Learning objectives
The course aims at providing basic knowledge pertaining the operation and use of the different types of electric motor drives:
* direct current machines;
* DC and AC brushless;
* asynchronous machines;
* step motor drives.
At the end of the course the students should know, for each type of motor drives:
* construction details;
* operating principles;
* the applicable sensors for current, position and speed sensing;
* the main control schemes and algorithms;
* the possible applications (industrial, powertrain, appliances, etc.).
Prerequisites
Electric circuits; automatic control; basic physics.
Course unit content
Electromechanical energy conversion; DC, AC (brushless, induction) and stepping motor drives.
Full programme
1. Introduction to electric drives, electromechanical energy conversion, common features, operating zones, energy, coenergy, torque calculation. Introduction to polyphase electrical machines, distinction between anisotropy torque and permanent magnet torque. (8 hours).
2. Direct current machine, construction and operating principle. Quadrants of operation, flux weakening. Dynamic model, feedback control of current and speed. Switching power supply through PWM-controlled H-bridge, current ripple, current circulation, freewheeling diodes, braking resistor. (10 hours).
3. DC brushless machine, pole pairs, cogging torque and skewing. Two-phase-on and three-phase-on operation, DC brushless torque calculation. Power supply through three-phase bridge. Control through on/off Hall effect sensors. (6 hours).
4. Current sensors: shunt resistor, uncompensated and compensated Hall effect sensor. Position and speed sensors: tachometric dynamo, absolute and incremental encoder, resolver. (2 hours).
5. AC brushless machine, generation of rotating magnetic field, torque angle, Clarke's and Park's transformations, model of the machine on rotating axes. AC brushless torque calculation, anysotropic machines, flux weakening, vector control and MTPA/MTPV trajectories. (7 hours).
6. Induction machine, slip, circuit model. Induction machine Induction machine torque calculation, torque/speed curve, off-grid operation and starting techniques. Constant V/f control and slip control through inverter. Introduction to vector control. Induction machine tests. (7 hours).
7. Incremental motion drives, variable reluctance, permanent magnet and hybrid types. Open-loop control, microstepping, switched reluctance machines (2 hours).
8. Comparison of rotating electrical machine types: properties and typical operating fields, automation (axis and spindle drives), powertrain. (1 hour).
Bibliography
Lecture notes available on the Elly online platform.
Teaching methods
The course will mainly consist of traditional lectures, with a limited amount of computer simulation.
