Convertisseurs multicellulaires série - Principe, équilibrage naturel et modulation triphasée

National audienc

Optimal PWM method for flux reduction in InterCell Transformers coupling double three-phase systems

International audienceParallel multilevel converters are interesting in high current applications, especially when the designers interleave the switching signals and make use of a special component used to reduce the phase current ripple: the InterCell Transformer (ICT). This magnetic component has a special design which is highly dependent on the magnetic flux flowing through them. In three-phase applications, multilevel PWM methods have a direct influence on the ICT flux. The aim of the paper is to compare some PWM methods to parallel multilevel converters regarding the ICT flux. An optimal PWM method is also developed

A Non-isolated DC-DC Converter with InterCell Transformer for Buck-type or Boost-type Application Requiring High Voltage Ratio and High Efficiency

International audienc

A Non-isolated DC-DC Converter with InterCell Transformer for Buck-type or Boost-type Application Requiring High Voltage Ratio and High Efficiency

International audienc

Design and Comparison of Inductors and Intercell Transformers for Filtering of PWM Inverter Ouput

International audienceThis paper presents an original design option dedicated to output-filtered pulsewidth modulation inverters used in uninterruptible power systems, embedded networks, or motor drives operating on long cables. It is based on the coupling of interleaved inverter cells by means of intercell transformers (ICTs) and is characterized by very good dynamic behavior on load transients, which is an important issue in such applications. ICT solutions are compared with the classical interleaved solutions using separate inductors. A specific design method is developed to achieve this comparison based on toroidal core shapes. The results obtained with a 600 V, 7.5 kW inverter show the usefulness of ICT-based designs, especially when nanocrystalline magnetic material is used; high specific power and very good dynamic performances are obtained

Positionnement des bobines de transformateurs de puissance minimisant les pertes cuivre/ Power transformer winding positionning to minimize copper losses

National audienceCet article étudie le positionnement de bobines de transformateurs de puissance haute fréquence. Les pertes cuivre dues à des effets de peau et de proximité sont analysées afin de choisir la meilleure configuration des spires à l'intérieur de la fenêtre de bobinage. Initialement, les résultats sont une application directe de la formule de Dowell. Ensuite, des simulations utilisant un logiciel de calcul de champs par éléments finis (FEA) confirmeront la relation entre la fréquence du courant, la largeur de la fenêtre de bobinage et la position de la bobine. Abstract This paper deals with the positioning of parallel windings in a high-frequency power transformer. Analysis of copper losses due to skin and proximity effects is performed in order to choose the best configuration of the turns inside the winding area. Initially results are a direct application of Dowell's formula. Later, FEA simulations confirm the relationship between current frequency, core window width and winding position

New power converter topologies using InterCell transformers

International audienceCet article présente de nouvelles architectures de convertisseurs électroniques de puissance basées sur le principe de l'entrelacement de cellules élémentaires de conversion couplées et interconnectées par l'intermédiaire de transformateurs intercellulaires. L'intérêt de ces structures en matière de puissance volumique est démontré dans trois familles d'applications. Abstract This paper deals with new architectures for power electronics converters. These architectures are based on interleaved elementary power conversion cells interconnected and coupled using intercell transformers. The advantages of such architectures are demonstrated through three kinds of applications

Interactions Between Fuel Cells and Power Converters : Influence of Current Harmonics on a Fuel Cell Stack

International audienceAs fuel cells are likely to be used in many future applications, dedicated power converters must be developed and optimized. A thorough knowledge of the fuel cell operation is thus required for power electronics engineers. This paper proposes a theoretical and experimental study of the behavior of a fuel cell stack subject to current harmonics. The fundamental role of the internal double layer capacitor is demonstrated

Step-Down Partial Power DC-DC Converters for Two-Stage Photovoltaic String Inverters

Photovoltaic (PV) systems composed by two energy conversion stages are attractive from an operation point of view. This is because the maximum power point tracking (MPPT) range is extended, due to the voltage decoupling between the PV system and the dc-link. Nevertheless, the additional dc-dc conversion stage increases the volume, cost and power converter losses. Therefore, central inverters based on a single-stage converter, have been a mainstream solution to interface large-scale PV arrays composed of several strings connected in parallel made by the series connections of PV modules. The concept of partial power converters (PPC), previously reported as a voltage step-up stage, has not addressed in depth for all types of PV applications. In this work, a PPC performing voltage step-down operation is proposed and analyzed. This concept is interesting from the industry point of view, since with the new isolation standards of PV modules are reaching 1500 V, increasing both the size of the string and dc-link voltage for single-stage inverters. Since grid connection remains typically at 690 V, larger strings impose more demanding operation for single-stage central inverters (required to operate at lower modulation indexes and demand higher blocking voltage devices), making the proposed step-down PPC an attractive solution. Theoretical analysis and an experimental test-bench was built in order to validate the PPC concept, the control performance and the improvement of the conversion efficiency. The experimental results corroborate the benefits of using a PPC, in terms of increasing the system efficiency by reducing the processed power of the converter, while not affecting the system performance