BOOK REVIEWS
Switched mode power supplies: design and construction
H. W. Whittington, B. W. Flynn and D. E. Macpherson
Research Studies Press Ltd. (2nd Edn.), 1997, 236 pp., £50, ISBN 0 86380 203 6
T
he vast increase in the use of electronics in a wide range of domestic
and industrial equipment, not least of
which the all-pervading PC, has brought
increased pressure on the manufacturers
of switched mode power supplies, with
growing demands for higher performance, reduced size and lower cost. This
second edition reflects some of the
changes that have been made in
response to these demands.
Coverage begins with a review of circuits. Included in this review are buck,
buck-boost and boost regulators, and flyback, forward, half-bridge, bridge and
push-pull converters. Each circuit is illustrated well with a clear explanation of its
action and simple waveforms; the mathematical treatment is adequate but not
excessive, in keeping with the overall
approach of the book. Specialised convertors such as Cuk and various resonant
types are covered, but in less detail.
The impact of higher switching frequency on the size of transformers, induc-
tors and capacitors is set down rationally
and the implications for electromagnetic
interference are touched on. The treatment of wound components starts with
the basic laws, but the progression from
these to practical is weak. The illustrations
of production methods for cores add
interest, but these may become dated
rather quickly if switching frequencies in
SMPS equipments continue to rise in the
future. The design guidance given in this
section runs the risk of attempting to constitute a full manual.
The additional section on circuit simulation in this edition is welcome. A brief
introduction is given to SPICE, which is
the most widely used commercial software in this area. The section is brief but
sufficient as an introduction. The SABER
simulator is given a passing reference and
more comparative comment on these two
packages might have helped.
The explanation of the principles and
characteristics of diodes and MOSFETs is
given in appropriate detail, but an indica-
tion of future trends in this fast-developing field is missing and would have been
useful. Coverage of bipolar devices disappears in this edition because of the predominance in modern equipment of
MOSFETs. The treatment of control
appears thorough and soundly-based.
Increased treatment of electromagnetic interference is included in this second edition because of the effects of
tighter regulations. This is a difficult area
to cover at this intermediate level, but
screening and shielding are explained
well with reference to fundamentals and
useful guidance on filters and earthing is
included.
The final sections on production and
reliability emphasise the practical bias in
the whole book, which provides a useful
addition to the available published material and which should be present on the
bookshelf of all those involved in the
design and use of SMPS.
DOUG WARNE
Financial and economic evaluation of projects
in the electricity supply industry
Hisham Khatib
The Institution of Electrical Engineers, 1997, 199pp., £48, ISBN 0 85296 908 2
B
runel was reputed to have said: ‘An
engineer can do for a penny what any
fool can do for a pound’. True or otherwise,
there can be no doubt that all professional engineers should have a thorough
understanding of the different ways of
evaluating the financial and economic
characteristics of engineering projects.
Without these basic skills, it is all too easy
continually to deride the decisions of the
‘money men’ or ‘bean-counters’, yet not be
able fully to understand their arguments
or counter their influence. After buying
and reading this book, you will be better
able to understand the arguments, so as
to either beat the bean-counters on home
ground, or perhaps even occasionally
agree with them!
The author has succeeded in condensing a broad range of topics into a readable
book, whilst largely avoiding making a
complex subject either dry or dated in
style. Inevitably there are details one
could quibble with, such as the assertion
that investment risk in the electricity supply industry (ESI) ‘is lower than the average market equity’ (p.29), which is frequently untrue.
Yet it is the inclusion of a chapter covering the very topic or risk, coupled with
another giving a clear exposition of the
impact of discounting on the value of
money (or kWh) and the concept of net
present value (NPV) that helps make this
book worthwhile for a broad range of
readers. The author has also made a conscious effort to compare and contrast the
way different bodies (Governments,
multilateral agencies, environmentalists,
companies and banks) tend to look at the
same project or problem — this alone
made the book worthwhile for me, as I
was able to develop a fresh awareness of
the disagreements that arise by not
POWER ENGINEERING JOURNAL APRIL 1998
understanding alternative analyses of the
same problem.
Many lobbyists, consultants, commentators and participants in the ESI, with
strongly held views about the ‘right’
answer to the coal/nuclear/gas debate in
any particular country, would benefit
greatly from reading this book, although
in all probability the greatest benefit will
be gained by those in the early stages of
learning about discounting and financial
and economic analysis. If you already
know the difference between financial
and economic evaluation and understand precisely why least cost planning
often provides a sub-optimal solution,
then you may not need this book. If, like
me, your knowledge of these areas is
imperfect, the conclusion is simple — buy
it and read it.
NIGEL BURTON
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