Fredrik Bajers Vej 5
Postboks 159 9100 Aalborg
Telefon: 9940 9940
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15.09.2017 kl. 13.00 - 16.00
Emanuel Petre Eni, Department of Energy Technology, will defend the thesis "Characterisation and Analysis of high Voltage Silicon Carbide Mosfet".
Characterisation and Analysis of high Voltage Silicon Carbide Mosfet
Emanuel Petre Eni
Professor Remus Teodorescu
Associate Professor Erik Schaltz
Professor Francesco Iannuzzo, Dept. of Energy Technology, Aalborg University (Chairman)
Professor Johann Walter Kolar, ETH Zurich, Switzerland
Arnost Kopta, ABB Zurich, Switzerland
Silicon-Carbide materials, due to their physical properties, promise to provide improved performances in semiconductor switching devices in terms of breakdown voltages, switching frequency and operating temperatures. Continuous research in this field has already brought to the market SiC devices with voltages up to 3.3 kV which demonstrated superior performances compared to their Si counterparts in terms of efficiency and operating junction temperature. This also translated to a certain extent in improved reliability when considering the lower operating temperature of the Si devices for a similarly size heatsink.
Due to material properties and continuous research, 10 kV 4H-SiC devices are currently under development as engineering samples. These promise to be a good candidate for replacing Si based IBGTs in the high power high voltage applications where an improved efficiency and higher switching frequency could decrease the converter costs and size while offsetting the semiconductor higher price.
A very important requirement for power electronics devices employed in power converters is their reliability and behavior during transients such as short-circuits. This is highly relevant as the device needs to be able to sustain and safely turn-off such a transient in order for it to be consider as a suitable candidate for high voltage high power converters, where reliability is a key requirement.
Therefore the investigation of the behavior of the 10 kV 4H-SiC device during short-circuit and its degradation mechanism is of high interest. This summarizes both degradation during single event long short-circuit pulses but also during short and repetitive short-circuit events, which initially would not appear as a stress.
The work focused on studying the 10 kV first generation 4H-SiC DMOSFETs from Wolfspeed both in terms of device static and dynamic characteristics and short-circuit capability. As SiC still has to reach the technology maturity of Si, a theoretical comparison between SiC and Si highlights the better material properties of 4H-SiC in unipolar power devices. This was also emphasized by comparing the two semiconductor material figures of merit.
The dynamic behavior of the 10 KV SiC is studied to investigate the device behavior during operation at different voltages which the devices is expected to encounter during normal operation. The analysis provided a large 3D matrix of switching losses versus currents drain voltage and gate voltages for a large range of temperatures.
As the device showed promising results during switching, the short-circuit withstand capability, a relevant parameter for grid connected applications, has been investigated. This in term showed the device degrading at long pulses, with the degradation accumulating as the pulse lengths increased. Thermal simulations showed temperatures inside the package reaching surface metalization melting point. This triggered further investigations into the degradation mechanism in an attempt to isolate the possible root causes of the degradation. While the investigation could not find the exact culprit, as the device physical characteristics have not been shared by the manufacturer, it managed to narrow down the list of possible causes and identify the electrical parameters that degraded the most. Based on this, different hypothesis have been proposed in order to explain the observed degradation, some which have coincided with other findings published in literature.
In the end, it was clear that the high temperature reached in the device during long short-circuit transient was the main cause of the degradation. This high temperature in the device estimated based on the thermal simulation was confirmed and by a Scanning Electron Microscope investigation. Degradation of the SiC crystal structure, charges implanted in the oxide during the short-circuit, interface state charges or other similar material defects associated with the high temperature stressing and high electric field experienced during short‑circuit are the most plausible explanation for the degradation in device mobility.
Department of Energy Technology
Pontoppidanstræde 111, auditorium
27.09.2017 kl. 09.00 - 16.30
In honor of Professor Jane Parpart’s many years of contributions to our department, FREIA and CHI are hosting a special workshop titled Gender, Insecurities and Silences during Conflict and Peacebuilding 27th of September, 2017. We have invited a select group of junior and senior scholars across disciplinary boundaries to explore this issue further. We would like to open up this occasion also for other members of the department and university. Please sign up if you are interested in listening to the presentations (session A), take part in the discussions (session B), or both.
27.09.2017 kl. 13.00 - 16.00
Institut for læring og filosofi, Aalborg Universitet og Aalborg Universitetshospital har den glæde at invitere til ph.d.-forsvar ved sygeplejerske MLP Susanne Winther, Forskningsenhed for Klinisk Sygepleje, som forsvarer ph.d.-afhandlingen: FÆLLES FØLGESKAB -ET AKTIONSFORSKNINGSPROJEKT OM PATIENTOVERGANGE FRA INTENSIV TIL STAMAFSNIT
27.09.2017 kl. 16.00 - 18.00
September 27th from 16.00 - 18.00, we invite you to a nation-wide early premiere of Phie Ambo’s new exciting documentary “...when you look away”. The screening will be followed by a debate live-streamed directly from Skylab at DTU, which you can participate in by sending questions via SMS, twitter and facebook.
28.09.2017 kl. 09.00 - 12.00
Open workshop with Dr. Benjamin Schögler, Co-founder and Creative Director at Skoogmusic. Ben is passionate about making music accessible for everyone and was part of the NESTA team that invented SKOOG - an instrument that anyone can play.
28.09.2017 kl. 10.00 - 13.00
Anja Sloth Ziegler, Department of Chemistry and Bioscience will defend her thesis on: "The microbial community in fouling membrane bioreactors: Distribution and diversity of important bacteria"
28.09.2017 kl. 15.00 - 16.30
Præsentation ved henholdsvis professor og lektor ved Institut for Sociologi og Socialt Arbejde på AAU, Annick Prieur og Sune Qvotrup Jensen.
29.09.2017 kl. 09.00 - 17.00
Seminar on animation and visual research dissemination. Learning from state-of-the-art case-studies and ongoing research projects, we will discuss how 2D and 3D-visualisation and animation, narrative structures, and levels of temporal information can be combined in functional animation e.g. for educational or didactic purposes, or in the presentation or development of scientific material.
29.09.2017 kl. 09.00 - 17.30
This workshop brings together scholars from philosophy and history of science to help shed light on epistemological and historical cases of ‘evidence-based’ (or ‘informed’) policy and policymaking.
29.09.2017 kl. 13.00 - 16.00
Klinisk Institut, Aalborg Universitet og Aalborg Universitetshospital har den glæde at invitere til ph.d.-forsvar ved læge Jesper Moesgaard Rantanen, Nyremedicinsk Afdeling, som forsvarer ph.d.-afhandlingen: "Arrhythmias, Heart Rate Variability and Marine n-3 Polyunsaturated Fatty Acids in Patients on Chronic Dialysis"
29.09.2017 kl. 14.00 - 15.30
The seminar is open to all interested researchers!
02.10.2017 kl. 17.00 - 18.00
Mød uddannelsens faglige leder, Dorte Ågård, og hør mere om det faglige indhold. Bliv klogere på uddannelsens perspektiver og relevans i forhold til dit eget arbejdsområde eller interesseområde. Få svar på alle dine faglige og praktiske spørgsmål.
03.10.2017 kl. 13.00 - 16.30
Hør om de væsentligste ændringer, der forventes at komme i bygningsreglement BR18
04.10.2017 kl. 09.00 - 16.00
På dette kurset kan du lære, hvordan gulve, vægge og installationer kan udføres, så kravene i BR15 er overholdt, og så der opnås størst mulig sikkerhed mod skader fra vand og fugt.
04.10.2017 kl. 10.00 - 17.00
Writing has always been a key discipline to master within political sciences and humanities. Today writing articles and getting them published is more important than ever. Be it for the PhD-student using a collection of peer-reviewed and published articles as basis for the PhD, or for the young PhD aiming at a university career.
04.10.2017 kl. 13.00 - 17.00
Klinisk Institut, Aalborg Universitet og Aalborg Universitetshospital har den glæde at invitere til ph.d.-forsvar ved Steen Møller Hansen, Klinisk Epide-miologisk Afdeling, Aalborg Universitetshospital, som forsvarer ph.d.-afhandlingen: Opportunities and Limitations for Provid-ing Early Defibrillation of Out-of-hospital Cardiac Arrest Patients