Design And Construction Of A DC Motor

ABSTRACT

A DC motor is any of a class of rotary electrical machines that converts direct current electrical energy into mechanical energy. The most common types rely on the forces produced by magnetic fields. Nearly all types of DC motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current flow in part of the motor.

In this paper the design of a 1KW dc motor with its all specific parts are done. What consists stator part like yoke, pole shoe, pole core, brushes, commutator, field winding etc. The design of rotating part like armature, armature winding, no of slots in armature windings are also explained in this paper for 1 KW dc motor. It also includes specific parameters used for designing 1KW dc motor like stator length, no of poles, no of turns in field winding. Copper Material with its mechanical strength is explained for making the field winding and armature winding. The cast iron is used as the protecting material for motor. Output questions like maximum speed of motor, torque generated for the motor are also calculated on the basis of these parameters.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

CHAPTER ONE

INTRODUCTION

1.1      BACKGROUND OF THE PROJECT

• AIM OF THE PROJECT
• OBJECTIVE OF THE PROJECT
• ADVANTAGES OF THE PROJECT
• DISADVANTAGES OF THE PROJECT
• APPLICATION OF THE PROJECT

CHAPTER TWO

LITERATURE REVIEW

• OVERVIEW OF THE STUDY
• REVIEW OF DIFFERENT TYPES OF DC MOTOR
• DC MOTOR CONNECTION
• HISTORICAL BACKGROUND OF THE STUDY

CHAPTER THREE

SYSTEM DESIGN METHODOLOGY

• COMPONENTS DC MOTOR
• PROPERTIES OF A DC MOTOR
• WORKING PRINCIPLE OF A DC MOTOR
• THEORY OF OPERATION
• DESIGN PROCEDURE
• EQUATIONS OF DC MOTOR

 CHAPTER FOUR

4.1 TESTING AND MAINTENANCE GUIDE

CHAPTER FIVE

• CONCLUSION
• REFERENCES

 CHAPTER ONE

1.0                                                        INTRODUCTION

A DC motor is a mechanically commuted electric motor powered from direct current (DC). The stator is stationary in space by definition and therefore the current in the rotor is switched by the commutator to also be stationary in space. This is how the relative angle between the stator and rotor magnetic flux is maintained near 90 degrees, which generates the maximum torque.

DC motors have a rotating armature winding (winding in which a voltage is induced) but non-rotating armature magnetic field and a static field winding (winding that produce the main magnetic flux) or permanent magnet. Different connections of the field and armature winding provide different inherent speed/torque regulation characteristics. The speed of a DC motor can be controlled by changing the voltage applied to the armature or by changing the field current. The introduction of variable resistance in the armature circuit or field circuit allowed speed control. Modern DC motors are often controlled by power electronics systems called DC drives.

DC motors are the most common type of motors used in robotics. DC motors appear in a large variety of shapes and sizes: permanent magnet iron core, permanent magnet ironless rotor, permanent magnet brushless, wound field series connected, wound field shunt connected, wound field compound connected, variable reluctance stepper, permanent magnet stepper, and hybrid stepper motors.

Another way of DC motor characterization is brush type and brushless DC motors. This characterization refers to the manner of commutation used in motor, which converts direct current from the batteries into the alternating current required to generate motor action. If this commutation is performed mechanically with brushes, the commutator segments at the ends of the rotating rotor col physically slide against the stationary brushes that are connected to the terminals of motor. These type of motors are brush type DC motors. For brushless motors, the DC is converted into AC in the rotor electronically with position sensors and a microprocessor controller, so no brushes are needed.

1.2                                                   AIM OF THE PROJECT

The aim of this work is to design a motor that is powered with direct current (dc) source.

1.3                                             OBJECTIVE OF THE PROJECT

After studying this chapter, you will be able to:

1. Construct a dc motor.
2. Explain the operation of electric motors in general and DC motors in particular
3. Explain the principles upon which DC motors operate Describe the construction of DC motors Discuss the different types of DC motors and their operating characteristics
4. Describe basic motor maintenance procedures
5. Basic Motor operation

1.4                                           ADVANTAGES OF DC MOTORS

1. Speed control over a wide range both above and below the rated speed: The attractive feature of the dc motor is that it offers the wide range of speed control both above and below the rated speeds. This can be achieved in dc shunt motors by methods such as armature control method and field control method. This is one of the main applications in which dc motors are widely used in fine speed applications such as in rolling mills and in paper mills.
2. High starting torque: dc series motors are termed as best suited drives for electrical traction applications used for driving heavy loads in starting conditions. DC series motors will have a staring torque as high as 500% compared to normal operating torque. Therefore dc series motors are used in the applications such as in electric trains and cranes.
3. Accurate steep less speed with constant torque: Constant torque drives is one such the drives will have motor shaft torque constant over a given speed range. In such drives shaft power varies with speed.
4. Quick starting, stopping, reversing and acceleration
5. Free from harmonics, reactive power consumption and many factors which makes dc motors more advantageous compared to ac induction motors.

1.5                                        DISADVANTAGES OF DC MOTORS

1. High initial cost
2. Increased operation and maintenance cost due to presence of commutator and brush gear
3. Cannot operate in explosive and hazard conditions due to sparking occur at brush ( risk in commutation failure)

1.6                                         APPLICATIONS OF A DC MOTOR

In depends on the type of DC motor, which applications are ideal. Generally speaking, the following applications are common.

• Cranes
• Conveyors
• Pumps
• Fans
• Machine tools
• Air compressors
• Toys
• Motor starters in cars
• robots