ELECTRIC DRIVES N.K. DE P.K. SEN

Size: px

Start display at page:

Download "ELECTRIC DRIVES N.K. DE P.K. SEN"

Justina Potter
6 years ago
Views:

1 ELECTRIC DRIVES N.K. DE P.K. SEN

2 Electric Drives NISIT K. DE Associate Professor Department of Electrical Engineering Indian Institute of Technology Kharagpur and PRASANTA K. SEN Assistant Professor Department of Electrical Engineering Regional Engineering College Durgapur Delhi

3 ELECTRIC DRIVES by Nisit K. De and Prasanta K. Sen 1999 by PHI Learning Private Limited, New Delhi. All rights reserved. No part of this book may be reproduced in any form, by mimeograph or any other means, without permission in writing from the publisher. ISBN The export rights of this book are vested solely with the publisher. Sixteenth Printing January, 2014 Published by Asoke K. Ghosh, PHI Learning Private Limited, Rimjhim House, 111, Patparganj Industrial Estate, Delhi and Printed by Meenakshi Printers, Delhi

4 CONTENTS Preface ix 1. INTRODUCTION Concept of Electric Drives Classification of Electric Drives Group Electric Drive Individual Electric Drive Multi-motor Electric Drive Classification of Control Schemes Manual Control Semiautomatic Control Automatic Control Classification of Methods of Speed Control The First Group The Second Group The Third Group The Fourth Group The Fifth Group Components of Electric Drives Motors Power Electronic Controllers 6 2. SPEED-TORQUE CHARACTERISTICS OF MOTORS Basic Parameters Types of Loads Quadrantal Diagram Speed-Torque Characteristics of DC Shunt Motors Construction of Speed-Torque Characteristics Types of Braking Dynamic or Rheostatic Braking Counter Current Braking (Plugging) Regenerative Braking Determination of Starting, Dynamic Braking and Plugging Resistance for DC Shunt Motors Speed-Torque Characteristics of DC Series Motors Construction of Speed-Torque Characteristics Determination of Starting Resistance for DC Series Motors Types of Braking (Applications in DC Cranes) 32 iii

5 iv Contents 2.6 Speed-Torque Characteristics of DC Compound Motors Cumulative Compound Motor Types of Braking Differential Compound Motor Torque-Speed Characteristics of Induction Motors Torque Equation, Typical Starting Performance Starters for Slip-ring Induction Motors Types of Braking Synchronous Motor Excitation Control Braking of Synchronous Motors 56 Problems SPEED CONTROL OF DC MOTORS Basic Parameters Speed Control of DC Shunt Motors Ward-Leonard Method Buck-boost Control Speed Control of DC Series Motors Series-Parallel Control Speed Control (during Lowering) of a DC Series Motor in a Crane using Dynamic Braking Solid State DC Drives Thyristor Bridge Rectifier Circuits Chopper Circuits Bridge Rectifier-fed Drive DC Motor Controllers Controllers for DC Shunt Motors Microprocessor-based Controller for DC Motor Drives State Feedback Controller for DC Motor Drives Combined Observation and Control Feedforward Control Software for the Controller DC Motor Speed Control System Stepper Motors VR Stepper Motor Permanent Magnet (PM) Stepper Motor Hybrid Stepper Motor Stepper Motor Control 114 Problems SPEED CONTROL OF AC MOTORS Introduction Speed Control of Induction Motors Pole Changing Induction Motor Stator Frequency Variation 123

6 Contents v 4.3 Speed Control of Slip-Ring Induction Motors Stator Voltage Variation Rotor Resistance Variation Slip Power Recovery Basic Inverter Circuits Variable Voltage Variable Frequency (VVVF) Control Current Source Inverter AC Regulator Cycloconverter Speed Control of Synchronous Motors Input Frequency Variation Self-controlled Synchronous Motor Drive using Load Commutated Thyristor Inverter 147 Problems HEATING AND POWER RATING OF DRIVE MOTORS Load Diagram, Overload Capacity Insulating Materials Heating and Cooling of Motors Service Conditions of Electric Drives: Continuous, Intermittent and Short Time Selection of Motor Power Capacity Continuous Duty Constant Load Motor Applications Continuous Duty Variable Load Motor Applications Operation of Electric Drives Incorporating Flywheel under Shock Loading Conditions 193 Problems TRANSIENTS AND DYNAMICS Equation of Motion Equivalent System Referring Torque to a Single Axis (Motor Shaft) Referring Moment of Inertia to a Single Axis (Motor Shaft) Referring Forces and Masses having Translational Motion to Motor Shaft Moment of Inertia Determination of Moment of Inertia Optimal Gear Ratio Referring Torques and Masses having Translational Motion at Variable Speeds Transients in DC Motors Transients in DC Motors with Armature Inductance Dynamic Braking of DC Shunt Motors Time of Braking Current during Dynamic Braking Counter Current Braking and Speed Reversal of DC Shunt Motors 223

7 vi Contents 6.13 Energy Associated with Transient Process of DC Shunt Motors Energy Loss during Starting Energy Loss during Dynamic Braking Energy Loss during Speed Reversal Dynamic (Transient) Response of Induction Motors Starting an Induction Motor with Pure Inertia Load Induction Motor Started on Load Counter Current Braking of Induction Motors Rotor Heating Dynamic Braking of Induction Motors Reduction of Energy Losses during Starting 242 Problems MOTOR STARTERS AND CONTROLLERS DC Motor Starters Starters Using Voltage Sensing Relays Starters Using Current Sensing Relays Starters Using Time Delay Relays Wound Rotor Induction Motor Starters by Variation of Rotor Resistance (Mine Hoist) Starters Using Time Delay Relays Starters Using Frequency Sensing Relays Induction Motor Starters DOL Starter with Provision for Speed Reversal Auto-transformer Starter Master Controller for Wound Rotor Induction Motors Starting Plugging and Speed Reversal Dynamic Braking Starters for Two-Speed Pole Changing Induction Motors Starter for Two-Winding Two-Speed Pole Changing Induction Motors with Provision for Reversal at Both Speeds Starter for Single-Winding Two-Speed Pole Changing Induction Motors with Provision for Speed Reversal (Constant Torque) Starter for Single-Winding Two-Speed Pole Changing Induction Motors with Provision for Speed Reversal (Constant Horsepower) Programmable Logic Controller (PLC) INDUSTRIAL APPLICATIONS Introduction Synchronous Motor Drives Induction Motor (Cage) Drives Induction Motor (Wound Rotor) Drives DC Motor Drives Control Systems 270

8 Contents vii 8.2 Rolling Mill Drives Reversing Mill Drives Screw-down Mechanism Continuous Mills Cold Rolling Mills and Automatic Gauge Control Cement Mill Weighfeeder Mill Drive Separator Blower Drive Cyclone Electric Traction Tractive Effort Requirements of Electric Traction Suitability of Series Motors Coefficient of Adhesion Supply Systems and Traction Motors Train Movement Layout of Electric Drives Speed Control Coal Mines Precautions Drum Winder Modern Winder Drives Shearer Conveyors in Long-wall Systems Auxiliary Motors Paper Mill Pulp Manufacture Paper Manufacture Paper Mill Drives and Control Machine Tool Drives Lathe Drilling Machine Milling Machine Shaping Machine Planer Grinding Machine Hydraulic Drives Textile Mill Spinning Mill Weaving Loom Motors 301 Bibliography 303 Answers to Problems Index

10 PREFACE The purpose of this book is to provide a thorough grounding in fundamental aspects of electric drives and is, therefore, suitable for use as a text by students pursuing undergraduate courses in electrical engineering and those preparing for AMIE examinations. The principal topics covered in sufficient depth are: motor characteristics, speed control of motors, selection of drive motors, transients in drive systems, motor starters and controllers, and application of drives in industries. The introductory discussion of Chapter 1 provides an idea of the coverage of the book and outlines important issues involved in design and application of electric drive systems. Chapter 2 discusses the speed-torque characteristics of both dc and ac motors and the methods of braking applied to electric drives. Chapters 3 and 4 deal with the speed control methods of dc and ac motors, respectively. Both the conventional and state-of-the-art methods of speed control, with an example of a microprocessor-based dc controller, are discussed in detail. Several forms of power electronic controllers are also described. Chapters 5 and 6 cover several other aspects of drive systems such as selection of drive motors for different duty cycles and transient behaviour and dynamics of drive systems during starting/braking, etc. Chapter 7 gives a description of various types of controller circuits used in starting/braking of motors. Lastly, Chapter 8 is devoted to a discussion of drive systems as used in different industries such as steel mills, cement mills, electric traction, coal mines, paper mills, machine tools, and textile mills. Each application is covered in depth and supported by appropriate illustrations. A large number of solved examples and unsolved problems are included in Chapters 2 to 6, necessary to enhance the understanding of the material presented. Answers to all the problems are provided at the end of the book. We wish to express our gratitude to our teachers who initiated us in this area, and several other colleagues in our respective institutes who helped us in improving the quality of the book. We are also grateful to all of those who assisted in preparing the manuscript. Finally, we want to express our love and appreciation to our families for their active support, patience and encouragement throughout the time we were writing this book. Nisit K. De Prasanta K. Sen ix

Electric Drives Publisher : PHI Learning ISBN : 9788120314 924 Author : Nisit K De

11 Electric Drives Publisher : PHI Learning ISBN : Author : Nisit K De And Prasanta K Sen Type the URL : Get this ebook

ELECTRICAL MACHINES. Theory and Practice. M.N. Bandyopadhyay

ELECTRICAL MACHINES. Theory and Practice. M.N. Bandyopadhyay ELECTRICAL MACHINES Theory and Practice M.N. Bandyopadhyay ELECTRICAL MACHINES Theory and Practice M.N. Bandyopadhyay Director National Institute of Technology Kurukshetra Delhi-110092 2014 ELECTRICAL