Mechanical Design and Manufacturing of Electric Motors

Cover
Half Title
Title Page
Copyright Page
Dedication
Table of Contents
Preface (2[sup(nd)] Edition)
Preface (1[sup(st)] Edition)
Author
List of Abbreviations
Chapter 1 Introduction to Electric Motors
1.1 History of Electric Machines
1.2 Motor Design Characteristics
1.2.1 Motor Torque
1.2.1.1 Static and Dynamic Torque
1.2.1.2 Motor Torque in Motor-Load System
1.2.1.3 Continuous Torque
1.2.1.4 Peak Torque
1.2.1.5 RMS Torque
1.2.1.6 Stall Torque
1.2.1.7 Cogging Torque and Reduction Methods
1.2.1.8 Torque Ripple
1.2.2 Motor Speed
1.2.2.1 Continuous Speed
1.2.2.2 Peak Speed
1.2.2.3 Speed Ripple
1.2.3 Torque Density
1.2.4 Motor Power and Power Factor
1.2.5 Torque–Speed Characteristics
1.2.6 Mechanical Resonance and Resonant Frequency
1.2.7 Load-to-Motor Inertia Ratio
1.2.8 Duty Cycle
1.2.9 Motor Efficiency
1.2.9.1 Definition of Motor Efficiency
1.2.9.2 IEC Standards on Efficiency Classes of AC
Electric Motors
1.2.10 Motor Insulation
1.2.11 Motor Operation Reliability
1.3 Classifications of Electric Motors
1.3.1 DC and AC Motors
1.3.2 Single-Phase and Three-Phase Motors
1.3.3 Induction and PM Motors
1.3.4 Synchronous and Asynchronous Motors
1.3.5 Servo and Stepper Motors
1.3.6 Gear Drive and Direct Drive Motors
1.3.7 Brush and Brushless Motors
1.3.8 Reluctance Motors
1.3.9 Radial Flux and Axial Flux Motors
1.3.10 Rotary and Linear Motors
1.3.11 Open and Enclosed Motors
1.3.12 Housed and Frameless Motors
1.3.13 Internal Rotor Motor and External Rotor Motor
1.3.14 Specialty Electric Motors
1.3.14.1 Explosion Proof Motor and Flame Proof Motor
1.3.14.2 Submersible Motor
1.3.14.3 Ultrahigh-Speed Motor
1.3.14.4 Motor Operating under Vacuum Environment
1.3.14.5 Motor Operating under Nuclear Radiation Environment
1.3.14.6 Piezoelectric Motor
1.3.15 Motor Classification According to Power Rating
1.4 Motor Design and Operation Parameters
1.4.1 Back EMF Constant, K[sub(e)]
1.4.2 Torque Constant, K[sub(t)]
1.4.3 Velocity Constant, K[sub(v)]
1.4.4 Motor Constant, K[sub(m)]
1.4.5 Mechanical Time Constant, τ[sub(m)]
1.4.6 Electrical Time Constant, τ[sub(e)]
1.4.7 Thermal Time Constant, τ[sub(th)]
1.4.8 Viscous Damping, K[sub(vd)]
1.5 Sizing Equations
1.6 Motor Design Process and Considerations
1.6.1 Design Process
1.6.2 Design Integration
1.6.3 Mechatronics
1.6.4 Temperature Effect on Motor Performance
1.7 Motor Failure Modes
1.8 IP Code
References
Chapter 2 Rotor Design
2.1 Rotor in Induction Motor
2.1.1 Wound Rotor
2.1.2 Squirrel Cage Rotor
2.1.2.1 Factors Affecting Resistance of Squirrel Cage Rotor
2.1.2.2 Double-Cage Rotor
2.1.2.3 Casting Squirrel Cage Rotor
2.1.2.4 Skin Effect
2.1.3 Induction Motor Design Types and Their Performing Characteristics
2.2 Permanent Magnet Rotor
2.2.1 Discovery of Phenomenon of Magnetism
2.2.2 Permanent Magnet Characteristics
2.2.3 Permanent Magnet Materials
2.2.3.1 Ferrite Permanent Magnets
2.2.3.2 Rare Earth Permanent Magnets
2.2.3.3 New Developments of Alternative PMs and Reductions of Reliance on Rare Earths
2.2.4 Magnetization
2.2.5 Factors Causing Demagnetization
2.2.6 Maximum Operating Temperature
2.2.7 Permanent Magnet Mounting and Retention Methods
2.2.8 Ring Magnets
2.2.9 Corrosion Protection of Permanent Magnets
2.3 Rotor Manufacturing Process
2.3.1 Lamination Materials
2.3.2 Lamination Cutting
2.3.3 Lamination Surface Insulation
2.3.4 Lamination Annealing
2.3.5 Lamination Stacking
2.3.6 Rotor Casting for Squirrel Cage Motor
2.3.7 Heat Treatment of Casted Rotor
2.3.8 Rotor Assembly
2.3.9 Rotor Machining and Runout Measurement
2.3.10 Rotor Balancing
2.3.10.1 Type of Unbalance
2.3.10.2 Rotor Balancing Machine
2.3.10.3 Balancing Operation
2.4 Interference Fit
2.4.1 Press Fit
2.4.2 Shrink Fit
2.4.3 Serration Fit
2.4.4 Fit with Knurling
2.4.5 Fit with Adjustable Ringfeder® Locking Devices
2.4.6 Fit with Tolerance Rings
2.5 Stress Analysis of Rotor
2.6 Rotordynamic Analysis
2.6.1 Rotor Inertia
2.6.2 Motor Critical Speed and Resonance
2.7 Rotor Burst Containment Analysis
2.7.1 Rotor Burst Speed
2.7.2 Energy in Rotating Rotor
2.7.2.1 Kinetic Energy in Rotor
2.7.2.2 Elastic Potential Energy in Rotor
2.7.2.3 Ratio of Potential Energy to Kinetic Energy of Rotor
2.7.3 Rotor Burst Containment Design
References
Chapter 3 Shaft Design
3.1 Shaft Materials
3.2 Shaft Loads
3.3 Solid and Hollow Shafts
3.4 Shaft Design Methods
3.4.1 Macaulay’s Method
3.4.2 Area–Moment Method
3.4.3 Castigliano’s Method
3.4.4 Graphical Method
3.5 Engineering Calculations
3.5.1 Normal Stress for Shaft Subjected to Axial Force
3.5.2 Bending Stress for Shaft Subjected to Bending Moment
3.5.3 Torsional Shear Stress and Torsional Deflection
3.5.4 Lateral Deflection of Shaft
3.5.4.1 Lateral Deflection due to Bending Moment
3.5.4.2 Lateral Deflection due to Transverse Force
3.5.4.3 Lateral Deflection due to Shear Force
3.6 Shaft Design Issues
3.6.1 Shaft Design Considerations
3.6.2 Shaft Rigidity
3.6.3 Critical Shaft Speed
3.6.3.1 Shaft with Uniform Diameter
3.6.3.2 Stepped Shaft
3.6.4 Dimensional Tolerance
3.6.5 Shaft Runout
3.6.6 Shaft Eccentricity
3.6.7 Heat Treatment and Shaft Hardness
3.6.8 Shaft Surface Finishing
3.6.9 Shaft Lead
3.6.10 Shaft Seal
3.6.10.1 O-Ring Seal
3.6.10.2 Universal Lip Seal
3.6.10.3 V-Shaped Spring Seal
3.6.10.4 Brush Seal
3.6.10.5 PTFE Seal
3.6.10.6 Spring-Energized Seal
3.6.10.7 Noncontact Seal
3.6.11 Diametrical Fit Types
3.7 Stress Concentration
3.8 Torque Transmission through Mechanical Joints
3.8.1 Keyed Shafts
3.8.1.1 Selection of Key Material
3.8.1.2 Stress Analysis of Key and Keyseat
3.8.1.3 Key Fit
3.8.1.4 Stress Concentration Factors of Keyed Shafts
3.8.2 Spline Shafts
3.8.2.1 Advantages of Spline Shafts
3.8.2.2 Type of Spline
3.8.2.3 Stress Concentration Factors of Spline Shafts
3.8.3 Tapered Shafts
3.9 Fatigue Failure under Alternative Loading
3.10 Shaft Manufacturing Methods
3.10.1 Machined Shaft
3.10.2 Forged Shaft
3.10.3 Welded Hollow Shaft
3.10.4 Shaft Measurement
3.11 Shaft Misalignment between Motor and Driven Machine
3.11.1 Type of Misalignment
3.11.2 Correction of Shaft Misalignment
3.12 Shaft Coupling
3.12.1 Rigid and Semirigid Couplings
3.12.2 Flexible Couplings
3.12.3 Non-Contact Couplings
3.12.4 Oil Shear Couplings
References
Chapter 4 Stator Design
4.1 Stator Lamination
4.1.1 Stator Lamination Material
4.1.2 Stator Lamination Patterns
4.1.2.1 One-Piece Lamination
4.1.2.2 T-Shaped Segmented Lamination
4.1.2.3 Connected Segmented Lamination
4.1.2.4 Two-Section Stator Lamination
4.1.2.5 Stator Lamination Integrated by Individual Teeth and a Yoke Section
4.1.2.6 Slotless Stator Core
4.1.2.7 Slinky Lamination Stator Core
4.2 Magnet Wire
4.2.1 Regular Magnet Wire
4.2.2 Self-Adhesive Magnet Wire
4.2.3 Litz Wire
4.3 Stator Insulation
4.3.1 Injection Molded Plastic Insulation
4.3.2 Slot Liner
4.3.3 Glass Fiber Reinforced Mica Tape
4.3.4 Powder Coating on Stator Core
4.4 Manufacturing Process of a Stator Core
4.4.1 Stator Lamination Cutting
4.4.2 Lamination Fabrication Process
4.4.3 Lamination Annealing
4.4.4 Lamination Stacking
4.4.5 Stator Winding
4.4.5.1 Random Winding by Hand
4.4.5.2 Coil Formation—Distributed Winding
4.4.5.3 Coil Formation—Concentrated Winding
4.4.5.4 Coil Formation—Conductor Bar
4.5 Stator Encapsulation and Impregnation
4.5.1 Encapsulation
4.5.1.1 Encapsulation Materials
4.5.1.2 Encapsulation Process
4.5.2 Varnish Dipping
4.5.3 Trickle Impregnation
4.5.4 Vacuum Pressure Impregnation
4.6 Stator Design Considerations
4.6.1 Cogging Torque
4.6.2 Airgap
4.6.3 Stator Cooling
4.6.4 Robust Design of Stator
4.6.5 Power Density Improvement
4.7 Mechanical Stress of Stator
References
Chapter 5 Motor Frame Design
5.1 Types of Motor Housing Based on Manufacturing Method
5.1.1 Wrapped Housing
5.1.2 Casted Housing
5.1.2.1 Casting Material
5.1.2.2 Casting Process
5.1.2.3 Pressure Casting
5.1.2.4 Heat Treatment
5.1.3 Machined Housing
5.1.4 Stamped Housing
5.1.5 Extruded Motor Housing
5.1.6 Motor Housing with Composite Materials
5.1.7 Motor Housing Fabricated by 3D Printing and Other Additive Manufacturing Processes
5.1.8 Frameless Motor
5.2 Testing Methods of Casted Motor Housing
5.3 Endbell Manufacturing
5.3.1 Casted Endbell
5.3.2 Stamped Endbell
5.3.3 Iron Casting versus Aluminum Casting
5.3.4 Machined Endbell
5.3.5 Forged Endbell
5.4 Motor Assembly Methods
5.4.1 Tie Bar
5.4.2 Tapping at Housing End Surface
5.4.3 Forged Z-Shaped Fastener
5.4.4 Rotary Fasteners
5.4.4.1 Triangle-Base Rotating Fastener
5.4.4.2 Square-Base Rotating Fastener
5.4.4.3 Butterfly-Base Rotating Fastener
5.4.5 Other Types of Fasteners
5.4.5.1 Cylinder-Base Fastener Locked with Retaining Ring
5.4.5.2 Cylinder-Base Fastener with Self-Locking Aperture
5.4.5.3 Fastener Engaged with Housing from Housing Interior
5.4.5.4 Self-Clinching Fastener
5.5 Fastening System Design
5.5.1 Types of Thread Fasteners
5.5.2 Thread Formation
5.5.3 Fastener Preload
5.5.4 Fastener-Tightening Process
5.5.5 Tightening Torque
5.5.6 Thread Engagement and Load Distribution
5.6 Common Types of Electric Motor Enclosures
5.6.1 Open Drip Proof Enclosure
5.6.2 Totally Enclosed Non-Ventilated Enclosure
5.6.3 Totally Enclosed Fan Cooled Enclosure
5.6.4 Totally Enclosed Air over Enclosure
5.6.5 Totally Enclosed Forced Ventilated Enclosure
5.6.6 Totally Enclosed Washdown Enclosure
5.6.7 Explosion Proof Enclosure
5.7 Anticorrosion of Electric Motor and Components
5.7.1 Surface Treatment Methods
5.7.1.1 Electroplating
5.7.1.2 Electroless Plating
5.7.1.3 Physical Vapor Deposition
5.7.1.4 Inorganic Coating
5.7.1.5 Phosphate Coating
5.7.1.6 Electropolishing
5.7.1.7 Nanocoating
5.7.2 Anticorrosion Treatment of Electric Motor
5.7.3 Hydrogen Embrittlement Issues
References
Chapter 6 Motor Bearing
6.1 Bearing Classification
6.1.1 Journal Bearing
6.1.2 Rolling Bearing
6.1.2.1 Ball Bearing
6.1.2.2 Roller Bearing
6.1.3 Noncontact Bearing
6.1.4 Sensor Bearing
6.1.5 Slewing Ring Bearing
6.1.6 Crossed Roller Bearing
6.1.7 Ball Screw
6.2 Bearing Design
6.2.1 Bearing Materials
6.2.2 Bearing Internal Clearances
6.2.3 Allowable Bearing Speed
6.2.4 Bearing Fit
6.2.5 Prevention of Bearing Axial Movement
6.2.6 Bearing Load
6.2.6.1 Bearing Preload Arrangement
6.2.6.2 Radial and Axial Bearing Load
6.2.6.3 Load Distribution
6.3 Bearing Fatigue Life
6.3.1 Calculation of Bearing Fatigue Life
6.3.2 Bearing Failure Probability Distribution
6.3.3 Influence of Unbalance on Bearing Fatigue Life
6.3.4 Influence of Wear on Bearing Fatigue Life
6.3.5 Influence of Internal Radial Clearance on Bearing Fatigue Life
6.4 Bearing Failure Mode
6.4.1 Major Causes of Premature Bearing Failure
6.4.2 Lubricant Selection
6.4.3 Improper Bearing Lubrication
6.4.4 Lubricant Contamination
6.4.5 Grease Leakage
6.4.6 Bearing Sealing and Bearing Shielding
6.4.7 Excessive Load
6.4.8 Internal Radial Interference Condition
6.4.9 Bearing Current
6.4.10 Impact of High Temperature on Bearing Failure
6.4.11 Bearing Failure Associated with Motor Vibration and Overloading
6.4.12 Improper Bearing Installation and Bearing Misalignment
6.4.13 Vertically Mounted Motor
6.5 Bearing Noise
6.6 Bearing Selection
6.6.1 Bearing Type Selection Based on Load
6.6.2 Bearing Type Selection Based on Speed
6.6.3 Selection of Bearing Size
6.7 Bearing Performance Improvement
References
Chapter 7 Motor Brake
7.1 Fundamental Knowledge of Motor Brake
7.1.1 Static and Dynamic Friction
7.1.2 Wear
7.1.3 Kinetic Energy of Rotating Object
7.1.4 Brake Friction Materials
7.1.5 Brake Operation Mode
7.2 Key Design Parameters and Considerations in Brake Design
7.2.1 Braking Torque
7.2.2 Brake Operation Time
7.2.2.1 Definitions of Various Brake Action Time
7.2.2.2 Brake Response Time
7.2.2.3 Actual Braking Time
7.2.2.4 Total Braking Time
7.2.3 Braking Energy for Single Operation and Operation Frequency per Minute
7.2.4 Mean Heat Power
7.2.5 Temperature Rise and Thermal Capacity Rating
7.2.6 Factor of Safety
7.2.7 Brake Backlash
7.2.8 Brake Noise
7.2.9 Maximum Sliding Speed
7.2.10 Reliability and Durability
7.2.11 Brake Operation Cycle
7.2.12 Brake Mounting Arrangement
7.2.13 Brake Size
7.2.14 Brake Integration with Electric Motor
7.2.15 Brake Ingress Protection Rating
7.2.16 Accumulation of Brake Wear Particles
7.3 Classification of Braking System
7.3.1 Electromagnetic Brake
7.3.1.1 Spring-Engaged, Electromagnetically Released Brake
7.3.1.2 Solenoid-Actuated Brake
7.3.1.3 Multiple Disc Friction-Blocking Brake
7.3.1.4 Eddy-Current Brake
7.3.1.5 Magnetic Particle Brake
7.3.1.6 Hysteresis Brake
7.3.1.7 Permanent Magnet Brake
7.3.1.8 Magnetorheological Brake
7.3.1.9 Piezoelectric Brake
7.3.2 Mechanical Brake
7.3.2.1 Compressed Air-Engaged, Spring-Released Brake
7.3.2.2 Spring-Engaged, Hydraulic Pressure Released Brake
7.3.2.3 Pneumatic Brake
7.3.2.4 Hydraulic Brake
7.3.3 Oil Shear Brake
7.3.4 Regenerative Brake
7.4 Brake Failure
7.4.1 Overheating of Mating Friction Surfaces
7.4.2 Excessive Wear on Friction Surfaces
7.4.3 Failure due to Corrosion
7.4.4 Runout of Friction Disc
7.4.5 Thermomechanical Fatigue
7.5 Brake Design and Selection Considerations
7.5.1 Dynamic Stopping Brake or Holding Brake?
7.5.2 AC or DC Brake?
7.5.3 Braking Torque
7.5.4 Overall Inertia of System
7.5.5 Thermal Consideration in Brake Selection
7.5.6 Other Factors Affecting Brake Selection
References
Chapter 8 Servo Feedback Devices and Motor Sensors
8.1 Encoder
8.1.1 Type of Encoder
8.1.1.1 Optical Encoder
8.1.1.2 Magnetic Encoder
8.1.1.3 Capacitive Encoder
8.1.1.4 Inductive Encoder
8.1.2 Absolute and Incremental Encoders
8.1.2.1 Absolute Encoder
8.1.2.2 Incremental Encoder
8.1.3 Resolution of Encoder
8.1.4 Rotary and Linear Encoder
8.1.5 Encoder Mounting
8.2 Resolver
8.2.1 Type of Resolver
8.2.2 Resolver Operating Parameters
8.2.2.1 Resolver Accuracy
8.2.2.2 Input Excitation Frequency, Voltage, and Current
8.2.2.3 Phase Shift
8.2.2.4 Transformation Ratio
8.2.2.5 Winding Impedance
8.2.2.6 Speed Ripple
8.2.2.7 Null Voltage
8.2.3 Resolver Testing
8.2.3.1 Test Equipment and Instruments
8.2.3.2 Determination of Resolver Position Error
8.2.3.3 Measurement of Transformation Ratio
8.2.3.4 Measurement of Phase Shift
8.2.3.5 Measurement of Velocity Ripple
8.2.3.6 Measurement of Resolver Impedance
8.2.3.7 Effect of Cable Length on Resolver Performance
8.2.3.8 Influence of Motor Brake on Resolver Performance
8.2.3.9 Influence of Mechanical Impacts on Resolver
Performance
8.3 Hall Effect Sensor
8.3.1 Linear Sensor
8.3.2 Threshold Sensor
8.4 Proximity Sensor
8.4.1 Inductive Proximity Sensor
8.4.2 Capacitive Proximity Sensor
8.4.3 Ultrasonic Proximity Sensor
8.4.4 Photoelectric Proximity Sensor
8.5 Other Motor Sensors
8.5.1 Force/Torque Sensor
8.5.2 Temperature Sensor
8.5.2.1 Thermocouple
8.5.2.2 Resistance Temperature Detector
8.5.2.3 Thermistor
8.5.2.4 Monolithic Integrated Circuit Temperature Sensor
8.5.2.5 Infrared Thermometer
8.5.3 Vibration Sensor
8.5.4 Current Sensor
8.5.5 Pressure Sensor
8.5.6 Magnetic Field Sensor
8.6 Improving Motor Sensor Performance
8.6.1 Mitigation of Electrical Noise
8.6.2 Suppression of Temperature Rise
8.6.3 Utilization of Dual- Feedback Solution for Improving Motion Control Accuracy and Reliability
8.7 Development of Innovative Sensor
8.7.1 Sensor Miniaturization—Microsensor and Nanosensor
8.7.2 Advanced Wireless Sensor Technology
8.7.3 Smart Sensors
8.7.4 Color-Changing Dye Sensor for Detecting Motor Condition
8.7.5 Sensor with Newly Developed Material
8.8 Selection of Motor Feedback Devices and Sensors
8.9 Cable Technology
References
Chapter 9 Power Transmission and Gearing Systems
9.1 Characteristics of Gearing Systems
9.1.1 Gearing System Efficiency
9.1.2 Gear Ratio and Torque Ratio
9.1.3 Inertia Matching
9.1.4 Gear Tooth Profile
9.1.5 Backlash
9.1.6 Gearing Stage
9.1.7 Gear Lubrication
9.1.8 Gear Contact Ratio
9.1.9 Temperature Rise and Thermal Effect on Gearing System Performance
9.1.10 Compact Structure
9.1.11 Acoustic Noise
9.1.12 Operation Reliability
9.2 Types of Modern Gearing Systems
9.2.1 Strain Wave Gearing System
9.2.2 Planetary Gearing System
9.2.3 Cycloidal Gearing System
9.2.4 Rotate Vector Gearing System
9.2.5 Magnetic Gearing System
9.2.6 Continuously Variable Strain Wave Transmission
9.2.7 Pulse Drive
9.2.8 Abacus Drive
9.2.9 Circular Wave Drive
9.2.10 Archimedes Drive
9.2.11 Spiral Cam Gearing System
9.2.12 Clutch-Type Stepless Speed Changer
9.3 Conventional Gearing Systems
9.3.1 Spur Gear
9.3.2 Helical Gear
9.3.3 Bevel Gear
9.3.4 Spiroid Gear
9.3.5 Helicon Gear
9.3.6 Worm Gear
9.3.7 Comparison of Conventional Gearing Systems
9.4 Gearhead and Gearmotor
9.4.1 Gearhead
9.4.2 Gearmotor
9.5 Failure of Gearing System
9.6 Selection of Gearing System
References
Chapter 10 Motor Power Losses
10.1 Power Losses in Windings due to Electric Resistance in Copper Wires
10.2 Eddy-Current and Magnetic Hysteresis Losses
10.2.1 Eddy-Current Loss
10.2.2 Magnetic Hysteresis Loss
10.2.3 Calculations of Eddy-Current and Magnetic Hysteresis Losses
10.2.4 Losses in Stator and Rotor Iron Cores
10.2.5 Losses in PMs
10.2.6 Power Losses in Other Core Components
10.3 Mechanical Friction Losses
10.3.1 Bearing Losses
10.3.2 Sealing Losses
10.3.3 Brush Losses
10.4 Windage Losses
10.4.1 Windage Loss due to Rotating Rotor
10.4.1.1 Taylor Vortex
10.4.1.2 Friction Factor
10.4.1.3 Windage Loss Due to Rotating Rotor
10.4.2 Windage Loss due to Entrance Effect of Axial Airgap Flow
10.4.3 Windage Loss due to Stator Surface Roughness
10.4.4 Energy Loss due to Fluid Viscosity
10.4.5 Fan Losses
10.4.6 Ventilating Path Losses
10.4.7 Methods for Reducing Windage Losses
10.5 Stray Load Losses
10.6 Influence of Power Rating on Motor Power Losses
References
Chapter 11 Motor Cooling
11.1 Introduction
11.1.1 Passive and Active Cooling Techniques
11.1.2 Heat Transfer Enhancement Techniques
11.2 Conductive Heat Transfer Techniques
11.2.1 Conductive Heat Flux and Energy Equations
11.2.2 Encapsulation and Impregnation of Electric Motor
11.2.3 Enhanced Heat Transfer Using High-Thermal-Conductivity Material
11.2.4 Using Self-Adhesive Magnet Wire for Fabricating Stator Winding
11.3 Natural Convection Cooling with Fins
11.3.1 Cooling Fin
11.3.2 Fin Optimization
11.3.3 Heatsinks Manufactured with Additive Manufacturing Process
11.3.4 Applications of Various Fins in Motor Cooling
11.3.5 Pin Fin Heatsink
11.3.6 Thermal Interface Materials
11.4 Forced Air Cooling Techniques
11.4.1 Thermophysical Properties of Air
11.4.2 Direct Forced Air Cooling Techniques
11.4.2.1 Forced Air Cooling at End-Winding Regions
11.4.2.2 Forced Air Flowing through Internal Cooling Channels across the Motor
11.4.2.3 Forced Air Flowing Over Motor Outer Surfaces
11.4.2.4 Forced Air Flowing through Both Motor Outer and Inner Surfaces
11.4.2.5 Air Jet Impingement Cooling
11.4.2.6 Cooling with Hydrogen Gas
11.4.3 Indirect Forced Air Cooling Techniques
11.4.3.1 Indirect Forced Air Cooling with Heat Exchangers
11.4.3.2 Indirect Forced Air Cooling via Indirect Evaporative Air Cooler
11.4.4 Fan and Blower
11.4.4.1 Fan Types
11.4.4.2 Forward-Curved, Backward-Curved, and Straight Blades of Centrifugal Fans
11.4.4.3 Fan Performance Curve and Operation Point
11.4.4.4 Fan Selection
11.5 Liquid Cooling Techniques
11.5.1 Thermophysical Properties of Coolants
11.5.2 Direct Liquid Cooling Techniques
11.5.2.1 Direct Liquid Cooling of Bundled Magnet Wires
11.5.2.2 Spray Cooling
11.5.2.3 Direct Liquid Cooling through Hollow Winding Coils/Conductors
11.5.2.4 Liquid Jet Impingement Cooling
11.5.3 Liquid Immersion Cooling
11.5.4 Indirect Liquid Cooling Techniques
11.5.4.1 Indirect Liquid Cooling via Cold Plates Attached to Motor Walls
11.5.4.2 Indirect Liquid Cooling via Helical Copper Pipes Casted in Motor Housing
11.5.4.3 Indirect Liquid Cooling with Cooling Channels on Casted Motor Housing
11.5.4.4 Indirect Liquid Cooling via Copper Pipe in Spacer
11.5.4.5 Indirect Liquid Cooling through Stator Winding Slots
11.5.4.6 Indirect Liquid Cooling through Microscale Channels
11.5.4.7 Indirect Liquid Cooling via Heat Transfer Enhancement Device
11.6 Phase-Change Cooling Techniques
11.6.1 Cooling with Heat Pipes
11.6.2 Cooling with Vapor Chambers
11.6.3 Evaporative Cooling
11.6.4 Mist Cooling
11.7 Radiative Heat Transfer
11.8 Other Advanced State-of-the-Art Cooling Methods
11.8.1 Micro Channel Cooling Systems
11.8.2 Metal Foams
11.8.3 Heat Transfer Enhancement with Nanotechnology
11.8.3.1 Nanofluid
11.8.3.2 Carbon Nanotube
11.8.3.3 NanoSpreader™ Vapor Cooler
11.8.3.4 CarbAl™ Heat Transfer Material
11.8.3.5 Ionic Wind Generator
References
Chapter 12 Motor Vibration and Acoustic Noise
12.1 Vibration and Noise of Electric Motor
12.2 Fundamentals of Vibration
12.2.1 Simple Harmonic Oscillating System
12.2.2 Damped Harmonic Oscillating System
12.2.3 Forced Vibration with Damping
12.2.4 Forced Vibration Due to Mass Unbalance
12.2.5 Vibration Induced by Support Excitation
12.2.6 Directional Vibration
12.3 Electromagnetic Vibrations
12.3.1 Unbalanced Forces/Torques Caused by Electric Supply
12.3.2 Broken Rotor Bar and Cracked End Ring
12.3.3 Unbalanced Magnetic Pull Due to Asymmetric Airgap
12.3.3.1 Electromagnetic Force at Airgap
12.3.3.2 Asymmetric Airgap Due to Nonconcentric Rotor and Stator
12.3.3.3 Asymmetric Airgap Due to Elliptic Stator
12.3.3.4 Asymmetric Airgap Due to Elliptic Rotor
12.3.3.5 Asymmetric Airgap Due to Rotor Misalignment
12.3.3.6 Asymmetric Airgap Resulting from Shaft Deflection
12.3.4 Nonuniform Airgap Due to Stator Slots
12.3.5 Mutual Action Forces between Currents of Stator and Rotor
12.3.6 Vibration Due to Unbalanced Voltage Operation
12.4 Mechanical Vibrations
12.4.1 Misaligned Shaft and Distorted Coupling
12.4.2 Defective Bearing
12.4.3 Self-Excited Vibration
12.4.4 Torsional Vibration
12.5 Vibration Measurements
12.6 Vibration Control
12.6.1 Damping Materials
12.6.2 Vibration Isolation
12.6.3 Magnetorheological Damper and Machine Mount
12.6.4 Tuned Mass Damper
12.6.5 Double Mounting Isolation System
12.6.6 Viscoelastic Bearing Support
12.6.7 Self-Locking Fastener
12.6.7.1 Hard Lock Nut
12.6.7.2 Super Lock Nut and Super Stud Bolt
12.6.7.3 Self-Locking Nut
12.6.7.4 Jam Nut
12.6.7.5 Serrated Face Nut and Bolt
12.6.7.6 Nord-Lock Washer
12.6.8 Active Vibration Isolation and Damping
12.6.9 Measurements of Motor Vibration
12.7 Fundamentals of Acoustic Noise
12.7.1 Tonal Noise and Broadband Noise
12.7.2 Sound Pressure Level and Sound Power Level
12.7.3 Octave Frequency Bands
12.7.4 Three Sound Weighting Scales
12.7.5 Averaged Sound Pressure Level
12.7.6 Type of Noise
12.7.6.1 Structure-Borne Noise
12.7.6.2 Airborne Noise
12.7.6.3 Type of Aerodynamic Noise
12.8 Noise Classification and Measurement in Rotating Electric Machine
12.8.1 Noise Type in Rotating Electric Machine
12.8.1.1 Mechanical Noise
12.8.1.2 Electromagnetic Noise
12.8.1.3 Aerodynamic Noise
12.8.2 Acoustic Anechoic Chamber
12.8.3 Measurement of Motor Noise
12.8.4 Acoustic Noise Field Measurement
12.9 Motor Noise Abatement Techniques
12.9.1 Active Noise Reduction Techniques
12.9.2 Passive Noise Reduction Techniques
12.9.2.1 Blocking Noise Propagation Paths and Isolating Noise Sources
12.9.2.2 Using Noise-Absorbing Material
12.9.2.3 Motor Suspension Mounting
12.9.2.4 Noise-Attenuating Structure
12.9.2.5 Smoothing Ventilation Path
12.9.2.6 Selecting Low Noise Bearing
12.9.3 Innovative Noise Abatement Methods
References
Chapter 13 Motor Testing
13.1 Motor Testing Standards
13.2 Testing Equipment and Measuring Instruments
13.2.1 Dynamometer
13.2.2 Thermocouples and Other Temperature Measuring Devices
13.2.3 Control System
13.2.4 Data Acquisition System
13.2.5 Torque Transducer
13.2.6 Power Quality Analyzer
13.2.7 Power Supply
13.2.8 Motor Test Platform
13.3 Testing Load Level
13.4 Testing Methods
13.4.1 Mechanical Differential Testing Method
13.4.2 Back-to-Back Testing Method
13.4.3 Indirect Loading Testing Method
13.4.4 Forward Short-Circuit Testing Method
13.4.5 Variable Inertia Testing Method
13.5 Off-Line Motor Testing
13.5.1 Winding Electrical Resistance Testing
13.5.2 Megohm Testing
13.5.3 Polarization Index Testing
13.5.4 High-Potential Testing
13.5.5 Surge Testing
13.5.6 Step-Voltage Testing
13.5.7 Determination of Rotor’s Moment of Inertia
13.6 Online Motor Testing
13.6.1 Locked Rotor Testing
13.6.2 Motor Heat Run Testing
13.6.3 Motor Efficiency Testing
13.6.4 Impulse Testing
13.6.5 Cogging Torque Testing
13.6.6 Torque Ripple Measurement
References
Chapter 14 Modeling, Simulation, and Analysis of Electric Motors
14.1 Computational Fluid Dynamics and Numerical Heat Transfer
14.1.1 Strategies in Modeling and Performing CFD Analysis
14.1.2 Rotating Flow Modeling
14.1.3 Porous Media Modeling
14.1.4 Numerical Simulation of Motor Cooling
14.1.4.1 Mathematical Formulations
14.1.4.2 Numerical Method
14.1.4.3 Case Study—3D Thermal Analysis of Large Size Motor
14.1.4.4 Simulation of Two-Phase Flow and Heat Transfer
14.2 Thermal Simulation with Lumped-Circuit Modeling
14.3 Thermal Analysis Using the Finite Element Method
14.4 Rotordynamic Analysis
14.4.1 Problem Description
14.4.2 Bearing Support’s Stiffness and Damping
14.4.3 Rotordynamic Modeling
14.4.4 Results of Rotordynamic Analysis
14.5 Static and Dynamic Stress/Strain Analysis
14.5.1 Static Analysis
14.5.2 Dynamic Analysis
14.5.2.1 Centrifugal Force-Induced Stress on PMs
14.5.2.2 Structural Analysis Using the Finite Element Method
14.5.3 Shock Load
14.6 Fatigue Analysis
14.7 Torsional Resonance Analysis
14.8 Motor Noise Prediction
14.9 Buckling Analysis
14.10 Thermally Induced Stress Analysis
14.11 Thermal Expansion and Contraction Analysis
References
Chapter 15 Innovative and Advanced Motor Design
15.1 High-Temperature Superconducting Motor
15.2 Radial-Flux Multirotor or Multistator Motor
15.2.1 Radial-Flux Multirotor Motor
15.2.2 Radial-Flux Multistator Motor
15.2.3 Radial-Flux Brushless Dual-Rotor Machine
15.2.4 Radial-Flux Dual-Stator PM Machine
15.2.5 High-Torque PM Motor with 3D Circumferential Flux Design
15.2.6 Radial-Flux Dual-Rotor, Dual-Stator Motor
15.2.7 Radial-Flux Integrated Magnetic-Geared In-Wheel Motor
15.3 Axial-Flux Multirotor or Multistator Motor
15.3.1 Single-Sided and Double-Sided Axial-Flux Motors
15.3.2 Multistage Axial-Flux Motor
15.3.3 Yokeless and Segmented Armature Motors
15.3.4 Energy Efc fi ient Axial-Flux Yokeless Motor with Modular Stator
15.3.5 Axial-Flux Motor with PCB Stator
15.4 Hybrid Motor
15.4.1 Hybrid Excitation Synchronous Machine
15.4.2 Hybrid Hysteresis PM Synchronous Motor
15.4.3 Hybrid Motor Integrating RF Motor and AF Motor
15.4.4 Hybrid-Field Flux-Controllable PM Motor
15.4.5 Hybrid Linear Motor
15.5 Conical Rotor Motor
15.6 Transverse Flux Motor
15.7 Recong fi urable PM Motor
15.8 Variable Reluctance Motor
15.9 PM Memory Motor
15.9.1 Variable Flux PM Memory Motor
15.9.2 Pole-Changing PM Memory Motor
15.9.3 Doubly Salient Memory Motor
15.10 Adjustable and Controllable Axial Rotor/Stator Alignment Motor
15.11 Piezoelectric Motor
15.12 Advanced Electric Machines for Renewable Energy
15.13 Micromotor, Nanomotor, and Molecular Motor
15.13.1 Micromotor
15.13.2 Nanomotor
15.13.3 Molecular Motor
References
Appendix A: Advanced Interconnection Technology for Motors
Index