The book Design of Brushless Permanent-Magnet Machines by J.R. Hendershot and T.J.E. Miller is fully revised and expanded from the first edition that the authors published back in 1994.

“Engineering is a practical art with just enough theory,” the authors say. In what a lot of designers consider the dark art that is electric machine design, the authors manage to shed much light.

The authors bring a wealth of not only theoretical knowledge but practical design experience to the new edition which serves to ground the book in the day-to-day world of the practicing design engineer.

Who will benefit from the book? First and foremost, those engineers who are designing the motors and controllers themselves. But the book also benefits the systems integrators and designers who are putting together motion control systems because it is a great in-depth guide for anyone interested in the inner workings of brushless permanent-magnet (PM) machines. The emphasis is on motors, but there is a chapter devoted to generators as well.

One of the most innovative features of the book is the chapter devoted to k_T and k_E, the so-called figures of merit. These two constants point out the fundamental relationship in any electric machine between the current and torque and between speed and EMF. The authors look squarely at the fact that different manufacturers use different conventions and definitions for these parameters and attempt to bring some clarity to the situation.

There is also a useful chapter on losses and cooling and a chapter that treats both square wave and sine wave drives. The back sections of the book include an extensive list of symbols and abbreviations, as well as an appendix with FAQ about machine design.

With the Internet and the Web as one of, if not the primary, source of information for busy designers these days, it can sometimes feel that a lot of information is scattered all around the Web and it takes considerable effort and Googling to find what you’re looking for. Here, everything you need to know about PM machine design is in one physical book. The extensive bibliography contains over 300 references, many of which, as the authors point out, are simply not available on the Internet, residing in books and archival journals published before 1980.

In my undergraduate days and during my first co-op work experience, I found a book at my employer that served me well for getting to the heart of a technical matter like no classroom textbook could. The Art of Electronics by Horowitz and Hill was an indispensable bible of electronic circuit knowledge. This book has something of that spirit in that it is comprehensive and practical, although it does unquestionably contain more mathematics, as motor design, by its very nature, demands it, and takes care to mention and discuss the practical considerations of machine design.

All in all, the book is quite an achievement and a welcome addition to the designer’s reference shelf.

– Miles Budimir