This Encyclopedia of Control Systems, Robotics, and Automation is a component of the global Encyclopedia of Life Support Systems EOLSS, which is an integrated compendium of twenty one Encyclopedias. This 22-volume set contains 240 chapters, each of size 5000-30000 words, with perspectives, applications and extensive illustrations. It is the only publication of its kind carrying state-of-the-art knowledge in the fields of Control Systems, Robotics, and Automation and is aimed, by virtue of the several applications, at the following five major target audiences: University and College Students, Educators, Professional Practitioners, Research Personnel and Policy Analysts, Managers, and Decision Makers and NGOs.

Control in Power Electronics explores all aspects of the study and use of electronic integrated circuits for the control and conversion of electrical energy. This technology is a critical part of our energy infrastructure, and supports almost all important electrical applications and devices. Improvements in devices and advances in control concepts have led to steady improvements in power electronic applications. This is driving a tremendous expansion of their applications. Control in Power Electronics brings together a team of leading experts as contributors. This is the first book to thoroughly combine control methods and techniques for power electronic systems. The development of new semiconductor power components, new topologies of converters from one side coupled with advances in modern control theory and digital signal processors has made this book possible and presents the applications necessary for modern design engineers. The authors were originally brought together to share research and applications through the international Danfoss Professor Programme at Aalborg University in Denmark. ersonal computers would be unwieldy and inefficient without power electronic dc supplies. Portable communication devices and computers would also be impractical. High-performance lighting systems, motor controls, and a wide range of industrial controls depend on power electronics. In the near future we can expect strong growth in automotive applications, dc power supplies for communication systems, portable applications, and high-end converters. We are approaching a time when all electrical energy will be processed and controlled through power electronics somewhere in the path from generation to end use.

Figure 1.1. An outdoor scene "A bus is passing three cars which are parking between trees at the side of the road. Houses having two storeys are lined up at the street. 3 4 Introduction Figure 1.2. An assembly scene There seems to be a small open place between the group of houses in the foreground and the store in the background". In such or a similar way the content of the natural scene shown above can be described. It is quite easy to give such a short description. The problem is somewhat more complex for the second image. First of all, it can be stated that the image does not show an everyday scene. It appears as a kind of man made surrounding. But everyone can accept the following statements about this image: 1. The image shows a snapshot of an assembly line. 2. The robot in front is screwing. 3. There is no person in the working area of the robots. 4. All objects on the conveyor belt are worked on by robots. There are no free objects on the belt.

2 e This book describes principles, methods and tools that are common to computer applications for design tasks. CAD is considered in this book as a discipline that provides the required know-how in computer hardware and software, in systems analysis and in engineering methodology for specifying, designing, implementing, introducing, and using computer based systems for design purposes. The first chapter gives an impression of the book as a whole, and following chapters deal with the history and the components of CAD, the process aspect of CAD, CAD architecture, graphical devices and systems, CAD engineering methods, CAD data transfer, and application examples. The flood of new developments in the field and the success of the first edition of this book have led the authors to prepare this completely revised, updated and extended second edition. Extensive new material is included on computer graphics, implementation methodology and CAD data transfer; the material on graphics standards is updated. The book is aimed primarily at engineers who design or install CAD systems. It is also intended for students who seek a broad fundamental background in CAD.