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ACKNOWLEDGEMENT
Our Quest for practical knowledge led us in to the esteemed Organization
Automatic Electric Co. (Lonavla), which is a hall of fame. If words are considered as
symbols of approved and tokens of acknowledges, then let Words play the heralding role
of expressing our gratitude. We profusely thank our director Sri. Mr. Pramod Kale and
our university Coordinator Dr. D. Shaligram for their encouragement and support
through out the project.
We extend our heartiest thanks to our respected Project coordinator,
Mrs. Preeti Salunkhe, who is always a constant source of inspiration for us and for her
motivations in making this project completion.
We are very thankful to our beloved guide Ms. Jyutika Nalawade, for her
valuable and patient guidance throughout our endeavor. We remember With Regards and
respect the assistance and encouragement given by her. We are very much indebted to our
beloved parents who have given this opportunity to join in this course and are great
source of encouragement for us. Above all, the GRACE OF GOD of all creations led us
to complete our project successfully.
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EXECUTIVE SUMMERY
In our day to day life we use a lot many devices to satisfy our needs or to make
our life comfortable and luxurious. Every device needs a power supply, to work on. And
for the optimum functioning of the device it is necessary that the supply should be
reliable. That is, it should provide a constant voltage.
But this is not possible always. There are many reasons due to which there is a
fluctuation in the supply voltage. This change in the supply voltage may cause the
device to damage or make it work in an undesired way, which no one would desire.
Hence the best alternative is to regulate the supply voltage. This is what we have
tried to achieve here. Our project is supply voltage regulation, using controller and SCR.
In our project we provide the load with a constant voltage of 240 V ac., in spite of
any variation in the input voltage. The voltage regulation is achieved by controlling the
firing angle of the SCR so precisely that the load receives a constant supply. The
voltage across the load is stepped down and provided to ADC. ADC will produce a
digital signal corresponding to the input analog signal. This digital signal from ADC is
then processed by the controller and generates a firing pulse for SCR, hence controlling
the load current.
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INDEX
1. INTRODUCTION .………………………………………………. 4
2. AIM & OBJECTIVES ....………………………………………... 7
3. PROJECT PLANNING .…………………………………………. 9
4. BLOCK DIAGRAM ...………..………………………………… 12
5. BLOCK DIAGRAM DESCRIPTION .……….………………… 14
6. COMPONENT SEPECIFICATIONS .…………………………. 18
7. CIRCUIT DIAGRAM .…………………………………………. 47
8. FUNCTIONALITY .……………………………………………. 49
9. SOFTWARE FLOW CHART .…………………………………. 51
10. RESULTS & CONCLUSION .…………………………………. 58
11. BIBLIOGRAPHY .……………………………………………... 60
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CHAPTER 1
Introduction
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INTRODUCTION
In our day to day life we use a lot many devices to satisfy our needs or to make
our life comfortable and luxurious. Every device needs a power supply, to work on. And
for the optimum functioning of the device it is necessary that the supply should be
reliable. That is, it should provide a constant voltage.
But this is not possible always. There are many reasons due to which there is a
fluctuation in the supply voltage. This change in the supply voltage may cause the
device to damage or make it work in an undesired way, which no one will desire.
Hence the best alternative is to regulate the supply voltage. This is what we have
tried to achieve here. Our project is supply voltage regulation, using controller and SCR.
Silicon Controlled Rectifiers also called Thyristors controller, employing novel
technology, which is designed to provide a price effective solution for applications that
require power, current or voltage regulation with some power factor correction and a
smother process control. Traditional phase-angle control causes lots of harmonic
current distortion on the main power supply. This in turn creates voltage distortion which
affects power quality. There is no simple accessory available for reducing this problem.
However, when simple voltage or current regulation is required often phase-angle
control is the most cost effective solution.
Thyristors and triacs are switched on by using a gate. They automatically switch
off again when the conducted current reaches zero.
Therefore, these devices can be used in power regulators and by switching at a
predetermined position on the AC sine wave (the phase-angle) the effective voltage can
be reduced or increased. This can be used to regulate voltage or power to a load.
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In our project we provide the load with a constant voltage of 240 V ac., in spite of
any variation in the input voltage. The voltage regulation is achieved by controlling the
firing angle of the SCR so precisely that the load receives a constant supply. The
voltage across the load is stepped down and provided to ADC. ADC will produce a
digital signal corresponding to the input analog signal. This digital signal from ADC is
then processed by the controller and generates a firing pulse for SCR, hence controlling
the load current.
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CHAPTER 2
Aim & Objective
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AIM & OBJECTIVE
AIM:-
To develop a system for controlling fluctuation in the three phase Voltage supply
using SCR and Controller.
OBJECTIVE:-
To upgrade the existing three phase analog regulatory system, to a three phase,
microcontroller based SCR drive system. So that if any fluctuation comes in three phase
voltage supply, controller will Sense that fluctuation and accordingly give triggering
pulses to the SCR to get controlled regulated output at the load.
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CHAPTER 3
Project planning
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PROJECT PLANNING
Exactly what was planned in the project?
To design hardware for voltage regulation by using SCR bridge
To sense fluctuation in the single phase voltage supply.
To sense zero crossing of the input sine wave.
To get correct firing angle of SCR for getting correct control voltage.
To calculate the correct delay time for giving trigger pulse to SCR.
To trigger SCR depending upon calculated data and get the regulated
output.
To implement the same for three phase voltage supply.
What is achieved?
We designed hardware for voltage regulation by using SCR bridge
We sensed fluctuation in the single phase voltage supply.
We sensed zero crossing of the input sine wave.
We got correct firing angle of SCR for getting correct control voltage.
We calculated the correct delay time for giving trigger pulse to SCR.
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TIME SCHEDULING
S.NO SCHEDULE DAYS
1 Understanding project details 2
2 Finalizing project modules 3
3 Data collection 7
4 Selection of Microcontroller and its peripherals 4
5 Component search 11
6 Circuit Design 5
7 Hardware assembly 7
8 Hardware testing and debugging 7
9 Software coding (for calculating correct delay for different
angle)
2
10 Preparing look up table for different ADC values 1
11 Software coding(for voltage fluctuation) 3
12 Testing code on hardware 8
13 Project report & presentation 3
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CHAPTER 4
Block Diagram
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BLOCK DIAGRAM
POWER
SUPPLY
SCR
BRIDGE
CKT
230V AC
ADC
MICRO-
-CONTROLLER
O/P
ZERO
CROSSING
DETECTOR
CLOCK &
RESET
CKT
POTENTIAL
DIVIDER
24V AC
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CHAPTER 5
Block Diagram Description
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BLOCK DIAGRAM DESCRIPTION
POWER SUPPLY
This is the first block of our system. We have used a step-down centre tap
transformer, with the voltage rating of 240V ac as primary voltage and 24-0-24V ac as
the secondary voltage. The current rating of the transformer is 500mA.
The stepped-down ac signal is supplied to the rectifier & regulator. It consists of a
simple rectifier diode bridge network along with some filtering circuit, for smoothing out
the input signal. This filtered and rectified signal is then regulated using a positive
voltage regulator, to the desired value (say 5 V dc & 15 V dc) and also negative voltage
regulator to the desired value (say -15 V dc).For these purpose; we are using three
regulator chips.
LM7805 (+5V DC)
MC7815C (+15V DC)
L7915 (-15V DC)
The basic input requirement of the two regulators 7815 & 7915 is 23v dc. i.e. it
needs at lest this voltage to provide a constant +/-15V. This is why we have selected the
center-tap transformer of 24V dc. But the input voltage requirement of 7805 is just about
13v dc; hence we have reduced the voltage of the transformer to 13V through a resistor
in series.
The input of the regulator is provided with a filter capacitor of 10uF, 50v. and the
output with 0.01uf, forming a pie filter for better signal to noise ratio.
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ZERO CROSSING DETECTOR
This circuit is containing of OP-AMP UA 741.This is mainly used to detect the
zero crossing of the input sine wave so that we can get Synchronization.
The output of ZCD is given to the PORT pin 2.5 of the Microcontroller. Here ZCD
is used so that we can give trigger angle to the SCR at Correct time.
The op-amp in the ZCD is just a sine to square wave generator. It converts in the
input 24V ac signal to the square wave of 5 V and of the same frequency as that of the
sine wave. Op-amp UA 741 is provided with a dual supply, obtained from the positive
and negative regulators (+15V & -15V dc).
The output pin of the ZCD is provided with a rectifying diode which restricts the
negative signal from reaching the controller pin to avoid any damage to it.
SCR BRIDGE NETWORK
This block consists of a pair of SCR & diodes. Input to the SCR Bridge circuit is
fluctuated Single phase voltage supply, which is given to anode of both the SCRs and
cathode of both the diodes. Cathode of both the SCRs and Anode of both the diodes
are provided to the load. We have assumed a resistive load of 10K ohm. From this load
resistor one voltage signal will go to the Potential divider for feedback purpose. This will
act as the input signal to the ADC.
The gate of the SCR is connected to the PORT2.0 and PORT2.1. A specific
triggering pulse is provided to the gate of the SCR of sufficient time delay so as to keep
the load voltage constant.
POTENTIAL DIVIDER
To get controlled output we need to give feedback signal from the SCR bridge
circuit to ADC. But here feed back signal is nearer of 240V. So, we required to step it
down to the +5V.
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Because of this, here we have used potential divider network. From this potential
divider network we will get voltage signal around +5V. To obtain the voltage of 5V ac
from 240V ac we have used the network ratio of 59:1. The upper 59K resistor is fix while
the lower 1K is a pot of 10k. Then after this voltage signal is given to ADC0808.
ANALOG TO DIGITAL CONVERTER (ADC 0808)
Here we get input from potential divider network which is around +5V. Then this
analog value is converted to digital data and is given to Microcontroller. ADC 0808 has
four channels but we need only one, hence we have selected channel 0 for input. The 8
bit digital output of ADC is provided to the port 1 of controller.
MICROCONTROLLER 89C51RD2
This block is the only decision making block, which decides whether any
fluctuation in the supply line has occurred or not. It continuously compares the signal
with the reference described in the software. If there is no change then SCR will be fired
by it at phase angle 0 deg. But if it finds some fluctuation, then it will generate the pulse
at a measured time delay to provide the firing angle of the SCR (through gate) such that
the fluctuations will be nullified, and the supply to the load remains unaffected, in-spite
the fluctuations.
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CHAPTER 6
Components Specification
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COMPONENT SPECIFICATION
POWER SUPPLY
SPECIFICATION OF IC LM7805:-
_ 3-Terminal Regulators
_ Output Current up to 1.5 A
_ Internal Thermal-Overload Protection
_ High Power-Dissipation Capability
_ Internal Short-Circuit Current Limiting
_ Output Transistor Safe-Area Compensation
Description information
This series of fixed-voltage integrated-circuit voltage regulators is designed for a
wide range of applications. These applications include on-card regulation for elimination
of noise and distribution problems associated with single-point regulation. Each of these
regulators can deliver up to 1.5 A of output current. The internal current-limiting and
thermal-shutdown features of these regulators essentially make them immune to
overload. In addition to use as fixed-voltage regulators, these devices can be used with
external components to obtain adjustable output voltages and currents.
Absolute maximum ratings over virtual junction temperature range (unless
otherwise noted)
Input voltage, VI: A7824C 40 V)
All others 35 V
Operating virtual junction temperature, TJ 150C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds 260C
Storage temperature range, Tst -65C to 150C
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The LM7805 series of three terminal regulators are available with several fixed
output voltages. The voltages available allow regulators to be used in logic systems,
instrumentations, Hi-Fi and other solid state electronics equipment without any external
feedback components.
These ICs are designed as fixed voltage regulator and with adequate heat
sinking can deliver output currents in excess of 1A.The input capacitor Ci=0.33µF is
used, if regulator is located far from the power supply filter capacitor. It filters out the
effect of stray inductance of wire, ceramic or tantalum capacitor may be used. To
improve the transient response of regulator capacitor of 0.1µF is connected at output. It
utilizes common ground fir input and output and has dropout voltage (Vin – Vo) of 2 V.
Device type
with input
voltages
Output
voltage
(V)
Output
current
Quiescent
Current
(mA)
Line
regulation
(mV)
Load
regulation
(mV)
Ripple
rejection
(dB)
78XXC
(35)
5
12
15
1A 8 25
60
75
50
120
150
80
72
70
78LXXAC
(35)
5
12
15
100Ma 3 to 5
3 to5
3.1 to 5
10
20
25
5
10
12
62
54
51
78LXXC
(35)
5
12
15
100mA 3 to 6
3 to 6.5
3.1 to 6.5
10
20
25
5
10
12
60
52
49
78MXX
(35)
5
12
15
0.5A 4 to 10
4 to 10
4 to 10
50
120
150
100
240
300
78
71
69
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SPECIFICATION OF MC7815 (+15V REGULATOR)
These voltage regulators are monolithic integrated circuits designed as fixed–
voltage regulators for a wide variety of applications including local, on–card regulation.
These regulators employ internal current limiting, thermal shutdown, and safe–area
compensation. With adequate heat sinking they can deliver output currents in excess of
1.0 A. Although designed primarily as a fixed voltage regulator, these devices can be
used with external components to obtain adjustable voltages and currents.
• Output Current in Excess of 1.0 A
• No External Components Required
• Internal Thermal Overload Protection
• Internal Short Circuit Current Limiting
• Output Transistor Safe–Area Compensation
• Output Voltage Offered in 2% and 4% Tolerance
• Available in Surface Mount D2PAK and Standard 3–Lead Transistor Packages
• Previous Commercial Temperature Range has been extended to a Junction
Temperature Range of –40°C to +125°C.
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SPECIFICATION OF L7915 (-15V REGULATOR)
OUTPUT CURRENT UP TO 1.5A
OUTPUT VOLTAGES OF -5; -6; -8; -12; -15; -18; -20; -24V
THERMAL OVERLOAD PROTECTION
SHORT CIRCUIT PROTECTION
OUTPUT TRANSITION SOA PROTECTION
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The L7900 series of three-terminal negative regulators is available in TO-220,
TO-220FP, TO-3 and D2PAK packages and several fixed output voltages, making it
useful in a wide range of applications. These regulators can provide local on-card
regulation, eliminating the distribution problems associated with single point regulation;
furthermore, having the same voltage option as the L7800 positive standard series, they
are particularly suited for split power supplies. If adequate heat sinking is provided, they
can deliver over 1.5A output current. Although designed primarily as fixed voltage
regulators, these devices can be used with external components to obtain adjustable
voltages and currents.
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SPECIFICATION OF 1N4007 DIODE
• Low forward voltage drop.
• High surge current capability.
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ZERO CROSSING DETECTOR
SPECIFICATION OF UA741(OP-AMP)
LARGE INPUT VOLTAGE RANGE
NO LATCH-UP
HIGH GAIN
SHORT-CIRCUIT PROTECTION
NO FREQUENCY COMPENSATION
SAME PIN CONFIGURATION AS THE UA709
The UA741 is a high performance monolithic operational amplifier constructed on
a single silicon chip. It is intended for a wide range of analog applications.
-Summing amplifier
- Voltage follower
- Integrator
- Active filter
- Function generator
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The high gain and wide range of operating voltages provide superior
performances in integrator, summing amplifier and general feedback applications. The
internal compensation network (6dB/octave) insures stability in closed loop circuits.
PIN CONNECTIONS
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MICROCONTROLLER
SPECIFICATION OF MICROCONTROLLER 89C51RD2
The 89C51RB2/RC2/RD2 device contains a non-volatile 16kB/32kB/64kB Flash
Program memory that is both parallel programmable and serial In-System and In-
Application Programmable. In-System Programming (ISP) allows the user to
download new code while the microcontroller sits in the application. In-
Application Programming (IAP) means that the microcontroller fetches new
program code and reprograms itself while in the system. This allows for remote
programming over a modem link. A default serial loader (boot loader) program in
ROM allows serial In-System programming of the Flash memory via the UART
without the need for a loader in the Flash code. For In-Application Programming,
the user program erases and reprograms the Flash memory by use of standard
routines contained in ROM. This device executes one machine cycle in 6 clock
cycles, hence providing twice the speed of a conventional 80C51. An
OTPconfiguration bit lets the user select conventional 12 clock timing if desired.
This device is a Single-Chip 8-Bit Microcontroller manufactured in advanced
CMOS process and is a derivative of the 80C51 microcontroller family. The
instruction set is 100% compatible with the 80C51 instruction set. The device
also has four 8-bit I/O ports, three 16-bit timer/event counters, a multi-source,
four-priority-level, nested interrupt structure, an enhanced UART and on-chip
oscillator and timing circuits. The added features of the P89C51RB2/RC2/RD2
make it a powerful microcontroller for applications that require pulse width
modulation, high-speed I/O and up/down counting capabilities such as motor
control.
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FEATURES
80C51 Central Processing Unit.
On-chip Flash Program Memory with In-System Programming (ISP) and In-
Application Programming (IAP) capability.
Boot ROM contains low level Flash programming routines for downloading
via the UART.
Can be programmed by the end-user application (IAP)
6 clocks per machine cycle operation (standard)
12 clocks per machine cycle operation (optional)
Speed up to 20 MHz with 6 clock cycles per machine cycle(40 MHz equivalent
performance); up to 33 MHz with 12 clocks per machine cycle
Fully static operation
RAM expandable externally to 64 kB
4 level priority interrupt
8 interrupt sources
Four 8-bit I/O ports
Full-duplex enhanced UART
- Framing error detection
- Automatic address recognition
Power control modes
- Clock can be stopped and resumed
- Idle mode
- Power down mode
Programmable clock out
Second DPTR register
Asynchronous port reset
Low EMI (inhibit ALE)
Programmable Counter Array (PCA)
PWM
Capture/compare
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BLOCK DIAGRAM
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PIN DIAGRAM:-
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PIN DESCRIPTION
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OSCILLATOR CHARACTERISTICS
XTAL1 and XTAL2 are the input and output, respectively, of an inverting
amplifier. The pins can be configured for use as an on-chip oscillator. To drive the
device from an external clock source, XTAL1 should be driven while XTAL2 is left
unconnected. Minimum and maximum high and low times specified in the data sheet
must be observed.
This device is configured at the factory to operate using 6 clock periods per
machine cycle, referred to in this datasheet as “6 clock mode”. (This yields performance
equivalent to twice that of standard 80C51 family devices). It may be optionally
configured on commercially-available EPROM programming equipment to operate at 12
clocks per machine cycle, referred to in this datasheet as “12 clock mode”. Once 12
clock mode has been configured, it cannot be changed back to 6 clock mode.
RESET
A reset is accomplished by holding the RST pin high for at least two machine
cycles (12 oscillator periods in 6 clock mode, or 24 oscillator periods in 12 clock mode),
while the oscillator is running.
To ensure a good power-on reset, the RST pin must be high long enough to
allow the oscillator time to start up (normally a few milliseconds) plus two machine
cycles.
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At power-on, the voltage on VCC and RST must come up at the same time for a
proper start-up. Ports 1, 2, and 3 will asynchronously be driven to their reset condition
when a voltage above VIH1 (min.) is applied to RESET. The value on the EA pin is
latched when RST is reasserted and has a further effect.
LOW POWER MODES
Stop Clock Mode
The static design enables the clock speed to be reduced down to 0 MHz
(stopped). When the oscillator is stopped, the RAM and Special Function Registers
retain their values. This mode allows step-by-step utilization and permits reduced
system power consumption by lowering the clock frequency down to any value. For
lowest power consumption the Power Down mode is suggested.
Idle Mode
In the idle mode (see Table 2), the CPU puts itself to sleep while all of the on-
chip peripherals stay active. The instruction to invoke the idle mode is the last
instruction executed in the normal operating mode before the idle mode is activated.
The CPU contents, the on-chip RAM, and all of the special function registers remain
intact during this mode. The idle mode can be terminated either by any enabled interrupt
(at which time the process is picked up at the interrupt service routine and continued), or
by a hardware reset which starts the processor in the same manner as a power-on
reset.
Power-Down Mode
To save even more power, a Power Down mode (see Table 2) can be invoked by
software. In this mode, the oscillator is stopped and the instruction that invoked Power
Down is the last instruction executed. The on-chip RAM and Special Function Registers
retain their values down to 2.0 V and care must be taken to return VCC to the minimum
specified operating voltages before the Power down Mode is terminated.
Either a hardware reset or external interrupt can be used to exit from Power
Down. Reset redefines all the SFRs but does not change the on-chip RAM. An external
interrupt allows both the SFRs and the on-chip RAM to retain their values.
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To properly terminate Power Down, the reset or external interrupt should not be
executed before VCC is restored to its normal operating level and must be held active
long enough for the oscillator to restart and stabilize (normally less than 10 ms). With an
external interrupt, INT0 and INT1 must be enabled and configured as level-sensitive.
Holding the pin low restarts the oscillator but bringing the pin back high completes the
exit. Once the interrupt is serviced, the next instruction to be executed after RETI will be
the one following the instruction that put the device into Power Down.
SCR
SPECIFICATION OF MCR100
Introduction
PNPN devices designed for high volume, line-powered consumer applications such as
relay and lamp drivers, small motor controls, gate drivers for larger thyristors, and
sensing and detection circuits. Supplied in an inexpensive plastic TO-226AA package
which is readily adaptable for use in automatic insertion equipment.
Features
• Sensitive Gate Allows Triggering by Microcontrollers and Other Logic Circuits
• Blocking Voltage to 600 V
• ON State Current Rating of 0.8 Amperes RMS at 80°C
• High Surge Current Capability − 10 A
• Minimum and Maximum Values of IGT, VGT and IH Specified for Ease of
Design
• Immunity to dV/dt − 20 V/sec Minimum at 110°C
• Glass-Passivated Surface for Reliability and Uniformity
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SYMBOL
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Voltage Current Characteristic of SCR
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ANALOG TO DIGITAL CONVERTER
SPECIFICATION OF ADC 0808
General Description
The ADC0808 data acquisition component is a monolithic CMOS device with an 8-bit
analog-to-digital converter, 8-channel multiplexer and microprocessor compatible
control logic.
The 8-bit A/D converter uses successive approximation as the conversion technique.
The converter features a high impedance chopper stabilized comparator, a 256R
voltage divider with analog switch tree and a successive approximation register. The 8-
channel multiplexer can directly access any of 8-single-ended analog signals. The
device eliminates the need for external zero and full scale adjustments. Easy interfacing
to microprocessors is provided by the latched and decoded multiplexer address inputs
and latched TTL TRI-STATEÉ outputs. The design of the ADC0808 has been optimized
by incorporating the most desirable aspects of several A/D conversion techniques. The
ADC0808 offers high speed, high accuracy, minimal temperature dependence, excellent
long-term accuracy and repeatability, and consumes minimal power. These features
make this device ideally suited to applications from process and machine control to
consumer and automotive applications.
Features
Easy interface to all microprocessors
Operates ratio metrically or with 5 V dc or analog span adjusted voltage
reference.
No zero or full-scale adjust required
8-channel multiplexer with address logic
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0V to 5V input range with single 5V power supply
Outputs meet TTL voltage level specifications
Standard hermetic or molded 28-pin DIP package
28-pin molded chip carrier package
Key Specifications
Resolution 8 Bits
Total Unadjusted Error g(/2 LSB and g1 LSB
Single Supply 5 VDC
Low Power 15 mW
Conversion Time 100 ms.
Absolute Maximum Ratings (Notes 1 & 2)
If Military/Aerospace specified devices are required, please contact the National
Semiconductor Sales Office/Distributors for availability and specifications.
Supply Voltage (VCC) (Note 3) 6.5V
Voltage at Any Pin b0.3V to (VCC+0.3V) Except Control Inputs
Voltage at Control Inputs -0.3V to +15V
(START, OE, CLOCK, ALE, ADD A, ADD B, ADD C)
Storage Temperature Range -65C to +150C
Package Dissipation at TAe25C 875 mW
Lead Temp. (Soldering, 10 seconds)
Dual-In-Line Package (plastic) 260C
Dual-In-Line Package (ceramic) 300C
Molded Chip Carrier Package
Vapor Phase (60 seconds) 215C
Infrared (15 seconds) 220C
ESD Susceptibility (Note 8) 400V
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 43 of 61
BLOCK DIAGRAM
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 44 of 61
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 45 of 61
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 46 of 61
CONNETION DIAGRAM:-
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 47 of 61
CHAPTER 7
Circuit Diagram
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 48 of 61
CIRCIUT DIAGRAM
R7
1k
D8
DIO
DE
C2
10uf
T1
TR
AN
SF
OR
ME
R C
T
1 5
6
4 8
D7
DIO
DE
2
-
+U8
UA
74
1C
3
26
7 14 5
Q1SCR
U2 LM7805
1 3VIN VOUT
D1 DIODE
U9
AD
C0
80
8 7
10
11
1216
22
232425
262728
12345
96
171415818192021
EOC
CLK
VCC
+VREF-VREF
ALE
ADDCADDBADDA
IN0IN1IN2IN3IN4IN5IN6IN7
OESTART
DB0DB1DB2DB3DB4DB5DB6DB7
VCC
VCC
Y1
20
MH
Z
C3
0.1
uf
R21 k
1
D4 DIODE
+5V
R21 k
C710 uf
U6
MC7815C1 3
VIN VOUT
R6R3
10k
R18.2 k
VCC
R4
R4
+ R
5 +
R6
= 5
9K
+15v
R5
C6 30 pf
-15v
C530 pf
D6DIODE
24v DC
U7L 7915
2 3VIN VOUT
D2DIODE
D3DIODE C4
0.1
uf
240v ac
Q2SCR
P2.5C510uf
U3
89
C5
1
9
1819
2930
31
12345678
2122232425262728
1011121314151617
3938373635343332
RST
XTAL2XTAL1
PSENALE/PROG
EA/VPP
P1.0P1.1P1.2P1.3P1.4P1.5P1.6P1.7
P2.0/A8P2.1/A9
P2.2/A10P2.3/A11P2.4/A12P2.5/A13P2.6/A14P2.7/A15
P3.0/RXDP3.1/TXD
P3.2/INT0P3.3/INT1
P3.4/T0P3.5/T1
P3.6/WRP3.7/RD
P0.0/AD0P0.1/AD1P0.2/AD2P0.3/AD3P0.4/AD4P0.5/AD5P0.6/AD6P0.7/AD7
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 49 of 61
CHAPTER 8
Functionality
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 50 of 61
FUNCTIONALITY
Here, in our project we are controlling the single phase supply voltage 240V ac
by triggering the SCR from Microcontroller.
Main purpose of our project is to get constant 240 V dc at load. To fulfill this task
we have to control the firing angle of SCR trigger pulse. And for control purpose
we have used Philips 89C52RD2 Microcontroller.
Main parts of our circuits are SCR bridge circuit, Power supply, Zero crossing
detector, Potential divider.
The input to the SCR bridge circuit is 240V ac. From this circuit we get output
which will initially be fluctuating so for controlling purpose we will take a feedback
signal from output.
Now, we have to give this feedback signal to Analog to Digital converter but here
the feedback signal is of around 240V dc. When ADC 0808 can operates up to
+5 V dc. It will be damaged if we apply 240V dc to it. So for that we must have to
use some kind of step down circuitry. Here we have used Potential divider
circuitry. By the use of Potential divider we will step it down to around +5V dc
signal. Now it is safe to apply that signal to ADC 0808.
Here input to the ADC 0808 is analog signal which will be converting to the digital
signal. And that digital signal will be fed to the Microcontroller.
Microcontroller is the main decision making block of our project which is used to
control the firing angle of SCR. Digital signal which we get from the ADC 0808 is
then compared to the values which are stored in look table. And according to that
look table controller will take required value of firing angle. As per firing angle
controller will calculate the delay and according that delay Controller will give
triggering pulses to the gate of the SCR. So that we get controlled output.
But controller must have to give the triggering pulses at correct time means it
must have be synchronization with input signal. For that purpose we have used
zero crossing detector. So that when input analog signal will cross zero voltage
level, then only controller will give trigger pulse to the SCR.
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 51 of 61
CHAPTER 9
Software Flow-chart
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 52 of 61
Flow charts: Main Program:
START
Set port P1 as
input port
Read output of
ADC
Delay calc. for
firing pulse
Delay for
firing pulse
Set port pin
P2.0
Pulse width
delay
Reset port pin
P2.0
Is ZCD=1
A
R
No
Yes
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 53 of 61
A
Set port pin
P2.1
Delay for
firing pulse
Delay calc. for
firing pulse
Read output
from ADC
Is
ZCD=1
Reset port pin
P2.1
Pulse width
delay
R
Yes
No
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 54 of 61
Read output of ADC:
Start
Activate
SOC
Monitor
EOC
Activate output
enable
Activate
ALE
End
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 55 of 61
Pulse width Calculation:
Start
Reset timer
flag
Stop
timer
Start
timer
Load timer
register
Set timer in
mode zero
Is
TF=1
End
Yes
No
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 56 of 61
Delay calculation for firing pulse:
Start
Get value for
timer register
from look-up
table
End
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 57 of 61
Delay for firing:
Start
End
Set timer in
mode zero
Load timer
with ADC Val.
Start
timer
Stop
timer
Reset timer
flag
Is
TF=1
No
Yes
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 58 of 61
CHAPTER 10
Result & Discussion
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 59 of 61
RESULT AND DISCUSSION
Here by we have designed a device that is capable of detecting the fluctuations
in the input mains supply.
We designed hardware for voltage regulation by using SCR Bridge, which
senses fluctuations in the single phase voltage supply across the load and nullifies it.
Hence our device is capable of regulating the single phase mains supply to a
constant dc supply across the load, irrespective of any changes in the supply, hence
providing protection to the load device from getting damaged due to sudden variations
in the mains.
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 60 of 61
CHAPTER 11
Bibliography
A Project Report on Three Phase Voltage Regulation using SCR & Micro-Controller.
Techshristi.com ` Page 61 of 61
BIBLIOGRAPHY REFERENCE BOOKS:-
“The 8051 Microcontroller & Embedded System” by Mazidi.
8051 Micro controller by Kennith Ayala.
“Power Electronics” by Katre.
“Power Electronics” by Bhimra.
“OP-AMP &Integrated circuits” by Ramakant gayakwad.
WEB SITES:-
www.datasheets4u.com
www.datasheetcatalog.com
www.semiconductor.phillips.com
www.alldatasheet.com