8/10/2019 9-Intro to Electric Drives

1/3

30-10-20

E E 3 0 7

Prof. Paresh Kale

Dept. of Electrical Engineering,

NIT Rourkela.

SYLLABUS

30-10-2014 Electrical Drives by Dr. Paresh Kale 3

DC Motor

Transformer

Three Phase Alternator

Three Phase Synchronous Motor

Three Phase Induction motors

Single Phase Induction motor

Electric Drives

Special Electrical Machines

SYLLABUS

Introduction to electrical drive

Dynamics of electrical drives

Control of Electrical drives

Selection of motor power rating

Examples of various electrical drives

Energy conservation

Electrical drives systems and components

30-10-2014 Electrical Drives by Dr. Paresh Kale 4

TEXT BOOK FOR THIS CHAPTER

30-10-2014 Electrical Drives by Dr. Paresh Kale 5

30-10-2014 Electrical Drives by Dr. Paresh Kale 6

ELECTRICAL DRIVES :

AN INTRODUCTION

ELECTRICAL DRIVES

Motion control is required in large no. of industrial

applications

Transportation systems, rolling mills, paper machines,

textile mills, machine tools, fans, pumps, robots etc.

Drives control the motion: Use engines, turbines,

hydraulic motors

Electrical drives: Employ electric motors

30-10-2014 Electrical Drives by Dr. Paresh Kale 7

8/10/2019 9-Intro to Electric Drives

2/3

30-10-20

BLOCK DIAGRAM OF ELECTRICAL DRIVES

Load is machinery designed to accomplish a given task

Load requirements are specified in terms of speed and torque

30-10-2014 Electrical Drives by Dr. Paresh Kale 8

SourcePower

ModulatorMotor Load

Control Unit Sensing UnitInputcommand

FUNCTIONS OF POWER MODULATOR

Converter: Converts electrical energy from source to

suitable form

Modulates the power (Control of voltage)

Restricts source and motor currents within permissible

values during transient operations (e.g. Starting, braking,

speed reversal)

Selects the mode of operationof the motor i.e Motoring or

braking

30-10-2014 Electrical Drives by Dr. Paresh Kale 9

ADVANTAGES OF ELECTRICAL DRIVES

Flexible control characteristics Shaping of steady state and dynamic characteristics

Availability of microprocessors, power thyristors, modern electronics etc.

Available in wide range of torque, speed and power

Can operate in all four quadrants of N-T plane

Smooth operations

Energy conservations

Adaptable to all operating conditions

Electric motors have high efficiency

Low no load losses , overloading capability, compatibility with the load

No pollution

30-10-2014 Electrical Drives by Dr. Paresh Kale 10

PARTS OF ELECTRICAL DRIVES

Electrical motors DC / AC/ Synch / Special

Control Unit (Firing circuit)

Power Source 1 and 3sources (50 Hz)

Aircraft and space ( 400 Hz) (for high power to weight ratio) Traction ( 25 KV, 50 Hz or 1500V DC)

Battery ( fork lift trucks, solar powered drives)

Power modulators AC to DC converters ( Rectifiers) DC to DC Converters (Choppers)

AC voltage controllers or regulators (Transformers) Inverters (PWM)

Cycloconverter (Converts to variable voltage and variable frequency)

Variable impedances

Switching circuits (To change quadrant of motor operation, handle transient conditions,etc)

30-10-2014 Electrical Drives by Dr. Paresh Kale 11

SourcePower

ModulatorMotor Load

Control

UnitSensing UnitInput

command

AC DC CONVERTERS OR RECTIFIERS

30-10-2014 Electrical Drives by Dr. Paresh Kale 12

AC DC CONVERTERS OR RECTIFIERS

30-10-2014 Electrical Drives by Dr. Paresh Kale 13

8/10/2019 9-Intro to Electric Drives

3/3