Prof. Ion Boldea                                                   May 2002

IEEE Fellow



                                                                                    A review of the book:


            “Permanent Magnet Motor Technology-design and applications”/second edition


by J.F. Gieras & M. Wing,


published by Marcel Dekker Inc, New York. Basel, 2002,


Permanent Magnets, which may be considered as equivalents of “superconductor coils at room temperature” at affordable prices, have brought to electric motors the advantages of lower losses and higher torque densities in the whole speed range for a myriad of applications from hard disk and DVD drives to Electric and Hybrid vehicles. PM motors markets are already rather mature but very dynamic though.


This second edition, revised and expanded, of J.F. Gieras and M.Wing’s book with same title and publisher printed first in 1996 , structured in 12 chapters with 2 Appendixes, along 583 pp., is dedicated to this timely subject.


It is both an up-to-date monograph and a textbook for senior-undergraduate or graduate courses but it is remarkably practical and thus useful as a handbook for PM motor design and industrial engineers.


It covers both basic principles and performance but also advanced models and configurations with their design. The numerical examples abound to give

a strong feeling of magnitudes.


The authors’ remarkable work and experience in the field is reflected in the contents, but the references are fully representative and their contribution is given notable priority.


The book starts with an Introduction where the main brush and brushless PM motors are presented and their superior performance is explained. Fundamentals of machine mechanics are also given.


Permanent Magnet Materials and Circuits are presented in considerable detail in Chapter 2.


Finite Element Analysis basics and its application to calculate the field distribution, torque and inductances of PM motors are given in Chapter 3 in a  synthetic manner.


Chapter 3 contains a thorough analytical theory of PM Synchronous (brushless ac) Motors with frequent FEM validation examples.

The dc Commutator PM Motors are treated in chapter 4 in terms of construction, fundamental equations, sizing procedure, speed control, magnetic circuit and applications


Fundamental relationships, phasor diagram, reactances, rotor configurations, dynamic model, noise and vibration  and applications are the main subjects of chapter 5.


Chapter 6 deals with d.c.  Brushless(trapezoidal current) Motors from fundamental equations, commutaion, emf  and torque to rotor position sensing,

sensorless operation, smart (integral) motors and applications.


Axial flux (air-gap) PM Motors with their various configurations, theory, performance and applications are presented Chapter 7


High Power Density Brushless Motors  are given a rather detailed treatment in Chapter 8, stressing the necessity of reducing the armature effect to maintain a reasonable power factor and thus a reasonable converter cost. Though cylindrical rotor configurations are treated, the main attention is focused on the “Transverse Flux Machine”  with a convincing design example available. Potential applications are illustrated.


Brushless Motors of special construction-single-phase, micro-motors and high speed PM and slotless motors- are presented in Chapter 9  while  Chapter 10 pertinently treats stepping PM motors.


Design optimization is dedicated a full Chapter (Chapter 11) where various methods are introduced and ranked and two numerical examples - one for the dc brush and the other for the PM synchronous motor - are given.


Aspects of maintenance are treated in considerable detail in Chapter 12.


Formulae for leakage inductances and losses of ac motors are given in the two Appendixes.


A bibliography with 266 titles and an index close the book at page 590.


In summary we can say that this new edition is up-to date, it covers a large spectrum of theoretical and practical issues in considerable depth, and thus it should be on the desk of all who intend to study, design, fabricate or use PM motors in practically all industries.