17387 - Electrical Drives

Learning outcomes

The aim of this course is to present the steady-state characteristics of the modern electrical drives. DC and AC electrical drives will be analyzed and compared in order to emphasize which drive is more suitable for the most important industrial applications.

Course contents

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 MOTOR DRIVES

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.

 

VARIABLE FREQUENCY 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.

 

VARIABLE FREQUENCY 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

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.

Copy of the slides used for lecturing.

Teaching methods

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.

Assessment methods

Discussion of theoretical topics and presentation of the report of one experimental test. .

Teaching tools

Several test benches equipped with DC and AC drives are available in the laboratories for experimental tests.

Office hours

See the website of Domenico Casadei