Electromechanical Energy Conversion


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





Responsible teacher

Pedro Miguel Ribeiro Pereira


Weekly - 5

Total - 69

Teaching language



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.


 - 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


Includes a theoretical component (Comp. TP) and a practical component (Comp. P), with weights of 80% and 20%, respectively, for the final classification. The classification in each component (TP and P) must be greater than 9,5.

Comp. P - Two experimental works (TA1 and TA2), whose classification must be greater than or equal to 9.5 and is mandatory for obtaining frequency.

Comp. TP - can be made by:

 a) 3 Tests (T)

 Classif. Comp. TP = (0,30*T1 + 0,35*T2 + 0,35*T3)  >=  9,5 val.

  with T3 >= 7,0 val.

  b) Final Exam (Ex)  >=  9,5 val.

The final grade is obtained by:

                  NF = (0.80 * Comp.TP) + (0.10 * TA1 + 0.10 * TA2​​)

The classification obtained for experimenatl work is valid for 2 years.

ONLY numerical calculators will be allowed during tests and/or exams.

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 where the course is taught: