This document discusses a project to control the speed of a DC motor using a microcontroller and pulse width modulation. Specifically, it aims to vary the speed-torque relationship of a DC motor electronically using a microcontroller to generate high and low pulses that control motor speed. Pulse width modulation is identified as a technique that can be used to simulate variable voltages through variations in pulse width to achieve variable analog speed control. The document outlines the components used, including an H-bridge circuit and microcontroller, and discusses some limitations such as susceptibility to electromagnetic interference.

1. Speed Control ofDC MotorUsingMicrocontroller
Oral Presentation
on
Prepared By-
1. Snehasis Bhar (25301613072)
2. Soumya De (25301613076)
3. Sudip Mondal (25301613087)
Sir J. C. Bose School of Engineering
(Supreme knowledge Foundation group of Institutions)
Mankundu ,Hooghly

2. INTRODUCTION
 The aim of developing this project is to control the speed of DC
motor.
 The main advantage in using a DC motor is that the Speed-
Torque relationship can be varied to almost any useful form.
 To achieve the speed control an electronic technique called Pulse
Width Modulation is used which generates High and Low pulses.
These pulses vary the speed in the motor.
 For the generation of these pulses a microcontroller (ATmega8) is
used to set the speed ranges as per the requirement.

4.  The electric and electromechanical methods are less
adaptive so electronic techniques are used for speed
control.
 One such technique is Pulse Width Modulation.
 We can easily apply this technique in Microcontroller
using Aurdino.
 It is easy to compile program with this language.

10. • H – Bridge Circuit Diagram
S1
__
S1
S2
__
S2
M
+
VCC Data S1 S2
00 OFF OFF
01 OFF ON
10 ON OFF
11 ON ON
-

11.  Pulse Width Modulation is a technique for getting analog
results with digital means.
 Digital control is used to create a square wave.
 This on-off pattern can simulate voltages in between full on
and off by changing the portion of the time the signal spends
on versus the time that the signal spends off.
 The duration of "on time" is called the pulse width. To get
varying analog values, you change that pulse width.
The green lines represent a regular time period. Arduino's PWM frequency
at about 500Hz, the green lines would measure 2 milliseconds each. A call to
analogWrite() is on a scale of 0 - 255, such that analogWrite(255) requests a
100% duty cycle (always on), and analogWrite(127) is a 50% duty cycle (on
half the time).

14.  Microcontroller needs software like compiler to
insert logics as inputs.
 It cannot interface high power devices directly.
 It is susceptible to EMI (Electromagnetic
Interference), sometimes even produces audible
noises.
 Speed control is little bit slow due to delay of clock
pulse.

15. We wish to express our sincere gratitude to Ms.
Srima Nandi, HOD of HU-Department for
giving us such opportunity to do a project. We
sincerely thank Mr. Vishwanath Gupta, Asst.
Prof. of EE-Department for guidance and
encouragement in carrying out this project
work.