ABSTRACT An inverter is an µelectronic circuit§ circuit§ for converting µdirect current§ current§ (DC) to µalternating current§ current§ (AC). Inverters are used in a wide range of applications, from small µswitched power supplies§ supplies§ for a computer to large µelectric utility§ utility§ applications to transport bulk power. This report contains details of the design and construction of a modern 3000W dc to ac inverter. The system consists of the main inverter inverter stage, the charging unit and the overload protector. These units are further subdivided into different stages. The main inverter performs the basic operation of converting the input DC signal from the battery into an AC signal. It then amplifiers the AC signal by the use of transistor MOSFET drivers and then step-up the signal to the require power (3000W) by the use of step-up transformer. The charging unit contains an automatic switch that transfers the battery from supply to charge when it senses supply from mains. Lastly, the overload protector is a thermal detector that determines the heat generated by the step-up transformer. This heat is directly proportional to the current drown from the transformer and thus to the load. . Chapter one contains an introduction to to inverters, chapter two two contains a review of related literature, chapter three contains the circuit design analysis, chapter four contains the contraction details ,and five contains the summery.
CHAPTER ONE INTRODUCTION 1.1 PREAMBIE Due to toady’s total dependence on electricity and because of frequent Power outage, back up power is becoming a necessity. Emergency back up power system can provide electrical power to critical loads or the whole house during power outages. Emergency power systems are types of systems, which may include lighting generator and other apparatus, to provide back up resources in a crisis or when regular systems fail. They find uses in a wide variety of setting from residential homes to hospitals scientific laboratories and computerized systems. Emergency power system can rely on generators or uninterruptible power supplies. All type of electronic devices requires power supply from electric power for their operation. This source can be either generator or a battery. In our society today, the need for power supply can not be over emphasize, because the provision of good and services could be completely cut off without power supply. For one to fully enjoy the betterment of living in this new dispensation there should be an adequate stable source of power supply. Over the years electricity has been generated through energy conversion from one place to another. Some of these energy sources are, . Solar . Thermal .Wind . Electric generators. They have proved to be quite reliable and efficient but over the years due to inadequate sources of energy to run the engines or a fault in the system its
self poor maintenance, they fail the users at one time or the other. As such the need for standby power supply is essential which brought into existence an alternative means called. INVERTER. An inverter is simply an electronic source of power supply, that that work on the principle principle or save and spend, spend, thus it has a storage unit and a processor with the Dc battery serving as the``backup``for the``backup``for storage, while the electronic circuit could basically be seen as the inverter. An inverter is an electronic circuit for converting direct current (DC) to alternating current (AC). Inverters are used in a wide range of application from small-switched power supply for a computer to large electric utility applications to transport bulk power. It allows the 12 or 24volt (battery) Dc power available in an automobile or from solar panels to supply (AC) power to operate equipment that is normally supplied from a power source. 1.2 STATEMENT OF THE PROBLEM Inverters generally are made to give an AC output. However, most inverters in the market today use oscillators that produce square pulse or rough sine wave. This result in noise in the output, which calls for an inverter with an output that is an approximate sine wave thereby reducing the noise. 1.3 AIMS AND OBJECTIVE The aim of this project is to design and construct a 3KW inverter with little or no noise. This is to be realized by achieving the following specification objectives; -Design and construction of a CD4047 based oscillator circuit. -Implementation of a fine slow charging unit to recharge the battery -Implementation of an automatic switch unit from charge to supply
1.4 METHODOLOGY To achieve the aim of this work, research was undertaking on the net and other source to ascertain the basic operating principle of inverters in general. The block was then developed which reflects the basic units of the desire system. The units are; main inverter is an oscillator, which converts dc to ac, a signal amplifier whose function is to amplify the oscillator output, the driver stage, which further amplifies the signal to drive the primary winding of the step-up transformer. transformer. The transformer step the output AC power power to the require 3000watt output. The charging and switching units are also included.
CHAPTER TWO
LITERATURE REVIEW
2.1
INTRODUCTION
Techno Technolog logica icall advanc advanceme ement nt brough broughtt us into into new era wher where e by the whol whole e worl world d is now now a global obal villa illage ge,, electronic component and appliance are not left behind. So as the need need for for gener enerat atin ing g elec electtrici ricitty throu hrough gh “inver “inverter ter” ” increas increase, e, there there are various various design designs, s, which which have been carried out in the past to achieve this aim. But one thing that needs to be stressed here is that the previous designs have some shortcoming that led to design of this project whose aim is to eliminate these shor sh ortc tcom omin ings gs.. The The past past (pre (previ viou ous) s) desi design gns s will will be review and their shortcoming will be clearly explained in this chapter. 2.2
INVERTER USING 555 TIMER
DC to AC inverter using 555 IC timer is one of the previ previous ous desi design gns. s. In this this proje project ct it prod produc uctt a sq squar uare e wave wave,, but but its its sh shor ortc tcom omin ing g here here is, is, it does does not not have have batter battery y chargi charging ng system system incorp incorporat orated ed in the design design.. The The sq squa uare re wave wave prod produc uced ed by this this sy syst stem em set set the the system to be unsuitable for inductive loads. As seen in the figure below transistors are used for the switching aspect. While the 555 IC timer produces the oscillation pulse
Fig. Fig. 2.1: 2.1:
Current Current diagra diagram m of of an an iinver nverter ter with with 555 555 timer timer
In the output of the visible multivibrator, it’s added to be stable at 50HZ; signal is uttered by transistor TR and TR4 which are arranged as emitter followers to provide curr curren entt gai gain at most ost unit unity y volt voltag age e gain gain.. D and and D2 protect the circuit against induced high voltage strikes. The butters output drives high gain power darlington devi device ces s TR5 and TR6 with with this this tran transi sist stor or,, they they are are concerned with heat sink. With this also the system is found
to
be
functioning
as
desired
except,
the
shor sh ortc tcom omin ing g ther there e are are some some litt little le vari variat atio ion n in the the outpu outputt sign signal al due to temp tempera eratu ture re rise rise,, whic which h could could change the operation point of the transistors. Also the darl arlingt ngton
tran ransistor
used us ed
for
swit witchi hin ng
CJa CJa
not
wit withs hsta tand nd hi hig gh outp output ut curr curren entt. The The desi desig gn of the the diagram is as show in Fig. 2.2.
Fig. 2.2:
Circuit
diagram
of
an
inverter-using
transistor.
2.4
INVERTER USING CD 4047 AND CD 4049
In the projec ojectt is it the CD 4047 with provi ovide the oscillation stage. It produces an oscillating voltage that has
rec rectangul ngula ar
wave aveform orms.
The
desired
outp utput
freq freque uenc ncy y of in inve vert rter er in 50 50HZ HZ,b ,but ut the the osci oscill llat ator or is generating a frequency of 3.27 to 68HZ therefore CD 4049, which is a frequency division stages is employed to obtain 50HZ at the output. It shortcoming have is, the complexity of the circuit and the wave produce by the circuit makes it unstable, below the circuit diagram.
Fig 2.3 circuit diagram of an inverter using CD4047 IC and CD4049 INVERTER USING SG 3524
With an improve diagram, which involve the used of SG 3524 and CMOS MOS CD 4049 which are are also speci ecial integrated circuit. IC SG 3524, which is design for the purpo purpose se of frequ frequenc ency y gener generat atio ion n whil while e buffe bufferr IC CD 4049,
stabilizes
the
frequency.
The
design
is
incorporated with battery charger-section and also over load load prot rotecti ection on sect ection. ion. More More als also
the osci oscill llat atio ion n
produce by this system is a quasi wave. With this, the system is said to be stable, but when the load is introduced that is inductive load, the voltage redu reduce ces s whic which h natu nature re chan change ges s the the quas quasii wave wave to a square wave making the system to be unstable and unreliable. Also with the in corporation of the battery charger section it makes the system to be complex. Below is the diagram.
Fig. Fig. 2.4: 2.4:
Circuit Circuit diagra diagram m of of an an iinver nverter ter using using SG SG 3524 3524..
Apart from the PPC, the MOSFET is also involved in this proje project ct.. The meta metall oxid oxide e semi semico cond nduc ucto torr fiel field d effec effectt transistor (MOSFET) is a switching device. The MOSFET circuit consumes negligible power, its gate terminal is insulated from the chidunel by a layer of silicon dioxide. Th e
layer
of
silicon
dioxide
increase
the
input
impedance of the FCT to an extremely high value is main mainta tain ined ed from from all all valv valves es and and pola polari riti ties es of gate gate.. Source voltage, since the impedance does not depend up on a rever reverse se bias biased ed pp-n n junc juncti tion on.. MOSFE MOSFETS TS have have facts switching and can switch very high currents in a few billionth of a second, and also the drain current of a MOSFET MOSFET decreas decreases es with with increas increase e in temper temperatu ature re and the risk of terminal instability is reduced.
MOSFET MOSFETS S can functio function n as voltag voltage e contro controlle lled d variabl variable e resistor; the gate voltage controls channel resistance. The The pi pic c base based d inver nvertter prod roduced uced pure pure sine sine wave wave however it has the limitation of circuit. Complexity and overa erall
cost.
It
also
poses
one genera nerall
probl oblem
asso associ ciat ated ed was been been prog program ramme med d in the the pic, pic, whic which h controls the overload protection section (battery under volt voltag age e
prot protec ecti tion on))
batt batter ery y
char charge gerr
sect sectio ion n
(ove (overr
voltage protection) and also controls the drive section of the inverter; as shown in fig 2.5 below. Pin RBO of the PIC 16F84A the under voltage protection, when the
battery is at ion, it signal the pilot short, it OH. Pin RBO also also contr control ols s the the over over volta voltage ges s prot protec ecti tion on at 14 14v v it signal the PJC and at RBT the signal is pass to a relay through (via) a resistor and transistor, which short off the system. R. A. 2 and RA3 leds to the MOSFETs. The pic along does all the work, which makes it easier, more reliable and reduces the complexity. The pic provides a quasi wave at a frequency at 50H3. The introduction of inductive leads the wave does not change at all, the still maintain the same wave. Other design with poor storage system charging and supplying timing. THE
INV INVERTER TER
WITH
AUTOMATIC TIC
SWITCHI CHING
OF
BATTERY Thi This s is an in inve vert rter er with with two two batt batter ery y and and auto automa mati tic c swit switch chin ing g betw betwee een n them them.. The The bl bloc ock k di diag agra ram m of the the system is presented below.
µ§
Fig 2.5 Inverter with automatic battery switching The system consists of three basic stages. The main Bat t t er y y inverter 1
stage, the switching unit and the timer. These
units are further subdivided into different stages. The Battery 2
main
inverter
performs
the
basic
operation
of
converting the input DC signal from the battery into an AC signal. It then amplifiers the AC signal by the use of transistor / MOSFET drivers and then step-up the signal to the require power (1000W) by the use of step-up transformer. The timer unit generates electrical pulse to produce an up counting sequence which is displayed by a 7 – segment LED display. Thi This timer seque equenc nce e deter eterm mines nes the supply and charg arging time of the batte atteri ries es..
The The
swit switc chi hing ng
unit unit
perf perfor orms ms
autom utomat atic ic
switching between the batteries at ensures that each battery supply the inverter for batteries. The switching uni nitt
perf erforms rms
auto utomati atic
swit witchi hin ng
between een
the
batte atteri ries es it ensu ensure res s that hat each each batt attery ery su sup ppl ply y the the inverter for approximately 90 minutes and switch over for 90 min charge rge to rep replace it lost energ nergy y. The swit switch ching ing opera operati tion on is been been contr control olle led d by the the sign signal al from the timer unit via the logic unit. This, every 90 minut minutes es swit switch ching ing over over opera operati tion on from from char chargi ging ng to supply and vise vase in performed. 2.5
INVERTER USING PIC 16f84a
Thi This s proj projec ectt prod produce uce a pure pure sine sine wave wave outpu outputt sign signal al unlike all the others explained above. The inverter use the PIC 16F84A as its basic component. PIC which is peripheral. Interface Interface controller, controller, it is different different from integrated integrated circuit (IC) which are used in the previous design. PIC 16+84A which
belongs to micro controller devices. PIC 1684A is an 18 pin 14 bit bit embe embedd dded ed micr micro o featu featurin ring g elec electr troni onica call lly y eras erasab able le programmable read only memory (EEPROM). This program can be erased using ultraviolet light.
Fig 2.6 Simple Simple inverter inverter circuit circuit with an electromechan electromechanical ical switch and with a transistor switch. 2 .6
BASIC INV NVE ERTER DESIGNS: NS:
In one simple inve nverte rter
circuit, DC powers connected to a transformer through the the cent centre re tap tap of the the prim primar ary y wind windin ing. g. A swit switch ch is rapidly rapidly switched back and forth to allow current to flow back back to the the DC sourc source e foll follow owin ing g two two alte alterna rnate te path paths s through one end of the primary winding and then the other. The alternation of the direction of current in the primary winding of the transformer produces alternate current (AC) in the secondary circuit. 2.7 2. 7
The elec electr trom omech echani anica call versio version n of the switc switchin hing g device device includes two stationary contacts and a spring supported moving contact. The spring holds the movable contact against
on e
of
the
stationary
contacts
and
an
electroma omagnet opposite
pulls
stati ationary
the
movable
cont ontact.
The The
conta ntact
to
the
curre urren nt
in
the
electromagnet is interrupted by the action of the switch so that that the switch switch contin continuall ually y switch switching ing rapidl rapidly y back back and forth. This type of electromechanical inverter switch called a vibrator or a buzzer was once used in vacuum tube automo automobil bile e radios radios (refine) (refine).. A simila similarr mechani mechanism sm has been used in door bells, buzzers and tattoo guns. As they they have have become become availa available ble,, transi transisto stors rs and variou various s othe otherr type types s of semi semico cond nduc ucto torr swit switch ches es have have been been incorporated into inverter circuit designs.
2.7 2. 7
INVE INVERT RTER ER OUTP OUTPUT UT WAVE WAVEFO FORM RM The The swit switch ch in the simp simple lest st inve invert rter er desc descri ribe bed d above above produces a square voltage waveforms as opposed to the sinusoidal waveform that is the usual waveform of an AC power supply that is the usual waveform of an AC power
supply.
Using
Fourier
analysis,
periodic
waveforms are represented as the sum of an infinite series of sine waves. The sine wave that has the same freq freque uenc ncy y as the orig origiinal nal wave wavefo form rm is call called ed the the fundamental component.
The The othe otherr sine wave waves s cal called led harm harmo oni nies es,, that hat are are included in the series have frequencies that are integral multiples of the fundamental frequency.
The The qual qualit ity y of the the invert inverter er outp output ut wavef waveform orm can can be expres ressed by us usiing the Fouri urier analys alysiis data to calculate the total harmonic distortion (THD). The total harmonic distortion is the square root of the sum of the squa sq uare res s of the the harm harmon onic ic volta oltage ges s divid ivided ed by the fundamental voltage.
THD
=
2 2
+Vv32 + V42 + + Vn2
……….. (1)
The quality of the output waveform that is needed from asn asn in inve vert rter er depe depend nds s on the char charac actteri erist stiic of the connected load (Ref) some loads media nearly perfect sine sine wave wave volt voltag age e su supp pply ly in orde orderr to work work prop properl erly. y. Other loads may work quite well with a square wave voltage. 2.8
MORE ADVANCE INVERTER DESIGNS
Introduce what you want to discuss
Fig Fig. 2.8 .8::
H-br Hbrid idge ge in inve vert rter er circ circui uitt wit with trans ransfo form rmer er
switches and anti parallel diodes. There are many different power circuit topologies and contro controll strate strategie gies s used used in invert inverter er desig designs. ns. Differe Different nt design approaches are used to address various issues that may be more or less important depending on the way that the inverter is intended to be used.
The The issu issue e of wavef waveform orm qual qualit ity y can can be addr addres esse sed d on many ways. Capacitors and inductors can be used to filter
the
waveform.
If
the
design
include
the
transformer, filtering can be applied to the primary or secondary secondary side of the transformer transformer or to both sides. Low pass ass fil filters ters are are app applied lied to all allow the fund fundam amen enta tall component of the waveform to pass to the output while limiting the passage of the harmonic components. If the invert erter is designed to provi ovide power wer at a fixe fixed d freq requenc ency, a res resonant nant filter can be us used ed.. For an
adjustable frequency inverter, the filter must be turned to a frequency that is above the maximum fundamental frequency.
Since most loads contain inductance, feedback rectifier a para parall llel el di diod odes es are are ofte often n conn connec ecte ted d acro across ss each each semi semico cond nduct uctor or swit switch ch to prov provid ide e a path path to the the peak peak indu in duct ctiv ive e load load curr curren entt when when the the semi semico cond nduc ucto torr is turned off. The antiparallel diodes are somewhat similar to the free wheeling diodes used in AC/DC converter circuits.
Fourier analysis reveals that a waveform, like a square wave that is antisymetrical about the 180 degree point contain only odd harmonics, the 3 rd, 5th, 7th etc. Wavef avefor orm ms that hat have have st step eps s of cert ertain ain widt widths hs and and heights heights eliminate eliminate or “cancel” “cancel” additional harmonics. harmonics. For example, by inserting a zero voltage step between the positive and negative sections of the square wave, all of the the harm harmon onic ics s that that are are di divi visi sibl ble e by thre three e can can be eliminated. That leaves only the 5th, 7th, 11th, 13th etc. the required width of the steps is one third of the period for each of the positive and negative negative voltage voltage steps and one switch switch of the period for each of the zero voltage steps.
Changing the square wave as described above is an example of pulse width modulation (PWM). Modulating or regulating the width of a square wave pulse is often used as a method of regulating or adjusting inverters output voltage. When voltage control is not required, a fixed pulse width can be selected to reduce or eliminate selected selected harmonics. harmonics. Harmonic Harmonic elimination elimination techniques techniques are generally applied to the lowest harmonics filtering is more ore effe effec ctive tive at hi high gh freq freque uenc ncie ies s than han at how how freq freque uenc ncie ies. s. Mult Multip iple le puls pulse e widt width h or carr carrie ierr base based d (PWM) (PWM) contro controll sc schem heme’s e’s produc produce e wavefor waveforms ms that that are com compose posed d of many any narr narrow ow pul uls ses. es. The The freq freque uenc ncy y rep represe resent nted ed by the num number ber of narr narrow ow pul uls ses per seco second nd is call called ed the the swit switch chin ing g freq freque uenc ncy y or carr carrie ierr frequency. These control scheme’s are often used in vari variab able le freque frequenc ncy y moto motorr cont control rol inver inverte ters rs beca becaus use e they allow a wide range of output voltage and frequency adjustment while also improving the quality of the waveform.
Mul Multil tilevel evel
inve in vert rter ers s
pro provide vide
anoth nother er
app approac roach h
to
harmonic cancellation. Multilevel inverters provide an output waveform that exhibits multiple steps at several voltage levels. For example it is possible to produce a more sinusoidal wave by having split rail direct current inputs at two voltages, or positive and negative inputs
with with a cent centra rall grou ground nd..
By conne connect ctin ing g the the in inve vert rter er
output terminals in sequence between the positive rail and and grou ground nd,, the the posi positi tive ve rail rail and and nega negati tive ve rail rail,, the the ground rail and the negative, then both to the ground rail, a stepped waveform is generated at the inverter output. This is an example of three level inverter; the two voltages are ground.
Fig Fig. 2.9 .9::
3 PH PHAS ASE E IVNE IVNERT RTER ER WITH WITH WYE CONN CONNE ECTED CTED
LOAD
Three phase inverter are used for variable frequency drive applications applications and for high power applications applications such as HV HVDC DC powe powerr trans ransmi miss ssio ion. n. A basic asic thre three e phas phase e inve in vert rter er as sh show ow in Fig Fig 2. 2.4 4 cons consis ists ts of thre three e sing single le phase inverter switches each connected to one of the thre hree load termi rminals als. For For the most ost basi asic control
scheme,
the
operation
of
th e
three
witches
is
coor coordi dina nate ted d so that that one swit switch ch oper operat ates es at each each 60 degree point f the fundamental output waveform. This creates a line to line output wave form that has size steps. The six step waveform has a zero voltage step betw betwee een n the the posi positi tive ve and and nega negati tive ve sect sectio ions ns of the the square wave such that the harmonics that are multiples of thre three e are are elim elimin inat ated ed as desc descri ribe bed d abov above. e. When When carrier based PWM techniques are applied to six step waveforms, waveforms, the basic overall shape, or envelope, of the waveform is retained so that the third harmonic and its multiples are cancelled.
3.3 CIRCUIT CIRCUIT DESIGN DESIGN ANALYS ANALYSIS IS 3.3.1 DESIGN SPECIFICATION Output power
=
3000W
Frequency
=
50Hz
Input voltage
=
12Vdc
Output voltage
=
220Vac
3.3. 3.3.22 POWE POWER R SUP SUPPL PLY Y / CHAR CHARGE GER R The switching unit, timer, thermal sensor/indicator, and the charging unit, require a wellfiltered and regulated DC power to drive their individual components.
The power supply is made up of step down transformer, which steps the input 220Vac down to 15Vac. The bridge rectifier converts the AC signal to DC of the same voltage level. The rectifier consists of diodes D1-D4. The circuit arrangement is such that at any point in time, two diodes are conducting while the other two are at cut-off. The filter capacity removes the AC ripples from the DC voltage. The IC regulator regulates the DC signal to give a steady, well-regulated dc output voltage. Fig. 3.2 power supply circuit Transformer Rating
Required output voltage (V2) =15V Input voltage (V1) =220v Primary turns (N1) =300 Secondary turns (N2) =x N2 =N1V2/V1 =300(15) 220 =20 turns. Transformer output current = 2V Output power = 15V x 2A = 30W Rectifier
µ§ Fig.3.3 Rectifier circuit As explained earlier, The Bridge rectifier is a circuit, which converts an ac voltage to dc voltage using both half cycles of the input ac voltage. The Bridge rectifier circuit is shown in the figure. The circuit has four diodes connected to form a bridge. The ac input voltage is applied to the diagonally opposite ends of the bridge. The load resistance is connected between the other two ends of the bridge. For the positive half cycle of the input ac voltage, diodes D1 and D3 conduct, whereas diodes D2 and D4 remain in the OFF state. The conducting diodes will be in series with the load resistance R L and hence the load current flows through R L.L. For the negative half cycle of the input ac voltage, diodes D2 and D4 conduct whereas, D1 and D3 remain OFF. The conducting diodes D2 and D4 will be in series with the load resistance R L and hence the current flows through R L in the same direction as in the previous half cycle. Thus a bi-directional wave is converted into a unidirectional wave. Peak Inverse Voltage
Peak inverse voltage represents the maximum voltage that the non- conducting diode must withstand. At the instance the secondary voltage reaches its positive peak value, Vm the diodes D1 and D3 are conducting, where as D2 and D4 are reverse biased and are non-conducting. The conducting diodes D1 and D3 have almost zero resistance. Thus the
entire voltage V m appears across the load resistor R R L. The reverse voltage across the nonconducting diodes D2 (D4) is also V m. Thus for a Bridge rectifier the peak inverse voltage is given by µ § Since transformer output voltage = 15V V M M = 15V Diode current rating = 2 x transformer current = 2 x 2A = 4A
Rectifier diode to match this rating = IN4007 (Obtained from diode transistor specification book).
The output from the rectifier is given as – Without capacitor.
With capacitor.
VAC = 1.1x (VDC = 2)
VAC = 0.8 (VDC +2)
= 1.1 X (12X2)
= 0.8 (14)
1.1 X 14
= 11.2v
= 15.4v
This shows the need of the capacitor. Hence output current IDC = 1.8 X IDV IDV = 1.8XO.5A 0.9A
Power output after fliter stage = 0.9 x 11.2 = 10.0w = 10w
Calculating for the capacitor C = (Il x t )/Vrip) x10 6 When Il = 0.9 T = 1/2x60 = 0.008333 (for 60H Z SUPPLY)
Vrip = Vrms x Ripple Vp-p = 0.325v+ 2.828v = 0.92
C (uf) (0.9 x 0.00833/0.92) x 106 =0.00814891 x 106 = 1000 uf (standard value)
Capacitor voltage rating should be at least 1.5 x VDA = 1.5X11.2 = 16.8V =16V (standard value) C = 1000uf 16V.
Ripple Factor
The ripple factor for the Full Wave Rectifier is given by µ§ The average voltage or the dc voltage available across the load resistance is µ§ µ§ µ§ RMS value of the voltage at the load resistance is µ§ µ§
Efficiency
Efficiency, is the ratio of the dc output power to ac input power µ§ µ§ The maximum efficiency of a Full Wave Rectifier is 81.2%.
THERMAL SENSING AND INDICATION UNIT This unit converts the electrical signal from the heat sensor (thermistor) into an electrical signal. The basic component of the circuit is LM 741 operational amplifier configured in the comparator mode.
Figure 3.2 Operational Amplifier
Where
V+ is non-inverting input pin 3
V- is inverting input
pin 2
Vout is output
pin 6
Vst is positive power supply pin 7 Vs- is negative power supply pin 4 The general operational amplifier has two inputs and one output, the output voltage is a multiple of the difference between the two inputs (one can be made floating).
Figure 3.3. 3.3. unit of comparator circuit. R1 sets the reference (non-inverting) (non-inverting) voltage Vout = t (Vin – Vref), Where (t is the open-loop gain of the operational amplifier. In this comparator mode, Vout is HIIGH if the incoming voltage is equal to or above Vref. Otherwise, the output is LOW. Since R1 is variable in other to set different reference voltage levels, its value is not critical. Thus picking a 50K ohms resistor, R1 could be seen as cons consis isti ting ng of two two fixe fixedd resi resist stor orss and and at 5o% 5o% vari variat atio ion, n, Ra=2 Ra=25K 5K and and Rb=25K. V = supply voltage x R a/R a+R b
V= 9v x 25000/ 25000+25000
v = 9v x (25000/50000 ohms) V = 9v x 0.5 ohms V = 4.5v µ§
Vin is determine by the resistance of the thermistor. It varies with the magnitude of heat from the transformer. The resistance can vary from approximately 200Kohms to about 10 Ohms. In between, different voltages are produce as a result of the variation in resistance. The output from the opamp is then fed to the transistor which drives the buzzer.
THE STEP-UP TRANSFORMER DESIGN
Determination of number of turns is calculated using 3000W In order to achieve a good number of turns flux density of 1.531tesla was assume and the following calculation was made A = (√P/5.58 Where A = Area in square meter (M2), P = power in watts (W) = 3000W and 5.58 is a constant A = √3000/5.58 = 9.8158CM2 = 9.8158 x 10-4M2
E = 4.44 F Φm N and Φm = BmxA Where E = emf of transformer in volt (V), F = frequency in Hertz (H Z) = 50Hz, Φm = flux in Weber (w), B m = flux density in tesla = 1.531tesla, A = Area in square meter (M2) = 9.8158 x 10-4M2 and N = number of turns Φm = 1.531 x 9.8158 x 10-4 = 1.5028 x 10-3w = 1.5028mw Determination of number of turns on primary side, emf per turn E1. E1 = 4.44 x F x Φm = 4.44 x 50 x 1.5028 x 10-3 = 0.3336 V/turn Primary turn N1 N1 = V1/E1 = 12/0.3336 = 35.9689turns ≈ 36turns Secondary turns N2 (N1/N2) = (V1/V2) N2 = (N1 x V2)/V1 = ( 36 x 220) / 12 = 660turns Determination of wire diameter
A = I/D and d = √((A x 4)/Π) Where A = cross-sectional cross-sectional area in square millimete millimeters rs (mm2), D = current density = constant = 3.08A/mm2, I = current in Amperes (A), d = diameter in millimeters (mm) and Π = 3.142 Primary current I1 I1 = 3000/12 = 250A A1 = I1/D = 250/3.08 =
81.1688mm2
d1 = √((81.1688 x 4) / 3.142) = 10.1653 mm
Secondary current I2 I2 = 3000/220 = 13.6364A A2 = I2/D = 13.6364/3.08 = 4.4274mm2 d2 = √((4.4274 x 4) / 3.142) = 2.3741mm
3.3 CIRCUIT DIAGRAM OF THE SYSTEM CIRCUIT A CIRCUIT DIAGRAM OF A MORDEN 3000W DC-AC INVERTER
CIRCUIT DIAGRAM OF A 3KW INVERTER
3.4 COMPONENT REVIEW This unit reviews some of the components used in this circuit design. 3.4.1 INTEGRATED CIRCUIT A monolithic integrated circuit (also known as IC, microcircuit, microchip, silicon chip, or chip) is a miniaturized µelectronic circuit§ circuit§ (consisting mainly of µ of µsemiconductor devices§, devices§, as well as µ passive components§) components§) that has been manufactured in the surface of a thin substrate of µ of µsemiconductor § material. A µhybrid integrated circuit§ circuit § is a miniaturized electronic circuit constructed of individual semiconductor devices, as well as passive components, bonded to a substrate or circuit board. Integrated circuits were made possible by experimental discoveries which showed that µsemiconductor devices§ devices§ could perform the functions of µvacuum tubes§, tubes§, and by mid-20th-century technology advancements in µsemiconductor device fabrication§. fabrication §. The integration of large numbers of
tiny µtransistors§ transistors§ into a small chip was an enormous improvement over the manual assembly of circuits using discrete µelectronic components§. components§. The integrated circuit's µmass production§ production§ capability, reliability, and building block approach to circuit design ensured the rapid adoption of standardized ICs in place of designs using discrete transistors. There are two main advantages of ICs over discrete circuits: cost and performance. Cost is low because the chips, with all their components, are printed as a unit by µ photolithography§ photolithography§ and not constructed a transistor at a time. Performance is high since the components switch quickly and consume little power, because the components are small and close together. As of 2006, chip areas range from a few square µmm§ mm§ to around 350 µmm§ mm§2, with up to 1 million µtransistors§ transistors§ per µ per µmm§ mm§2. Advances in integrated circuits Among the most advanced integrated circuits are the µmicroprocessors§ microprocessors§ or "cores", which control everything from µcomputers§ computers§ to µcellular phones§ phones§ to digital µmicrowave ovens§. ovens§. Digital µmemory chips§ chips§ and µASICs§ ASICs§ are examples of other families of integrated circuits that are important to the modern µinformation society§. society §. While cost of designing and developing a complex integrated circuit is quite high, when spread across typically millions of production units the individual IC cost is minimized. The performance of ICs is high because the small size allows short traces which in turn allows low µ power § logic (such as µCMOS§) CMOS§) to be used at fast switching speeds. ICs have consistently migrated to smaller feature sizes over the years, allowing more circuitry to be packed on each chip. This increased capacity per unit area can be used to decrease cost and/or increase functionality—see functionality—see µMoore's law§ law§ which, in its modern interpretation, states that the number of transistors in an integrated circuit doubles every two years. In general, as the feature size shrinks, almost everything improves—the improves—the cost per unit and the switching power consumption go down, and the speed goes up. However, ICs with µnanometer §-scale §-scale devices are not without their problems, principal among which is leakage current (see µsubthreshold leakage§ leakage§ and µMOSFET§ MOSFET§ for a discussion of this), although these problems are not insurmountable and will likely be solved or at least ameliorated by the introduction of µ of µhigh-k dielectrics§. dielectrics §. Since these speed and power consumption gains are apparent to the end user, there is fierce competition among the manufacturers to use finer geometries. This process, and the expected progress over the next few years, is well described by the µInternational Technology Roadmap for Semiconductors Semiconductors§§ (ITRS). Classification
Integrated circuits can be classified into µanalog§, analog§, µdigital§ digital§ and µmixed signal§ signal§ (both analog and digital on the same chip). Digital integrated circuits can contain anything from a few thousand to millions of µ of µlogic gates§, gates§, µflip-flops§, flip-flops §, µmultiplexers§, multiplexers§, and other circuits in a few square millimeters. The small size of these circuits allows high speed, low power dissipation, and reduced manufacturing cost compared with board-level integration. These digital ICs, typically µmicroprocessors§, microprocessors§, µDSPs§, DSPs§, and micro controllers work using binary mathematics to process "one" and "zero" signals. Analog ICs, such as sensors, power management circuits, and µoperational amplifiers§, amplifiers§, work by processing continuous signals. They perform functions like µamplification§, amplification§, µactive filtering§, filtering§, µdemodulation§, demodulation§, µmixing§, mixing§, etc. Analog ICs ease the burden on circuit designers by having expertly designed analog circuits available instead of designing a difficult analog circuit from scratch. ICs can also combine analog and digital circuits on a single chip to create functions such as µA/D converters§ converters§ and µD/A converters§. converters§. Such circuits offer smaller size and lower cost, but must carefully account for signal interference (see µsignal integrity§). integrity§). Packaging
The earliest integrated circuits were packaged in ceramic flat packs, which continued to be used by the military for their reliability and small size for many years. Commercial circuit packaging quickly moved to the µdual inline package§ package§ (DIP), first in ceramic and later in plastic. In the 1980s pin counts of VLSI circuits exceeded the practical limit for DIP packaging, leading to µ pin grid array§ array § (PGA) and µleadless chip carrier § (LCC) packages. µSurface mount§ mount § packaging appeared in the early 1980s and became popular in the late 1980s, using finer lead pitch with leads formed as either gull-wing or J-lead, as exemplified by µSmall-Outline Integrated Circuit§. Circuit§. A carrier which occupies an area about 30 – 50% less than an equivalent µDIP§, DIP§, with a typical thickness that is 70% less. This package has "gull wing" leads protruding from the two long sides and a lead spacing of 0.050 inches. µSmall-Outline Integrated Circuit§ Circuit § (SOIC) and µPLCC§ PLCC§ packages. In the late 1990s, µPQFP§ PQFP§ and µTSOP§ TSOP§ packages became the most common for high pin count devices, though PGA packages are still often used for highend µmicroprocessors§. microprocessors§. Intel and AMD are currently transitioning from PGA packages on high-end microprocessors to µland grid array§ array§ (LGA) packages.
µBall grid array§ array § (BGA) packages have existed since the 1970s. µFlip-chip Ball Grid Array§ Array§ packages, which allow for much higher pin count than other package types, were developed in the 1990s. In an FCBGA package the die is mounted upside-down (flipped) and connects to the package balls via a package substrate that is similar to a printed-circuit board rather than by wires. FCBGA packages allow an array of input-output signals (called Area-I/O) to be distributed over the entire die rather than being confined to the die periphery. Traces out of the die, through the package, and into the µ printed circuit board§ board§ have very different electrical properties, compared to on-chip signals. They require special design techniques and need much more electric power than signals confined to the chip itself. When multiple dies are put in one package, it is called SiP, for µSystem for µSystem In Package§. Package§. When multiple dies are combined on a small substrate, often ceramic, it's called a MCM, or µ or µMulti-Chip Module§. Module§. The boundary between a big MCM and a small printed circuit board is sometimes fuzzy. 3.4.2 DIODE In µelectronics§, electronics§, a diode is a µcomponent§ component§ that restricts the direction of flow of µ of µcharge carriers§. carriers§. Essentially, it allows an µelectric current§ current§ to flow in one direction, but blocks it in the opposite direction. Thus, the diode can be thought of as an electronic version of a µcheck valve§. valve§. Circuits that require current flow in only one direction typically include one or more diodes in the circuit design. Early diodes included µ"cat's whisker" crystals§ crystals§ and µvacuum tube§ tube§ devices (called µthermionic valves§ valves§ in µBritish English§ English§ µDialect§). Dialect§). Today the most common diodes are made from µsemiconductor § materials such as µsilicon§ silicon§ or µ or µgermanium§. germanium§. Semiconductor diodes
µµ §§ §§ µµ §§ §§ Diode schematic symbol. Conventional current can flow from the anode to the cathode, but not the other way around. Most modern diodes are based on µsemiconductor § µ p-n junctions§. junctions §. In a pn diode, µconventional current§ current § can flow from the p-type side (the µanode§) anode§) to the n-type side (the µcathode§), cathode§), but cannot flow in the opposite direction. Another type of semiconductor diode, the µSchottky diode§, diode§, is formed from the contact between a metal and a semiconductor rather than by a p-n junction. A semiconductor diode's µcurrent-voltage, or I-V, characteristic§ characteristic § curve is ascribed to the behavior of the so-called µdepletion layer § or µdepletion or µdepletion
zone§ zone§ which exists at the µ p-n junction§ junction § between the differing semiconductors. When a p-n junction is first created, conduction band (mobile) electrons from the N-doped region diffuse into the P-doped region where there is a large population of holes (places for electrons in which no electron is present) with which the electrons "recombine". When a mobile electron recombines with a hole, the hole vanishes and the electron is no longer mobile. Thus, two charge carriers have vanished. The region around the p-n junction becomes depleted of µ of µcharge carriers§ carriers§ and thus behaves as an µinsulator §. §. However, the µdepletion width§ width§ cannot grow without limit. For each electron-hole pair that recombines, a positively-charged dopant ion is left behind in the N-doped region, and a negatively charged dopant ion is left behind in the P-doped region. As recombination proceeds and more ions are created, an increasing electric field develops through the depletion zone which acts to slow and then finally stop recombination. At this point, there is a 'built-in' potential across the depletion zone. If an external voltage is placed across the diode with the same polarity as the built-in potential, the depletion zone continues to act as an insulator preventing a significant electric current. This is the µreverse bias§ bias§ phenomenon. However, if the polarity of the external voltage opposes the built-in potential, recombination can once again proceed resulting in substantial electric current through the p-n junction. For silicon diodes, the built-in potential is approximately 0.6 V. Thus, if an external current is passed through the diode, about 0.6 V will be developed across the diode such that the P-doped region is positive with respect to the N-doped region and the diode is said to be 'turned on' as it has a µforward bias§. bias§. µµ §§ §§ I-V characteristics of a P-N junction diode (not to scale). A diode's I-V characteristic can be approximated by two regions of operation. Below a certain difference in potential between the two leads, the depletion layer has significant width, and the diode can be thought of as an open (non-conductive) circuit. As the potential difference is increased, at some stage the diode will become conductive and allow charges to flow, at which point it can be thought of as a connection with zero (or at least very low) resistance. More precisely, the µtransfer function§ function§ is µlogarithmic§, logarithmic§, but so sharp that it looks like a corner on a zoomed-out graph (see also µsignal processing§). processing§). In a normal silicon diode at rated currents, the voltage drop across a conducting diode is approximately 0.6 to 0.7 µvolts§. volts§. The value is different for other diode types - µSchottky diodes§ diodes§ can be as low as 0.2 V and µlight-
emitting diodes§ diodes§ (LEDs) can be 1.4 V or more (Blue LEDs can be up to 4.0 V). Referring to the I-V characteristics image, in the reverse bias region for a normal P-N rectifier diode, the current through the device is very low (in the µA range) for all reverse voltages up to a point called the peak-inversevoltage (PIV). Beyond this point a process called reverse µ breakdown§ breakdown§ occurs which causes the device to be damaged along with a large increase in current. For special purpose diodes like the µavalanche§ avalanche§ or µ or µzener diodes§, diodes§, the concept of PIV is not applicable since they have a deliberate breakdown beyond a known reverse current such that the reverse voltage is "clamped" to a known value (called the zener voltage or µ or µ breakdown voltage§). voltage §). These devices however have a maximum limit to the current and power in the zener or avalanche region. Types of semiconductor diode
µµ §§ §§µµ §§ §§µµ §§ §§µµ §§Diode §§Diodeµ µZener Diode§ Diode§µSchottky Diode§ Diode§µTunnel Diode§ Diode§µµ §§ §§µµ §§ §§µµ §§ §§µµ §§ §§µLight-emitting diode§ diode§µPhotodiode§ Photodiode§µVaricap§ Varicap§µSCR §Some §Some diode symbols 3.4 3.4.3 RES ESIISTOR TOR A resistor is a two-terminal µelectrical§ electrical§ or µ or µelectronic§ electronic§ component that resists an µelectric current§ current§ by producing a voltage drop between its terminals in accordance with µOhm's law§: law§: µ §The µelectrical resistance§ resistance§ is equal to the µvoltage§ voltage§ drop across the resistor divided by the current through the resistor. Resistors are used as part of µ of µelectrical networks§ networks§ and electronic circuits. Calculations Ohm's law
The relationship between voltage, current, and resistance through a metal wire, and some other materials, is given by a simple equation called µOhm's Law§: Law§: µ§ where V (or U in some languages) is the voltage (or potential difference) across the wire in µvolts§, volts§, I is the current through the wire in µamperes§, amperes§, and R, in µohms§, ohms§, is a constant called the resistance—in fact this is only a simplification of the original Ohm's law (see the article on that law for further details). Materials that obey this law over a certain voltage or current
range are said to be ohmic over that range. An ideal resistor obeys the law across all frequencies and amplitudes of voltage or current. µSuperconducting§ µSuperconducting§ materials at very low temperatures have zero resistance. Insulators (such as µair §, §, µdiamond§, diamond§, or other non-conducting materials) may have extremely high (but not infinite) resistance, but break down and admit a larger flow of current under sufficiently high voltage. Power dissipation The power dissipated by a resistor is the voltage across the resistor multiplied by the current through the resistor: µ§ All three equations are equivalent. The first is derived from µJoule's law§, law§, and other two are derived from that by Ohm's Law. The total amount of heat energy released is the integral of the power over time: µ§ If the average power dissipated exceeds the power rating of the resistor, then the resistor will first depart from its nominal resistance, and will then be destroyed by overheating. Series and parallel circuits
Resistors in a µ parallel§ parallel§ configuration each have the same potential difference (voltage). To find their total equivalent resistance (R eq): µµ §§ §§ µ§ The parallel property can be represented in equations by two vertical lines "||" (as in geometry) to simplify equations. For two resistors, µ§ The current through resistors in µseries§ series§ stays the same, but the voltage across each resistor can be different. The sum of the potential differences (voltage) is equal to the total voltage. To find their total resistance: µµ §§ §§ µ§ A resistor network that is a combination of parallel and series can sometimes be broken up into smaller parts that are either one or the other. For instance, µµ §§ §§ µ§
3.4.4 TRANSISTOR
A transistor is a µsemiconductor device§, device §, commonly used as an amplifier or an electrically controlled switch. The transistor is the fundamental building block of the µcircuitry§ circuitry§ that governs the operation of µ of µcomputers§, computers§, µcellular phones§, phones§, and all other modern µelectronics§. electronics§. Because of its fast response and accuracy, the transistor may be used in a wide variety of µ of µdigital§ digital§ and µanalog§ analog§ functions, including µamplification§, amplification§, µswitching§, switching§, µvoltage regulation§, regulation§, signal µmodulation§, modulation§, and µoscillators§. oscillators§. Transistors may be packaged individually or as part of an µintegrated circuit§ circuit§ chip, which may hold millions of transistors in a very small area. Modern transistors are divided into two main categories: µ bipolar junction transistors§ transistors§ (BJTs) and µfield effect transistors§ transistors § (FETs). Application of current in BJTs and voltage in FETs between the input and common terminals increases the µconductivity§ conductivity§ between the common and output terminals, thereby controlling current flow between them. The transistor characteristics depend on their type. See µTransistor models§. models§. The term "transistor" originally referred to the µ point contact§ contact § type, but these only saw very limited commercial application, being replaced by the much more practical µ bipolar junction§ junction § types in the early 1950s. Ironically both the term "transistor" itself and the µschematic symbol§ symbol§ most widely used for it today are the ones that specifically referred to these long-obsolete devices.µ[1]§ For a short time in the early 1960s, some manufacturers and publishers of electronics magazines started to replace these with symbols that more accurately depicted the different construction of the bipolar transistor, but this idea was soon abandoned. In µanalog circuits§, circuits§, transistors are used in µamplifiers§, amplifiers§, (direct current amplifiers, audio amplifiers, radio frequency amplifiers), and linear µregulated power supplies§. supplies §. Transistors are also used in µdigital circuits§ circuits§ where they function as electronic switches, but rarely as discrete devices, almost always being incorporated in monolithic µIntegrated Circuits§. Circuits§. Digital circuits include µlogic gates§, gates§, µrandom access memory§ memory§ (RAM), µmicroprocessors§, microprocessors§, and µdigital signal processors§ processors § (DSPs). Advantages of transistors over vacuum tubes Before the development of transistors, µvacuum tubes§ tubes§ (or in the UK thermionic valves or just valves) were the main active components in electronic equipment. The key advantages that have allowed transistors to replace their vacuum tube predecessors in most applications are: Smaller size and lighter (despite continuing miniaturization of vacuum tubes) Highly automated manufacture Lower cost (in volume production) •
•
•
Lower possible operating voltages (but vacuum tubes can operate at higher voltages) No warm-up period (most vacuum tubes need 10 to 60 seconds to function correctly) Lower power dissipation (no heater power, very low saturation voltage) Higher reliability and greater physical ruggedness (although vacuum tubes are electrically more rugged, and are much more resistant to µnuclear electromagnetic pulses§ pulses § and µelectrostatic discharge§) discharge§) Much longer life (vacuum tube cathodes are eventually exhausted and the vacuum can become contaminated) Complementary devices available (allowing circuits with complementary-symmetry: complementary-symmetry: vacuum tubes with a polarity equivalent to PNP BJTs or P type FETs are not available) Ability to control large currents (power transistors are available to control hundreds of amperes, vacuum tubes to control even one ampere are large and costly) Much less µmicrophonic§ microphonic§ (vibration can modulate vacuum tube characteristics, though this may contribute to the sound of µ of µguitar amplifiers§) amplifiers§) Types µµ §§PNP §§PNPµ µµ §§P-channel §§P-channelµ µµ §§NPN §§NPNµ µµ §§N-channelBJTJFETBJT §§N-channelBJTJFETBJT and JFET symbols Transistors are categorized by: Semiconductor material: germanium, silicon, gallium arsenide, silicon carbide Structure: µBJT§, BJT§, µJFET§, JFET§, IGFET (µ (µMOSFET§), MOSFET§), µIGBT§, IGBT§, "other types" Polarity: µ NPN§, NPN§, µPNP§ PNP§ (BJTs); N-channel, P-channel (FETs) Maximum power rating: low, medium, high Maximum operating frequency: low, medium, high, µradio frequency§ frequency§ (RF), µmicrowave§ microwave§ (The maximum effective frequency of a transistor is denoted by the term f T, an abbreviation for "frequency of transition". The frequency of transition is the frequency at which the transistor yields unity gain). Application: switch, general purpose, audio, high voltage, super-beta, matched pair Physical packaging: µthrough hole§ hole§ metal, through hole plastic, µsurface mount§, mount§, ball grid array, power modules •
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Thus, a particular transistor may be described as: silicon, surface mount, BJT, NPN, low power, high frequency switch. Usage In the early days of transistor circuit design, the µ bipolar junction transistor §, §, or BJT, was the most commonly used transistor. Even after MOSFETs became available, the BJT remained the transistor of choice for digital and analog circuits because of their ease of manufacture and speed. However, desirable properties of MOSFETs, such as their utility in low power devices, have made them the ubiquitous choice for use in digital circuits and a very common choice for use in analog circuits.
CHAPTER FOUR 4.0
CONSTRUCTION
This chapter contains the construction work details. It also contains the list of tools used in the construction work and the testing and result analysis.
4.1
CIRCUIT CON CONSTRUTION
The circuit board consists of the vero board and all other components mounted on it. In its construction, the vero board was cleaned with an iron brush to remove dirt from its surface which might affect soldering quality. Subsequently, following the circuit diagram, the components were mounted on the board one after the other and soldered. The IC was not directly soldered to the board but was mounted on an IC socket. This is to prevent
heat heat damage damage and for ease of replac replaceme ement. nt. Units Units like the power switch switch,, display etc were connected to the board via flexible wires. In the soldering process, care was taken to ensure that the soldered joints have good mechanical and electrical contact. Also great care was taken to ensure that the components were not damage from excess heat from the soldering soldering iron. iron. The following following procedur procedures es were followed followed in the soldering soldering process. - A 40W 40W pencil pencil type type sold solderi ering ng iron iron was was used. used. - A good good qualit qualityy rosi rosin-c n-core ore solder solder was used. used. - For For the iron iron to prope properly rly condu conduct ct heat, heat, the the solderi soldering ng tip tip was well well tinned tinned (coated with a tin layer of solder). To keep the tip clean, it was wiped from time to time on a damp spurge or cloth. - All All comp compon onen entt lead lead and coppe copperr fort fort pads pads were were clean cleaned ed and free free of oxidation oxidation at the time of solderin solderingg by lightly brushing brushing them them with steel wool. - Whil Whilee sold solder erin ingg and and unso unsold lder erin ing, g, a safe safety ty glass glass was used used to avoid avoid eye injury due to flying particle of hot solder. - The top top of the soldering soldering iron was firml firmlyy was was placed placed again against st the the wire wire lead lead and copper pad to heat the connection connection to be soldered. soldered.
Before soldering semiconductor components such as transistors, diode etc. the lead near semi conductor conductor was held with needle nose pliers or tweezers to prevent the heat from the soldering iron from getting to into the component. - Soldering Soldering flux is appli applied ed to to the the conne connection ction as itit is is been been heated heated.. Care Care was was taken not to apply solder directly onto the top of the iron. - Enough Enough solder solder was was applied applied to form form a tin, smooth smooth coating coating in all all metal metal part part in the connection. - The heat was allowed on the connection for an INSTANT after application of the solder has been stopped. This is to aid the flow of solder and insure against ‘Poor’ or ‘cooled’ solder connections. - Care was taken not tot move the soldered soldered connection connection until until the the solder solder has cooled (solidified), thus reducing the possibilities of improper soldering. - Ex Exce cess ss lea lead len length gth were ere cut as clos lose as poss possib ible le to the sold soldeering ring connections. 4.2 4.2
ENCLO NCLOS SURE URE CONST ONSTR RUCTI UCTIO ON
The enclosure enclosure was practic practically ally made made from a sheet of thin thin metal. metal. Using a meter rule and pencil, the require shape and size for the enclosure was marked. marked. The parts were were then joined joined together together with special special plastic glue glue to form the shape shown below.
Paste picture here…………
Fig. 4.2 Enclosure Using a hand drill with tiny drilling bit, screw holes and other relevant ventilation holes were performed. Factors that were considered before choosing a specific shape and size incl includ ude, e, a larg largee enou enough gh spac spacee insi inside de the the encl enclos osur uree to prev preven entt over over compression of the circuit board. 4.3
ASSEMBLING
Havng constructed the circuit board and the enclosure and being satisfied with the functionality of the constructed circuit, the project was assembled. Assembling was simply fixing the circuit board firmly in the enclosure and screwing that there was no conducting object like lead ball, nail etc inside the enclosure and also that enclosure was not to small for the circuit board since this might cause compression which might result to breakage or the Vero board track.
Prop Proper er conn connec ecti tion onss were were made made betw betwee eenn the the unit units. s. Th This is was was a beat beat complicated and demand great care and attention since the use of a lot of connecting wires were involved.
4.3 TESTING AND RESULT Testing of the project proved satisfactorily. The power cord was connected to the mains mains and the power power switch switch toggled toggled on. Using Using a multim multimete eter, r, the voltage levels at various points were taking to ensure that the correct amount of power was reaching all the unit. Expected voltages were, Vcc of all Ics…………………9V GND of all Ics………………..0V Ics………………..0V etc. The power supply output waveform observed with an oscilloscope is shown below.
µ§
Next, resistance test was carried out. This was to ensure the there was no open or close circuit within the board strips or the connecting wires. .>????????????????????????????????????????????? The test shows that the system functionality corresponds corresponds to design intention.
. 4.4.1 LIST OF TOOLS USED IN CONSTR CONSTRUCTIO UCTION N 1- Sold Solder erin ingg iro ironn 2- Pair Pair of plie pliers rs 3- Side Side cutt cutter er 4- Nails 5- Twee Tweeze zers rs
CHAPTER FIVE
5.0 5.0
CONC CONCLU LUSI SION ON AND AND RECO RECOMM MMEN ENDA DATI TION ON
This chapter consists of the conclusion and recommendation, and reference.
5.1
CONCLUSION
write this
5.2
RECOMMENDATION
write this References
1. µ^§ (2000) "µ "µPower Electronics: Energy Manager for Hybrid Electric Vehicles§". Vehicles§". Oak Ridge National Laboratory Review 33 (3). Retrieved on µ2006§2006§µ11-08§. 11-08§. 2. µ^§ Rodriguez, Jose; et al. (August 2002). "Multilevel Inverters: A Survey of Topologies, Controls, and Applications". IEEE Transactions on Industrial Electronics 49 (4): 724-738.
3. B.L Theraja and A.K Theraja (1995)
A TEXT BOOK OF
ELECTR ELE CTRICA ICAL L TCHNOL TCHNOLOG OGY Y publis publishh by public publicati ation on divisi division on of Nrja construction company CP/LTD pp 1457-1468 4. Alle Allell CL Atwo Atwood od K.W K.W (Joh (Johnn Auth Authur ur II) II) (197 (1973) 3) EL ELEC ECTR TRON ONIC IC ENGINEERING third edition, John willy and sons INC. 5. JC Moris Moris (1989) (1989),, ELE ELECTR CTRON ONICS ICS;; PRACTI PRACTICA CAL L APPLI APPLICAT CATION ION AND DESIGN, pub. Edward Arnold, pp 130. 6. R.J Maddoc Maddockk and D.M Calcul Calcultt (1987), (1987), ELECTRO ELECTRONIC NIC;; A COURSE COURSE FOR ENGINEERING, pub. Longman group LTD, ELBS Edition, pp 601. www.wikip edia.com/machine machine§§ 7. µwww.wikipedia.com/ 8. µ400 Hz Electrica E lectricall Systems System s§. Aerospaceweb.org . Retrieved on µ2007§2007§-µ µ05-21§. 05-21§. 9. Allan, D.J. (1991), "Power transformers – the second century", Power Engineering 10.
Journal , IEE .
11. Dixon, Lloyd, µ"Eddy Current Losses in Transformer Windings and Circuit Wiring"§ Wiring" § 12. Flanagan, William (1993). Handbook of Transformer Design and Applications. McGrawHill. µISBN 0-0702-1291-0§. 0-0702-1291-0§. 13. Harlow, James (2004). Electric Power Transformer Engineering . CRC Press. µISBN 08493-1704-5§. 8493-1704-5§. 14. Hindmarsh, John (1977). Electrical Machines and their Applications, 4th edition . Exeter: Pergammon. µISBN 0-08-030573-3§. 0-08-030573-3§. Internat ional Electrotechnical Electrot echnical Commission Comm ission§. §. µOtto Blathy, Miksa Déri, Károly 15. µInternational Zipernowsky§. Zipernowsky§. IEC History . Retrieved on µ2007§2007§-µ µ05-17§. 05-17§. 16. Kubo, T.; H. Sachs & S. Nadel (2001), µOpportunities for new appliance and equipment efficiency standards § , American Council for an Energy-Efficient Economy, at p39 17. McLaren, Peter (1984). Elementary Electric Power and Machines. Ellis Horwood. µISBN 0-4702-0057-X§. 0-4702-0057-X§. 18. McLyman, Colonel William (2004). Transformer and Inductor Design Handbook . CRC. µISBN 0-8247-5393-3§. 0-8247-5393-3§.
Charging unit
Switching Circuit
Thermal Monitor And indicator
Dc-Ac Inverter
Driver
Step-up Transformer
Motor Logic gate
Pulse Generator
Counter
Decoder
7-segmant display
