Preface

Induction motors research has a long and distinguished tradition stretching back to the end of the nineteenth-century with the pioneering works of Nikola Tesla. Its establishment as the main type of electric motor used in electric drives in the 1990s arose, essentially, following the early works of Blaschke and Hasse on Field-Oriented Control methods by, among others, Professors Leonhard and Lipo. All this has been increasingly underpinned by the rapid developments in computing capability and power electronics. Modern variable-speed drives rely on sophisticated control systems to meet increased performance and communication requirements. Presently, the variable-speed drives with induction motor remains the dominant market leader in a large range of industrial applications.

In broad terms, the electromechanical energy conversion can occur only by the interaction of electromagnetic fields and material bodies in motion, then it is reasonable to begin with a treatment that the task of an induction motor is to produce motive force, which can be controlled by power electronic converters with digital controllers to implement modern variable-speed drives. This unit must be controlled in harmony with the industrial processes in which the drive is applied. Historically, from the point of view of practical application, a significant amount of research on induction motor drives was motivated by industrial applications. This book aims to provide the readers with a deep discussion about relevant topics in the area of induction motor drives. There are several good books in the area of electric drives. At the same time, as a result of the increasing interest raised by the subject, a large number of technical methodological papers began to appear in the technical literature. However, this book borrows from these cited works and hopefully makes its own contribution to the literature on induction motors. The book contains twenty-one chapters, which are authored by international researchers in the field from Europe, South America, Japan and the USA. The book is organized into two parts. First part presents different views about mathematical description in terms of which transient states of an induction machine are analyzed, and explores some topics related to design of the induction motor and its applications. This part ends with a chapter on how to identify the induction motor parameters using a least-squares technique. Second part covers the control of induction motors presenting both field-oriented techniques and nonlinear control methods. The direct torque control and sensorless

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methods are also presented, along with simulations results. The last chapters address the problem of how to detect induction motor faults. Particularly, the use of direct spectral analysis of stator current to find rotor faults, which has important practical applications, is presented.

In closing, I would like to express thanks to the chapter contributors for their cooperation and patience in various stages of the book. Special thanks are directed to friends and colleagues who have helped in the chapter review and selection process. These include Ângela Ferreira, André Mendes, Claudio Vergara, Pedro Melo, Ricardo Castro, Ventim Neves, and Vicente Leite. Special mention is due to my wife Manuela Araújo for the invaluable assistance, both tangible and intangible, given during the implementation of this project.

I am very grateful to all the people who were involved in the preparation of this book at Intech Europe, especially Ms. Alida Lesnjakovic and Ms. Romina Skomersic for their support and patience.

> **Rui Esteves Araújo** Faculdade de Engenharia da Universidade do Porto, Portugal

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applications, is presented.

implementation of this project.

support and patience.

methods are also presented, along with simulations results. The last chapters address the problem of how to detect induction motor faults. Particularly, the use of direct spectral analysis of stator current to find rotor faults, which has important practical

In closing, I would like to express thanks to the chapter contributors for their cooperation and patience in various stages of the book. Special thanks are directed to friends and colleagues who have helped in the chapter review and selection process. These include Ângela Ferreira, André Mendes, Claudio Vergara, Pedro Melo, Ricardo Castro, Ventim Neves, and Vicente Leite. Special mention is due to my wife Manuela Araújo for the invaluable assistance, both tangible and intangible, given during the

I am very grateful to all the people who were involved in the preparation of this book at Intech Europe, especially Ms. Alida Lesnjakovic and Ms. Romina Skomersic for their

**Rui Esteves Araújo**

Portugal

Faculdade de Engenharia da Universidade do Porto,

**Section 1** 

**Modelling** 

**Section 1** 
