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Expert Syst. Appl. 01/2011; 38:11911-11917.
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ABSTRACT: With the growing popularity of mobile devices, several projects for mobile learning courses have been developed. Those equipments allow a superior portability and accessibility of the learning courses. In this context, the present paper focuses on the development of a mobile learning framework for an analog electronics course. This course was designed as a supplementary mean to the classic analog electronics courses. The course project consists of several interactive multimedia modules. At the end of each module, students have several oriented questions to answer. The set of answers, in SMS format, gives feedback to the teacher about the learning process. Another module, that is under development, is responsible for storing and managing the answers in a server, where all the results from students are processed in a competitive learning based methodology application.
Education Engineering (EDUCON), 2010 IEEE; 05/2010
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ABSTRACT: The study of fault detection and diagnosis of electrical machines, in particular induction motors, as well as the teaching of their behavior requires practical experience in this field. To provide this experience to the students this paper presents an experimental system that can be used with a standard industrial electrical induction machine. This system is based on only one healthy induction machine that is operated under faulty operating modes. Several fault types such as stator winding faults, bearing faults, or broken bars can be tested. The developed system also allows testing the behavior of the electrical machine for different load types. Several typical loads in which the torque depends of time or speed were implemented. The system is based on computer equipment with a DSPIC, a testing system and an induction machine. © 2010 Wiley Periodicals, Inc. Comput Appl Eng Educ; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20429
Computer Applications in Engineering Education 03/2010; · 0.33 Impact Factor
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ABSTRACT: This paper proposes the use of the park transformation mass center applied to the stator currents as a method for diagnosing the occurrence of stator winding faults in induction motor. Induction motor stator currents are first measured and recorded. Then, the park transform is applied to the obtained currents in order to obtain a specific pattern that allows the identification of the stator winding fault. For a healthy motor, a single point in a dq-plane is obtained. However, for an induction motor with some stator winding fault one obtains a circle, in the dq-plane, which is dependent on the fault severity. Accordingly to this relationship a fault severity is reported. In order to show the applicability of the proposed technique, several simulation and experimental results are presented.
Industrial Electronics, 2009. IECON '09. 35th Annual Conference of IEEE; 12/2009
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ABSTRACT: In this paper a detection and fault diagnosis for a Voltage Source Inverter is presented. The need to insure a continuous and safety operation for voltage source inverter involves the need for reliable fault diagnosis techniques. The proposed approach uses an automatic three step algorithm. Firstly, the inverter output currents are measured which will give typical patterns that can be used to identify the fault. Secondly, the Eigenvectors/Eigenvalues of the 3D current referential are computed. Finally the proposed algorithm will discern if there is any fault and report the faulty switch. The proposed approach was experimentally implemented and its performance verified on various types of working conditions.
Industrial Electronics, 2009. IECON '09. 35th Annual Conference of IEEE; 12/2009
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ABSTRACT: This paper describes the MATLAB/SIMULINK modeling for a Stand-Alone Energy System Supported by Totally Renewable Hydrogen Production. The full modelling of a stand-alone Energy System is a huge task implying heavy computation models with long computation times. Therefore, the full modelling approach cannot be used for teaching purposes. In this way, this paper describes a simplified model that is being used in the renewable energies course at the Electrical Department of the Faculty of Sciences and Technology (Universidade Nova de Lisboa, Portugal).
E-Learning in Industrial Electronics, 2009. ICELIE '09. 3rd IEEE International Conference on; 12/2009
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ABSTRACT: In this chapter an image processing based classifier for detection and diagnosis of induction motor stator fault was presented. This system is based on the obtained stator currents and the correspondent Clark-Concordia transformation. This results in a circular or an elliptic pattern, of the Clark-Concordia stator currents. From the obtained current patterns it was used an image processing algorithm to identify if there is a motor fault. The image processing algorithm is divided in three stages: the image composition, the boundary representation and the feature extraction. For the the features extraction it was used two effective algorithms that can be used for the induction motor fault detection: Visual features and statistic based moments methods. The extract features of the the obtained current patterns allows to identify the turn faults in the stator winding and its correspondent severity. Several simulation and experimental results have been presented. From these results it was possible to verify that the proposed image based classifier can effectively be used for the diagnosis of induction motors.
12/2009; , ISBN: 978-953-307-026-1
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ABSTRACT: In this paper it is proposed a unity power factor isolated three-phase rectifier with buck-boost characteristics. This rectifier is based on the scott transformer and only uses two single-phase buck-boost rectifiers. In this way only two switches are used. To achieve sinusoidal input current and high power factor, a fast and robust pulse with sliding mode modulation of the input current is proposed. An output voltage compensator is also used to establish the amplitude of the reference currents. Several results are presented in order to show the effectiveness of the proposed rectifier.
Compatibility and Power Electronics, 2009. CPE '09.; 06/2009
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ABSTRACT: One of the most important issues on the power system course is the study of the transient power systems. However, due to the complexity of the power systems networks, for an effective instruction of this topic it is required to use a computed simulation environment to provide a complement to analytical methods. Therefore, a methodology for the modeling of power systems on the transient analysis using a Matlab/Simulink program is proposed. This methodology allows producing voltage and current transients that correspond to fault events, instabilities and the introduction of power electronics equipments in the power systems. Furthermore, this also allows students take advantage of the mathematical models they have derived to perform the desired simulation. Since state space models are used, this simulation tool is useful to study the transient phenomena and easier to compare with power systems laboratory results. So, students can understand how a simulation program have been developed, their capabilities and limitations. Several illustrative examples will be presented in order to clearly show the proposed methodology.
Power Engineering, Energy and Electrical Drives, 2009. POWERENG '09. International Conference on; 04/2009
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ABSTRACT: Commercial office buildings with renewable energies are becoming more important in the actual context. That integration cannot be seen isolated from the strategic transport planning. Under this context this paper presents an office facility, equipped with renewable energy sources, where the users can recharge their plug-in electric vehicles, using the available renewable power. The system controller is composed by a network of distributed local controllers interconnected to a server. This system manages the power transfer between the building and the parked electric cars, including full discharge battery procedures. An important feature of the system is that it manages the energy consumption of each user, and assigns the respective costs to the correspondent company.
Power Engineering, Energy and Electrical Drives, 2009. POWERENG '09. International Conference on; 04/2009
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ABSTRACT: This paper presents a novel grammatical flux estimator for sensorless AC-drives. The proposed methodology does not require the integration of the standard voltage model neither the exact knowledge of the system parameters. Assuming the flux estimator as a linguistic source, producing a certain language, a grammatical inference algorithm is used to extract the productions that govern the grammar representing that language. The formalism of the developed formal language based control algorithm is presented. The inherent non-linear characteristics of the grammar productions make it possible to obtain accurate flux estimation. Application results are presented in order to show the effectiveness of the proposed methodology.
Industrial Technology, 2009. ICIT 2009. IEEE International Conference on; 03/2009
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Eng. Appl. of AI. 01/2009; 22:192-200.
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ABSTRACT: In this paper a Web based teaching of electrical drives using a mechanical load simulator is presented. The developed system allows testing the behavior of an electrical machine for different load types. Several typical loads in which the torque depends of time or speed are implemented. In this way, using this tool it is possible to study the dynamic behavior of an electrical machine. It is also used to study induction machine fault diagnosis under different load types. The remote laboratory is based on an I/O interface controller and client-server architecture. To implement this system the software package MATLAB was used.
Industrial Electronics, 2008. IECON 2008. 34th Annual Conference of IEEE; 12/2008
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ABSTRACT: Dynamic voltage restorer (DVR) is known as an effective device to mitigate voltage sags and swells. This paper presents a control method based on the input-output linearization applied to the DVR. The synthesis of the parameters is presented. A new compensation voltage control is also proposed. This control is based on the Clark-Concordia transformation and a robust PLL structure. Several simulation results are presented. This allows showing the performance of the control method based on the input-output linearization applied to the DVR and the effectiveness of the compensation voltage control.
Computational Technologies in Electrical and Electronics Engineering, 2008. SIBIRCON 2008. IEEE Region 8 International Conference on; 08/2008
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ABSTRACT: The objective of this paper is to present a remote laboratory in the context of power electronics education. New technologies and developments are compelling educators to deeply reflect on the traditional means of teaching. Modern curricula require new ways of conception and implementation of innovative pedagogical approaches. Often, these new pedagogical approaches require novel technological realizations. Although e-learning facilities are increasingly being used in engineering education, often, they are based on simulations and/or emulations of virtual laboratories. This paper presents a remote laboratory facility that allows the students to conduct real power electronics reconfigurable experiments through the Internet, promoting a more efficient learning through online industrial automation operation using the Internet and WWW services.
IEEE Transactions on Industrial Electronics 07/2008; · 5.16 Impact Factor
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ABSTRACT: An on-line diagnosis method for three-phase induction motors using an automatic algorithm based on the analysis of the input current RMS is presented in this paper. This algorithm uses the spectrum of the input current RMS value and allows an interpretation of its magnitude as a severity index. Simulation and experimental results, for both an healthy motor and a motor with broken bars, are presented in order to show the effectiveness of the proposed method.
Instrumentation and Measurement Technology Conference Proceedings, 2008. IMTC 2008. IEEE; 06/2008
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ABSTRACT: In this paper, a single stage flyback pfc converter is used as a power supply of a testing distance relay system. The flyback pfc converter topology, operation and control are presented. A fast and robust sliding mode control of the input current is also presented. The sliding mode controller enables also high power factor and nearly sinusoidal input current. The dc output voltage of the converter is controlled by a proportional integral (PI) controller. Simulation and experimental results from a laboratory prototype are presented and discussed.
Power Electronics and Drive Systems, 2007. PEDS '07. 7th International Conference on; 12/2007
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ABSTRACT: Non-invasive diagnosis of induction machine stator winding turn faults is a well established technique, allowing accurate results and cost-savings. This diagnosis is based on the analysis of the machine input line currents. However inverter-fed machines are becoming a common solution for industrial purposes. Power electronics technological advances allow good performance with competitive costs. Closed-loop drives represent a problem when current based fault detection techniques are used because in this kind of drives the controller regulates the machine input current. In order to keep the detection procedure non-invasive one should monitor the machine input voltage. In this paper the αβ-vector approach fault detection method is extended to inverter-fed induction machines. Results are presented in order to fully understand the advantages of the proposed method.
Power Electronics and Drive Systems, 2007. PEDS '07. 7th International Conference on; 12/2007
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ABSTRACT: In this paper a new algorithm for the detection of three-phase induction motor stator fault is presented. This diagnostic technique is based on the identification of a specified current pattern obtained from the transformation of the three- phase stator currents to an equivalent two-phase system. This new algorithm proposes a pattern recognition method to identify induction motor stator faults. The proposed neuro-fuzzy approach is based on the index of compactness, and also indicates the extension of the stator fault. This feature is obtained throw the image processing and used as an input in the neuro-fuzzy classifier. Using the neuro-fuzzy strategy, a better linguistic knowledge and an accurate learning capability underlying the motor faults detection and diagnosis process can be achieved. Simulation and experimental results are presented in order to verify the effectiveness of the proposed method.
Industrial Electronics Society, 2007. IECON 2007. 33rd Annual Conference of the IEEE; 12/2007
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ABSTRACT: The practical tryout of a PLC controlled automation process is a well known problem. This paper presents a process simulation tool, developed under the windows operating system, which can be used with any type of programmable logic controller. The process editor is comprehensive and is easy to use. An inexpensive hardware interface is established between the serial port of a personal computer and the digital and analog inputs/outputs of the PLC.
Industrial Electronics, 2007. ISIE 2007. IEEE International Symposium on; 07/2007
