Download Snímka 1

Boboń Andrzej, Kudła Jerzy, Miksiewicz Roman
Silesian University of Technology, Gliwice, Poland
E-LEARNING BASED TEACHING
OF ALTERNATING CURRENT
ELECTRICAL MACHINES
ICEE‘2005, Gliwice, Poland
Presented module AC Electrical Machines is one of twenty-two
modules from the field of electrical engineering which have
been developed in the INETELE project realised in the
framework of the EU Leonardo da Vinci program.
project No CZ/02/B/F/PP/134009
Structure of the module:

Main
screen 1
Subscreen
Main
screen n
Subscreen
Main
screen 1
Subscreen
Main
screen n
Subscreen
Glossary
Symbols
Index
Contents

Title
screen
Induction Machines

Each module consists of main screens,
subscreens and screens containing the
table of contents, list of denotations and
their description as well as list of entries
and index.
It was assumed that the main screen
contains animations and the most
important formulas, diagrams, figures
and plots connected with the problem
discussed.
The subscreens comprise the detailed
description of the problem under
consideration, that is: necessary
explanations and derivations, as well as
questions and exercise problems aiding
the learning process.
The main screens can be used for
lectures whereas the subscreens can be
used for self-learning.
Synchronous Machines

ICEE‘2005, Gliwice, Poland
Purpose of the module
“AC - Electrical Machines”





The module is intended for students of universities of
technology, specialization electrical engineering with
Electrical Machines.
The module can also be used by academic teachers who
lecture on the theory of electrical machines and by
graduates who want to brush up and extend the
knowledge from the Theory of Electrical Machines.
The module under consideration is an extension of the
module Basic Principles of Electrical Machines developed
in the framework of the Inetele project
Macromedia Flash program is used for developing the
screens
Mathcad is used for simulations; its worksheets are
included in some subscreens
ICEE‘2005, Gliwice, Poland
Properties of the module

It was assumed that the electrical machine is a
dynamic system, properties of which in steady and
transient states can be determined basing on the
analysis of solutions of the equations being the
machine mathematical model.

the important part of the module includes the
problems connected with formulating mathematical
models of asynchronous and synchronous machines,
methods for solving the equations being these
models and physical interpretation of the results of
the solutions.
The module was worked out in the form possible for
presentation on web-sites with the use of interactive
and animated in Flash technique elements.

ICEE‘2005, Gliwice, Poland
The aim of animation and
interactive graphics
 to present constructions of electrical
machines,
 explain the principles for formulating their
mathematical models,
 present and interpret physically the
solutions of the machine equations in
steady and transient states,
 learn and analyse the machine properties
basing on the equivalent diagrams, vector
diagrams and characteristics in steady
states as well as waveforms in transients.
ICEE‘2005, Gliwice, Poland
Layout of the AC Machines Module Contents
AC machine constructions
Mathematical models in phase coordinates
Steady state
Equations, equivalent circuits,
vector diagrams
Analytical relations describing
machine properties
Machine characteristics
Transient state
Two-axis transormations
Machine equations and equivalent
circuits in dynamic states
Analytical and numerical solutions
Dynamic waveforms
ICEE‘2005, Gliwice, Poland
Exemplary main screens of an induction machine
1. Construction of an induction machine
The screen presenting the most important elements of the induction machine construction.
When one brings mouse cursor on any machine element, its name appears.
ICEE‘2005, Gliwice, Poland
Exemplary main screens of an induction machine
2. Voltage equations of three-phase squirrel-cage induction motor
 The way for formulating the differential equations and denotation of the quantities in
them are explained in animations activated by a mouse when pressing the key PLAY.
 The animation consists in showing “step by step” the elements of the differential
equation for one phase of the stator or one “mesh” of the rotor cage.
 The element corresponding to the shown equation element (circuit voltage, voltage
drop along resistances, induced voltages) is simultaneously marked on the electrical
diagram.
ICEE‘2005, Gliwice, Poland
Exemplary main screens of an induction machine
3. Power balance of a three-phase wound-rotor induction motor
• The successive stages
of animation show
particular active powers
in the machine both on
the motor model and its
equivalent diagram.
• The flow of active power illustrates the way of conversion of the electric active
power supplied from the network by the stator windings into the mechanical power.
• The presentation of the active power on the equivalent diagram enables
determining the relationships that define the components of the power balance
expressed by means of the stator and rotor currents and the equivalent diagram
parameters.
• The final stage of the power balance is determination of the relation for the machine
electromagnetic torque.
ICEE‘2005, Gliwice, Poland
Exemplary secondary screen of
an induction machine
Simulation experiment in Mathcad program
• The programs prepared in Mathcad are activated by means of appropriate links.
• They allow conducting by one-self simulation experiments for different operating
conditions, ratings and parameters of electrical machines.
• The screen shows exemplary the code fragments and computation results
of the induction motor static characteristics for different RMS value and frequency
of the stator voltage.
ICEE‘2005, Gliwice, Poland
Exemplary main screens of a synchronous machine
1. Steady state equivalent diagram and phasor diagram
• The screen presents the equivalent circuit of a salient-pole synchronous generator
working alone, loaded with an impedance.
• For the selected type of the load impedance (R, L, RL, RC) the exemplary vector
diagram of the generator is shown.
• The user, after choosing in the interactive mode the type of a synchronous machine
and the kind of the load, sees step by step the way of constructing the generator
vector diagram by means of animations.
ICEE‘2005, Gliwice, Poland
Exemplary main screens of a synchronous machine
2. Synchronisation of a synchronous machine with the infinite bus-bar system
•The user selects the kind of a synchroniser, sets the values of the field current and
the speed of the machine rotor.
• Animations show rotation of the vector diagrams of the generator and infinite bus-bar
system voltages and changes of the bulb voltages, which cause their successive
switching on and off.
• The lamps show whether the conditions for synchronisation of the generator with the
infinite bus-bar system are met.
ICEE‘2005, Gliwice, Poland
Exemplary main screens of a synchronous machine
3. Steady state characteristics
• The user selects the active power loading the generator and activates the animation
during which the V-curve for the chosen power is drawn point by point.
• Simultaneously, the machine vector diagram changes appropriately.
ICEE‘2005, Gliwice, Poland
CONCLUDING REMARKS
 The module “AC Electrical Machines” developed in the framework of the
Inetele program aids giving lectures enabling presentation and explanation
of difficult problems from the theory of electrical machines by means of
interactive actions and animations in the main screens.
 The lectures become more attractive and easier to understand.
 The detailed explanations for the problems presented in the main screens
are in the subscreens.
 They, together with the derivations and questions, make selfunderstanding of the problems easier.
 The programs in Mathcad environment included in the module allow
carrying out simulation experiments for different ratings and parameters of
electrical machines by one-self.
 The module developed can be used for self-learning of the theory of
AC Electrical Machines aiding the books on this subject.
ICEE‘2005, Gliwice, Poland