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Design And Construction Of A Variable DC Motor Drive

The design and construction of a variable DC motor drive encompass a comprehensive process involving the integration of various electronic components and control techniques to regulate the speed and direction of a DC motor efficiently. It begins with selecting suitable components such as power transistors, diodes, capacitors, and resistors, considering parameters like voltage and current ratings, switching frequency, and heat dissipation capabilities to ensure optimal performance and reliability. Circuit design involves configuring power converters, such as buck or boost converters, to convert the input DC supply voltage into a controllable output voltage suitable for driving the motor. Control techniques like pulse-width modulation (PWM) are implemented to modulate the duty cycle of the switching signals, thereby regulating the motor’s speed. Additionally, feedback mechanisms such as closed-loop control systems utilizing sensors like encoders or Hall effect sensors provide accurate speed and position feedback for improved motor control. The construction phase involves assembling the designed circuit on a printed circuit board (PCB) or prototyping board, followed by thorough testing and debugging to ensure functionality and efficiency. Finally, the integration of protective features like overcurrent and overvoltage protection safeguards both the motor and the drive circuitry from potential damage, ensuring the longevity and reliability of the variable DC motor drive system.

ABSTRACT

DC motors are widely used in industries because of its versatile characteristics and because of power electronics devices its controlling is becoming sophisticated and precise, but on the other hand because of the power electronics devices power factor and total harmonics distortion problem is becoming more prominent. In this paper, DC motor control methodology was discussed.

TABLE OF CONTENTS

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

TABLE OF CONTENT

CHAPTER ONE

INTRODUCTION
AIM/OBJECTIVE OF THE PROJECT
SIGNIFICANCE OF THE PROJECT
SCOPE OF THE PROJECT
LIMITATION OF THE PROJECT
APPLICATION OF THE PROJECT
ADVANTAGES OF THE PROJECT
PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

2.0 LITERATURE REVIEW

2.1 OVERVIEW OF THE STUDY

2.2 REVIEW OF THE RELATED STUDY
2.10 REVIEW OF DC MOTOR

CHAPTER THREE

3.0 CONSTRUCTION METHODOLOGY

3.1 BLOCK DIAGRAM OF THE SYSTEM

3.2 CIRCUIT DIAGRAM

3.3 CIRCUIT DESCRIPTION

3.4 SYSTEM OPERATION

3.5 COMPONENTS LIST

3.6 DESCRIPTION OF MAJOR COMPONENTS USED

CHAPTER FOUR

4.0 RESULT ANALYSIS

4.1 CONSTRUCTION PROCEDURE AND TESTING

4.2 ASSEMBLING OF SECTIONS

4.3 CONSRUCTION OF THE CASING

4.4 ECONOMIC OF THE PROJECT

4.5 PROJECT VIABILITY

4.6 PROJECT RELIABILITY

4.7 PROJECT MAINTAINABILITY

4.8 PROJECT EVALUATION

4.9 TESTING, TROUBLESHOOTING AND REMEDY

CHAPTER FIVE

CONCLUSIONS
RECOMMENDATION

5.3 REFERENCES

CHAPTER ONE

1.0 INTRODUCTION

DC drives are DC motor speed control systems. Since the speed of a DC motor is directly proportional to armature voltage and inversely proportional to motor flux (which is a function of field current), either armature voltage or field current can be used to control speed

Because of low cost, less complex control structure and wide range of speed and torque, DC motor are popular in industry. Available methods of speed control of DC drives are field control, armature control and armature resistance control methods.

Speed of a DC motor can be controlled easily in both the ranges above and below the base speed. Most of the time, DC motors are customized at the time of installation as per the need which makes them irreplaceable. Armature voltage control method of speed control of DC drive is popularly used in which controlled rectifier or chopper are involved, though due to power electronics elements, an undesirable nonlinear torque speed characteristics are observed

The speed of dc motor is directly proportional to the supply voltage, if we reduce the supply voltage from 12V to 6V or the frequency

OBJECTIVE OF THE PROJECT

The objective of this work is to design a device that provides variable speed to a dc motor

SCOPE OF THE PROJECT

The only really satisfactory way of obtaining the variable-voltage d.c. supply needed for speed control of an industrial d.c. motor was to generate it with a d.c. generator. The generator was driven at fixed speed by an induction motor, and the field of the generator was varied in order to vary the generated voltage.

The motor/generator (MG) set could be sited remote from the d.c. motor, and multi-drive sites (e.g. steelworks) would have large rooms full of MG sets, one for each variable-speed motor on the plant.

For motors up to a few kilowatts the armature converter can be supplied from either single-phase or three-phase mains, but for larger motors three-phase is always used. Thyristor or diode rectifier can used to supply the field of the motor: the power is much less than the armature power, so the supply is often single-phase

It is accepted practice for motors supplied for use with thyristor drives to have laminated construction, but older motors often have solid poles and/or frames, and these will not always work satisfactorily with a rectifier supply. It is also the norm for drive motors to be supplied with an attached ‘blower’ motor as standard. This provides continuous through ventilation and allows the motor to operate continuously at full torque even down to the lowest speeds without overheating.

Low power control circuits are used to monitor the principal variables of interest (usually motor current and speed), and to generate appropriate firing pulses so that the motor maintains constant speed despite variations in the load.

1.3 PROBLEM OF THE PROJECT

Drawback of this method of dc motor speed control is that they are not able to control the motor speed smoothly at lower levels, and as the desired speed is decreased, the torque of the motor also decreases proportionately. Due to this, at any unpredictable point the motor may just halt very abruptly. Also, during power ON, the motor may just not start up at lower speed settings and may require an initial boost by increasing the setting. Such situations are pretty undesirable and do not constitute an ideal speed control.

1.4 APPLICATION OF THE PROJECT

This device is mostly use in controlling the movement and speed of other devices in industries such as in conveyors, Lathe Machines, Centrifugal Pumps, Fans, Blowers, Conveyors, Lifts, Weaving Machine, Spinning machines, etc.

1.5 PURPOSE OF THE PROJECT

The purpose of a motor speed control is to take a signal representing the demanded speed and drive the motor at a variable speed.

1.6 ADVANTAGES OF THE PROJECT

This work is a Simple control of motor speed, it has:

High reliability and
Low initial cost of production

1.7 PROJECT WORK ORGANIZATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this work is on the introduction to a variable dc motor drive. In this chapter, the background, significance, objective limitation and problem of a variable dc motor drive were discussed.

Chapter two is on literature review of a variable dc motor drive. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.