1st Edition

Permanent Magnet Synchronous and Brushless DC Motor Drives

By Ramu Krishnan Copyright 2010
    612 Pages 309 B/W Illustrations
    by CRC Press

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    Despite two decades of massive strides in research and development on control strategies and their subsequent implementation, most books on permanent magnet motor drives still focus primarily on motor design, providing only elementary coverage of control and converters.

    Addressing that gap with information that has largely been disseminated only in journals and at conferences, Permanent Magnet Synchronous and Brushless DC Motor Drives is a long-awaited comprehensive overview of power electronic converters for permanent magnet synchronous machines and control strategies for variable-speed operation. It introduces machines, power devices, inverters, and control, and addresses modeling, implementation, control strategies, and flux weakening operations, as well as parameter sensitivity, and rotor position sensorless control. Suitable for both industrial and academic audiences, this book also covers the simulation, low cost inverter topologies, and commutation torque ripple of PM brushless DC motor drives. Simulation of the motor drives system is illustrated with MATLAB® codes in the text.

    This book is divided into three parts—fundamentals of PM synchronous and brushless dc machines, power devices, inverters; PM synchronous motor drives, and brushless dc motor drives. With regard to the power electronics associated with these drive systems, the author:

    • Explores use of the standard three-phase bridge inverter for driving the machine, power factor correction, and inverter control
    • Introduces space vector modulation step by step and contrasts with PWM
    • Details dead time effects in the inverter, and its compensation
    • Discusses new power converter topologies being considered for low-cost drive systems in PM brushless DC motor drives

    This reference is dedicated exclusively to PM ac machines, with a timely emphasis on control and standard, and low-cost converter topologies. Widely used for teaching at the doctoral level and for industrial audiences both in the U.S. and abroad, it will be a welcome addition to any engineer’s library.

    PART I: Introduction to Permanent Magnets and Machines and Converters and Control

    Chapter 1 Permanent Magnets and Machines

    Permanent Magnets

    Arrangement of PMs

    Magnetization of PMs

    PM ac Machines

    Fundamentals of Synchronous Machines

    Fundamental Synchronous Machine Relationships

    Core Losses

    Resistive Losses

    Initial Machine Design

    Cogging Torque

    Basic Types of PMSMs Based on Flux Paths

    Vibration and Noise


    Chapter 2 Introduction to Inverters and Their Control

    Power Device

    DC Input Source

    DC to ac Power Conversion

    Real Power

    Reactive Power

    Need for Inverter Control

    Pulse Width Modulation

    Hysteresis Current Control

    Space Vector Modulation

    Inverter Switching Delay

    Input Power Factor Correction Circuit

    Four-Quadrant Operation

    Converter Requirements


    PART II: Permanent Magnet Synchronous Machines and Their Control

    Chapter 3 Dynamic Modeling of Permanent Magnet Synchronous Machines

    Real-Time Model of a Two-Phase PMSM

    Transformation to Rotor Reference Frames

    Three-Phase to Two-Phase Transformation

    Zero Sequence Inductance Derivation

    Power Equivalence

    Electromagnetic Torque

    Steady-State Torque Characteristics

    Models in Flux Linkages

    Equivalent Circuits

    Per Unit Model

    Dynamic Simulation

    Small-Signal Equations of the PMSM

    Evaluation of Control Characteristics of the PMSM

    Computation of Time Responses

    Space Phasor Model

    Chapter 4 Control Strategies for a Permanent Magnet Synchronous Machine

    Vector Control

    Derivation of Vector Control

    Drive System Schematic

    Control Strategies

    Chapter 5 Flux-Weakening Operation

    Maximum Speed

    Flux-Weakening Algorithm

    Direct Flux Weakening

    Parameter Sensitivity

    Model-Free (Parameter-Insensitive) Flux-Weakening Method

    Six-Step Voltage and Constant Back EMF Control

    Strategies for PMSM

    Direct Steady-State Evaluation

    Flux Weakening in SMPM and IPM Synchronous Machines

    Chapter 6 Design of Current and Speed Controllers

    Current Controller

    Speed Controller

    Chapter 7 Parameter Sensitivity and Compensation


    Parameter Compensation through Air Gap Power Feedback Control

    Parameter Compensation by Reactive Power Feedback Control

    Chapter 8 Rotor Position Estimation and Position Sensorless Control

    Current Model Adaptive Scheme

    Sensing by External Signal Injection

    Current Model-Based Injection Scheme

    Position Estimation Using PWM Carrier Components


    PART III: Permanent Magnet Brushless DC Machines and Their Control

    Chapter 9 PM Brushless DC Machine

    Modeling of PM Brushless DC Motor

    Normalized System Equations

    The PMBDCM Drive Scheme

    Dynamic Simulation

    Chapter 10 Commutation Torque Ripple and Phase Advancing

    Commutation Torque Ripple

    Phase Advancing

    Dynamic Modeling

    Chapter 11 Half-Wave PMBDCM Drives

    Split Supply Converter Topology

    C-Dump Topology

    Variable DC Link Converter Topology

    Variable Voltage Converter Topology with Buck-Boost Front-End

    Chapter 12 Design of Current and Speed Controllers

    Transfer Function of Machine and Load

    Inverter Transfer Function

    Transfer Functions of Current and Speed Controllers

    Current Feedback

    Speed Feedback

    Design of Controllers

    Chapter 13 Sensorless Control of PMBDCM Drive

    Current Sensing

    Position Estimation

    Chapter 14 Special Issues

    Torque Smoothing

    Parameter Sensitivity of the PMBDCM Drive

    Faults and Their Diagnosis

    Vibration and Noise



    R. Krishnan is a professor of electrical and computer engineering at Virginia Tech, Blacksburg, USA, and the director of the Center for Rapid Transit Systems, specializing in linear and rotating motor drives. He is the author of Switched Reluctance Motor Drives (CRC Press), among other books, and his inventions have been prominently featured in radio, TV, and newspapers such as The Wall Street Journal. He has served as a consultant for 18 companies in the United States and has received best paper prize awards from the IEEE Industry Applications Society’s Industrial Drives Committee and the Electric Machines Committee, and Industrial Electronics Society. An IEEE Fellow, Professor Krishnan was awarded the Mittelman Award for outstanding achievement in industrial electronics from that society. He is a founder of two companies involved in variable speed motor drives, and he is a co-founder of a linear motor drives company.