Abstract

WELL COME TO OUR PRESENTATION

Table of contentTITLE CHAPTER ONE………………………………………… INTRODUCTION…………………………………… PROBLEM STATEMENT …………………………… OBJECTIVES ………………………………………… SCOPE OF PROJECT…………………………………CHAPTER TWO…………………………………………… PULSWIDTH MODULATION…………………… ….SPEED CONTROLLER………………………………….DIRECTION CONTROL OF DC MOTOR………………CHAPTER THREE…………………………………………….IMPLMENTATION………………………………………CHAPTER FOUR ………………………………………… RESULT AND DESCRIPTION……………………………CONCLUSSION……………………………………………

1 INTRODUCTION

555 timer is widely used in various field, there are two main models in the data sheet Mono stable mode and a stable model, the main difference between them in our design is depend on if you want the initial setting to be high or low. It can also operate in high voltage (5-15v) range, it is high powered and at the same time able to be triggered by small current. In a modern industrial situation, DC motor is widely used which is due to the low initial cost, excellent drive performance, low maintenance and the noise limit.

Problem statement

In real world, motor applications not only use the maximum speed of motor. It maybe uses only

50% of its speed. So, the speed of the motor must be control. For some applications, motor is

using not only one direction but with alternate direction to control a machine. In industrial

field, some machine or cannot get in touch according to safety and the location of those things.

objectives

The purpose of develop 555 timer control is to set the position and timing of a flipper which is

attached to DC Motor.

The main objectives of this project

To control direction and vary the speed of DC motor by using timer

To develop a software using assembly language timer.

pecific objectives of project

Running the motor in forward direction for a specified time

Understand pulse width modulation (PWM) for speed control of dc motor

Understand about timer interrupts and PWM

Implement a simple finite-state machine using VHDL

Running the motor in forward and reverse direction for a specified time

Scope of project

Design a circuit for controlling speed and direction of DC motor.

CHAPTER TWO

Pulse width modulation Pulse an electromagnetic wave or modulation of brief duration Width Modulation - to adjust to or keep in proper measure or

proportion the width of the pulse with respect to the frequency of the wave

Advantages of pulse width modulation

The motor consumes less power Significantly less energy loss due to heat Allows finer motor control

Disadvantages of pulse width modulation

the life Shortens of the motor by putting more stress on the fan bearings and winding

The fan can ‘kick’ due to slow RPMs. Different types of waves: sine, square, saw tooth triangle PWM uses square waves Discrete on / off value.

SPEED CONTROL WITH PWM The important element of speed controller

A means of altering the voltage applied to the motor to control its speed A means of measuring the absolute speed of the motor shaft Some software running on a IC55 to keep the speed constant, despite a rapid

variation in caused by the clock gearing plus slow change in drag due to ambient temperature.

There are three ways to vary the speed of DC

1. With the use of mechanical gears to achieve the desired speed

2. Reduce the motor voltage with a series resistor. Higher the current, larger the

voltages drop across the series resistor and less voltage to the motor.

3. Apply full voltage supply to the motor in pulse and eliminate the series

dropping effect that called pulse width modulation (PWM). As the pulse

increase, the motor run faster.

CHAPTER THREE 

Implementation 

Software implementation

In this circuit, the DC motor is operated by a 555 integrated circuit. The IC 555 in this circuit is being operated in astable mode. In this mode, the circuit can be used as a pulse width modulator with a few small adjustments to the circuit. The frequency of operation of the circuit is provided by the passive parameters of resistances and capacitances attached to it. The duty cycle is governed by the resistor which is in between pin-6 and pin-7 of the IC 555 timer. So, by taking advantage of the circuits working, we can change the 555 a stable multivibrator into a pulse width modulator by using a variable resistor instead of a constant resistor in between pin-6 and pin-7. One of the best things about this circuit is that we can make it work as an a stable multivibrator with little hardware and by little cost which can save both the cost involved in making it as well as the space on the printed circuit board is saved.

Hardware Wiring Besides providing +12 VDC power directly to the PWM amplifier, all other connections are made with the breadboard that is wired to the amplifier. The blue connector plugged into the breadboard has 14 pins, numbered on the top. The table below gives the pin--out assignments of this connector. The hardware connections that you must make include power for the optical encoder, the PWM control signal and motor direction, and encoder

figure setup showing overall layout of all equipment used.

CHAPTER ROUR RESULT AND DESICUSSION The major reason for using pulse width modulation in DC motor control is to avoid the excessive heat dissipation in linear power amplifiers. The heat dissipation problem often results in large heat sinks and sometimes forced cooling. PWM amplifiers greatly reduce this problem because of their much higher power conversion efficiency. Moreover the input signal to the PWM driver may be directly derived from any digital system without the need for any D/A converters. The PWM power amplifier is not without disadvantages. The desired signal is not translated to a voltage amplitude but rather the time duration (or duty cycle) of a pulse. This is obviously not a linear operation. But with a few assumptions, which are usually Valid in motor control, the PWM may be approximated as being linear (i.e., a pure gain).

CONCLLUSSION

The proposed circuit acts as a simple, low-cost, light weight, efficient, and accurate design for PWM controlling the speed of a DC motor in forward direction, from fully off to fully on. Speed control of a DC motor via pulse width modulation of a fixed-voltage power supply is introduced. The PWM waveform is created using an operational amplifier (op-amp) circuit. The output transistor is either on or off, not partly on as with normal regulation, so less power is wasted as heat and smaller heat-sinks can be used. The proposed circuit is used for motor running at 12V or 9V and dawning up to about 5A. It runs in switch mode so it quite efficient. This simple circuit can run a DC motor in clockwise or anti-clockwise direction and stop it using a single potentiometer. The voltage on a DC motor can be suddenly reversed while it is spinning. This circuit overcomes both the big current surge that could burn out controller and big electrical and mechanical stresses on the motor.

THANKS TO ALL EGZAMINERS AND AUDIOUS !!!!!!! THE END!!!