The Control Techniques Drives and Controls Handbook

Contents Preface xiii--xix 1 Industrial motors 1 1 D.C. motors 1 General 1 Fundamental equations and performance 2 Wound-field motors 2 Permanent-magnet motors 3 Operating principles 4 Commutation 4 Rotation 5 Compensation 5 D.C. PM commutation 6 Construction of the D.C. motor 6 D.C. motor frame 6 D.C. motor armature 6 Brush gear 7 Mountings 7 D.C. PM design 7 Rotor inertia 8 Permanent-magnet materials 8 2 A.C. induction motors 8 General 8 Fundamental equations and performance 9 Electrical characteristics of induction motors 9 Torque characteristics 10 Voltage-frequency relationship 11 Increased voltage 12 Reduced frequency 12 Slip-ring induction motor 13 Speed-changing motors 13 A.C. induction motor construction 14 3 A.C. synchronous motors 15 General 15 A.C. synchronous motor construction 17 4 Brushless servomotors 17 General 17 Principles of operation of brushless servomotors 18 Introduction 18 Torque constant 18 Relationships between torque and back e.m.f. constant 19 Stationary torque characteristics 19 Construction of brushless servomotors 20 Stator structure 20 Rotor structure 20 5 Reluctance motors 21 6 A.C. commutator motors 22 7 Mechanical and environmental 22 Mounting of the motor 22 General 22 IEC 60034-7 standard enclosures 22 NEMA standard enclosures 22 Degree of protection 24 General 24 IEC 60034-5 24 US practice 25 Cooling 26 General 26 Air filters 27 Duty cycles 27 Continuous duty -- S1 28 Short-time duty -- S2 28 Intermittent duty -- S3 28 Intermittent duty with starting -- S4 29 Intermittent duty with starting and electric braking -- S5 29 Continuous operation periodic duty -- S6 29 Continuous operation periodic duty with electric braking -- S7 29 Continuous operation periodic duty with related load speed changes -- S8 30 Duty with nonperiodic load and speed variations -- S9 30 Duty with discrete constant loads -- S10 30 Terminal markings and direction of rotation 30 General 30 IEC 60034-8 30 NEMA 32 Ambient conditions 33 Introduction 33 W. Drury (Ed.) The Control Techniques Drives and Controls Handbook Temperature 33 Altitude 34 Power supply system 34 Noise and vibration 34 General 34 Vibration 34 Noise 35 Motors for special applications 37 Geared motors 37 Brake motors 37 Torque motors 37 Motors for hazardous locations 37 General 37 CENELEC 37 North American standards 39 Testing authorities 39 8 Effects of semiconductor power converters 40 General 40 Drive converter effects upon D.C. machines 40 Drive converter effects upon A.C. machines 40 Introduction 40 Machine rating -- thermal effects 40 Machine insulation 40 Bearing currents 46 Overspeed 48 Motors for hazardous locations 48 2 Power electronics 51 1 Power semiconductor devices 51 General 51 Diode rectifier 51 Thyristor 52 Thyristor gating requirements 54 Power losses and current ratings 54 Surge current ratings 55 High-frequency current operation 56 Gate turn-off thyristor 56 Switching characteristics and gate drive 57 Snubber design 57 Voltage and current ratings 57 Bipolar Transistor 57 Voltage ratings 58 Current ratings 58 Switching characteristic and base drive 59 Safe operating areas 60 Short-circuit performance 61 MOSFET 61 Voltage and current ratings 62 Switching performance 62 Safe operating area 62 Parasitic diode 62 Insulated-gate bipolar transistor 63 Operation 63 Voltage and current ratings 63 Switching behaviour and gate drive 63 Safe operating area 64 Short-circuit performance 64 Series and parallel operation 64 Integrated-gate commutated thyristor 65 Voltage and current ratings 65 Switching behaviour and gate drive 65 Other power devices and materials 66 MOS-controlled thyristor 66 MOS turn-off thyristor 66 Silicon carbide 67 Power device packaging 67 Pressure contact packages 67 Large wire-bonded packages for power modules 67 Small wire-bonded packages for discrete devices 69 Applications 70 2 Drive converter circuits 72 A.C. to D.C. power conversion 72 General 72 Converters for connection to a single-phase supply 73 Converters for connection to a three-phase supply 74 Voltage ripple characteristics 76 Practical effects 76 D.C. motor drive systems 76 D.C. to D.C. power conversion 79 General 79 Step-down D.C.-D.C. converters 79 Step-up D.C.-D.C. converters 81 A.C. to A.C. power converters with intermediate D.C. link 81 General 81 Voltage source inverters 81 Current source inverters 83 Direct A.C. to A.C. power converters 85 General 85 Soft starter/voltage regulator 85 Cycloconverter 86 Static Scherbius drive 86 Matrix converter 87 3 Speed and position feedback devices 89 1 D.C. tachometer generator 90 General 90 Output voltage ripple 90 Temperature effects 91 Linearity and load effects 91 Stability of the output 91 Maximum terminal voltage 91 Maximum operating speed 91 Mechanical construction 92 2 A.C. tachometer generator 92 3 Resolver 92 Design principles 93 Synchros 93 Torque synchros 93 Control synchro 94 Resolver 94 General 94 Computing resolvers 94 Phase shifting 95 Brushless resolvers 95 Multipole resolvers 95 A.C. rotary pickoffs 95 Resolver-to-digital conversion 96 4 Encoder 97 Incremental encoder 97 Absolute encoder 98 Sin/cos encoder 99 vi Contentsvi 5 Selection of a feedback device for a drive system 99 6 Mechanical considerations 100 7 Glossary of terms 101 4 Drive control 103 1 General 103 The ideal control system 103 Open-loop control 103 Closed-loop control 104 Criteria for assessing the performance of a closed-loop control system 104 2 A.C. motor drive control 105 General-purpose open-loop A.C. drive 106 Space-vector modulator and inverter 106 Reference-frame translation 107 Reference-frame generation 107 Current limit 108 Performance and applications 108 Permanent-magnet servodrive 109 Reference-frame generation 109 Current control 109 Speed control 110 Performance and applications 110 Closed-loop induction motor drive 110 Flux calculator and reference-frame generation 111 Flux control 111 Performance and applications 111 Operation without position feedback 111 Four-quadrant operation 112 Reference-frame generation 112 Performance and applications 112 Direct torque control 113 3 D.C. motor drive control 114 Flux controller 114 Torque controller 115 Performance and applications 116 4 Analysis of and set up of a speed controller 116 Ideal speed controller 116 Calculating the required gains 117 Nonideal effects in a real speed controller 119 5 Switched-reluctance and stepper-motor drives 121 1 General 121 2 Switched-reluctance motors and controllers 122 Basic principle of the switched-reluctance motor 122 Operation as a motor 123 Operation as a brake or generator 123 To summarise so far 123 Relationship between torque polarity and motoring/generating 124 Control of the machine in practice 124 Low-speed operation 124 What happens as speed is increased? 124 Medium-speed operation 124 How is performance maintained as speed increases? 125 High-speed operation 125 Summary of typical/practical control 126 Control of speed and position 126 Polyphase switched-reluctance machines 127 Losses in the switched-reluctance motor 127 Excitation frequency 128 Power electronics for the switched- reluctance motor 128 Power supply and front-end bridge 128 Power switching stage 128 Single-switch-per-phase circuits 128 Multiple-phase operation 129 Single-switch circuit using bifilar winding 129 Two-switch asymmetrical bridge 130 Advantages of the switched-reluctance system 131 Rotor construction 131 Stator construction 131 Electronics and system-level benefits 131 Disadvantages of the switched-reluctance system 132 Torque ripple 133 Acoustic noise 133 3 Stepper-motor drives 134 Stepping-motor principles 134 The permanent-magnet motor 135 The VR motor 135 The hybrid motor 135 Stepping-motor drive circuits (logic modes) 136 Unipolar switching 137 Bipolar switching 137 High-speed stepping -- L/R drives 139 Chopper drives 139 Bilevel drives 139 Application notes 139 Effect of inertia 139 Resonance 139 Special products 140 Stepper/encoders 140 Space-rated steppers 140 Fuel-control actuators 140 6 Practical drives 141 1 General 141 Digital input 143 Programmability 143 Typical specification 143 Digital output 143 Programmability 143 Typical specification 143 Analogue input 143 Programmability 143 Typical specification 144 Analogue output 144 Programmability 144 Typical specification 144 2 D.C. drives 145 The technology 145 Drive selection 145 Technical specifications and ratings 148 Drive set up and commissioning 148 Autotune 148 PC-based commissioning tools -- MentorSoft 148 Performance 148 Speed and current-loop response 148 Typical applications 149 Low-power analogue D.C. drives 149 vii Contents vii The 4Q2 D.C. drive 149 Cheetah--Puma--Lynx 149 3 A.C. drives 151 Features common to all A.C. drives 151 Power terminal layout 151 Control terminal layout 151 Wiring precautions to prevent electromagnetic compatibility (EMC) issues 153 Open-loop inverters 153 Specifications and ratings 153 Features and options 153 Methods of control 156 Performance of the Commander SE open-loop drive 156 Typical applications 157 The universal A.C. drive 157 The concept of a universal drive 157 Unidrive option modules 158 Open-loop operation 159 Closed-loop operation 159 Servo operation 160 Regeneration mode 162 High-performance servodrives 163 Performance 166 Summary of practical advantages of SLM technology 168 Applications 169 4 Soft-start A.C. motor control 169 Conventional starting 169 Direct-on-line starting (DOL) 169 Star-delta starting 169 Auto-transformer starting 170 Disadvantages of conventional starting 170 Electronic soft start 171 Typical applications 171 5 Application boards and software 172 Applications module 172 Software commissioning tools 173 Communications modes 173 Drive set-up wizard 173 Commissioning screen 174 Monitoring screen 174 Parameter list 174 7 Position and motion-control systems 175 1 General 175 2 Basics of motion control 177 3 Typical motion functions 180 Position lock -- electronic gearbox 180 Direct positional lock 180 Ramped nonrigid lock 180 Ramped rigid lock 180 Simple single-axis positioning 182 CAM functions 182 Multiaxis positioning 183 4 Programmability 187 5 Summary 188 8 Communications systems 189 1 Introduction 189 Drive set up 190 Drive control 191 Summary 191 2 Network basics 191 Physical layer 192 Network cables and connectors 192 Interface circuits 192 Data encoding 192 Network topology 193 Data-link layer 194 Framing 194 Data model 194 Media access control 194 Error handling 195 Conclusions 195 Application layer 195 Device profile 195 3 Simple fieldbus systems 196 Modbus 196 Control Techniques' protocol 196 4 Fieldbus systems 197 Requirements for drive applications 197 Physical layer 197 Error detection 197 Dynamic performance 197 General message services 197 Centralised versus distributed intelligence 197 Profibus DP 197 Interbus-S 198 CAN 198 DeviceNet 198 CANopen 198 CTNet 198 9 Supply harmonics due to drives 199 1 Overview 199 2 Regulations 200 Regulations for installations 200 Regulations and standards for equipment 200 3 Harmonic generation within variable-speed drives 201 A.C. drives 201 D.C. drives 203 Effect of loading 203 4 The effects of harmonics 203 5 Calculation of harmonics 204 Individual drives -- D.C. 204 Individual drives -- A.C. 205 Systems 205 Isolated generators 206 6 Remedial techniques 206 Connect the equipment to a point with a high fault level (low impedance) 207 Use three-phase drives where possible 207 Use additional inductance 207 Additional A.C. supply-line inductance 207 Additional D.C. inductance 207 Use a higher pulse number (12 pulse or higher) 207 Use a drive with an active input stage 211 Use a harmonic filter 211 10 Electromagnetic compatibility (EMC) 213 1 Introduction 213 General 213 Principles of EMC 214 viii Contentsviii EMC regulations 214 2 Regulations and standards 214 Regulations 214 Standards 215 3 EMC behaviour of variable-speed drives 215 Immunity 215 Low-frequency emission 216 High-frequency emission 216 4 Installation rules 217 EMC risk assessment 217 Basic rules 217 Segregation 217 Control of return paths, minimising loop areas 217 Earthing 218 Simple precautions and fixes 219 Full precautions 219 5 Theoretical background 220 Emission modes 220 Principles of input filters 221 Screened motor cables 222 Ferrite ring suppressors 222 Filter earth leakage current 222 Filter magnetic saturation 222 6 Additional guidance on cable screening for sensitive circuits 223 Cable screening action 223 Cable screen connections 223 Recommended cable arrangements 225 11 Systems design 227 1 General 228 2 Design matrix 228 3 Dynamic/resistive braking 228 General 228 D.C. motor braking 228 Example calculation of a brake resistor of a D.C. motor 231 A.C. regeneration and braking 231 Example calculation of a brake resistor of a PWM A.C. induction motor drive system 232 4 Fusing 233 General 233 Protection of mains-drive and drive-motor cabling 233 Protection of drive components 233 5 Motor overtemperature protection 234 General 234 Overtemperature protection of a converter-fed motor 235 What can be used 235 What cannot be used 235 6 A.C. drive motor cabling 236 General 236 Closed loop -- induction motor 236 Cable resistance 236 Cable-charging currents 236 Closed loop -- PM servomotor 237 Cable resistance 237 Cable-charging currents 237 Open-loop current control--induction motor 237 Cable resistance 237 Cable-charging currents 237 Limits to cable length 237 Example 240 Output chokes for long motor cable applications 240 General 240 Principles 240 Calculations 240 Example 241 Position of chokes in multiple motor configurations 241 Typical recommended cable size 242 7 Power supply considerations 243 High or low line voltage 243 Supply frequency variations 243 Supply impedance/fault level 243 Low supply impedance 243 High supply impedance 243 Multiple drive installations 244 8 Thermal design of enclosures 244 General 244 Calculating the size of a sealed enclosure 244 Example 244 Calculating the air flow in a ventilated enclosure 245 Example 245 9 Installation and maintenance of standard motors and electronic equipment 246 Motors 246 General 246 Storage 246 Installation 246 Maintenance guide 247 Brush gear maintenance 247 Electronic equipment 248 General 248 Siting of equipment 248 Ventilator systems and filters 249 Condensation and humidity 249 Fuses 249 10 Common D.C. bus configuration of A.C. drives 250 General 250 A simple bulk uncontrolled rectifier 250 Using the mains supply converter in one drive to supply all drives from its D.C. link 252 Effectively hard paralleling of all drive input rectifiers 252 A bulk four-quadrant controlled rectifier feeding the D.C. bus 252 A bulk four-quadrant PWM converter feeding the D.C. bus 253 Note on EMC filters for common D.C. bus systems 254 11 Mechanical vibration, critical speed and torsional dynamics 255 General 255 Example 255 Causes of shaft vibrations independent of variable-speed drives 255 Subsynchronous vibrations 256 Synchronous vibrations 256 Super-synchronous vibrations 256 Critical speeds 256 Applications where torque ripple excites a resonance in the mechanical system 256 High-performance closed-loop applications 257 ix Contents ix Limits to dynamic performance 257 System control-loop instability 257 Measures for reducing vibration 257 12 Applications 259 1 Typical load characteristics and ratings 259 Metals industries 260 Plastics 260 Rubber 260 Chemical 261 Materials handling 261 Lift, hoist and crane 261 Concrete pipe manufacture 261 Fans and blowers 262 Pumps 262 Paper and tissue 262 Printing 262 Packaging 263 Engineering industries 263 Wire and cable 263 Hydraulics 263 Electric motors and alternators 264 Textiles 264 Foods, biscuit and confection 264 2 Techniques common to many applications 264 Special D.C. loads 264 Traction motor field control 264 Battery charging 265 Electrolytic processes 265 Electric heating and temperature control 265 Digital slaving 266 General 266 Drive slaving techniques 266 Principle of digital speed/position following 266 The digital speed/position controller 267 Load sharing 268 General 268 D.C. thyristor converter-fed system 269 A.C. inverter-fed systems 271 High-frequency inverters 272 General 272 Frequency control of A.C. induction motors 272 High-frequency purpose-designed motors 273 High-frequency inverters 274 High-frequency applications 274 Centre winders 275 General 275 Speed or torque control 276 Taper tension 276 Constant torque and field weakening 276 Power requirements for centre- driven winders 277 Inertia compensation 277 Loss compensation 278 Flux compensation 278 Drive selection--limiting parameters 278 Sectional drive systems 278 General 278 Theory of operation 281 Using an IEC61131-3 programming tool to configure a sectional drive line 284 Energy saving 284 General 284 Centrifugal pumps 285 Centrifugal fans and compressors 288 3 Application principles/examples 288 Cranes and hoists 289 General 289 Planning an installation 289 Slewing control 289 Crane refurbishment for a Norwegian steel wire rope maker 290 Elevators and lifts 291 Lift system description 291 Speed profile generation 292 Load weighing devices 292 Metals and metal forming 292 Winding, crimping and precise cutting 292 Roll feed line 295 Wire and cable manufacture 296 Four-quadrant D.C. drives for a bar mill 296 Wire-drawing machine 296 Paper manufacturing 297 General 297 Sectional drives 297 Loads and load sharing 298 Control and instrumentation 299 Winder drives 300 Brake generator power and energy 301 Unwind brake generator control 302 Coating machines 302 Paper-slitting machine 303 Paper board machine 303 Building materials 304 Brick-handling line 304 Roofing-tile manufacturing plant 305 Textiles 307 Fabric-dyeing machine 307 Quilting machine 308 Plastics extrusion 308 General 308 Basic extruder components 310 Overall extruder performance 310 Energy considerations 310 Motors and controls 311 Food 312 Control of hammermills in animal feed production 312 HVAC 313 Air conditioning for driver and vehicle licensing agency 313 Air-handling units at Oxford Brookes University students' union 313 Steel 314 Main mill drives 314 Auxiliary drives 314 Chemical 315 Enamel painting of fluorescent tubes 315 Marine applications 316 Cable laying 316 Pipe laying 318 Control of lock gates and sluices 319 Printing 320 Real-time registration and shaftless web tensioning control 320 x Contentsx Offset printing presses 321 Stage scenery -- film and theatre 322 James Bond film stunts 322 Controlling acoustics 323 Exhibition focal point -- the Control Techniques' orchestra 323 Rock concert 325 Millennium Dome aerial ballet 326 Appendix A Standards for drives 329 A1 IEC (international) standards 330 Planned future IEC61800 standards 332 A2 CENELEC (EC) standards 332 A3 British standards 334 A4 IEEE (USA) standards 335 A5 UL (Underwriters' Laboratories, USA) standards 335 A6 Other standards 335 Electricity Association, UK 335 EIA/TIA (previously RS) 335 ANSI 335 Appendix B Symbols and formulae 336 B1 SI units and symbols 336 SI base units 337 Decimal multiples and submultiples 337 Derived units 337 Geometrical units 337 Time-related units 337 Mechanical units 337 B2 Electrical formulae 338 Electrical quantities 338 A.C. three-phase (assuming balanced symmetrical waveform) 338 A.C. single phase 338 Three-phase induction motors 338 Loads (phase values) 338 Impedance 338 A.C. vector and impedance diagrams 338 E.m.f., energy transfer 339 Mean and r.m.s. values, waveform 340 Principles 340 Mean D.C. value 340 R.m.s. value 341 Other waveforms 341 Form factor 341 B3 Mechanical formulae 342 Laws of motion 342 Linear motion 342 Rotational or angular motion 343 Relationship between linear and angular motion 343 The effect of gearing 344 Friction and losses 344 Fluid flow 345 B4 Worked examples of typical mechanical loads 346 Conveyor 346 Data 346 Method 346 Calculate speeds and gearing ratio 346 Load, force and torque 346 Power ratings for the motor and drive 347 Inclined conveyor 348 Hoist 348 Data 348 Velocity ratio (VR) 348 Speed and acceleration of the hook 348 Lifting force and torque to accelerate from rest to full speed 348 Lifting force and torque to maintain full speed 349 Required motor power rating 349 Drive module power rating 349 Screw-feed loads 349 Appendix C Tables 351 C1 Mechanical conversion tables 351 Length 351 Area 352 Volume 352 Mass 353 Energy 353 Inertia 353 Torque 354 Force 354 Power 354 C2 General conversion tables 354 Length 354 Area 354 Volume 355 Mass 355 Force and weight 355 Pressure and stress 355 Velocity (linear) 355 Velocity (angular) 355 Torque 355 Energy 355 Power 355 Moment of inertia 356 Temperature 356 Flow 356 Torque 356 Force 356 Moment of inertia 356 Linear acceleration 356 C3 Power/torque/speed nomogram 357 Appendix D World industrial electricity supplies (` 1 kV) 358 Appendix E Bibliography and further reading 363 Index 365 xiContents xi . Introduction 33 W. Drury (Ed.) The Control Techniques Drives and Controls Handbook Temperature 33 Altitude 34 Power supply system 34 Noise and vibration 34 General. terms 101 4 Drive control 103 1 General 103 The ideal control system 103 Open-loop control 103 Closed-loop control 104 Criteria for assessing the performance