ELECTRICAL MACHINES

Il corso ha lo scopo di fornire conoscenze di base ed avanzate sulle macchine elettriche, in linea con quanto richiesto nelle moderne applicazioni e propedeutiche per il controllo. Lo studio delle macchine elettriche inizierà richiamando i principi di funzionamento delle macchine ed i relativi circuiti equivalenti a regime, quindi, proseguirà con lo studio dei modelli in transitorio ricavati secondo la teoria generalizzata delle macchine elettriche (o dei riferimenti arbritari). Al termine del corso, lo studente avrà acquisito le conocscenza che gli permettaranno di utilizzare le macchine elettriche in regime statico e dinamico in tutte le applicazioni industriali e civili quali la trazione elettrica, la produzione e conversione d'energia, anche da fonti rinnovabili, e con particolare attenzione al risparmio energetico.

Frontal lectures on theory topics carried out by a video projector. Exercises performed in the classroom by video projector using numerical simulation software. Collective activity of numerical exercises. Test laboratory for electrical machines.

The knowledge of the courses of Physics II and Electrotechnics are requested. It is suggested to have also the knowledge of a basic course on Electrical Machines dealing with steady state.

The frequency of the lessons is mandatory. Please note that the minimum rate of frequency is fixed at 70%.

Topic 1: Fundamentals of Electric Circuits (review)

• Phasor theory
• Three-phase circuits
• Real, reactive and complex power

Topic 2: Magnetic Circuits and Magnetic Materials

• Flux Linkage, Inductance and Energy
• Electromechanical- Energy-Conversion Principles
• Heating

Topic 3: Transformers

• Single phase and three-phase transformer
• Principles of operation
• Steady-state equivalent circuits
• No-load and short-circuit condition

Topic 4: Introduction to Rotating Machines

• Principles of operation and steady-state equivalent circuits of a dc machine
• Speed-Torque characteristics of a separately excited dc machine
• Space-phasor theory: the dq0 transformation
• Rotating magnetic field

Topic 5: AC Machines

• Principles of operation and steady-state equivalent circuits of a synchronous machine
• Theory and models of synchronous machine with and without saturation: Behn-Eshemburg, Potier, qd axes, Arnold-Blondel
• Capability curves of a synchronous machine
• Principles of operation and steady-state equivalent circuits of an induction machine
• Speed-Torque characteristics of an induction machine
• Model of synchronous and induction machines in qd0 reference frame
• Torque equations

1. Electric Machinery by A. E. Fitzgerald, C. Kingsley, Jr., S. D. Umans. , 7th Edition, McGraw-Hill, 2013
2. Electric Machinery Fundamentals by Stephen J. Chapman, 4^th Edition, McGraw-Hill, 2005
3. Macchine Elettriche by S. Crepaz, CittàStudi, 1996
4. Analysis of electric machinery by P.C. Krause, Mc Graw Hill, 1986
5. Electrical Machines voll. l e 2 by M. Kostenko, L. Piotrovski, MIR Mosca libreria Italia-URSS
6. Macchine Elettriche by A. Consoli, Notes
7. Slides presented at the lessons

Oral examination

- Explain fully the working principle of the buck converter with the help of schematic and equivalent circuit diagrams;

- Describe the main characteristics of the output voltage In a 3 phase bridge rectifier;

- Provide a detailed study of step - down dc choppers