LED lighting has a landmark in the field of lighting. With the ever-increasing world demand for energy consumption, the storage of major energy resources in the contemporary world, such as oil, natural gas, and coal, is gradually decreasing. According to current mining speeds, oil and natural gas have only 40 years and 60 years of recoverable reserves, respectively. The search for the use of new and renewable energy sources and the development of energy-efficient technologies have received widespread attention worldwide.
Solar photovoltaic LED lighting is a typical application of new energy and energy-saving technologies. It converts solar energy in nature into electricity and provides it to LED light sources. Due to the low voltage, energy saving and long-term characteristics of LED light sources, the application of solar LED lighting systems will achieve high energy utilization efficiency, work reliability, and practical value. Therefore, the research on the control technology of solar photovoltaic power generation lighting system has received various attention.
LED lighting energy-saving principle
Solar photovoltaic LED lighting system consists of energy-efficient solar photovoltaic LED lighting system including solar battery pack, DC-DC converter, maximum power tracking MPPT control, battery storage and LED lighting control, LED light source And so on.
The working principle of the solar photovoltaic power generation lighting system is: in the period of sunlight, the solar battery group converts the collected solar energy into electric energy; under the control of the control system, the maximum power tracking (MPPT) method of the solar photovoltaic battery is adopted. Electrical energy is stored in the battery pack; when the LED lighting system needs power supply, it provides safe and efficient voltage and current to the LED lighting source. Make the LED lighting system work energy-efficiently and provide clean and environmentally-friendly green lighting for people's work and life.
Solar photovoltaic power generation is one of the main ways to use solar energy. The principle of solar photovoltaic cell power generation is the photovoltaic effect. For crystalline silicon solar cells, the typical value of the open circuit voltage is 0.5 0.6 V. The more electrons and hole pairs generated by light irradiation in the interface layer, the greater the current formed. The more light energy absorbed by the interface layer, the greater the same current. Currently used and researched solar cells are mainly silicon solar cells, compound semiconductor cells, and dye-sensitized solar cells. Silicon solar cells are currently the mainstream of solar photovoltaic cells. In silicon solar cells, the photoelectric conversion efficiency of monocrystalline silicon solar cells is the highest, the laboratory conversion efficiency is over 24%, and the efficiency of monocrystalline silicon solar cells produced on an industrial scale reaches 18%. the above. Thin-film solar cells have achieved great development in recent years. New solar cells such as polysilicon/crystalline silicon thin-film solar cells have also been industrialized, and the highest conversion efficiency has reached 16%. In recent years, research on compound semiconductor solar cells such as CIS, CIGS thin-film solar cells, and GaAs solar cells has also made practical progress. Dye-sensitized TiO solar cells have also achieved remarkable results.
There is a nonlinearity and variability between the output voltage and the current of the solar cell. There is a maximum power output point and a voltage-sum current corresponding to the maximum power point in a specific environment. When the environment changes, the output characteristics of solar cells also change. The characteristic curves of the output voltage and the output current of the solar cell are shown in Fig. 2. In order to obtain as much electric energy as possible from the solar cell, the maximum power tracking problem of the solar cell is proposed. The most common methods for maximum power point tracking control include constant voltage tracking, perturbation observation, conductivity increment, fuzzy logic control, and load current/voltage maximum. . According to the volt-ampere characteristic of LED, in the forward conduction area of ​​LE D, the slight voltage fluctuation will cause the great change of the electric current, so adopt constant current to drive is the scheme that should choose.
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