EPE Journal Volume 06-3/4 
 You are here: EPE Documents > 02 - EPE Journal Papers > EPE Journal Volume 06-3/4 
EPE Journal Volume 06-3/4 - Editorial
EPE Journal Volume 06-3/4 - Papers



 EPE Journal Volume 06-3/4 - Editorial 

5 seconds for a better future  [Details]
By B. Sneyers

The Editorial of the EPE Journal Volume 06 N°3/4, "5 seconds for a better future", written by Ir. Brigitte Sneyers, the Secretary General of EPE Association


 EPE Journal Volume 06-3/4 - Papers 

Protection Concepts for Rugged IGBT Modules  [Details]
By S. Konrad; I. Zverev

A reliable protection concept is an important component in any design of the power conversion system. The classification of the critical operation cases, that can lead to the destruction of the power semiconductor, is presented. On the basis of the measured waveform the short circuit type II is pointed out as the worst fault case. With the consideration to the main emphasizes of integration very reliable and good integrable protection circuits are introduced. A new two-stages approach to control the gate-emitter voltage and a switchable gate resistane control are the special features of the protection concept. The comparison of the forward and short-circuit behaviour of the IGBTs with different channel lengths shows the trade-off between the power losses and the rugedness.

Optimization of the Short-Circuit Behaviour of NPT-IGBT by the Gate Drive  [Details]
By H.-G. Eckel; L. Sack

Short-circuit withstand capability is an important feature for IGBT in inverter applications. With NPT-IGBT, the stress for the device is especially high if the short-circuit occurs while the device is carrying a current (short-circuit type II). In this case, a high current peak and a large overvoltage can occur. In this paper, a model for the dependence of the current and voltage stress of a NPT-IGBT is given. It shows that the voltage stress is especially high for IGBT with a high rated current. A new gate drive concept, the di/dt controlled gate clamping, that reduces the current and the overvoltage is investigated on. This gate drive concept is combined with a concept for turn-off of the steady-state short-circuit. Experimental results show that safe operation in every short-circuit situation is possible.

A Multilevel Rectifier with Unity Power Factor and Sinusoidal Input Current for High Voltage Applications  [Details]
By N. Aouda; L. Prissé; T.A. Meynard; H. Foch

This paper presents a single-phase multilevel a.c./d.c. converter and its application as a synchronous rectifier operating at near unity power factor and drawing a quasi-sinusoidal current from the utility source. The proposed rectifier is based on a reliable series connection technique of semiconductors making it particularly suited for high-voltage and low line-current distortion applications. The multilevel rectifier operating principle, specific features, and control strategy are discussed. Simulation and experimental results for steady-state and different transient conditions corresponding to a 1.5 kV, 4 kW laboratory prototype are also presented.

Analysis, Design and Evaluation of a High Performance PWM a.c./d.c. Converter Providing Sinusoidal Current with Unity Power Factor  [Details]
By I. Fatouh El-Sayed

The ability of the PWM converter schemes to operate as a linear amplifier, in both regenerative and rectifier applications, is an important issue. The PWM voltage converters are increasingly called upon to fulfill the duties of filtering, stabilization and dynamic performance enhancement. However, the straightforward power angle control (PWM pattern position) of the converter is characterized by a slow response and stability problems. This paper describes, analyzes and verifies a stand-alone, constant power factor, controlled unit converter. The proposed scheme employs a PWM voltage type converter and has important characteristic, that is, the operation with variable power angle and modulation index (PWM pattern weight). By realizing this property, the converter can provide sinusoidal input current with constant power factor (e.g. unity p.f.) and exhibits fast transients response. This paper presents a comprehensive approach to the quastion of the design criteria and closed form equations for PWM converter that demands sinusoidal current with constant unity power factor and at the same time provides high quality output d.c. current. The principles of operation along with the design criteria of the power circuit components are discussed in detail. Most features of teh converter are clearly interpreted for resistive and dynamic loads. On the basis of the given analysis, the paper provides the design guidelines for the PWM converter. Also, a novel control strategy is proposed, which allows to fulfill all the specifications; in particular zero reactive power demand and very low current ripples for rectifier and regenerative operations. The proposed method in this paper utilizes simultaneously the control variables: modulation index D and power angle delta. The instantaneous control for both achieves high-dynamic response, power factor adjustment capability and insensitiviness to parameter variations and disturbances. Also, the proposed scheme provides a low cost solution for d.c. and a.c. drive applications. This paper provides a complete analysis of the converter, interesting design criteria and equations, and design example. Finally, SPICE simulation and experimental time domain results are investigated.

Power Factor Correction Using Zero-Current-Switched Quasi-Resonant Converters with Voltage-Follower and Multiplier Approach Control  [Details]
By J. Sebastián; J. A. Martínez; M. M. Hernando; J. A. Cobos; F. Aldana

In this paper we propose to study the use of Zero-Current-Switched Quasi-Resonant Converters as Power Factor Preregulators with two possible types of control: multiplier approach control and voltage -follower approach control. The former allows us to obtain almost ideal operation, but requires switching-frequency modulation each line half-cycle, input current feedback loop and specific controller. The latter allows us high power factor (0.98 - 0.96) and low total harmonic distortion (15 - 26%) with a very simple control method which can be implemented with a standard controller.

A Three-Phase Four-Wire Shunt Active Filter Employing a Conventional Three-Leg Converter  [Details]
By M. Aredes; K. Heumann; J. Häfner

This paper will be available soon. - A three-phase four-wire shunt active power filter using a conventional three-leg converter is presented. It needs no power supply at the d.c.-bus and the a.c.-neutral wire is directly connected to the electrical midpoint of the d.c.-bus. This power circuit configuration has been named "split-capacitor" topology (fig. 1). The active filter controller considers harmonics, reactive currents, as well as unbalances due to negative and zero-sequence components at a fundamental frequency. The goçal is to provide balanced sinusoidal currents to the source, even under unbalanced voltage conditions. Some simulation and experimental results are presented to validate the proposed control strategy.

See as well the "Remarks to the paper "A Three-Phase Four-Wire Shunt Active Filter Employing a Conventional Three-Leg Converter", published in EPE Journal Volume 07-3-4" by Dr. Ing. V. Staudt.

Vector Control of a Variable Speed Doubly-Fed Induction Machine for Wind Generation Systems  [Details]
By R. S. Pena; J. C. Clare; G. M. Asher

Control techniques suitable for a doubly fed induction generator applied to a wind generation system are presented. A Scherbius scheme using two back-to-back voltage-fed current-regulated inverters in the rotor circuit is employed allowing subsynchronous and supersynchronous operation with low distortion currents. A vector control scheme using a reference frame oriented along the stator flux vector is used for the machine. This leads to independent control of the electrical torque and the rotor excitation current. A vector scheme aligned with the stator voltage vector is used to control the stator-side converter; it gives indepenent control over the active and reactive power flow between the supply and the stator-side converter. The control strategies are tested with the machine working as a variable speed constant frequency generator driven by a wind turbine emulator. Two approaches for optimum speed tracking of the wind turbine are implemented and experimental results for a prototype system are presented.

A Refined Detection of a Reference Signal for Converter Controls under Distortion and Frequency Excursion  [Details]
By M. E. Abdel-Karim; A. I. Taalab

The paper describes a novel technique of how a sinusoidal reference signal synchronized to an a.c. system network, of distorted waveforms and of large frequency variations, can be obtained. A second order bandpass switched capacitor integrated circuit filter is used to produce a sinusoidal signal locked to the distorted input signal. The locking is achieved via automatically controlling the filter center ferquencies using a phase locked loop. Effect of the filter clock frequencies, quality factor and tuning are discussed. How a frequency independent fixed phase shifts, which can be used for measurements of different power system quantities, can be obtained using the proposed technique is presented. The effects of using the zero crossing pulses obtained from the detected sinusoidal reference signal, under distortion conditions on the performance of a single phase converter control is given.

Development of an Expert System for Design Purposes in Power Electronics  [Details]
By D. Fezzani; H. Piquet

This paper presents a way to formalize interactions that systematically exist between components of an electrical system. It is obviously one of the fundamental points to create an expert system dedicated to design. The study is based on the usual approach of a generic structure characterizing an Uninterruped Power Supply (UPS) which was chosen as support to develop an automatic procedure. First, the authors describe the design methodology, then present the expert modules dedicated to the definition of different constitutive elements of this UPS. These modules are implemented on a computer by use of the "expert system shell" SMECI. The results of this approach are illustrated by an application example for precise specifications.