e_book:fundamentals_of_power_electronics [PowerPoint ver]

semico_ljj · 发表于 2007-1-29 08:40:33

In many university curricula, the power electronics field has evolved beyond the status of comprising one
or two special-topics courses. Often there are several courses dealing with the power electronics field,
covering the topics of converters, motor drives, and power devices, with possibly additional advanced
courses in these areas as well. There may also be more traditional power-area courses in energy
conversion, machines, and power systems. In the breadth vs. depth tradeoff, it no longer makes sense for
one textbook to attempt to cover all of these courses; indeed, each course should ideally employ a
dedicated textbook. This text is intended for use in introductory power electronics courses on converters,
taught at the senior or first-year graduate level. There is sufficient material for a one year course or, at a
faster pace with some material omitted, for two quarters or one semester.
The first class on converters has been called a way of enticing control and electronics students into the
power area via the "back door". The power electronics field is quite broad, and includes fundamentals in
the areas of
l Converter circuits and electronics
l Control systems
l Magnetics
l Power applications
l Design-oriented analysis

semico_ljj · 发表于 2007-1-29 08:41:45

This wide variety of areas is one of the things which makes the field so interesting and appealing to
newcomers. This breadth also makes teaching the field a challenging undertaking, because one cannot
assume that all students enrolled in the class have solid prerequisite knowledge in so many areas. Indeed,
incoming students may have individual backgrounds in the power, control, or electronics areas, but rarely
in all three. Yet it is usually desired to offer the class to upper-division undergraduate and entering
graduate students. Hence, in teaching a class on converters (and in writing a textbook), there are two
choices:
1. Avoid the problem of prerequisites, by either (a) assuming that the students have all of the
prerequisites and discussing the material at a high level (suitable for an advanced graduate class),
or (b) leaving out detailed discussions of the various contributing fields.
2. Attack the problem directly, by teaching or reviewing material from prerequisite areas as it is needed. This material can then be directly applied to power electronics examples. This approach
is suitable for a course in the fourth or fifth year, in which fundamentals are stressed.
Approach (2) is employed here. Thus, the book is not intended for survey courses, but rather, it treats
fundamental concepts and design problems in sufficient depth that students can actually build converters.
An attempt is made to deliver specific results. Completion of core circuits and electronics courses is the
only prerequisite assumed; prior knowledge in the areas of magnetics, power, and control systems is helpful but not required.
In the power electronics literature, much has been made of the incorporation of other disciplines such as
circuits, electronic devices, control systems, magnetics, and power applications, into the power
electronics field. Yet the field has evolved, and now is more than a mere collection of circuits and
applications linked to the fundamentals of other disciplines. There is a set of fundamentals that are
unique to the field of power electronics. It is important to identify these fundamentals, and to explicitly
organize our curricula, academic conferences, and other affairs around these fundamentals. This book is
organized around the fundamental principles, while the applications and circuits are introduced along the
way as examples.

semico_ljj · 发表于 2007-1-29 08:43:18

A concerted effort is made to teach converter modeling. Fundamental topics covered include:
l Fundamentals of PWM converter analysis, including the principles of inductor volt-second balance and capacitor
charge balance, and the small-ripple approximation (Chapter 2).
l Converter modeling, including the use of the dc transformer model, to predict efficiency and losses (Chapter 3).
l Realization of switching elements using semiconductor devices. One-, two-, and four-quadrant switches. A brief
survey of power semiconductor devices (Chapter 4).
l An up-to-date treatment of switching losses and their origins. Diode stored charge, device capacitances, and
ringing waveforms (Chapter 4).
l Origin and steady-state analysis of the discontinuous conduction mode (Chapter 5).
l Converter topologies (Chapter 6).
l The use of averaging to model converter small-signal ac behavior. Averaged switch modeling (Chapter 7).
l Converter small-signal ac transfer functions, including the origins of resonances and right half-plane zeroes.
Control-to-output and line-to-output transfer functions, and output impedance (Chapter 8).
l A basic discussion of converter control systems, including objectives, the system block diagram, and the effect of
feedback on converter behavior (Chapter 9).
l Ac modeling of the discontinuous conduction mode. Quantitative behavior of DCM small-signal transfer functions
(Chapter 10).
l Current-programmed control. Oscillation for D > 0.5. Equivalent circuit modeling (Chapter 11).
l Basic magnetics, including inductor and transformer modeling, and loss mechanisms in high-frequency power
magnetics (Chapter 12).
l An understanding of what determines the size of power inductors and transformers. Power inductor and
transformer design issues (Chapters 13 and 14).
l Harmonics in power systems (Chapter 15).
l A modern viewpoint of rectifiers, including harmonics, power factor, and mitigation techniques in conventional
rectifiers, and operation of sophisticated low-harmonic rectifiers (Chapters 16-18).
l Analysis and modeling of low-harmonic rectifiers (Chapters 17-18).
l Resonant inverters and dc-dc converters: approximate analysis techniques, characteristics of basic converters, and load-dependent properties (Chapter 19).
l Zero voltage switching, zero current switching, and the zero-voltage-transition converter (Chapter 19).
l Resonant switch converters, including basic operation, efficiency and losses, and ac modeling (Chapter 20).
On teaching averaged converter modeling: I think that this is one of the important fundamentals of the
field, and hence we should put serious effort into teaching it. Although we in the academic community
may debate how to rigorously justify averaging, nonetheless it is easy to teach the students to average:
Just average all of the waveforms over one switching period. In particular, for the continuous conduction
mode, average the inductor voltages and capacitor currents over one switching period, ignoring the
ripple. That's all that is required, and I have found that students quickly and easily learn to average
waveforms. The results are completely general, they aren't limited to SPDT switches, and they can easily
be used to refine the model by inclusion of losses, dynamics, and control variations. To model dynamics,
it is also necessary to linearize the resulting equations. But derivation of small-signal models is nothing
new to the students --they have already seen this in their core electronics classes, as well as in numerous
math courses and perhaps also in energy conversion. It isn't necessary to teach full-blown state-space
averaging, but I have included an optional (with asterisk) section on this for the graduate students. I
personally prefer to initially skip Sections 7.4 and 7.5. After covering Chapters 8 and 9, I return to cover
Sections 7.4 and 7.5 before teaching Chapters 10 and 11.