The Investigation And Design Of Optical System And Control System For LED Solar Simulators

Solar simulator is a kind of light source instrument which simulates the characteristics of solar light irradiation, and is widely used in the field of photovoltaic, aviation and so on. Solar simulator needs to simulate the radiation intensity, spectral matching degree and uniformity of the solar light, simultaneously. Since it is not affected by the weather and its radiation is stable, solar simulator is widely used as a light source.The solar simulator designed in this thesis is mainly used in the test of solar cells. The solar simulator takes the solid light source-light emitting diode(LED) instead of the traditional Xenon lamp as the light source of solar simulators. Solid light emitting diode has the advantages of low voltage driving, good stability, long service life tome, short response time, low carbon environmental protection, spectral diversity. With the continuous improvement of the power of a single chip, the use of solar simulators with solid light source becomes possible.In this thesis, the study is focused on the design of optical system and the control system of the solar simulator in order to match the national and international A-class standards under AM1.5 with different wavelength LEDs.In this thesis, the reason for selecting LED peak wavelength and structure is discussed in detail. In the national standard and international standard, the solar simulator spectrum is split in six parts and the percentage of light intensity in each of these parts is defined. According to the division band, eleven types of LEDs are selected. The structure of all LEDs is using four high power LED chip. In spectral matching progress, the spectral irradiance intensity of each LED in the effective irradiated area based on international standard was calculated. The drive current of all kinds of LEDs was adjusted to achieve the standard value.In the LED solar simulator optical system design process, LEDs arrangement is firstly designed and then the irradiation map on the effective area of eleven types of LEDs simulated is obtained through optical software Tracepro. Then the irradiance distribution is analyzed and the optimization method of adjusting the irradiance non-uniformity on the target area is summarized. From these, the partially driving method for controlling LED arrangement is obtained. The optical system of LED solar simulator contains two-time converging lights:the small package lens and the reflector made of high reflectance material. Through simulating by Tracepro, the best length of reflective cavity is 150mm. The control system adopts buck steady flow module as the driving power for LEDs, and control intensity of LED by the light control software. In the non-uniformity testing process, crystalline silicon solar cell is used as the detector to test the non-uniformity with dividing the 160mmX 160mm effective area into 100 test parts. The results show that the non-uniformity and temporal instability both reach level A standards and far superior than national and international standards. The non-uniformity in effective area is 1.61% and the temporary instability reaches 0.56%. In the end, we set up the test system of the volt ampere characteristic of solar cells, and write the software to test the various parameters of solar cells.