CFU: 9
Prerequisites
Basic knowledge of magnetostatics, electrical circuits and three-phase systems; basic knowledge of the techniques required for solving electrical circuits in sinusoidal/distorted steady state with the phasor domain approach and the decomposition of the forcing inputs in their harmonic components; basic knowledge of the decomposition techniques of three-phase variables into common mode, direct, inverse and differential components; basic knowledge of semiconductor devices (diodes, mosfet, IGBT,…).
Preliminary Courses
Fondamenti di circuiti (Fundamentals of circuits).
Learning Goals
The aim course aim is to provide the student with the elements necessary for understanding the architectures of electrical drives both at a low level (by providing the knowledge that allows the student to discern the drive components by understanding their operating principle) and at a high level (by providing the knowledge that allows the student to become familiar with the control strategy of the whole system).
Expected Learning Outcomes
Knowledge and understanding
The teaching is aimed at providing the necessary knowledge to understand the different configurations of electric drives and at the same time address the problems associated with the relative control. Following the introduction of static and rotating electrical machines, the architectures of the semiconductor power converters will be defined, highlighting how the control of the system must be conditioned by the conversion architecture. The student must demonstrate that he has understood the operating principle of electric machines, also managing to underline the characterizing differences between the different types, relating them at the same time to the corresponding strengths. The student will also have to demonstrate that he has understood the operation of semiconductor converters, also managing to highlight the fields of application and relevant problems for each type.
Applying knowledge and understanding
The student must demonstrate that he is able to establish the power law of an electric machine based on the regulation constraints. At the same time, the student must be able to choose a suitable conversion structure to ensure a variable power supply to the electrical machine. Finally, the student must demonstrate the ability to configure an electric drive and appropriately characterize its control.
Course Content - Syllabus
- Introduction to the electrical machines
- Components of the electrical machines
- Elementary magnetic circuits
- The electric transformer
- Mathematical model
- Properties of a single-phase transformer
- Rated data
- Voltage drop
- Efficiency
- Parallel connection of two single-phase transformers
- The three-phase transformer
- Windings connection
- Vector group
- Star displacement in the three-phase transformers
- The induction machine
- Architecture of a radial rotating electric machine
- Flux density distribution
- Linked windings fluxes
- Mathematical model
- Electromagnetic torque expression
- Speed/torque relationship in steady state
- Speed regulation
- The synchronous machine
- Architecture of a salient poles synchronous machine
- Flux density distribution
- Linked windings fluxes
- Mathematical model
- Electromagnetic torque expression
- Interaction torque
- Reluctance torque
- Load angle
- Stability
- Speed regulation
- Permanent magnets synchronous machines
- The DC machine
- Mathematical model
- Speed regulation
- The power electronic converters
- The modulation time
- Behaviour of the semiconductor devices in the power electronics converter
- AC/DC converters
- DC/DC converters
- DC/AC converter
- The voltage source three-phase inverter (VSI)
- Carrier based modulation of the VSI
Readings/Bibliography
A. Fitzgerald e C. Kingsley, Electric Machinery, McGraw-Hill, 2002
N. Mohan, Power Electronics, John Wiley & Sons Inc, 2002
Teaching Methods
The teacher will use: a) frontal lessons for about 90% of the total hours, b) laboratory exercises for about 10% of the total hours.
Examination/Evaluation criteria
Exam type
Written and oral. Questions of the written exam refer to: numerical exercises.
The written test is aimed at verifying the student's ability to apply the knowledge acquired in order to solve simple problems relating to the different aspects of the regulation of electric drives both relative to the electric machine (regulation law) and to the converter (modulation law).
Evaluation pattern
The positive outcome of the written test is not required for accessing the oral test. The written test contributes 20% to the final evaluation.