33975 - Electrical Drives M

Course Unit Page

  • Teacher Giovanni Serra

  • Credits 6

  • SSD ING-IND/32

  • Teaching Mode Traditional lectures

  • Language Italian

  • Course Timetable from Sep 19, 2018 to Dec 17, 2018

Academic Year 2018/2019

Learning outcomes

The student addresses the key issues relating to the use of electrical variable speed drives in machine tools and automatic machines.
He studies DC and AC electrical drives, in order to understand their operating characteristics in reference to the various types of applications.

Course contents


Generalities about electric machines and drives. Power losses and heat transfer. Semiconductor power switches.

Electric energy conversion systems

AC-DC and DC-DC conversion: single-phase and three-phase diode bridge rectifier, single-phase and three-phase thyristor bridge rectifier, double three-phase thyristor bridge rectifier, chopper, PWM technique, full bridge converter.

DC-AC conversion: single-phase and three-phase voltage source inverter (VSI), square wave modulation, PWM technique.

D.C. drives.

D.C. machines: structure, operating principles, commutation, armature reaction, commutation poles, compensating windings, independent and series connected field windings, machine equations, torque characteristic, speed control.

A.C. drives
Asynchronous machine : structure, rotating field, slip, equivalent circuit, torque characteristic, speed control, constant V/F operating conditions, constant power operating conditions.
Synchronous machine : salient-rotor and cylindrical rotor machines, brushless machine with trapezoidal emf, brushless machine with sinusoidal emf, speed control.

Stepping motor drives.

Stepping motor: reluctance motor, permanent magnet motor, hybrid motor and linear motor.


Solenoid electromagnets

Typologies of electromagnetic actuators of solenoid types. Electromechanical characteristics. Electric time constant.


1.    L.Olivieri, E.Ravelli: ”Principi e Applicazioni di Elettrotecnica”, vol.2, CEDAM Editrice.

2.    N.Mohan, T.Undeland, W.Robbins: ”Elettronica di Potenza, Convertitori e Applicazioni”, Hoeply, Milano.

3.    B. Brunelli: “Conversione elettrica ed elettromeccanica dell'energia”, Pitagora, Bologna.

4.    A. E. Fitzgerald, C. Kingsley, A. Kusko: “Macchine Elettriche”, Franco Angeli.


PDF files of the PowerPoint presentation are also available.

Teaching methods

The course includes hours of lesson and hours of exercise where application examples are presented.

The proposed exercises need the use of  poket calculator together with tables and graphs from commercial data.

Assessment methods

Final oral examination.

Teaching tools

Blackboard, overhead projectors and PC based presentations are employed during lessons.

Simulation software and running models of electrical machines are also available

Office hours

See the website of Giovanni Serra