This master thesis aim to design and evaluate a high power 3-phase DC/AC and AC/AC converter. The purpose is to use it for an electric motor in an aircraft possibly driving electric actuators, a propeller in an UAV or a small vehicle. Factors such as power loss and weight are of importance and will be estimated using known models supplied by various manufacturers of components. Different topologies of semiconductors suitable for this purpose are examined and presented. Extensive resources have been put to properly select the most suitable switching device according to their power loss and weight. The need for filters and protective circuits will be estimated according to regulations of common military avionic standards and will be included in the resulting estimation along with simulations to evaluate their need and importance. Snubber circuits will be presented and their specific ability to reduce voltage transients and switching losses will be examined along with some simulations to illustrate their performance. In the final part an estimation of efficiency and weight of higher and lower power models of the same inverter has been made using the same procedure as presented in this paper. Engineering rules have been formed from these estimations to simply be able to calculate the proportions of a future converter of arbitrary rated power.

Universiẗat, Diss--Kassel, 2004.

Zugl.: Karlsruhe, Univ., Diss., 2008

Zugl.: Dresden, Techn. Univ., Diss., 2009

Techn. Hochsch., Diss., 2005--Aachen.

abstract: An embedded HVDC system is a dc link with at least two ends being physically connected within a single synchronous ac network. The thesis reviews previous works on embedded HVDC, proposes a dynamic embedded HVDC model by PSCAD program, and compares the transient stability performance among AC, DC and embedded HVDC. The test results indicate that by installing the embedded HVDC, AC network transient stability performance has been largely improved. Therefore the thesis designs a novel frequency control topology for embedded HVDC. According to the dynamic performance test results, when the embedded HVDC system equipped with a frequency control, the system transient stability will be improved further. / Dissertation/Thesis / M.S.Tech Electrical Engineering 2013

No description available.

The totem pole PFC suffers from the Mosfet body diode reverse recovery issue which limits this topology adopted in the CCM high power condition. As the ultra-fast IGBT which is capable of providing 100 kHz switching frequency is available in the market, it is possible to apply the totem pole PFC in CCM high power condition. The thesis provides a method by implementing the ultra-fast IGBT and SiC diode to replace the MOSFET in this topology. To verify the method, a universal CCM totem pole PFC is designed and tested. The design adopts the ADP1048 programmable digital PFC controller by adding external logic gate for totem-pole PFC. ADP1048 greatly simplifies the design process and satisfies the design requirements. The experiment results verify that the totem-pole PFC can be applied into CCM high power condition by using the method. The DC output voltage is well regulated. The power factor is higher than 0.98 when the load is above 400W. The measured efficiency can achieve up to 96.8% at low line and 98.2% at high line condition with switching frequency 80 kHz. / Master of Science

Les transistors IGBT sont les composants semi-conducteurs de puissance les plus couramment utilisés dans les fonctions de l'électronique de puissance. Ils sont fréquemment assemblés dans des modules contenant plusieurs puces et réalisant l'interconnexion à la fois électrique et thermique avec l'environnement. Dans de nombreuses applications, ces modules sont soumis à un cyclage thermique actif généré par les variations du régime de fonctionnement du système. Ceci est à l'origine de différentes dégradations d'origine thermomécaniques pouvant mener à la défaillance. Les tests de vieillissement sont l'un des moyens permettant de mieux comprendre les mécanismes de dégradations en imposant des conditions de stress connues mais également de construire des modèles de fiabilité comportementaux utiles dans l'estimation de durée de vie des systèmes.Le présent travail décrit la mise en œuvre d'une méthode de test originale destinée à des modules IGBT de la gamme 600V-200A et basée sur l'utilisation d'onduleurs fonctionnant en modulation de largeur d'impulsion. Elle exploite la variation de température de jonction provoquée par cette modulation pour générer un cyclage thermique d'une fréquence très supérieure (2Hz à 10Hz) à celles habituellement utilisées pour ce type de test. Ceci permet de réduire considérablement la durée de ces tests et d'accéder à des gammes basses de l'amplitude des cycles thermiques.Les essais de vieillissement imposent de suivre l'évolution de paramètres indicateurs afin d'estimer régulièrement l'état des composants testés et d'appliquer des conditions d'arrêt. Le paramètre utilisé dans le présent travail est la tension VCE des IGBT, qui est un bon révélateur de l'état des fils de bondings, maillons faibles de ces modules. En complément du développement de la méthode de cyclage proprement-dite, un dispositif de suivi automatique du paramètre VCE a été développé afin de limiter la durée des phases de caractérisations correspondantes. Ce dispositif permet également de mesurer la température de jonction de façon indirecte et de reconstruire le profil de température dynamique pendant le cyclage.Cet ensemble a permis d'obtenir des résultats exploitables sur une trentaine d'échantillons avec des amplitudes de cycle comprises entre 30°C et 50°C. Ils mettent en évidence un seul type de dégradation, la fissuration des attaches entre les fils de bonding et la métallisation d'émetteur avec, dans certains cas, le décollement complet du fil (lift-off). Des essais à différentes fréquences de cyclage pour la même amplitude ont été réalisés sur un groupe de ces échantillons. Si le nombre d'échantillons consacrés à comparaison n'est pas encore réellement suffisant, les résultats obtenus sont similaires et semblent donc démontrer que la fréquence de test n'impacte pas le mode de vieillissement dans la gamme de température étudiée. Cette observation est une première validation de la pertinence de la méthode proposée qui permet de réduire d'un facteur cinq à dix les durées de test. / IGBT transistors are the most used power semiconductor devices in power electronics and are often integrated in power modules to constitute basic switching functions. In various applications, IGBT power modules suffer thermal cycling (or power cycling) due to variations of operating conditions. This power cycling induces thermo mechanical stress that can lead to damages and then, to failures. Ageing tests are a means to identify and analyze the degradation mechanisms due to power cycling by imposing calibrated test conditions. In addition, their results can be used to establish empiric lifetime models that are useful for power converter designers.The present work describes the implementation of an ageing test method dedicated to IGBT modules operating in the 600V-200A range. This method takes advantage of particular operating conditions generated by pulse width modulation inverters in which the IGBT modules to be tested are introduced. The modulation induces a variation of IGBT die temperature, i.e. a power cycling, of which the frequency is significantly higher (2Hz to 10Hz) than the operating frequencies of classical test systems. By using this technique, the test length is reduced while low values of thermal amplitude can be reached.Throughout the ageing tests, the monitoring of ageing indicators is required to evaluate the sample health and to stop the operation when predefined conditions are reached. In the present work, the ageing indicator is the on-state voltage VCE across the IGBT device that is relevant in regard with wire bond degradations. Therefore, as a complement of the fast test method, an automated VCE monitoring system has been developed in order to fully take benefit of the high test-speed. In addition, this system is able to measure the junction temperature and to provide the temperature profile during the power cycling.This test bench has made possible the ageing process of three dozen of samples by applying thermal swing amplitudes in the 30°C-50°C range, that is not reachable with classical test benches operating in low frequency because of the unacceptable test length. The results show that only one kind of damage is generated by the present test conditions, i.e. the degradation of attaches between the emitter metallization and the wire bonds. In many case, complete lift-off have been observed. Some samples have been used to evaluate the influence of thermal swing frequency on the results. The latter are unchanged when the frequency varies between 2Hz and 0.2Hz, therefore it is a first validation of the fast test relevance.

This thesis aims to design a cabinet to house some of the required hardware to realize a 1000 A IGBT inverter controlled static excitation system. In the thesis practical design considerations are identified and solved. The suggested excitation system requires a cabinet to house the inverters. Together with inverter requirements stated by the inverter manufacturer and possible electromagnetic interference from switching of the IGBT:s, practical design considerations arise when realizing the system. Identified design considerations are heat dissipation, EMI, IP-code requirements and mechanical stresses at inverter connections. In this study, the design considerations are addressed and a cabinet design with required components inside is suggested. The suggested cabinet together with its components could fulfil the suggested system's- and the inverter's requirements. However, the IP-code allowed by the suggested EMC-seals might be lower than the IP54 required by the inverter. The cabinets EMC-properties will probably be lowered if regular rubber gaskets are used. The study suggests one possible configuration which is possible to realize. It is suggested that further consideration is dedicated to the EMI reducing properties of the cabinet if it is to be installed in an environment sensitive to EMI.