Electric Drives and Electromechanical Systems

309 Pages·2005·2.85 MB·English

by  Richard Crowder

Electric Drives and Electromechanical Systems
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Electric Drives and
Electromechanical Systems

Richard Crowder

Amsterdam (cid:404) Boston (cid:404) Heidelberg (cid:404) London (cid:404) New York (cid:404) Oxford
Paris (cid:404) San Diego (cid:404) San Franciso (cid:404) Singapore (cid:404) Sydney (cid:404) Tokyo

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First edition 2006

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ISBN–13: 978-0-7506-6740-1
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06 07 08 09 10 10 9 8 7 6 5 4 3 2 1
Contents
Preface xi
Listofprincipalsymbols xiii
1 Electromechanicalsystems 1
1.1 Principlesofautomation . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Machinetools . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.1 Conventionalmachiningprocesses . . . . . . . . . . . . . 4
1.2.2 Non-conventionalmachining . . . . . . . . . . . . . . . . 7
1.2.3 Machiningcentres . . . . . . . . . . . . . . . . . . . . . 10
1.3 Robots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.3.1 Industrialrobots . . . . . . . . . . . . . . . . . . . . . . 11
1.3.2 Robotichands . . . . . . . . . . . . . . . . . . . . . . . 18
1.3.3 Mobilerobotics . . . . . . . . . . . . . . . . . . . . . . . 23
1.3.4 Leggedrobots. . . . . . . . . . . . . . . . . . . . . . . . 24
1.4 Otherapplications . . . . . . . . . . . . . . . . . . . . . . . . . . 27
1.4.1 Automotiveapplications . . . . . . . . . . . . . . . . . . 27
1.4.2 Aerospaceapplications . . . . . . . . . . . . . . . . . . . 28
1.5 Motion-controlsystems . . . . . . . . . . . . . . . . . . . . . . . 31
1.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2 Analysingadrivesystem 35
2.1 Rotarysystems . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.1.1 Fundamentalrelationships . . . . . . . . . . . . . . . . . 35
2.1.2 Torqueconsiderations . . . . . . . . . . . . . . . . . . . 37
2.1.3 Gearratios . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.1.4 Accelerationwithoutanexternalload . . . . . . . . . . . 40
2.1.5 Accelerationwithanappliedexternalload . . . . . . . . . 41
2.1.6 Acceleratingloadswithvariableinertias . . . . . . . . . . 42
2.2 Linearsystems . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
2.3 Friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.4 Motionprofiles . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.5 Assessmentofamotor-drivesystem . . . . . . . . . . . . . . . . 52
v
vi CONTENTS
2.5.1 Mechanicalcompatibility. . . . . . . . . . . . . . . . . . 52
2.5.2 Electromagneticcompatibility . . . . . . . . . . . . . . . 53
2.5.3 Wiringconsiderations . . . . . . . . . . . . . . . . . . . 55
2.5.4 Supplyconsiderations . . . . . . . . . . . . . . . . . . . 57
2.5.5 Protectionfromtheenvironment . . . . . . . . . . . . . . 61
2.5.6 Drivehazardsandrisk . . . . . . . . . . . . . . . . . . . 62
2.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
3 Powertransmissionandsizing 71
3.1 Gearboxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
3.1.1 Planetarygearbox. . . . . . . . . . . . . . . . . . . . . . 72
3.1.2 Harmonicgearbox . . . . . . . . . . . . . . . . . . . . . 75
3.1.3 Cycloidgearbox . . . . . . . . . . . . . . . . . . . . . . 77
3.2 Leadandballscrews . . . . . . . . . . . . . . . . . . . . . . . . 78
3.3 Beltdrives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.4 Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
3.4.1 Conventionalbearings . . . . . . . . . . . . . . . . . . . 85
3.4.2 Airbearings . . . . . . . . . . . . . . . . . . . . . . . . . 88
3.4.3 Magneticbearings . . . . . . . . . . . . . . . . . . . . . 89
3.5 Couplings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
3.6 Shafts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
3.6.1 Staticbehaviourofshafts . . . . . . . . . . . . . . . . . . 92
3.6.2 Transientbehaviourofshafts . . . . . . . . . . . . . . . . 93
3.7 Lineardrives . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
3.8 Reviewofmotor-drivesizing . . . . . . . . . . . . . . . . . . . . 96
3.8.1 Continuousduty . . . . . . . . . . . . . . . . . . . . . . 98
3.8.2 Intermittentduty . . . . . . . . . . . . . . . . . . . . . . 99
3.8.3 Inabilitytomeetboththespeedandthetorquerequirements 102
3.8.4 Linearmotorsizing . . . . . . . . . . . . . . . . . . . . . 103
3.9 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
4 Velocityandpositiontransducers 107
4.1 Theperformanceofmeasurementsystems . . . . . . . . . . . . . 107
4.1.1 Randomerrors . . . . . . . . . . . . . . . . . . . . . . . 108
4.1.2 Systematicerrors . . . . . . . . . . . . . . . . . . . . . . 111
4.1.3 Digital-systemerrors . . . . . . . . . . . . . . . . . . . . 112
4.1.4 Analogue-digitalanddigital-analogueconversionerrors . 113
4.1.5 Dynamicperformance . . . . . . . . . . . . . . . . . . . 115
4.2 Rotatingvelocitytransducers . . . . . . . . . . . . . . . . . . . . 115
4.2.1 Brushedd.c. tachogenerators . . . . . . . . . . . . . . . . 116
4.2.2 Brushlessd.c. tachogenerators . . . . . . . . . . . . . . . 117
4.2.3 Incrementalsystems . . . . . . . . . . . . . . . . . . . . 117
4.2.4 Electromechanicalpulseencoders . . . . . . . . . . . . . 118
4.3 Positiontransducers . . . . . . . . . . . . . . . . . . . . . . . . . 118
CONTENTS vii
4.3.1 Brushedpotentiometers . . . . . . . . . . . . . . . . . . 119
4.3.2 Linearvariabledifferentialtransformers–LVDT . . . . . 119
4.3.3 Resolvers . . . . . . . . . . . . . . . . . . . . . . . . . . 120
4.3.4 RotaryandlinearInductosyn . . . . . . . . . . . . . . . . 125
4.3.5 Opticalpositionsensors . . . . . . . . . . . . . . . . . . 127
4.4 Applicationofpositionandvelocitytransducers . . . . . . . . . . 131
4.4.1 Mechanicalinstallation . . . . . . . . . . . . . . . . . . . 131
4.4.2 Electricalinterconnection . . . . . . . . . . . . . . . . . 133
4.4.3 Determinationofdatumposition . . . . . . . . . . . . . . 135
4.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
5 Brusheddirect-currentmotors 137
5.1 Reviewofmotortheory . . . . . . . . . . . . . . . . . . . . . . . 137
5.2 Direct-currentmotors . . . . . . . . . . . . . . . . . . . . . . . . 139
5.2.1 Ironless-rotormotors . . . . . . . . . . . . . . . . . . . . 139
5.2.2 Iron-rotormotors . . . . . . . . . . . . . . . . . . . . . . 141
5.2.3 Torquemotors . . . . . . . . . . . . . . . . . . . . . . . 141
5.2.4 Printed-circuitmotors . . . . . . . . . . . . . . . . . . . 143
5.3 Drivesford.c. brushedmotors . . . . . . . . . . . . . . . . . . . 144
5.3.1 Four-quadrantthyristorconverters . . . . . . . . . . . . . 145
5.3.2 Linearamplifiers . . . . . . . . . . . . . . . . . . . . . . 145
5.3.3 Pulsewidthmodulatedservodrives . . . . . . . . . . . . 148
5.3.4 AnalysisofthebipolarPWMamplifier . . . . . . . . . . 151
5.3.5 PWMamplifiers . . . . . . . . . . . . . . . . . . . . . . 155
5.4 Regeneration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
5.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
6 Brushlessmotorsandcontrollers 169
6.1 Thed.c. brushlessmotor . . . . . . . . . . . . . . . . . . . . . . 172
6.1.1 Torque-speedcharacteristics . . . . . . . . . . . . . . . . 176
6.1.2 Brushlessd.c. motorcontrollers . . . . . . . . . . . . . . 178
6.2 Sinewave-woundbrushlessmotors . . . . . . . . . . . . . . . . . 182
6.2.1 Torquecharacteristics . . . . . . . . . . . . . . . . . . . 183
6.2.2 Voltagecharacteristics . . . . . . . . . . . . . . . . . . . 185
6.2.3 Torque-speedcharacteristics . . . . . . . . . . . . . . . . 185
6.2.4 Controlofsinewave-woundbrushlessmotors . . . . . . . 187
6.3 Linearmotors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
6.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
7 Inductionmotors 191
7.1 Inductionmotorcharacteristics . . . . . . . . . . . . . . . . . . . 192
7.2 Scalarcontrol . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
7.3 Vectorcontrol . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
7.3.1 Vectorcontrolprinciples . . . . . . . . . . . . . . . . . . 203
viii CONTENTS
7.3.2 Implementationofvectorcontrol. . . . . . . . . . . . . . 207
7.3.3 Vectorcontrolusingsensors . . . . . . . . . . . . . . . . 208
7.3.4 Sensorlessvectorcontrol . . . . . . . . . . . . . . . . . . 211
7.4 Matrixconverter. . . . . . . . . . . . . . . . . . . . . . . . . . . 211
7.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
8 Steppermotors 215
8.1 Principlesofstepper-motoroperation . . . . . . . . . . . . . . . 216
8.1.1 Multistackvariable-reluctancemotors . . . . . . . . . . . 216
8.1.2 Single-stackvariable-reluctancemotors . . . . . . . . . . 218
8.1.3 Hybridsteppermotors . . . . . . . . . . . . . . . . . . . 218
8.1.4 Linearsteppermotor . . . . . . . . . . . . . . . . . . . . 221
8.1.5 Comparisonofmotortypes . . . . . . . . . . . . . . . . . 222
8.2 Static-positionaccuracy . . . . . . . . . . . . . . . . . . . . . . . 223
8.3 Torque-speedcharacteristics . . . . . . . . . . . . . . . . . . . . 225
8.4 Controlofsteppermotors . . . . . . . . . . . . . . . . . . . . . . 226
8.4.1 Open-loopcontrol . . . . . . . . . . . . . . . . . . . . . 228
8.4.2 Translatorsanddrivecircuits . . . . . . . . . . . . . . . . 229
8.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
9 Relatedmotorsandactuators 235
9.1 Voicecoils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
9.2 Limited-angletorquemotors . . . . . . . . . . . . . . . . . . . . 237
9.3 Piezoelectricmotors. . . . . . . . . . . . . . . . . . . . . . . . . 239
9.4 Switchedreluctancemotors . . . . . . . . . . . . . . . . . . . . . 240
9.5 Shape-memoryalloy . . . . . . . . . . . . . . . . . . . . . . . . 245
9.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
10 Controllersforautomation 247
10.1 Servocontrol . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
10.1.1 Digitalcontrollers . . . . . . . . . . . . . . . . . . . . . 253
10.1.2 Advancedcontrolsystems . . . . . . . . . . . . . . . . . 257
10.1.3 Digitalsignalprocessors . . . . . . . . . . . . . . . . . . 257
10.2 Motioncontrollers . . . . . . . . . . . . . . . . . . . . . . . . . 259
10.3 Programmablelogiccontrollers . . . . . . . . . . . . . . . . . . . 262
10.3.1 Combinational-logicprogramming . . . . . . . . . . . . . 265
10.3.2 Sequential-logicprogramming . . . . . . . . . . . . . . . 267
10.4 Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
10.4.1 Networkarchitecture . . . . . . . . . . . . . . . . . . . . 274
10.4.2 Industrialnetworking . . . . . . . . . . . . . . . . . . . . 276
10.4.3 SCADA . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
10.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
UnitsandConversionFactors 281
CONTENTS ix
Bibliography 285
Index 289