Insulated Gate Bipolar Transistors (IGBTs) are popular power electronic switching devices with several advantages. However, they have been known to fail in the field when subjected to significant variations in power dissipation – known as power cycling. In the work presented here, a novel alternating-current (AC) power cycling test method for IGBTs together with their free-wheeling diodes is proposed and verified. A review of previous work revealed that the parameter that most affects IGBT lifetime under power cycling conditions is the variation in its junction-case temperature difference. Through simulation, the behaviour of a conventional single phase inverter (H-bridge) using simple pulse width modulation (PWM) control was quantified, and the effect of switching frequency and load power factor was studied. Results of the simulations and literature review were used to develop design criteria for a new AC test circuit. The new AC test circuit (a modified version of the conventional H-bridge) was then designed and its performance compared to the criteria and to the simulation results of the conventional circuit. The circuit was then built and its performance was validated. The circuit complied with the performance criteria, in particular the desired variation in 7jc, to an adequate degree of accuracy. The proposed test circuit is novel for several reasons. The stresses on devices used in a conventional H-bridge using a high power factor inductive load are reproduced using a low power factor inductive load, considerably reducing the energy cost of running such a test. IGBT switching losses are not actively reduced, as is normal practice, but instead are actively increased to generate the required losses. Free-wheeling diodes are also tested, but do not have significant switching losses, as the nature of the test circuit dictates that these be transferred to the IGBTs. The main drawback of the proposed test circuit is that a larger number of devices are needed; however, this tradeoff is necessary to obtain the energy cost savings provided by this circuit.

Leistungshalbleiter werden in Windenergieanlagen, Elektroautomobilen und vielen anderen Applikationen eingesetzt, bei denen die elektrische Energie in eine spezielle Form zu wandeln ist, um etwa Netzeinspeisung bei Windenergieanlagen oder eine spezifische Beschleunigung bei Elektroautomobilen zu realisieren. Bei ihrem Einsatz altern sie, dabei spielen Lastwechsel eine besondere Rolle. Es wird untersucht, welche Aspekte eine wichtige Rolle bei der Lastwechselbelastung einnehmen, wie sie zu berechnen und zu berücksichtigen sind. Am Beispiel von Leistungsmessdaten zweier an der mittelnorwegischen Küste betriebenen Windenergieanlagen wird beispielhaft gezeigt, wie die Lastwechselbelastung ermittelt werden kann. Im Rahmen der Arbeit wurde ein modularer 2000A Lastwechseltester entwickelt, gebaut und in Betrieb genommen, der mit einer neuen VCE(T) Kalibriermethode, der Aktiven Kalibrierung, ausgerüstet ist. Tester und Kalibriervorgang werden vorgestellt und im Detail diskutiert. Auf dieser Basis werden Perspektiven aufgezeigt, wie Lastwechseltester zukünftig optimiert gestaltet und die Messmethoden zur Alterungsbestimmung in die Applikation überführt werden können. / Power semiconductors are deployed in wind mills, electrical cars and many other applications whenever electrical energy has to be transformed into an intended form e.g. to feed-in wind energy or to accelerate a car. In use they fatigue at which power cycles play an important role. This work investigates the aspects taking the main role at power-cycle load, how they are to calculate and how to be considered. Based on power measurements of two wind mills placed at the middle Norwegian coast, it is shown how to determine the power cycle load. A modular 2000A power cycling test equipment has been developed, built-up and run-in. By means of this equipment a new VCE(T) calibration-method is demonstrated. The equipment as well as the calibration procedure is presented and discussed in detail. On that basis perspectives are depicted how power cycle equipment can be optimized and, moreover, methods for fatigue determination can be transferred from laboratory into application.

Electrical machines have been widely used along the last decades with large life length under operating conditions. However, they will become more important in the upcoming years because of the emerging electric car industry. Thus, the maintenance cost of this technology can be reduced by extending the lifetime in the electrical machines. Despite the fact that existing numerous studies within the life length in these devices, only few study the effect of the thermomechanical stresses of insulation. The core of this master thesis is to study the influence of these stresses in the insulation material of a winding. The tested electrical machines were subjected to different test conditions, allowing to analyse multiple aging effects in the winding. To achieve these effects, power cycling tests were carried out on stators, where the windings were tested in cycles with different ΔT and two cooling methods: air cooling and oil cooling. The results showed large aging differences between the two cooling methods employed. The aging effect in the oil cooling method was higher than in the air cooling method for the same number of cycles. However, the aging effects regarding the same cooling process had not wide differences between the different test temperatures.

No description available.

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.

Cette thèse a pour objet l'étude de la fiabilité de modules de puissance triphasés à IGBTs 200 A - 600 V, destinés à la construction d'onduleurs de traction pour des applications automobiles hybrides ou électriques. Ces travaux visent à évaluer la tenue de ces modules de puissance en régime de cyclage thermique actif à hautes température, en mettant l'accent sur leur résistance à la fatigue thermomécanique. Deux approches complémentaires ont été mises en oeuvre dans ce but: tests de vieillissement accéléré et modélisation numérique. Une compagne d'essais de vieillissement par cyclage actif a été menée avec des profils de température variés, définis par la température ambiante et la variation de température de jonction des IGBTs, utilisés comme facteurs d'accélération des contraintes. Au cours de ces tests, les composants ont électriquement fonctionné dans des conditions semblables à une application réelle (commande MLI). L'objectif était d'identifier les modes de défaillance, d'estimer l'influence des facteurs d'accélération du vieillissement, et d'évaluer la pertinence des indicateurs de défaillance classiques dans ces conditions de stress thermiques sévères. Aussi, afin de mieux comprendre les mécanismes de défaillance responsables de la fatigue de l'assemblage des modules considérés, une modélisation thermomécanique visant à déterminer l'impact des modèles de comportement mécanique sur la durée de vie estimée des brasures, a été développée. La réponse de l'assemblage à des contraintes de cyclage actif similaires à celles appliquées durant les essais a été évaluée par analyse numérique. Les différentes lois de comportement ont été comparées en termes de contraintes, déformations plastiques, et densité d'énergie plastique dans les brasures. / This thesis is dedicated to reliability investigations led on three-phase 200~A~--~600~V IGBT power modules, designed for building drive inverters for hybrid or electric automotive traction applications. The objective was to evaluate the durability of the studied modules when they withstand power cycling in high temperature environments, and especially their resistance to thermo-mechanical fatigue. Two complementary approaches were considered: accelerated aging experiments and numerical modeling.A series of power cycling tests was carried out over a large range of temperature profiles, defined by the ambient temperature and IGBT junction temperature excursion. These quantities are used as thermal stress acceleration factors. Those experiments were led in realistic electrical conditions (PWM control scheme). They aimed at identifying the failure modes of the target devices, assessing the impact of the acceleration factors on their aging process, and evaluating the suitability of standard aging indicators as damage precursors in such harsh loading conditions. Besides, to better understand the failure mechanisms governing the fatigue life of the modules assembly, a thermo-mechanical modeling focusing on solder joints was built. Our simulation efforts concentrated on the appraisal of constitutive modeling effects on solder joints lifetime estimation. Numerical analysis of the assembly response to power cycling in similar operating conditions as practiced in experiments were performed. Behavior laws were then compared on stress, plastic strain, and strain energy density developed within the joints.

This paper deals with a method to additionally heat with switching losses in a classical power cycling test, as it is often used for power semiconductors.The fundamentals of testing, switching behavior, thermal and electrical characteristics of semiconductors are covered.The core of the work is the construction, start-up and solution of technical problems during the testing of the test stand. Another aspects are the measurement and software challenges in generating the pulse pattern and in evaluating the results. The last part of the work deals with the testing of different types of semiconductors, such as IGBTs and MOSFETs, which were also made of different materials, such as silicon and silicon carbide, and had different voltage classes.:Contents i Symbols and Abbreviations iii Introduction 1 1. Power Cycling Lifetime 2 1.1. Power Cycling-induced Ageing Mechanisms and Test Methods 2 1.1.1. Overview of Packaging Technologies and their Wear-out Failures 2 1.1.2. Failure Mechanisms in Power Modules and Discrete Devices 6 1.1.3. Basic Structure of a Test Bench for DC Power Cycling Tests 8 1.1.4. Modifications for SiC MOSFET Operation 12 1.1.5. Measurement Accuracy, Limits and Consequences for Test Evaluation 16 1.1.6. Thermal Resistance and Thermal Impedance Spectroscopy 18 1.2. Empirical Power Cycling Lifetime Models 21 2. Specific Limitations in Conditions for some Devices 27 3. Approaches of an Application-close Power Cycling Test 30 4. New Test Bench Concept with an adjustable part of switching losses 35 4.1. Basics for Switching 35 4.1.1. Active Clamping 38 4.1.2. Boosted Active Clamping 40 4.2. Repetitive Unclamped Inductive Switching 42 4.3. Test Bench Concept for Power Cycling Test with Turn-off Losses 44 4.4. Dimensioning of the Stray Inductance 47 4.4.1. Current Ripple and Attainable Switching Losses 51 4.5. Special Setup for Si and SiC MOSFETs 57 4.6. Measurement Algorithm and necessary Hardware 58 4.6.1. Measurement Hardware 58 4.6.2. Measurement Algorithm 60 4.6.3. Challenges during the Measurement 62 4.6.4. Current Source for Fast Regulation 66 5. Test Results with IGBTs 69 5.1. Modules with Baseplate 69 5.2. Modules without Baseplate 80 5.3. IGBTs in Discrete Housings 90 6. Test Results with MOSFETs 97 6.1. Low Voltage Si MOSFETs 97 6.2. SiC MOSFETs 106 7. Analysis of Si Low-voltage MOSFETs Results with FEM 107 8. Conclusion and Outlook 113 9. Acknowledgement 118 References 119 Appendix 136

Leistungshalbleiter werden in Windenergieanlagen, Elektroautomobilen und vielen anderen Applikationen eingesetzt, bei denen die elektrische Energie in eine spezielle Form zu wandeln ist, um etwa Netzeinspeisung bei Windenergieanlagen oder eine spezifische Beschleunigung bei Elektroautomobilen zu realisieren. Bei ihrem Einsatz altern sie, dabei spielen Lastwechsel eine besondere Rolle. Es wird untersucht, welche Aspekte eine wichtige Rolle bei der Lastwechselbelastung einnehmen, wie sie zu berechnen und zu berücksichtigen sind. Am Beispiel von Leistungsmessdaten zweier an der mittelnorwegischen Küste betriebenen Windenergieanlagen wird beispielhaft gezeigt, wie die Lastwechselbelastung ermittelt werden kann. Im Rahmen der Arbeit wurde ein modularer 2000A Lastwechseltester entwickelt, gebaut und in Betrieb genommen, der mit einer neuen VCE(T) Kalibriermethode, der Aktiven Kalibrierung, ausgerüstet ist. Tester und Kalibriervorgang werden vorgestellt und im Detail diskutiert. Auf dieser Basis werden Perspektiven aufgezeigt, wie Lastwechseltester zukünftig optimiert gestaltet und die Messmethoden zur Alterungsbestimmung in die Applikation überführt werden können. / Power semiconductors are deployed in wind mills, electrical cars and many other applications whenever electrical energy has to be transformed into an intended form e.g. to feed-in wind energy or to accelerate a car. In use they fatigue at which power cycles play an important role. This work investigates the aspects taking the main role at power-cycle load, how they are to calculate and how to be considered. Based on power measurements of two wind mills placed at the middle Norwegian coast, it is shown how to determine the power cycle load. A modular 2000A power cycling test equipment has been developed, built-up and run-in. By means of this equipment a new VCE(T) calibration-method is demonstrated. The equipment as well as the calibration procedure is presented and discussed in detail. On that basis perspectives are depicted how power cycle equipment can be optimized and, moreover, methods for fatigue determination can be transferred from laboratory into application.

This work deals with the power cycling reliably of power modules and discrete devices. A small part was tested with standard test equipment, but the majority of devices were tested with an advanced test approach with additional switching losses. A large variety of packages under different conditions were tested: Discrete low-voltage silicon MOSFETs (<100 V), discrete SiC MOSFETs, baseplate-free SiC modules, medium power silicon modules and high power silicon modules. The core of the work is the investigation of low temperature swings in the transition between elastic and plastic deformation. During high operation temperatures, no significant increase in lifetime was observed, but at reduced junction temperatures, the impact was significant. All experimental results were transferred into a 3D simulation environment, for further investigation of the temperature and current distribution as well as the mechanical fatigue parameters, to allow a better understanding of the physical processes.

Dans le but de l’intégration des supercondensateurs dans des applicationstransport, la connaissance et l’étude de leur comportement au cours du vieillissementest nécessaire. L’objectif de cette thèse est donc la compréhension et lamodélisation des phénomènes de vieillissement observés sur lessupercondensateurs. Pour cela, des méthodologies de caractérisation électriques etdes protocoles expérimentaux originaux combinant les différentes contraintes devieillissement ont été mis en oeuvre. Des mesures du courant de fuite et des tests devieillissement combinés ont été effectués. Les résultats obtenus sont présentés. Ilsont ainsi servis au développement et l’implémentation de modèles permettant le suivide l’évolution des performances des supercondensateurs avec le vieillissement. / The study of the behavior of supercapacitors during ageing is required in orderto integrate them in transportation applications. The aim of this thesis is tounderstand and model ageing phenomena observed on supercapacitors. For thispurpose, electrical characterization methodologies and original experimentalprotocols combining various constraints of ageing have been implemented.Measurements of leakage current and combined ageing tests were conducted. Theobtained results were used for developing models allowing the monitoring of theevolution of supercapacitors performance during ageing.