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The supervision of semiconductor power devices in operation demonstrates an obvious interest to improve the operating safety of electronic power converters used in critical applications. Unfortunately, this is a significant challenge due to the variability of stress conditions on the one hand and to the difficulty to implement accurate measurement systems in power stages on the other. Using VCE measurement as a real-time supervision method is evaluated here by using aging test results obtained on insulated gate bipolar transistor (IGBT) modules stressed by power cycling. These results are related to the aging of bond wires and metallization, on the top part of the module. Results were obtained in original test benches whose characteristics are overviewed briefly in the first part of this paper, along with a description of test conditions. The second part presents selected results extracted from a larger work and focusing on the VCE evolution with respect to degradations of the module's top part. Their analysis highlights the potential of VCE measurement. The last part proposes the principle of a specific system able to achieve real-time VCE supervision in the test benches in operation. [ABSTRACT FROM PUBLISHER]

This paper proposes a converter topology dedicated to the interconnection between low voltage and high voltage networks or power sources. This topology uses the interleaving principle whose advantages are well known at this point. Its originality stems from the implementation of an isolating intercell transformer (ICT) that provides isolation, filtering, and intercell coupling through a single magnetic stage. The first section of this paper presents two ways to build bidirectional multicell converters, based on classic buck (or boost) cells on one hand, and buck-boost cells on the other. From the nonisolated versions of these two families, the synthesis of isolated versions is achieved by introducing classic two-winding coupled-inductors or transformers. A nonbidirectional isolated ICT version derived from the buck-boost family, the multicell ICT flyback converter, has already been studied and tested. Therefore, the second section describes the isolated multicell ICT converter derived from the buck (or boost) family and constitutes the main contribution of this paper. Its very interesting features regarding high step-up ratio requirements are emphasized, particularly by considering some limitations of the ICT flyback converter. Finally, a 10-kW test bench is presented. This test bench includes eight cells and an ICT created with separated transformers, making it possible to validate converter operations under realistic power conditions. [ABSTRACT FROM AUTHOR]

This 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. [ABSTRACT FROM AUTHOR]

This paper presents the developments and the results of an analytic method elaborated to design isolated intercell transformers. These particular magnetic components are intended for multicell interleaved flyback converters recently proposed and well-suited to low-voltage, high-power applications. A specific 2-D model to evaluate the winding losses is included in the design process. The results, obtained for standard core shapes, allow defining the ranges of the main parameters, number of cells, and switching frequency, required for future realizations. [ABSTRACT FROM AUTHOR]

Interleaved power converters are now used in many different conversion systems involving various topologies (series or parallel) and related to different fields or loads. This paper deals with interleaved parallel commutation cells using coupling transformers with a possibly high number of cells. The first part of the paper is a reminder of the basics of magnetic couplers addressing monolithic as well as distributed implementations. The limits associated with the conventional supply of such couplers (supply voltages forming a direct polyphase system) are described. In the second part of the paper, an optimized voltage supply improving the performances of the system is introduced. Experimental results obtained on a seven-cells test bench validate the approach. [ABSTRACT FROM AUTHOR]

The induction heating principle has been successfully introduced for about 20 years in domestic cooking appliances. The technical developments now concern the improvement of the current appliances and the introduction of new functions. So, one tendency is the design of multiwinding induction coils that are very adaptive concerning the shape and the power capability. This paper describes different original converter topologies designed to supply multiwinding coils, and, in addition, multicoil systems. The proposed topologies are based on particular use and associations of zero-voltage switching series-resonant converters. They are all characterized by a frequency-synchronized operating mode, in order to prevent any acoustic harm that could result from beating frequency-interferences. [ABSTRACT FROM AUTHOR]

The test and the characterization of medium or high-power electronic converters, under nominal operating conditions, are made difficult by the requirement of high-power electrical source and load. In addition, the energy lost during the test may be very significant. The opposition method, which consists of an association of two identical converters supplied by the same source, one operating as a generator, the other as a receptor, can be a better way to do these test. Another advantage is the possibility to realize accurate measurements of the different losses in the converters under test. In the first part of this paper, the characteristics of the method concerning loss measurements are compared to those of the electrical or calorimetric methods, then it is shown how it can be applied to different types of power electronic converters, choppers, switched mode power supplies, and pulsewidth modulation inverters. In the second part, different examples of studies conducted by the authors, and using this method, are presented. They have varying goals, from the test of soft-switching inverters to the characterization of integrated gate-commutated thyristor (IGCT) devices mounted into 2-MW choppers. [ABSTRACT FROM AUTHOR]

Power-factor-corrector (PFC) converters are now commonly used in low-power supply systems connected to ac net- works. In addition to their basic PFC properties, they constitute the best technical solution to directly obtain the compatibility with a large range of ac voltages provided by different distribution networks around the world (typically, from 85 to 265 V rms). It is the main application of these converters. This function is achieved with an additional cost and volume, and this extra price to pay needs to be minimized. In this context, we first recall the main approaches of the de- sign of conventional PFCs based on the boostconverter topology. We emphasize the different critical points of the sizing that mainly concern the input choke and the silicon devices, in regard with the choice of the switching frequency. Few ways of improvement are then presented for these conventional PFCs. In a second part, always in the context of a large input voltage range, we consider the possibility to introduce the multi-level concept to reduce the input choke and filters. A solution using a multi-level flying Capacitor Two-Cell converter is presented. It is shown that it can lead to a significant increase of the performances, with several options of sizing which can be suited to different requirements of the applications. [ABSTRACT FROM AUTHOR]

Analyzes the properties of multicell converters. Analysis of the different ways to introduce soft switching in multicell converters; Concept of distributing power over several switches; Description of direct ac-ac converters using the multicell approach.

Examines the consequences of faults in hard-switching and soft-switching multicell converters. Use of different arrangement of components; Differences of consequence of faults; Description of solutions to minimize the consequences of major faults.