Power Electronics

Abstract

The field of electrical engineering is generally segmented into three major areas electronics, power and control. Power electronics is a combination of these three areas. In broad terms, the function of power electronics is to process and control the electrical energy by supplying voltage and current in a form that is optimally suited to the load. The advent of power semiconductor devices, thyristors, in 1957, has been an exciting breakthrough in the art of electric power conversion and its control. Power electronics has undergone intense technological evolution during the last three decades. Starting with the conventional thyristor-type devices in early days, the recent availability of high-frequency, high-power, MOS-gated self-controlled devices are opening new frontiers in the field. In modern power electronics equipment, there are essentially two types of semiconductor elements: the power semiconductors that can be considered as the muscles of the equipment, and the microelectronics control chips that provide power to the brain. Both the elements are digital in nature, except that one manipulates power upto gigawatts and the other handles only miliwatts. The close coordination of this end of the spectrum of electronics offers reduced size, cost advantages and high-level of performance. The market demands on industry for productivity and quality are increasing. This has resulted in an increasing demand for automation in production processes and hence in the use of variable speed drives. The use of electric cars, electric trams and electric subway trains can substantially reduce urban pollution problems. Power electronics permits generation of electric power from environmentally clean photovoltaic, fuel cells and wind energy sources. Widespread application of power electronics, with an eye for energy conservation and generation of power from environmentally clean sources, can help in solving problems like acid rains and greenhouse effects. This textbook presents the basic tools for the analysis and design of power electronic circuits and provides methods and procedures suitable for a variety of power electronic applications. This text is suitable for undergraduate-level courses in power electronics and/or electrical machines and drives. It is also intended for xvi Preface to the Second Edition practicing engineers who wish to gain knowledge of the recent developments in this rapidly expanding field. In response to the comment and suggestions from students and teachers, several changes in the presentation of topics have been made and new topics have been included in this revised edition of the book. The second edition offers several improvements over the first edition. Many sections have been rewritten to further simplify the presentation. Several chapters have been revised by adding new updated material. New problems have been formulated for many chapters. The book consists of 16 chapters. Two chapters (Chapters 1 and 12) are newly added and the sequence of chapters has been modified for better flow of the content. The following is a brief description of the topics that are covered in each chapter with an emphasis on the revisions that have been made in the second edition.