# Electromechanical Energy Conversion

## Objectives

Students must learn the fundamental concepts of the Electromechanical Energy Conversion in electromechanical systems.

The focused converter machines are the asynchronous, the synchronous and the direct-current machines, specially their constitution and their characteristics, both as generators and as motors.

The students must learn these machines’ operation and how to handle them in industrial environment.

## General characterization

11068

6.0

##### Responsible teacher

Anabela Monteiro Gonçalves Pronto

Weekly - 5

Total - 69

Português

### Prerequisites

The students must have:

• Frequency of Física III (Electromagnetism)
• Frequency of Eletrotecnia Teórica (Theory of Electrotechnics)

They should have acquired solid knowledge in the above areas.

### Bibliography

- Guru, B., Hiziroglu, H., Electric Machinery and Transformers, Oxford University Press, 3rd Ed., 2001

- Notes on "Máquina Assíncrona", prof. Ventim Neves, FCT/UNL

- Electromechanics and Electric Machines, S. A. Nasar

-- Electric Machinery Fundamentals, Stephen J. Chapman

- Dynamic Simulation of Electric Machinery, C. M. Ong

-  An Introduction to Electric Machines and Transformers, McPherson

### Teaching method

The matter is taught in theoretical and practical classes, with the support of projected figures and schematics. During a 2h weekly practical class, students either solve with the help of the teacher problems illustrating the exposed matters, or execute laboratorial works. In the laboratory-practical classes, the students either solve problems related to the exposed matter or carry out laboratory work with the teacher''''s support.Written tests (during the semester) or a final written examination, with theoretical and practical questions, are made by the students.

### Evaluation method

The evaluation method could be one of the following:

a) 2 Minitests (MT) + 2 Labortory Work (TL)

Mark (MT) = (0,40*MT1+0,60*MT2) >= 9,5 val.

Mark(TL)=(0,50*TL1+0,50*TL2)>=10,0 val. where TL1>= 10,0val and TL2>= 10,0 val

Final Mark = 0,75*Mark(MT) + 0,25*Mark(TL) >= 9,5 val.

b) Final Exam (Ex) + 2 Labortory Work (TL)

Final Ex. Mark  >= 9,5 val.

Mark(TL)=(0,50*TL1+0,50*TL2)>=10,0 val. where TL1>= 10,0val and TL2>= 10,0 val

Final Mark = 0,75*Mark(MT) + 0,25*Mark(TL) >= 9,5 val.

In either case, the student will be approved if, and only if, his/her grade is equal to or higher than 9.5 (scale 0 to 20).

If teachers considered so, any of the evaluation elements could be subjected to oral discussion.

Students with practical component already concluded and approved in 2019/2020 will be dismmed of doing it again, if they wish. In any case, students must inform the teacher about their decision: if they want to keep the previous mark or to repeat the laboratory component.

## Subject matter

- Foundations of the electromechanical energy conversion. Electrical, magnetic and Mechanical energies. Virtual works principle. Force and Torque

- Rotating Field Machines. Magnetic Circuit. Air-gap field. Induction coefficients. Pulsating and Rotating fields. Synchronous and Assynchronous Machines.

- Assynchronous machine. Constitution. Operation. Equations. Equivalent Schematic circuit. Speed and Torque. Circle diagram. Speed control. Principle of the two-axis transform.

- Synchronous Machine. Cilindrical and salient-poles rotors. Coeficients. Equations and Schematics. Alternator-Grid parallel. Active and reactive power flow. Characteristics. Rotor oscillations. Damping windings. Sudden symmetrical short-circuit. Transient and sub-transient time constants. Synchronous motor. Starting. Synchronous compensator.

- Direct current Machine. Constitution. “Lap” and “Wave” windings. Armature magnetic reaction. Auxiliary poles. Types of excitation. Generators and motors characteristics. Electric traction. Speed control. Dynamic regime.

## Programs

Programs where the course is taught: