LED luminous principle for solid luminous, according to solid luminous physics principle, LED spectral almost all focus on the visible light range, so luminous efficiency as high as 90% above, so, the LED is known as the 21st century new light source, will soon become the incandescent lamp, fluorescent lamp, high strength gas discharge lamp after the fourth generation light source, is recognized as one of the ten leading technology, the 200W led Flood light source the new lighting light source will replace the traditional lighting light source, is driving a new industrial revolution - lighting revolution. According to the world financial crisis to deal with, the development and reform commission (NDRC) out of 4 trillion together with the local financial support is expected to have more than ten trillions of funds into the national transportation, support enterprises, improve the infrastructure construction. Recently the national ministry of science and technology in the national start "ten city all lamp" LED street lamp semiconductor lighting application engineering, in this strong east wind, always get government support of semiconductor lighting industry, is a great development opportunity.
1 system introduction
A complete set of LED solar street light system includes: 200W led Flood light source, controller, battery, solar cell module and light body. During the day, solar cell module converts light into electrical energy through the controller in the storage battery, and in the evening battery through the controller to light source power supply, make it into light energy, lighting road. The light body is mainly the system protection and the day of adornment effect, to ensure the normal operation of the cycle. The 200W led Flood light source, controller, battery is the key to street lamp system performance, the design must carry on the optimization design, reasonable configuration.
1) system matching problem
Now do solar lamps and lanterns manufacturers often too much pursuit of modelling design, and the most important system matching design to ignore, not after deep consideration, a simple calculation, and finally lead to appearance of a large number of lamps and lanterns, Some manufacturers to build their own products price advantage, sacrificing system stability, the practice is not desirable. Matching design is related to the system reliability and stability of the important factors to pay attention, basically should consider the following several aspects:
(1) solar cell power generation and load power consumption ratio reasonable.
(2) power consumption and battery capacity ratio for rainy days shall meet requirements and reasonable depth of discharge.
(3) the sun battery charging current and battery capacity matching reasonable.
(4) load discharge current and battery capacity matching reasonable.
2) LED street lamp technical features
The purpose of the road lighting for night travelers to provide a visual safe and reliable conditions, high brightness LED street lamp, its brightness must be in compliance with the existing road conditions, traffic safety must achieve brightness requirements. The luminous efficiency and luminous intensity can achieve the existing road lighting need brightness requirements. Road lighting since July 1st, 2007 implementation of the ministry of construction industry standard CJJ45-2006 "city road lighting design standard", the road lighting illumination requirements see table 1. In order to make the design tend to be more perfect, mainly for the following several points should be carefully considered: A kind of solar LED street lamp system matching design
(1) the choice of light source
Compared with conventional lighting, LED obvious advantages. LED belongs to low voltage power supply, insulation demand is not high, do not need to transformers, ballasts, starter and other accessories, obviously save investment; Simple structure, belong to solid light source, do not need to air, do not need glass shell, also does not exist gas seal, and impact resistance, resistance to shock, not easy and broken; LED is cold light source, controllability, fast response time, can be repeated frequently bright out, won't tired; Low energy consumption, long life, etc. LED street lamp intelligent is the core of the switching power supply design. Currently use a wide range of LED street lamp switch power supply general has rectifier filter circuit, adjusting circuit, sampling circuit, over current protection circuit and DC constant current output circuit. In the high power LED applications, the heat dissipation is another major aspect to consider, at present, the LED energy consumption of about 80% above is transformed into heat, and semiconductor devices is not high temperature resistant, heat to do bad, can cause very serious light failure, some serious half year may has been reduced by half in the street lamps, high-power LED is more a series parallel application, it is necessary to adopt the aluminum alloy many fin wind) to radiator.
(2) the choice of battery
Vrla battery application in China for ten years, since it has small volume, light weight, small self-discharge, long service life, less investment, easy installation, safe and reliable, easy to use, less maintenance over acid mist to the environment, no corrosion, no pollution and good characteristic, and can realize unattended and microcomputer monitoring modernization management way, So the photoelectric street light, photovoltaic engineering is widely used. But should correctly understand the meaning of "free maintenance", to ensure the safety and reliability of the system. In use process, the vrla battery maintenance need to build accurate charge and discharge system and implement, can we make the battery to achieve optimal performance and the longest service life. A large amount of research at home and abroad, according to the results of charging and discharging decisions about the battery using life, there are some battery is not so much use bad, rather than charging ways not damaged. Solar energy lamps and lanterns from the Angle of economy and reliability comprehensive consideration, general with annual average sunshine hours design calculation, and the actual configuration of lamps and lanterns, often is the controller control function set a working hours, such as 6 hours, eight hours, 1 o hours, etc., that would give the year time every day, every day power consumption is, but solar lamps and lanterns is to rely on the sun, and solar radiation along with different season is have very big difference, namely each lamps and lanterns (solar cell module must be) each season average daily power generation is not the same. In Texas the annual mean peak sunshine time is about 4.44 hours, spring: 4.43 hours, summer: 6.1 7 small day ", autumn: 4.47 hours, winter: 2.65 small day ". On an average day for power generation is and average peak sunshine real proportional to, so can spring and autumn power generation and power consumption basic reach a balance, the summer electricity rich; The winter of electricity. This summer, caused certain waste, and winter is seriously insufficient, very easy to cause the battery over discharge, affects the battery life. Out of self-discharge, system matching, factors such as cost is extremely not economical and practical. So the control load time can yet be regarded as a kind of solution, according to Texas peak sunshine hours available: summer average peak sunshine hours than the average peak sunshine hours than winter average peak sunshine time = 6.1. 'then. 65 = 7:5:3, then according to the annual peak sunshine time design work every day 1 o hours of solar lamps and lanterns 7:5:3 according to the ratio can reach the conclusion that summer the most allowed to work 14 hours, winter most allowed to work 6 hours (note: does not consider the influence of different season temperature). In view of this, in order to make the battery in winter not over discharge, adjustable load working time is less than or equal to 6 hours.
(3) controller design
Due to the solar battery components with the capacity of the weather conditions, sunshine time and change, very unstable, so the solar photovoltaic power generation system independent of battery charging and discharging control than ordinary application battery charging and discharging control some more complicated. Controller design is perfect, directly determine the solar street light system can run smoothly. Controller is the most important module is PWM dimming controller and constant current module. In the past a lot of investment to solar cell and LED. Very few people care about this two parts, so that in the present market condition of the controller are mostly not PWM dimming ability, and the constant flow module most are imported from abroad by the chip. In the solar street light usually is to use lead battery as energy storage unit, and lead battery output voltage from filled into full play, the voltage variation is close to 20%. So it caused by the LED current changes may more than four times more. Obviously this is not allowed. So be sure to put the current constant. In addition, the LED street lamp to add intelligent controller, LED street lamp have controlled, time control and temperature control, can according to ambient brightness automatic open-close street lamp, prevent the day bright light wasting; Can make the street lamp in the small hours to dawn time road traffic and pedestrian flow reduce automatically reduces the power supply current, the intensity of illumination control in a safe range, which have increased energy saving effect and prolong the service life of lamps and lanterns effect; When LED working temperature close to its limit critical temperature, automatic reduce its working current, protect both light source is not compromised, and ensure the safety of road illumination.
(4) other aspects
Due to the street lamp is cantilever structure, in the natural environment, by wind shear, upper air suspension, the safety of the structure is the first. So, try to simplify structure, designed to streamline, in order to reduce the wind resistance, increase the flow rate of the rain, and pay attention to lose weight, is to save a non-ferrous metal, 2 it is to reduce weight brought about by the stress problem, increase the safety of road lighting. At present the male known solar cell module, the packaging structure: glass a EVA a single solar cell a EVA - TPT membrane laminated packaging, put conductor, junction box, edge sealing tape and aluminum frame, the structure of the monomer battery connection is through the interconnection of the direct connection. Solar cell module just played a solar energy into electrical energy generation function, adornment effect is few, and the attention should be paid to wind dust and long-term outdoor conditions affect the climate. 2 tag China's total more than 100 million street lamp, as long as one of the 6 0 million light into solar street lamps, their annual save power is more than one of the three gorges hydropower plant capacity. If the future New Year 2 0 million street lamp all change to use solar street lamps, three years down another three gorges hydropower station. The energy saving effect is very considerable, and don't need to mobilize the forces to mobilize the whole power to build, and such launch of the local governments at all levels and all the power of the enterprise strength can be completed.