abstract: With the penetration of distributed renewable energy and the development of semiconductor technology, power electronic devices could be utilized to interface re- newable energy generation and the distribution power grid. However, when directly connected to the power grid, the semiconductors inside the power electronic devices could be vulnerable to the power system transient, especially to lightning strikes. The work of this research focuses on the insulation coordination of power elec- tronic devices connected directly to the power distribution system. The Solid State Transformer (SST) in Future Renewable Electric Energy Delivery and Management (FREEDM) system could be a good example for grid connected power electronic devices. Simulations were conducted in Power Systems Computer Aided Design (PSCAD) software. A simulation done to the FREEDM SST showed primary re- sults which were then compare to simulation done to the grid-connected operating Voltage Source Converter (VSC) to get more objective results. Based on the simulation results, voltage surges caused by lightning strikes could result in damage on the grid-connected electronic devices. Placing Metal Oxide Surge Arresers (MOSA, also known as Metal Oxide Surge Varistor, MOV) at the front lter could provide eective protection for those devices from power transient. Part of this research work was published as a conference paper and was presented at CIGRE US National Conference: Grid of the Future Symposium [1] and North American Power Symposium [2]. / Dissertation/Thesis / Masters Thesis Engineering 2017

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Power electronic devices have become integral components in modern consumer and transportation industries. Predicting the failure or health status of these devices not only ensures operational safety and prevents catastrophic consequences but also leads to reduced downtime and operational costs. However, failure or health status prediction represents a complex problem marked by numerous intrinsic and extrinsic variables, leading to different lifetimes of devices. Additionally, selecting relevant precursor signals that effectively capture the underlying failure mechanisms and overcoming time-series prediction challenges, such as handling dynamic and non-linear behaviors, are crucial for accurate predictions. In the thesis, three models—Kalman filter (KF), Particle filter (PF), and Autoregressive Integrated Moving Average (ARIMA)—are applied, compared, and evaluated for failure or health status prediction of power electronic devices using Power Cycling (PC) test data for power diodes. Among the models, the KF demonstrates the most significant performance while consuming the least amount of time. The PF achieves the second-best performance and the third-best time consumption. Meanwhile, the in-sample ARIMA model delivers the third-best performance and the second-best time consumption. Finally, the out-of-sample ARIMA model ranked the lowest in both performance and time consumption. These results suggest that dynamic models, specifically the KF and PF, exhibit superior generalization capabilities across different devices. This underscores the potential of dynamic models for enhancing predictive accuracy while optimizing computational efficiency in the context of real-time power electronic device health monitoring. / Effektelektronikkomponenter har blivit integrerade delar av moderna konsument- och transportindustrier. Att förutsäga fel eller hälsotillstånd hos dessa enheter säkerställer inte bara operativ säkerhet och förebygger katastrofala konsekvenser utan leder också till minskad driftstopp och lägre driftskostnader. Dock representerar förutsägelse av fel eller hälsotillstånd en komplex uppgift som kännetecknas av många inbyggda och yttre variabler, vilket leder till olika livslängder för enheterna. Dessutom är det avgörande för noggranna förutsägelser att välja relevanta föregångssignaler som effektivt fångar upp de underliggande felmekanismerna och övervinna utmaningar med tidsberoende prediktion, såsom hantering av dynamiska och icke-linjära beteenden. I avhandlingen tillämpas, jämförs och utvärderas tre modeller - Kalman-filter (KF), partikelfilter (PF) och autoregressiv integrerad rörlig medelvärde (ARIMA) - för förutsägelse av fel eller hälsotillstånd hos effektelektronikkomponenter med hjälp av testdata för effektdioder från Power Cycling (PC). Bland modellerna visar KF den mest betydande prestandan samtidigt som den kräver minst tid. PF uppnår den näst bästa prestandan och den tredje bästa tidsåtgången. Samtidigt ger in-sample ARIMA-modellen den tredje bästa prestandan och den näst bästa tidsåtgången. Slutligen rankades out-of-sample ARIMA-modellen lägst både när det gäller prestanda och tidsåtgång. Dessa resultat tyder på att dynamiska modeller, särskilt KF och PF, uppvisar överlägsna generaliseringsförmågor över olika enheter. Detta understryker potentialen hos dynamiska modeller för att förbättra förutsägelseprecisionen samtidigt som de optimerar beräkningskapaciteten i sammanhanget av övervakning av hälsotillståndet för effektelektronikkomponenter i realtid.

L’utilisation des semi-conducteurs à large bande interdite (wide bandgap ou WBG) tels que le carbure de silicium SiC, le nitrure de gallium GaN, le diamant, etc… s’est répandue dans le domaine de l’électronique de puissance ces dernières décennies. Leurs caractéristiques électroniques et mécaniques font des WBGs des solutions alternatives pour remplacer le traditionnel silicium. Cependant, des études supplémentaires sont indispensables pour améliorer la tenue en tension, les pertes statiques et dynamiques et les performances en fonctionnement à haute température des composants WBGs. Dans ce cadre, deux bancs expérimentaux OBIC (Optical Beam Induced Current) spécifiques « en cours de développement » sont mis en place pendant cette thèse. L’OBIC consiste à éclairer avec un faisceau laser de longueur d’onde appropriée une jonction polarisée en inverse, des porteurs de charge sont alors créés par absorption photonique. On peut alors mesurer un courant induit par faisceau optique (OBIC) lorsque les porteurs sont générés dans la zone de charge d’espace. Après une première phase de préparation et d’adaptation de l’environnement expérimental, des essais ont mené à la démonstration du principe de génération multi-photonique en éclairant une jonction SiC avec un faisceau vert (532 nm). L’analyse des différentes mesures OBIC nous a permis de construire une image du champ électrique à la surface de la diode : une analyse non destructive pour étudier l’efficacité des protections périphériques des jonctions et pour détecter les défauts dans la structure cristalline. Egalement, la durée de vie des porteurs minoritaires a été déduite par l’analyse de la décroissance du courant OBIC au bord de la jonction. Les coefficients d’ionisation sont également déterminés par la méthode OBIC, ces coefficients sont des paramètres clés pour la prévision de la tension de claquage des composants. Nous avons réalisé des mesures OBIC dans le GaN, et nous avons observé un effet d’absorption bi-photonique dans le diamant avec un faisceau UV (349 nm). / In the last few decades, the use of wide bandgap (WBG) semiconductors (silicon carbide SiC, gallium nitride GaN, diamond, etc…) has become popular in the domain of power electronics. Their electronic and mechanical characteristics made of the WBGs a good alternative to the traditional silicon. However, additional studies are mandatory to improve the breakdown voltage, static and dynamic losses, and the performance at high temperature of the WBG devices. In this context, two specific experimental benches OBIC (Optical Beam Induced Current) -under development- are set up during this thesis. OBIC method consists to generate free charge carriers in a reverse biased junction by illuminating the device with an appropriate wavelength. An OBIC signal is measured if the charge carriers are generated in the space charge region. After a first phase of preparation and adaptation of the experimental environment, OBIC measurements led to demonstrate the multi-photonic generation by illuminating a SiC junction with a green laser (532 nm). OBIC measurements allowed giving an image of the electric field at the surface of the diode: OBIC presents a non-destructive analysis to study the efficiency of the peripheral protection and to detect the defects in the semi-conductor. Minority carrier lifetime was also deduced by studying the OBIC decrease at the edge of the space charge region. Ionization rates were extracted using OBIC method; these coefficients are key parameters to predict the breakdown voltage of the devices. OBIC measurements were also realized on the GaN, and two-photon generation was highlighted by measuring an OBIC current in the diamond when illuminating it with a UV laser beam (349 nm).