Variable Speed AC Drives with Inverter Output Filters

The advance of variable speed drives systems (VSDs) engineering highlights the need of specific technical guidance provision by electrical machines and drives manufacturers, so that such applications can be properly designed to present advantages in terms of both energy efficiency and expenditure. This book presents problems and solutions related to inverter-fed electrical motors. Practically orientated, the book describes the reasons, theory and analysis of those problems. Various solutions for individual problems are presented together with the complete design process, modelling and simulation examples with MATLAB/Simulink on the companion website. A key focus of Variable Speed AC Drives with Inverter Output Filters is to examine the state variables estimation and motor control structures which have to be modified according to the used solution (filter). In most control systems the structure and parameters are taken into account to make it possible for precise control of the motor. This methodology is able to include modifications and extensions depending on specific control and estimation structures. Highly accessible, this is an invaluable resource for practising R&D engineers in drive companies, power electronics & control engineers and manufacturers of electrical drives. Senior undergraduate and postgraduate students in electronics and control engineering will also find it of value.

Table of Contents:
Foreword xi Acknowledgments xiii About the Authors xiv Nomenclature xvi 1 Introduction to Electric Drives with LC Filters 1 1.1 Preliminary Remarks 1 1.2 General Overview of AC Drives with Inverter Output Filters 2 1.3 Book Overview 4 1.4 Remarks on Simulation Examples 5 References 6 2 Problems with AC Drives and Voltage Source Inverter Supply Effects 9 2.1 Effects Related to Common Mode Voltage 9 2.1.1 Capacitive Bearing Current 15 2.1.2 Electrical Discharge Machining Current 15 2.1.3 Circulating Bearing Current 15 2.1.4 Rotor Grounding Current 17 2.1.5 Dominant Bearing Current 17 2.2 Determination of the Induction Motor CM Parameters 18 2.3 Prevention of Common Mode Current: Passive Methods 20 2.3.1 Decreasing the Inverter Switching Frequency 20 2.3.2 Common Mode Choke 21 2.3.3 Integrated Common Mode and Differential Mode Choke 23 2.3.4 Common Mode Transformer 25 2.3.5 Machine Construction and Bearing Protection Rings 26 2.4 Active Systems for Reducing the CM Current 27 2.5 Common Mode Current Reduction by PWM Algorithm Modifications 28 2.5.1 Three Nonparity Active Vectors 30 2.5.2 Three Active Vector Modulation 32 2.5.3 Active Zero Voltage Control 32 2.5.4 Space Vector Modulation with One Zero Vector 36 2.6 Simulation Examples 39 2.6.1 Model of Induction Motor Drive with PWM Inverter and cmv 39 2.6.2 PWM Algorithms for Reduction of cmv 44 2.7 Summary 46 References 46 3 Model of AC Induction Machine 49 3.1 Introduction 49 3.1.1 T‐Model of Induction Machine 50 3.2 Inverse‐Γ Model of Induction Machine 53 3.3 Per‐Unit System 54 3.4 Machine Parameters 56 3.5 Simulation Examples 59 References 63 4 Inverter Output Filters 65 4.1 Structures and Fundamentals of Operations 65 4.2 Output Filter Model 71 4.3 Design of Inverter Output Filters 74 4.3.1 Sinusoidal Filter 74 4.3.2 Common Mode Filter 80 4.4 dV/dt Filter 83 4.5 Motor Choke 85 4.6 Simulation Examples 86 4.6.1 Inverter with LC Filter 86 4.6.2 Inverter with Common Mode and Differential Mode Filter 90 4.7 Summary 95 References 96 5 Estimation of the State Variables in the Drive with LC Filter 97 5.1 Introduction 97 5.2 The State Observer with LC Filter Simulator 99 5.3 Speed Observer with Simplified Model of Disturbances 103 5.4 Speed Observer with Extended Model of Disturbances 106 5.5 Speed Observer with Complete Model of Disturbances 107 5.6 Speed Observer Operating for Rotating Coordinates 109 5.7 Speed Observer Based on Voltage Model of Induction Motor 114 5.8 Speed Observer with Dual Model of Stator Circuit 122 5.9 Adaptive Speed Observer 125 5.10 Luenberger Flux Observer 129 5.11 Simulation Examples 130 5.11.1 Model of the State Observer with LC Filter Simulator 130 5.11.2 Model of Speed Observer with Simplified Model of Disturbances 133 5.11.3 Model of Rotor Flux Luenberger Observer 136 5.12 Summary 138 References 138 6 Control of Induction Motor Drives with LC Filters 141 6.1 Introduction 141 6.2 A Sinusoidal Filter as the Control Object 141 6.3 Field Oriented Control 143 6.4 Nonlinear Field Oriented Control 148 6.5 Multiscalar Control 156 6.5.1 Main Control System of the Motor State Variables 157 6.5.2 Subordinated Control System of the Sinusoidal Filter State Variables 160 6.6 Electric Drive with Load‐Angle Control 166 6.7 Direct Torque Control with Space Vector Pulse Width Modulation 178 6.8 Simulation Examples 186 6.8.1 Induction Motor Multiscalar Control with Multiloop Control of LC Filter 186 6.8.2 Inverter with LC Filter and LR Load with Closed‐Loop Control 194 6.9 Summary 198 References 198 7 Current Control of the Induction Motor 201 7.1 Introduction 201 7.2 Current Controller 203 7.2.1 Predictive Object Model 207 7.2.2 Costs Function 208 7.2.3 Predictive Controller 208 7.3 Investigations 208 7.4 Simulation Examples of Induction Motor with Motor Choke and Predictive Control 210 7.5 Summary and Conclusions 216 References 217 8 Diagnostics of the Motor and Mechanical Side Faults 218 8.1 Introduction 218 8.2 Drive Diagnosis Using Motor Torque Analysis 218 8.3 Diagnosis of Rotor Faults in Closed‐Loop Control 233 8.4 Simulation Examples of Induction Motor with Inverter Output Filter and Load Torque Estimation 235 8.5 Conclusions 239 References 239 9 Multiphase Drive with Induction Motor and an LC Filter 241 9.1 Introduction 241 9.2 Model of a Five‐Phase Machine 243 9.3 Model of a Five‐Phase LC Filter 246 9.4 Five‐Phase Voltage Source Inverter 247 9.5 Control of Five‐Phase Induction Motor with an LC Filter 253 9.6 Speed and Flux Observer 255 9.7 Induction Motor and an LC Filter for Five‐Phase Drive 257 9.8 Investigations of Five‐Phase Sensorless Drive with an LC Filter 257 9.9 FOC Structure in the Case of Combination of Fundamental and Third Harmonic Currents 262 9.10 Simulation Examples of Five‐Phase Induction Motor with a PWM Inverter 266 References 269 10 General Summary, Remarks, and Conclusion 271 Appendix A Synchronous Sampling of Inverter Output Current 273 References 276 Appendix B Examples of LC Filter Design 277 B.1 Introduction 277 Appendix C Equations of Transformation 282 References 285 Appendix D Data of the Motors Used in Simulations and Experiments 286 Appendix E Adaptive Backstepping Observer 289 Marcin Morawiec E.1 Introduction 289 E.2 LC Filter and Extended Induction Machine Mathematical Models 290 E.3 Backstepping Speed Observer 292 E.4 Stability Analysis of the Backstepping Speed Observer 298 E.5 Investigations 304 E.6 Conclusions 305 References 307 Appendix F Significant Variables and Functions in Simulation Files 308 Index 311