29247 - Electrical Machines T

Learning outcomes

The course is proposed to supply the basic knowledge for the study of the widely used electric machines. The operating principles and the performance in different operating conditions will be analysed. After passing this course, students will be familiar with issues involved in electromechanical energy conversion, use of mathematical models to predict the machine behaviour, analysis of usual operating conditions.

Course contents

Prerequisites

Basic skills in electrical engineering.

Course contents

Introduction
Main properties of conducting, dielectric and ferromagnetic materials employed in electrical machines. Losses and heat dissipation.

Transformers
Single phase transformers: principle of operation, simplified mathematical model, eddy current losses in the core, mathematical model with eddy current losses, mathematical model with eddy current losses and core saturation, equivalent circuit referred to primary and referred to secondary, no load operating conditions, load operating conditions, rated operating conditions, transformer tests, transformer losses, parallel operation of transformers, structure, heat dissipation, measurement transformers, autotransformers.
Three-phase transformers: winding connections, mathematical model, equivalent circuit, structure, no load operating conditions, behavior with unbalanced loads, transformer tests, parallel operations, auto transformers.

DC machines
Introduction, magnetic circuit, field winding, armature winding, brushes and commutator, armature reaction, electromagnetic torque, mathematical model, commutation process, interpoles, compensating windings, circuit connections, torque/speed curves, permanent magnet DC machines.

Synchronous machines
Introduction, classification, principle of operation. Synchronous machines with round rotor: magnetic circuit, stator and rotor windings, analysis of the air-gap magnetic field, mathematical model under sinusoidal operating conditions, synchronous reactance, Behn-Eschemburg vectorial diagram, electromagnetic torque. Synchronous machines with salient pole rotor: magnetic circuit, mathematical model under sinusoidal operating conditions, synchronous reactances, Arnold-Blondel vectorial diagram, electromagnetic torque. Steady-state and dynamic stability limits, swing oscillations, damping windings. Grid connection of a synchronous generator. Introduction to permanent magnet synchronous machines.

Induction machines
Introduction, classification, principle of operation, magnetic circuit, stator and rotor windings, analysis of the air-gap magnetic field, slip, mathematical model under sinusoidal operating conditions, equivalent circuit, electromagnetic torque, torque/speed curve, induction machines with cage rotor, starting and speed regulation. Single-phase induction machines: principle of operation, mathematical model, equivalent circuit, starting problems.

Readings/Bibliography

It is not necessary to buy specific books. The pdf files of the slides utilized during the lessons are indispensable and sufficient for the preparation for the exam, and are available on IOL. For further considerations:

Title: Conversione elettrica ed elettromeccanica dell’energia
Authors: B. Brunelli
Editor: Pitagora (Bologna)

Title: Macchine elettriche
Authors: A. E. Fitzgerald, C. Kingsley, A. Kusko
Editor: Franco Angeli

Title: Costruzioni elettromeccaniche (Vol. I e II)
Authors: E. Di Pierro
Editor: Edizioni Scientifiche Siderea (Roma)

Title: Macchine elettriche
Authors: L. Fusco, D. Iannuzzi, E. Pagano, L. Piegari
Editor: Liguori Editori (Napoli)

Title: Electrical machines (Vol. I e II)
Authors: M. Kostenko, l. Piotrovsky
Editor: Mir Publishers (Moscow)

Title: The nature of polyphase induction machines
Authors: P. L. Alger
Editor: John Wiley and Sons (New York)

Teaching methods

The frontal lessons are supported by exercises with Personal Computer (MATLAB-Simulink, FEMM).

Assessment methods

The exam consists of an oral examination, which is based on four questions.

Teaching tools

Lessons are carried out with the help of a personal computer and a computer projector (Power Point). The pdf files of the slides utilized during the lessons are available on IOL. Exercises are carried out with the help of a personal computer (MATLAB-Simulink, FEMM).

Office hours

See the website of Angelo Tani