Equally long as the Sun radiances, there is no decease for solar energy. The solar energy is available in big sums and besides free of cost, this evokes more involvement in the use of this energy. Solar energy has many utilizations in our twenty-four hours to twenty-four hours life ; it can be used to bring forth electricity utilizing photo-voltaic cells. The procedure of change overing solar energy into electricity is called as solar power. The solar energy can besides be used for warming and chilling edifices with aid of solar chimneys. Over the yearss many engineerings have been developed to tackle solar energy.
The future tendency is alternate energy ; most of the engineerings developed today are related to alternative energy straight or indirectly depending on solar energy. Solar energy is really critical to back up life on Earth. Heat and visible radiation from Sun along with the other renewable beginnings of energy such as hydropower, geothermic and wind power, if efficaciously used, can be really utile to mankind.
Use of solar energy makes us dependent on renewable beginnings of energy. Since solar energy is available at free of cost, we do non necessitate to pass money on non-renewable beginnings of energy. This factor contributes to put in developing of different engineerings to tackle solar energy.
Solar energy has many applications runing from house clasp uses to industrial fabrication. Solar energy can besides be used in Fieldss like transit and agribusiness sectors. Over the period of clip many engineerings have been developed for the different ways to tackle the solar energy. The handiness of solar energy in big sums makes it even more utile and can be use in assorted applications from little to big exposure Gur workss.
General Statement of the Problem
In order to bring forth solar power in an optimum manner, solar panels that are used to capture Sun ‘s beams need to be rotated based upon the motion of the Sun. The bing solution for revolving solar panels use a rotary motion system that is based on clip of the twenty-four hours and that is really specific to the location of the system. Figure 1 shows the basic diagram of the solar tracker. Some of the systems besides use a GPS ( Global Positioning System ) to indicate the location of the installing of the system. These sort of systems are complicated to construct and give consequences for all the geographical locations ( We need a GPS for location and a microcontroller for seting the rotary motion coordinates based on the GPS end product ) as way of Sun ‘s beams and motion of the Sun varies from one location to other. The job faced by most of these executions is that they are excessively complex to be reproduced in big measures. Advanced technology thoughts need to be developed to construct a simple system that can be built cost efficaciously but still serves the intent of maximising solar energy.
To accomplish more robust execution with maximum efficiency and duplicability on big graduated table, a system that takes feedback from the way of the Sun by utilizing two light feeling rectifying tubes is proposed. These rectifying tubes convert light energy to electrical signals that are finally read by the microcontroller, which can be seen in Figure 2.
Figure 1. Basic Diagram of Solar tracker
Microcontroller uses a stepper motor to turn the solar panel by the needed angle. The proposed system is simple since it does non necessitate GPS, accurate Real Time redstem storksbills or manual intercession.
The comparing between go outing executions and executions with light detector reveals tonss of advantages of the later. The electronic system is simple to construct as we need a microcontroller and some back uping circuits. We besides use the construct of negative feedback to ticket tune the direct on of rotary motion of solar panel.The system can rectify important mistakes in the electronic system that by and large occur due to voltage fluctuations and aging as we have negative feedback to state us if we reach optimum place. The proposed system besides has the extra advantage that it does non necessitate to take into consideration the latitude at which system is installed ( northern latitudes will necessitate more southern joust if non for car rectification of way ) . Thereby it frees up any technology clip required for custom installing.
This undertaking seeks to research a simple, cost effectual, robust solution to set the panels utilizing detectors, 555 timer, microcontroller and stepper motor. The thought behind this proposal consists of two exposure transducers that collect light from two different places on the solar panel and converts this visible radiation to analog electromotive force. The 555 timer converts this electromotive force to digital format which can be fed to the microcontroller. The microcontroller can take inputs from two detectors and make up one’s mind if we are roll uping maximal light or we need to alter place.
Figure 2. Pictorial Representation of solar tracker.
The restrictions of this execution include the proposed system is non able to feel visible radiation in a cloudy environment. This should non be a major restriction since light aggregation during a nebulose twenty-four hours is at lower limit. There might be some care needed to do certain that detectors are non covered by dust and barricade the visible radiation. Some of these restrictions can be overcome by holding a backup Real Time Clocks based system.
Definition of Footings
Power Supply: Voltage regulated power supply supplies power to all the electronics. This is by and large off-the- shelf additive regulator that outputs supply electromotive force required by all the electronics while filtrating out any supply fluctuations.
Input Photo Transducer: Detector that converts visible radiation to electric signals which can be processed by on board electronics is a photo transducer.
555 timer: All existent universe signals are analog with some noise. 555 timer as Schmitt trigger removes unwanted noise and change over them to digital signal.
Microcontroller: This is digital treating engine that is at the bosom of the system. It takes digital signals from 555 timer and gives the end product to stepper motor to turn in the right way.
Stepper Motor: Mechanical component that turns the solar panel way.
1. There is an of all time increasing demand for solar power.
2. Solar panels are needed to bring forth electricity from Sun.
3. Solar panels need to orientate in the way of Sun to capture maximal Sunlight.
4. Best of capturing maximal sunshine is have light feeling exposure transducer.
A reappraisal of Related Literature
The first of all time automatic solar tracking system was presented in 1975 by Mcfee, who developed an algorithm to calculate entire standard power and flux denseness distribution in a cardinal receiving system solar power system. The consequence of mirror ‘s wavy curvature and besides the finding of tracking mistake of plane mirror heliostats in a rectangular array around a cardinal receiving system of the solar power system can be obtained by spliting the individual mirror into 484 parts, and so summing the part of all the mirrors. Flux denseness and entire power received from the Sun for a given location were calculated, including the shading effects and obstruction of next mirrors. The heliostats were assumed to be mounted harmonizing to altitude-azimuth values ( McFee, 1975 ) .
In the 90s, Maish developed a control system called Solar Trak, which provided Sun trailing, communicating, dark and exigency storage and control maps to drive one and two axis trackers manually. It has relatively better system dependability and truth as its control algorithm has self alignment modus operandi and ego seting motor propulsion clip. Its full twenty-four hours experimental consequences showed truth of better than +0.1 ( Maish, 1995 ) . Kalogriou ( 1996 ) proposed a solar trailing system that used individual axis solar concentrating systems and was chiefly suited for parabolic aggregators with good concentration ratios. This system was made up of Light dependent resistances ( LDRs ) . The LDRs detected the place and position of the Sun. Kalogriou used three LDRs: i¬?rst to observe the focal point of the aggregator, the 2nd to observe the cloud screen and the 3rd to feel twenty-four hours or dark. The LDRs generated an electrical signal that was fed to a D.C. motor ( 12V ) , which operated at a really low velocity. A velocity decrease gear box was used, which helped in revolving the aggregator ( Kalogirou, 1996 ) .
Open Loop Architectures
In 2004, Abdallah and Nijmeh designed an electromechanical, two axes sun tracking system with an open-loop algorithm and enhanced it by utilizing Programmable Logic Controller ( PLC ) for commanding the joust, gesture and place of solar panels. This system used two separate motors: one was used to drive the solar panels to set to the incline of the surface ( horizontal north-south axis ) and the other was used to drive the solar panels to set to the azimuth angle of the surface ( perpendicular axis ) . By utilizing the two traveling axes sun tracking system, the surface of the solar panels showed an addition in entire capturing of solar energy as compared to individual i¬?xed tilted surface. The experimental survey showed that the addition in the gathered energy increased by 41.34 % ( Abdallah & A ; Nijmeh, 2004 ) . In the same twelvemonth, Reda and Andreas worked on a new process to implement a bit-by-bit solar place algorithm. The algorithm derived the solar zenith, AZ and incidence angles based on parametric quantities as ecliptic longitude and latitude for average Equinox of day of the month, evident right Ascension and evident decline. The algorithm besides included some rectification parametric quantities as nutation in longitude, nutation in asynclitism, asynclitism of ecliptic and true geometric distance ( Reda & A ; Andreas, 2008 ) . In 2007, Chen and Feng developed a solar trailing system on the rule of linear optical non additive compensation. The traditional parallel detector consisted of a thin mask with a square aperture that was placed above a quadrant sensor.
The square aperture consisted of four slits of equal breadth. A projective image is formed on the sensor ‘s plane by the light of incident sunshine in different places of the sensor, depending on the comparative angle of the detector axis. As a consequence, in a traditional parallel solar sensor the AZ and lift angles are obtained by the basic geometrical rules by treating the signals. The end product signals vary non-linearly with the AZ and lift angles, i.e. , sensor sensitiveness depends on the incident angle of the sunshine. As a solution to this job, the writer ‘s modii¬?ed the aperture country per unit length varied in conformity with specii¬?c Torahs. Therefore, the nonlinear supplanting of the projective image on the sensor ‘s plane caused by additive alterations in the incident angle of the sunshine was compensated by the nonlinear aperture country per unit length such that the end product of the detector varied linearly with the input ( Chen & A ; Feng, 2007 ) .
History of Microcontrollers
The Microcontroller was foremost developed in the early 1970 ‘s by a company called Intel ( Integrated Electronics ) . Intel was a little company and its client refused to purchase the merchandise. So Intel decided to market its microprocessor as a all-purpose chipset, which was extensively used wherever digital logical french friess were used. The success of this microprocessor triggered Intel to research more on microprocessors and really shortly it developed a 4-bit microprocessor for general intent. 4004 is much more advanced and it is designed and marketed as a “ general intent ” chipset.
Subsequently, Intel in association with TI produced an 8-bit cardinal processing unit ( CPU ) with a 14-bit informations memory coach, which can turn to up to 16KB of memory. The CTC ( computing machine Terminal Corporation ) ordered Intel and Texas Instruments to construct them an 8-bit processor that can be used in terminuss. Soon CTC gave up its thought. Even so Intel and TI kept working on the undertaking and released a microprocessor 8008, which is able to turn to 16KB of memory and operation velocity of 300 000 operations per second. Later an updated theoretical account of 8008, i.e. 8080 was really shortly released which has operating scope of +5V, -5V and +12V utilizing NMOS engineering.
Detecting these developments in engineering, Motorola released its first of all time microprocessor, the 6800. Motorola was the lone company to do other peripherals such as 6820 and 6850. 6800 is an 8-bit with about the same specifications as of 8080. The architectures used in 8080 and 6800 differ a batch. The architecture used in Intel 8080 is a registry based. The registries are from AX, BX, CX, DX, and HL. All are 16-bit but are capable of being used as an 8-bit registry braces. So the registry AX can be used as two separate registries, i.e. AX can be used as AH and AL. Where AH a byte higher than AX, where as AL is is the old lower byte. In the similar manner each and every registry BX, CX, DX, and HL can be used as BH, BL, CH, CL, DH, DL, H, and L.
Besides Intel 8080 has separate I/O map. This is given individually to supply byte-wide input/output to hardware. Some particular instructions are used to execute either input or end product to the hardware. The direction for accepting a byte-wide input from it ‘s input port is IN. Similarly OUT is to end product a byte-wide end product to the end product port. The MOV direction is used to acquire entree to memory from a different memory map.
Motorola 6800 used “ Memory Mapped Input/Output ” . Memory mapped input/output is nil but sharing of the same memory map by both memory and byte-wide input and end product, which is different from Intel 8080. Besides the registry set consisted of two 8-bit collectors, i.e. A and B, and an index registry X. The index registry X is of 16-bits and this makes the registry set much smaller than Intel 8080. However little, these registries can back up a scope of turn toing manners. These turn toing manners are made up for few registries and simple scheduling. The informations input from the memory or from input beginning requires the usage of LDAA. This is used to compose informations to the memory or input/output requires the usage of STAA direction. The entree to register X is was through an ain set of instructions, i.e. LDX and STX.
As before both the companies Intel and Motorola have maintained differences in their development of farther microcontrollers. The Intel upgraded it ‘s 8080 to 8085, in 1977which is besides 8-bit processor like 8080 and is first 5V CPU gave ‘5 ‘ in the topographic point of ‘0 ‘ . Intel was really acute on upgrading microprocessors. Very shortly 8086, 8088 and subsequently 80186 were released. 800386 is a 32-bit processor and 80486 taking to the design of Pentium scope of microprocessors which are 64-bit processors. 80×86 and Pentium scope processors are specially designed for personal computing machine applications. They have big memory maps. Motorola ‘s microprocessors followed similar way by replacing 6800 with 6809, an 8-bit and so by 68000, a 16-bit. The microprocessors 68010, 68020, 68030 were used in many workstations and besides in personal computing machines like Apple MAC.
The most recent microprocessors in the present market usage Harvard architecture and usage of Reduced Instruction Set Computers ( RISC ) have led to the development of microcontrollers such as Microchip PIC.
Microcontroller 8051: Micro accountant is at the bosom of the system and following description gives an thought of this important constituent. The IC 8051 is a low-power ; high-performance CMOS 8-bit personal computer with 4K bytes of brassy memory. The pin diagram of 8051 is shown in Figure 3. The device is manufactured by Atmel and is compatible with comparable industry pin out. There is advantage of brassy memory because it is non-volatile. This allows a plan to be stored even when we lose power. Atmel IC 8051 combines a 8-bit CPU with Flash memory on a individual dice bit. It besides provides a highly-flexible and cost-efficient solution to many embedded control applications. criterion features that semen with IC are: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timers and counters, a five vector double degree interrupt architecture, full semidetached house consecutive port and oscillator along with clock circuitry. In add-on to all this characteristics mentioned, ATMEL 8051 is designed with inactive logic for operation down to zero frequence and it supports two package selectable power salvaging manners. The Idle Mode stops the CPU while leting the memory, timer counters, consecutive port and interrupt system to go on operation.
FiFigure 3. Pin Diagram of 8051
Figure 4.Block Diagram of 8051
The block diagram explains internal circuitry of Microcontroller which is Shown in figure 4. These inside informations are needed to understand and plan microcontroller utilizing embedded programming methods.
ULN 2003 7805: The ULN2001, ULN2002, ULN2003 and ULN2004 are high electromotive force, high current Darlington Arrays each one have seven unfastened aggregator Darlington pairs with common emitters shown in below Figure 5. Each Channel rated at 500mA and can defy peak currents of 600mA. Suppression rectifying tubes are included for inductive burden drive and the inputs are pinned opposite the end products to simplify board.
Figure 5. ULN 2003
There needs to be a driver placed, because the digital system and pins of microcontroller do non hold adequate current to drive the relay. The stepper motor ‘s spiral needs to be provided with 10mA of current in order to acquire energized, whereas the microcontroller pin provides a upper limit of 2 mA current.
555 Timer: The 555 massive timing circuit is a extremely stable accountant capable of green goods accurate clip holds, or oscillation. In the clip hold manner of operation, the clip is accurately controlled by external resistance and capacitance. For a stable operation as an oscillator, the free running frequence and the responsibility rhythm are both accurately controlled with two external resistances and one capacitance. The pin diagram of a 555 TIMER is Figure 6. The circuit may be triggered and reset on falling wave forms, and the end product construction can beginning or drop up to 200 mas.
Figure 6. 555 Timer
Stepper motor: There are several types of hoofer motors ; these can non be driven in the same manner. In this application note, we have chosen to drive a unipolar hoofer motor for more information you will happen strategies to place the other types of hoofer motors.
Figure 7. Stepper Motor
Unipolar Stepper Motor: Uni-polar hoofer motors are characterized by their center-tapped twists.
Figure 8. Uni-polar Stepper Motor
Bipolar Stepper Motor: Bipolar hoofer motors are designed with separate spirals.
Figure 9. Bipolar Stepper Motor
Variable Reluctance: Variable reluctance hoofer motor ( besides called intercrossed motors ) are characterized by one common lead.
Variable Reluctance Stepper Motor
Figure 10. Variable Reluctance Stepper Motor
Driving unipolar Stepper Motors: There are three ways to drive unipolar hoofer motors ( one stage on, two stage on or half measure ) , each one has some advantages and disadvantages.
There are two phases to screening out which wire is which in a 5 or 6-wire unipolar hoofer motor:
In screening out the wires as per their specifications for a 5 or 6 wire unipolar hoofer method, a two measure process is followed.
The opposition between the braces of wires is checked with the aid of ohmmeter by insulating the common power wire. The common power wire can be recognized by the opposition it offers, that it has merely half of the opposition between it and all others. This is due to the ground that the common power wire carries merely one spiral, whereas other wires carry two spirals between them. Therefore merely half of the opposition is observed in common power wire.
Following measure is to place the wires to the spirals. Supplying a fixed sum of electromotive force on the common power wire, while maintaining one of the other wires grounded does this. Each of the three staying wires is grounded one by one in bend, and the consequences are observed. A wire is selected and grounded, thereby assumed as connected to gyrate 4. Each of other three wires is grounded in bend, and in the procedure the rotor turns clockwise for a peculiar grounded wire. It is assumed as connected to gyrate 3. Keeping these two wires as such, anchoring one of the staying wires will do the rotor bend anticlockwise, which is assumed as connected to gyrate 1. The wire, which makes the motor do nil after anchoring it is assumed as connected to gyrate 2.
Figure 11. Center tapped weaving
LDR ( Light Dependent Resistor ) : The LDR is a constituent that changes its opposition with assorted degrees of visible radiation. In the dark, the LDR presents a really high opposition like above 1 Mega Ohm. This opposition will fall below 100ohm under direct Sun visible radiation. The LDR is a resistance, so that the current flow in the either way. Although the LDR is really sensitive, seeing the degrees of visible radiation that our eyes ca n’t, the LDR is a slow device. Fast light alterations ca n’t be detected by an LDR. The upper bound of a frequence response of an LDR is about 10 KHz. If you need to observe faster visible radiation alterations, you can utilize detectors such as photodiodes and exposure transistors.
Using LDR is really easy, since it can straight bias semi music director for devices such as transistors, SCRs, ICs etc. , LDRs can be used as electronic eyes in applications affecting robotics, mechatronics. As in human oculus, a lens can be added to heighten the public presentation of an LDR in a peculiar application. By puting a convergent lens in forepart of an LDR, we can pick up more visible radiation from one way, increasing sensitiveness and adding directionality. LDRs can be found in different sizes and formats but, in general, their electrical features do non differ much.
Figure 12: LDR & A ; its Symbol
Summary of State of the Art
Most of the available literature describes unfastened cringle architectures for solar panel rotary motion. We have besides reviewed the history and architecture of microcontroller development as microcontrollers are the bosom of the electronic system used to command solar panel.
Method of probe
This undertaking seeks to research a simple, cost effectual and robust solution to set solar panels utilizing detectors ( photo transducer ) , 555timer, microcontroller and stepper motor. The thought behind this proposal consists of two exposure transducers that collect light from two different places on the solar panel and converts this visible radiation to analog electromotive force. A 555timer converts this electromotive force to digital format which can be fed to a microprocessor. The microprocessor can take inputs from two detectors and make up one’s mind if we are roll uping maximal visible radiation of if we need to alter place.
There are two really clear advantages to this solution. One is: since this solution is closed loop i.e. take light input as a variable, accommodations are made till optimum point is reached. Besides, we can plan that accommodation to be made merely 3 or 4 clip a twenty-four hours non to do failure of mechanical parts. Second advantage is that all the portion of this system is off the shelf electronic constituents that bring down cost of execution for mass production.
Description of Subjects and Equipment
To construct the electronic systems as described we need several constituents that can be divided into three classs depending upon where they fit into the overall system. Block diagram is shown in Figure 13.
1 ) Light dependent Resistors ( LDRs ) : These detectors capture light and need to be mounted on the top of solar panels to capture visible radiation. This undertaking will hold electrical wires with appropriate conditions insularity, to link LDRs to rest of electrical system. In the presentation system that proves research constructs, the conditions insularity is non given precedence, but is emphasized as a demand for volume production of paradigm.
2 ) Electronic system: A Electronic system consists of a printed circuit board ( PCB ) that connects assorted french friess as described in the conventional diagram is shown in Figure 14. These connexions are made with thin Cu metal that is coated on the top of insulating board to maintain assorted signals electrically isolated. Once the needed connexions are drawn, the PCB is coated with insulating stuff to forestall inadvertent short circuits in existent operation. Electronic french friess like Microcontroller, 555 timer and ULN ( buffer ) . Passive electronic constituents like resistances and capacitances to give right currents and electromotive forces to micro chips. A transformer that takes AC power from brinies and stairss down to a lower electromotive force and span rectifier that converts this lower AC electromotive force into DC electromotive force 5V battery.
A lodging ( fictile box ) is needed to maintain all these constituents together in volume production. In a typical place solar system, this portion of the system is unbroken indoors to screen from outside conditions.
3 ) Stepper Motor: A motor is needed to turn the solar panel. This motor needs to construct into the flexible joint that holds solar panel to a lasting construction.
This undertaking proposes to show the constructs of closed cringle control of solar tracking system utilizing off the shelf electronic constituents that can be ordered from electronic constituent houses like Mouser electronics or Dig key. The undertakings that are involved in execution are traveling through a list of suited constituents that fit the system. For illustration there are assorted programmable micro accountants with different grades of complexness of characteristics. We should take the microcontroller that performs the needed arithmetic operation without adding complexness or cost that is non needed. A elaborate description of each of the chosen constituents follows in the study. Once the french friess are chosen, we need to look at electromotive force demands of these french friess and besides any resistances or capacitances that need to add to the conventional diagram for these french friess to map as specified in their datasheets.
Figure 13. Block Diagram of Solar Tracker
After the conventional diagram is finalized, we need to construct a printed circuit board utilizing package to construct PCBs and have the PCB industries and all the french friess soldered on. The complete system demand to be built with needed transformers and demonstrated to turn out the construct.
Research Design and Procedures
The aim of this undertaking is to command the place of a solar panel in conformity with the gesture of Sun and do certain that solar panel gaining controls maximal sum of solar energy possible.
The angle at which Sun rays autumn on the surface of the solar panel determined the sum of energy captured by the solar panel. As described in statement of intent this undertaking explores the ways to car adjust place of solar panel to capture maximal sunshine.
This undertaking is designed with solar panels, LDR ( Light dependent resistance ) detectors, 555 Timer, microcontroller, stepper motor and its drive circuit. In this undertaking two LDRs are fixed on the solar panel at two distinguishable points.
LDRA varies the opposition depending upon the light autumn. Since two detectors are located at two different topographic points on the panel, we get two distinguishable oppositions matching to the manner panel is oriented. This opposition is converted into a electromotive force by giving a bias current to LDRs. The born-again electromotive force is given as input to 555Timer.
Inside 555Timer the varied opposition is compared with a mention electromotive force and converted into a digital signal. Then the born-again digital signal is given as the input of the microcontroller.A Microcontroller receives the two digital signals from the detector circuit and compares them. Unless the solar panel is in optimum place where this undertaking gets maximal solar energy, the LDR signals are non equal. When there is a difference between LDR electromotive force degrees, the microcontroller plan drives the stepper motor towards optimum place or normal incidence of sunshine. This as a feedback system as explained above since this rectification mechanism keeps go oning until solar panels are in optimum place.
Description of Measures Employed
LDR: LDR is represented by U6 and U8 in the conventional diagrams. For electrical mold intents this is nil but a resistance whose value is controlled by the visible radiation that falls on it. To feel the LDR opposition value, it is connected in series with 10K resistance therefore organizing an effectual resistive splitter. When light falls on the LDR, its opposition will be low and electromotive force at pin2 of 555timer will be near to provide electromotive force ( VDD ) . When there is no visible radiation on LDR, the electromotive force at same pin 2 will be near to land at 0V. Thus it can demo the sum of light falling on LDR by looking at electromotive force on pin2 of 555timer.
555timer: This circuit is used to filtrate any noise coming out of LDR. Pin2 of 555timer has noisy electromotive force that depends on sum of light falling on LDR. This electromotive force can be digitizing such that any electromotive force above two tierce of supply electromotive force will be an ON place and any electromotive force below one tierce of supply electromotive force will be an OFF place. 555 timer as connected in conventional shown in Figure18 will move as Schmitt trigger ( A digitizing buffer with noise filtration built in ) . The resistance R1 and capacitance U9 determine the sum of noise filtration we are acquiring out of this circuit. Capacitance U5 helps to take any noise from land line of the power supply.
Microcontroller: All microcontrollers need a maestro clock frequence to run their operation. This clock frequence is generated utilizing accurate vitreous silica crystal.A In Figure 19 X1 is the quartz crystal and U10, U11 represent the needed electrical capacities that adjust the frequence of maestro clock. R5 is once more a noise filtering resistance for this crystal oscillator. Capacitance C1 filters the power supply noise traveling into microcontroller. Given that microcontroller is the chief portion of the system, we have a dedicated noise filtrating capacitance on its power supply line.
Buffer: ULN 2003 is merely a buffer that takes digital signals of microprocessor and change over them into a format that can provide big sums of currents needed by stepper motor. This circuit is non required from a logical diagram of the circuit, but, is inserted to take attention of practical necessities of driving a hoofer motor. Figure 14. Conventional Diagram of Solar tracker
Stepper Motor: Stepper motor is a simple DC motor that runs based on sum of electromotive force applied to its inputs and will be used to turn solar panels.
In this proposal light dependent resistances are used to track the gesture of Sun by feeling the Sun beam. Due to the light fluctuations the end product of the light dependent resistance alterations consequently. In order to command the drastic alterations at end product that is motion the solar panel due to fluctuation of current at end product of the light dependent resistance, 555 timer ( Schmitt trigger ) is used. Schmitt trigger is type of comparator, built by utilizing 555 timer. It measures the input whether it is above or below the threshold. The threshold varies to do it less likely that the end product will exchange quickly back and Forth due to a noisy input near the threshold. This Schmitt trigger circuit is a inverting buffer ( NOT gate ) , so the end product is high when the input is low ( below threshold1/3 of Vcc ) and end product is low when the input is high ( above threshold 2/3 of Vcc ) .
In order to acquire these threshold electromotive forces ( signal conditioning ) at the input of the 555 timer, a variable resistance is used in series with the LDR to organize electromotive force splitter. The dark resistance of LDR used in this undertaking is about 1M ohm and it decreases 4K ohms when illuminated byr more light, so the series variable resistance is selected consequently to 10K ohms. 120 K ohms resistance is connected in series with 0.01uf to filtrate the noise at input of 555 timer. The signals from the two detectors are compared by utilizing the microcontroller scheduling and produces end product to drive the stepper motor.
Figure 14 shows the connexion of discussed constituents. As we can see all the constituents are chosen to utilize the same DC electromotive force of 5V that will be produced by the rectifier. Primary concerns in implementing the system are: All electronic constituents require a fixed and regulated power supply for them to work as specified. If the circuit has signaled that are connected to many constituents, undertaking demands to measure the thrust strength or the current that is supplied by the bit that outputs the signal. If microcontroller does non hold sufficient thrust strength end product from micro accountant, we need to utilize a bit called buffer integrated circuit to give sufficient current.
Choosing 555 timer:
Given that solar tracker system is a closed cringle system, we get a batch of flexibleness in footings of taking constituents. If we choose an ADC that has less truth and if gives a consequence that is somewhat different from the most accurate consequence, we can ever rectify this as we get feedback until the solar panel is in optimum place. Since this is a research undertaking we can show that we can acquire off with really low truth convertors by utilizing a 1-bit ADC which is basically a digital inverter. This thought is implemented utilizing a 555 timer in a Schmidt trigger constellation. Schmitt trigger constellation is required to extinguish any noise from LDRs.
Choosing a buffer for microcontroller end products:
As discussed above, microcontroller end products might non hold adequate thrust strength to supply necessitate current to stepper motor. Digital systems and microcontroller pins lack sufficient current to drive the relay. While the stepper motor ‘s spiral needs around 10ma to be energized, the microcontroller ‘s pin can supply a upper limit of 1-2mA current. For this ground, we place a buffer driver between microcontroller and relays.
Choosing a stepper motor:
Uni-polar hoofer motors with centre tapped weaving are ideally suited for our application since we have a individual power supply that is needed to power both the hoofer motor and remainder of the electronics. Having a centre tapped stepper motor lets us use the low electromotive force most efficaciously since we are efficaciously duplicating the electromotive force in a centre tapped transformer.
Theoretically we have two picks to power the electronic system. We could utilize the DC power supplied by the solar panel to power all the electronics and the stepper motor or we can acquire power from AC brinies. Both instances need step down from a higher electromotive force to lower electromotive force.
We choose to acquire power from the brinies for several grounds: It is easy to step down AC electromotive force utilizing a transformer.AC power would be more dependable on a cloudy twenty-four hours. Most of the solar panels are connected to grid anyhow. So, acquiring AC power for electronics does non set any excess demands on the system.