MINI PROJECT FOR SEM-4 ,DEGREE ELECTRICAL

1. i
PROJECT PRESENTED BY:-
1. SHIVAM SINGH (EN NO.121110109045)
2. ASHAB ANSARI (EN NO.121110109025)
3. ALOK THAKUR (EN NO.121110109022)
4. RAVI NAYAK (EN NO.121110109041)
PROJECT GUIDED BY:-
SIR. ARVIND MISHAL

2. ii
I WOULD LIKE TO GIVE MY SPECIAL
THANKS TO SIR. MR ARVIND MISHAL, FOR HELPING AND
GUIDING US IN MAKING THIS MINI PROJECT.
THE TOPIC OF MINI PROJECT “SPEED
CONTROL OF D.C. MOTOR USING PWM METHOD” WAS
TAKEN BY OUR GROUP MEMBERS IN GUIDANCE OF SIR.
ARVIND MISHAL ,SO WE HAVE HEREBY COMPLETED
OUR MINI PROJECT SUCCESSFULLY AND HOPE OUR
PROJECT IS MADE AS REQUIRED BY THE ELECTRICAL
AND ELECTRONIC WORKSHOP SUBJET IN SEMESTER 4
OF DEGREE ELECTRICAL (GTU).
WE ALSO THANKS ALL OUR SUPPORTING
MEMBERS ,WHO EVER GET INDULGED IN MAKING OUT
NEW IDEAS AND TECHNIQUES RELATED TO THE
PROJECT. THUS HEREBY WE THANK ALMIGHTY IN
ORDER OF COMPLETING THIS MINI PROJECT AS
REQUIRED.

3. iii
ABSTRACT
The aim of development of this project is towards providing efficient and
simple method for control speed of DC motor using pulse width
modulation technique. The modulation of pulse width is obtained using
cd4010b Schmitt trigger and rectifier 1n4140.
There are several methods for controlling the speed of DC
motors. One simple method is to add series resistance using a rheostat.
As considerable power is consumed in the rheostat, this method is not
economical. Another method is to use a series switch that can be closed
or opened rapidly. This type of control is termed as chopper control. The
PWM based chopper circuit smoothly controls the speed of general
purpose DC motors.
To get desired modulation of pulse width as output, we
have used Schmitt trigger cd40106b and rectifier 1n4010b with regulator
as the source of varying output.

4. iv
TABLE OF CONTENTS
ACKNOWLEDGEMENT ......................................................Error! Bookmark not defined.
ABSTRACT ……………………………………………………………………………………………………………………………………………………iiii
TABLE OF CONTENTS.....................................................Error! Bookmark not defined.
GLOSSARY OF TERMS .............................................................................................. vv
1. INTRODUCTION TO PWM TECHNIQUE
1.1 GOAL.......................................................................................................7
1.2 PULSE WIDTH MODULATION (PWM) BASICS ......................................7
2. THEORY
2.1 COMPONENTS IN MINI PROJECT .......................................................10
2.2 GOAL(CD40106B)……………………………………………………………………………………………………………… 12
2.3 INTRODUCTION………………………………………………………………………………………………………….12
2.4 IFEATURES………………………………………………………………………………………………………………… 12
2.5 DIAGRAM……………………………………………………………………………………………………………… 13
2.6 REGULAR(CD40106B) ……………………………………………………………………………………… 14
2.7 APPLICATION…………………………………………………………………………………………………14
2.8 GOAL(1N4148)…………………………………………………………………………………….16
2.9 INTRODUCTION.................................................................16
2.10 FEATURES........................................................16
2.11 REGULAR(1N4148)...................................................17
2.12 APPLICATION......................................................................17
3. CIRCUIT DESIGN
3.1 CIRCUIT DESIGN OF MINI PROJECT ..........Error! Bookmark not defined.
4. CIRCUIT DESCRIPTION AND WORKING
4.1 EXPLANATION......................................................................................19
4.2 GOAL(PWM )…………………………………………………………………………………………….20
4.3 BLOCK DIAGRAM OF PWM……………………………………………………..20Error! Bookmark
not defined.
5. CONCLUTION
5.1 GOAL.....................................................................................................24
5.2 CONCLUSION .......................................................................................24
6. FUTURE MODIFICATIONS
6.1 GOAL.....................................................................................................26
6.2 POSSIBLE MODIFICATIONS ................................................................26

5. v
GLOSSARY OF TERMS
AC - Alternating Current
NPT - Non – Punch Through
CRO - Cathode Ray Oscilloscope
DC - Direct Current
IC - Integrated Circuit
PWM - Pulse Width Modulation
VR -Voltage Regulator

6. 6
1.
INTRODUCTION
TO PWM TECHNIQUE

7. 7
1.1 GOAL
“To explain PULSE WIDTH MODULATION technique in brief.”
1.2 Pulse Width Modulation (PWM) Basics
There are many forms of modulation used for communicating
information. When a high frequency signal has amplitude varied in response to a
lower frequency signal we have AM (amplitude modulation). When the signal
frequency is varied in response to the modulating signal we have FM (frequency
modulation. These signals are used for radio modulation because the high frequency
carrier signal is needs for efficient radiation of the signal. When communication by
pulses was introduced, the amplitude, frequency and pulse width become possible
modulation options. In many power electronic converters where the output voltage
can be one of two values the only option is modulation of average conduction time.
Fig. 1.1 Unmodulated, sine modulated pulses
1. Linear Modulation
The simplest modulation to interpret is where the average ON time of
the pulses varies proportionally with the modulating signal. The advantage of linear
processing for this application lies in the ease of de-modulation. The modulating
signal can be recovered from the PWM by low pass filtering. For a single low
frequency sine wave as modulating signal modulating the width of a fixed frequency
(fs) pulse train the spectra is as shown in Fig 1.2. Clearly a low pass filter can extract
the modulating component fm.

8. 8
Fig. 1.2 Spectra of PWM
2. Sawtooth PWM
The simplest analog form of generating fixed frequency PWM is by
comparison with a linear slope waveform such as a saw tooth. As seen in Fig 1.2 the
output signal goes high when the sine wave is higher than the saw tooth. This is
implemented using a comparitor whose output voltage goes to logic HIGH when ne
input is greater than the other. Other signals with straight edges can be used for
modulation a rising ramp carrier will generate PWM with Trailing Edge Modulation.
Fig. 1.3 Sine Sawtooth PWM
It is easier to have an integrator with a reset to generate the ramp in
Fig1.4 but the modulation is inferior to double edge modulation.

9. 9
Fig. 1.4 Trailing Edge Modulation
3. Regular Sampled PWM
The scheme illustrated above generates a switching edge at the instant
of crossing of the sine wave and the triangle. This is an easy scheme to implement
using analog electronics but suffers the imprecision and drift of all analog
computation as well as having difficulties of generating multiple edges when the
signal has even a small added noise. Many modulators are now implemented
digitally but there is difficulty is computing the precise intercept of the modulating
wave and the carrier. Regular sampled PWM makes the width of the pulse
proportional to the value of the modulating signal at the beginning of the carrier
period. In Fig 1.5 the intercept of the sample values with the triangle determine the
edges of the Pulses. For a saw tooth wave of frequency fs the samples are at 2fs.
Fig. 1.5 Regular Sampled PWM

10. 10
There are many ways to generate a Pulse Width Modulated signal
other than fixed frequency sine sawtooth. For three phase systems the modulation of
a Voltage Source Inverter can generate a PWM signal for each phase leg by
comparison of the desired output voltage waveform for each phase with the same
sawtooth. One alternative which is easier to implement in a computer and gives a
larger modulation depth is using space vector modulation.
4. Modulation Depth
Fig. 1.6 Saturated Pulse Width Modulation
For a single phase inverter modulated by a sine-sawtooth comparison,
if we compare a sine wave of magnitude from -2 to +2 with a triangle from -1 to +1
the linear relation between the input signal and the average output signal will be lost.
Once the sine wave reaches the peak of the transgle the pulses will be of maximum
width and the modulation will then saturate. The Modulation depth is the ratio of the
current signal to the case when saturation is just starting. Thus sine wave of peak
1.2 compared with a triangle with peak 2.0 will have a modulation depth of m=0.6.

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2.
THEORY

12. 12
2.1
COMPONENTS USED IN MINI PROJECT
“SPEED CONTROL OF D.C. MOTOR USING
PWM METHOD”
BATTERY
CAPACITOR
VARIABLE REGULATOR
HIGH SPEED DOIDE 1N4140
SCHMITT TRIGGER CD40106B
RESISTOR
MOTOR
AMPLIFIER TRANSISTOR

13. 13
INFORMATION
ON
Schmitt trigger CD40106B

14. 14
2.2 GOAL
“To study about Schmitt trigger CD40106B and its function in the
circuit.”
2.3 INTRODUCTION
CD40106B consists of six Schmitt trigger circuits.
Each circuit functions as an inverter with Schmitt trigger action on the input.
The trigger switches at different points for positive and negative-going signals.
The difference between the positive-going voltage (VP) and the negative-going
voltage(VN)is defined as hysteresis voltage(VH).
The CD40106B types are supplied in 14 lead hermetic dual-in-line ceramic
packages (D and F suffixes),14-lead dual-in-line plastic package(E suffix), and in
chip form (H suffix).
2.4 Features
 Schmitt-trigger action with no external components
 Hysteresis voltage(typ.) 0.9V at VDD=5V, 2.3V at VDD=10V, and 3.5V at
VDD=15V
 Noise immunity greater than 50%
 No limit on input rise and fall times
 Standardized, symmetrical output characteristics
 100% tested for quiescent current at 20V
 Maximum input current of 1mA at 18V over full package-temperature
range;100nA at 18V and25°C
 Low VDD to VSS current during slow input rampl 5V, 10V, and 15V
parametric ratings

15. 15
2.5 Functional diagram and logic diagram
of inverter CD40106B
Fig.Logic diagram (1 of 6 Schmitt triggers)

16. 16
2.6 REGULAR CD40106B
CD40106B SCHMITT TRIGGER
BY TEXAS INSTRUMENTS
2.7 Applications
Wave and pulse shapers
High-noise-environment systems
Monostable multivibrators
Astable multivibrators

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INTRODUCTION
ON
High speed diode
1N4148

18. 18
2.8 GOAL
“To study about high speed diode 1N4148”
2.9 INTRODUCTION
 The 1N4148 is a standard silicon switching diode.
 It is one of the most popular and long-lived switching diodes
because of its dependable specifications and low cost.
 Its name follows the JEDEC nomenclature.
 The 1N4148 is useful in switching applications up to about
100 MHz with a reverse-recovery time of no more than 4 ns.
 The 1N4148 comes in a DO-35 glass package for thru-
hole mounting.
 This is useful for breadboarding of circuits. A surface
mount device, 1N4148WS, is available in a plastic SOD package.
2.10 FEATURES
• Hermetically sealed leaded glass SOD27 (DO-35)
package
• High switching speed: max. 4 ns
• General application
• Continuous reverse voltage: max. 100 V
• Repetitive peak reverse voltage: max. 100 V
• Repetitive peak forward current: max. 450 mA.

19. 19
2.11 REGULAR 1N4148
2.12 APPLICATION
High-speed switching.

20. 20
3.
CIRCUIT DESIGN
3.1 “Circuit design of speed control of d.c. motor”

21. 21
4.
CIRCUIT DESCRIPTION
AND WORKING
4.1 EXPLANATION:
Here is a simple PWM motor speed controller circuit that
can be used for varying the speed of low power DC motors .
The variation in speed is achieved by varying the duty cycle
of the pulse supplied to drive the motor.
Of the two gates of IC CD40106B , N1 is wired as an
inverting Schmitt Trigger astable multi vibrator for producing
pulses and N2 as an inverting buffer to drive the transistor
during positive cycles at base.
The duty cycle is set from resistor R2.
R1 limits the base current of transistor SL 100. The circuit is
ideal for controlling toy motors,hand held mini fans , small
blowers etc.

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4.2 GOAL
“To explain working of the PWM circuit.”
4.3 BASIC BLOCK DIAGRAM
As shown in block diagram there are mainly three blocks: Astable
Multivibrator, Monostable Multivibrator and Driving Circuit.
Fig. 4.1 Block Diagram
The Basic Blocks are explained below:
 Astable Multivibrator: This block produce square pulses of same frequency
according to time constant RC. These pulses are fed to next block as triggering
pulses.
 Monostable Multivibrator: This block produces square pulses of variable
frequencies. The frequency of output pulse can be varied by changing the value of
resistor shown in figure. These pulses are fed to the driving circuit.
 Driving Circuit: This block provides power required to drive the motor. As the
frequency of output pulses of Monostable multivibrator changes, the average voltage
supplied to motor changes. Hence, the speed of motor changes.

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5.
CONCLUSION

24. 24
5.1 GOAL
“To conclude the work carried out.”
5.2 CONCLUSION
From the project work, following points can be concluded.
1.It fulfils all the requirements for its application.
2.The motor responds to the average value of the pulses and not to the individual
pulses as the chopper works at high frequency.
3.Changing the duty-cycle of the pulse by changing the speed of regulator changes
the average voltage level.
4.It is possible to improve overall performance of the motor speed.

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6.
FUTURE
MODIFICATIONS

26. 26
6.1 GOAL
“To highlight possible modifications that can be made in the project for
improving performance”.
6.2 POSSIBLE MODIFICATIONS
Following are the possible future modifications in our project work.
TABLE 10-1 FUTURE MODIFICATIONS
Sr.
No.
Modification Purpose
1 Use of micro-
controller/micro-processor
for closed loop operation
Constant speed variation
2 Use of MOSFET or IGBT Higher voltage and power requirement