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Acknowledgments:
Duringour graduation studiesat An-Najah National University, severalpersons
collaborated directly and indirectly with our work. Without their supportitwould be
impossible for us to finish this work. That is why we wish to dedicate this section to
recognize their support.
Expressinga sincere acknowledgementwewill start it to our advisor, Dr. KamelSubhi
because he gave usthe opportunity to work under hisguidance and supervision. We
received motivation, encouragementand supportfrom him. We also want to express
our gratitude to DR. Maher Khamash the head of department of electrical and
telecommunication engineeringfor his continuouswork to raise this departmentlevel
up and Dr. Marwan Mahmoud for beingthe encyclopediaof the power electronics
principlesand the expert in the practical applicationsof it.
At last, but the most importantwe would like to thank our families, for their
unconditionalsupportand AbdullahHanawi the electrical workshop supervisor.
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Table of Contents
CHAPTER 1......................................................................................................................................................................................................8
INTRODUCTION........................................................................................................................................................................................................8
1.1 Over view.....................................................................................................................................................................................................8
1.2 Motivations for carrying out the project : .............................................................................................................................................9
1.3 Report Organization:.................................................................................................................................................................................9
CHAPTER 2...................................................................................................................................................................................................10
CONSTRAINTS, STANDARDS ANDEARLIER WORK..................................................................................................................................................10
CHAPTER 3...................................................................................................................................................................................................12
LITERATURE REVIEW.............................................................................................................................................................................................12
3.1 Types of lamps used in streetlights.......................................................................................................................................................12
3.2 Hardware and components: ..................................................................................................................................................................15
3.3 Theories and circuit analyses.................................................................................................................................................................24
CHAPTER 4...................................................................................................................................................................................................30
METHODOLOGY.......................................................................................................................................................................................................30
CHAPTER 5...................................................................................................................................................................................................32
SOFTWAREWORKS...................................................................................................................................................................................................32
5.1 Matlab .......................................................................................................................................................................................................32
5.2 Arduino UNO ............................................................................................................................................................................................44
CHAPTER 6...................................................................................................................................................................................................46
RESULTS ANDANALYSIS.........................................................................................................................................................................................46
6.1 The triac dimmer results.........................................................................................................................................................................46
6.2 The IGBT dimmer results ........................................................................................................................................................................47
CHAPTER 7...................................................................................................................................................................................................49
DISCUSSION ANDECONOMICAL..............................................................................................................................................................................49
7.1 Discussion.................................................................................................................................................................................................49
7.2 Economical advantage ..........................................................................................................................................................................49
CHAPTER 8...................................................................................................................................................................................................50
CONCLUSION...........................................................................................................................................................................................................50
REFERENCES................................................................................................................................................................................................51
APPENDIX.....................................................................................................................................................................................................52
Appendix A.......................................................................................................................................................................................................52
Appendix B.......................................................................................................................................................................................................53
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List of figures:
CHAPTER 3
FIG.3.1 : THEAOTO CONTROLSTREET LIGHT CIRCUIT...................................................................................................................................14
FIG.3.2 : THEOUTPUT OF THE BRIDGE ............................................................................................................................................................16
FIG.3.3 : CIRCUITSYMBOLFOR ANOPTOCUPLER ..........................................................................................................................................17
FIG.3.4 : THE TRIAC SYMBOL AND SIMPLIFIED CROSS SECTIONOF THEDEVICE ......................................................................................19
FIG.3.5 : THECIRCUIT USED IN THE SECOND DIMMER ..................................................................................................................................21
FIG.3.6 : BASIC TYPEOF DIMMER .....................................................................................................................................................................23
FIG.3.7 : TRIAC OPERATION ...............................................................................................................................................................................24
FIG.3.8 : PERFORMANCEOF ZERO CROSSINGDETECTIO .............................................................................................................................26
FIG.3.9 : THE DUTY CYCLE...................................................................................................................................................................................27
FIG.3.10 : THE EFFECTOF DUTY CYCLE AT THEAVERAGE VALUE ................................................................................................................27
FIG.3.11 :(95%) OF DUTYCYCLE .......................................................................................................................................................................28
CHAPTER 5
FIG.5.1 : THESIMULATION CIRCUITFOR AUTO STREET LIGHT CONTROL CIRCUIT ...................................................................................31
FIG.5.2 : VOLTAGEIN DIFERENT FIRING ANGLE ( VREFF =0) .......................................................................................................................................33
FIG.5.3 : VOLTAGEIN DIFERENT FIRING ANGLE ( VREFF =.2).......................................................................................................................................34
FIG.5.4 : VOLTAGEIN DIFERENT FIRING ANGLE ( VREFF =.4).......................................................................................................................................34
FIG.5.5 : VOLTAGEIN DIFERENT FIRING ANGLE ( VREFF =.7).......................................................................................................................................35
FIG.5.6 : VOLTAGEIN DIFERENT FIRING ANGLE ( VREFF =.9).......................................................................................................................................35
FIG.5.7 : FUNCTION OF CURRENT WHEN ( VREFF =0 ) ...............................................................................................................................................36
FIG.5.8 : FUNCTION OF CURRENT WHEN ( VREFF =.2 ) ..............................................................................................................................................36
FIG.5.9 : FUNCTION OF CURRENT WHEN ( VREFF =.4 ) ..............................................................................................................................................37
FIG.5.10 :FUNCTION OF CURRENT WHEN ( VREFF =.7 )............................................................................................................................................37
FIG.5.11 :FUNCTION OF CURRENT WHEN ( VREFF =.9 )............................................................................................................................................38
FIG.5.12 :CHANGEIN POWER WHEN ( VREFF = 0) ....................................................................................................................................................39
FIG.5.13 :CHANGEIN POWER WHEN ( VREFF = .2) ...................................................................................................................................................39
FIG.5.14 :CHANGEIN POWER WHEN ( VREFF = .4) ...................................................................................................................................................40
FIG.5.15 :CHANGEIN POWER WHEN ( VREFF = .7) ...................................................................................................................................................40
FIG.5.16 :CHANGEIN POWER WHEN ( VREFF = .9) ...................................................................................................................................................41
FIG.5.17 :SIMULATION CIRCUITFOR IGPT ................................................................................................................................................................41
FIG.5.18 :OUTPUT VOLTAGEWHEN ( DUTY CYCLE =.75) ...........................................................................................................................................42
FIG.5.19 :OUTPUT VOLTAGE WHEN ( DUTYCYCLE =.6) .............................................................................................................................................43
FIG.5.20 :OUTPUT VOLTAGE WHEN ( DUTYCYCLE =.5) .............................................................................................................................................43
FIG.5.21 :OUTPUT VOLTAGE WHEN ( DUTYCYCLE =.4) .............................................................................................................................................44
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List of tables:
CHAPTER 3
Table 3.1 lamp type comparison : ...............................................................................................................................................................13
CHAPTER 7
Table 7.1 the percentage of dimming and power consumption during a day : ..................................................................................48
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Nomenclature:
LED : Light emitting diode
PMW : Pulsewidth modulation
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Abstract
Recently, the electrical power supplierstry to meet the increasing demand on the
electrical power in oneof two ways. Firstly, through usingrenewable energy resources
like solar energy and wind energy. Secondly, through effective managingthe electrical
power such as reducing the losses through usingnew approachesin technologies. This
project introducestwo approaches to effectively reducethe electrical power used in
street lighting through auto controlintensity of the street light.
The intensity of street lights is required to be kepthigh duringthe peak hours. Asthe
traffic on the roads tendsto decrease slowly in late nights, the intensity can be reduced
progressively till morningto save energy. Thus, the street lights switch ON at the dusk
and then switch OFF at the dawn automatically. The process repeats every day.
One way to achieve this is to usea power electronic circuit consisting of a thyristor and
its controlcircuit. This circuit willbe installed on the street light cable and by
controlling the firing angle of the thyristor, the intensity of the street light will change.
The second way to achieve auto intensity control is through using white Light Emitting
Diode(LED) whereintensity control is possible by pulsewidthmodulation.. The
electrical source that is used here willbe solar cell
Arduino programmablemicrocontroller isengaged to providedifferentintensitiesat
the differenttimes of night usingPWM technique in the two projects.
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Chapter 1
Introduction
1.1 Over view
In this projectan auto controlof the street lights will be doneby usingpower
electronics circuit which consists of small components, also this method is cheap.
Illumination Intensity of street lighting changes according to the time in the night. For
examplethe illumination intensity decreases because there is no need to the same
amountof lightening in the street at certain hoursof the night.
The illumination intensity of the street light lamps is directly related to the applied
voltage. And hence, by usingcontrolled power electronic devices such as the triac, it is
possible to obtain a variable voltage using differentfiringangles and hence obtaining a
control of the street light intensity.
The rest of the functionality of the system is provided by an Arduino takes an interrupt
signal from the zero crossing detector, and sendscontrol pulsesto the opto-triac, then
the triac become conductive[1*].
The zero-detect signal is taken to pin 2 of the Arduino, an interruptinput. Thiswill
occur at the start and end of the zero-crossingdetector pulse [1*].
Finally, we can control the illumination intensity of the light decease it or increase it as
we need.
This projectis the first step to increase the demand of electric power, the second step
which has been donein the second project by replacing the electrical sourceinto
renewableenergy sourcelike solar energy battery and an electrical switch “IGBT”. In
the second step the PulseWidth Modulation “PWM” techniquewillbe used to dim the
lightening of the LED light
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1.2 Motivations for carrying out theproject :
The energy sourcesin the world aredecreasing rapidly and there is large energy
consumption in street without benefit, so we should find way to reducethe losses.
Controllingthe street lights usingthe dimmingcircuit is very usefulmethod to save and
reducethe power consumption add to this it is a very cheap method.
1.3 Report Organization:
The reportis subdivided into seven chapters which are organized as following:
The first chapter is an introduction shows the essential information regarding the
details and the motivation for the carrying out the project, the second talks about the
standards, constraints and earlier work, the third is literature review, the fourth is
about the street lights types, the fifth includes the methodology; the sixth is about
results and circuit analysis for auto Control Street lights. The seventh is discussion
chapter where the results will be interpreted and compared. Finally the eighth includes
the conclusion and recommendations.
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Chapter 2
Constraints, standards and earlier work
In this project the IEC code has been used, the internationalelectro-technical
commission is a worldwideorganization for standardization comprisingallnational
electro-technical committees (IEC committees). The object of ICE is to promote
international co-operation on all questionsconcerningstandardization in the electric
and electronic fields. To this end and in addition to other activities, IEC publishes
internationalstandards, technical specifications (PAS) and guides(hereafter referred to
as “IEC” publications). Their preparationsis entrusted to technical committees; any IEC
committee interested in the subject dealt with may participate in this preparatory work.
International, governmentalorganizationsliaising with IEC also participate in this
preparation. IEC collaborates closely with the InternationalOrganization for
Standardization (ISO) in accordance with conditionsdetermined by agreement between
the two organizations.
In this project IEC 60027 whichconsists of the letter symbolsto be used in electrical
technology.
IEC 60038 defines a set of standard voltages for use in low voltage and high voltage ac
electricity supply systems.
Earlier work:
One of the earliest recorded dimmers is Granville Woods “SafetyDimmer”;
published before that was liable to cause fires.
Early dimmers were directly controlled through the manual manipulation of large
dimmerpanels. This required all power to come through the lighting control location,
Which could be inconvenient and potentially dangerous for large of high-power
systems,such as those used for stage lighting.
When thyristor dimmers came into use, analog remote control systems (often0-10 v
lighting control systems)became feasible.The wire for the control systems was
much smaller (with low current and lower danger) than the heavy power cables of
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previous lighting systems.Each dimmerhad its own control wires, resulting in a huge
number of wires leaving the lighting control location and running to each individual
dimmer.
Many people attribute the invention of the first commercially viable light dimmer to
Eugene Alessio,an electrical Engineer. In the sixties, Alessio began thinking about
an electronic linear means for adjusting a light level on a single light bulb. Using a
Triac, he built several prototype breadboard circuits to experimentwith this new
concept.To house this novel device,he decided on a 2-inch round device
approximately 2.5 to 3 inches long with one end capable of being screwed into a light
bulb socket and the other end able to receive a light bulb.
Although the device interested Sears and other large department stores,Alessio's
patent did not completelyprotecthis idea. He passed along a working prototype to
the Sears representatives,who took it to Texas Instruments to mass manufacture
the product.
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Chapter 3
Literature review
3.1 Types of lampsused in streetlights
A streetlight, lamppost, streetlamp, light standard, is a raised source of light on the edge
of road or walkway, which is turned on or lit at a certain time every night.
The first lamp was invented around 70,000 BC. A hollow rock, shell or other natural
found object was filled with moss or a similar material that was soaked with animal fat
and ignited. Humans began imitating the natural shapes with manmade pottery,
alabaster, and metal lamps. Wicks were later added to control the rate of burning.
Around the 7th century BC, the Greeks began making terra cotta lamps to replace
handheld torches. The word lamp is derived from the Greek word lampas, meaning
torch.
Early lighting fuels consisted of olive oil, beeswax, fish oil, whale oil, sesame oil, nut oil,
and similar substances. These were the most commonly used fuels until the late 18th
century. However, the ancient Chinese collected natural gas in skins that was used for
illumination.
In the 19th century, most cities in the United States and Europe had streets that were
gaslight. Gas lighting for streets gave way to the gas discharge lights used from 1930 till
now; there are too many types of gas lights:
Low Pressure Sodium (LPS):
LPS is the most efficient streetlight sourceused in street lighting. The lampsproduce
monochromaticorange-yellow light, from lamps which are long and skinny. Drawbacks
of usingLPS lamps includethe color rendering. When the lamp is on, everythingaround
it lookseither orange-yellow, black or shades in between.
Also, as the lamp ages, it uses morewattage, which lighting designers need to account
for.
That increase in wattage does result in little-no lumen depreciation, meaningit the light
outputfrom the lamp stays fairly constant over its life.
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High Pressure Mercury:
It is a negative resistance device. This meansits resistance decreases as the current
through the tube increases, so if the lamp is connected directly to Constant-voltage
sourcelike the power lines, the currentthrough it will increase untilit destroysitself.
Therefore it requires a ballast to limit the currentthrough it. Mercury lamp ballasts are
similar to the ballasts used with florescentlamps.
Metal Halide:
It is very closely related to the mercury lamps. Thebasic lamp is the same as a
mercury lamp, butwith other metallic elements added. Theresult is a good quality
white light. Metal halide has not gained wideacceptance as a sourceof street light. It is
mostly found in parkinglots and inside commercial and industrialbuildings. The light is
moreefficient than mercury vapor, butthe lamp life is shorter. Another problem
incurred with metal halide is "color shift". The color of the light produced by each lamp
varies slightly, which leads to a cluttered effect
High Pressure Sodium (HPS):
The lampsweredeveloped in the early 1970sand aremore energy efficient than
mercury and metalhalide lamps. The lamps give off an amber color, have virtually no
problem with color shift, and last for long periodsof time. The lampsbegin to incur
problemswhen they near the end of their life. Lumen depreciation is a problem with
HPS, though still not as severe as the depreciation seen with Mercury. Thelamps begin
to "cycle," which meansthey turn themselves off and come back on a minutelater. This
problem has been addressed withthe recent introduction of non-cyclingHPS lamps.
Those lampsdiffer in power, output, efficiency, energy useand color rendition. The
followingtable shows the differencesthem.
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Table 3.1: Lamp Type Comparison.
What might be surprisingis to know that the lighting can often representa large
costly energy load. For example high pressuresodium bulbs convertabout 50% of
the energy they consumeinto usable light and are highly efficient choice when it
comes into usable lighting requirementsbut its economically it means that the other
50% arelost on turningin an excited state along with mercury to producelight. But
HPS has a very awesomespecialty which is the change of luminanceaccordingto the
supplied power.[2*]
In this projectwe are going to direct our preciousrevenuestowardssupportingthe
cost of lighting expenses. Wewill be able to control constrain and contain those
expenses so that the resulting savings improvesour incomestatement.
Smart choice to controlstreet lights is the Auto-Diming, which can be doneusingthe
dimmer circuit detailed in the followingchapter. [3*]
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3.2 Hardwareand components:
The controller circuit job is to change the illumination of the street lights according to a
time we set this can be doneby changing the conduction angleof the thyristor as the
time changes which changes the power supplied to the light.
The figure (3.1) show the circuit which we use it in our project:
fig. 3.1 The auto control street light circuit
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The circuit in details :
zero crossing circuit
A zero cross circuit is an electrical circuit that detects the instant when a sine wave, or
the naturalformatof alternating current(AC), is at zero volts in amplitudeand sendsa
signal to its controlled circuit. It is very usefulin preventinghigh-surge currentsfor
protecting resistive loads such as incandescentlampsand heaters and in preventing
high-surge currentsthat generate electromagnetic interferenceto electronic circuits.
The zero cross circuit detects the power linevoltage two times duringthe cycle and
makes surethe instantaneouspower linevoltage is zero before engaging the power
switch. Without the zero cross circuit, the switch could engage at a peak voltage level
that causes an abrupthigh-surge current. Moreover, thezero cross circuit may also
ensurethat the AC load is switched on early enough in the voltage cycle to obtain full
power from the AC supply. [4*]
What do we use for zero crossing circuit?
1. Transformer :
A static electrical device that transfersenergy by inductivecouplingbetween its
windingcircuits. A varyingcurrentin the primary windingcreates a varyingmagnetic
fluxin the transformer’scoreand thus a varyingmagnetic fluxthrough the secondary
winding. This varyingmagnetic fluxinducesa varyingelectromotive force(EMF) or
voltage in the secondary winding. Transformerscan beused to vary relative of circuits
or isolate them or both.
Transformersrangein size from thumbnail-sized used in microphonesto units
weighing hundredsof tonsinterconnecting the power grid. A widerange of transformer
designsare used in electronic and electric power applications. Transformersare
essential for the transmission, distribution and utilization of electrical energy. [5*][6*]
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2. Full-wave rectification
A full-waverectifier convertsthe whole of the inputwaveform to one of constant
polarity (positive or negative) at its output. Full-waverectification converts both
polarities of the inputwaveform to pulsatingDC (direct current), and yieldsa higher
average outputvoltage. Two diodesand a center tapped transformer, or four diodesin
a bridge configuration and any AC source (includinga transformer withoutcenter tap),
are needed. Single semiconductor diodes, doublediodeswith common cathode or
common anode, and four-diodebridges, aremanufactured assingle components. Figure
(3.2)shows the outputof the bridge. [7*]
Fig. 3.2 the output of the bridge.
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3. Optocoupler
An optoisolator, also known as an optical coupler or optocoupler, isa semiconductor
device that allowssignals to be transferred between circuits or systems, while keeping
those circuits or systemselectrically isolated from each other. Optoisolators are used in
a widevariety of communications, control, and monitoringsystems.
In its simplest form, an optoisolator consists of a light-emitting diode(LED), IRED
(infrared-emittingdiode), or laser diode for signal transmission, and a photo sensor for
signal reception. The "transmitter" takes the electrical signal and convertsit into a beam
of modulated visiblelight or infrared (IR). This beam travels across a transparentgap
and is picked up by the "receiver," which convertsthe modulated light or IR back into an
electrical signal. The electrical outputwaveform isidentical to the electrical input
waveform, although the inputand outputamplitudes(signal strengths) often differ. The
optoisolator is enclosed in a single package, and has the appearanceof an integrated
circuit (IC) or a transistor with extra leads. . [8*]
Fig. 3.3 circuit symbol for an optocoupler
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Dimming circuit:
Dimmersare devicesused to vary the brightness of a light. By decreasingor increasing
the RMS voltage and, hence, the meanpower to the lamp, it is possible to vary the intensity
of the light output. Althoughvariable-voltage devicesare used for variouspurposes, the
term dimmer is generally reserved for those intended to controllight output
fromresistive incandescent,halogen, and (morerecently)compactfluorescentlights (CFLs)andlight-
emittingdiodes (LEDs). [9*
]
What we use for Dimming circuit?
1. MOC3021
The MOC3021isoptically isolated triac driver devices. These devicescontain a GaAs
interfid emitting diodeand a light activated silicon bilateral switch, which function like
a triac. This is designed for interfacing between electronic controls and power triacs to
control resistive and inductiveloadsfor 240VAC operations.
The usage of MOC3021:
Triac driver.
Industrialcontrols.
Traffic lights.
Motor control.
Solid state relay.
2. TRIAC
The Triac or bi-directional Thyristor construction is a devicethat can be used to pass or
block currentin either direction. It is therefore classed as an AC power control device. It
is equivalent to two Thyristor in anti-parallel with a common gate electrode. As only
one deviceis required there are cost and space savings.
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The Triac has two main terminals. TE1/ TE2 (power in and load out) and a single gate
connection. The main terminals are connected to both p and n regions since the current
can be conducted in either direction. The gate is similarly connected, since a Triac can
be triggered by both negative and positive pulses.
Fig. 3.4 the triac symbol and a simplified cross section of the device
The ON state voltage/ currentcharacteristics resembles a Thyristor. The Triac static
characteristics show that the deviceacts as a bi-directional switch. The condition where
terminal TE2 is positive with respect to terminal1 is denoted by the term TE2+. If the
Triac is not triggered the low level of leakage currentincreases as the voltage increases
untilthe break over voltage V is reached and then the Triac turnsON. The Triac can be
triggered below V by a pulseto the gate, provided that the currentthrough the device
exceeds the latching currentI before the trigger pulseis removed. TheTriac has a
holding currentvaluebelow which conductancecannot be maintained.
If terminal2 is negative with respect to terminal TE2 the blocking and conducting
conditions are similar to the TE2+ condition, but the polarity is reversed. The Triac can
be triggered in either direction by both negative and positive pulseson the gate. The
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actual valuesof gate trigger currentand holdingcurrentas well as latching currentcan
be slightly differentin the differentoperating quadrantsof the Triac dueto the internal
structureof the device.
Cathode/ Anode voltage ratings
The voltage of the AC mainsis usually regarded as a smooth sine wave. In practice there
is a variety of transients, some occurringregularly and others only occasionally.
Although some transients may be removed by filters, Triacs muststill handlecathode/
anodevoltages in excess of the normalmains voltage level. [10*]
3. Aurdino
The Arduino Uno isa microcontroller board based on the ATmega328 which can be
programmed withthe Arduino software. Ithas 14 digital input/outputpins(of which 6
can be used as PWM outputs), 6 analoginputs, a 16 MHz ceramicresonator, the Arduino
Uno can be powered viathe USB connection or with an external power supply. The
power sourceis selected automatically.
The ATmega328 has32 KB memory (with 0.5 KB used for the boot loader). It also has 2
KB of SRAM and 1 KB of EEPROM (which can be read and written with the EEPROM
library). [11*]
4. loads (high pressuresodium lamp)
High pressuresodium (HPS)lamps, a member of the high intensity discharge (HID)
lamp family, are the most efficient white light sourcecommercially available today. HPS
lampswere developed and introduced asenergy-efficientsourcesfor exterior, security,
and industriallighting applications, and are particularly prevalentin street lighting
applications. Dueto their high efficiency and long life.
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In a high pressuresodium lamp, acompact arc tube contains a mixture of xenon,
sodium and mercury. Thexenon gas which is easily ionized, facilitates striking the arc
when voltage is applied across the electrodes. The heat generated by the arc then
vaporizesthe mercury and sodium. Themercury vapor raises the gas pressureand
operating voltage, and the sodium vapor produceslight when the pressurewithin the
arc tube is sufficient. High pressuresodium lampsare the most efficient artificial white
light source with about 29% of the energy used by the lamp producinglight. [12*]
The second dimmer components:
Figure 3.5 the circuit used in the second dimmer
What are the components usedin this circuit?
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1. IGBT: Insulated-gate bipolar transistor
Is a three-terminal power semiconductor device primarily used as an electronic switch and
in a newer devices is noted for combining high efficiency and fast switching. Itswitches
electric power in many modern appliances.
An IGBTcell is constructed similarly to a n-channelvertical construction power MOSFET
except the negative drain is replaced with a positive collector layer, thus forming a vertical
PNP bipolar junction transistor.
This additional positive region creates a cascadeconnection of a PNP bipolar junction
transistor with the surfacen-channelMOSFET.
IGBT symbol
2. IR2110:
Its an IGBTdriver, used to isolate the lower and higher side of the transistor, it
provides the high peak currentnecessary to charge and dischargethe gate rapidly.
Fastcharging of the gate means decreasing switching losses, i.e turn the
MOSFET/IGBTon or off as fast as possible/feasible. (There are other considerations
for the correctswitching frequency).
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3. Arduino.
4. Load: LED lights
3.3 Theories and circuit analyses
Dimmer theory
What is a dimmer?
A dimmer is a device which is created originally to control the brightness of lamps by
altering the total power delivered to the lamp and thus the brightness.
Figure 3.6 demonstrates a basic type of dimmer (Triac dimmer)
Fig.3.6 Basic type of dimmer
The resistor R is a protective resistor for the triac's gate. The potentiometer Rp along
with the capacitor C controls the time that the triac will be conductive, countingfrom
the zero point of the inputwaveform.
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Operation principles
The Triac dimmer operationprinciple:
The dimmer operation is based on the fact that, duringa fullcycle of an AC waveform,
the thyristor will only allow a partof the waveformeto be delivered to the load (lamp).
Figure 3.7 showswave formeof triac operation.
Fig.3.7 Triac operation
Both waveformsabovecome from the same dimmer. The only differenceis that the
waveform on the left will bright the lamp higher than the waveform on the right. That is
because of the left waveform, the triac on the lift will be conductiveearlier than the triac
shown in the right waveform.
The time that the triac becomes conductiveis symbolized with the Greek letter α
(ALPHA) and is measured in angles from the zero pointof the waveform. Thiszero
pointis the pointthat the voltage is 0 volts, and this happens2 times every one full
period of the wave form. When α becomes smaller, the dimmer becomes conductive
sooner and the lamp is brighter. When α becomes bigger, the triac delaysmoreto
become conductiveand thus the lamb is dimmer.
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A fullwavelength period is 360 degrees(2π). Dueto the fact that duringa fullwave
length the zero cross occurstwice, α can take valuesfrom 0° to 180 degrees(0 - π).
When α = 0°, the full power is delivered to the load and when α = π, no power is
delivered to the load. [13*]
Zero crossing detection
The zero cross detection circuit is the mostcritical partwhen designinga dimmer. This
circuit will watch the inputpower waveform and detectwhen this waveform crosses
the 0 point and becomes 0 volts.
Zero cross detection circuits are mainly used in cases when the dimmersneedsto be
controlled from a micro controller. In that case, the micro-controller needsto know the
zero cross detection point of the waveform, so that it cancalculate the angle offset to
send the trigger pulseto the gate of the triac.
Here is an examplecalculation. Supposethat the AC power oscillates in a 50Hz cycle.
This meansthat each cycle will take 1/50Hz = 20 mSecto be completed. Duringthose
20mSec, the waveform willcross the zero point two times, one at the beginning and one
in the middleof the cycle, that will be after 20/2 = 10mSec.
If we wantthe lamp to be half the way bright, then the microcontroller needsto send a
pulsein the middleof each semi-cycle. Thus, a pulsemustbe sent after 5mSecafter each
time the waveform passesthe zero point. For this to be done, the microcontroller will
watch the zero cross detection circuit (ZCD)for a pulse. When the ZCD send this pulse,
the micro controller will count5 mSec and then will trigger the gate of the triac.
In figure3.8 the circuit will perform aZero CrossDetection circuit. This circuit is very
stable and accurate, and has a controllable pulsewidth. Another great advantageis that
because of the transformer, this circuit has a complete galvanic isolation with the mains
supply so that it makesit completely safe and risk free of destroyingthe microcontroller
dueto power peaks. [13*]
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Fig.3.8 performance of zero crossing detection
Zero cross-dimmer response
In this projectthe transformer gives an AC signal , which will enter the half wave
bridge, then the rectified signal enters the optocoupler which gives pulseat every zero
crossing , this signal then can be used to steer an interruptin the arduino .The outputof
the optocoupler willenter to the arduino and then to the triac to control the lightning.
Principle of operation in the IGBT dimmer
AC dimmer usingIGBTtransistor choppingthe sine waveaccording to PWM output
from Arduino. PWM from theArduino isfast enoughto allow neglect any
synchronization and zero-crossingissuesand simply dim the light to desired luminance
by a single command analogWrite(pin, value).
IGBTis fairly new development, atransistor allowingto controlAC voltage (320Vin
this case) and a power of a rangeof a normalhome lights.
Pulse-Width Modulation (PWM), or Pulse-Duration Modulation (PDM), isa modulation
technique that variesthe width of the pulse, formally the pulseduration based on
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modulator signal information. Althoughthis modulation technique can be used to
encodeinformation for transmission, its main use is to allow the control of the power
supplied to electrical devices, especially to inertial loads.
The average valueof voltage (and current)fed to the load is controlled by turningthe
switch between supply and load on and off at fast pace, the longer the switch is on
compared to the off periodswhich called the duty cycle, the higher the power supplied
to the load is. So changing the duty cycle will change the power supplied to the load.
Fig 3.9 the duty cycle.
Fig 3.10 shows the effect of duty cycle at the average value.
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There are too many typesof switches can be used (E.g BJT, MOSFETand IGBTetc.)
dependingon application. The outputvoltage waveform of an ideal inverter should be
sinusoidal. The voltage waveform of an ideal inverter should be sinusoidal. The voltage
waveforms of practical inverter are however, non-sinusoidaland contain certain
harmonics. Square waveor qusai-square wavevoltage maybe acceptable for low and
medium power application and for high power application low distorted, sinusoidal
waveform arerequired. The outputfrequency of an inverter is determined by the rate at
which the inverters controlcircuitry and consequently, an adjustable frequency AC
outputis readily provided. Theharmonics content of outputvoltage can be minimized
or reduced significantly by switching technique of variable high speed power
semiconductor devices.
The waveform illustrated in Fig 3.11 shows95% duty cycle, which is almost the full
power.
Fig 3.11 (95%) of duty cycle
According to this; the lightening intensity can be varied by changing the duty cycle. When its
100% full power will be delivered to the light and as the duty cycle decreased the power
delivered will be decreased .
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Chapter 4
Methodology
Our work divides into:
Software:
We putthe circuit design of the street light controller madesimulationsand then we
did the programmingpart.
Hardware:
Webrought the circuit componentstogether and connected them.
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Designing the circuitand preparing
the components needed.
Making a simulations for the design
Bringing circuit components
together and connectingthem
Writing the Arduino code
rojectfinishing, designing a smart
street light intensity in cheap way
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Chapter 5
Software works
5.1 Matlab
Weuse matlab to simulate the circuit and obtain initial results.
Figure 5.1 show the simulation circuit for auto street light controlcircuit:
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Figure 5.1 the simulation circuit for auto street light control circuit
Weuse matlab to see the result of the project by buildingthe dimmer circuit also
connect it to pulse generator.
Wechange the fire angle and see the result into the voltage, current and the output
power by using scope.
We controlthe firing angle by change the v reference into the comparator in the pulse
generator.
The below figures show the voltage in differentfiringangle:
1-when v reference =0:
Figure 5.2
2-when v reference =.2:
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Figure 5.3
3-when v reference =.4:
Figure 5.4
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4-when v reference =.7:
Figure 5.5
5-when v reference =.9:
Figure 5.6
Wenotice when the firing angle is increase the voltage at the load decrease.
The function of the current:
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1-when v reference =0:
Figure 5.7
2-when v reference =.2:
Figure 5.8
3-when v reference =.4:
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Figure 5.9
4-when v reference =.7:
Figure 5.10
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5-when v reference =.9:
Figure 5.11
Wecan notice from the above figures that the amplitudeof maximum currentis
decrease when the firing angle decreases.
Accordingto the results above we can concludethe power also decrease when the firing
angel increase.
The below figures show the change of the power:
1-when v reference =0:
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Figure 5.12
2-when v reference =.2:
.
Figure 5.13
3- when v reference =.4:
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Figure 5.14
4-when v reference =.7:
Figure 5.15
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5-when v reference =.9:
Figure 5.16
The IGBT Dimmer simulation
Figure 5.17 show the simulation circuit for IGPT circuit:
Fig.5.17
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Weuse matlab to see the result of the project by buildingthe circuit also connect it to
pulsegenerator .
Wechange the duty cycle and see the resultinto the voltage ,currentand the output
power by using scope.
The below figuresshow the outputvoltage in differentduty cycle:
1- When duty cycle =.75:
Fig.5.18
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1- When duty cycle =.6:
Fig.5.19
1- When duty cycle =.5:
Fig.5.20
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1- When duty cycle =.4:
Fig.5.21
5.2 ArduinoUNO
Weuse Arduino c++ codeto makedimmingto the light power.
In the Triac dimmer:
The conceptthis is to make stepper dimmer. A scale is set to dim valuesto dividethe
half sine AC wave .Then timer has been triggered to interruptevery single step.
The codewill trigger an interrupt256 timesevery time zero cross detected. If the value
of dimmingcorrespondswiththe present step then triac is fired and one step later AC
pin is lowered. The codeis provided in appendixA
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In the IGBT dimmer:
A PWM codehas been written, it gives a pwm signalsupplied to the gate of the IGBT.
The codeis provided in appendixB.
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Chapter 6
Results and analysis
The picoscope and oscilloscope have been used to check the results out after
different components in the circuit:
6.1 The triac dimmer results
The input signal
>>>
Fig.6.1
The rectified signal and The zero crossing signal compared with it
>>>>
Fig.6.2
The arduino out put signal
>>>>
Fig.6.3
The signal at the load
>>>
Fig.6.4
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6.2 The IGBT dimmer results
The inputsignal (at the inverter input): it is the pwm signalcomes from the arduino :
1. when the duty cycleequals to 90%
Fig.6.5
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2. When the duty cycle equals 75% :
Fig.6.6
3. When the duty cycle equals 20%:
Fig.6.7
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Chapter 7
Discussion and economical
7.1 Discussion
comparingthe resultsshows that in the triac dimmer when the firingangle is
changed the outputvoltage will be changed as the alpha increased the output
voltage will be decreased whereas in the IGBT dimmer the outputvoltage will be
changed accordingto the pwm signalat the gate; as the duty cycleincreased the
outputvoltage will be increased. Using oneof those two methods the dimming
can be doneand the wanted light intensity can be controlled either by controlling
the firingangle or duty cycle; this will savethe electrical energy.
7.2 Economical advantage
Table 7.1 the percentage of dimming and power consumption during a day
If there is a 1000 lampsin the city then the cost of street light in onenight:
Power
consumption
Percentage of
dimming
Time of the
day
250 wattNo dimming6-10
175 watt30%10-12
125 watt50%12-3
150 watt40%3-6
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1-withoutdimming: 1800 NIS
2-with dimming: 1305 NIS
The saved money=500 NIS
Chapter 8
Conclusion
As the world is runningoutof fuelgetting this stepper dimmer will saveand help in the
reduction of energy consumption.
Accordingto the results of simulation we can get the proper illumination with suitable
amountof energy supplied. When thefiring angle is changed the voltage and current
will be changed dependently.
AS the firingangle increases the voltage will be decreased which will decrease the
illumination, where the firing angle change dependson the time of day, weset a timer
and according to its valuethe firingangle will be changed.
What if we could usea more efficient way to save energy?
Green electricity is the second choice of saving his planet, which was used in the second
part of our graduation project, where a 12 voltsolar battery in the circuit.
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References
[*1] http://www.rotwang.co.uk/projects/triac.html
[2*] http://trilliumee.com/Services_Page.html
[3*] https://www.echelon.com/applications/street-lighting/
[4*] http://www.wisegeek.com/what-is-a-zero-cross-circuit.htm
[5*] http://en.wikipedia.org/wiki/Transformer
[6*] Electric machines book by D. P. Kothari, I. J. Nagrath
[7*] Fundamentals of Power Electronics by D.P. Muhammad Rashid
[8*] http://www.ustudy.in/node/7519
[9*] http://www.epanorama.net/documents/lights/lightdimmer.html
[10*] http://www.sprags.com/summary.html
[11*] http://arduino.cc/en/Main/arduinoBoardUno
[12*] http://www.lightingassociates.org/i/u/2127806/f/tech_sheets/High_Pressure_Sodium_Lamps.pdf
[13*] http://pcbheaven.com/wikipages/Dimmer_Theory/
https://www.pantechsolutions.net/power-electronics/introduction-of-igbt-based-single-phase-pwm-inverter
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Appendix
AppendixA
#include <TimerOne.h> // Avaiable from http://www.arduino.cc/playground/Code/Timer1
int FREQ=60 ; // 60Hz power in these parts
int AC1_Pin= 9 ;// Output pin (TRIAC triggering)
int AC2_Pin =10; // Output pin (TRIAC triggering)
int AC3_Pin =11 ;// Output pin (TRIAC triggering)
int DimMax = 100; // Max value in dimming scale
int DimMin = 0; // Min value in dimming scale
int volatile Dim1 = 0; // Present dimming value
double halfSineTime = 1000000 / (2 * FREQ);//The Timerone PWM period, 60Hz = 8333.33uS
int rampInterval = halfSineTime/DimMax; // Time of one step
int rampCounter = DimMax; //Down counter with present step
int rampPeriod = 5;// For the fading, time in seconds that takes for the half way-up dimming (the same downwards)
int wait = rampPeriod*1000/DimMax;//Delay between increments of dimming
int buffer = 0.1*DimMax;// allows a safety buffer of steps in which results are dirty
void setup ()
{ //set the mode of the pins…
pinMode(AC1_Pin, OUTPUT);
pinMode(AC2_Pin, OUTPUT);
pinMode(AC3_Pin, OUTPUT);
attachInterrupt(0, light, FALLING ); //Zero-crossing detector
Timer1.initialize(halfSineTime);
Timer1.disablePwm(9);
Timer1.disablePwm(10);
Timer1.disablePwm(11); }
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AppendixB
int led= 5; //LED connectedto digital pin10
void setup()
{
pinMode(led, OUTPUT);
TCCR0B = 0x03;
}
// the loop()method will run continuoslyuntil power is removed.
void loop()
{
//Increase the brightness
for (int value=0;value<=255;value+=10)
{
analogWrite(led,value);
delay(300);
}
delay(200);
//Decrease the brightness
for (int value=255;value>=0;value-=10)
{
analogWrite(led,value);
delay(300);
}
delay(200);
}
