Contents

Preface xiii--xix

1 Industrialmotors 1

1 D.C. motors 1General 1Fundamental equations and performance 2

Wound-field motors 2Permanent-magnet motors 3

Operating principles 4Commutation 4Rotation 5Compensation 5D.C. PM commutation 6

Construction of the D.C. motor 6D.C. motor frame 6D.C. motor armature 6Brush gear 7Mountings 7D.C. PM design 7Rotor inertia 8Permanent-magnet materials 8

2 A.C. induction motors 8General 8Fundamental equations and performance 9

Electrical characteristics of induction motors 9Torque characteristics 10

Voltage-frequency relationship 11Increased voltage 12Reduced frequency 12

Slip-ring induction motor 13Speed-changing motors 13A.C. induction motor construction 14

3 A.C. synchronous motors 15General 15A.C. synchronous motor construction 17

4 Brushless servomotors 17General 17Principles of operation of brushless servomotors 18

Introduction 18Torque constant 18

Relationships between torque and back e.m.f.constant 19

Stationary torque characteristics 19Construction of brushless servomotors 20

Stator structure 20Rotor structure 20

5 Reluctance motors 216 A.C. commutator motors 227 Mechanical and environmental 22

Mounting of the motor 22General 22IEC 60034-7 standard enclosures 22NEMA standard enclosures 22

Degree of protection 24General 24IEC 60034-5 24US practice 25

Cooling 26General 26Air filters 27

Duty cycles 27Continuous duty -- S1 28Short-time duty -- S2 28Intermittent duty -- S3 28Intermittent duty with starting -- S4 29Intermittent duty with starting and electric

braking -- S5 29Continuous operation periodic duty -- S6 29Continuous operation periodic duty with

electric braking -- S7 29Continuous operation periodic duty with

related load speed changes -- S8 30Duty with nonperiodic load and speed

variations -- S9 30Duty with discrete constant loads -- S10 30

Terminal markings and direction of rotation 30General 30IEC 60034-8 30NEMA 32

Ambient conditions 33Introduction 33

W. Drury (Ed.)

The Control Techniques Drives and Controls Handbook

Temperature 33Altitude 34Power supply system 34

Noise and vibration 34General 34Vibration 34Noise 35

Motors for special applications 37Geared motors 37Brake motors 37Torque motors 37

Motors for hazardous locations 37General 37CENELEC 37North American standards 39Testing authorities 39

8 Effects of semiconductor power converters 40General 40Drive converter effects upon D.C. machines 40Drive converter effects upon A.C. machines 40

Introduction 40Machine rating -- thermal effects 40Machine insulation 40Bearing currents 46Overspeed 48

Motors for hazardous locations 48

2 Power electronics 51

1 Power semiconductor devices 51General 51Diode rectifier 51Thyristor 52

Thyristor gating requirements 54Power losses and current ratings 54Surge current ratings 55High-frequency current operation 56

Gate turn-off thyristor 56Switching characteristics and gate drive 57Snubber design 57Voltage and current ratings 57

Bipolar Transistor 57Voltage ratings 58Current ratings 58Switching characteristic and base drive 59Safe operating areas 60Short-circuit performance 61

MOSFET 61Voltage and current ratings 62Switching performance 62Safe operating area 62Parasitic diode 62

Insulated-gate bipolar transistor 63Operation 63Voltage and current ratings 63Switching behaviour and gate drive 63Safe operating area 64Short-circuit performance 64Series and parallel operation 64

Integrated-gate commutated thyristor 65Voltage and current ratings 65Switching behaviour and gate drive 65

Other power devices and materials 66

MOS-controlled thyristor 66MOS turn-off thyristor 66Silicon carbide 67

Power device packaging 67Pressure contact packages 67Large wire-bonded packages for power modules 67Small wire-bonded packages for discrete devices 69

Applications 702 Drive converter circuits 72

A.C. to D.C. power conversion 72General 72Converters for connection to a single-phase

supply 73Converters for connection to a three-phase

supply 74Voltage ripple characteristics 76Practical effects 76D.C. motor drive systems 76

D.C. to D.C. power conversion 79General 79Step-down D.C.-D.C. converters 79Step-up D.C.-D.C. converters 81

A.C. to A.C. power converters with intermediateD.C. link 81

General 81Voltage source inverters 81Current source inverters 83

Direct A.C. to A.C. power converters 85General 85Soft starter/voltage regulator 85Cycloconverter 86Static Scherbius drive 86Matrix converter 87

3 Speed and position feedback devices 89

1 D.C. tachometer generator 90General 90Output voltage ripple 90Temperature effects 91Linearity and load effects 91Stability of the output 91Maximum terminal voltage 91Maximum operating speed 91Mechanical construction 92

2 A.C. tachometer generator 923 Resolver 92

Design principles 93Synchros 93Torque synchros 93Control synchro 94Resolver 94

General 94Computing resolvers 94Phase shifting 95Brushless resolvers 95Multipole resolvers 95A.C. rotary pickoffs 95Resolver-to-digital conversion 96

4 Encoder 97Incremental encoder 97Absolute encoder 98Sin/cos encoder 99

vi Contentsvi

5 Selection of a feedback device for adrive system 99

6 Mechanical considerations 1007 Glossary of terms 101

4 Drive control 103

1 General 103The ideal control system 103Open-loop control 103Closed-loop control 104Criteria for assessing the performance of aclosed-loop control system 104

2 A.C. motor drive control 105General-purpose open-loop A.C. drive 106

Space-vector modulator and inverter 106Reference-frame translation 107Reference-frame generation 107Current limit 108Performance and applications 108

Permanent-magnet servodrive 109Reference-frame generation 109Current control 109Speed control 110Performance and applications 110

Closed-loop induction motor drive 110Flux calculator and reference-frame generation 111Flux control 111Performance and applications 111Operation without position feedback 111

Four-quadrant operation 112Reference-frame generation 112Performance and applications 112

Direct torque control 1133 D.C. motor drive control 114

Flux controller 114Torque controller 115Performance and applications 116

4 Analysis of and set up of a speed controller 116Ideal speed controller 116Calculating the required gains 117Nonideal effects in a real speed controller 119

5 Switched-reluctance and stepper-motordrives 121

1 General 1212 Switched-reluctance motors and controllers 122

Basic principle of the switched-reluctance motor 122Operation as a motor 123Operation as a brake or generator 123To summarise so far 123Relationship between torque polarity andmotoring/generating 124

Control of the machine in practice 124Low-speed operation 124What happens as speed is increased? 124Medium-speed operation 124How is performance maintained as speedincreases? 125

High-speed operation 125Summary of typical/practical control 126Control of speed and position 126

Polyphase switched-reluctance machines 127Losses in the switched-reluctance motor 127Excitation frequency 128Power electronics for the switched-

reluctance motor 128Power supply and front-end bridge 128Power switching stage 128Single-switch-per-phase circuits 128Multiple-phase operation 129Single-switch circuit using bifilar winding 129Two-switch asymmetrical bridge 130

Advantages of the switched-reluctance system 131Rotor construction 131Stator construction 131Electronics and system-level benefits 131

Disadvantages of the switched-reluctance system 132Torque ripple 133Acoustic noise 133

3 Stepper-motor drives 134Stepping-motor principles 134

The permanent-magnet motor 135The VR motor 135The hybrid motor 135

Stepping-motor drive circuits (logic modes) 136Unipolar switching 137Bipolar switching 137High-speed stepping -- L/R drives 139Chopper drives 139Bilevel drives 139Application notes 139

Effect of inertia 139Resonance 139

Special products 140Stepper/encoders 140Space-rated steppers 140Fuel-control actuators 140

6 Practical drives 141

1 General 141Digital input 143

Programmability 143Typical specification 143

Digital output 143Programmability 143Typical specification 143

Analogue input 143Programmability 143Typical specification 144

Analogue output 144Programmability 144Typical specification 144

2 D.C. drives 145The technology 145Drive selection 145Technical specifications and ratings 148Drive set up and commissioning 148

Autotune 148PC-based commissioning tools -- MentorSoft 148

Performance 148Speed and current-loop response 148

Typical applications 149Low-power analogue D.C. drives 149

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The 4Q2 D.C. drive 149Cheetah--Puma--Lynx 149

3 A.C. drives 151Features common to all A.C. drives 151

Power terminal layout 151Control terminal layout 151Wiring precautions to prevent electromagnetic

compatibility (EMC) issues 153Open-loop inverters 153

Specifications and ratings 153Features and options 153Methods of control 156Performance of the Commander SE open-loopdrive 156

Typical applications 157The universal A.C. drive 157

The concept of a universal drive 157Unidrive option modules 158Open-loop operation 159Closed-loop operation 159Servo operation 160Regeneration mode 162

High-performance servodrives 163Performance 166Summary of practical advantages of SLMtechnology 168

Applications 1694 Soft-start A.C. motor control 169

Conventional starting 169Direct-on-line starting (DOL) 169Star-delta starting 169Auto-transformer starting 170Disadvantages of conventional starting 170

Electronic soft start 171Typical applications 171

5 Application boards and software 172Applications module 172Software commissioning tools 173

Communications modes 173Drive set-up wizard 173Commissioning screen 174Monitoring screen 174Parameter list 174

7 Position and motion-control systems 175

1 General 1752 Basics of motion control 1773 Typical motion functions 180

Position lock -- electronic gearbox 180Direct positional lock 180Ramped nonrigid lock 180Ramped rigid lock 180

Simple single-axis positioning 182CAM functions 182Multiaxis positioning 183

4 Programmability 1875 Summary 188

8 Communications systems 189

1 Introduction 189Drive set up 190Drive control 191

Summary 1912 Network basics 191

Physical layer 192Network cables and connectors 192Interface circuits 192Data encoding 192Network topology 193

Data-link layer 194Framing 194Data model 194Media access control 194Error handling 195Conclusions 195

Application layer 195Device profile 195

3 Simple fieldbus systems 196Modbus 196Control Techniques' protocol 196

4 Fieldbus systems 197Requirements for drive applications 197

Physical layer 197Error detection 197Dynamic performance 197General message services 197Centralised versus distributed intelligence 197

Profibus DP 197Interbus-S 198CAN 198

DeviceNet 198CANopen 198

CTNet 198

9 Supply harmonics due to drives 199

1 Overview 1992 Regulations 200

Regulations for installations 200Regulations and standards for equipment 200

3 Harmonic generation within variable-speed drives 201A.C. drives 201D.C. drives 203

Effect of loading 2034 The effects of harmonics 2035 Calculation of harmonics 204

Individual drives -- D.C. 204Individual drives -- A.C. 205Systems 205Isolated generators 206

6 Remedial techniques 206Connect the equipment to a point with a highfault level (low impedance) 207

Use three-phase drives where possible 207Use additional inductance 207

Additional A.C. supply-line inductance 207Additional D.C. inductance 207

Use a higher pulse number (12 pulse or higher) 207Use a drive with an active input stage 211Use a harmonic filter 211

10 Electromagnetic compatibility (EMC) 213

1 Introduction 213General 213Principles of EMC 214

viii Contentsviii

EMC regulations 2142 Regulations and standards 214

Regulations 214Standards 215

3 EMC behaviour of variable-speed drives 215Immunity 215Low-frequency emission 216High-frequency emission 216

4 Installation rules 217EMC risk assessment 217Basic rules 217

Segregation 217Control of return paths, minimising

loop areas 217Earthing 218

Simple precautions and fixes 219Full precautions 219

5 Theoretical background 220Emission modes 220Principles of input filters 221Screened motor cables 222Ferrite ring suppressors 222Filter earth leakage current 222Filter magnetic saturation 222

6 Additional guidance on cable screening forsensitive circuits 223

Cable screening action 223Cable screen connections 223Recommended cable arrangements 225

11 Systems design 227

1 General 2282 Design matrix 2283 Dynamic/resistive braking 228

General 228D.C. motor braking 228

Example calculation of a brake resistor of aD.C. motor 231

A.C. regeneration and braking 231Example calculation of a brake resistorof a PWM A.C. induction motor drive system 232

4 Fusing 233General 233Protection of mains-drive and drive-motor cabling 233Protection of drive components 233

5 Motor overtemperature protection 234General 234Overtemperature protection of a converter-fedmotor 235

What can be used 235What cannot be used 235

6 A.C. drive motor cabling 236General 236Closed loop -- induction motor 236

Cable resistance 236Cable-charging currents 236

Closed loop -- PM servomotor 237Cable resistance 237Cable-charging currents 237

Open-loop current control--induction motor 237Cable resistance 237Cable-charging currents 237

Limits to cable length 237Example 240

Output chokes for long motor cable applications 240General 240Principles 240Calculations 240Example 241Position of chokes in multiple motorconfigurations 241

Typical recommended cable size 2427 Power supply considerations 243

High or low line voltage 243Supply frequency variations 243Supply impedance/fault level 243

Low supply impedance 243High supply impedance 243Multiple drive installations 244

8 Thermal design of enclosures 244General 244Calculating the size of a sealed enclosure 244

Example 244Calculating the air flow in a ventilated enclosure 245

Example 2459 Installation and maintenance of standard motors

and electronic equipment 246Motors 246

General 246Storage 246Installation 246Maintenance guide 247Brush gear maintenance 247

Electronic equipment 248General 248Siting of equipment 248Ventilator systems and filters 249Condensation and humidity 249Fuses 249

10 Common D.C. bus configuration of A.C. drives 250General 250A simple bulk uncontrolled rectifier 250Using the mains supply converter in one drive to

supply all drives from its D.C. link 252Effectively hard paralleling of all drive input

rectifiers 252A bulk four-quadrant controlled rectifier feedingthe D.C. bus 252

A bulk four-quadrant PWM converter feedingthe D.C. bus 253

Note on EMC filters for common D.C.bus systems 254

11 Mechanical vibration, critical speed andtorsional dynamics 255

General 255Example 255

Causes of shaft vibrations independent ofvariable-speed drives 255

Subsynchronous vibrations 256Synchronous vibrations 256Super-synchronous vibrations 256Critical speeds 256

Applications where torque ripple excites aresonance in the mechanical system 256

High-performance closed-loop applications 257

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Limits to dynamic performance 257System control-loop instability 257

Measures for reducing vibration 257

12 Applications 259

1 Typical load characteristics and ratings 259Metals industries 260Plastics 260Rubber 260Chemical 261Materials handling 261Lift, hoist and crane 261Concrete pipe manufacture 261Fans and blowers 262Pumps 262Paper and tissue 262Printing 262Packaging 263Engineering industries 263Wire and cable 263Hydraulics 263Electric motors and alternators 264Textiles 264Foods, biscuit and confection 264

2 Techniques common to many applications 264Special D.C. loads 264

Traction motor field control 264Battery charging 265Electrolytic processes 265Electric heating and temperature control 265

Digital slaving 266General 266Drive slaving techniques 266Principle of digital speed/position following 266The digital speed/position controller 267

Load sharing 268General 268D.C. thyristor converter-fed system 269A.C. inverter-fed systems 271

High-frequency inverters 272General 272Frequency control of A.C. induction motors 272High-frequency purpose-designed motors 273High-frequency inverters 274High-frequency applications 274

Centre winders 275General 275Speed or torque control 276Taper tension 276Constant torque and field weakening 276Power requirements for centre-driven winders 277

Inertia compensation 277Loss compensation 278Flux compensation 278Drive selection--limiting parameters 278

Sectional drive systems 278General 278Theory of operation 281Using an IEC61131-3 programming tool to

configure a sectional drive line 284Energy saving 284

General 284Centrifugal pumps 285Centrifugal fans and compressors 288

3 Application principles/examples 288Cranes and hoists 289

General 289Planning an installation 289Slewing control 289Crane refurbishment for a Norwegian steel wirerope maker 290

Elevators and lifts 291Lift system description 291Speed profile generation 292Load weighing devices 292

Metals and metal forming 292Winding, crimping and precise cutting 292Roll feed line 295

Wire and cable manufacture 296Four-quadrant D.C. drives for a bar mill 296Wire-drawing machine 296

Paper manufacturing 297General 297Sectional drives 297Loads and load sharing 298Control and instrumentation 299Winder drives 300Brake generator power and energy 301Unwind brake generator control 302Coating machines 302Paper-slitting machine 303Paper board machine 303

Building materials 304Brick-handling line 304Roofing-tile manufacturing plant 305

Textiles 307Fabric-dyeing machine 307Quilting machine 308

Plastics extrusion 308General 308Basic extruder components 310Overall extruder performance 310Energy considerations 310Motors and controls 311

Food 312Control of hammermills in animal feedproduction 312

HVAC 313Air conditioning for driver and vehiclelicensing agency 313

Air-handling units at Oxford BrookesUniversity students' union 313

Steel 314Main mill drives 314Auxiliary drives 314

Chemical 315Enamel painting of fluorescent tubes 315

Marine applications 316Cable laying 316Pipe laying 318Control of lock gates and sluices 319

Printing 320Real-time registration and shaftless webtensioning control 320

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Offset printing presses 321Stage scenery -- film and theatre 322

James Bond film stunts 322Controlling acoustics 323Exhibition focal point -- the Control

Techniques' orchestra 323Rock concert 325Millennium Dome aerial ballet 326

Appendix A Standards for drives 329

A1 IEC (international) standards 330Planned future IEC61800 standards 332

A2 CENELEC (EC) standards 332A3 British standards 334A4 IEEE (USA) standards 335A5 UL (Underwriters' Laboratories, USA) standards 335A6 Other standards 335

Electricity Association, UK 335EIA/TIA (previously RS) 335ANSI 335

Appendix B Symbols and formulae 336

B1 SI units and symbols 336SI base units 337Decimal multiples and submultiples 337Derived units 337

Geometrical units 337Time-related units 337Mechanical units 337

B2 Electrical formulae 338Electrical quantities 338A.C. three-phase (assuming balanced

symmetrical waveform) 338A.C. single phase 338Three-phase induction motors 338Loads (phase values) 338Impedance 338A.C. vector and impedance diagrams 338E.m.f., energy transfer 339Mean and r.m.s. values, waveform 340

Principles 340Mean D.C. value 340R.m.s. value 341Other waveforms 341Form factor 341

B3 Mechanical formulae 342Laws of motion 342

Linear motion 342Rotational or angular motion 343Relationship between linear andangular motion 343

The effect of gearing 344Friction and losses 344Fluid flow 345

B4 Worked examples of typical mechanical loads 346Conveyor 346

Data 346

Method 346Calculate speeds and gearing ratio 346Load, force and torque 346Power ratings for the motor and drive 347

Inclined conveyor 348Hoist 348

Data 348Velocity ratio (VR) 348Speed and acceleration of the hook 348Lifting force and torque to accelerate fromrest to full speed 348

Lifting force and torque to maintain full speed 349Required motor power rating 349Drive module power rating 349

Screw-feed loads 349

Appendix C Tables 351

C1 Mechanical conversion tables 351Length 351Area 352Volume 352Mass 353Energy 353Inertia 353Torque 354Force 354Power 354

C2 General conversion tables 354Length 354Area 354Volume 355Mass 355Force and weight 355Pressure and stress 355Velocity (linear) 355Velocity (angular) 355Torque 355Energy 355Power 355Moment of inertia 356Temperature 356Flow 356Torque 356Force 356Moment of inertia 356Linear acceleration 356

C3 Power/torque/speed nomogram 357

Appendix D World industrial electricitysupplies (< 1 kV) 358

Appendix E Bibliography and furtherreading 363

Index 365

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