Page 4 - Electric Drives and Electromechanical Systems

Preface

Since the completion of the first edition of this book in 2004, the landscape associated with
drive systems has significantly evolved, with the widespread introduction of networking,
including connections to the Internet to realise the Industry 4.0 concept. This revised version
reflects these changes, while maintaining a focus on the underlying electromechanical
system, as the incorrect selection of the motor can never be overcome by the application of
modern control theory, advanced artificial intelligence or data analytics.
Electrical drives act as the electromechanical energy converter in a wide range of
applications, for example machine tools in manufacturing industries, photocopies, electric
automotive applications, prosthetic hands and other medical devices; some are obvious other
not so, until the they fail. It is critically important that the correct drive is matched to the
application with due regard to its requirements. With the recent developments in power
semiconductors and microprocessors with signal processing capabilities, the technology of
the modern drive system has changed dramatically in recent years. However, the selection of
a drive system relies on a systems approach - without which, it is highly probable that either
the mechanical, electrical electronic or computational will not perform to the required
standard or fail if not be fully considered.
A complete drive system consists of many different components; hence this book has
been structured to present a logical discussion, on a wide range of topics relating to selection
of the complete motor-drive system. It does not, however, extend to a detailed consideration
of control and electromagnetic theory; if the reader wishes to pursue this path many excellent
books or academic papers are available, some of which are noted in the bibliography.
The structure of the book is as follows. Chapter 1 gives a brief overview of the problems
that need to be solved, with emphasis on a wide range of electromechanical applications,
including machine tools, robotics and related high-performance applications. Chapters 2 and
3 concentrate on the problem of motor-drive selection and give an insight into the decisions
required during this procedure. It is hoped that this will lift the veil on what is thought
by many to be a black art, or on what more commonly falls into the gap between the
responsibilities of electrical, electronic, and mechanical engineers. Chapter 3 concludes with
suitable algorithms to size a wide range of applications. Chapter 4 considers the types,
selection and installation of velocity and position transducers, the correct selection of which
will have a significant impact on the overall performance of the system. To illustrate the
various points in the chapters, use has been made of a range of numerical examples, and
hopefully these will show how the theory can be applied.
While the initial chapters concentrate on the mechanical aspects of a drive application,
the second part of the book concentrates on the main classes of drives, which are available,
and are used, to drive the applications discussed in Chapter 1. The technologies considered
include: the brushed d.c. motor (Chapter 5), brushless motors (Chapter 6), vector-controlled
induction motors (Chapter 7), and the stepper motor (Chapter 8). In addition, several types of
actuators fall outside this rather arbitrary classification system and are considered in Chapter
9. It should be recognised that some of the larger drive systems have been omitted, due to the
application domain being restricted to small or medium sized applications. Within each of
these chapters there is an overview of the relevant theory, and an examination of the specific
drive and control requirements.

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