太陽(yáng)能LED路燈

1、advancements in solar based led street lightnupur 1 neha 1 sangya gugri 1 srishti mishra 1 gulshan kr. dubey 2ug student, dept. of eie, galgotias college of engineering & technology, uttar pradesh india 1associate professor, dept. of eie, galgotias college of engineering & technology, uttar pradesh,

2、 india 2abstract: we are in the time where energy conservation & use of renewable resources has become a necessity. thus requirement of methods which are not only highly efficient but also low in energy consumption has greatly increased to keep a check on pollution factor. keeping this in mind this

3、paper focuses on solar based led street light that uses automatic intensity controller with a solar tracker. this type of led street light not only adjust itself according to the varying darkness but also keeps a track on overcharging, deep discharging, automatic restoration of charging ,protecting

4、the battery from the over/under voltage. it comprised of solar cell and electric energy stored from battery. the led street lamp is lit at night automatically and changed into pulsed lighting in low power after the setting time and then turns off in daytime. since only 20% of the total suns energy f

5、alls on earth and also the trajectory of sun keeps changing thus a solar tracker is used so as to track maximum suns energy.keywords:solar panel, charge controller, intensity regulator, solar tracker.i.introductionthesurface of the sun has a temperature of about 5,800 kelvin (about 5,500 degrees cel

6、sius, or about 10,000 degrees fahrenheit),as per the say of nasa, at that temperature, most of the energy the sun radiates is visible and near- infrared light. at earths average distance from the sun (about 150 million kilometres), the average intensity of solar energy reaching the top of the atmosp

7、here directly facing the sun is about 1,360 watts per square meter, according to measurements made by the most recent nasa satellite missions. this amount of power is known as the total solar irradiance. (before scientists discovered that it varies by a small amount during the sunspot cycle, total s

8、olar irradiance was sometimes called “the solar constant.” averaged over the entire planet, the amount of sunlight arriving at the top of earths atmosphere is only one-fourth of the total solar irradiance, or approximately 340 watts per square meter.ii. solar trackersolar tracking system1 is the mos

9、t appropriate technology to enhance the efficiency of the solar cells by tracking the sun. a microcontroller based design methodology of an automatic solar tracker is presented in thispaper. light dependent resistors are used as the sensors of the solar tracker. the sun is the prime source of energy

10、, directly or indirectly, which is also the fuel for most renewable systems. among all renewable systems, photovoltaic system is the one which has a great chance to replace the conventional energy resources.solar panel directly converts solar radiation into electrical energy. solar panel is mainly m

11、ade from semiconductor materials. si used as the major component of solar panels, which ismaximum 24.5% efficient 2. unless high efficient solar panels are invented, the only way to enhance the performance of a solar panel is to increase the intensity of light falling on it. solar trackers are the m

12、ost appropriate and proven technology to increase the efficiency of solar panels through keeping the panels aligned with the suns position. solar trackers get popularized around the world in recent days to harness solar energy in most efficient way. this is far more cost effective solution than purc

13、hasing additional solar panels 3.iii. technology to enhance power output from solar panelincreasing the cell efficiency, maximizing the power output and employing a tracking system with solar panel are three ways to increase the overall efficiency of the solar panel4. improvement of solar cell effic

14、iency is an ongoing research work and people throughout the world are actively doing research on this. maximizing the output power from solar panel and integrating solar tracking system are the twoways where electronic design methodology can bring success. maximum power point tracking (mppt) is the

15、process to maximize the output power from solar panel by keeping the solar panels operation on the knee point of p-v characteristics.a number of mppt algorithms have been developed and employed around the world 5. mppt technology only offers the maximum power that can be received from a stationary a

16、rray of solar panels at a particular time; it cannot, however, increase the power generation when the sun is not aligned with the system. automatic solar tracker increases the efficiency of the solar panel by keeping the solar panel aligned with the rotating sun.solar tracking is a mechanized system

17、 to track the suns position that increases power output of solar panel 30% to 60% than the stationary system 6. a few design methodology of solar tracking system has been proposed in recent days 7-9.led (light emitting diode), light-emitting diode, is a kind of ability to electric energy into visibl

18、e light solid state semiconductor devices, it can be directly put dianzhuan into light. the heart of the led is a semiconductor chip, chip attached on a bracket, at the end of the end is negative, the other end connected to the power of the anode, the whole chip is encapsulated by epoxy resin. semic

19、onductor chip consists of two parts, one part is a p-type semiconductor, dominated by holes in it, the other end is n-type semiconductor, here is mainly electronic. but this two kinds of semiconductor connected, forming a p-n junction between them. when a current flows through a wire to the chip, th

20、e electron will be pushed p area, electron and holes in the p zone compound, then will be issued in the form of photon energy, this is the principle of led light. and the wavelength of light was the color of the light, is determined by the formation of p-n junction material. initially led is used as

21、 the indicator light instrument and then all kinds of light color of led traffic light and display screen has been widely applied in large area, produced good economic and social benefits. 12-inch red traffic lights, for example, in the united states could have been used long life, low light efficie

22、ncy of 140 - watt incandescent lamp as light source, it produces 2000 lumens of white light. after the red filter, light loss 90%, only 200 lumens of red light. and in the light of the new design, lumileds companies adopted 18 red led light source, including circuit loss, total power consumption of

23、14 watts, can produce the same light. car light is also an important field of led light source. for general lighting, people need more white light sources. hair white light led successful development in 1998. this led to gan chip and yttrium aluminum garnet (yag) packaging together. gan hair blue ch

24、ip (lambda p = 465 nm, wd = 30 nm), high temperature sintering of yag phosphors containing ce3 + yellow light shot after the blue light excitation, peak 550 m nled lamp. blue led substrate is installed in the bowl reflection cavity, covered with thin layer of resin mixed with yag, about 200-500 nm.

25、led substrate from the blue part is absorbed phosphor to another part of the mix blue with yellow light from fluorescent powder, we can get more white light. for ingan/yag white leds, by changing the chemical composition of yag phosphors and adjust the thickness of phosphor layer, can obtain a varie

26、ty of white light color temperature 3500-10000 k. this by the method of blue leds for white light, simple structure, low cost, high technical maturity, so use the most.compared with the traditional glow of light, led light source is low pressure microelectronics products, successfully combines compu

27、ter technology, network communication technology, image processing technology and the embedded control technology, etc. traditional led lights used in the chip size is 0.25 mmx0.25 nm, and the size of the led lighting is typically mmx1.0 in 1.0 mm and above. led bare chip forming work table structur

28、e, the inverted pyramid structure and flip chip design can improve the luminous efficiency, thus more light. led packaging innovation including the design of high conductivity metal base, flip chip design and bare plate casting type lead frame and so on, these methods can design a high power, low th

29、ermal resistance of the device, and the device of the illumination intensity of illumination is greater than traditional led products. a typical high flux led device can produce several lumens to dozens of lumen flux, update the design can be integrated in a device more leds, or multiple devices can

30、 be installed in a single assembly, so that the number of lumen output is equal to the small bulb. for example, a high power 12 monochromatic led chip light energy device can output 200 lm, the consumed power between 10 15 w. the application of led light source is very flexible, used as the dot, lin

31、e, face various forms of lightweight products; led control is extremely convenient, as long as adjust current, can be arbitrarily adjusted light; a combination of different light color changing, the sequential control circuit, can achieve more dynamic change of rich and colorful effect. led has been

32、 widely applied in all kinds of lighting equipment, such as a battery-powered flashlight, mini voice control lamp, security lighting, outdoor and indoor stair floodlight roads and buildings and tag continuous lighting. the emergence of white led is led from the identification to the illumination fun

33、ction across a substantive step. white led closest to the sun, more can well reflect the reality of the irradiation object color, so from a technical perspective, white led is undoubtedly the most cutting-edge led technology. white led has began to enter some application field, emergency lights, fla

34、shlights, flash and other products appeared, but because the price is very expensive, so hard to popularize. white led popularization is the premise of price decline, and prices must be formed in the white leds is possible after a certain market scale, integration of the two end depends on technolog

35、y progress. iv. microcontrollerthe atmega32 microcontroller has been used in the prototype. microcontroller is the heart of overall system.atmega32 microcontroller requires a 5 volt regulated voltage supply. 7805 voltage regulator is used to providefixed 5 volts supply to the microcontroller .atmega

36、32 has some features such as analoge comparator (ac), analog to digital converter (adc), universal synchronous asynchronous receiver transmitter (usart), times etc. 13. utilization procedure of these features is given below1)analog comparator:there are two pins which are known as analog input 0 (ain

37、0) and analog input 1 (ain1). two analog voltage signals coming from two junctions of photo resistor circuit are fed to these pins. there is a bit called analog comparator output (aco) which is set to either 1 or 0.aco = 01 vain0 v ain1vaini vain02) analog to digital converter:among 8 analog to digi

38、tal converter input pins adc0 and adc1 have been used; where vvt ,is expected. differential input is converted into digital value and the most 8 significant bits are defined 10 adcadc asadc_result to compare with threshold.adc_result= v adc0 v adc1 digitalthis threshold value, set according to the p

39、hoto resistor response against the solar radiation intensity, is provided, sinceadc_result alone might be insufficient for rotation of motor. and if adc_result threshold; motor rotates one step.3) timers:built-in timer of atmega32 is utilized to create delay. the earth rotates on its own axis, with

40、respectto the sun 360 in a day and so it rotates, (360/24=) 15 an hour or 3.75 in 15 minutes. delay for 1.5 minutes and 15 minutes are required. these delays are mentioned as short delay and moderate delay respectively. the lasthour before sunset will provide additional energy to rotate thepanel in

41、the initial position and so the tracker no more rotatesto the west rather it will rotate reversely. as 2 hours in day time are not considered for tracking, (215=) 30 of rotationis not required to be done by the solar tracker. half stepping of stepper motor is considered which gives 3.75 rotation ine

42、ach stepping; approximately (180-30)/3.75=) 40 rotations are required in each day to track the sun at daylight. count is used for counting the number of wait states when weather is cloudy and adc does not permit to rotate the motor.v.charge controllera charge controller monitors the state-of-battery

43、 to insure that when the battery needs charge-current it gets it, and also insures the battery isnt overcharged. connecting a solar panel to a battery without a regulator seriously risks damagingthe battery and potentially causing a safety concern.charge controllers (or often called charge regulator

44、) are rated based on the amount of amperage they can process from a solar array. if a controller is rated at 20 amps it means that you can connect up to 20 amps of solar panel output current to this one controller. the most advanced charge controllers utilize a charging principal referred to as puls

45、e-width-modulation (pwm) - which insures the most efficient battery charging and extends the life of the battery. even more advanced controllers also include maximum power point tracking (mppt) which maximizes the amount of current going into the battery from the solar array by lowering the panels o

46、utput voltage, which increases the charging amps to the battery - because if a panel can produce 60 watts with 17.2 volts and 3.5 amps, then if the voltage is lowered to say 14 volts then the amperage increases to 4.28 (14v x 4.28 amps = 60 watts) resulting in a 19% increase in charging amps for thi

47、s example.charge controllers also offer low voltage disconnect (lvd) and battery temperature compensation (btc) as an optional feature. the lvd feature permits connecting loads to the lvd terminals which are then voltage sensitive. if the battery voltage drops too far the loads are disconnected - pr

48、eventing potential damage to both the battery and the loads. btc adjusts the charge rate based on the temperature of the battery since batteries are sensitive to temperature variations above and below about 75 f degrees.1)battery:the deep cycle batteries used are designed to be discharged and then r

49、e-charged hundreds or thousands of times.these batteries are rated in amp hours (ah) - usually at 20 hours and 100 hours. simply stated, amp hours refers to the amount of current - in amps - which can be supplied by the battery over the period of hours. for example, a 350ah battery could supply 17.5

50、 continuous amps over 20 hours or 35 continuous amps for 10 hours. to quickly express the total watts potentially available in a 6 volt 360ah battery; 360ah times the nominal 6 volts equals 2160 watts or 2.16kwh (kilowatt-hours). like solar panels, batteries are wired in series and/or parallel to in

51、crease voltage to the desired level and increase amp hours.the battery should have sufficient amp hour capacity to supply needed power during the longest expected period no sun or extremely cloudy conditions. a lead-acid battery should be sized at least 20% larger than this amount.if there is a sour

52、ce of back-up power, such as a standby generator along with a battery charger, the battery bank does not have to be sized for worst case weather conditions.the size of the battery bank required will depend on the storage capacity required, the maximum discharge rate, the maximum charge rate, and the

53、 minimum temperature at which the batteries will be used. during planning, all of these factors are looked at, and the one requiring the largest capacity will dictate the battery size.in this specific application, and taking into account thechanges of solar radiation during the day and, consequently

54、, the energy available, the battery bank charge algorithm willpresent three different modes: if the panel available current is lower than 0.1cah, the converter will find the maximum power point (mppt)in order to provide the highest current possible for thebattery bank (area under the current level,

55、see figure 2). if the panel available current is higher than 0.1cah, theconverter limits the current to 0.1cah, and disables thesearch for the maximum power point. if the batteries are already charged, the control algorithmwill apply a constant voltage level, in order to keep thebatteries charged.le

56、ad-acid batteries are the most common in pv systems because their initial cost is lower and because they are readily available nearly everywhere in the world. there are many different sizes and designs of lead-acid batteries, but the most important designation is that they are deep cycle batteries.

57、lead-acid batteries are available in both wet-cell (requires maintenance) and sealed no-maintenance versions. agm andgel-cell deep-cycle batteries are also popular because they are maintenance free and they last a lot longer.vi. conclusionthis paper has studied about various advancements in the fiel

58、d of solar based led street light. the use of solar tracking system has greatly increased the system and has helped to increase its overall output.whereas the use of charge control circuit in the solar based led street light has not only helped in saving the battery power but also in preventing the

59、battery from getting deep discharged, overcharged, thereby conserving a lot of energy.r eferences1 design and construction of an automatic solartracking system md. tanvir arafat khan, s.m. shahreartanzil, rifatrahman, s m shafiulalam*, member, ieee department of electrical and electronic engineering,