DC Motors, Speed Controls, Servo Systems

DC Motors, Speed Controls, Servo Systems

An Engineering Handbook

3rd Edition - January 1, 1972

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  • Author: Unknown Author
  • eBook ISBN: 9781483148373

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DC Motors - Speed Controls - Servo Systems: An Engineering Handbook is a seven-chapter text that covers the basic concept, principles, and applications of DC and speed motors and servo systems. After providing the terminology, symbols, and systems of units, this book goes on dealing with the basic theory, motor comparison, and basic speed control methods of motors. The subsequent chapters describe the phase-locked servo systems and their optimization and applications. These topics are followed by a discussion of the developments made by Electro-Craft in the field of DC Brushless Motors. The final chapter provides revised data sheets on Electro-Craft products and describes the models in the motomatic range of speed controls, servomotor controls, and digital positioning systems. This handbook is of great value to professional engineers and engineering students.

Table of Contents

  • Foreword

    Chapter 1. Terminology, Symbols, Systems of Units

    1.1. Terminology

    1.2. Symbols

    1.3. Systems of Units

    Chapter 2. DC Motors and Generators

    2.1. Basic Theory

    Historical Background

    Concept of Torque and Power

    Law of Electromagnetic Induction

    Magnetic Circuit Principles

    Magnetomotive Force

    Magnetic Flux

    Magnetic Flux Density


    Magnetic Field Intensity

    Working Equations for Voltage and Torque




    2.2. Motor Comparison

    General Description

    Wound-Field Motors

    Permanent Magnet Motors

    2.3. Motor Equations and Transfer Function

    2.3.1. Electrical Equations

    2.3.2. Dynamic Equations

    2.3.3. Motor Transfer Function

    2.3.4. Torsional Resonance

    2.3.5. Speed-Torque Curve

    2.4. Power Dissipation in DC Motors

    2.4.1. Origins of Power Dissipation

    2.4.2. Power Dissipation

    2.4.3. Dissipation at Constant Velocity

    2.4.4. Dissipation During Incremental Motion

    2.5. Thermal Characterisitcs of DC Motors

    2.5.1. Continuous Operation

    2.5.2. Intermittent Operation

    2.5.3. Thermal Model

    2.5.4. Thermal Equations

    2.5.5. Thermal Analysis

    2.6. Motor Characteristics and Temperature

    Armature Resistance

    Torque Constant and Voltage Constant

    Derating Motor Torque

    2.7. Other Characteristics



    Noise and Dynamic Balancing

    Noise Caused by Side Loading

    Bearing Noise

    Brush Noise

    Environmental Considerations

    Brush Wear

    Motor Life

    Demagnetization of PM Motors

    2.8. Moving Coil Motors (MCM)

    Moving Coil Motors

    Moving Coil Motors and Motor Ratings

    Thermal Properties

    Resonant Phenomena in Moving Coil Motors

    Demagnetizing Current

    2.9. Specialty Motors - Permanent Magnet Motors with Variable KT

    2.9.1. Introduction

    2.9.2. The Wound-Field Motor

    2.9.3. New Motor Types

    2.10.Motor Testing

    End Play

    Radial Play

    Shaft Runout

    Moment of Inertia



    Friction Torque and Starting Current

    No-Load Current and Rotational Losses, No-Load Voltage, No-Load Speed

    Demagnetization Current

    Torque Constant

    Voltage Constant

    Electrical Time Constant

    Mechanical Time Constant

    Torque Ripple

    Speed Regulation Constant


    Frequency Response

    Thermal Resistance

    Thermal Time Constant

    Air Flow Impedance

    Incoming Inspection of Motors

    Motor Troubleshooting Chart

    2.11. DC Generators



    Types of DC Generators

    Mounting Features

    Temperature Effects

    Ultrastable Generators

    Stable Generators

    Compensated Generators

    Uncompensated Generators

    Linearity and Load Effects

    2.12. Generator Testing

    Output Impedance

    Voltage Gradient

    Voltage Polarity

    Generator Ripple

    Iron-Core Generator Ripple

    Moving Coil Tachometer Ripple

    Temperature Coefficient

    Dielectric Test



    Incoming Inspection

    Generator Troubleshooting Chart

    Chapter 3. Unidirectional Speed Controls

    3.1. Basic Control Methods

    Speed Controllers-An Introduction

    Open Loop Controls-The Traditional Approach

    Closed-Loop Controls

    Speed Controls VS. Servo Systems

    3.2. Velocity Control Single Quadrant Controller

    Voltage and Current of A Single Quadrant Controller

    System Operation

    Dynamic Braking

    3.3. Amplifiers

    The Linear Amplifier

    Torque Limiting

    Dynamic Braking Devices

    Reversible Speed Controls

    Controlled Acceleration-Deceleration System

    Switching Amplifiers

    Pulse-Width Modulated Amplifiers

    SCR Controls

    Chapter 4. Speed Controls and Servo Systems

    4.1. Servo Theory

    Laplace Transformation

    Inverse Laplace Transformation

    Transfer Functions

    Block Diagrams

    Transfer Function of a DC Motor

    Transfer Function of an Amplifier


    Root Locus Method

    4.2 Servo Components

    4.2.1. DC Motor

    4.2.2. Amplifier

    4.2.3. Amplifier-Motor System

    4.2.4. Tachometer

    4.2.5. Potentiometer

    4.2.6. Linear Variation Differential Transformer (LVDT)

    4.2.7. Encoders

    4.3. Servo Systems

    4.3.1. Introduction

    4.3.2. Velocity Control Systems

    4.3.3. Position Control Systems

    4.3.4. Torque Control Systems

    4.3.5. Hybrid Control Systems

    4.4. System Characteristics

    4.4.1. Response of the System to a Step Command

    4.4.2. System Bandwidth

    4.4.3. Effect of Torsional Resonance

    4.5. Servo Amplifiers

    4.5.1. Linear Amplifiers

    4.5.2. SCR Amplifiers

    4.5.3. Switching Amplifiers

    4.6. Phase-Locked Servo Systems

    4.6.1. Introduction

    4.6.2. System Components

    4.6.3. System Design and Stability

    4.6.4. Special Characteristics

    4.7. How to Make Systems Work

    4.8. Optimization

    4.8.1. Introduction

    4.8.2. Velocity Profile Optimization

    4.8.3. Coupling Ratio Optimization

    4.8.4. Capstan Optimization

    4.8.5. Optimum Motor Selection for Incremental Application

    4.9. Permanent Magnet Motors for Servo Applications

    4.10. Systems and Controls Troubleshooting

    Theoretical Failure-Symptom Chart

    Chapter 5. Applications

    5.1. Introduction

    5.2. System Classification and Specification

    5.2.1. Classification

    5.2.2. Specification

    5.3. Motor Selection Criteria

    5.3.1. Introduction

    5.3.2. When to Specify

    5.3.3. What to Consider

    5.3.4. Selection Analysis

    5.4. Application of Motomatic Systems

    5.4.1. Speed Range

    5.4.2. Output Torque and Ambient Temperature

    5.4.3. Speed Regulation and Stability

    5.4.4. Motomatic Speed Control Features

    5.4.5. Series E-550 Motomatic Controls

    5.4.6. Series E-650 Motomatic Controls

    5.5. Application Examples

    Office Copying Machine

    Hydraulic Motor Drives

    Automatic Retrieval System

    Speed-Torque Analyzer

    Energy Chopper

    Laboratory Stirrer

    Filament Winding Machine

    Rewinder Speed Control

    Multi-Motor Control for Industrial Knitting Machines

    Semiconductor Manufacturing Photoresist Spinner

    Blood Oxygenator

    Infusion Pump

    Crystal Pulling Machine

    Conveyor Feed Rate Control

    Reflow Soldering

    Drive for Disc Memory Testing

    Variable Speed Tape Recorder

    Motor Testing

    Tachometer Ripple Voltage Testing

    Torque Limiter

    Paper Web Wind-Up Control

    Welding Machines

    Bidirectional Position Control

    Muscle Exerciser - Medical Rehabilitation Device

    Punch Press Feed Control

    Connector Test Station

    Blueprint Machine Drive

    Film Scanning Device

    Drive for Chart Recorder

    Paper Cutting Control

    Blood Cell Separator

    Adjustable Lathe Feed Rate Control

    Contour Lathe

    Three-Axis Milling Machine Control

    Linear Drive System

    Phototypesetter Application

    Diamond Sorting System

    Printed Circuit Solder Fusing Machine

    Component Marking System

    5.6. Incremental Motion Applications

    5.6.1. Introduction

    5.6.2. Selecting the Proper Servomotor for an Incremental Motion System

    5.6.3. Tag Printer Feed Drive

    5.6.4. Conveyor Drive System

    5.6.5. Computer Tape Transport Reel Motor

    5.7. Application of P6000 Series Servo Motor Systems

    5.7.1. General Description of the P6000 Range of Servo Motor Controls

    5.7.2. Standard Options

    5.7.3. Standard Drive Packages

    5.7.4. Amplifier Installation

    5.7.5. Control Adjustments

    5.7.6. Customer Connections

    5.7.7. Summing Amplifier Compensation

    5.7.8. Ramp Generator Adjustment

    5.7.9. In Case of Difficulty

    5.7.10. Troubleshooting Guide

    Chapter 6. Brushless DC Motors

    6.1. Introduction

    6.2. Definition of a Brushless DC Motor System

    6.3. Practical Solutions to Brushless Commutation

    6.4. Torque Generation by Various Controller Configurations

    6.4.1. The Sinusoidal Control Scheme

    6.4.2. Trapezoidal Torque Function

    6.5. Commutation Sensor Systems

    6.6. Power Control Methods

    6.7. Motor Constants

    6.8. Brushless DC Tachometers

    6.9. Examples of Brushless Motors

    6.10. Summary

    6.11. Step Motors Versus Brushless DC Motors in Digital Position Systems

    6.11.1. Introduction

    6.11.2. Step Motor Performance Limitations

    6.11.3. Brushless DC Motor Incremental Motion Control

    6.11.4. Conclusion

    Chapter 7. Electro-Craft Corporation Products

    7.1. DC Servomotors






    7.2. Servomotor Generators








    7.3. Moving Coil Motors








    7.4. Tachometers-Generators



    7.5. Special Hybrid Motors

    H-5200 Series

    7.6. Servomotor Controls and Systems

    7.6.1. Motor Speed Controls

    7.6.2. P6000 Pulse Width Modulated DC Servomotor Controllers

    7.6.3. SD6 Series Servo System Packages

    7.6.4. L5000 Linear Servomotor Controls

    7.6.5. Options for Use With P6000 and L5000 Controls

    7.7. Brushless DC Motors

    BLM 340

    BLM 341

    BLM 342

    7.8. Servo Systems for Engineering Education

    Motomatic Control System Laboratory (MCSL)

    Motomatic Experimenter


    A.1. SI System of Units Metric System

    Definition of Basic SI Units




    Electric Current

    Temperature Difference

    Review of Main SI Units and Secondary Units

    Mechanical Units

    Electrical and Magnetic Units

    A.2. Units' Conversion Factors and Tables

    Conversion Factors

    Torque-Power-Speed Nomograph

    Moment of Inertia Conversion Factors

    Torque Conversion Factors


    Relationship of the Speed, Torque and Output Power of a Motor

    Inches to Millimeters Conversion

    Celsius to Fahrenheit Degrees



Product details

  • No. of pages: 510
  • Language: English
  • Copyright: © Pergamon 1972
  • Published: January 1, 1972
  • Imprint: Pergamon
  • eBook ISBN: 9781483148373

About the Author

Unknown Author

Dr. Sam Stuart is a physiotherapist and a research Fellow within the Balance Disorders Laboratory, OHSU. His work focuses on vision, cognition and gait in neurological disorders, examining how technology-based interventions influence these factors. He has published extensively in world leading clinical and engineering journals focusing on a broad range of activities such as real-world data analytics, algorithm development for wearable technology and provided expert opinion on technology for concussion assessment for robust player management. He is currently a guest editor for special issues (sports medicine and transcranial direct current stimulation for motor rehabilitation) within Physiological Measurement and Journal of NeuroEngineering and Rehabilitation, respectively.

Affiliations and Expertise

Senior Research Fellow, Department of Sport, Exercise and Rehabilitation, Northumbria University, UK Honorary Physiotherapist, Northumbria Healthcare NHS Foundation Trust, North Shields, UK

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