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Magnetic Bearings and Bearingless Drives

Book Description

The application of bearingless drives is emerging as an important technique in the areas of high-speed machinery and motion-control, and this book aims to provide a thorough grounding in the principles behind this cutting-edge technology. Basic principles are described in detail with practical examples to aid understanding, and the different types of bearingless drives are introduced, along with coverage of test machines and applications.

Aimed at practising electrical and mechanical engineers and advanced students, Magnetic Bearings and Bearingless Drives provides an essential guide to an area of engineering previously only fully covered by large numbers of academic papers.

· Unique and comprehensive coverage of a cutting-edge subject for electrical and mechanical engineers
· A reference text and survey for designers, manufacturers and users of high-speed motors, generators and electrical drive systems
· Examines the basic principles behind magnetic bearings, with key technologies and applications illustrated through examples and case studies

Table of Contents

  1. Cover image
  2. Title page
  3. Table of Contents
  4. Copyright
  5. List of Contributors
  6. Foreword
  7. Preface
  8. Acknowledgements
  9. Chapter 1: Introduction
    1. 1.1 Magnetic bearing and motor drive
    2. 1.2 Bearingless drives
    3. 1.3 Definition and related technologies
    4. 1.4 Early developments
    5. 1.5 Bearingless structures
    6. 1.6 Comparisons
    7. 1.7 Winding structures
    8. 1.8 Applications
  10. Chapter 2: Electro-magnetics and mathematical model of magnetic bearings
    1. 2.1 Electro-mechanical structure and operating principles
    2. 2.2 Electric equivalent circuit and inductance
    3. 2.3 Stored magnetic energy and force
    4. 2.4 Radial magnetic bearing
    5. 2.5 Unbalance pull force
    6. 2.6 Block diagram and mechanical system
  11. Chapter 3: Magnetic bearing controllers
    1. 3.1 Design principles in one-axis magnetic suspension
    2. 3.2 Adjustment of PID gains
    3. 3.3 Interference in two perpendicular axes
    4. 3.4 Unbalance force and elimination
    5. 3.5 Eccentric displacement
    6. 3.6 Synchronized displacement suppression
  12. Chapter 4: Mechanical dynamics
    1. 4.1 Two-axis system
    2. 4.2 Four-axis and five-axis systems
    3. 4.3 Thrust magnetic bearing and requirement of five-axis suspension
  13. Chapter 5: Power electronic circuits for magnetic bearings
    1. 5.1 Structure and principles of power electronic circuits
    2. 5.2 PWM operation
    3. 5.3 Current feedback
    4. 5.4 Current driver operating area
    5. 5.5 Power devices and gate drive circuits
  14. Chapter 6: Primitive model and control strategy of bearingless motors
    1. 6.1 Principles of radial force generation
    2. 6.2 Two-pole bearingless motor
    3. 6.3 MMF and permeance
    4. 6.4 Magnetic potential and flux distribution
    5. 6.5 Inductance matrix
    6. 6.6 Radial force and current
    7. 6.7 The dc excitation of the primitive bearingless motor
    8. 6.8 AC excitation and revolving magnetic field
    9. 6.9 Inductance measurements
  15. Chapter 7: Analysis in rotational coordinates and magnetic suspension strategy for bearingless drives with 2-pole and 4-pole windings
    1. 7.1 Vector control theory of electrical motors
    2. 7.2 Coordinate transformation and torque regulation
    3. 7.3 Vector control theory in bearingless motors
    4. 7.4 Coordinate transformation from dc to ac bearingless machines
    5. 7.5 System block diagrams of bearingless machines
  16. Chapter 8: Field orientation, VA requirement and magnetic saturation
    1. 8.1 Misalignment of field orientation
    2. 8.2 VA requirement
    3. 8.3 Magnetic saturation
  17. Chapter 9: Cylindrical permanent magnet synchronous bearingless motors
    1. 9.1 Structure of surface permanent magnet (SPM) rotor
    2. 9.2 Radial suspension force and suspension winding current
    3. 9.3 Equations of voltage and current
    4. 9.4 Guideline for permanent magnet thickness and airgap length
    5. 9.5 Irreversible permanent magnet demagnetization and MMF limitations of stator windings
    6. 9.6 Control system configuration
  18. Chapter 10: Inset types of permanent magnet bearingless motor
    1. 10.1 Structure and features of an inset type of permanent magnet rotor
    2. 10.2 Mutual interference between radial suspension forces
    3. 10.3 Rotor position control strategy
    4. 10.4 Identification of suspension force parameters
  19. Chapter 11: Buried permanent magnet bearingless motors
    1. 11.1 BPM rotor structures
    2. 11.2 Suspension force for unity current and permanent magnet demagnetization
    3. 11.3 Rotor position control strategy
  20. Chapter 12: Synchronous reluctance bearingless motors
    1. 12.1 Torque characteristics
    2. 12.2 Radial force characteristics
    3. 12.3 Drive systems
  21. Chapter 13: Bearingless induction motors
    1. 13.1 Rotor structure and suspension force
    2. 13.2 Indirect type drives
    3. 13.3 Direct type drives
    4. 13.4 Two-pole motor drive
  22. Chapter 14: Homopolar, hybrid and consequent-pole bearingless motors
    1. 14.1 Structures and principles
    2. 14.2 Number of poles
    3. 14.3 Drive systems
  23. Chapter 15: Switched reluctance bearingless motors
    1. 15.1 Configuration of stator windings and principles of suspension force generation
    2. 15.2 Derivation of inductances
    3. 15.3 Assumption and calculation of permeances
    4. 15.4 Theoretical formulae of suspension force and torque
    5. 15.5 A drive system
    6. 15.6 A feed-forward compensator for vibration reduction considering magnetic attraction force
  24. Chapter 16: Winding arrangement variations
    1. 16.1 Modified radial magnetic bearings [1,2]
    2. 16.2 Modified motors [3–5]
    3. 16.3 p-Pole and (p ± 2)-pole windings [9–11]
  25. Chapter 17: Mechanical structure and position regulation
    1. 17.1 Mechanical structure
    2. 17.2 Axial gap bearingless motors
  26. Chapter 18: Displacement sensors and sensorless operation
    1. 18.1 Principles of displacement sensor
    2. 18.2 Improvements in sensitivity
    3. 18.3 Inductive and eddy current sensors
    4. 18.4 Sensorless bearingless motor
  27. Chapter 19: Controllers and power electronics
    1. 19.1 Structure of digital controllers
    2. 19.2 Discrete-time systems of PID controllers with the z-transform
  28. Chapter 20: Design procedure and examples
    1. 20.1 An induction type bearingless motor [1–4]
    2. 20.2 A permanent magnet type bearingless motor [5,6]
  29. Chapter 21: Applications and test machines
    1. 21.1 Canned pumps and drives [1–4]
    2. 21.2 Compact pumps, bubble bed reactor
    3. 21.3 Spindle motor and semiconductor processing
  30. Index