This paper presents a 30kW - 97% efficiency isolated DC-DC converter with fixed (200V or 400V) regulated output voltage and wide range (200V to 600V) input voltage. After theoretical investigations on single stage isolated converters, our main orientation was to design a Dual Active Bridge (DAB) with fixed input and output voltages, to ensure galvanic insulation with very high efficiency. The fixed input voltage of the DAB is provided by an 8-phase interleaved BOOST converter. An original planar transformer structure has been designed for the DAB. Experimental results for the full structure are presented in the article.

Generally, studies on ageing of power module have very often sought to write phenomenological laws able to give an estimate of their lifespan. These laws, identified experimentally, are empirical functions of the characteristic electrical loads that the component must withstand. As an alternative, this paper presents a first attempt of numerical approach for wire bond ageing in semiconductor power modules that takes account for the different multi-physical coupling mechanisms that occur during the component life. The electro-thermal and thermomechanical interactions are physically described and numerically modeled. The calculations show important viscoplastic strains in the connection zones and bonding wires from the first loading cycles. A quasi-cyclic stabilization of the mechanical and thermal states is observed at more than a hundred cycles (viscoplastic shakedown). The creep-fatigue damage mechanisms become then preponderant inducing mechanical-electrical couplings.

Wirebonds ageing in power modules used in electric vehicles is a main concern for the development of reliable inverters. The development of a specific test bench to study the evolution of their properties over time has allowed conclusions to be drawn on the possibility of accelerating or not accelerating ageing tests without distorting the mechanisms actually involved in ageing. Through the use of specifically developed test bench in terms of electrical and thermal properties the studied wirebonds samples are more easily thermally controllable, equipped with measuring devices and the energy consumption at a given cycle is divided by ten compared to a classical bench. The entire process of designing and producing the specific samples and the associated test bench and a description of the first results obtained to demonstrate the relevance of the approach is given.

The paper presents the impact of thermal cycling frequency on the lifetime of IGBT power module. The first part will be devoted to a quick presentation of the test bench. Then, the test protocols will be detailed as well as the measurement protocol to characterise the ageing of the power module wirebonds. An important part will be devoted to the results of ageing. Before concluding, mechanical tensile tests on bondwires will complete the ageing tests.

This paper presents the design of specific samples dedicated to the test of power bond wires (300 µm diameter). The aim is to totally control the test conditions on each bond wire while reducing drastically the power consumption. The samples are integrated in a particular test bench that allows conducting easily ageing tests with an on-line monitoring. The main idea is to solder Power MOSFET dies used as heating sources on an Integrated Metallic Substrate having a high thermal impedance. First, the paper describes the design process, aided by Finite Element simulations. A second part focuses on the realization of the samples and of the test bench. Finally, the first ageing results are presented.

The subject of this paper falls under the development of power electronics for more electric aircraft systems. The study concerns the design of a converter whose function is to generate a 300-V dc bus from a standard 28-V dc avionic network. Various systems, such as motor drives, need to be connected to the 28-V dc network. Their design could be simplified significantly, and standardized, by introducing this intermediate 28-300-V stage. The step-up converter in the proposed configuration is integrated as a part of the system. The power specification is 10 kW, which leads to very high-current values on the 28-V side. The choice of the converter topology, therefore, needs to match this central constraint. The proposed converter uses six boost cells, associated to constitute a series-parallel architecture. This arrangement leads to significantly more optimal sizing for high step-up ratios than conventional boost-cell configurations. Cell interconnection is implemented by means of a monolithic InterCell transformer to reduce the weight of the magnetic part. This paper describes the topology, design, and construction of the lab prototype, as well as experimental results obtained during testing.

The magnetic components represent an important part of the power electronic converters in terms of volume and cost, particularly in switching power supplies. Therefore, it is essential to develop methods and software tools to optimize the magnetic device design in relation with the conversion parameters. To built a design process of magnetic components, it is necessary to identify the constraints induced by the specifications, to choose the electrical conductors and the magnetic cores, both in terms of materials and geometries, to calculate accurately the losses in these two parts and, finally to introduce thermal models in order to determine the temperature reached in the different parts. Indeed, the respect of correct operating temperatures must be the main constraint of any design process, particularly in power systems. In this paper, a generic design tool based on the approach mentioned above and mainly dedicated to high frequency power transformers is presented. For a large part, this tool uses analytical models, and in addition, some steps of the process are realized by mean of Finite Element simulations. Different experimental measurements have been made to verify the model validity, especially concerning thermal features magnetic and complete the content of the paper.

This paper presents new developments of a power cycling test bench targeted to perform very high numbers of cycles at low DeltaTJ (>10(exp 9) cycles, 10 to 20 deg C). This test bench is based on operation of a bridge inverter in which the power devices are the modules to be tested and induces a power cycling of the power dies in realistic conditions (switching), with a high flexibility. This apparatus makes possible carrying out power cycling conventional tests (low frequency, 0.01 Hz to 0.1 Hz) as well as fast tests by using the temperature variation induced by a medium frequency (10 Hz to 100 Hz) load current adjusted by PWM modulation. The test bench is described briefly and the power cycling modes now available are illustrated by thermal measurements carried out on 1200 V - 75 A IGBT modules with an IR camera. Finally, results of ageing tests at low temperature swing (10 deg C and 20 deg C) are presented.

This paper focuses on the study of high-capacitance embedded capacitors for power electronics applications, manufactured by the screen-printing technique. Thick film ferroelectric ceramic was printed on Ag/Al2O3 substrates and dried at 120 °C, then a pre-treatment was applied by cold isostatic pressing (CIP) before sintering. A comparison of the physico-chemical and electrical properties of the non-CIP and CIP samples is made. The results show that the thick film samples pre-treated by CIP have higher permittivity and higher dielectric strength compared to the untreated ones. The capacitor samples with CIP pre-treatment also exhibit higher capacitances, lower parasitic equivalent series inductance and series resistance; all key intrinsic dielectric properties relevant for applications. We propose the use of this process for obtaining the embedded capacitors that allow for high-capacitance values for decoupling and filtering in power electronics applications.

Le choix d'une architecture de convertisseur puis la conception d'un prototype demonstrateur, pour repondre a une specification donnee, reste un exercice difficile dans une jungle topologique et technologique. Le developpement d'outils d'aide a la conception est donc un passage oblige pour faciliter la tâche des concepteurs mais aussi pour optimiser veritablement les solutions. La puissance sans cesse croissante des plates-formes logicielles et des ordinateurs personnels offre un potentiel largement suffisant pour atteindre des objectifs ambitieux dans cette assistance a la conception. Cela dit, de nombreux problemes restent a resoudre et parmi eux, la synthese de modeles realistes et utilisables dans l'optimisation d'un systeme complet n'est pas le moindre. Cette contribution propose une philosophie mixant analyses physiques, formulations empiriques issues de bases de donnees et caracterisations experimentales pour construire les modeles des principaux acteurs des etages de puissance que sont les composants actifs et passifs, associes selon les cas a des vecteurs de refroidissements.

This paper reports on the impact of single event gate rupture and post-irradiation gate stress on Power MOSFETs switching ability. A dedicated setup has been developed and presented in this paper. The data showed that devices can switch after Single Event Gate Rupture. Failure of energy conversion system does not depend on gate current of the device but its associated external circuitry. Moreover, the data showed that devices having a gate layout constituted of parallel stripes are less sensitive than hexagonal shape when electrical constraints are applied after failure. It was also observed that the sensitivity of SEGR can be enhanced by X-ray irradiation but enhanced degradation is not observed during the switching operation.

This paper presents fast test protocols for ageing IGBT modules in power cycling conditions, and a monitoring device that tracks the on-state voltage V-CE and junction temperature T-j IGBTs during ageing test operations. This device is implemented in an ageing test bench described in previous papers, but which has since been modified to perform fast power cycling tests.The fast test protocols described here use the thermal variations imposed on IGBT modules by a test bench operating under Pulse Width Modulation conditions. This test bench reaches the maximal values of power cycling frequencies attainable with a given module packaging in order to optimize test duration.The measurement device monitors V-CE throughout the ageing test that is needed to detect possible degradations of wire bonds and/or emitter metallization. This requires identifying small V-CE variations (a few dozen mV). In addition, the thermal swing amplitude of power cycling must be adjusted to achieve a given ageing protocol. This requires measuring junction temperature evolution on a power cycle, which is carried out by means of V-CE measurement at a low current level (100 mA).Experimental results demonstrate the flexibility of this test bench with respect to various power cycling conditions, as well as the feasibility of the proposed on-line monitoring methods. (C) 2014 Elsevier Ltd. All rights reserved.

This paper deals with the design of high power density DC/DC buck converter for portable bench space charge measurements in full-size HVDC cables. The design of a coupled interleaved buck converter used for delivering the necessary regulated high transient current (up to 1200A during one or two seconds) is presented. The structure is original regarding its compacity and the use of an innovative, small and compact structure of magnetic coupling called InterCell transformer (ICT) which guarantees an excellent filtering of the output current. Experimental results are included in order to confirm the effectiveness and the advantages of the proposed structure. Thermal step current measurements are included in order to validate the application principle on aged power cable loops.

This exploratory work aims to develop and validate a technology of plane substrates close to "Busbar" but directly integrating capacitive layers. These capacitive layers may be used to realize the decoupling capacitor required by any switching cells on its DC bus and/or to realize the capacitors of a common filter placed on the same DC bus. As an additional property, this approach allows matching the shape and the arrangement of the capacitive layers with the building requirements of the full converter. The technological process to achieve that aim is the screen-printing technique. The process was optimized in order to manufacture high electrical performance multilayer ferroelectric ceramic capacitors. High capacitance values density (2,2 divided by 2,7nF/mm(2)), low parasitic losses (ESR<11m Omega; ESL< 3nH), low leakage currents, high dielectric withstand voltage (>300V) are obtained. These new integrated passive components are then used for the realization of planar integrated multilayer capacitive substrate in a practical DC-DC converter.

Recent uninterruptible power supply (UPS) systems, in the medium power range (a few 100 kW), are based on a three-power stage topology including a rectifier, an inverter, and a dc-dc converter. The dc-dc converter ensures the charger/discharger function necessary for battery management. The monolithic intercell transformer (ICT) described in this paper is dedicated to such a charger/discharger, of which the nominal power is 137 kW. This dc-dc converter is comprised of eight interleaved cells that are interconnected by the ICT. The first part of this paper briefly presents the full UPS system and the topology of the eight-cell charger/discharger arranged around the eight-phase monolithic ICT. The second part suggests a model and emphasizes the design specificities of the monolithic ICT. The final design is provided by an optimization routine, checked in the end by different 2-D and 3-D finite-element simulations, both electromagnetic and thermal. The third part describes the construction of the ICT prototype. It is then placed in a test bench that reproduces the conditions of future operations and provides current balance conditions. Finally, the experimental results obtained for the 137-kW nominal power validate design parameters and confirm the interest of the ICT solution.

In Power Electronics (PE), discrete components are generally integrated into distinctive functional modules such as active power modules and passive power modules. This paper aims to study and optimize these last ones, with a special focus on the realization of integrated capacitive components since, among all the passive components used, capacitors usually represent the largest volume and weight. Thanks to the ferroelectric ceramic material used and to an optimized process flow, a reduction in volume and dimension are gradually obtained.

This paper deals with the design of high power density DC/DC buck converter for portable bench space charge measurements in full-size HVDC cables. The design of a coupled interleaved buck converter used for delivering the necessary regulated high transient current (up to 1200A during one or two seconds) is presented. The structure is original regarding its compacity and the use of an innovative, small and compact structure of magnetic coupling called InterCell transformer (ICT) which guarantees an excellent filtering of the output current. Experimental results are included in order to confirm the effectiveness and the advantages of the proposed structure. Thermal step current measurements are included in order to validate the application principle on aged power cable loops.

This paper describes a part of a larger supervision system able to monitor the on-state voltage VCE and the junction temperature TJ of IGBT in operation. That system is associated to an ageing test bench stressing IGBT modules by power cycling. All along the ageing test, it is necessary to supervise VCE, always measured in the same conditions of junction temperature and collector current, in order to detect possible degradations of wire bonds and/or emitter metallization. In addition, the thermal swing amplitude of the power cycling must be adjusted to realize a given ageing protocol. That requires measuring the junction temperature evolution on a power cycle to choose the initial electrical conditions providing the wished temperature swing and then, to regularly verify the stability of this thermal stress during the ageing test. The temperature measurement needed for both monitoring is carried out by means of VCE measurement at low current level (100mA), that intrinsic on-stage voltage being a well-known thermo sensitive parameter. The first section describes briefly the ageing test bench, that places the power IGBT modules in operating conditions close to those of real world (PWM operations), and presents the thermal stress protocol applied to the devices, the aim being to define the context in which the measurements have to be made. The second section presents, on the one hand, the principle of an automated measurement of VCE(100A-125°C), made in steady-state, to detect a possible degradation of the top part of IGBT dies, on the other hand, the dynamic measurement of the junction temperature in operation, i.e. in power cycling conditions generated by the PWM modulation. In both cases, experimental results are shown that demonstrate the feasibility and the good accuracy of these monitoring methods.

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.