Electrical Engineering

FABIO GIULII CAPPONI

The course aims to guide the student in the understanding of the principles of operation of an
electric drive and its components. The course will also provide the means to analyze the behaviour of
an electric drive both in steady state and during transients. The course is completed by design
fundamentals.

1. Knowledge and understanding
By the end of the course, students will have acquired advanced knowledge and understanding of:
• General concepts and mechanical couplings: The structure of electrical drives within industrial processes, the study of mechanical couplings, and feedback transducers (current, speed/position sensors such as resolvers and encoders).
• DC Drives: Operating principles, steady-state characteristics, dynamic modeling, full-bridge switching converter applications, current, speed, and position control loops, and field weakening strategies.
• Brushless and PMSM Drives: Classification and mathematical models of Brushless DC and Brushless AC drives (PMSM/IPM), reference frame transformations (arbitrary reference systems and rotating vectors), torque control schemes (e.g., MTPA), and field weakening.
• Induction Motor Drives: Dynamic modeling of induction machines, scalar control techniques (constant V/f open/closed loop, slip control), and direct/indirect vector control (steady-state and transient analysis) with related controller schemes and flux observers.
• Digital Control Processors: Hardware architecture of modern digital processors for drives (microprocessors, microcontrollers, DSP) and real-time control software implementations, including speed and flux observers.
2. Applying knowledge and understanding
Students will be able to apply their engineering knowledge to:
• Transient and steady-state analysis: Analyze, analytically and through numerical/laboratory exercises, the static and dynamic behavior of electrical drives during electromechanical transients (such as speed transients in DC machines or d-q dynamic behavior in AC machines).
• Control loop synthesis: Design, tune, and optimize cascaded control loops (current, speed, and position loops) by integrating concepts from Power Electronics and Automatic Control.
• Hardware/Software implementation: Adapt and translate theoretical control algorithms (scalar and vector control) into concrete real-time control software structures running on microcontrollers or DSPs.
3. Making judgements
Through modeling analysis and lab experience, students will develop the ability to:
• Critical technology selection: Evaluate and select the most suitable drive type (DC, Brushless DC/AC, induction motor) based on specific industrial application requirements and load characteristics.
• Control strategy optimization: Choose and technically support the choice of a specific control layout (e.g., scalar vs. direct/indirect vector control, field weakening, or MTPA) considering dynamic performance, cost, and sensor availability (e.g., using flux/speed observers).
4. Communication skills
In alignment with the oral examination requirements, students will be able to:
• Logical and rigorous presentation: Structure and deliver a technical speech clearly and logically, describing mathematical formulations and control block diagrams of complex electrical drives.
• Technical terminology and defense: Use precise engineering terminology from the electrical, power electronics, and control systems fields, demonstrating the capability to technically discuss and support their statements.
5. Learning skills
The course equips students with the methodological skills to:
• Autonomous technical reading: Study and comprehend textbooks, international scientific publications, reference handbooks, and datasheets on advanced electric drives and DSP applications.
• Interdisciplinary integration: Independently synthesize and apply cross-disciplinary concepts derived from their prerequisites (Electrical Machines, Power Electronics, and Automatic Control) to keep up with the technical evolution of modern electrical drives.

Contents of the Electrical Machines subject are required, together with the ones acquired in the Power Electronics and Automatic Controls subjects.

1. General introduction on electrical drives (1 credit)
Electrical drives in industrial process
Study of mechanical couplings
Transducers

2. DC Drives (3 credits)
The operating principle of d.c. machines
Mechanical and electrical characteristics
Dynamic Model
Analysis of the speed transient
d.c. drives with switching converters (full-bridge converter)
Current control for d.c. drives
Speed control
Position control
Flux weakening for d.c. drives

3. Brushless Drives and Permanent Magnet Synchronous Motors (PMSM) (2 credits)
Classification
Brushless dc drives: mathematical model
Brushless dc drives: drive system
Brushless dc drives: control schemes
Coordinate transformations. arbitrary reference system
Coordinate transformations. the rotating vector
Brushless ac drives: mathematical model
Brushless ac drives: control schemes
Brushless ac drives: constant power speed range (field weakening)

4. Induction motor drives (3 credits)
Scalar control: constant V / f control (open loop and closed loop)
Scalar control: slip control
Dynamic model of asynchronous machine
Direct and indirect vector control: steady state analysis
Vector control: transient analysis
Vector control: schemes for indirect controllers
Vector control: schemes for direct controllers

5. Digital processing in electric drives (1 credit)
Microprocessors, microcontrollers and DSP
Examples of software for real-time control of electric drives
Numerical and lab exercises

Lecture notes (to be taken by the students)

1. R. M. Crowder - “ELECTRIC DRIVES AND THEIR CONTROLS” - Ed. Oxford Science Publications
2. W. Leonhard - “CONTROL OF ELECTRICAL DRIVES” - Ed. Springer-Verlag
3. P. C. Krause, O. Wasynczuk, S. D. Sudhoff - “ANALYSYS OF ELECTRIC MACHINERY” - Ed. IEEE Press
4. P. Pillay et alii - “PERFORMANCE AND DESIGN OF PERMANENT MAGNET AC MOTOR DRIVES” - IEEE Industry Applications Society Tutorial Course, 1991
5. R. Valentine - “MOTOR CONTROL ELECTRONICS HANDBOOK” - Ed. McGraw-Hill
6. D. W. Novotny, T. A. Lipo - “VECTOR CONTROL AND DYNAMICS OF AC DRIVES” - Ed. Oxford Science Publications
7. T. Kenjo, A. Sugawara - “STEPPING MOTORS AND THEIR MICROPROCESSOR CONTROLS” - Ed. Oxford Science Publications
8. T. A. Lipo et alii - “SYNCHRONOUS RELUCTANCE MOTORS AND DRIVES - A NEW ALTERNATIVE” - IEEE Industry Applications Society Tutorial Course, 1992

Classes are mainly based on traditional, frontal teaching. Numerical and lab exercises are also held, in order to verify the capability of students to apply the knowledge acquired during classes.

Not mandatory, but highly recommended

The evaluation will be made through an oral colloquium, during which the student will demonstrate:
- his knowledge of the topics of the subject,
- his ability to present his speech in a logical and rigorous form, using appropriate terminology,
- his capability to technically discuss and support his statements.

Current Transducers
Resolver
Speed Observer
Speed Transient Analysis in a DC Machine
Current Loop Synthesis
Velocity Loop Synthesis
Arbitrary Reference Frame
Dynamic Steady-State Model of a Permanent Magnet Synchronous Machine
MTPA
Block Diagram of Torque Control for an IPM Machine
Steady-State Analysis of Vector Control for an Asynchronous Machine
Direct Vector Control
Flux Observer

• Transducers (week 1 and 2)
  • Books: Lecture notes


• DC motor drives (week 3, 4, 5 and 6)
  • Books: Lecture notes


• Arbitrary reference frame (week 7 and 8)
  • Books: Lecture notes


• PMSM drives (week 9 and 10)
  • Books: Lecture notes


• Induction motor drives (week 11 and 12)
  • Books: Lecture notes


• Numerical and practical labs (week 13)
  • Books: -