LT6326B - Simulator of solar light - Google Patents

Abstract

Designed a compact, efficient, a minimum amount of components (light emitting and additional optical elements) using the solar simulator for laboratory applications for example solar cell testing. The light rays used by semiconductor light-emitting diodes (LEDs). The simulator has a very low number of LEDs - used only 1-3 of the same type of single-color LEDs and 6 white LEDs (total - 19 LEDs). The required illuminance and the uniformity of the sample plane is achieved via arrangement of the LEDs by hexagonally ("honeycomb" type) lattice.

Description

Field of the Invention

The present invention relates to adjustable-spectrum solar simulators, and more particularly, to controlled solar-spectrum simulators using semiconductor LEDs.

State of the art

Solar simulators are luminaires that have a spectrum in the near ultraviolet, visible and near infrared areas that is close to the natural spectrum of the sun. Such luminaires are commonly used in laboratory testing of solar cells. They are also used in light therapy sessions to treat certain human disorders, or they can be used as elements of home comfort and so on. Solar simulators are also used for biomedical research, photobiology, testing of paints, other surface coatings or plastics and so on.

A solar simulator can be constructed from several types of light sources. Xenon fluorescent lamps are commonly used due to their relatively good match to the solar spectrum, and they are easy to filter for optimum exposure to solar simulator AAA according to the international standard IEC 60904-9 Ed. 2.0. However, in this case, a sophisticated optical focusing system is used for uniform illumination of the test surface.

Semiconductor light emitting diodes (LEDs) allow you to choose from a wide range of spectral bands. Although the first semiconductor light emitting diode (LED) was developed in 1962, it has only recently grown in power to become competitive with other light sources used. 1.5 W luminaires are already used to reproduce 90% of the solar simulator radiation according to the standards [Jang, S.H., and Shin, M.W .: 'Fabrication and thermal optimization of LED solar cell simulator', Curr. Appl. Phys., 2010, 10, pp. S537-S539.]. Combined sources of halogen lamps and luminaires are already able to achieve class B spectral compliance standards [Bliss, M., Betts, TR, and Gottschalg, R .: 'An LED-based photovoltaic measurement system with variable spectrum and flash speed', Solar Energy Materials & Solar Cells, 2009, 93, p. 825830.]. Because of the relatively large dimensions of the individual illuminating elements at the surface being studied, it is difficult to achieve a sufficiently compact arrangement to produce uniform illumination over all spectral ranges. With the help of fiber optics, the light sources can be moved further and the radiation arriving at the plane under investigation is mixed. In this way, the AM1.5G spectral assembly is achieved with 10% spatial unevenness in the 25 cm χ 50 cm study plane [Hamadani, B. H., Chua, K., Roller, J., Bennahmias, M. J., Campbell, B., Yoon, H. W., Dougherty , B., 'Towards realization of a large-area light-emitting diode-based solar simulator, Prog. Photovolt .: Res. Appl., 2011.21, p.p. 779-789],

In patent application no. US 13 / 373,780 discloses a control system for solar light spectrum lamps. By changing the power supply of the LEDs, the spectrum is controlled and adjusted as close to the Sun's spectrum as possible. It also describes the arrangement of the LEDs into individual square (2cm x 2cm) segments of 16 units and 6 or 12 different wavelengths, further alignment of the segments into a 40-unit array, and focusing cones attached to each segment. The specific alignment of the LEDs and the electronic control circuit are suitable for the use of small dimensions of individual illuminating components without the need for additional heat dissipation. This limits applications to more powerful sources.

In patent application no. US 13 / 533,790 is a sophisticated optical system for projecting a light source image into a plane of interest so as to obtain illumination from multiple positions. Such a projector creates uniformity of light intensity in the plane under investigation.

In patent application no. US 13 / 896,768 describes a matrix of geometrical parameters of small lamps for the most accurate reproduction of the solar spectrum. The sunlight simulator is made up of 23 different light fixtures and reproduces the sunlight spectrum quite well. The invention utilizes modular interconnection and perpendicular counter-mirrors on the sides of matrices, creating the illusion of an infinite area light source.

Pat. US8,315,848 B2 describes the control of the luminous flux of individual groups of luminaires with respect to illumination only over a small area of the plane under investigation. This produces a "scanning" simulator of the Sun. Applications of this simulator are limited to studies that can be performed on the plane under investigation in small segments.

International patent application no. PCT / JP2010 / 000512 discloses uniform illumination of the plane under investigation using remote light sources using light-diffusing prismatic optical components. Light enters the diffusing element through ducts with semi-transparent mirrors that allow different frequencies of radiation from different sources to be mixed

Spot light sources with several types of conical optical system as described in patent application no. US 13 / 980,326, or flat-form collimators of the same shape as described in US 13 / 759,796, are planarly aligned and are also referred to as solar light simulators.

In patent application no. US 12 / 874,600 describes a modular arrangement of individual light elements on a single cooling element for greater power. Together with the optical integrator, more homogeneous lighting is achieved. The test plane is equipped with an electrical measurement stand along with temperature control and computerized measurement and light source control.

When testing solar cells, part of the light from the cell is reflected back to the plane of the light source of the solar simulator, from which secondary reflection to the solar cell takes place. In this way, the effective illumination of the solar cell is higher than that of natural light and causes difficulties in assessing the performance of such a cell. For this purpose, a light-absorbing layer, as described in patent application no. US 13 / 390,101. It also describes the in-plane alignment of point sources (square or hexagonal) and the measurement method.

In patent application no. US 13 / 373,780 describes the use of arrays of different colors of light together with secondary optics - light mixing cones.

The closest analogue to our invention is disclosed in patent application no. US 13 / 980,326, which discloses an array of LEDs with secondary (reflectors) and tertiary (diffuse screen) optical elements. This application solves the problem of mixing light of different colors in the plane of the sample. This is achieved by the use of secondary and tertiary optical elements.

In the case of the nearest analogue, secondary or tertiary optical elements are used for all groups of luminaires, they require a large amount of space, require precise mechanical positioning and additional supporting structures.

In our proposed simulator, LEDs of sufficient power are used to provide sufficient overlap of radiation emitted by them, using as few secondary optical elements as possible. In the case of the proposed new simulator, additional reflectors are only used with the tri-color luminaires arranged in the outer ring of lights. The arrangement of each group of colored lights is done with respect to the central symmetry. Reflectors are used for only 3 out of 6 groups of LEDs, while the centered LEDs utilize overlapping fluxes without secondary optics.

Brief Description of the Invention

The object of the invention is to create a compact, high-performance, solar-simulator for laboratory applications, such as LEDs and additional optical elements, e.g. for solar cell testing. The created simulator is characterized by extremely low number of used LEDs - only 1-3 monochrome LEDs of different spectral ranges and 6 white LEDs are used. 19 LEDs in total, 5W or more each. The required energy coverage and its uniformity in the plane of the specimen are ensured by the arrangement of these lamps with a hexagonal (honeycomb) grid, optimized arrangement of the rings in the rings and reflectors in the outer ring of the lamps.

Brief description of the drawings

Fig. 1 is a spatial representation of the structure of a solar simulator.

Fig. Figure 2 is a top view of the construction of a solar simulator.

Fig. 3 is a graph of the overlap spectra of all sources in a solar simulator.

Fig. Figure 4 shows the position of the structure of the light sources with the cooler relative to the object to be illuminated.

Detailed Description of the Invention

Light sources (3) with soldered radiators (4) are mounted on the heat-conducting plate (1) with heat radiators (2). Light reflectors (5) are mounted on the group of light sources which form the outer hexagonal ring. This ring consists of three groups of white light (11) and a narrow spectrum with peaks at 940 ± 20 nm (10) and 740 ± 20 nm (9). The use of reflectors (5) allows to increase the energy illumination to the required plane in the sample plane for these groups of illuminators, partially compensates for the effect of a greater distance from the center, and allows the distribution of that energy illumination to be optimized. Other light sources (6, 7, 8) are without additional optical elements.

All light sources (6, 7, 8, 9, 10, 11) are arranged so that when their radiation is mixed in a test plane (12) containing the test object (13) and parallel to the plate (1), a class A spectral and Distribution of class A intensity over a plane (12) of area greater than 5x5 cm ² . The center-mounted luminaire (6) has a dominant spectral component in the blue light range with a maximum spectral intensity at 450 ± 20 nm. Symmetrically, three light sources (7) with a spectral component in the infrared spectrum with a maximum spectral intensity at 850 ± 20 nm, and three other light sources (8) with a spectral component in the red spectrum at maximum 660 ± 20 nm. Next, in the second group of illuminators (9, 10, 11) from the center, the other three light sources (9) are arranged, with the spectral component in the red spectral range with a maximum spectral intensity at 740 ± 20 nm and the other three light sources (10). ) with a spectral component in the infrared spectrum with a maximum spectral intensity at 940 ± 20 nm. In order to achieve the densest filling of the panel (1), the lights are aligned in the form of a hexagonal grid (honeycomb). The remaining six light sources (11) are arranged symmetrically in the outer perimeter. The latter light sources (1) are white light with a correlated color temperature of 5000 K to 6500 K and their spectral range combines the range of the other nearest light sources between 400 nm and 660 nm. The overlapping flows of all these sources produce the AM1.5G spectrum corresponding to IEC 60904-9 Ed. 2.0

The structure of the light sources (number in the drawing) with the cooler (2) is fixed so that the light flux is directed to the object (13) located at the central light source (6), 10-20 cm from the plate (1) or at another distance, depending on the required energy illumination and the required unevenness class. When the operating temperature of the luminaires has stabilized, an area of at least 5 cm ² is illuminated at a distance of 18 cm and illuminated according to the spectral A and the classes of A intensity and A stability. In order to ensure stable operation of the simulator, the cooling air flow (14) is additionally directed to the cooler (2).

Claims (5)

Definition of the invention 1. A solar simulator consisting of luminaires arranged on a heat-conducting surface, characterized in that it comprises nineteen luminaires (3, 6, 7, 8, 9, 10, 11) each having an individual power of at least 5W arranged in a hexagonic grid for two. hexagonal rings around the central luminaire (6). 2. A solar light simulator according to claim 1, comprising at least 5W of white light (11) and 450 ± 20 nm peak light (6) emitting light at intervals of 400 nm to 600 nm; at least 5W power 740 ± 20 nm (9) peak beams emitting light in the range 700 to 800 nm; and at least 5W of 940 ± 20 (10) nm peak luminous fluxes at 900 nm to 1100 nm. 3. Solar light simulator according to claim 2, characterized in that the outer array of rectangular hexagonal lamps is formed by at least 6 white luminaires (11) and other 6 luminaires, three (9) of which have a maximum emission spectrum in the range of 700 nm to 800 nm. and the remaining three (10) have a peak emission spectrum in the 900 nm to 1100 nm range and their light is concentrated using an individual reflector. 4 Solar light simulator according to one of claims 1 to 3, characterized in that one high wavelength blue light (6) of wavelength in the range 400-500 nm is mounted centrally with respect to other groups of lamps. 5. A solar simulator according to claim 4, wherein said rectangular hexagonal lamp (6) is provided with a plurality of lamps having a spectral width of up to several tens of nm at 600-700 nm and 800-900 nm.