Actuellement, la majorité des convertisseurs embarqués dans des trains circulant sous une caténaire alternative est composée d’un transformateur basse fréquence, puis de redresseurs,alimentant des moteurs de traction via des onduleurs de traction. Les inconvénients majeurs de ces structures sont un volume et une masse embarqués importants, dus au transformateur fonctionnant en basse fréquence. Le rendement est également mauvais, à cause des contraintes de volume et de masse. Grâce aux développements des semiconducteurs haute tension et forte puissance et des transformateurs moyenne fréquence, i.e. de l’ordre de quelques kilohertz, de nouvelles topologies de convertisseurs embarqués, appelées transformateurs électroniques, sont à l’étude. Si plusieurs topologies ont déjà été étudiées dans la littérature, elles n’ont jamais été comparées. L’objectif principal de cette thèse est donc de proposer une méthodologie de dimensionnement des différentes topologies de transformateurs électroniques, afin de pouvoir les comparer. Un état de l’art des différentes structures proposées dans la littérature est présenté dans le premier chapitre de ce mémoire. Le chapitre 2 est consacré à la comparaison de structures indirectes. Pour cela, une méthodologie, permettant d’optimiser le dimensionnement de chaque structure afin de maximiser son rendement sous des contraintes de masse et de volume, a été développée. Elle est ensuite appliquée sur des topologies utilisant des MOSFET SiC, contrairement aux structures à IGBT Si développées dans la littérature. L’inductance magnétisante est considérée afin d’assurer un fonctionnement en commutation douce, et ainsi limiter les pertes. Un troisième chapitre propose un filtre actif innovant, intégré aux DC-DC du convertisseur. Celui-ci a pour but de réduire le volume du condensateur de filtrage des bus intermédiaires, et ainsi le volume total du convertisseur, sans dégrader la fiabilité intrinsèque de celui-ci. Son fonctionnement et son impact sur les pertes du DC-DC y sont étudiés. Enfin, le dernier chapitre est dédié à l’étude des interactions entre le convertisseur embarqué et l’infrastructure ferroviaire. Pour cela, des modèles d’infrastructure 25 kV-50 Hz ont été réalisés. Ceux ci comportent notamment un circuit original modélisant l’effet de peau dans la caténaire. Des résonances à certaines fréquences, caractéristiques de la géométrie du réseau et de la position du train sur celui-ci, ont été mises en évidence dans l’impédance vue par le train. Ces modèles ont aussi été implémentés dans un simulateur numérique, pour alimenter une maquette petite échelle de convertisseur. Ce type de test n’a, a priori, jamais été réalisé sur un transformateur électronique. Une conclusion générale et des perspectives sur les travaux présentés concluent ce mémoire / Current on-board converters, running on AC catenaries, are mainly composed by a low frequency transformer, then rectifiers, supplying traction motors through three-phase inverters. Due to volume and mass constraints on the converter, the efficiency of the transformer is limited. Moreover, this transformer is quite bulky and heavy. Thanks to the development of high voltage and high power semiconductors, such as Si IGBTs or SiC MOSFETs, and of medium frequency transformer, i.e. operating at a few kilohertz, new topologies of on-board converters, named Power Electronic Traction Transformer (PETT), are studied. Though several structures have been studied in the literature, they have never been compared. The main objective of this thesis is, thus, to develop a methodology to size PETT topologies, in order to compare them. In the first chapter, a state of the art of the PETT structures proposed in literature is presented. The second chapter is dedicated to the comparison of indirect topologies. A methodology, optimising the sizing of each structure to maximise its efficiency under mass and volume constraints, is developed. It is applied on topologies using SiC MOSFETs, contrary to Si IGBT structures developed in the literature. The magnetizing inductance is also considered to insure soft switching and reduce the losses. In the third chapter, an novel active filter, included in the DC-DCs of the converter, is proposed. The aim is to reduce the volume of the filtering capacitors on the intermediate buses, and thus, of the entire converter, without impacting the intrinsic reliability of the converter. Its impact on the losses of the DC-DC is studied. The last chapter deals with the interactions between the on-board converter and the infrastructure. Thus, the 25 kV-50 Hz railway network is modeled. It includes a novel circuit, modelling the skin effect in the catenary. Some resonances, dependant on the sector geometry and the train position, are highlighted in the impedance seen by a train. Moreover, the models are implemented in a numerical simulator to supply a small scale mock-up of a PETT. PHIL tests have, a priori, never been carried on a PETT. A conclusion and some perspectives of future work close thisdissertation.

No description available.

This paper describes the design, fabrication, and testing of a 1.2 kV, 6.5 mΩ, half-bridge, SiC MOSFET power module to evaluate the impact of parametric device tolerances on electrical and thermal performance. Paralleling power devices increases current handling capability for the same bus voltage. However, inherent parametric differences among dies leads to unbalanced current sharing causing overstress and overheating. In this design, a symmetrical DBC layout is utilized to balance parasitic inductances in the current pathways of paralleled dies to isolate the impact of parametric tolerances. In addition, the paper investigates the benefits of flexible PCB in place of wire bonds for the gate loop interconnection to reduce and minimize the gate loop inductance. The balanced modules have dies with similar threshold voltages while the unbalanced modules have dies with unbalanced threshold voltages to force unbalanced current sharing. The modules were placed into a clamped inductive DPT and a continuous, boost converter. Rogowski coils looped under the wire bonds of the bottom switch dies to observe current behavior. Four modules performed continuously for least 10 minutes at 200 V, 37.6 A input, at 30 kHz with 50% duty cycle. The modules could not perform for multiple minutes at 250 V with 47.7 A (23 A/die). The energy loss differential for a ~17% difference in threshold voltage ranged from 4.52% (~10 µJ) to -30.9% (~30 µJ). The energy loss differential for a ~0.5% difference in V_th ranged from -2.26% (~8 µJ) to 5.66% (~10 µJ). The loss differential was dependent on whether current unbalance due to on-state resistance compensated current unbalance due to threshold voltage. While device parametric tolerances are inherent, if the higher threshold voltage devices can be paired with devices that have higher on-state resistance, the overall loss differential may perform similarly to well-matched dies. Lastly, the most consistently performing unbalanced module with 17.7% difference in V_th had 119.9 µJ more energy loss and was 22.2°C hotter during continuous testing than the most consistently performing balanced module with 0.6% difference inV_th. / Master of Science / This paper describes the design, construction, and testing of advanced power devices for use in electric vehicles. Power devices are necessary to supply electricity to different parts of the vehicle; for example, energy is stored in a battery as direct current (DC) power, but the motor requires alternating current (AC) power. Therefore, power electronics can alter the energy to be delivered as DC or AC. In order to carry more power, multiple devices can be used together just as 10 people can carry more weight than 1 person. However, because the devices are not perfect, there can be slight differences in the performance of one device to another. One device may have to carry more current than another device which could cause failure earlier than intended. In this research project, multiple power devices were placed into a package, or "module." In a control module, the devices were selected with similar properties to one another. In an experimental module, the devices were selected with properties very different from one another. It was determined that the when the devices were 17.7% difference, there was 119.9 µJ more energy loss and it was 22.2°C hotter than when the difference was only 0.6%. However, the severity of the difference was dependent on how multiple device characteristics interacted with one another. It may be possible to compensate some of the impact of device differences in one characteristic with opposing differences in another device characteristic.

The falling cost of batteries, along with an increasing need to cut emissions, has spurred significant interest in the electrification of vehicles. In addition, as semiconductor devices have evolved, the research for electric vehicles with higher battery voltage has increased. The traction inverter is an important part of the electric power train and can account for a substantial portion of the drive train’s losses. This thesis therefore models, simulates, and studies the losses for a convectional Two-Level (2L) inverter and a Three-Level T-Type (3LT) inverter utilizing Silicon Carbide (SiC) MOSFETs and compares the two inverter topologies in terms of efficiency. The rated power of the inverters is 120 kW at a DC voltage of 800 V. The theoretical basis of SiC MOSFET and its reverse conduction, operation of 2L and 3LT inverter topologies, and Space Vector Pulse Width Modulation (SVPWM) technique are introduced in the initial part of the thesis. To estimate switching and conduction losses, Simulink is used to model and simulate an electric drive system. These estimated losses are then utilized to develop efficiency maps for both topologies over the complete speed-torque range. Based on the efficiency comparison, the 3LT topology outperforms the 2L topology for any requested torque in the medium to the high-speed range, which is typical of highway driving. In the low-speed, high-torque region, which is typical of city driving, the 2L topology is superior. The efficiency of each topology is affected by switching frequency, device junction temperature, and DC-link voltage. However, the comparison reveals that the maximum average difference in efficiency is 0.35%, with the 3LT topology being superior. Finally, the efficiency differences between the two inverter topologies are minimal. As a result, it may be concluded that the two topologies perform similarly. Thus, it can be inferred that comparing the efficiency of the two topologies should not be the sole criterion for selecting which topology should be used for the electric drive. / Den sjunkande kostnaden för batterier, tillsammans med ett ökande behov av att minska utsläppen, har lett till ett stort intresse för elektrifiering av fordon. Dessutom, har utvecklingen av halvledare lett till en ökning inom forskningen av elfordon med högre batterispänning. Traktionsomriktaren är en viktig del av den elektriska drivlinan och kan stå för en stor del av de totala förlusterna i drivlinan. I denna rapport modelleras, simuleras och studeras därför förlusterna i en konventionell omriktare med två nivåer (2L) och en T-typ omriktare med tre nivåer (3LT). Båda topologierna använder kiselkarbid (SiC) MOSFETs i jämförelsen av resultaten med avseende på verkningsgrad. Inverterarnas nominella effekt är 120 kW vid en likspänning på 800 V. Den teoretiska grunden för SiC MOSFET och hur de fungerar, hur 2L- och 3LT-inverterstopologierna fungerar samt tekniken för Space Vector Pulse Width Modulation (SVPWM) presenteras i rapporten. För att uppskatta switch- och ledningsförluster används Simulink för att modellera och simulera det elektriska drivsystemet. De uppskattade förlusterna används sedan för att utveckla verkningsgradskartor för de båda topologierna över hela det operativa området. Baserat på verkningsgradsjämförelsen mellan topologierna så presterar 3LT-topologin bättre än 2L-topologin i driftspunkter i medelhöga till höga hastigheter, vilket är typiskt för motorvägskörning. Vid låga hastigheter med högt vridmoment, vilket är typiskt för stadskörning, är 2L-topologin bättre. Verkningsgraden för de båda topologierna påverkas av switchfrekvensen, halvledarens temperatur samt DC-länkspänning. Jämförelsen visar dock att den största genomsnittliga skillnaden i verkningsgrad mellan de två topologierna är 0,35%, där 3LT-topologin är bättre. Sammanfattningsvis så är skillnaderna i verkningsgrad mellan de två topologierna minimala, vilket innebär att de båda topologierna har liknande prestanda med avseende på verkningsgrad. Man bör därför inte bara ha verkningsgrad som det enda kriteriet vid val av topologi för elektriska drivlinor.

The swift shift of the automotive industry towards electrification is primarily propelled by technological advancements in battery technology. To stay competitive and meet the new demands of the industry, there is a crucial need for novel ideas and innovation. Higher energy density and lower cost makes Battery Electric Vehicles (BEV) competitive and affordable for a wider range of customers. Component space requirements inside a BEV as well as the growing trend towards increasing the voltage of the system from 400 V to 800 V poses new challenges that has to be overcome. Mechanical contactors have the advantage of being simple and easy to use, with low conductive losses. However, they have some drawbacks, such as poor performance when switching under load, limitedability to interrupt fault currents and large controlpower usage. To address these issues, a bidirectional MOSFET configuration can be used to replace the current system. This configuration provides enhanced abilities to quickly suppress fault current, improve robustness, eliminate mechanical failure points, and perform pre-charge sequences without the need for a dedicated branch. Additionally, this configuration maintains current performance in a smaller volume. Within the Battery distribution unit (BDU), this configuration replaces several components, such as thermal fuses, HV contactors, pre-charge relays,pre-charge resistors, and breaker/pyro-fuses with high voltage solid-state components. This study aims to propose potential mitigation methods through a combination of literature survey and comprehensive analysis using Simscape/-MATLAB Simulink models of a fully operational BDU utilizing readily available market components for a 1.2 kV system. The developed model illustrates the thermaland electrical performance of solid-state components in diverse testing scenarios, while maintaining their expected lifecycle. Additionally, sensitivity analysis is conducted using the proposed model to identify themost crucial design parameters within the system. The resulting system performs satisfactory during normal operations, albeit with ten times higher conductive losses attributed to the elevated junction resistance when compared to contactors.Consequently, additional cooling measures are required during harsh operations and DC fast charge. However, the required magnitization energy for a contactor does over time equate or even surpass the MOSFETs conductive losses. The design has established the feasibility of leveraging the primary switchfor pre-charge sequence execution, thus eliminating the need for a dedicated pre-charge branch. The system exhibits strong potential for interrupting both resistive and direct shorts at various locations in the model. However, the low system inductance and the need to avoid introducing any additional inductance into the system renders fault scenarios heavily dependent on said parameter. In conclusion, the proposed model exhibits considerable potential to eliminate numerous auxiliary components therefore reducing losses and offer a more adaptable and consolidated solution. Resulting in a smaller physical footprint and more favorable positioning within the BDU. Moreover, the financial analysis of the system highlights promising prospects for its integration into the drivetrain with the growingmarket trends.

The intentions of the so-called "More Electrical Aircraft" (MEA) are higher efficiency and lower weight. A main topic here is the application of electrical instead of hydraulical, pneumatical and mechanical systems. The necessary power electronic devices have intermediate DC-links, which are typically supplied by a three-phase system with active B6 and passive B12 rectifiers. A possible alternative is the B6 diode bridge in combination with an active power filter (APF). Due to the parallel arrangement, the APF offers a higher power density and is able to compensate for harmonics from several devices. The use of the diode bridge rectifier alone is not permitted due to the highly distorted phase current. The following investigations are dealing with the development of an active power filter for a three-phase supply with variable frequency from 360 to 800 Hz. All relevant components such as inductors, EMC-filters, power modules and DC-link capacitor are designed. A particular focus is put on the customized power module with SiC-MOSFETs and SiC-diodes, which is characterized electrically and thermally. The maximum supply frequency slope has a value of 50 Hz/ms, which requires a high dynamic and robustness on the control algorithm. Furthermore, the content of 5th and 7th harmonics must be reduced to less than 2 %, which demands a high accuracy. To cope with both requirements, a two-stage filter algorithm is developed and implemented in two independent signal processors. Simulations and laboratory experiments confirm the performance and robustness of the control algorithm. This work comprehensively presents the design of aerospace rectifiers. The results were published in conferences and patents. / Hauptziele des sogenannten "More Electrical Aircraft" (MEA) sind Effizienzerhöhung und Gewichtseinsparung. Ein Schwerpunkt hierbei ist die Nutzung von elektrischen statt hydraulischen, pneumatischen und mechanischen Systemen. Die notwendigen Leistungselektroniken haben DC-Zwischenkreise, welche mittels aktiven B6 und passiven B12 Gleichrichtern aus dem Dreiphasennetz gespeist werden. Eine mögliche Alternative ist die B6 Diodenbrücke in Kombination mit einem aktiven Netzfilter, welcher aufgrund der parallelen Anordnung eine höhere Leistungsdichte aufweist und darüber hinaus mehrere Geräte gleichzeitig entstören kann. Die alleinige Nutzung einer Diodenbrücke ist aufgrund des hohen Anteils von Stromharmonischen nicht zulässig. Diese Arbeit beschäftigt sich mit der Entwicklung eines aktiven Filters für ein Dreiphasensystem mit variabler Frequenz von 360 bis 800 Hz. Es werden alle relevanten Bauteile wie Induktivitäten, EMV-Filter, Leistungsmodule und Zwischenkreiskondensator ausgelegt. Besonderes Augenmerk liegt auf dem kundenspezifischen Modul mit SiC-Dioden und SiCMOSFETs, welches vollständig elektrisch und thermisch charakterisiert wird. Die Änderung der Netzfrequenz beträgt bis zu 50 Hz/ms, was eine hohe Dynamik und Robustheit von der Filterregelung verlangt. Weiterhin ist im statischen Fall eine hohe Genauigkeit gefordert, da die 5. und 7. Harmonische auf unter 2% geregelt werden müssen. Um beiden Anforderungen gerecht zu werden, wird ein zweistufiger Regelungsalgorithmus entwickelt der auf zwei digitalen Signalprozessoren implementiert wird. Simulationen und Labormessungen bestätigen die Robustheit des Regelungskonzeptes. Diese Arbeit stellt umfassend die Entwicklung von Luftfahrtgleichrichtern dar. Die Ergebnisse wurden in Konferenzen und Patenten veröffentlicht.

Les MOSFET en SiC sont appelées à remplacer les IGBT en Silicium pour des applications de demandant une plus forte vitesse de commutation. Cependant, les MOSFET en SiC ont encore quelques problèmes de fiabilité, tels que la robustesse de la diode interne ou bien la robustesse de l'oxyde de grille. Cette dernière est liée à l’oxyde de grille des composants du type MOSFET. Des instabilités de la tension de seuil sont aussi signalées. Cette thèse aborde ces deux sujets sur des MOSFET commerciaux 1200 V. L'étude de la diode interne met en évidence que les caractéristiques I-V (de la diode intrinsèque) demeurent stables après l'application d'un stress. Cependant, une dérive surprenante de la tension de seuil apparaît. Des tests complémentaires, en stressant le canal à la place de la diode, avec les mêmes contraintes n'ont pas montré de dérive significative de la tension de seuil. Donc, l'application d'un stress en courant quand le composant est en mode d'accumulation semble favoriser l'apparition des instabilités de la tension de seuil. La robustesse de l'oxyde de grille concerne les instabilités de la tension de seuil, mais aussi l'estimation de la durée de vie à des conditions d'opération nominales. Les résultats obtenus montrent que la durée de vie de l'oxyde de grille n'est plus un problème. Pourtant, le suivi du courant de grille pendant les tests ainsi que les caractérisations de la capacité de grille mettent en évidence des translations de la courbe C(V) à cause des phénomènes d’injection des porteurs et de piégeage, mais aussi la possible présence d’ions mobiles. Aussi, une bonne analyse des dégradations et dérives liées à l’oxyde de grille doit être réalisée. / SiC power MOSFETs are called to replace Si IGBT for some medium and high power applications (hundreds of kVA). However, even if crystallographic defects have been drastically reduced, SiC MOSFETs are always concerned by some robustness issues such as the internal diode robustness or the robustness of the gate oxide. The last one especially affects MOSFETs devices and is linked to the apparition of instabilities in the threshold voltage. This thesis focuses on these two issues. The study of the internal diode robustness highlighted that the I-V curve (of the intrinsic diode) remains stable after the application of a current stress in static mode, but also with the DUT placed in a converter with inductive switchings. These are the most stressful conditions. However, a surprising drift in the threshold voltage has been observed when some devices operates under these conditions; in static mode or in a converter. Complementary tests stressing the channel instead of the internal diode in the same temperature and dissipated power, have not resulted in a drift of the threshold voltage. Thus, the application of a current stress when the device is in accumulation regime could favour the apparition of instabilities in the threshold voltage. The study of the gate oxide focus in the instabilities of the threshold voltage, but also on the expected lifetime of the oxide at nominal conditions. Results obtained shown that the expected lifetime (TDDB) of the oxide is no longer a problem. Indeed, tests realized in static mode, but also in a converter under inductive switching conditions resulted in expected lifetimes well above 100 years. However, the monitoring of the gate current during the test and gate capacitance characterizations C(V) highlighted a shift in the capacitance due to carrier injection and trapping phenomena and probably to the presence of mobile-ions. Still regarding the instabilities of the threshold voltage, classic tests resulted in no significant variations of the threshold voltage at 150 _C. However, at 200 _C the drift observed for some manufacturers is higher than +30%. This is unacceptable for high-temperature applications and evidence that the quality of the gate oxide and the SiC=SiO2 interface must continue to be improved, together with the manufacturing methods to minimize the presence of mobile ions in the substrate.

This thesis deals with switched mode power supplies based on resonant principle to achieve high efficiency. Several ways of switched mode power supplies optimalisation are described as part of the work to achieve better efficiency. Priparily, the new generation of switching elements based on SiC and resonant topology are used to achieve significant switching loss minimization. The selected resonant topology is simualted in detail and then built with focus on high efficiency. The main content of the work consists in the design and realization of the switched mode power supply with selected control algorithms and their comparison. The problems associated with usage of new SiC MOSFET generation in TO-247-4L package are being solved within the design and implementation of the power source. To solve the main problems, new 3rd SiC MOSFET gate driver was developer for working with switching frequencies in hundreds of kHz and resisting very high voltage stress on the controlled transistor. The next part of the gate driver is the overcurrent protection. The overcurrent limit can be set easily by changing one component. This protection reacts very quickly in hundreds of nanoseconds, so it is capable of saving the converter even in branch failure and going to hard short circuit. The functional sample of the series resonant converter was built and revated in the work. The converter based on 3. Generation of SiC MOSFET transistors from Cree in a modern case TO-247-4L was built. For this inverter, it was also necessary to develop both the control scheme and the resonance frequency tracking to achieve accurate switching and thus achieve the use of the resonant principle of the converter to the maximum extent possible. The result of this work is up to 3 kW converter with adjustable output voltage while maintaining high efficiency up to 96%.

The intentions of the so-called "More Electrical Aircraft" (MEA) are higher efficiency and lower weight. A main topic here is the application of electrical instead of hydraulical, pneumatical and mechanical systems. The necessary power electronic devices have intermediate DC-links, which are typically supplied by a three-phase system with active B6 and passive B12 rectifiers. A possible alternative is the B6 diode bridge in combination with an active power filter (APF). Due to the parallel arrangement, the APF offers a higher power density and is able to compensate for harmonics from several devices. The use of the diode bridge rectifier alone is not permitted due to the highly distorted phase current. The following investigations are dealing with the development of an active power filter for a three-phase supply with variable frequency from 360 to 800 Hz. All relevant components such as inductors, EMC-filters, power modules and DC-link capacitor are designed. A particular focus is put on the customized power module with SiC-MOSFETs and SiC-diodes, which is characterized electrically and thermally. The maximum supply frequency slope has a value of 50 Hz/ms, which requires a high dynamic and robustness on the control algorithm. Furthermore, the content of 5th and 7th harmonics must be reduced to less than 2 %, which demands a high accuracy. To cope with both requirements, a two-stage filter algorithm is developed and implemented in two independent signal processors. Simulations and laboratory experiments confirm the performance and robustness of the control algorithm. This work comprehensively presents the design of aerospace rectifiers. The results were published in conferences and patents. / Hauptziele des sogenannten "More Electrical Aircraft" (MEA) sind Effizienzerhöhung und Gewichtseinsparung. Ein Schwerpunkt hierbei ist die Nutzung von elektrischen statt hydraulischen, pneumatischen und mechanischen Systemen. Die notwendigen Leistungselektroniken haben DC-Zwischenkreise, welche mittels aktiven B6 und passiven B12 Gleichrichtern aus dem Dreiphasennetz gespeist werden. Eine mögliche Alternative ist die B6 Diodenbrücke in Kombination mit einem aktiven Netzfilter, welcher aufgrund der parallelen Anordnung eine höhere Leistungsdichte aufweist und darüber hinaus mehrere Geräte gleichzeitig entstören kann. Die alleinige Nutzung einer Diodenbrücke ist aufgrund des hohen Anteils von Stromharmonischen nicht zulässig. Diese Arbeit beschäftigt sich mit der Entwicklung eines aktiven Filters für ein Dreiphasensystem mit variabler Frequenz von 360 bis 800 Hz. Es werden alle relevanten Bauteile wie Induktivitäten, EMV-Filter, Leistungsmodule und Zwischenkreiskondensator ausgelegt. Besonderes Augenmerk liegt auf dem kundenspezifischen Modul mit SiC-Dioden und SiCMOSFETs, welches vollständig elektrisch und thermisch charakterisiert wird. Die Änderung der Netzfrequenz beträgt bis zu 50 Hz/ms, was eine hohe Dynamik und Robustheit von der Filterregelung verlangt. Weiterhin ist im statischen Fall eine hohe Genauigkeit gefordert, da die 5. und 7. Harmonische auf unter 2% geregelt werden müssen. Um beiden Anforderungen gerecht zu werden, wird ein zweistufiger Regelungsalgorithmus entwickelt der auf zwei digitalen Signalprozessoren implementiert wird. Simulationen und Labormessungen bestätigen die Robustheit des Regelungskonzeptes. Diese Arbeit stellt umfassend die Entwicklung von Luftfahrtgleichrichtern dar. Die Ergebnisse wurden in Konferenzen und Patenten veröffentlicht.