Study of DC drives

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Study of DC drives

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Abstract

In general practice in industrial applications machine tools make use of motors for their feed applications where in, speed of this motors are controlled in conventional methods i.e., Ward-Leonard system, multiple voltage control, rheostatic control method etc. However, these methods are obsolete now and offer a number of limitations like less reliability, less maintainability, poor system response etc. These limitations can be overcome by replacing the conventional methods with microprocessor controlled industrial drives.

Some of the advantages for using such drives for various purposes are. They can operate in all the four quadrants of sped-torque plane. Electric braking gives smooth deceleration and increases life of the equipment compared to other forms of braking. Considerable saving of energy is achieved. And some of the advantages for using such drives for various purposes are discussed at the end of the project.

Applications of dc motor in day-to-day life are vast. They're widely used in applications requesting adjustable speed, good speed regulation and frequent starting and braking and reversal. They can be found in application involving rolling mills, paper mills, hoists, machine tools, excavators, lifts, cranes, traction, printing press, textile mills etc. Through ac motors are used in pumps, fans, tractions, blowers, compressors, conveyers etc, ac drives become more costly than dc drives, and hence variable speed application are dominated by dc drives. Besides, the reliability and simple control of dc drives make them more popular.

Introduction to DC motors.
1. Introduction.
2. DC motor principle.
3. Types of motors.
4. Shunt motor and seperately excited motor.
5. Series motor.
6. Cumulative compound.
7. Starting of a DC motor.
8. Braking.
9. Regenerative braking.
10. Conclusion.
Speed controle.
1. Introduction.
2. Armature voltage control.
3. Field flux control.
4. Armature resistance control.
5. Conclusion.
Methods of armature voltage control.
1. Introduction.
2. Ward Leonard schemes.
3. Transformer and uncontrolled rectifier control.
4. Controled rectifier fed DC drives.
5. Chopper controled DC drive.
6. Conclusion.
Theory of electrical drives.
1. Introduction.
2. Block diagram of an electrical drive.
3. Parts of elecrical drives.
4. Choice of elecrtical drives.
5. Speed torque cinventions and multiquadrant operations.
6. Conclusion.
Control of drives.
1. Introduction.
2. Closed loop control of drives.
3. Digital control of DC drives.
4. Electrically controlled drive.
5. Block diagram of digital DC drives.
6. Conclusion.
The simoreg DC master controler.
1. Introduction: Description of simoreg DC master converter.
2. Design.
3. Mode of operation.
4. Nomenclature.
Interfacing.
1. Introduction.
2. Interfacing of DC motor to simoreg DC converter.
3. Relay.
4. Auxilary contact.
Commissioning.
1. Parameterization key.
2. Parameterization units.
3. Start up.
Advantages of DC drives.
Application of DC drives.
Case study.
Conclusion.
Bibliography.

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[...] The Torque developed by the motor Va = 2 Vm Cos ( = 2 Vm Cos 60o ( = 2 Vm x ( = Vm ( = ( 2 x 440 ( Va = 198.069 V Vf = 2Vm ( = 2 x 2 x 440) ( Vf = 396.139 V If = Vf Rf = If = 2.263 A Eg = Va Ia Ra = 198.069 45 x 0.25 Eg = 186.819 V Td = KV If Ia = 1.4 x 2.263 x 45 Td = 142.569 N-m Speed of the Motor: Eg = Kv If w 186.819 = 1.4 x 2.263 x w W = 58.966 rad/sec We know W = 2 ( N = 2 ( N 60 N = 60 x 58.966 N = 564 rpm OBSERVATIONS S.No Voltage Va (Volts) Vf (Volts) Td Speed (rpm) (volts) CASE STUDY CHOPPER-FED DC MOROR DRIVE USING MATLAB CIRCUIT DIAGRAM CIRCUIT DISCRIPTION The DC motor is fed by the DC source through a chopper which consists of GTO thyristor Th 1 and free-wheeling diode D1. [...]

[...] In the next chapter we are going to study about the SIMOREG DC MASTER CONTROLLER THE SIMOREG DC MASTER CONTROLLER 6.1 INTDROCUTION TO DESCRIPTION OF SIMOREG DC MASTER CONVERTER Series 6RA70 SIMOREG Dc master converters are fully digital, compact units for three phase supply which the armature and the field of variable speed DC drives with rated armature currents of between 15-2000 Amps. The compact converters can be connected parallel to supply currents of up to 40 Amps (current levels depend on the armature rated currents} DESIGN Series 6RA70 SIMOREG DC master converters are characterized by their compact, space saving construction. [...]

[...] In the next chapter we are going to study about the Methods of armature voltage control METHODS OF ARMATURE VOLTAGE CONTROL 3.1 INTRODUCTION Variable armature voltage for speed control, starting, braking and reversing of dc motors can be obtained by the following methods: When the supply is in ac Ward-Leonard schemes. Transformer with taps and uncontrolled rectifier bridge. Controlled rectifier When supply is dc Chopper control WARD-LEONARD SCHEMES WARD LEONARD DRIVES Known after the name of its inventor H.WardLeonard, it consists of a separately excited generator feeding the dc motor to be controlled. [...]

[...] In the next chapter we are going to study about the Control of Drives CONTROL OF DRIVES 5.1 INTRODUCTION Drives where the driving motor runs at nearly fixed speed are known as constant speed or single speed drives. Multi-speed drives are those, which operate at discrete speed settings. Drives needing change in speed and multi-speed drives are called variable speed drives. When a number of motors are fed from a common converter, or when a load is driven by more than one motor, the drive is termed as multi-motor drive. [...]

[...] And some of the advantages for using such drives for various purposes are discussed at the end of the project INTRODUCTION TO DC MOTORS 1.1 INTRODUCTION Applications of dc motor in day-to-day life are vast. They're widely used in applications requesting adjustable speed, good speed regulation and frequent starting and braking and reversal. They can be found in application involving rolling mills, paper mills, hoists, machine tools, excavators, lifts, cranes, traction, printing press, textile mills etc. Through ac motors are used in pumps, fans, tractions, blowers, compressors, conveyers etc, ac drives become more costly than dc drives, and hence variable speed application are dominated by dc drives. [...]

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