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EPE Journal Volume 09-3/4 - Papers
- An Experimentally Validated Transient Thermal Impedance Model for High Power Diodes and Thyristors
- Design of a Single-Stage ac/dc Converter for Low Power Level Applications
- Stability Analysis of Multilevel Converters with Nested Cells
- Resonant Converter as a High Pressure Sodium Lamp Ballast
- A Sensorless Vector Control Scheme for Induction Motors using a Space Phasor based Current Hysteresis Controller
- A Novel A.C. Voltage Regulator
- Using Multimedia in Variable Speed Drive Teaching
- Remarks to the Paper: White Paper on the New ABB Medium Voltage Drive System, Using IGBT Power Semiconductors and Direct Torque Control, Vol 7-3-4, pp 40-45
EPE Journal Volume 09-3/4 - Editorial
By M. Jufer
The Editorial of the EPE Journal Volume 09 N°3/4, "EPE '99 - Lausanne, a Review", written by Prof. Marcell Jufer, the Conference Chairman of EPE '99.
EPE Journal Volume 09-3/4 - Papers
By F. Profumo; A. Tenconi; S. Facelli; B. Passerini; A. Guerra
In this paper a thermal model that allows to obtain the transient thermal impedance curve of high power diodes and thyristors is presented. The results obtained from the model are compared with the experimental measurements performed on the most diffused families of device packages. In the last section of the paper a method for predicting the transient junction temperature by using PSPICE is outlined. The method is based on the fitting of the transient thermal impedance curve with a finite series of exponential terms.
By J-Y. Lee; G-W. Moon; M-J. Youn
This paper will be available soon. The design of a single-stage a.c./d.c. converter operated in discontinuous conduction mode (DCM) for low power level applications is proposed. The proposed converter gives the good power factor correction, low line current harmonic distortions, and tight output voltage regulations. This converter also achieves a high efficiency by employing and active clamp method and synchronous rectifiers. The modelling and detailed analysis for the proposed converter are performed. To verify the performances of the proposed converter, a 90 W-converter has been designed. This prototype meets the IEC 61000-3-2 requirements satisfactorily with nearly unity power factor and high efficiency.
By J.L. Duarte; L.J.J. Offringa; W.D.H. Van Groningen
This paper will be available soon. - By taking the influence of parasitic components explicitly into account, a small-signal sampled-data description of a multi-level converter with clamping capacitors is derived. Insted of stressing numerical solutions, the derivations are worked out following an analytical formulation. Although attention is paid to a three-level chopper, the modelling approach is appropriate to other multilevel converters as well. Simulation results and experimental measurements confirm the validaty of the proposed model.
By F. Ferrero; M. R. Secades; C. Blanco; M. A. Pérez; J. C. Campo; M. G. Vega; J. C. Antón
This paper will be available soon. - Analysis and design of a single-stage electronic ballast with unit power factor are presented in this paper. The proposed single-stage ballast is the combination of a boost-converter and a full-bridge series-resonant parallel-loaded inverter. The boost semi-stage working in the discontinuous conduction mode functions as a power factor corrector and the inverter semi-stage operated above resonance is employed to the ballast lamp.The fundamental approximation is used in points where the commutations are optimum and the reactive energy that the inverter handles is nil. The proposed lamp-ballast can save a controller, reduce size and possibly increase system reliability over a conventional two-stage system. Experimental results from a lab prototype are used to verify the design procedure.
By V. Ebenezer; K. Gopakumar; V. T. Ranganathan
This paper will be available soon. - The increased use of a.c. machines compared to d.c. motors in electrical drive applications has several reasons. A very important advantage of a.c. machines is their simple construction. However, a.c. drives often need mechanical sensors (tachometers, position encoders) for field orientation. In many applications these sensors reduce robustness and increase costs of a drive considerably. The objective of this paper is to present the practical implementation of a Sensorless Vector Control Scheme for Induction Motors using a Space Phasor Based Current Hysteresis Controller. This scheme measures the stator current hysteresis error direction to determine the rotor flux position, during inverter zero vector states. This measurement of the rotor flux position is done indirectly by sensing the motor back emf, which is orthogonal to the rotor flux position. The basic idea is to measure the current hysteresis error direction of the stator current on the application of an inverter zero vector, i.e. "short circuit at machine terminals". A generalization is possible by a combination of two (different) active states of the inverter. By a linear transformation of the electrical equations for both inverter states, a mathematical zero state is constructed. The use of this virtual short circuit is necessary at higher speeds when the inverter output voltage is fully utilized. However, at low speeds the drop across the stator resistance is comparable to the motor back emf, to overcome this a simple parameter adaptation scheme is also presented here. The proposed scheme enables a smooth transition to six-step mode of operation.
The whole scheme is implemented using a Space Phasor based Current Hysteresis controller, in which the inverter voltage vectors close to the machine back emf vector is selected, without measuring the back emf vector. The back emf vector is sensed indirectly from the direction of the current error space phasor. A single chip solution is arrived at by using the TMS320F240 DSP.
By A. Zein El-Din; A. El-Sabbe
This paper describes a new single-phase controller for supplying resistive loads, with two different strategies. Load voltage is varied by controlling the flux linkage of a single transformer windings used with the proposed system. The primary of the transformer is connected in series with the load of the a.c. supply, while the secondary is shunted with a control device. The flux linkage is controlled by using either a pair of thyristor "triac" (phase controlled) or a MOSFET transistor (a.c. chopper topology). Simulation analysis of the two proposed methods of control are presented, and verified by experimental results in different cases of operation. The advantages of the proposed system are simple, effective, accurate, low distortion of supply current, smooth regulation of load voltage and low cost. The proposed system can be used in industry applications such as heaters, lighting control and a.c. drive controls.
By G. De Coninck; R. Reekmans; K. Hameyer; R. Belmans
The paper provides ideas and practical experiences using multimedia at the electrical engineering department in the field of electrical machines and variable speed drives. Using multimedia developments, it is possible to confront students in a more attractive and efficient way with Electrical Machines and Drives. The paper approaches the term multimedia from different points of view. The definition of a multimedia computer is explained and different authoring systems are presented. A practical example, visualisation of phenomena and construction of a squirrel cage induction machine, is looked at in a closer way. The conclusion is that the undergraduates get more interested and even recommend additional multimedia applications in other topics of electrical engineering education.
By B. K. Bose
The author is to be complimented for his excellent article. In fact, ABB's new IGCT device and the DTC (Direct Torque Control) base drive system are also described in [2] and [3], respectively. Unlike traditional drives, this system has indeed a number of novel features. However, I would like to make several comments...