Fundamentals of Power Electronics 3rd ed

Book Preface

The objective of the First and Second Editions was to serve as a textbook for introductory power electronics courses where the fundamentals of power electronics are defined, rigorously presented, and treated in sufficient depth so that students acquire the knowledge and skills needed to design practical power electronic systems. An additional goal was to contribute as a reference book for engineers who practice power electronics design, and for students who want to develop their knowledge of the area beyond the level of introductory courses. In this Third Edition, the basic objectives and philosophy of the earlier editions have not been changed. Since we wrote the Second Edition, the field of power electronics has grown tremendously, including new significant commercial applications such as electric vehicles, wireless power transfer, and utility microgrids. Technical growth includes the commercialization of wide bandgap power semiconductors, widespread digital control of switching converters, and maturation of converter modeling. Our university power electronics curriculum has evolved as well, in content as well as in organization. This edition is a response to these changes, and represents a significant revision relative to the previous edition.

As of 2020, at the University of Colorado we offer a sequence of three core graduate courses in power electronics. The first course, Introduction to Power Electronics, covers basic converter analysis, converter controllers, and magnetics. In the Third Edition, this material is presented in Chaps. 1–12, at the level and in the order covered in this class. Our second course, Modeling and Control of Power Electronics Systems, covers more advanced topics of power converter applications, control, and design-oriented analysis.

This material is covered in detail in Chaps. 13–21 in the Third Edition; this portion of the text represents a major revision of technical material and coverage. Our third course, Resonant and Soft Switching Phenomena in Power Electronics, relies primarily on supplementary notes rather than this textbook. Chapters 22 and 23 of the Third Edition cover a summary of a portion of this third course. The coverage of power semiconductor devices in Chap. 4 has been bolstered and updated. The discussion of power diode switching has been significantly expanded, leading into averaged modeling of diode-induced switching loss.

New material on wide bandgap devices and on MOSFET gate drivers has been added. The discussion of switching loss mechanisms has been updated and reorganized, and the MCT section is removed.
The Third Edition adopts a more mature viewpoint of averaging, based on the trapezoidal moving average defined in Eq. (7.3). The waveforms of the averaged model become true continuous quantities, with the approximations and logical steps clearly defined. New material in Chap. 7 includes a section on the averaging operator, and a new treatment of how the smallripple approximation works with the trapezoidal moving average. Additionally, the logical flow of Chap. 7 has been significantly revised to conform to how we now teach this material in our on-campus courses, and new material on state-space averaging has been added. This new viewpoint of averaging then is followed throughout the remainder of the book. Of most note, this viewpoint leads to the current-programmed control model of Tan and Middlebrook. The currentprogrammed control Chap. 18 has been significantly revised and updated accordingly. The highfrequency effects of sampling are discussed as well, in connection with current-programmed control and also with ac modeling of the discontinuous conduction mode.

The previous treatment of stability and phase margin would leave some students with misconceptions; to alleviate this, we have introduced a new section on Nyquist stability. Instructors may choose whether there is time to cover this material in a power electronics course, but the explanation is available as a reference in the text. The origin of the phase margin text is rigorously explained, and special cases such as conditionally stable systems or those with multiple crossover frequencies are adjudicated. A new section in the chapter on input filters has been added, which relies on the Nyquist stability criterion to determine the exact stability boundary in the presence of an input filter.

An all-new Part IV Advanced Modeling, Analysis, and Control Techniques has been organized to follow the logical flow of our advanced converter control course, and incorporates new chapters on null double injection techniques (Middlebrook’s feedback theorem and extra ele ment theorem) and on digital control of switching converters. The topics of circuit averaging, average switch modeling, and averaged simulation are consolidated into a single logical chapter. New examples of the extra element theorem include solution of the SEPIC averaged switch model, and damping the internal resonances of the SEPIC.

Chapter 18 on current-programmed control has been significantly revised and reorganized. As noted above, it now employs the model of Tan and Middlebrook, using the trapezoidal moving average. New sections on simulation, sampling and high-frequency dynamics, and input filters are incorporated into the chapter. A new section on average current-mode control has also been added.

The new Chap. 19 on digital control of switching converters extends the analog control techniques of earlier chapters, to address the relevant issues of digital controllers. Quantization, sampling, and controller delays are modeled. The Z-transform is employed to model the discrete-time portion of the feedback loop, with the Laplace transform used as usual for the remaining analog system. Digital compensator design and realization is then addressed.

This text has evolved from courses developed over thirty-five years of teaching power electronics at the University of Colorado. These courses, in turn, were heavily influenced by our previous experiences as graduate students at the California Institute of Technology, under the direction of Profs. Slobodan Cuk and R. D. Middlebrook, to whom we are grateful. We would ´ also like to thank the many readers of the First and Second Editions, students, and instructors who offered their comments and suggestions, or who pointed out errata. We have attempted to incorporate these suggestions wherever possible.

Boulder, CO, USA Robert W. Erickson
Boulder, CO, USA Dragan Maksimovi