ELECTRICAL MACHINES

The course is aimed to provide the basic and advanced knowledge on electrical machines as required in modern applications and preliminary for the machine control. The study of the electrical machines will begin stating the operating principles of the machines and their equivalent circuits, therefore, it will continue with the study of the dynamic operation and models. About the rotating ac machines, also the equivalent circuit at qd0 will be introduced according to the generalized theory of electrical machines (or of the arbitrary references frames). After completing the course, the student will acquire the enabling knowledge for using the electric machines in static and dynamic loads in all industrial and civil applications with particular attention to energy saving, for example electrical traction, energy production and conversion, renewable energy.

Knowledge and understanding

Students will gain knowledge about the operating principles of the eletrical machines, about the construction characteristics and the static and dynamic models. Applications will be realitve to the production and distribution of electricity, civil and industrial systems, electric traction.

Applying knowledge and understanding

At the end of the course, the students will have the necessary skills to analyze an electric machine, identifying its parts and functions. Students will have the skills necessary for the characterization of systems and processes, the use of electrical machines, the evaluation of performance and the calculation of electrical quantities in steady state, transients and in case of failure.

Making judgements

Students will acquire independent judgment for an accurate analysis of electrical machines, these skills will also be enforced through experimental tests carried out in the laboratory and numerical simulations.

Communication skills

The students will strengthen the technical language of electric machines to be adeguate for the job with adequate skills and an adequate technical profile. The ability to work in groups will be refined through the experimental experiences in the laboratory carried out in small groups. The drafting of the laboratory report and the oral exam will allow you to refine your technical language and communication skills.

Learning skills

The students will be able to autonomously expand their knowledge of electrical machines through in-depth study of the reference texts, in articles in specialized scientific journals and through the ideas offered by the seminar activities organized by the teaching and by the degree course.

Class on Electrical Machines includes both lectures and laboratory activities. Whenever possible expert seminars will be organized with national and international speakers from industry and academia.

Should teaching be carried out in mixed mode or remotely, it may be necessary to introduce changes with respect to previous statements, in line with the programme planned and outlined in the syllabus.

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 E. Chiricozzi, A. Ometto, Aracne, 2017
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

The exam consists of an oral test. The oral exam typically consists of 3 main questions which are followed by an in-depth discussion on the subject. The final evaluation will take into account the acquired knowledge, skills, clarity of presentation and the property of technical language. The average duration of the oral exam is 90 min.

Verification of learning can also be carried out electronically, should the conditions require it.

• Principles of operation of the four machines.
  
• Tests on electric machines.
  
• Circuit at qd0 of the asynchronous machine and of the synchronous machine.
  
• Calculation of the tourque in steady state, expression of the torque in transient condition.