37064 - Electrical Controls T

Learning outcomes

The aim of this course is to present the behavior of modern electrical drives. DC and AC electrical drives will be analyzed and their use in automation engineering will be presented. The main topics are dc motors, ac induction motors, brushless motors, stepper motors. The use of power converters for the control of torque, position and speed will be analyzed. Finally, the design and the selection criteria of the most suitable drive for a given application will be considered.

 

Course contents

Please, note that the couse is divided into two parts, and there are two different professors.

PART I
Fundamentals of Electric Machines (Prof. Fiorenzo Filippetti, 3 credits)

Introduction
Fundamentals of electromechanical energy conversion, generation of forces and torque in electrical machines, energy balance principles.

Synchronous Motors
Operating principles. Model and equations. Steady-state behavior.

Induction Motor
Operating principles. Model and equations. Steady-state behavior.

 

PART II
Fundamentals of Electric Drives (Prof. Luca Zarri, 6 credits)

DC Motor Drives
Separately excited DC machines. Mathematical model. Steady state characteristics with armature and field control. Control of DC motors in the armature control region and in the field-weakening region. Transition from driving to breaking operation. DC drives with line-commutated converters. DC drives with force-commutated converters. Single-, double-, and four-quadrant operation. Constant torque and constant horsepower operation. Application DC motor drives.

Brushless DC Motors
Magnetic circuit analysis. Torque and e.m.f. equations. Winding inductances and armature reaction. Torque/speed characteristics: performance and efficiency. The three-phase half-wave brushless DC motor. The three-phase full-wave brushless DC motor. Commutation phenomena. Position sensors. Drive characteristics and control principles. Application of brushless DC motor drives.

Synchronous Motor Drives
Magnetic circuit analysis of synchronous machines with surface-mounted magnets and with interior magnets. Synchronous reactances (d-, q-axis). Torque and machine equations. Steady-state characteristics. Open-loop control of voltage source inverter drives. Closed-loop control of current controlled PWM inverter drives. Synchronous motor drives with load-commutated inverter. Applications.

Induction Motor Drives
Analysis of induction motors based on steady-state machine model. Torque and machine equations. Steady-state characteristics. Starting of induction motors. Constant terminal volts/hertz operation. Torque characteristics. Low-frequency performance with increased volts/hertz. Constant air-gap flux operation. Torque characteristics. Current-source inverter drive with slip frequency control. Current controlled PWM inverter drive with slip frequency control. Constant-horsepower operation. Applications.

Stepping Motors
Classification of stepping motors. Stepping motors characteristics. Tooth structure, number of teeth, steps per revolution, and number of poles. Static torque production in variable reluctance stepping motor. Static torque production in hybrid stepping motors. Single-step response. Torque versus speed characteristics. Resonances and instabilities. Open-loop control of stepping motors. Logic sequencers. Motor drivers. One?phase on and two-phase on excitation. Half-step operation. Application of stepping motors.

Readings/Bibliography

For the first part:

- A.E. FITZGERALD C. KINGSLEY JR. A. KUSKO: MACCHINE ELETTRICHE, FRANCO ANGELI ED. MILANO
- F. CIAMPOLINI: ELETTROTECNICA GENERALE, PITAGORA ED. BOLOGNA
- notes of the teacher

For the second part:

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. 

Assessment methods

The exam is divided into two parts. The first one is related to the fundamentals of electric machines, the second one is related to electric drives.

Part I:
Written and oral exam.

Part II:
Written exam on the theoretical topics and presentation of a report on the laboratory activity.

Teaching tools

The course is integrated with some case studies concerning the sizing of electric drives for industrial applications. In addition, the operating characteristics of dc and ac electrical drives are verified by experimental tests carried out in laboratory. Finally, some computer models of the most common electric drives are used and explained.

Office hours

See the website of Luca Zarri

See the website of Fiorenzo Filippetti