78761 - Electric Drives for Renewables M

Learning outcomes

The aim of the course is to provide a general approach to an understanding of the performance and control of electric machines and drives. After the course, the students are able to model and simulate dc motor drives, brushless motor drives and induction motor drives having clear knowledge of the physical aspects of electric machines behaviour when operating as motors and generators as well as the mathematical models of electric machines valid for steady-state and transient analysis.

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 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. Flux models. Direct scheme and indirect scheme of induction motor field oriented control. 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.

Fundamentals of electric vehicles

- Structure of an electric and hybrid vehicle. Topologies of hybrid vehicles. Model of a tire. Simplified model of a vehicle.

 

Readings/Bibliography

A.E. FITZGERALD, C. KINGSLEY JR., A. KUSKO, Macchine Elettriche, Franco Angeli Editore, Milano, 1978.
JOHN M.D. MURPHY, F.G. TURNBULL, Power Electronic Control of AC Motors, Pergamon Press, Oxford, 1988.
TAKASHI KENJO, Stepping motors and their microprocessor controls, Clarendon Press, Oxford, 1985.
T.J.E. MILLER, Brushless permanent-magnet and reluctance motor drives, Clarendon Press, Oxford, 1989.
T.J.E. MILLER, Switched reluctance motor and their control, 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 vote

- repeat the written test to improve the result (the previous positive vote is 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 is the sum of the two partial results.


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 reason and write the fundamental equations, then it starts 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.

Links to further information

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

Office hours

See the website of Luca Zarri