Preface
Electric motors have been an important element of our industrial and
commercial economy for over a century. Hundreds of books and
thousands of scholarly works have been written about electric motors
over the years. So it is fair to ask, “Why are we writing yet another book
about motors?” The answer to this lies in an observation that one might
make about the existing literature.
Virtually all books on electric machinery can be categorized as being
introductory (that is textbooks), theoretical (principally having to do
with design) or practical books about application. The introductory
books typically do not concern the reader with any hard numbers. They
simply try to promote a basic understanding of how motors and
generators operate. Books on motor design are full of formulae useful
to a machine designer who has a motor specification to fill, but say
little if anything about application. Finally, in our experience,
applications-oriented books tend to view the machine as a ‘black box’,
with little disclosure about what is inside and where the real limits of
the machine might lie.
This book is for the applications engineer, as opposed to the machine
designer. It embodies the premise that effective application of electric
motors requires an understanding of the internal mechanisms and
physical principles on which the motor operates. For this reason it
incorporates quite a lot of “theory” of operation. However, it also
incorporates much practical knowledge, such as recommendations for
machine type in certain applications and discussion of standards. It
also incorporates a chapter on motor drives, as much application of
electric motors will also incorporate power electronic controls, and a
chapter on motor noise, an increasingly important consideration in
many products.
Much of the theoretical material in this book had as its origin a set of
notes for a Summer Professional Institute subject at the Massachusetts
Institute of Technology called “Design of Electric Motors, Generators
and Drive Systems”.
Despite the long existence of electric motors and their importance in
the modern world, more applications are found continually for them. As
motors are more closely integrated into products and systems, and as
drive electronics and motors become more closely integrated, a firm
understanding of how the motors work, including their internal limits,
production of noise and heat, and physical and electrical parameters,
will be increasingly important for the applications engineer.
