- Email: [email protected]
Development of a Modern Electric Drives Course
Copyright @ IFAC Automatic Systems for Building the Infrastructure in Developing Countries, Ohrid, Republic of Macedonia, 2001
DEVELOPMENT OF MODERN ELECTRIC DRIVES COURSE Slobodan Mircevski 1, Marco Rival, Zdravko Andonov 1
IFaculty of Electric Engineering - Skopje, Karpos Il b.b. 91000 Skopje, Republic of Macedonia, [email protected] .edu.mk, [email protected] 2
Un iversita degli studi di Milano, Dipartimento di fisica-Sezione Elettronica, 20133 Milano,Via Celoria 16, [email protected] .it
Abstract: In the Faculty of Electric Engineering (FEE) Skopje, University "Sts. Cyril and Methodius" Republic of Macedonia the course "ModeIing of electric drives" on post graduate studies is established, in the frame of the TEMPUS-PHARE JEP "Development of Power Electronics Courses" using a modem approach to teaching electric drives. Copyright @20011FAC
Key words : electric drives, postgraduate studies, power electronics
1.
This situation express a conflict of interests between student and industrial needs. Students mean that in the traditional disciplines there are no large development and implementation for modem technologies and there are no lot of chances for the good employment.
INTRODUCTION
1.1 Crisis in traditional courses of Electrical Power Engineering directions at FEE - Skopje At the Faculty of Electrical Engineering - Skopje exist, at the moment. four different direction: Power Engineering; Power Conversion and Automation and Power Engineering; Electronics and Telecommunications and Computer Technique, Information and Automatics.
DPE .PCA
Two of them deals with the Electrical Power Engineering: Power Engineering (PE) and Power Conversion and Automation (PCA). Because of fast of electronics (specially development microelectronics), information technologies, and communications and their influence in modem life , the student interest is focalized in these new argument and the more traditional directions are not attractive compared with the two other directions . In Fig. I is shown first year students interest for all directions in last two school yt:ars at the Faculty of Electrical Engineering - Skopje .
[JET [JCTIA
97/98
98/99
99/00
Fig. I Student interest for directions at FEE - Skopje From the other s ide, the industry needs well prepared engineers in all electrical engineering branches, who are familiar with new technologies implemented also in power electrical engineering.
253
If industry requires well-prepared engineers in this field, it is responsibility of universities to fulfill this need. Coupled with employment opportunities and the infusion of power electronics and controls, the traditional subjects became more attractive and both industries and students could benefit. f The electrical drives course it is only one example of how it was possible join traditional subject as Electrical Motor Theory and newer microelectronic-controlled power supply in high performance motor control to turn the crisis in traditional power engineering courses into an opportunity.
The participants from the EU side are: University of Surrey - UK (prof. David Hamill and prof. Keith Bateson), Universidad Politechnica de Madrid Spain (prof. Javier Uceda, prof. Jose Cobos and prof. Fernando Briz) and Universita Degli Studi di Milano - Italy (prof. Piero Maranesi and prof. Marco Riva) . Every foreign professor has an alternative with professor from Faculty of Electrical Engineering Skopje, Macedonia (prof. Tomislav Dzekov, prof. Ljupco Panovski, prof. Goce Arsov, assistant Goce Sutinovski, prof. Ljupco Karadzinov, prof. Metodija Kamilovski and prof. Slobodan Mircevski). From the macedonian side also participate enterprises: Rade Koncar -Foreign Trade and EMO - Automation & Electronics and Macedonian National TEMPUS Office.
I. 2 Importance a/electric drives
The electric drives are the greatest consumers of the total produced electric energy and their automation is the base for higher quantity and quality of production. In the US electric motors consume about 65% of the total electric energy production. It is clear that electric drives are the important criterion for industrial and technology development of a country . So, the electric drives need corresponding attention at education in electric engineering.
2.2 Undergraduate courses In the first year of the project the undergraduate studies existing courses in power electronics were reviewed and the four new subjects were introduced . I. 2. 3. 4.
A electric drives is a system which combines work machine with electri c motors. power electronics and controls. However the main aim is to control speed and position of mechanical loads. The need for electric drives is obvious to anyone civilized person . There has been a quite evolution underway in the process - control industry where hydraulic drives are being replaced by electric drives. Robotics and factory automation have become vital for the industrial competill\ <:ness in the global market of today. Electric transportation, including electric vehicles such as automobiles and buses, requires electric drives . The cost of wasted energy and environmental pollution are increasingly important concerns. Energy savings and flexibility by using power electronics is proved in industrial drives practice. These applications combined represent a huge market need.
2.
Power semiconductor devices Generic power electronic circuits High frequency and resonant converters Practical converter design considerations.
Also subjects are in the last (fifth) year of studies as optional. Because of different background in electronics and different power electronics needs in different directions the first two courses are optional for the student at PE, PCA and ET. The last two are only for the student at ET direction .
2.3 Postgraduate courses In the academic 1999/2000, the postgraduate courses were established, at a new postgraduate direction Power Electronics. The student interest were very good (20 students) and there were students who have graduated at all existing branches at Faculty of Electrical Engineering - Skopje. The students distribution depend on direction is shown in Fig. 2.
THEMPUS - PHARE JEP "DEVELOPMENT OF POWER ELECTRONICS COURSES" CTIA 5%
2. 1 Project outline The aim of the THEMPUS - PHARE J EP-121 03-97 "Development of power electronics courses" (1998200 I) is to satisfy the need of Macedonian industry for the adequately educated electrical engineers who can manage with the practical problems in industrial plants. In the project the existing courses in power electronics and related areas have to be reviewed and the new subjects at the undergraduate and postgraduate studies have to be developed.
PE 20%
PCA 15% 60%
Fig. 2 Students distribution depend on direction There are eight subject in this level:
254
I. 2. 3. 4. 5. 6. 7. 8.
Intelligent systems in power electronics. Introduction: Expert Systems; Fuzzy Logic; Neural Networks , Evolutionary Programming. Design for Compliance with Standards. Introduction to Electromagnetic Compatibility (EMC); Basic Electromagnetic Principles; EMC Requirements for of Electronic Systems; Nonideal Behavior Components; Radiated Noise and Susceptibility; Conducted Noise; Grounding; Shielding; EMI in Switched Mode Power Supplies; Intrinsic Noise Sources.
Simulations in Power Electronics PWM Techniques in Power Electronics Power Electronics Components and Integration Power Electronics Applications Modeling of Electric Drives Microprocessors and Digital ICs for Control in Power Electronics Intelligent Systems in Power Electronics Design for Compliance with Standards
The students choose seven subjects and after passing them they have to do their MSc. thesis to finish their studies.
2.5 Laboratory equipment 2." Subject ~y/labuses
The realization of the developed subjects was in tight connection with practical measurements and training. For this purposes in the last two years about 50000 US$ were spent for the student laboratory equipment. The most of equipment was bought from the German firm "WUEKRO electronics" .
The main topics of each postgraduate subject are : Simulations in power electronics. Introduction ; Simulation in Design Process; Frequency Domain versus Time Domain Analysis; Challenges in Simulation ; Classification of Simulation Tools and Historical Overview: Issues in Numerical Solutions; Overview of some Widely Used Simulation Programs; Overview of Simulator Capabilities by Examples; Power Semiconductor Device Models for Circuit Simulation: Conclusion.
The laboratory equipment is suitable both for training purposes, so as investigation works in MSc thesis . From the aspect of the purposes the main equipment can be divide in the two segments: general power electronic components and electric drive . General power electronic components. As an elements for general power electronic circuit were bought: Power electronics components, Rectifier circ uits, DC chopper and AC Power Controller with accessories and motors.
PWM Techniques in Power Electronics. Introduction ; DC to AC Power Conversion; Introduction to Space Vectors: Perform ance Criteria; Open Loop Schemes; Closed Loop Schemes; Multilevel Converters; Current Source Converters.
Electric drives modules. The electric drives modules are consist of: Braking module with : DC shunt machine, Eddy-current brakes and dynamometer with control units ; AC drives test unit with : Three phase squirrel-cage induction motor; Simovert 6SE70 and M icromaster frequency converters and DC drives test with : DC shunt machine; Simoreg K converter; controller with P, I and D variable components; Setpoint potentiometer; Control deviation units (for speed and current loops) with accessories .
Power Electronics Components and Integration. Practical Energy storage Elements; Magnetic Components Design; Advanced Power Semiconductor Devices and Circuits; Hybrid Power Electronics Circuit ~. Power electronics application. Introduction; Switching DC Power Supplies; Power Conditioners and Uninterruptible Power Supplies; Motor Drive Applications; Residential and Industrial Applications; Electric Utility Applications; Optimizing the Utility Interface with Power Electronic System.
3.
Modeling of electric drives and machines. This subject will be present in details in the next heading.
COURSE "MODELLING OF ELECTRIC DRIVES"
3.1 Course outline
Microprocessors and Digital ICs for Control in Power Electronics. Introduction; Microcomputer of Power Electronics Systems ; Control Microcomputers basics: Real-Time Using Microcomputers; Microcontrollers; Advanced M icroprocessors for Control of Power Electronics Systems; ASIC for Control of Power Electronics Systems; Design of Microprocessor-Based Control Systems; Development Tools; Application Examples.
In the undergraduate studies the courses of electric machines and electric drives exist only in PE and PCA directions . The students from the other directions have no any exam in this area. The students from ET direction, at the moment, have no any course in control techniques area in under graduate studies. Because of that the postgraduate course "Modeling of electric drives" should cover
255
electric machines, power electronics and controls on an "as-needed" basis. The course had to be based on space-vector theory approach and tools for modem control - state space, digital, adaptive, robust and intelligent control systems. In view of societal needs, the main goal was to develop a course which will interest a large segment of the electric engineering postgraduates (16 students). It should also be of interest to other students from mechanical and civil engineering disciplines where electric drives are used for applications in process control, robotics and transportation (Riva M., 2000).
motors ; The different control schemes for AC supplied DC adjustable drives and schemes for DC to DC adjustable drives are explained. Synchronous Machine Vector Control (3 lectures). This section covers: The advantages of AC vs . DC drives ; Advantages and disadvantages of synchronous vs . induction machines; The voltage and current source inverters with the basic control topologies ; The basic principles of vector control strategy, dynamics of synchronous machine in vector control with its implementation in drives; The brushless AC motors, their mode ling, field oriented and basic control schemes.
32 Course Syllabll.1 Induction Machine Vector Control (4 lectures). The basics of induction machine vector control ; Implementation of direct and indirect field orientation, dynamics of FO induction machine and torque control requirements ; The different control strategies (current regulated CSI and PWM inverters, hysteresis regulator, ramp comparison controller, stationary and synchronous frame regulators, feed forward and augmented feed forward compensation, predictive control); The small signal analysis with machine equivalent circuits, equations and stability analysis ; The induction motor control based on small signal model in this section are explained.
The course consist of 12 heading which give to students basic principles of electrical machines, working machines, control techniques and application of electric drives. The main topics are briefly described in the following sections. Space-vector Theory Approach (2 lectures). The knowledge of space vector theory is a basic for the electrical machine analysis. In this section the basic postulates of the theory is given. The equations of different electrical elements and their presentation in dynamic and quasi stationary regimes. The transformation of rotating quantities (e.g. rotor windings, current) and the relationship with the generalized electrical machine theory is presented.
Observers and Estimators (3 lectures). The different types of indirect and direct controllers for induction motors are introduced and their implementation are explained.
Induction Machine (3 lectures). The induction machines is the most used in electric drives . In this section basic concept of different types of induction machines and the function principles; Full and reduced order model of induction motor in space vector and reference frame theory: The basic induction motor regimes with circuits and equations (start up, steady state and braking); The operation with sinusoidal and non sinusoidal voltage supply with the emphasis on variable frequency power electronic supplies are presented.
of Working Speed-Torque Characteristic Mechanisms and Electric Motors (I lectures). In this section: The basic elements of electric drive ; Operation modes; Load torque and classification; Coupling of Working Mechanism with Electric Motors ; Dynamics of drive system and steady state stability are explained. Parameters Estimation (2 Synchronous Motor; Tests Determination of stator and constants and drive inertia are
Svnchronous Machine (3 lectures). This section covers following items: The basic principles of synchronous machine; Steady state and transient operation; Variable frequency synchronous machine; Naturally commutated synchronous motor drives; Permanent- magnet synchronous motor - principles model and control.
lectures). Tests for for Induction Motor; rotor parameters, time given.
DTC for Asynchronous motors (2 lectures). Direct Self Control Regulator; Speed regulator; Direct torque control; Advantage and Disadvantage of DSCDTC; Switching, Commutation; Predictive scheme; Sensorless applications; Open loop methods, MRAS ; Observers for DTC are explained.
DC Motors (2 lectures). The main usage of DC motors are in adjustable speed drives . Induction motors are more reliable and cheaper and in the last years with development of power electronics and control techniques DC motors are replaced by the induction motors. That why this section is shorter than previous. In this section: Basic construction and operating principles for the different types of DC
DTC for Synchronous motors (2 lectures). This section covers: DTC in Brushless applications; Flux and Torque estimators; Switch tables ; Sensorless application; Example of implementation ; Anisotropy machine.
256
Drives for Specific Applications (3 lectures). This section covers: Energy Saving Possibilities in High Power Drives: Cranes and Hoist Drives; Machine Tools: Steel Rollin g Mills ; Cement Mills: Sugar Mills: Textile Mills : Coal Mines drives.
IEEE video tutorials "The history of Power Converters in Motor Control" by W. McMurray and "Adjustable Speed Drives" edited by S.J. Salon was translated and titled in macedonian and they was presented to our students. We also used other video cassettes by different equipment vendors as: ABB, FLUKE, EMO, BAKER to give information to students in industry applications.
Laboratory training. Laboratory training course was organised in three part: I. ., 3.
Real equipment exercises: Simulation exercises and Video tutorial s.
Into consideration that the most of students were employed there was no need of industry visits or other kind of practice. For unemployed students visit to different industrial plants concerning application of electric drives could be arranged.
Real equipment exercises. This exercises had to be done using the existing equipment in laboratory for electric drives at Faculty of Electrical Engineering and the new bought for the lEP purposes.
In this moment the course "Mode ling of electric drives" to the student is present in the classical way with teaching lessons and exercises in the laboratory. Because the most of students are employed in the industry and don't live in Skopje there were problems for the students to be on lessons . Today with intern et resources developed in Macedonia and FEE the solution for this problems is implementation of the distance learning. Of course, distance learning is suitable for theoretical and simulation parts of the course, but its implementation will be useful for the students, which can not be on lessons and also for the all students when they will prepare the exam.
The existing equipment suitable for this course are : 2 DC converters for -l quadrant drive ; I Converter for 4 quadrant drive, realised as load imitator with DC motor; 2 analogue frequency-voltage converters for IM and I DTC frequency-voltage converter. The converters are equipped with their own measurement instruments and also have specially realised measuring points for oscilloscope. The specification of new acquired previous section of this paper.
IS
given in
The measurement equipment is a necessary, important and expensive part of a laboratory for electric drives. New instruments for measuring Voltage , current, frequency, resistance, inductance are acquired, in c luded analogue and digital oscilloscopes.
The good basics for this can be online course In electric drives developed at the Politecnico di Milano, Italy (http://corsi.metid.polimi.it) (Castelli Dezza F. at aI., 1997) and interactive CD which IS included with (Boldea I at al. 1998).
4.
Simulation exercises. The basic concept of simulation exercises is usage of most popular simulation packages. Because of existing course "Simulations in power electronics" in which are given basics in simulation, in course "Modeling of electric drives" are realized only Jl!dicated exercises which covers the most of course sections.
CONCLUSION
In the modem industry application electric drives are one of the most important parts. The modem drives includes knowledge of electric machines, power electronic and control systems and techniques. The classic electrical power engineering directions at Faculty of Electrical Engineering - Skopje, Republic . of Macedonia had problems with the students interest, because of fast development of computer sciences and telecommunications, made more attractive courses which involved information technologies and microelectronics.
The most of exercises were done using MatlabSimulink as the most popular and most suitable for control drive simulation (Castelli Dezza, at al.. 1997), and using Mathcad and PSpice (Mircevski and Andonov, 1998). Useful tools for the simulation exercises were IEEE self-study courses: Adjustable speed drives (Stessing and Celanese, 1998) and Modem Control Systems (Masten , 1995).
The aim of THEMPUS - PHARE lEP "Development of power electronics courses" is to improve the under and post graduate studies in segment of power electronics which application in most cases is electrical power engineering. It is really to expect that this project should turn the crisis in traditional power engineering courses into an opportunity.
Video tutorials. Membership in IEEE. Industry Application Societ; was a great positive experience. The basic ideas about video tutorials were obtained of IEEE Video Program .
257
The postgraduate course "Modeling of electric drives" was developed to help student to understand electric drives and their application. The course was designed for students with various background which means that there is no need of basic knowledge in electric drives. It has theoretical and practical sections. As a proof of the slIccessful course concept is the excellent student interest in the first year of postgraduate studies (80 %).
REFERENCES Boldea I, Boldea A. and Nasar S. A. , Electric drves, CD ROM interactive, CRC Press, USA, \998. Castelli Dezza F., E. Chiesa, A. Monti and M. Riva (\997) . Using a new interactive Matlab® Toolbox for Control Design and Teaching of Electrical Drives. EPE 97 Trondheim, Norway. VollI, pp. 1008-\0\3 . Leonhard W. (\998) . Electric energy in the information age - an indispensable commodity. 10th EDPE, Dubrovnik. Croatia. pp. 1-8. Masten M, K. (\995) . Modern Control Systems, Self study-course. IEEE, Piscataway, USA . M ircevski S. A. and Z. Andonov (\998). Modern laboratory trammg in electric drives . MELECON, Tel Aviv, Israel. pp. 155-\60. Mohan N., T. Underland, M. Riaz and V.D. Albertson (\996) . Teaching an introductory course on electric drives using space vectors, without the prerequisite of electric machine theory. PEMC 96. Budapest, Hungary. Vo!. 3, pp. 20-3\ . Moreira 1. C. , T . A. Lipo and V. Blasko, (199\). Simple Efficiency Maximizer for an Adjustable Frequency Induction Motor Drive. IEEE Trans. Industry Applications, vot. 27, No. 5, pp.940946. Novotny D. W. , T. A. Lipo (1996). Vector control and dynamics of AC dives , Clarendon press. Oxford, UK. Riva M. , (2000) . Hodelling of electric drives. JEP Development of Power Electronics Courses. Stessing W. and H. Celanese, (1998). Adjustable speed drives. Self-study course. IEEE, Piscataway, USA . Vas P. (\996). Electric machines and drives. Clarendon press, Oxford, UK.
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DEVELOPMENT OF MODERN ELECTRIC DRIVES COURSE Slobodan Mircevski 1, Marco Rival, Zdravko Andonov 1
IFaculty of Electric Engineering - Skopje, Karpos Il b.b. 91000 Skopje, Republic of Macedonia, [email protected] .edu.mk, [email protected] 2
Un iversita degli studi di Milano, Dipartimento di fisica-Sezione Elettronica, 20133 Milano,Via Celoria 16, [email protected] .it
Abstract: In the Faculty of Electric Engineering (FEE) Skopje, University "Sts. Cyril and Methodius" Republic of Macedonia the course "ModeIing of electric drives" on post graduate studies is established, in the frame of the TEMPUS-PHARE JEP "Development of Power Electronics Courses" using a modem approach to teaching electric drives. Copyright @20011FAC
Key words : electric drives, postgraduate studies, power electronics
1.
This situation express a conflict of interests between student and industrial needs. Students mean that in the traditional disciplines there are no large development and implementation for modem technologies and there are no lot of chances for the good employment.
INTRODUCTION
1.1 Crisis in traditional courses of Electrical Power Engineering directions at FEE - Skopje At the Faculty of Electrical Engineering - Skopje exist, at the moment. four different direction: Power Engineering; Power Conversion and Automation and Power Engineering; Electronics and Telecommunications and Computer Technique, Information and Automatics.
DPE .PCA
Two of them deals with the Electrical Power Engineering: Power Engineering (PE) and Power Conversion and Automation (PCA). Because of fast of electronics (specially development microelectronics), information technologies, and communications and their influence in modem life , the student interest is focalized in these new argument and the more traditional directions are not attractive compared with the two other directions . In Fig. I is shown first year students interest for all directions in last two school yt:ars at the Faculty of Electrical Engineering - Skopje .
[JET [JCTIA
97/98
98/99
99/00
Fig. I Student interest for directions at FEE - Skopje From the other s ide, the industry needs well prepared engineers in all electrical engineering branches, who are familiar with new technologies implemented also in power electrical engineering.
253
If industry requires well-prepared engineers in this field, it is responsibility of universities to fulfill this need. Coupled with employment opportunities and the infusion of power electronics and controls, the traditional subjects became more attractive and both industries and students could benefit. f The electrical drives course it is only one example of how it was possible join traditional subject as Electrical Motor Theory and newer microelectronic-controlled power supply in high performance motor control to turn the crisis in traditional power engineering courses into an opportunity.
The participants from the EU side are: University of Surrey - UK (prof. David Hamill and prof. Keith Bateson), Universidad Politechnica de Madrid Spain (prof. Javier Uceda, prof. Jose Cobos and prof. Fernando Briz) and Universita Degli Studi di Milano - Italy (prof. Piero Maranesi and prof. Marco Riva) . Every foreign professor has an alternative with professor from Faculty of Electrical Engineering Skopje, Macedonia (prof. Tomislav Dzekov, prof. Ljupco Panovski, prof. Goce Arsov, assistant Goce Sutinovski, prof. Ljupco Karadzinov, prof. Metodija Kamilovski and prof. Slobodan Mircevski). From the macedonian side also participate enterprises: Rade Koncar -Foreign Trade and EMO - Automation & Electronics and Macedonian National TEMPUS Office.
I. 2 Importance a/electric drives
The electric drives are the greatest consumers of the total produced electric energy and their automation is the base for higher quantity and quality of production. In the US electric motors consume about 65% of the total electric energy production. It is clear that electric drives are the important criterion for industrial and technology development of a country . So, the electric drives need corresponding attention at education in electric engineering.
2.2 Undergraduate courses In the first year of the project the undergraduate studies existing courses in power electronics were reviewed and the four new subjects were introduced . I. 2. 3. 4.
A electric drives is a system which combines work machine with electri c motors. power electronics and controls. However the main aim is to control speed and position of mechanical loads. The need for electric drives is obvious to anyone civilized person . There has been a quite evolution underway in the process - control industry where hydraulic drives are being replaced by electric drives. Robotics and factory automation have become vital for the industrial competill\ <:ness in the global market of today. Electric transportation, including electric vehicles such as automobiles and buses, requires electric drives . The cost of wasted energy and environmental pollution are increasingly important concerns. Energy savings and flexibility by using power electronics is proved in industrial drives practice. These applications combined represent a huge market need.
2.
Power semiconductor devices Generic power electronic circuits High frequency and resonant converters Practical converter design considerations.
Also subjects are in the last (fifth) year of studies as optional. Because of different background in electronics and different power electronics needs in different directions the first two courses are optional for the student at PE, PCA and ET. The last two are only for the student at ET direction .
2.3 Postgraduate courses In the academic 1999/2000, the postgraduate courses were established, at a new postgraduate direction Power Electronics. The student interest were very good (20 students) and there were students who have graduated at all existing branches at Faculty of Electrical Engineering - Skopje. The students distribution depend on direction is shown in Fig. 2.
THEMPUS - PHARE JEP "DEVELOPMENT OF POWER ELECTRONICS COURSES" CTIA 5%
2. 1 Project outline The aim of the THEMPUS - PHARE J EP-121 03-97 "Development of power electronics courses" (1998200 I) is to satisfy the need of Macedonian industry for the adequately educated electrical engineers who can manage with the practical problems in industrial plants. In the project the existing courses in power electronics and related areas have to be reviewed and the new subjects at the undergraduate and postgraduate studies have to be developed.
PE 20%
PCA 15% 60%
Fig. 2 Students distribution depend on direction There are eight subject in this level:
254
I. 2. 3. 4. 5. 6. 7. 8.
Intelligent systems in power electronics. Introduction: Expert Systems; Fuzzy Logic; Neural Networks , Evolutionary Programming. Design for Compliance with Standards. Introduction to Electromagnetic Compatibility (EMC); Basic Electromagnetic Principles; EMC Requirements for of Electronic Systems; Nonideal Behavior Components; Radiated Noise and Susceptibility; Conducted Noise; Grounding; Shielding; EMI in Switched Mode Power Supplies; Intrinsic Noise Sources.
Simulations in Power Electronics PWM Techniques in Power Electronics Power Electronics Components and Integration Power Electronics Applications Modeling of Electric Drives Microprocessors and Digital ICs for Control in Power Electronics Intelligent Systems in Power Electronics Design for Compliance with Standards
The students choose seven subjects and after passing them they have to do their MSc. thesis to finish their studies.
2.5 Laboratory equipment 2." Subject ~y/labuses
The realization of the developed subjects was in tight connection with practical measurements and training. For this purposes in the last two years about 50000 US$ were spent for the student laboratory equipment. The most of equipment was bought from the German firm "WUEKRO electronics" .
The main topics of each postgraduate subject are : Simulations in power electronics. Introduction ; Simulation in Design Process; Frequency Domain versus Time Domain Analysis; Challenges in Simulation ; Classification of Simulation Tools and Historical Overview: Issues in Numerical Solutions; Overview of some Widely Used Simulation Programs; Overview of Simulator Capabilities by Examples; Power Semiconductor Device Models for Circuit Simulation: Conclusion.
The laboratory equipment is suitable both for training purposes, so as investigation works in MSc thesis . From the aspect of the purposes the main equipment can be divide in the two segments: general power electronic components and electric drive . General power electronic components. As an elements for general power electronic circuit were bought: Power electronics components, Rectifier circ uits, DC chopper and AC Power Controller with accessories and motors.
PWM Techniques in Power Electronics. Introduction ; DC to AC Power Conversion; Introduction to Space Vectors: Perform ance Criteria; Open Loop Schemes; Closed Loop Schemes; Multilevel Converters; Current Source Converters.
Electric drives modules. The electric drives modules are consist of: Braking module with : DC shunt machine, Eddy-current brakes and dynamometer with control units ; AC drives test unit with : Three phase squirrel-cage induction motor; Simovert 6SE70 and M icromaster frequency converters and DC drives test with : DC shunt machine; Simoreg K converter; controller with P, I and D variable components; Setpoint potentiometer; Control deviation units (for speed and current loops) with accessories .
Power Electronics Components and Integration. Practical Energy storage Elements; Magnetic Components Design; Advanced Power Semiconductor Devices and Circuits; Hybrid Power Electronics Circuit ~. Power electronics application. Introduction; Switching DC Power Supplies; Power Conditioners and Uninterruptible Power Supplies; Motor Drive Applications; Residential and Industrial Applications; Electric Utility Applications; Optimizing the Utility Interface with Power Electronic System.
3.
Modeling of electric drives and machines. This subject will be present in details in the next heading.
COURSE "MODELLING OF ELECTRIC DRIVES"
3.1 Course outline
Microprocessors and Digital ICs for Control in Power Electronics. Introduction; Microcomputer of Power Electronics Systems ; Control Microcomputers basics: Real-Time Using Microcomputers; Microcontrollers; Advanced M icroprocessors for Control of Power Electronics Systems; ASIC for Control of Power Electronics Systems; Design of Microprocessor-Based Control Systems; Development Tools; Application Examples.
In the undergraduate studies the courses of electric machines and electric drives exist only in PE and PCA directions . The students from the other directions have no any exam in this area. The students from ET direction, at the moment, have no any course in control techniques area in under graduate studies. Because of that the postgraduate course "Modeling of electric drives" should cover
255
electric machines, power electronics and controls on an "as-needed" basis. The course had to be based on space-vector theory approach and tools for modem control - state space, digital, adaptive, robust and intelligent control systems. In view of societal needs, the main goal was to develop a course which will interest a large segment of the electric engineering postgraduates (16 students). It should also be of interest to other students from mechanical and civil engineering disciplines where electric drives are used for applications in process control, robotics and transportation (Riva M., 2000).
motors ; The different control schemes for AC supplied DC adjustable drives and schemes for DC to DC adjustable drives are explained. Synchronous Machine Vector Control (3 lectures). This section covers: The advantages of AC vs . DC drives ; Advantages and disadvantages of synchronous vs . induction machines; The voltage and current source inverters with the basic control topologies ; The basic principles of vector control strategy, dynamics of synchronous machine in vector control with its implementation in drives; The brushless AC motors, their mode ling, field oriented and basic control schemes.
32 Course Syllabll.1 Induction Machine Vector Control (4 lectures). The basics of induction machine vector control ; Implementation of direct and indirect field orientation, dynamics of FO induction machine and torque control requirements ; The different control strategies (current regulated CSI and PWM inverters, hysteresis regulator, ramp comparison controller, stationary and synchronous frame regulators, feed forward and augmented feed forward compensation, predictive control); The small signal analysis with machine equivalent circuits, equations and stability analysis ; The induction motor control based on small signal model in this section are explained.
The course consist of 12 heading which give to students basic principles of electrical machines, working machines, control techniques and application of electric drives. The main topics are briefly described in the following sections. Space-vector Theory Approach (2 lectures). The knowledge of space vector theory is a basic for the electrical machine analysis. In this section the basic postulates of the theory is given. The equations of different electrical elements and their presentation in dynamic and quasi stationary regimes. The transformation of rotating quantities (e.g. rotor windings, current) and the relationship with the generalized electrical machine theory is presented.
Observers and Estimators (3 lectures). The different types of indirect and direct controllers for induction motors are introduced and their implementation are explained.
Induction Machine (3 lectures). The induction machines is the most used in electric drives . In this section basic concept of different types of induction machines and the function principles; Full and reduced order model of induction motor in space vector and reference frame theory: The basic induction motor regimes with circuits and equations (start up, steady state and braking); The operation with sinusoidal and non sinusoidal voltage supply with the emphasis on variable frequency power electronic supplies are presented.
of Working Speed-Torque Characteristic Mechanisms and Electric Motors (I lectures). In this section: The basic elements of electric drive ; Operation modes; Load torque and classification; Coupling of Working Mechanism with Electric Motors ; Dynamics of drive system and steady state stability are explained. Parameters Estimation (2 Synchronous Motor; Tests Determination of stator and constants and drive inertia are
Svnchronous Machine (3 lectures). This section covers following items: The basic principles of synchronous machine; Steady state and transient operation; Variable frequency synchronous machine; Naturally commutated synchronous motor drives; Permanent- magnet synchronous motor - principles model and control.
lectures). Tests for for Induction Motor; rotor parameters, time given.
DTC for Asynchronous motors (2 lectures). Direct Self Control Regulator; Speed regulator; Direct torque control; Advantage and Disadvantage of DSCDTC; Switching, Commutation; Predictive scheme; Sensorless applications; Open loop methods, MRAS ; Observers for DTC are explained.
DC Motors (2 lectures). The main usage of DC motors are in adjustable speed drives . Induction motors are more reliable and cheaper and in the last years with development of power electronics and control techniques DC motors are replaced by the induction motors. That why this section is shorter than previous. In this section: Basic construction and operating principles for the different types of DC
DTC for Synchronous motors (2 lectures). This section covers: DTC in Brushless applications; Flux and Torque estimators; Switch tables ; Sensorless application; Example of implementation ; Anisotropy machine.
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Drives for Specific Applications (3 lectures). This section covers: Energy Saving Possibilities in High Power Drives: Cranes and Hoist Drives; Machine Tools: Steel Rollin g Mills ; Cement Mills: Sugar Mills: Textile Mills : Coal Mines drives.
IEEE video tutorials "The history of Power Converters in Motor Control" by W. McMurray and "Adjustable Speed Drives" edited by S.J. Salon was translated and titled in macedonian and they was presented to our students. We also used other video cassettes by different equipment vendors as: ABB, FLUKE, EMO, BAKER to give information to students in industry applications.
Laboratory training. Laboratory training course was organised in three part: I. ., 3.
Real equipment exercises: Simulation exercises and Video tutorial s.
Into consideration that the most of students were employed there was no need of industry visits or other kind of practice. For unemployed students visit to different industrial plants concerning application of electric drives could be arranged.
Real equipment exercises. This exercises had to be done using the existing equipment in laboratory for electric drives at Faculty of Electrical Engineering and the new bought for the lEP purposes.
In this moment the course "Mode ling of electric drives" to the student is present in the classical way with teaching lessons and exercises in the laboratory. Because the most of students are employed in the industry and don't live in Skopje there were problems for the students to be on lessons . Today with intern et resources developed in Macedonia and FEE the solution for this problems is implementation of the distance learning. Of course, distance learning is suitable for theoretical and simulation parts of the course, but its implementation will be useful for the students, which can not be on lessons and also for the all students when they will prepare the exam.
The existing equipment suitable for this course are : 2 DC converters for -l quadrant drive ; I Converter for 4 quadrant drive, realised as load imitator with DC motor; 2 analogue frequency-voltage converters for IM and I DTC frequency-voltage converter. The converters are equipped with their own measurement instruments and also have specially realised measuring points for oscilloscope. The specification of new acquired previous section of this paper.
IS
given in
The measurement equipment is a necessary, important and expensive part of a laboratory for electric drives. New instruments for measuring Voltage , current, frequency, resistance, inductance are acquired, in c luded analogue and digital oscilloscopes.
The good basics for this can be online course In electric drives developed at the Politecnico di Milano, Italy (http://corsi.metid.polimi.it) (Castelli Dezza F. at aI., 1997) and interactive CD which IS included with (Boldea I at al. 1998).
4.
Simulation exercises. The basic concept of simulation exercises is usage of most popular simulation packages. Because of existing course "Simulations in power electronics" in which are given basics in simulation, in course "Modeling of electric drives" are realized only Jl!dicated exercises which covers the most of course sections.
CONCLUSION
In the modem industry application electric drives are one of the most important parts. The modem drives includes knowledge of electric machines, power electronic and control systems and techniques. The classic electrical power engineering directions at Faculty of Electrical Engineering - Skopje, Republic . of Macedonia had problems with the students interest, because of fast development of computer sciences and telecommunications, made more attractive courses which involved information technologies and microelectronics.
The most of exercises were done using MatlabSimulink as the most popular and most suitable for control drive simulation (Castelli Dezza, at al.. 1997), and using Mathcad and PSpice (Mircevski and Andonov, 1998). Useful tools for the simulation exercises were IEEE self-study courses: Adjustable speed drives (Stessing and Celanese, 1998) and Modem Control Systems (Masten , 1995).
The aim of THEMPUS - PHARE lEP "Development of power electronics courses" is to improve the under and post graduate studies in segment of power electronics which application in most cases is electrical power engineering. It is really to expect that this project should turn the crisis in traditional power engineering courses into an opportunity.
Video tutorials. Membership in IEEE. Industry Application Societ; was a great positive experience. The basic ideas about video tutorials were obtained of IEEE Video Program .
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The postgraduate course "Modeling of electric drives" was developed to help student to understand electric drives and their application. The course was designed for students with various background which means that there is no need of basic knowledge in electric drives. It has theoretical and practical sections. As a proof of the slIccessful course concept is the excellent student interest in the first year of postgraduate studies (80 %).
REFERENCES Boldea I, Boldea A. and Nasar S. A. , Electric drves, CD ROM interactive, CRC Press, USA, \998. Castelli Dezza F., E. Chiesa, A. Monti and M. Riva (\997) . Using a new interactive Matlab® Toolbox for Control Design and Teaching of Electrical Drives. EPE 97 Trondheim, Norway. VollI, pp. 1008-\0\3 . Leonhard W. (\998) . Electric energy in the information age - an indispensable commodity. 10th EDPE, Dubrovnik. Croatia. pp. 1-8. Masten M, K. (\995) . Modern Control Systems, Self study-course. IEEE, Piscataway, USA . M ircevski S. A. and Z. Andonov (\998). Modern laboratory trammg in electric drives . MELECON, Tel Aviv, Israel. pp. 155-\60. Mohan N., T. Underland, M. Riaz and V.D. Albertson (\996) . Teaching an introductory course on electric drives using space vectors, without the prerequisite of electric machine theory. PEMC 96. Budapest, Hungary. Vo!. 3, pp. 20-3\ . Moreira 1. C. , T . A. Lipo and V. Blasko, (199\). Simple Efficiency Maximizer for an Adjustable Frequency Induction Motor Drive. IEEE Trans. Industry Applications, vot. 27, No. 5, pp.940946. Novotny D. W. , T. A. Lipo (1996). Vector control and dynamics of AC dives , Clarendon press. Oxford, UK. Riva M. , (2000) . Hodelling of electric drives. JEP Development of Power Electronics Courses. Stessing W. and H. Celanese, (1998). Adjustable speed drives. Self-study course. IEEE, Piscataway, USA . Vas P. (\996). Electric machines and drives. Clarendon press, Oxford, UK.
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