Machines & Electrical Drives (ENT 223/3)

This book discusses the state-of-the art of electric machines, associated components and contemporary trends of their development. Novel electric machines considered in this book have been limited to rotary electric machines. Linear electric machines and linear actuators have not been included. This volume has three main objectives: (1) Firstly, to promote electrical machines as the most popular machines of everyday life and increase awareness in this area; (2) Secondly, to stimulate innovations in electrical machines and electromechanical drives; (3) Thirdly, to help educators revitalize Power Engineering curricula and change research strategy towards what industry and mankind needs.

Electrical drives consist of a number of components, the electrical machine, converter and controller, all of which are discussed at various levels. A brief resume of magnetic and electrical circuit principles is given in chapter 1 together with a set of generic building modules which are used throughout this book to represent dynamic models. Chapter 2 is designed to familiarize the reader with the process of building a dynamic model of a coil with the aid of generic modules. This part of the text also contains an introduction on phasors as required for steady state analysis. The approach taken in this and the following chapters is to present a physical model, which is then represented by a symbolic model with the relevant equation set. A generic model is then presented which forms the basis for a set of build and play simulations set out in various steps in the tutorial at the end of the chapter. Chapter 3 introduces a single phase ideal transformer (ITF) which forms the basis of a generic transformer model with leakage and magnetizing inductance. A phasor analysis is given to familiarize the reader with the steady state model. The build and play tutorials at the end of the chapter give the reader the opportunity to build and analyse the transformer model under varying conditions. It is emphasized that the use of these build and play is an essential component of the learning process throughout this book. Chapter 4 deals with star and delta connected three phase systems and introduces the generic modules required to model such systems. The space vector type representation is also introduced in this part of the text. A set of build and play tutorials are given which reinforce the concepts introduced in this chapter. Chapter 5 deals with the concepts of real and reactive power in single as well as three phase systems. Additional generic modules are introduced in this part of text and tutorial examples are given to familiarize the reader with this material. Chapter 6 extends the ITF concept introduced earlier to a space vector type model which is represented in a symbolic and generic form. In addition a phasor based model is also given in this part of the text. The build and play tutorials are self-contained step by step simulation exercises which are designed to show the reader the operating principles of the transformer under steady state and dynamic conditions. At this stage of the text the reader should be familiar with building and using simulation tools for space vector type generic models which form the basis for a transition to rotating electrical machines. Chapter 7 introduces a unique concept namely the ideal rotating transformer (IRTF), which is the fundamental building block that forms the basis of the dynamic electrical machine models discussed in this book. A generic space vector based IRTF model is given in this part of the text which is instrumental in the process of familiarizing the reader with the torque production mechanism in electrical machines. This chapter also explores the conditions under which the IRTF module is able to produce a constant torque output. It is emphasized that the versatility of the IRTF module extends well beyond the electrical machine models discussed in this book.These advanced IRTF based machine concepts are discussed in a second book Advanced electrical Drives currently under development by the authors of this text. The build and play tutorials at the end of thischapter serve to reinforce the IRTF concept and allow the reader to play with the conditions needed to produce a constant torque output from this module. Chapters 8-10 deal with the implementation of the IRTF module for synchronous, asynchronous and DC machines. In all cases a simplified IRTF based symbolic and generic model is given of the machine in question to demonstrate the operating principles. This model is then extended to a full dynamic model as required for modelling standard electrical machines. A steady state anal