Courses

Selected Topics of Electrical Machines

General

Course Contents

Theoretical part:
· Mathematical Models of 3-phase Electric Machines (Inductive and Modern),
· Per Unit System,
· Simple Electrical Equivalent Circuits, Control and Limitations during Operation,
· Operation in Transitional and Steady State in a two-axis system, V / f Control),
· Formulation of square pulses in voltage inverters (PWM inverters), Advantages of Vector Control (Response and Strength of Control; per Ampere (MTPA), Speed Range Expansion ·Flux or Field Weakening,
· Electric Power Converters, 3-phase Inverters, Sinusoidal PWM (Simulink Model of Inverter), Production of 3-phase power supply, Harmonic analysis
of the supply-driving voltage, effects on the generated electric torque.
· Analysis of the behavior of electric motors in different fault conditions,
· Advanced control of operating conditions for fault diagnosis, signal processing, variable measurements,
· Procedure for determination and fault estimation (current signal analysis, development of appropriate models, observers of variables, etc.),
Tasks – Practice Exercises:
· One Phase Error Analysis, Short-circuit of the winding part (Matlab / Simulink),
· Error Analysis of the Magnetic Field of the Rotor (Matlab / Simulink),
· Simulation of the Electric Motor Fault (Matlab / Simulink),
· Development of Error Observers (Matlab / Simulink).

Educational Goals

The aim of the course is to provide the student with the necessary knowledge regarding the principles of conventional operation of AC electric machines and their control considering the existence of errors.
Knowledge:
– Understanding the design, operation and control methods of electric motors through the development of electric motor models in fixed and rotating reference systems.
– Understand the use of observers and analysis of current signals in order to detect and diagnose operating errors.
Skills:
– Acquisition of design and calculation of simple electrical and mechanical equivalent mathematical models of electric motors.
– Acquisition of fluency in the design of observers-indicators of the operating conditions of the electric motor.
– Acquisition of skills in the analysis of the structure of simple observers.
– Methodical analysis and presentation of errors and the influence they have on the performance of the machine (eg torque fluctuations, additional harmonic stator currents, etc.) through simulation results.
– Analysis, design and implementation of advanced methods for error detection and diagnosis in AC electric motors.

General Skills

Research, analysis and synthesis of data and information, using corresponding technologies, Adaptation to new situations, Independent work, Teamwork – distribution of responsibilities, Intellectual competences.

Teaching Methods

Lectures, Exercises, Online guidance, Projected Presentations, E-mail communication, Online Synchronous and Asynchronous Teaching Platform (moodle).

Students Evaluation

Assessment Language: English / Greek
The final grade of the course is formed 100% by the grade of the theoretical part and the intermediate examination or project.
1. The written final examination of the theoretical part may include:
Solving of application problems, short answer questions, comparative evaluation of the theory elements etc.
2. The continuous evaluation of the theoretical knowledge that were acquired in the course by the method of project including the fault modelling of a 3-phase electrical machine.

Recommended Bibliography

1. Analysis of electric machinery and drive systems, Paul Krause, Oleg Wasynczuk, Scott Sudhoff, Steven Pekarek: 3rd Edition, © 2013, IEEE.
2. Electrical Machine Drives Control: An Introduction, Juha Pyrhönen, Valéria Hrabovcová, R. Scott Semken, ©2016, John Willey & Sons Ltd.
3. Electric Motors and Drives: Fundamentals, Types and Applications, Austin Hughes, 3rd Edition, ©2006, Austin Hughes. Published by Elsevier Ltd.
4. Motor Handbook, Fang Qi, Daniel Scharfenstein, Claude Weiss (Institute for Power Electronics and Electrical Drives, RWTH Aachen University), Clemens Müller, Ulrich Schwarzer (Infineon Technologies AG), Version 2.1, © 2019, infineon, iSEA, RWTH Aachen University.