series. Therefore, in order to cause the multi-junction solar cell to generate power, all light having a wavelength corresponding to the absorption wavelength of each sub-cell is used. It is necessary to irradiate simultaneously, and the smallest output current in each subcell is the output current of the multijunction solar cell.

  The first to Mth wavelengths, which are the wavelengths of the laser beams output from the first to Mth laser light source units 20-1 to 20-M, respectively, are those of the first to Mth subcells 300-1 to 300-M. The M + 1 to Nth wavelengths corresponding to the absorption wavelengths and the wavelengths of light output from the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N are respectively M + 1 to Nth subcells. Each corresponds to an absorption wavelength of 300- (M + 1) to 300-N. For example, when using an InGaP / GaAs / InGaAs three-junction solar cell, it is necessary to prepare a light source that outputs light having a wavelength corresponding to each of absorption wavelengths 400 to 600 nm, 700 to 900 nm, and 900 to 1300 nm of each subcell. In this case, many laser light sources with a wavelength of about 1000 nm and about 800 nm are commercially available as long-distance transmission laser light sources. For example, (1) a laser light source with a wavelength of about 1000 nm as a laser light source of a power transmission device, Configuration using a light source such as a laser light source of 400 to 600 nm or 700 to 900 nm or an LED light source as an auxiliary light source of the device (in this case, M = 1, N = 3), (2) a wavelength of about 800 nm as a laser light source of the power transmission device (3) In this case, M = 1, N = 3, (3) Laser light source of power transmission device As a laser light source having a wavelength of about 1000 nm and 800 nm, a laser light source having a wavelength of 400 to 600 nm as an auxiliary light source of the power receiving device, and L Configuration using a light source such as D source three components (in this case M = 2, N = 3) are considered.

  The laser beam transmission unit 4 irradiates the multi-junction solar cell unit 30 of the power receiving device 3 with the laser beams output from the first to Mth laser light source units 20-1 to 20 -M of the power transmission device 2. It is a mechanism and consists of an optical system or the like. The optical system irradiates the multi-junction solar cell unit 30 with an optical system provided in the power transmission device 2 for laser beam direction control, waveform control, wavefront compensation, and the like, and a laser beam sent from the power transmission device 2, for example. Therefore, an optical system provided in the power receiving device 3 can be used. Further, the laser light transmission unit 4 may be constituted by an optical fiber. As described above, the first to Mth laser light source units 20-1 to 20-M can simultaneously output the laser beams having the first to Mth wavelengths by the control unit (not shown) of the power transmission device 2. The first to Mth laser light source units 20-1 to 20-M output the first to Mth wavelength laser beams simultaneously to the multi-junction solar cell unit 30 via the laser beam transmission unit 4. Is possible.

  The auxiliary light transmission unit 32 is a mechanism for irradiating the multi-junction solar cell unit 30 with light output from each of the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N. Become.

  The power supply circuit unit 35 is connected to the multi-junction solar cell unit 30, the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N, the control unit 33, the optical sensor unit 34, and the auxiliary power supply unit 36. . The electric power generated by the multi-junction solar cell unit 30 and the electric power from the auxiliary power supply unit 36 are supplied to the power supply circuit unit 35, and the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31- are supplied from the power supply circuit unit 35. N, power is supplied to the control unit 33, the optical sensor unit 34, and other loads (not shown).

  The optical sensor unit 34 is provided at an appropriate location near the light receiving surface of the multi-junction solar cell unit 30 or near the light receiving surface, and is sent via the laser light transmission unit 4 to the first to Mth laser light source units 20-. The intensity of the first to Mth wavelength laser beams output from 1 to 20-M and the M + 1 to Nth wavelengths output from the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N. The intensity of light can be measured.

  The auxiliary power supply unit 36 includes a secondary battery, and can be charged with electric power generated by the multi-junction solar cell unit 30. The auxiliary power supply unit 36 can be a combination of any appropriate power source other than the secondary battery or any other appropriate power source other than the secondary battery and the secondary battery.

  When the first to Mth laser light source units 20-1 to 20-M output the laser beams of the first to Mth wavelengths simultaneously to the multi-junction solar cell unit 30, the control unit 33 is configured to supply a power supply circuit. The power supply circuit unit 35 is controlled so that power is supplied from the unit 35 to the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N, and the (M + 1) th to Nth auxiliary light source units 31- (M + 1). ) To 31-N auxiliary light source drive circuits are driven, and the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N are simultaneously controlled to output light of M + 1 to Nth wavelengths. can do. Therefore, the M + 1 to Nth wavelength lights output from the (M + 1) th to Nth auxiliary light source units 31- (M + 1) to 31-N are transmitted to the multi-junction solar cell unit 30 via the auxiliary light transmission unit 32. Irradiation is possible at the same time. When such control is performed, light of a wavelength corresponding to all the subcells of the first to Nth subcells is irradiated, so that power generation is performed in the multijunction solar cell unit 30.

  Here, in order to cause the multi-junction solar cell to generate electric power as described above, it is necessary to simultaneously irradiate all light having a wavelength corresponding to the absorption wavelength of each subcell. Therefore, the total energy per unit time generated by the received laser beams having the first to Mth wavelengths is set in advance so as to be larger than the energy per unit time consumed by the power receiving device 3. The unit 33 initially controls the power supply circuit unit 35 so that power is supplied from the auxiliary power supply unit 36 to the M + 1st to Nth auxiliary light source units 31- (M + 1) to 31-N, whereby a multijunction is provided. When power generation is performed in the solar cell unit 30, the power supply circuit unit is configured so that power is then supplied from the multi-junction solar cell unit 30 to the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N. 35 is controlled.

  The power generated by the multi-junction solar cell unit 30 can be supplied to at least one of the M + 1 to Nth auxiliary light source units instead of being supplied to all of the M + 1 to Nth auxiliary light source units. The other auxiliary light source unit may be configured such that power can be supplied from the auxiliary power source unit 36, for example.

  In addition, the control unit 33 controls the M + 1 to 1st output current so that the minimum output current among the output currents from the 1st to Mth subcells is substantially equal to the output current from each of the M + 1st to Nth subcells. It is possible to control the intensities of light of M + 1 to Nth wavelengths output from the N auxiliary light source units.

Current i _j where subcell of the j occurs multijunction solar cell 300, the intensity of light of a wavelength of a j a I _j, a k _j when the photoelectric conversion coefficient of the sub-cells of the j,
i _j = k _j I _j (1)
It can be expressed as. The control unit 33 uses the intensity I _{1 to} I _{M of the first} to Mth wavelength laser beams output from the first to Mth laser light source units 20-1 to 20 -M measured by the optical sensor unit 34 and a formula. Based on (1), the minimum current i ₀ among the currents i _{1 to} i _M generated by the first to Mth subcells is obtained. And the control part 33 is intensity | strength I _{M + 1} -I of the light of the M + 1th-Nth wavelength which M + 1-Nth auxiliary light source part 31-M + 1-31-N which the optical sensor part 34 measured outputs. based on the _N and equation (1), and each of the current i _{M + 1} through i _N where subcell of the first M +. 1 to No. N is generated, the minimum current i ₀ of the current i ₁ through _M approximately equal As described above, the intensity of light of the M + 1 to Nth wavelengths output from the (M + 1) th to Nth auxiliary light source units 31- (M + 1) to 31-N can be controlled via each auxiliary light source driving circuit.

Instead of this, and each of the current i _{M + 1} through i _N where subcell of the first M +. 1 to No. N is generated, so that the minimum current i ₀ of the current i ₁ through i _M approximately equal, the M + 1 The intensity of light of M + 1 to Nth wavelengths output from the Nth auxiliary light source units 31- (M + 1) to 31-N may be controlled. That is, first, the control unit 33 outputs light of M + 1 to Nth wavelengths output from the M + 1st to Nth auxiliary light source units 31- (M + 1) to 31-N via each auxiliary light source driving circuit. strength, respectively, the minimum predetermined strength such that larger than the current i ₀ of one of the current i ₁ through i _M the current sub-cells of the first M + 1 N-th generated the subcell of the first to M occurs (For example, the maximum intensity that each of the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N can output). At this time, the output current of the multi-junction solar cell 300 is i ₀ . Next, the control unit 33 outputs light output from the auxiliary light source unit via the auxiliary light source driving circuit of one of the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N. Is reduced until the output current of the multi-junction solar cell 300 is not significantly lower. This operation is performed for each of the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N. According to this configuration, each of the currents i _{M + 1 to} i _N generated by the _{M +} 1th to _Nth subcells by measuring the output current of the multi-junction solar cell 300 without providing the optical sensor unit 34. When, as a minimum current i ₀ of the current i ₁ through i _M approximately equal, the first M +. 1 to the N-th auxiliary light source unit 31- (M + 1) ~31- N of the first M +. 1 to N-th output The intensity of light of a wavelength can be controlled.

As described above, since the minimum output current in each subcell is the output current of the multijunction solar cell, the current i generated in the entire multijunction solar cell 300 is:
i = min (k ₁ I ₁ , ..., k _M I _M , k _{M + 1} I _{M + 1} , ..., k _N I _N ) (2)
It can be expressed as. That is, of the currents i _{1 to} i _M generated by the first to Mth subcells by the first to Mth wavelength laser beams from the first to Mth laser light source units 20-1 to 20-M. While it is useless to irradiate each subcell with light having an intensity larger than the minimum current i _0, it is wasteful from the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N. When the currents i _{M + 1 to} i _N generated by the M + 1 to Nth subcells with light of the M + 1 to Nth wavelengths are less than i ₀ , the first to Mth laser light source units 20 − Energy transmitted from the 1st to Mth laser beams from 1 to 20-M is wasted. Therefore, by performing the control as described above, it is possible to avoid wasting light energy transmitted from the power transmission side and consuming wasted energy in the auxiliary light source unit.

Further, when M is 2 or more, the control unit 33 outputs the first to Mth wavelength laser beams output from the first to Mth laser light source units 20-1 to 20-M measured by the optical sensor unit 34. based on the intensity I ₁ ~I _M of formula (1), and each of the current i ₁ through i _M where subcell of the first to M occurs, minimum current i ₀ of the current i ₁ through i _M For controlling the intensity of the light of the first to Mth wavelengths output from the first to Mth laser light source units 20-1 to 20-M via each laser light source driving circuit. A control signal can be generated and transmitted to the power transmission device 2. By performing such control, it is possible to avoid further wasting energy in the laser light source unit. Instead of or in addition to performing such control, the first to Mth subcells are grasped in advance based on the characteristics of the first to Mth subcells and the characteristics of the laser beam transmission unit 4. as but each current i ₁ through i _M is approximately equal to occur, the intensity of the first to the laser beam of the wavelength of the M laser light source unit 20-1 to 20-M of the first to M outputs I Of course, _{1 to} I _M may be set.

  Then, operation | movement of the electric power transmission system of this embodiment is demonstrated.

  First, the first to Mth laser light source units 20-1 to 20-M of the power transmission device 2 simultaneously output laser beams having the first to Mth wavelengths by a control unit (not shown) of the power transmission device 2, The multi-junction solar cell unit 30 is irradiated simultaneously via the transmission unit 4. On the other hand, the control unit 33 of the power receiving device 3 controls the power supply circuit unit 35 so that power is supplied from the auxiliary power supply unit 36 to the M + 1st to Nth auxiliary light source units 31- (M + 1) to 31-N. The M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N are driven to drive the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N to M + 1 to M + 1. Control is performed so that light of the Nth wavelength is output simultaneously. As a result, when the multi-junction solar cell unit 30 is simultaneously irradiated with light of M + 1 to N-th wavelengths via the auxiliary light transmission unit 32 and power generation is performed in the multi-junction solar cell unit 30, The control unit 33 controls the power supply circuit unit 35 so that power is supplied from the multi-junction solar cell unit 30 to the M + 1st to Nth auxiliary light source units 31- (M + 1) to 31-N. The multi-junction solar cell unit 30 continues to generate power without requiring power supply from the unit 36.

  The timings at which the M + 1 to Nth wavelengths of light are simultaneously output from the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N are the first to Mth wavelength laser beams and the M + 1 to Nth wavelengths. If the multi-junction solar cell unit 30 is simultaneously irradiated with light of N wavelengths, the first to Mth lasers from the first to Mth laser light source units 20-1 to 20-M. It may be before or after the timing of simultaneously outputting light. The timings at which the M + 1 to Nth wavelengths of light are simultaneously output from the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N are the first to Mth laser light source units 20-1 to 20-. If it is simultaneously with the timing of simultaneously outputting laser beams having the first to Mth wavelengths from M, it is possible to avoid wasting energy.

The control unit 33 uses the intensity I _{1 to} I _{M of the first} to Mth wavelength laser beams output from the first to Mth laser light source units 20-1 to 20 -M measured by the optical sensor unit 34 and a formula. Based on (1), the minimum current i ₀ among the currents i _{1 to} i _M generated by the first to Mth subcells is obtained, and the M + 1 to Nth auxiliary light source units measured by the photosensor unit 34. 31- (M + 1) to 31-N is based on the first M +. 1 to the intensity of light of a wavelength of N I _{M +} 1 ~I _N and wherein outputting (1), the current sub-cells of the first M +. 1 to No. N are generated Each of i _{M + 1 to} i _N and the minimum current i ₀ among the currents i _{1 to} i _M are substantially equal to each other through the auxiliary light source driving circuits, and the (M + 1) th to Nth auxiliary light source units 31. You may control the intensity | strength of the light of the (M + 1) th-Nth wavelength which (M + 1) -31-N outputs.

Instead of this, and each of the current i _{M + 1} through i _N where subcell of the first M +. 1 to No. N is generated, so that the minimum current i ₀ of the current i ₁ through i _M approximately equal, the M + 1 The intensity of light of M + 1 to Nth wavelengths output from the Nth auxiliary light source units 31- (M + 1) to 31-N may be controlled. That is, first, the control unit 33 outputs light of M + 1 to Nth wavelengths output from the M + 1st to Nth auxiliary light source units 31- (M + 1) to 31-N via each auxiliary light source driving circuit. strength, respectively, the minimum predetermined strength such that larger than the current i ₀ of one of the current i ₁ through i _M the current sub-cells of the first M + 1 N-th generated the subcell of the first to M occurs (For example, the maximum intensity that each of the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N can output). At this time, the output current of the multi-junction solar cell 300 is i ₀ . Next, the control unit 33 outputs light output from the auxiliary light source unit via the auxiliary light source driving circuit of one of the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N. Is reduced until the output current of the multi-junction solar cell 300 is not significantly lower. This operation is performed for each of the M + 1 to Nth auxiliary light source units 31- (M + 1) to 31-N.

When M is 2 or more, the control unit 33 outputs the intensities of the first to Mth wavelength laser beams output from the first to Mth laser light source units 20-1 to 20-M measured by the optical sensor unit 34. based on the I ₁ ~I _M and formula (1), and each of the current i ₁ through i _M where subcell of the first to M occurs, minimum current i ₀ of the current i ₁ through _M approximately Control signals for controlling the intensities of the first to Mth wavelength lights output from the first to Mth laser light source units 20-1 to 20-M through the laser light source driving circuits so as to be equal. May be generated and transmitted to the power transmission device 2. Instead of or in addition to performing such control, the first to Mth subcells are grasped in advance based on the characteristics of the first to Mth subcells and the characteristics of the laser beam transmission unit 4. as but each current i ₁ through i _M is approximately equal to occur, the intensity of the first to the laser beam of the wavelength of the M laser light source unit 20-1 to 20-M of the first to M outputs I Of course, _{1 to} I _M may be set.

  When the above embodiment is applied to power transmission from the mother ship (lander) to the exploration rover in space exploration, that is, when the power transmission device 2 is the mother ship and the power receiving device 3 is the exploration rover, the following effects are obtained. . That is, currently, in space exploration, solar energy is converted into electric energy using a solar cell and used, but in the surface exploration of the moon and Mars, there are night and shaded areas. For example, when exploring the polar region of the moon, the hills have a relatively long sunshine period (the day lasts about half a year), whereas the region you want to explore (locations where volatile substances such as water ice exist) It is a short sunshine area such as the bottom. For this reason, nuclear energy is mainly used. However, nuclear energy is important to manage in terms of exposure and the cost is high. Therefore, if a mother ship equipped with a laser transmitter is landed in a place with good sunshine conditions and power can be sent from there to an exploration rover that explores a shaded area, exploration activities can be performed efficiently. The exploration rover is equipped with solar cells for daytime activities or activities in areas with sunshine. However, if this embodiment is applied, the exploration rover has a laser radio that is different from the solar cells. Without installing a photoelectric conversion device dedicated to power transmission, the solar cell mounted on the exploration rover can be used as a multi-junction solar cell with high power generation efficiency and also used for laser wireless power transmission. Moreover, since the configuration of the power supply system after the solar cell is exactly the same in the case of sunlight input and laser light input, the number of man-hours for ground testing can be reduced and the reliability can be improved.

  Although the present invention has been described above with reference to several embodiments for purposes of illustration, the present invention is not limited thereto and may be described in form and detail without departing from the scope and spirit of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made.

DESCRIPTION OF SYMBOLS 1 Electric power transmission system 2 Power transmission apparatus 20-1-20-M The 1st-Mth laser light source part 3 Power receiving apparatus 30 Multijunction solar cell part 300 Multijunction solar cell 300-1-300-N 1st-Nth Subcells 31- (M + 1) to 31-N M + 1 to Nth auxiliary light source units 32 Auxiliary light transmission unit 33 Control unit 34 Optical sensor unit 35 Power supply circuit unit 36 Auxiliary power supply unit 4 Laser light transmission unit

Claims (15)

A power transmission device, a power reception device, and an optical transmission unit;
The power transmission device includes first to Mth power transmission light source units capable of outputting laser beams having wavelengths of first to Mth (M is an integer of 1 or more), respectively.
The power receiving device is:
A multi-junction solar cell portion comprising at least one multi-junction solar cell;
M + 1 to Nth (N is an integer greater than M) auxiliary light source units capable of outputting light of M + 1 to Nth wavelengths other than the first to Mth wavelengths,
An auxiliary light transmission unit;
A control unit;
With
The multi-junction solar cell includes first to Nth subcells,
The first to Mth wavelengths correspond to the absorption wavelengths of the first to Mth subcells, respectively.
The M + 1 to Nth wavelengths correspond to the absorption wavelengths of the M + 1 to Nth subcells, respectively.
The first to Mth laser light wavelengths output from the first to Mth power transmission light source units can be simultaneously irradiated to the multi-junction solar cell unit via the optical transmission unit,
The M + 1 to Nth wavelengths of light output from the M + 1 to Nth auxiliary light source units can be simultaneously irradiated to the multi-junction solar cell unit via the auxiliary light transmission unit,
When the first to M-th laser light beams output from the first to M-th power transmission light source units are simultaneously irradiated to the multi-junction solar cell unit, the control unit has an M + 1 to N-th number. A power transmission system in which an auxiliary light source unit is controllable so as to simultaneously output light of the M + 1 to Nth wavelengths. The control unit may control the M + 1 to M + 1th output currents so that a minimum output current among the output currents from the first to Mth subcells and an output current from each of the M + 1 to Nth subcells are substantially equal. Intensities of light of the M + 1 to Nth wavelengths output from the N auxiliary light source units can be controlled, respectively.
The power transmission system according to claim 1. M is an integer greater than or equal to 2, and the controller is configured to output a minimum output current from the output current from each of the first to Mth subcells and the output current from the first to Mth subcells. Can generate control signals for controlling the intensities of the light beams having the first to Mth wavelengths output from the first to Mth power transmission light source units, respectively.
The power transmission system according to claim 1 or 2. The power generated by the multi-junction solar cell unit is configured to be supplied to at least one of the M + 1 to Nth auxiliary light source units.
The power transmission system according to any one of claims 1 to 3. The power receiving device is a probe.
The power transmission system according to any one of claims 1 to 4. A power receiving device used in a power transmission system,
A multi-junction solar cell portion comprising at least one multi-junction solar cell;
M + 1 to Nth auxiliary light source units capable of outputting light of wavelengths of M + 1 to Nth (N is an integer larger than M) other than the first to Mth (M is an integer of 1 or more) wavelengths, respectively. When,
An auxiliary light transmission unit;
A control unit;
With
The multi-junction solar cell includes first to Nth subcells,
The first to Mth wavelengths correspond to the absorption wavelengths of the first to Mth subcells, respectively.
The M + 1 to Nth wavelengths correspond to the absorption wavelengths of the M + 1 to Nth subcells, respectively.
The M + 1 to Nth wavelengths of light output from the M + 1 to Nth auxiliary light source units can be simultaneously irradiated to the multi-junction solar cell unit via the auxiliary light transmission unit,
When the first to Mth laser beams from the power transmission side are simultaneously irradiated onto the multi-junction solar cell unit, the control unit includes the M + 1 to Nth auxiliary light source units to the M + 1 to Nth. A power receiving device that can be controlled so as to simultaneously output light of a wavelength. The control unit may control the M + 1 to M + 1th output currents so that a minimum output current among the output currents from the first to Mth subcells and an output current from each of the M + 1 to Nth subcells are substantially equal. Intensities of light of the M + 1 to Nth wavelengths output from the N auxiliary light source units can be controlled, respectively.
The power receiving device according to claim 6. M is an integer greater than or equal to 2, and the controller is configured to output a minimum output current from the output current from each of the first to Mth subcells and the output current from the first to Mth subcells. Can generate control signals for controlling the intensities of the light beams having the first to Mth wavelengths output from the first to Mth power transmission light source units, respectively.
The power receiving device according to claim 6 or 7. The power generated by the multi-junction solar cell unit is configured to be supplied to at least one of the M + 1 to Nth auxiliary light source units.
The power receiving device according to any one of claims 6 to 8. The power receiving device is a probe.
The power receiving device according to any one of claims 6 to 9. A multi-junction solar cell including first to Nth subcells (N is an integer greater than M) including first to Mth subcells respectively corresponding to first to Mth wavelengths (M is an integer of 1 or more). The multi-junction solar cell unit including the cells and the M + 1 to Nth auxiliary light source units that output light of M + 1 to Nth wavelengths other than the first to Mth wavelengths, respectively, are used on the power reception side. A transmission method,
While simultaneously irradiating the multi-junction solar cell portion with the laser beams of the first to Mth wavelengths from the power transmission side, the M + 1 to Nth wavelength light from the M + 1 to Nth auxiliary light source portions, respectively. A power transmission method for simultaneously irradiating the multi-junction solar cell part. The M + 1 to Nth auxiliary light source units so that the minimum output current among the output currents from the first to Mth subcells and the output current from each of the M + 1st to Nth subcells are substantially equal. Respectively, controls the intensity of the light of the M + 1 to Nth wavelengths output by
The power transmission method according to claim 11. M is an integer equal to or greater than 2, so that the output current from each of the first to Mth subcells is approximately equal to the minimum output current among the output currents from the first to Mth subcells. And controlling the intensity of light of the first to Mth wavelengths, respectively.
The power transmission method according to claim 11 or 12. The power generated by the multi-junction solar cell unit is configured to be supplied to at least one of the M + 1 to Nth auxiliary light source units.
The power transmission method according to any one of claims 11 to 13. The multi-junction solar cell part is provided in a spacecraft,
The power transmission method according to any one of claims 11 to 14.

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