# 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 - 4

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 2021/2022 will be dismissed of doing it again, if they wish. Students must inform the teacher only if they want to repeat the laboratory component.

The evaluation procedure in exactly the same for ERASMUS students.

## 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: