Sunday, 29 January 2012

Electric Motors and Drives: Fundamentals, Types, and Applications

Electric Motors and Drives: Fundamentals, Types, and Applications
by Dennis L. Feucht

ENFirst published in 1990, the aim of this book is to hit somewhere between academic textbooks and "prosaic" books that provide little insight into useful concepts. I would regard the book as technician-level, yet with useful content for engineers who know nothing about motors. The author is a Senior Lecturer in the EE Department at the University of Leeds. He writes in a lucid and readable style, and appears to have the knack of cutting to the key issues, bringing out some of the important aspects of motor design that are often not made explicit in academic textbooks. The eleven chapters have review questions, with numerical answers provided.
After covering basic ideas of torque production in motors using simple algebra, motor drive basics are introduced, with emphasis upon higher-power control, using thyristors for turn-on angle control. This can produce an average voltage in much the same way PWMing does. The most basic BJT and MOSFET power driver circuits are included along with discussion of thermal management. All this is very introductory.
In Chapter 3, dc motors are explained in somewhat more detail, with emphasis upon an intuitive understanding of the various mechanisms (such as armature reaction, the effect of the winding B-field on the force-producing field) without much math to quantify them. Others include four-quadrant and regenerative drive and dynamic braking.
Chapter 4 introduces the idea of motor control, with some feedback. Again, only basic ideas are introduced. Chapters 5 and 6 get into induction motors and simple forms of their control, such as soft starting, plug reversal and injection braking.
From an engineering standpoint, Chapter 7 becomes more interesting: it covers basic transformer theory for the purpose of giving an induction motor equivalent circuit. Induction motor control schemes briefly describe vector or field-oriented control, but without providing much insight into its basic principles. Cycloconverters are also briefly explained.
Succeeding chapters cover stepping motors, PMS, and VR motors. For practical use of motors, the book concludes with a chapter on motor and drive selection. The appendix is a basic tutorial on feedback control theory.
The author perpetuates some obsolete language (such as emf) and emphasizes well-established ideas in motors and their control. He writes with long-term experience. I would regard the book as a light but broad coverage of many motor and drive concepts that have been around for a long time. It falls far short of engineering depth but does offer to a novice a broad overview -- a place to start in learning about motors and drives.

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