69659 - ELECTRIC DRIVES FOR AUTOMATION M

Learning outcomes

The aim of this course is to present advanced problems concerning electrical drives and power electronics for energy conversion. The main topic of the course is the control of high-performance vector drives and power converters used in typical industrial applications, and in more recent applications, such as wind energy plants, solar plants and electric vehicles. The main topics presented in the course are d-q models of electrical machines, fundamentals of the voltage modulation in power converters, modern control schemes for induction machines, anisotropic synchronous machines, reluctance motors and linear actuators, back-to-back converters, UPS and active filters, and their applications in modern smart grids. At the end of the course the students have a deep insight about electrical drives and their advanced control schemes, and know basic tools and technologies for energy conversion. The course requires a previous knowledge of the fundamentals of electrical machines and power electronics. Power electronic fundamentals are given in the course “Power Electronic Circuits M”.

Course contents

Advanced motors
- brushless motors with surface PM
- brushless motors with inner PM
- induction motors with squirrel-cage rotor
- doubly-fed induction motors

Brushless AC motor drives

Dynamic model of permanent magnet synchronous machines with surface mounted magnets. The dq machine and flux equations. Principles of field orientation. Torque production and control. Dynamic model of permanent magnet synchronous machines with interior magnets. The dq machine and flux equations. Torque production and control. Control of the synchronous machine supplied by current-controlled PWM inverter. Simulation of electromechanical transients. Maximum torque capability of the machine in the flux weakening region.

Induction motor drives

Analysis of induction motors based on a steady-state machine model. Torque and machine equations. Steady-state characteristics. Starting of induction motors. Dynamic model of induction machines. The dq machine and flux equations. Torque equation. Principles of field orientation. Machine equations and torque in the rotor flux oriented reference frame. Decoupling control of flux and torque in the rotor flux oriented reference frame.  Direct and indirect control schemes for field-oriented control of induction motors. Control of the induction machine supplied by current-controlled PWM inverter. Simulation of electromechanical transients. Maximum torque capability of the machine in the flux weakening region. Applications.

Elements of power electronics

-Space vectors
-Inverter with vector control
-Back-to-back converter
-Modulation strategies
-Active filters
-Fundamental of electric drives and power electronics converters for Smart Grid and renewable sources.

Current regulators for electric drives

- Synchronous PI regulators
- Resonant PI regulators
- Dead-beat control
- Repetitive control

Fundamentals of wind energy systems

- Structure of a wind turbine. Power of the wind. Power coefficient. Betz's limit. Maximum power point tracking. Speed control. Power control at high wind speed. Wind energy systems based on PM generators and induction generators.

Readings/Bibliography

Charles Kingsley, Stephen Umans, A Fitzgerald: Electric Machinery, McGraw-Hill Education.
I. Boldea, S. A. Nasar: ELECTRIC DRIVES, CRC Press, New York.
P. Vas: VECTOR CONTROL of AC MACHINES, Oxford University Press, New York.
Bimal Bose: MODERN POWER ELECTRONICS AND AC DRIVES, Prentice-Hall.
T.J.E. MILLER, Brushless permanent-magnet and reluctance motor drives, Clarendon Press, Oxford, 1989.

Teaching methods

The lessons are in ENGLISH. During the course, the students learn how to solve some simple numerical exercises. Finally, some Simulink models of electric drives and power converters are shown.

 

Assessment methods

The exam consists of a written test, an oral test (on request), and the discussion of a drive project (optional).

The written test lasts 2 hours and is designed to verify the students' preparation for the entire program, their ability to condense the most important concepts in a limited time, and to use the learned equations.

If the result of the written test is sufficient (> = 18), the student can

- immediately record the score

- repeat the written test to improve the result (the previous positive scores are NOT lost).

- present a project, chosen from a list provided by the Professor for a slight improvement. Each project has a pre-assigned score (2-3 points) and the final grade results from the sum of the two parts.

If the result of the written test is> = 14 points (the grade is sufficient, or it is sufficient but the student is not satisfied), instead of repeating the written test, the student can take an "in-depth" oral exam. During this test, the student will be asked about the entire program (generally 45-60 minutes): 5 questions are assigned, some time is left to think and write the fundamental equations and schemes. Then, there is a discussion aimed at ascertaining the student's knowledge. The final grade is the average of the written and oral tests.

Teaching tools

The slides of the course and the Simulink models are available on IOL.

The password is given by the professor at the beginning of the course.

Links to further information

http://www.die.ing.unibo.it/automazione/

Office hours

See the website of Luca Zarri