PROJECT REPORT

ELECTRICAL MACHINES

SECTION: F

SIR SYED UNIVERSITY OF ENGINEERING AND TECHNOLOGY

DEPARTMENT OF ELECTRONICS ENGINEERING

DC MOTOR SPEED CONTROLLING

SUBJECT:

ELECTRICAL MACHINES

SECTION:F

GROUP MEMBERS:

MOHSIN MERAJ 2012-EE-313 SHAHERYAR FARRUKH 2012-EE-314 MOIN AMAN 2012-EE-336

SUBMITTED TO:

SIR MUBEEN BALOCH

ACKNOWLEDGEMENT

We would begin to thank with ALLAH S.W.T without whose help we would have been unable to prepare the project presented.

We take this opportunity to express our profound gratitude and deep regards to our guide Sir Mubeen Baloch for his exemplary guidance, monitoring and encouragement throughout the course of this project.

We also take this opportunity to express a deep sense of gratitude to our other lab teachers, for their cordial support, valuable information and guidance, which helped us in completing this task through various stages.

Finally we extend our gratefulness to one and all who are directly or indirectly involved in the successful completion of this project report.

Mohsin Meraj (2012-EE-313)

Shaheryar Farrukh (2012-EE-314)

Moin Aman (2012-EE-336)

ABSTRACT:

This simple circuit is designed to be able to control the speed of a dc motor to apply it in various devices from a fan to a line follower robot. The circuit has two transistors that form a darlington pair, a potentiometer is connected to the base of the first transistor to vary the base resistance. The dc motor is connected to the collector of the second transistor. The speed of the motor is controlled by varying the base resistance of the first transistor. By increasing the resistance of the potentiometer the speed of the motor is decreased and vice versa. A diode is also connected in parallel with the motor that acts a switch to stop the flow of reverse current in the motor.WORKING PRINCIPLE:

The working principle behind any DC motor is the attraction and repulsion of magnets. The simplest motors use electromagnets on a shaft, with permanent magnets in the case of the motor that attract and repel the electromagnets. The reason for using electromagnets is so that it is possible to flip their magnetic field (their north and south poles).So the electromagnet is attracted to one of the permanent magnets. As soon as it reaches the permanent magnet, its north and south poles flip so that it is repelled from that magnet and attracted to the other permanent magnet.COMPONENTS ANALYSIS:

Voltage Regulator IC (7805):

The voltage regulator IC is used to give a fixed output voltage of 5 volts. It takes a higher voltage as input and gives a fixed voltage of 5 volts at its output.Motors:

The toy motor used in this circuit can be applied in various other circuits such as line follower circuits. This whole project is an application of this motor.

Battery:

This circuit is powered by a 5 V battery.LED:

The glowing of the LED makes sure that the current is flowing in the circuit. If the LED does not glow, it is considered that there is some problem with the connection.CONCLUSION:

Applications of DC Motors:

The shunt motor has fairly constant speed as well as medium starting torque. It has the following applications: blowers and fans, lathe machines, centrifugal and reciprocating pumps, machine tools, milling machines and drilling machines.The series motor has variable speed and high starting torque. No-load speed is dangerous. It has the following applications:

cranes, trolleys, hoists and elevators, conveyers and electric locomotives.Cumulative compound motor has high starting torque, and no-load condition is allowed. It has the following applications:

punches, rolling mills, shears, elevators and heavy planers.The speed of differential motor increases with load and hence these motors are not suitable for practical applications.

PROBLEMS FACED: Circuit making while soldering. Equipments limitations caused many obstacles.

DATA SHEETS:

LM7805 IC:

2N3904: